| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, capable of restricting fluctuation of an air-fuel ratio of exhaust gas flowing into a catalyst converter while maintaining purification performance of the catalyst converter high, and securely determining deterioration of the catalyst converter while minimizing deterioration of purification performance. <P>SOLUTION: This device is provided with an air-fuel ratio modulation means S10, S12, and S14 to modulate the combustion air-fuel ratio to modulation amplitude of the combustion air-fuel ratio in the internal combustion engine so as to reduce the amplitude of exhaust air-fuel ratio in exhaust gas flowing into the catalyst converter, an average air-fuel ratio setting means to set average air-fuel ratio X1 in a modulation cycle of the exhaust air-fuel ratio modulated by the air-fuel ratio modulation means to be a theoretical air-fuel ratio or a rich air-fuel ratio, and a sole lean making means S18 to solely making the combustion air-furl ratio to be lean for a prescribed period regardless of the air-fuel ratio modulation means. A downstream side exhaust sensor is provided to detect and output a component concentration of exhaust gas on the exhaust downstream side of the catalyst converter. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
