| 摘要 |
PROBLEM TO BE SOLVED: To reduce sulfur poisoning resistance by automatically stopping an engine after an engine switch is turned off and then regenerating operation of an exhaust emission control catalyst is carried out. SOLUTION: A lean NOx catalyst A is arranged on the way of an exhaust pipe, and a material added thiophene of 400ppm as sulfur in gasoline is used as fuel. An automobile is traveled for 10 hours at 50km per hour and in a lean operating condition, the engine switch is turned off, and regenerating treatment of an exhaust emission control catalyst is carried out by automatic control. The regenerating treatment is controlled in such a way that operation of engine only is changed from 5 seconds to 10 minutes without traveling the automobile in a condition of an stoichiometric air-fuel ratio or in a fuel excessive condition, and the temperature of the exhaust emission control catalyst is set to 250 to 600 deg.C. When the regenerating treatment time is set to 1 minute and the air-fuel ratio is set to 14.0, the more the regenerating treatment temperature is high, the more a NOx purifying ratio is high, and also the sulfur rate in the catalyst is reduced. It is thus possible to separate and reduce sulfur in the exhaust emission control catalyst, and it is also possible to suppress deterioration of the exhaust emission control catalyst. |
