A Study of Control Strategies of PFI Engine during Cranking and Start for HEVs

Engine off at Idle is one of the fuel saving strategies for HEVs, and there´re more start and stop events in HEVs than traditional cars at city driving condition, therefore the control strategies during cranking and start are very important for HEVs. Additionally, the engine start process of HEVs is different to that of traditional cars, especially in the cranking and startup process, so the engine start strategies should be modified for HEVs. In this paper, the authors constructed a test bench to simulate the quick start process of HEVs, and investigated the control strategies under different cranking speeds. With various cranking speeds, the fuel metering strategy, the ignition angle and the injection timing are all different from a normal engine start, especially for the first firing cycle.