| 摘要 |
There is provided an SCR system that can prevent fixation of urea solution to the interior of a dosing valve when the urea solution is not injected through the dosing valve. An SCR system 100 is configured to close a dosing valve 104 when the exhaust gas temperature is lower than the temperature at which the SCR catalyst becomes active and is provided with an fixation prevention system that opens the dosing valve 104 and controls a supply module 106 to feed the urea solution in the dosing valve 104 back to a urea tank 105 to prevent fixation of the urea solution to the interior of the dosing valve 104 when the exhaust gas temperature is equal to or higher than the temperature at which the urea solution crystallizes and lower than the temperature at which the SCR catalyst becomes active. |
