| 摘要 |
PROBLEM TO BE SOLVED: To provide an internal combustion engine that can suppress deterioration of exhaust emissions caused by scavenging.SOLUTION: An internal combustion engine 100 includes a supercharger 101, variable valve timing mechanisms B, C, a catalyst 20, an upstream side air-fuel ratio sensor 40, a downstream side air-fuel ratio sensor 41 and an air-fuel ratio control system. When the blow-by amount air blowing from an intake passage through inside of a cylinder to an exhaust passage is equal to or smaller than reference blow-by amount, the air-fuel ratio control system sets a target air-fuel ratio of inflow exhaust gas on the basis of an air-fuel ratio detected by the downstream side air-fuel ratio sensor, and performs feedback control of fuel amount supplied to a combustion chamber so that an air-fuel ratio detected by the upstream side air-fuel ratio sensor corresponds to the target air-fuel ratio. When the blow-by amount exceeds the reference blow-by amount, the air-fuel ratio control system sets the target air-fuel ratio of the inflow exhaust gas on the basis of the air-fuel ratio detected by the downstream side air-fuel ratio sensor, and supplies fuel amount calculated from the target air-fuel ratio to the combustion chamber without performing the feedback control.SELECTED DRAWING: Figure 11 |
