AIR-FUEL RATIO CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To control the air-fuel ratio based on an oxygen occlusion state or the like at a specific position in catalyst in an air-fuel ratio control device for an internal combustion engine to purify exhaust gas by the catalyst disposed in an exhaust passage.

SOLUTION: The catalyst to purify the exhaust gas is disposed in the exhaust passage in the internal combustion engine. Quantity of excess or lack of oxygen Cgout (N) in the exhaust gas flowing in the catalyst is determined for every position in a flow direction of exhaust gas (every block divided supposedly). In addition, a convergence point X in the catalyst where the quantity of excess or lack of oxygen in exhaust gas Cgout (N) becomes zero is detected (step 102). In a case where the convergence point is transferring downstream of a target point (step 104), the air-fuel ratio of mixed gas supplied to the internal combustion engine is controlled in such a way that its convergence point transfers upstream (step 106).

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