| 摘要 |
<p>The present invention has for its object to provide a technology in which in an exhaust gas purification apparatus for an internal combustion engine which is provided with a catalyst for NH 3 generation, and a catalyst for removing or reducing NOx in an exhaust gas by using NH 3 as a reducing agent, NOx in the exhaust gas can be reduced, even in cases where the NH 3 generation capacity of the catalyst for NH 3 generation has become low. In order to solve this object, the exhaust gas purification apparatus for an internal combustion engine of the invention is provided with a three-way catalyst and a storage reduction catalyst as catalysts for NH 3 generation, wherein when the NH 3 generation capacity of the storage reduction catalyst does not become low, NH 3 is made to be generated in the storage reduction catalyst by adjusting the air fuel ratio of the exhaust gas flowing into the storage reduction catalyst to a first predetermined rich air fuel ratio, whereas when the NH 3 generation capacity of the storage reduction catalyst becomes low, NH 3 is made to be generated in the three-way catalyst by adjusting the air fuel ratio of the exhaust gas flowing into the three-way catalyst to a second rich air fuel ratio which is higher than the rich air fuel ratio and lower than a theoretical air fuel ratio.</p> |
