LAUSR

For the multi-cylinder gasoline engine, the consistency among cylinders is an important index to affect the engine emission and the engine power. In this paper, an individual cylinder air-fuel ratio (A/F) control method for a fourcylinder camless engine with the electromagnetic valve train (EMVT) was proposed to reduce the imbalance of engine torque. An individual cylinder A/F estimation algorithm with a single universal exhaust gas oxygen (UEGO) sensor based on fading Kalman filtering was introduced. Four proportional-integral feedback controllers were built to regulate the individual A/F by adjusting the intake valve closing (IVC) timing of each cylinder independently based on the EMVT. The effectiveness of the proposed estimation and control approach was validated by co-simulation of GT-Power and Simulink. The results showed that the proposed estimation method could accurately estimate the individual cylinder A/F, and the maximum estimation error under steady state condition was less than 1 %. With the feedback control, both the individual A/F imbalance and the cylinderto- cylinder torque generation imbalance were decreased.