초록 ▼

Secondary air is supplied to a position upstream of a catalyst disposed in an exhaust passage of an engine. An oxygen sensor is disposed between a secondary air supply portion of the exhaust passage and the catalyst. The supply amount of the secondary air is feedback controlled so that the oxygen co

Secondary air is supplied to a position upstream of a catalyst disposed in an exhaust passage of an engine. An oxygen sensor is disposed between a secondary air supply portion of the exhaust passage and the catalyst. The supply amount of the secondary air is feedback controlled so that the oxygen concentration in the exhaust gas detected by the oxygen sensor approaches a target value corresponding to a theoretical air/fuel ratio. A second oxygen sensor for air/fuel ratio control is disposed upstream of the secondary air supply portion. Air/fuel ratio feedback control adjusts the air/fuel ratio of air entering the engine so that the oxygen concentration at the second oxygen sensor approaches the same target value as at the other oxygen sensor.

대표청구항 ▼

A method for controlling secondary air for an internal combustion engine comprising the steps of: detecting oxygen concentration at a position between a catalyst provided in an engine exhaust passage for emission control and a secondary air supply portion provided in said exhaust passage upstream of

A method for controlling secondary air for an internal combustion engine comprising the steps of: detecting oxygen concentration at a position between a catalyst provided in an engine exhaust passage for emission control and a secondary air supply portion provided in said exhaust passage upstream of said catalyst; setting an amount of said secondary air so that the detected oxygen concentration approaches a target value by detecting an intake air flow amount of the engine and varying the operational magnitude of the secondary air amount depending upon the detected intake air flow amount of the engine wherein the target value is a value corresponding to a theoretical air/fuel ratio; controlling the supply of the secondary air on the basis of the set secondary air amount by opening an electromagnetic valve disposed in a path of pressurized secondary air, depending upon the set secondary air amount; detecting oxygen concentration in the exhaust gas at a position upstream of said secondary air supply portion; feedback controlling an air/fuel ratio of an air/fuel mixture to be introduced into the engine so that the detected oxygen concentration at a position upstream of said secondary air supply portion approaches a target value that is the same as the target value of said secondary air amount; and forcibly stopping the supply of said secondary air while said air/fuel ratio feedback control is active.