To recirculate exhaust gas even under an operation condition where intake passage internal pressure is higher than exhaust passage internal pressure by supercharging, and prevent a supercharger from being damaged by exhaust gas.
An engine 10 has a supercharger 20, an air supplying passage 53 branched from an intake passage 30 on the downstream side of the supercharger 20 is connected to the air supplying side of the turbine 52 of an exhaust circulating air sending device 50 formed of the turbine 52 and a compressor 51 concentrically connected thereto, and a circulated exhaust suction passage 54 branched from an exhaust passage 40 is connected to the suction side of the compressor 51 of the exhaust circulating air sending device 50. Thus, the discharge side of the compressor 51 is connected to an air route portion extended from an impeller 21A to a diffuser 21B in the compressor 21 of the supercharger 20 through a circulated exhaust discharge passage 55, the exhaust circulating air sending device 50 is driven by the compressed air (the energy thereof) supplied through the air supplying passage 53, and the exhaust gas in the exhaust passage 40 is sucked and pressurized through the circulated exhaust suction passage 54, and supplied to the intake passage 30 through the circulated exhaust discharge passage 55.
IKETANI NOBUYUKI
KONDO NOBUHIRO
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