| 摘要 |
PROBLEM TO BE SOLVED: To accurately determine a combustion condition in accordance with an ion current in an exhaust stroke. SOLUTION: A system determines the combustion condition in accordance with the ion current detected via an ignition plug in the exhaust stroke. An ion detection starting timing in the exhaust stroke is set to be at a bottom dead center or later (ATDC 180°CA or later), and the ion current is detected in a period when a difference between the detection level of the ion current during stable combustion and that during instable combustion is greater to determine the combustion condition. Furthermore, considering that a period from an exhaust stroke starting timing (a valve opening timing T1 for an exhaust valve) to sufficient lowering of the detection level of the ion current is changed depending on engine operating conditions including an engine speed and a load, the ion detection starting timing in the exhaust stroke is set to be variable depending on the engine operating conditions including a load factor and the engine speed Ne. COPYRIGHT: (C)2007,JPO&INPIT
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