| 摘要 |
An air-fuel ratio control system is provided that enables a prompt restoration ofair-fuel ratio control to a normal state after an injection of secondary air upstream of a catalyst, the cut of fuel injection, or deceleration leaning, and enables keeping emission performance high. At a stage at which the injection of secondary air is started or at a stage at which fuel cut control or deceleration leaning is performed, sliding mode control in a main body 100 of an air-fuel ratio controller is interrupted. Immediately after the injection of secondary air is finished or immediately after the fuel cut control or the deceleration leaning is finished, the air-fuel ratio control is made to shift to rich spike control in an open loop, and after the real air-fuel ratio (SVO2) transfers to the rich side, the sliding mode control in the main body 100 of the air-fuel ratio controller is resumed. |
