| 摘要 |
A rich control for temporarily declining an air-fuel ratio of exhaust gas discharged from an engine combustion chamber is performed by an additional fuel being injected into a cylinder in an expansion stroke or an exhaust stroke in a state where a throttle opening degree is switched from a base throttle opening degree to a throttle opening degree for the rich control and an EGR rate is switched from a base EGR rate to an EGR rate for the rich control. The rich control is terminated by returning the throttle opening degree (VTH) to the base throttle opening degree (VTHB), stopping the injection of the additional fuel (Qa), and temporarily increasing the amount of a main fuel (Qm). Then, an EGR control valve opening degree (VEGR) is controlled such that the EGR rate (REGR) is returned to the base EGR rate (REGRB). |
