EXHAUST GAS RECIRCULATION DEVICE OF ENGINE

摘要

An exhaust gas recirculation device of an engine (10) of the invention comprises a first exhaust gas recirculation passage (50) for connecting an exhaust passage (40) and an intake passage (30) to each other and introducing into the intake passage an exhaust gas discharged from a combustion chamber (21) to the exhaust passage, and a second exhaust gas recirculation passage (55) for connecting the exhaust passage upstream of a part of the exhaust passage connected to the first exhaust gas recirculation passage and the intake passage downstream of a part of the intake passage connected to the first exhaust gas recirculation passage to each other and introducing into the intake passage the exhaust gas discharged from the combustion chamber to the exhaust passage. The amount of the exhaust gas introduced into the intake passage via the first exhaust gas recirculation passage is controlled to a first target exhaust gas recirculation amount and the amount of the exhaust gas introduced into the intake passage via the second exhaust gas recirculation passage is controlled to a second target exhaust gas recirculation amount. When a temperature of the flame on the combustion of a fuel is lower than or equal to an allowable upper limit flame temperature, a first reference exhaust gas recirculation amount set depending on the operation condition of the engine, is set as the first target exhaust gas recirculation amount and a second reference exhaust gas recirculation amount set depending on the operation condition of the engine, is set as the second target exhaust gas recirculation amount. When the temperature of the flame on the combustion of the fuel is higher than the allowable upper limit flame temperature, one of the first reference exhaust gas recirculation gas amount and an amount smaller than the first reference exhaust gas recirculation gas amount is set as the first target exhaust gas recirculation amount and an amount larger than the reference second exhaust gas recirculation amount is set as the second target exhaust gas recirculation amount.