| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology capable of favorably performing the air-fuel ratio degradation control by suppressing degradation of the fuel economy in the air-fuel ratio degradation control in an exhaust emission control device of an internal combustion engine. <P>SOLUTION: In the exhaust emission control device of the internal combustion engine for regenerating the performance of a NOx catalyst by performing the rich spike control for degrading the air-fuel ratio of an exhaust gas by feeding a fuel to the exhaust gas of the internal combustion engine, the wall temperature of an exhaust gas passage is estimated, and the execution permission is determined for permitting the execution of the rich spike control when the estimated wall temperature exceeds the predetermined value, and prohibiting the execution of the rich spike control when the estimated wall temperature is lower than the predetermined value. The estimated wall temperature is corrected for determining acceptance/rejection of the next rich spike control based on the gradient of the change in the air-fuel ratio when the air-fuel ratio is degraded in the rich spike control under execution. <P>COPYRIGHT: (C)2008,JPO&INPIT |
