| 摘要 |
The objective of the present invention is to reduce the amount of NOx discharged from an internal combustion engine when NOx which has been adsorbed on a NOx storage reduction catalyst is reduced. This exhaust purification device is for an internal combustion engine equipped with: a NOx storage reduction catalyst that is provided in the exhaust passage of the internal combustion engine, and that adsorbs NOx in the exhaust air and reduces this NOx when the air-fuel ratio is equal to or less than the theoretical air-fuel ratio; an air-fuel ratio control unit that changes the air-fuel ratio in the internal combustion engine; and an EGR device that connects the exhaust passage and the intake passage of the internal combustion engine, thereby supplying a portion of the exhaust air as EGR gas to the intake passage. This exhaust purification device is equipped with an EGR rate control unit which controls the EGR device such that, when the NOx adsorbed on the NOx storage reduction catalyst is reduced by changing the air-fuel ratio in the internal combustion engine, the EGR rate is higher when the target air-fuel ratio is lower than when the target air-fuel ratio is higher. |
