| 摘要 |
PROBLEM TO BE SOLVED: To improve fuel consumption by enlarging an operation region capable of obtaining scavenging effect.SOLUTION: An engine includes a turbo supercharger 20 including a turbine 22 and a compressor 23, an EGR passage 45 communicating an exhaust passage 30 at a downstream side with respect to the turbine 22 and an intake passage 10 at an upstream side with respect to the compressor 23, an EGR valve 47 disposed in the EGR passage 45, and a valve variable mechanism 16 capable of changing opening and closing timings of an intake valve 6 and an exhaust valve 7. The EGR valve 47 is opened in operation regions (R1, R2) where a flow rate of an exhaust gas becomes a prescribed value or less, and in particular, in a specific supercharging region (R2) positioned at a high load side in the operation region, a valve overlap control is executed to drive the valve variable mechanism 16 so that the overlap period when both of the intake valve 6 and the exhaust valve 7 are opened, is secured by a prescribed amount or more before and after an exhaust top dead point. |
