| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem involved in a conventional exhaust emission control device that the generation of NO increases as the bed temperature of a NOcatalyst rises in a light load operating condition.SOLUTION: An exhaust emission control device 30 according to the present invention has a catalyst 30a arranged in an exhaust passage 28a for cleaning exhaust gas guided from an engine 10 into the exhaust passage. The exhaust emission control device 30 includes: load acquisition means 13, 15 for acquiring an engine load; first determination means 14a for determining whether the acquired engine load is light or not; means 33 for acquiring a catalyst bed temperature T; second determination means 14a for determining whether a catalyst bed temperature is between a first temperature at which the generation of NO is started in the exhaust gas and a second temperature at which the NO can be eliminated with the catalyst, or not; and bed temperature control means 11p, 11s, 14b, 14c, 14f, 14g, 14j, 14k, 17, 29 for lowering the catalyst bed temperature. When the catalyst bed temperature is between the first temperature and the second temperature in a light load operating condition, the catalyst bed temperature is controlled to be the first temperature or lower.SELECTED DRAWING: Figure 2 |
