Patent ID: 11898509

Abstract:
An EGR estimation method for an internal combustion engine 1 estimates an EGR rate in an intake and exhaust system 10, 20 of an internal combustion engine, the intake and exhaust system 10, 20 of an internal combustion engine including an intake system 10, an exhaust system 20, and an EGR device 40, the EGR device 40 includes an EGR passage 41 and an EGR valve 43. The EGR estimation method includes determining a gas replacement state by exhaust gas and fresh air in an upstream EGR passage, which is a portion of the EGR passage between the EGR valve and the exhaust passage, when fuel cut of the internal combustion engine is started and the EGR valve is fully closed; and estimating the EGR rate based on a result of the determination.