| 摘要 |
PROBLEM TO BE SOLVED: To reduce deterioration of the combusting condition of an internal combustion engine even in the case a locking mechanism to lock the valve timing to the intermediate locking phase even when it deteriorates in operation performance. SOLUTION: A variable valve timing device is installed on an intake valve and an exhaust valve, and the variable valve timing device on the intake side is furnished with a locking mechanism to lock the intake valve timing to the intermediate locking phase at starting, etc. During execution of the variable valve timing control, determination is made for existence of failures in unlocking of the intake side variable valve timing device (steps 101 and 102), and if there is a failure produced, the exhaust side variable valve timing device is controlled, so that the exhaust valve timing goes into the most advanced phase, and the overlapping amount of the intake and exhaust valves is reduced, and thereby the internal EGR amount (rate of exhaust gas remaining in a cylinder) is reduced, to lead to suppression of deterioration of the combusting condition (step 104).
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