| 摘要 |
PURPOSE:To prevent worsening of combustion during warming-up and decrease of an intake air amount after warming-up, by a method wherein reflux of high temperature EGR gas through a first EGR passage and reflux of low temperature EGR gas through a second EGR passage are effected according to an operating condition and a warming-up condition. CONSTITUTION:First and second EGR passage 21 and 22, through which a suction passage 2 and an exhaust passage 4 located down a line from a suction throttle valve 6 are intercommunicated, are formed. A first EGR control valve 24 is located in the first EGR passage 21, and a second EGR control valve 26 and a cooler 27, cooling reflux exhaust, are located in the second EGR passage 22. Meanwhile, a load sensor 18 and a rotation sensor 19, both detecting an operating condition, and a water temperature sensor 38, detecting a warming-up condition, are provided, and based on the detecting values thereof, a control circuit 39 controls the openings of the throttle valve 6 and the first and second EGR control valves 24 and 26. This performs reflux of high temperature EGR gas through the first EGR passage 21 as it is during warming-up, and effects reflux of EGR gas cooled through the second EGR passage 22 during normal operation after warming-up. |
