| 摘要 |
PROBLEM TO BE SOLVED: To surely reduce the intake air pipe volume, and to improve idle stability when becoming an idle condition after sudden rotational reduction by sudden braking in an intake air device of an engine having an intake air variable valve capable of switching the intake air pipe volume. SOLUTION: An accelerator full closing state is detected by an idle switch as an operation state of predicting the sudden braking (S1). A switching engine speed Ns is set to an ordinary value (for example, 2,200 rpm) except for accelerator full closing time (S2). The switching engine speed Ns is set to the high rotation side (for example, 3,000 rpm) at accelerator full closing time (S3). An engine speed N is detected (S4), and is compared with the switching engine speed Ns (S5), and when the engine speed is not more than Ns, the intake air variable valve is closed to reduce the intake air pipe volume (S6). When exceeding Ns, the intake air variable valve is opened to increase the intake air pipe volume (S7).
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