EXHAUST PURIFICATION SYSTEM

摘要

An exhaust purification system includes a selective catalytic reduction (SCR) catalyst disposed at an exhaust system of an engine for using ammonia that is generated from urea water as a reducing agent to reduce NOx contained in exhaust gas, a device that injects urea water to the SCR catalyst, an inlet-side electrode that detects capacitance within the SCR catalyst at least from a vicinity of an inlet of the SCR catalyst to a vicinity of an intermediate section in an exhaust gas flowing direction, an outlet-side electrode that detects the capacitance within the SCR catalyst at least from the vicinity of the intermediate section to an outlet of the SCR catalyst in the exhaust gas flowing direction, and a calculation unit that calculates an ammonia adsorption amount within the SCR catalyst on a basis of the capacitances detected from the inlet-side and the outlet-side electrodes.

主权项

1. An exhaust purification system comprising:
at least one selective reduction catalyst arranged in an exhaust system of an internal combustion engine and configured to reduce nitrogen compounds contained in exhaust gas with ammonia generated from an aqueous urea solution as a reducing agent for purification of the exhaust gas; an aqueous urea solution injection unit configured to inject the aqueous urea solution to the selective reduction catalyst; a first capacitance detecting unit configured to detect a first capacitance in the selective reduction catalyst, at least from a vicinity of an inlet of the selective reduction catalyst to a vicinity of a middle of the selective reduction catalyst in an exhaust gas flowing direction; a second capacitance detecting unit configured to detect a second capacitance in the selective reduction catalyst, at least from a vicinity of a middle of the selective reduction catalyst to a vicinity of an outlet of the selective reduction catalyst in the exhaust gas flowing direction; and a reducing agent adsorption amount calculation unit configured to calculate an adsorbed amount of the reducing agent in the selective reduction catalyst based on the detected first capacitance and second capacitance.