| 摘要 |
The present invention relates to an exhaust purification system and detects an internal NH 3 adsorption amount with high precision. An exhaust purification system includes an SCR catalyst (32) disposed at an exhaust system of an engine (10) for using ammonia that is generated from urea water as a reducing agent to reduce and purify NOx contained in exhaust gas, a urea water injection device (31) that injects urea water to the SCR catalyst (32), an inlet-side electrode (37) that detects capacitance within the SCR catalyst (32) at least from the vicinity of the inlet of the SCR catalyst to the vicinity of an intermediate section in an exhaust gas flowing direction, an outlet-side electrode (38) that detects the capacitance within the SCR catalyst (32) at least from the vicinity of the intermediate section to the outlet of the SCR catalyst in the exhaust gas flowing direction, and an NH 3 adsorption amount calculation unit (52) that calculates the ammonia adsorption amount within the SCR catalyst (32) on the basis of the capacitance entered from the inlet-side electrode (37) and the capacitance entered from the outlet-side electrode (38). |
