| 摘要 |
PROBLEM TO BE SOLVED: To prevent steps in gas flow rate or chattering upon operation of an EGR valve and to reduce hysteresis. SOLUTION: In an exhaust gas recirculation control apparatus, the EGR valve 1 adjusting an exhaust gas recirculation amount has a drive circuit 2 supplying a drive current by duty control, so as to change a duty ratio and thereby to adjust opening of the EGR valve 1. Drive frequency of the drive circuit 2 is variable, and a calculating part 4 is disposed so that the calculating part 4 lowers the drive frequency as drive duty corresponding to opening detected by an opening detecting means 3 becomes large. Thereby, smoothing of current variation prevents the steps in flow rate or the chattering on a side where the drive duty is small, and elongation of a continuous turned-on period facilitates operation on a side where the drive duty is large. COPYRIGHT: (C)2004,JPO
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