Patent ID: 11898509
Assignee: NISSAN MOTOR CO., LTD.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F  Y | IPC F

Claim 0:
1. An exhaust gas recirculation (EGR) estimation method for estimating an EGR rate in an intake and exhaust system of an internal combustion engine, the EGR estimation method comprising:
providing the intake and exhaust system, which comprises:
an intake passage that is connected to the internal combustion engine,
an exhaust passage that is connected to the internal combustion engine,
an EGR valve in which a gap occurs even when the EGR valve is fully closed, due to a structure of the EGR valve, and
an EGR passage comprising an upstream EGR passage that connects the exhaust passage to the EGR valve, and a downstream EGR passage that connects the EGR valve to the intake passage;

when a fuel cut of the internal combustion engine is started with the EGR valve fully closed:
maintaining the EGR valve fully closed during the execution of the fuel cut of the internal combustion engine, and
during the execution of the fuel cut of the internal combustion engine and/or after fuel injection of the internal combustion engine is restarted, determining a gas replacement state by exhaust gas and fresh air in the upstream EGR passage; and

estimating the EGR rate based on a result of the determination of the gas replacement state.