| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a combustion condition by appropriately detecting ion current irrespective of change of operation condition of an internal combustion engine in a combustion condition determining device for an internal combustion engine. SOLUTION: An ion current detection circuit 56 detecting ion current corresponding to quantity of ion generated by combustion of air fuel mixture in a combustion chamber 18 is provided, and the combustion condition of the engine 10 can be detected based on the detected ion current. In this case, a drop rate d is detected by comparing base ion current average value Ib detected under a normal condition where deposit is not adhered on a spark plug 37 and reference ion current average value Is detected under a predetermined operation condition (stoichiometric + MBT) of the engine 10. Ion current correction value Ir is calculated by correcting ion current value Im detected at the time of cold start of the engine 10 by the drop rate d. Combustion deterioration of the engine 10 is detected by comparing the ion current correction value Ir with a determination value of the combustion condition. COPYRIGHT: (C)2007,JPO&INPIT
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