| 摘要 |
PROBLEM TO BE SOLVED: To provide a good NOx reducing effect from low exhaust gas temperature as compared with a conventional device even for a vehicle of an operation style with which an operation condition of low exhaust gas temperature continues for a long period of time. SOLUTION: This exhaust emission control device is composed of NOx occlusion material 10 installed in a middle of an exhaust pipe 9 and oxidizing NOx in exhaust gas and temporarily occluding the same as nitrate and decomposing and discharging NOx with intervention of reducing agent at a time of drop of oxygen concentration, oxidation catalyst 13 installed in upper stream of the NOx occlusion material, a fuel adding means (a fuel injection device 17, a control device 16) adding fuel in exhaust gas 8 as reducing agent in an upper stream side of the oxidation catalyst, selective reduction type catalyst 12 installed right after the NOx occlusion material 10 and making NOx selectively react with ammonia even under existence of oxygen, and a urea water adding means (a urea water tank 19, urea water supply pipe 20, a supply pump 21, an injection nozzle 23) adding urea water 22 in the exhaust gas 8 as reducing agent at an inlet side of the selective reducing type catalyst. COPYRIGHT: (C)2005,JPO&NCIPI
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