| 摘要 |
PROBLEM TO BE SOLVED: To accelerate activation of a catalyst after engine starting by delaying the ignition timing more quickly up to an allowable limit in terms of the combustion stability. SOLUTION: The deterioration of the combustion stability at the time when the ignition timing is delayed, is correlated to a decrease in generating torque, and the combustion stability is quickly deteriorated at a torque-quick reducing point. An average effective pressure PI equivalent to the generating torque is detected from he angular speed of a crankshaft in a period of combustion, and is divided by an intake air flow Qa to determine an average effective pressure PI per a fixed intake air flow (S21). The value before starting the ignition delay is regarded as an reference value PISET (S23), and until the difference (PISET-PI) between this value and the last value PI reaches a specified amount PING (S25), the ignition timing is gradually delayed. When the specified amount PING is reached, the torque-quick reducing point is regarded as being reached, and thus the ignition delay is stopped. Since the correction of the ignition delay is performed for every combustion, its speed is accelerated.
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