| 摘要 |
An adaptive same-ignition-cycle passive method is disclosed for the real-time detection and compensation of fuel volatility (or equivalently, the fuel driveability index, DI) during cold start of a multi-cylinder engine. The method detects a signature of fuel volatility on engine speed (rpm) immediately after engine starts to run. In accordance with this method, a local short-duration high-amplitude speed droop is associated with fuels of various volatility which can be detected within the first second after engine ignition while engine is in idle-neutral operation mode. The speed droop is uniquely correlated with the fuel DI value in the form of calibration tables at different temperatures. The actual fuel DI is thus detected and the optimum fuel enrichment/enleanment is quickly determined within few events after engine is flagged as running even before the transmission is engaged (vehicle still in PIN mode). Hence, optimum tradeoff between vehicle driveability and low tailpipe emissions is simultaneously achieved on-line. <IMAGE> |
