| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a rich gas impartment evaluation method which can further exactly decide an impartment condition of a rich gas.SOLUTION: In a rich gas impartment evaluation method, a calculation part 107 which evaluates an impartment amount of a rich gas to a catalyst 101 estimates a reduction progress position which indicates a degree of the progress of reduction in the catalyst 101 along a flow direction of an exhaust gas on the basis of whether or not values of a plurality of air-fuel sensors 102, 103, 104 and 105 which are arranged in the catalyst 101 along a flow direction of the exhaust gas discharged from an engine 1 reach prescribed values after imparting the rich gas to the catalyst 101 under a prescribed impartment condition, decides the reduction progress position which satisfies a prescribed quantitative relationship with a purification holding time being a time at which the catalyst 101 imparted with the rich gas can continue to reduce a nitrogen oxide contained in the exhaust gas at a prescribed ratio, and decides an impartment condition for reducing the catalyst 101 up to the decided reduction progress position.</p> |
