| 摘要 |
PURPOSE: A catalyst control method of exhaust gas for a vehicle is provided to prevent catalyst from being damaged by keeping the purification rate of catalyst for reducing exhaust gas. CONSTITUTION: The critical temperature threshold is set according to operation condition by modeling corresponding to characteristics of an oxygen sensor after catalyzing an engine(110), and compared with the reference value(120). The gradient is decreased with delaying time of lean decision gradient over the reference value(130), and the air fuel ratio is increased(140). Normal operation is decided below the reference value(150,160). The fuel amount is controlled by detecting the air fuel ratio to be rich or lean with the oxygen sensor. Instantaneous increase of exhaust temperature is prevented with lowering the gradient in deciding. Exhaust gas is reduced with keeping the purification rate of catalyst, and catalyst damage is prevented.
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