| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system capable of improving fuel economy and NOx purification performance under an environment that exhaust gas atmosphere varies over lean - stoichiometric - rich conditions in low exhaust gas temperature zone at 250°C or less. <P>SOLUTION: The exhaust emission control system is provided with exhaust emission control catalyst, an exhaust gas temperature detection means, a flow in CO quantity detection and estimation means and an adsorbed NOx quantity detection and estimation means, and performs rich atmosphere control based on a detection value and an estimation value of the flow in CO quantity detection and estimation means and the adsorbed NOx quantity detection and estimation means when a detection value of the exhaust gas temperature detection means is 250°C or less. The exhaust emission control catalyst to be used has a catalyst layer containing precious metal catalyst, NOx adsorbing material and oxygen adsorbing and discharging material formed on an integral construction type carrier. Consistency of NOx adsorbing material is high in surface side and consistency of oxygen adsorbing and discharging material is high in inner side. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
