| 摘要 |
PROBLEM TO BE SOLVED: To improve the nitrogen oxide occluding efficiency of a NOx occlusion reduction catalyst by cooling exhaust gas in a simple configuration.SOLUTION: An exhaust emission control device includes: a NOx occlusion reduction catalyst 212 provided in a main exhaust passage (an exhaust passage 140) into which exhaust gas exhausted from a combustion chamber 146 of an engine 120 is guided, for occluding nitrogen oxide in a predetermined temperature range; a water adsorbing material 230 provided in a bypass passage 220 branching from the main exhaust passage and merging with the main exhaust passage for adsorbing water at lower than a water adsorbing temperature being not higher than an upper limit value in the predetermined temperature range and releasing the water at not lower than the water adsorbing temperature; and a flow path control part for, when the temperature of the exhaust gas on the upstream side of the NOx occlusion reduction catalyst exceeds the upper limit value in the predetermined temperature range, controlling a flow path for the exhaust gas so that the exhaust gas, after passing through the water adsorbing material arranged in the bypass passage, passes through the NOx occlusion reduction catalyst.SELECTED DRAWING: Figure 4 |
