| 摘要 |
To improve injection efficiency and stability of post injection required for regeneration of a nitrogen oxide occlusion catalyst. An average post-injection amount as a post-injection amount that is unambiguously determined for each cylinder on the basis of PID control, an-air fuel ratio detected by a lambda sensor, and a target average air-fuel ratio as a target air-fuel ratio is computed (S100). Next, a post-injection deviation by cylinder that corresponds to an excess/shortage amount in a post-injection amount for each of the cylinders with respect to the average post-injection amount is computed on the basis of a characteristic deviation by cylinder that corresponds to a variation in the air-fuel ratio of each of the cylinders (S200 and S300). Post injection is performed by setting an addition result of the average post-injection amount and the post-injection deviation by cylinder as a post-injection amount by cylinder that is the post-injection amount required for each of the cylinders to realize the target average air-fuel ratio. |
