| 摘要 |
PURPOSE:To prevent the occurrence of which smoke by increasing the exhaust gas recirculation flow when the suction pressure downstream a suction throttle section becomes a predetermined value or lower in a Diesel engine performing suction throttling during an idle operation. CONSTITUTION:When an engine is in operation, a control device 25 controls to open both negative pressure control valves 21, 22 and fully open an auxiliary suction throttle valve 16 during the warmup operation with the detected temperature of the cooling water by a water temperature sensor 28 at a predetermined value or lower, and to open only the negative pressure control valve 22 and half-open the auxiliary suction throttle valve 16 after the warmup is completed. Furthermore, the control device determines the standard EGR gas flow Qe based on outputs of an acceleration sensor 29 and a rotation speed sensor 26. When the detected value Pi of the suction pipe negative pressure by a suction pressure sensor 26 is predetermined value or lower and there is a fear of the occurrence of white smoke, a pulse signal with a duty ratio in response to the flow with the flow augmentation quantity DELTAQe increasing in response to the reduction of the suction pressure added to the said flow Qe is applied to a negative pressure control valve 43 to control the opening of an EGR valve 34. |
