Research of Working Mode Conversion Based on GDI Engine

This paper designs the control strategy of working mode conversion from stoichiometric homogeneous mixture to lean homogeneous mixture. First of all, after the types and parameters of electric hardware were selected in this system, a complete circuit layout of engine control system was designed, which used microcontroller named MC9S12XDP512 as control chip and the test bench was built. Then, we adjust the fuel injection pulse width and throttle opening to realize lean burn (lambda = 1.4) of torque being 40N.m at speed of 2500 r / min, and adjust injection timing to find the best injection timing which is 350 crank angle degree, and adjust the ignition advance angle to find the best ignition advance angle which is 13 crank angle degree. Finally, the work mode conversion was completed by the optimal parameters linear interpolation, reducing the fuel injection pulse width and increasing the throttle opening at the same time.