| 摘要 |
PROBLEM TO BE SOLVED: To avoid the deterioration of follow-up property of control by the excessive increase in target EGR valve opening while limiting the actual EGR valve opening to the equivalence of full opening. SOLUTION: The actual EGR quantity is estimated and calculated, and the EGR valve opening is closed-loop controlled by PI control based on the deviation with the target EGR quantity according to an operation state. When the target EGR quantity cannot be realized when the EGR valve opening reaches full opening, the target EGR valve opening becomes excessively larger than the equivalence of full opening by steady deviation, and when the target EGR quantity is reduced at time t1, the follow-up property is deteriorated. In this invention, when the target EGR valve opening is equivalent to full opening, and the deviation is positive, the input of P control is set to a constant, and the output of I control is reset, whereby the target EGR valve opening is held at the equivalence of full opening. Accordingly, when the target EGR quantity is reduced at the time t1, the EGR valve opening is immediately reduced. COPYRIGHT: (C)2004,JPO
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