JP2009270492A - Failure diagnosis device of cylinder deactivation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely determine the existence of failure of a cylinder deactivation system that keeps intake valves and exhaust valves of a part of cylinders of an engine in a closed state so as to stop the operation of the cylinders concerned. <P>SOLUTION: During operation of the engine, cylinder deactivation control is executed when predetermined cylinder deactivation control execution conditions are established. In the cylinder deactivation control, the cylinder deactivation system keeps the intake valves and discharge valves of the part of cylinders in a closed state so as to stop the suction and discharge of air, thereby stopping the operation of the cylinders concerned, and cylinder-reduction operation in which the engine is operated by the remaining cylinders is performed. During the cylinder-reduction operation, it is determined based on an output of a highly responsive airflow meter whether intake air pulsation corresponding to an intake stroke of each cylinder exists or not. When it is determined that the intake air pulsation, corresponding to the intake stroke of each of the deactivation-instructed cylinders which are instructed to be deactivated by the cylinder deactivation system, exists, or when it is judged that there is no intake air pulsation corresponding to an intake stroke of each operation-instructed cylinder, it is determined that failure exists in the cylinder deactivation system as for the cylinder concerned. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a failure diagnosis device for a cylinder deactivation system including a cylinder deactivation device that deactivates some cylinders of an internal combustion engine.

  In recent years, a vehicle equipped with an internal combustion engine stops intake and exhaust by maintaining the intake valves and exhaust valves of some cylinders of the internal combustion engine in a closed state (a lift amount is zero) for the purpose of improving fuel efficiency. A cylinder deactivation device for deactivating the operation of the cylinder, and in the operation region where the load of the internal combustion engine is relatively small, the operation of some cylinders is deactivated by the cylinder deactivation device and the internal combustion engine is operated with the remaining cylinders There are some which are designed to perform reduced-cylinder operation.

Further, as described in Patent Document 1 (Japanese Patent Laid-Open No. 4-183942), in a system including a variable valve timing device that changes the valve timing (opening / closing timing) of an intake valve and an exhaust valve of an internal combustion engine, Compare the intake air amount for judgment per rotation calculated based on the engine operating state (throttle opening, engine speed, etc.) and the actual intake air amount per rotation calculated based on the output of the air flow meter. An actual valve timing (operating state of the variable valve timing device) is determined, and the actual valve timing is compared with a target valve timing to determine whether or not the variable valve timing device has failed.
Japanese Patent Laid-Open No. 4-183942 (see page 6 to page 7)

  By the way, the above-described cylinder deactivation device maintains the intake valves and exhaust valves of some cylinders in a closed state to stop intake and exhaust, thereby reducing the operation of the cylinders and operating the internal combustion engine with the remaining cylinders. In a vehicle equipped with a cylinder deactivation system that performs cylinder operation, if the cylinder deactivation device fails, pumping loss occurs when the intake valve or exhaust valve is opened or closed in the cylinder (deactivation cylinder) that is deactivated during reduced cylinder operation. As fuel consumption deteriorates and unintended cylinders perform intake / exhaust operations, an error occurs in fuel metering, or unburned oxygen is exhausted into the exhaust system, causing the exhaust temperature to rise. May cause inconveniences such as

  However, the technique of Patent Document 1 is a technique for determining whether or not there is a failure in a variable valve timing device that uniformly changes the valve timing of all cylinders of an internal combustion engine. This is not a technique for determining whether or not there is a failure in the cylinder deactivation device that maintains the exhaust valve in a closed state and deactivates the cylinder.

  Further, if the cylinder deactivation system is used in the cylinder deactivation system, the determination intake air per rotation calculated based on the engine operating state (throttle opening, engine speed, etc.) during the reduced-cylinder operation. Even if an attempt is made to determine the operating state of the cylinder deactivation device by comparing the amount and the actual intake air amount per rotation calculated based on the output of the air flow meter, the intake valve or the exhaust valve is determined by only one of the deactivated cylinders. When there is a failure that opens and closes, since the change in the actual intake air amount per revolution is small, it is difficult to determine the operating state of the cylinder deactivation device, and the presence or absence of the failure of the cylinder deactivation device is accurately determined. It is difficult to determine, and there is an inconvenience that a failed cylinder cannot be specified.

  The present invention has been made in view of these circumstances. Therefore, the object of the present invention is to accurately determine whether or not a cylinder deactivation device has malfunctioned that deactivates some cylinders of an internal combustion engine. An object of the present invention is to provide a failure diagnosis device for a cylinder deactivation system.

  In order to achieve the above object, an invention according to claim 1 includes a cylinder deactivation device and a cylinder deactivation device that deactivate the operation of the cylinder by maintaining at least the intake valves of some cylinders of the internal combustion engine. An intake air amount of an internal combustion engine is detected in a cylinder deactivation system including a cylinder deactivation control unit that performs control to perform a reduced cylinder operation in which some cylinders are deactivated and the remaining cylinders are operated. An intake air amount detection means is provided, and an intake pulsation corresponding to the intake stroke of each cylinder is determined by the intake pulsation determination means based on the output of the intake air amount detection means, and the cylinder deactivation control means determines the cylinder deactivation during the reduced cylinder operation. Information indicating whether or not the cylinder is instructed to stop the operation (hereinafter referred to as “stop instruction cylinder”) and information on the intake pulsation corresponding to the intake stroke of each cylinder determined by the intake pulsation determining means. It is obtained so as to determine the failure diagnosis means the presence or absence of a failure of the cylinder deactivation device Zui.

  If the cylinder deactivation device is normal, during the reduced cylinder operation, the operation instruction cylinder other than the deactivation instruction cylinder opens the intake valve for each intake stroke and sucks air into the cylinder. Intake pulsation occurs corresponding to the intake stroke, but in the stop instruction cylinder, the intake valve is maintained in the closed state and air is not sucked into the cylinder, and therefore no intake pulsation corresponding to the intake stroke of the stop instruction cylinder occurs. . Paying attention to such characteristics, if the information on whether or not the cylinder is a deactivation instruction cylinder and the information on the intake pulsation corresponding to the intake stroke of each cylinder during the reduced-cylinder operation are used, it is possible to accurately determine whether or not the cylinder deactivation device has failed. Can be determined. In addition, since it is possible to determine whether or not there is a failure of the cylinder deactivation device for each cylinder, there is also an advantage that the cylinder in which the failure of the cylinder deactivation device has occurred can be specified.

  In this case, as described in claim 2, when it is determined that there is an intake pulsation corresponding to the intake stroke of the deactivation instruction cylinder during the reduced cylinder operation, it is preferable to determine that there is a failure in the cylinder deactivation device. If the cylinder deactivation device is normal, intake pulsation corresponding to the intake stroke of the deactivation instruction cylinder does not occur. Therefore, if it is determined that there is intake pulsation corresponding to the intake stroke of the deactivation instruction cylinder, It can be determined that there is a failure.

  Further, as in claim 3, when it is determined that there is no intake pulsation corresponding to the intake stroke of the operation command cylinder other than the stop command cylinder during the reduced cylinder operation, it is determined that the cylinder deactivation device is faulty. Also good. If the cylinder deactivation device is normal, intake pulsation occurs corresponding to the intake stroke of the operation instruction cylinder. Therefore, if it is determined that there is no intake pulsation corresponding to the intake stroke of the operation instruction cylinder, the cylinder deactivation device It can be determined that there is a failure.

  By the way, if the cylinder deactivation device fails, and the intake valve of the deactivation instruction cylinder is opened and closed during the reduced cylinder operation, the pumping loss increases as described above, resulting in a deterioration in fuel consumption or an error in the air-fuel ratio. Or the exhaust temperature may increase.

  Therefore, as in claim 4, fail safe control means for prohibiting the reduced cylinder operation when it is determined that there is a failure of the cylinder deactivation device may be provided. In this way, it is possible to prevent the inconvenience as described above from occurring due to the malfunction of the cylinder deactivation device due to the intake valve of the deactivation instruction cylinder being opened and closed during the reduced cylinder operation.

  Alternatively, as in claim 5, fail safe control means may be provided for changing the deactivation instruction cylinder when it is determined that there is a failure in the cylinder deactivation device. In this way, even when the cylinder deactivation device is out of order, the cylinder deactivation operation can be performed while preventing the occurrence of adverse effects caused by opening and closing of the intake valve of the deactivation instruction cylinder during the cylinder deactivation operation.

  Further, as in claim 6, the throttle opening may be corrected to the open side during the reduced-cylinder operation. In this way, since the intake air amount of the operation command cylinder can be increased during the reduced cylinder operation to increase the torque generated in the operation instruction cylinder, the torque reduction due to the reduced cylinder operation can be prevented and the output of the internal combustion engine can be prevented. Torque can be kept constant. In addition, by correcting the throttle opening to the open side during the reduced-cylinder operation, the intake air pulsation corresponding to the intake stroke of the operation instruction cylinder can be easily transmitted to the detection position of the intake air amount detection means. This makes it possible to improve the accuracy of determining the intake pulsation based on the output of the engine, and to improve the accuracy of the failure diagnosis of the cylinder deactivation device using the intake pulsation.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided upstream of the intake pipe 12 of an internal combustion engine, for example, a V-6 engine 11. An air flow meter 14 (intake air amount detection) detects the intake air amount downstream of the air cleaner 13. Means). This air flow meter 14 is a high response type air flow meter in which the sensor output changes with good response to the intake air amount pulsating for each intake stroke of each cylinder.

  A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, an intake manifold 18 that introduces air into each cylinder of the engine 11 is provided on the downstream side of the throttle valve 16, and a fuel injection valve 19 that injects fuel near each intake port of the intake manifold 18 of each cylinder. It is attached. Further, a spark plug 20 is attached to each cylinder of the cylinder head of the engine 11, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug 20.

  A crank angle sensor 23 that outputs a pulse signal every time the crankshaft 21 rotates a predetermined crank angle is attached to the outer peripheral side of the signal rotor 22 attached to the crankshaft 21 of the engine 11. The crank angle and engine speed are detected based on the output signal.

  Further, in the engine 11, the intake valve 25 and the exhaust valve 26 are closed for each of a plurality of preset cylinder groups (for example, the cylinder group of one bank and the cylinder group of the other bank of the V-type engine). A cylinder deactivation device 27 for deactivating the operation of the cylinder group by stopping intake and exhaust while maintaining the above is provided. Note that the cylinder deactivation device 27 may be provided only in some cylinder groups (for example, the cylinder group in one bank of the V-type engine).

  The cylinder deactivation device 27 switches, for example, the cams that open and close the intake valve 25 and the exhaust valve 26 to cams that have a cam profile that maintains the valve lift amount at 0, respectively. It is comprised so that 26 can be maintained in a closed state. The intake valve 25 and the exhaust valve 26 may be configured by electromagnetically driven valves so that the intake valve 25 and the exhaust valve 26 can be kept closed.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 24. The ECU 24 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 19 according to the engine operating state. The ignition timing of the spark plug 20 is controlled.

  Further, the ECU 24 executes the cylinder deactivation control routine when a predetermined cylinder deactivation control execution condition is satisfied by executing the cylinder deactivation control routine of FIG. 2 during engine operation in order to improve the fuel consumption of the engine 11. . In this cylinder deactivation control, the cylinder deactivation device 27 maintains intake valves 25 and exhaust valves 26 of some cylinder groups (for example, cylinder groups in one bank of a V-type engine) in a closed state to stop intake and exhaust. At the same time, the fuel injection is stopped to stop the operation of the cylinder group, and the reduced cylinder operation is performed in which the engine 11 is operated in the remaining cylinder group (for example, the cylinder group in the other bank of the V-type engine).

  Further, the ECU 24 determines whether or not there is an intake pulsation corresponding to the intake stroke of each cylinder based on the output of the air flow meter 14 during the reduced-cylinder operation, and instructs the cylinder deactivation device 27 to deactivate the operation ( Whether or not there is a failure in the cylinder deactivation device 27 is determined on the basis of information on whether or not the cylinder deactivation apparatus 27 is inactive) and information on the intake pulsation corresponding to the intake stroke of each cylinder.

  As shown by the solid line in FIG. 3, if the cylinder deactivation device 27 is normal, operation instruction cylinders other than the deactivation instruction cylinder (for example, the first cylinder # 1, the third cylinder # 3, and the fifth cylinder) during the reduced cylinder operation. In the cylinder # 5), the intake valve 25 is opened for each intake stroke, and air is sucked into the cylinder. Therefore, intake pulsation occurs in response to the intake stroke of the operation instruction cylinder. In the second cylinder # 2, the fourth cylinder # 4, and the sixth cylinder # 6), since the intake valve 25 is maintained in the closed state and no air is sucked into the cylinder, the intake corresponding to the intake stroke of the deactivation instruction cylinder is performed. No pulsation occurs.

  Therefore, as shown by a broken line in FIG. 3, when it is determined that there is an intake pulsation corresponding to the intake stroke of the deactivation instruction cylinder, a failure of the cylinder deactivation device 27 (for example, the intake valve 25 of the deactivation instruction cylinder opens and closes). It is determined that there is an operation failure). Even when it is determined that there is no intake pulsation corresponding to the intake stroke of the operation instruction cylinder, there is a failure of the cylinder deactivation device 27 (for example, a failure in which the intake valve 25 of the operation instruction cylinder is kept closed). judge.

Hereinafter, the processing content of the cylinder deactivation control routine of FIG. 2 executed by the ECU 24 will be described.
The cylinder deactivation control routine shown in FIG. 2 is executed at a predetermined cycle during engine operation. When this routine is started, first, in step 101, the output of the crank angle sensor 23, the output of the air flow meter 14, and the like are read.

  Thereafter, the process proceeds to step 102 to determine whether or not the cylinder deactivation control execution condition is satisfied. For example, the engine speed, the engine load (cylinder charged air amount, throttle opening, etc.), vehicle speed, accelerator opening, etc. Judgment is made based on whether or not in a predetermined reduced-cylinder operation region and steady operation.

  If it is determined in this step 102 that the cylinder deactivation control execution condition is not satisfied, this routine is terminated without performing the processes in and after step 103. In this case, the intake valve 25 and the exhaust valve 26 are opened and closed in all cylinders to perform intake and exhaust, and fuel injection is performed to perform the all cylinder operation for operating the engine 11.

  On the other hand, if it is determined in step 102 that the cylinder deactivation control execution condition is satisfied, the process proceeds to step 103, where cylinder deactivation control is performed. In this cylinder deactivation control, the cylinder deactivation device 27 maintains intake valves 25 and exhaust valves 26 of some cylinder groups (for example, cylinder groups in one bank of a V-type engine) in a closed state to stop intake and exhaust. At the same time, the fuel injection is stopped to stop the operation of the cylinder group, and the reduced cylinder operation is performed in which the engine 11 is operated in the remaining cylinder group (for example, the cylinder group in the other bank of the V-type engine). During this reduced-cylinder operation, the throttle opening is corrected to the open side to increase the intake air amount of the operation instruction cylinder and increase the generated torque of the operation instruction cylinder. Thereby, the torque reduction due to the reduced cylinder operation is compensated to keep the output torque of the engine 11 constant. Further, by correcting the throttle opening to the open side during the reduced-cylinder operation, the intake pulsation corresponding to the intake stroke of the operation instruction cylinder is easily transmitted to the detection position of the air flow meter 14. The processing in step 103 serves as cylinder deactivation control means in the claims.

  Thereafter, the routine proceeds to step 104, where it is determined whether or not there is an intake pulsation corresponding to the intake stroke for each cylinder based on the output of the air flow meter 14 during the reduced cylinder operation. In this case, for example, the fluctuation amount of the output of the air flow meter 14 (the difference between the maximum value and the minimum value) between the top dead centers corresponding to the intake stroke is obtained for each cylinder, and the fluctuation amount of the output of the air flow meter 14 pulsates. It is determined whether or not there is an intake pulsation corresponding to the intake stroke depending on whether or not it is larger than the determination value. Generally, since the magnitude of intake pulsation changes depending on the engine operating state (for example, engine speed, engine load, etc.), the pulsation judgment value depends on the engine operating state (for example, engine speed, engine load, etc.). To set. The processing in step 104 serves as intake pulsation determining means in the claims.

  Thereafter, the routine proceeds to step 105, where it is determined whether or not the combination of the information indicating whether or not each cylinder is a deactivation instruction cylinder (whether or not deactivation instruction is present) and the information regarding the presence or absence of intake pulsation corresponding to the intake stroke is correct. If it is determined in step 105 that the combination of the information indicating whether or not the cylinder is the deactivation instruction cylinder and the information regarding the presence or absence of the intake pulsation corresponding to the intake stroke is specifically determined, specifically, this corresponds to the intake stroke of the deactivation instruction cylinder. When it is determined that there is no intake pulsation, or when it is determined that there is intake pulsation corresponding to the intake stroke of the operation instruction cylinder, the routine proceeds to step 106 and it is determined that there is no failure (normal) of the cylinder deactivation device 27. To do.

  On the other hand, if it is determined in step 105 that the combination of the information indicating whether or not the cylinder is the deactivation instruction cylinder and the information regarding the presence or absence of the intake pulsation corresponding to the intake stroke is not correct, specifically, the deactivation instruction cylinder When it is determined that there is an intake pulsation corresponding to the intake stroke of the engine, or when it is determined that there is no intake pulsation corresponding to the intake stroke of the operation instruction cylinder, the routine proceeds to step 107, and the cylinder is deactivated in the corresponding cylinder. It is determined that there is a failure in the device 27 (for example, a failure in which the intake valve 25 of the deactivation instruction cylinder opens or closes or a failure in which the intake valve 25 of the operation instruction cylinder is kept closed), and the abnormality flag of the corresponding cylinder is turned ON. The warning lamp (not shown) provided on the instrument panel of the driver's seat is turned on, or the warning display part (not shown) of the instrument panel of the driver's seat is turned on. ) Is displayed to warn the driver, and the abnormality data (abnormality code or the like) is stored in a rewritable nonvolatile memory (such as a backup RAM (not shown)) of the ECU 24 or the like even when the ECU 24 is powered off. Stored in a rewritable memory. The processing of these steps 105 to 107 plays a role as failure diagnosis means in the claims.

  Thereafter, the process proceeds to step 108, and when it is determined that there is a failure in the cylinder deactivation device 27, the reduced-cylinder operation is prohibited. The processing of step 108 serves as fail-safe control means in the claims.

  In the present embodiment described above, when the cylinder deactivation device 27 is normal, intake pulsation occurs in the operation instructing cylinder corresponding to the intake stroke during the reduced cylinder operation, but in the deactivation instruction cylinder, the intake pulsation corresponds to the intake stroke. Focusing on the fact that no intake pulsation occurs, the presence or absence of failure of the cylinder deactivation device 27 is determined by a combination of information on whether or not the cylinder is a deactivation instruction cylinder and information on the presence or absence of intake pulsation corresponding to the intake stroke during reduced cylinder operation. Since the determination is made, it is possible to accurately determine whether or not the cylinder deactivation device 27 has failed. In addition, since it is possible to determine whether or not the cylinder deactivation device 27 has failed for each cylinder, the cylinder in which the failure of the cylinder deactivation device 27 has occurred can be identified.

  Further, in this embodiment, the throttle opening is corrected to the open side during the reduced-cylinder operation, so that the intake pulsation corresponding to the intake stroke of the operation instruction cylinder is easily transmitted to the detection position of the air flow meter 14, The determination accuracy of the intake pulsation based on the output of the air flow meter 14 can be increased, and the diagnosis accuracy of the failure diagnosis of the cylinder deactivation device 27 using the intake pulsation can be improved.

  Further, in this embodiment, when it is determined that there is a failure in the cylinder deactivation device 27, the reduced cylinder operation is prohibited. Therefore, even when the cylinder deactivation device 27 has failed, the deactivation instruction cylinder can be used during the reduced cylinder operation. Thus, adverse effects such as an increase in pumping loss, an air-fuel ratio error, and an increase in exhaust gas temperature can be prevented.

  When it is determined that there is a failure in the cylinder deactivation device 27, the deactivation instruction cylinder is changed from the cylinder group of one bank of the V-type engine to the cylinder group of the other bank to perform the reduced cylinder operation. Also good. In this way, even when the cylinder deactivation device 27 breaks down, the cylinder depressurization operation is performed while the intake valve 25 of the deactivation instruction cylinder is opened and closed during the decelerating operation and the above-described adverse effects are prevented. Can do.

  Further, in the present embodiment, the present invention is applied to a cylinder deactivation system in which both the intake valve 25 and the exhaust valve 26 of the deactivation instruction cylinder are maintained in the closed state, but only the intake valve 25 of the deactivation instruction cylinder is maintained in the closed state. The present invention may be applied to a cylinder deactivation system.

  Further, the scope of application of the present invention is not limited to a V-type 6-cylinder engine, but can be applied to other types of engines (for example, an inline engine or a horizontally opposed engine), or 5 cylinders or less (for example, The present invention may be applied to engines with 4 cylinders, 5 cylinders, etc. and engines with 7 cylinders or more (for example, 8 cylinders, 10 cylinders, 12 cylinders, etc.).

  In addition, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, but includes an in-cylinder injection type engine, and both an intake port injection fuel injection valve and an in-cylinder injection fuel injection valve. It can also be applied to dual-injection engines.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a flowchart explaining the flow of a process of a cylinder deactivation control routine. It is a time chart explaining failure diagnosis of a cylinder deactivation device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Air flow meter 14 (intake air amount detection means), 16 ... Throttle valve, 19 ... Fuel injection valve, 20 ... Spark plug, 23 ... Exhaust pipe, 24 ... ECU (Cylinder deactivation control means, intake pulsation determination means, failure diagnosis means, fail-safe control means), 25 ... intake valve, 26 ... exhaust valve, 27 ... cylinder deactivation device

Claims (6)

A cylinder deactivation device that stops at least the intake valves of some cylinders of the internal combustion engine and closes the operation of the cylinders, and deactivates some cylinders by the cylinder deactivation devices and performs internal combustion in the remaining cylinders In a cylinder deactivation system comprising cylinder deactivation control means for controlling to perform reduced cylinder operation for operating an engine,
Intake air amount detection means for detecting the intake air amount of the internal combustion engine;
An intake pulsation determining means for determining an intake pulsation corresponding to an intake stroke of each cylinder based on an output of the intake air amount detecting means;
Information on whether or not the cylinder is instructed to stop operation by the cylinder deactivation device by the cylinder deactivation control means during the reduced cylinder operation (hereinafter referred to as “deactivation instruction cylinder”) and each of the determinations made by the intake pulsation determination unit A failure diagnosing device for a cylinder deactivation system, comprising: failure diagnosis means for determining whether or not the cylinder deactivation device has failed based on intake pulsation information corresponding to the intake stroke of the cylinder.   The failure diagnosis means determines that the cylinder deactivation device is defective when the intake pulsation determination means determines that there is an intake pulsation corresponding to the intake stroke of the deactivation instruction cylinder during the reduced cylinder operation. 2. The failure diagnosis device for a cylinder deactivation system according to claim 1, wherein   The failure diagnosis means has a malfunction of the cylinder deactivation device when the intake pulsation determination means determines that there is no intake pulsation corresponding to the intake stroke of the operation instruction cylinder other than the deactivation instruction cylinder during the reduced cylinder operation. The failure diagnosis device for a cylinder deactivation system according to claim 1 or 2, characterized in that   4. The cylinder according to claim 1, further comprising a fail-safe control unit that prohibits the reduced-cylinder operation when the failure diagnosis unit determines that there is a failure in the cylinder deactivation device. Fault diagnosis device for hibernation system.   4. The cylinder according to claim 1, further comprising a fail-safe control unit that changes the deactivation instruction cylinder when it is determined by the failure diagnosis unit that the cylinder deactivation device is malfunctioning. 5. Fault diagnosis device for hibernation system.   6. The failure diagnosis apparatus for a cylinder deactivation system according to claim 1, wherein the cylinder deactivation control means corrects the throttle opening to the open side during the reduced cylinder operation.

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