| 摘要 |
PURPOSE:To control knocking effectively, by restricting a control amount in a spark-advance control when a knocking restricting effect is obtained once by a spark-retard control of an ignition timing. CONSTITUTION:A controller 22 reads knocking strength of an engine 1 from a knocking sensor 20 and discriminates its operating condition. When the operating condition shows that knocking is caused within a knocking control region, a minimum spark-retard amount and a spark-retard amount in the operating region is set and an ignition timing is delayed by a prescribed value. When the knocking is eliminated by the spark-retard control, the spark-retard amount is gradually reduced and the ignition timing is advanced. However, a control is effected in such a manner that the spark-retard amount is not less than the minimum spark-retard amount for a prescribed period after the knocking is eliminated. With this arrangement, a knocking restricting effect can be secured continuously. |
