| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a catalyst from becoming an overheat state by the occurrence of an abnormal cylinder of largely fluctuating the air-fuel ratio in the lean direction, in a system for controlling the air-fuel ratio of respective cylinders, based on output of an air-fuel ratio sensor arranged in an exhaust confluent part of an internal combustion engine. <P>SOLUTION: The existence of a lean abnormal cylinder of largely fluctuating the air-fuel ratio in the lean direction, is determined based on the air-fuel ratio of the respective cylinders estimated based on the output of the air-fuel ratio sensor 37. When determining that there is the lean abnormal cylinder, reaction heat such as the catalyst 38 becomes the overheat state (a state of being damaged by heat), is not generated by limiting an exhaust gas quantity (an oxygen quantity) flowing in the catalyst 38 by performing limiting operation control for limiting engine output. Thus, even when the air-fuel ratio of exhaust gas flowing in the catalyst 38 is deviated in the lean direction by the occurrence of the lean abnormal cylinder, the catalyst 38 can be prevented from becoming the overheat state. <P>COPYRIGHT: (C)2008,JPO&INPIT |
