| 摘要 |
PROBLEM TO BE SOLVED: To improve hydrolyzing efficiency while suppressing production of deposit from an urea aqueous solution injected and added to an upstream side of a selective reduction catalyst for removing nitrogen oxide (NOx) of an internal combustion engine.SOLUTION: An inclination angle &thetas;k to a central axis of an expansion pipe 71, of an inner peripheral face of the expansion pipe 71 is smaller than a spray angle &thetas;f to a spray central axis of an injection nozzle 15, so that a spray tip portion reaches and attaches to the inner peripheral face of the expansion pipe 71, and exhaust air including the injected urea aqueous solution passing through an internal passage 121 inside of the expansion pipe 71, and exhaust air passing through an outer passage 122 between the outer peripheral face of the expansion pipe 71 and an inner and outer double pipe 110, are joined at a downstream side of the expansion pipe 71, and flow into a SCR catalyst. |
