| 摘要 |
An engine exhaust gas cleaning apparatus is provided to suppress EGR ratio fluctuations when the excess air ratio is adjusted and thereby stabilize the engine operating performance. The engine exhaust gas cleaning apparatus comprises an exhaust gas recirculation control valve configured to recirculate a portion of the exhaust gas from the exhaust system to the air intake system and feedback control the quantity of the recirculated exhaust; an intake air throttle valve arranged in the air intake system at a position upstream of the position where an exhaust gas recirculation passage connects to the air intake system; an excess air ratio control section configured to change the intake air quantity by using the intake air throttle valve in response to a request to adjust the excess air ratio; and a feedback control restricting section configured to temporarily prohibit feedback control of the exhaust gas recirculation quantity delivered by the exhaust gas recirculation control valve, or to temporarily lower the gain of the feedback control, when the excess air ratio is being adjusted.
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