| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce torque reduction in an internal combustion engine as much as possible when recirculation of exhaust gas by an EGR device and rich spike control are performed in an exhaust emission control system of an internal combustion engine equipped with the EGR device that recirculates a part of the exhaust gas further on the downstream side than a reducing agent adding valve in the internal combustion engine. <P>SOLUTION: In the rich spike control, a base air-fuel ratio AFb is reduced within a range of a combustion fluctuation ΔCC not exceeding an allowable limit ΔCCL (S108). When the combustion fluctuation ΔCC exceeds the allowable limit ΔCCL, a base air-fuel ratio AFbs in spike is corrected to the lean side (S213), and when a torque reduction amount ΔTD is greater than an allowable value ΔTDL, the base air-fuel ratio AFbs in spike is corrected to the rich side (S215). When the combustion fluctuation ΔCC exceeds the allowable limit ΔCCL and the torque reduction amount ΔTD is greater than the allowable value ΔTDL, the base air-fuel ratio AFbs in spike is corrected to the lean side and a fuel discharge number EN is increased (S216). <P>COPYRIGHT: (C)2008,JPO&INPIT |
