| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a SCR system for preventing ammonia slip independently of how an engine is controlled. <P>SOLUTION: The SCR system 103 includes a urea water amount calculating part 1 for calculating a urea water amount for NOx reduction depending on a NOx amount in exhaust gas, and an injection amount restricting part 2 for prohibiting a urea water injection amount from a dosing valve 104 from exceeding a urea water amount equivalent to a maximum NOx amount to be reduced by the SCR device 103 during a low water temperature when the temperature of cooling water in the engine E is a preset lower limit value or lower, or during a low outside air temperature determined by the fact that boost pressure is a preset lower limit value or lower, by multiplying the urea water amount calculated by the urea water amount calculating part 1 by a predetermined coefficient to determine the urea water injection amount from the dosing valve 104. <P>COPYRIGHT: (C)2012,JPO&INPIT |
