| 摘要 |
PROBLEM TO BE SOLVED: To prevent hydrocarbons from flowing into the downstream side of NOx occlusion reduction catalyst. SOLUTION: An exhaust emission control converter 10 is placed on an exhaust path 3 of an internal combustion engine 1. The exhaust emission control converter 10 is configured to arrange a NOx occlusion reduction catalyst 7, HC absorbent member 11, oxidation catalyst 13 in this order from the upstream inside a casing. The HC absorbent member 11 selectively absorbs heavy hydrocarbon components among the exhaust air, and when the temperature rises it converts the absorbed heavy hydrocarbons into light hydrocarbons and emits it. When a reductant (fuel) is supplied from a reductant supply device 9 into an exhaust path, at the upstream of the converter 10 at low temperatures, hydrocarbons that did not react on NOx occlusion reduction catalyst 7 flow to the downstream of the catalyst 7. Among those hydrocarbons, heavy components are adsorbed into the HC adsorbent member, while light component is purified further by oxidation catalyst at the downstream side. Hydrocarbons emitted from the HC adsorbent member after the temperature rises are purified by oxidation catalyst on the downstream side, therefore emission of hydrocarbons into the air is prevented completely. |
