Patent ID: 8359830

Claim:
An exhaust gas purification device for an internal combustion engine, the exhaust gas purification device comprising: an NO X selective reducing catalyst disposed in an exhaust passage of the internal combustion engine; a urea injector disposed in the exhaust passage upstream of the NO X selective reducing catalyst that feeds urea to the NO X selective reducing catalyst such that an ammonia generated from the urea is adsorbed by the NO X selective reducing catalyst, the adsorbed ammonia being used by the NO X selective reducing catalyst to selectively reduce NO X contained in an exhaust gas; an NO X sensor disposed in the exhaust passage downstream of the NO X selective reducing catalyst and that detects NO X and ammonia contained in the exhaust gas downstream of the NO X selective reducing catalyst; and an electronic control unit having control logic configured to: (i) judge whether or not a feed of fuel to the engine has been stopped during a deceleration operation, and (ii) judge whether or not an amount of adsorption of ammonia at the NO X selective reducing catalyst is saturated based on a detection value of the NO X sensor which is obtained: (a) when the electronic control unit has judged that the feed of fuel to the engine has been stopped and while the feed of the fuel to the engine remains stopped during the deceleration operation, (b) while no NO X is produced by the internal combustion engine, and (c) while feeding of the urea by the urea injector is stopped.