| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve reduction efficiency of NOx in a high temperature area of exhaust gas. <P>SOLUTION: A first selective reduction type catalyst 21 made of a copper-based catalyst, an iron-based catalyst, a zinc-based catalyst or a cobalt-based catalyst, is arranged in an exhaust pipe 16 of an engine 11, and a second selective reduction type catalyst 22 made of a silver-based catalyst is arranged in the exhaust pipe 16 on the exhaust gas downstream side of the first selective reduction type catalyst 21. A liquid injection nozzle 26 capable of injecting a hydrocarbon-based liquid 24 toward the first selective reduction type catalyst 21, is arranged in the exhaust pipe 16 on the exhaust gas upstream side of the first selective reduction type catalyst 21, and a hydrocarbon-based liquid supply means 27 is constituted so as to supply the liquid 24 to the liquid injection nozzle 26 via a liquid injection quantity adjusting valve 31. A controller 38 is constituted so as to control the liquid injection quantity adjusting valve 31 based on detection output of a first temperature sensor 41 for detecting the temperature of exhaust gas related to the first selective reduction type catalyst 21. <P>COPYRIGHT: (C)2012,JPO&INPIT |
