| 摘要 |
PROBLEM TO BE SOLVED: To determine the malfunction of a lock mechanism for engaging/ disengaging tappets in a valve device of an engine where a valve is directly driven via tappets divided in such a way that they can be engaged/disengaged. SOLUTION: The device comprises a vibration sensor for detecting the vibration of a cam shaft caused by the collision of a center tappet and a cam for high lift, a hydraulic sensor for detecting hydraulic oil pressure fed to the lock mechanism and an air flow sensor for detecting an intake quantity to the engine, and signals detected by the sensors are outputted to a control unit. The control unit determines a abnormality on a hydraulic control valve side in a step S4, and determines defective switching in the lock mechanism in steps S5 and S6. If the abnormality or defective switching is determined, an alarm lamp is lighted in a step S9 in either case, and an operation is controlled so that a current high-speed operation mode is switched to a low-speed operation mode. COPYRIGHT: (C)2004,JPO
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