| 摘要 |
A bi-fuel engine has a gaseous fuel mode engine start strategy that delivers a calibrated amount of supplemental gasoline during engine starting and initia l gaseous fuel engine runs. The strategy is embodied in an algorithm employing variables including start of supplemental gasoline fueling, end of supplemental gasoline fueling, ramp-in period of supplemental gasoline fueling, ramp-out period of supplemental gasoline fueling, and the fraction of supplemental gasoline fuel to be delivered relative to that which is normally delivered during a conventional gasoline start. The algorithm differentiates between hot and cold engine starts for determining how much supplemental gasoline is to be delivered during gaseous fuel starts, wherein hot starts occur before substantially complete diffusion of gaseous fuel in the intake system, and cold starts occur after diffusion of gaseous fuel in the intake system is substantially complete. Time required for substantially complete diffusion depends on geometry of the intake system. The gaseous fuel start strategy allows for modification (i.e. calibration) of criteria used for hot and cold start determination for different vehicles. |
