Exhaust gas purification system abnormality diagnosing device and abnormality diagnosing method, and exhaust gas purification system

Abstract

The present invention particularly relates to an exhaust gas purification system abnormality diagnosing device and abnormality diagnosing method and to an exhaust gas purification system that determines the abnormality of the exhaust gas purification system without making the NOX concentration of the downstream side or the Ammonia concentration of the downstream side obviously rise. The abnormality diagnosing device includes: a sensor value detecting means that reads a sensor signal of a specified gas concentration sensor to detect a gas concentration; a limiting device controlling means which, when the gas concentration has become equal to or greater than a predetermined start-of-diagnosis threshold value or when a difference obtained by subtracting from the gas concentration an estimated NOX concentration on a downstream side of a selective reduction catalyst obtained by computation has become equal to or greater than a predetermined start-of-diagnosis threshold value, increases the quantity of ammonia capable of being adsorbed by the selective reduction catalyst by raising the pressure inside an exhaust gas passageway with a passageway area limiting device disposed on the downstream side of the selective reduction catalyst; and a determining means that determines the abnormal state on the basis of the gas concentration or the difference after the pressure inside the exhaust gas passageway has been raised.

Description

technical field [0001] The present invention relates to an abnormality diagnosis device and an abnormality diagnosis method of an exhaust purification system and the exhaust purification system. In particular, it relates to the use of ammonia to reduce NO in exhaust gases X An abnormality diagnosis device and an abnormality diagnosis method of an exhaust gas purification system (nitrogen oxides), and an exhaust gas purification system. Background technique [0002] Nitrogen oxides (hereinafter referred to as "NO X ”) is more often. As the NO X In an exhaust purification system for purifying exhaust gas, it is known that a reducing agent derived from ammonia is injected on the upstream side of a selective reduction catalyst included in an exhaust passage, ammonia is adsorbed on the selective reduction catalyst, and the inflow is selectively reduced. NO in the exhaust gas of the catalyst X An exhaust purification system that reacts with ammonia to purify exhaust gas. [0...

AI Technical Summary

Problems solved by technology

However, if the entire exhaust purification system deteriorates, the deviation of the actual injection amount from the target injection amount may increase in some cases, or the catalyst efficiency may decrease. Selecting the NO on the downstream side of the reduction catalyst X Concentration or ammonia concentration will exceed the allowable value

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