| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device for an internal combustion engine capable of raising a catalyst temperature to a constant temperature even if an intake temperature is changed when removing a sulfur content in an exhaust emission control catalyst. Ž<P>SOLUTION: The air-fuel ratio control device has a common merging exhaust passage to which exhaust passages connected to a plurality of cylinders are merged, the exhaust emission control catalyst disposed in the merging exhaust gas passage, and an intake temperature obtaining means for obtaining the intake temperature. According to a sulfur content removing demand, a portion of the cylinders becomes rich cylinders in which the exhaust air-fuel ratio is rich, and at least one cylinder out of the remaining cylinders becomes a lean cylinder in which the exhaust air-fuel ratio is lean. When the intake temperature is lower than a first reference temperature, the degree of the richness of the rich cylinders and the degree of the leanness of the lean cylinder are raised, and when the intake temperature is higher than a second reference temperature defined to be the first reference temperature or higher, the degree of the richness of the rich cylinders and the degree of the leanness of the lean cylinder are lowered. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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