| 摘要 |
PROBLEM TO BE SOLVED: To reduce NOx in exhaust gas by effecting reflux of exhaust gas to a cylinder in all the operation regions of an engine without boosting EGR gas and reinforcing an engine. SOLUTION: An intake passage 15 to feed air to a cylinder through a compressor housing 11a is connected to an intake port 14, and an exhaust passage 17 to exhaust gas in a cylinder in the atmosphere through a turbine housing 11b is connected to an exhaust port 16. An EGR valve 21b to regulate exhaust gas returned to the intake passage is situated in an EGR passage 21a to interconnect the exhaust passage and the intake passage and an external EGR device 21 consists of the EGR passage and the EGR valve. Further, the engine 12 is provided with an internal EGR device to open the exhaust valve during the intake stroke of the cylinder and introduce exhaust gas in the cylinder. Based on the detecting outputs of a rotation sensor 43 and a load sensor 44, a controller 46 and the EGR valve are controlled. |
