| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device for an internal combustion engine, including an air-fuel ratio sensor provided downstream of an exhaust emission control catalyst, and correctly controlling an air-fuel mixture supplied to a combustion chamber in rich control or lean control based on an output value from the air-fuel ratio sensor. SOLUTION: The exhaust emission control catalyst 52 is arranged in an exhaust passage 50, and the air-fuel ratio sensor 54 is arranged in the exhaust passage downstream of the exhaust emission control catalyst. When the rich control over the air-fuel ratio of the air-fuel mixture is started, the amount of fuel supplied to the combustion chamber 25 is increased. Time required for exhaust gas after burning of fuel to reach the air-fuel ratio sensor is called exhaust gas arrival time, and time required for the air-fuel ratio sensor to output an output value corresponding to the air-fuel ratio of the exhaust gas received by the air-fuel ratio sensor is called sensor output time. Control over the air-fuel ratio of the air-fuel mixture based on the output value from the air-fuel ratio sensor in the rich control is started when time with the sensor output time added to the exhaust gas arrival time after the amount of fuel supplied to the combustion chamber is increased is passed or thereafter. COPYRIGHT: (C)2011,JPO&INPIT |
