Abstract
Some of injected fuel form liquid film on the internal wall of intake port or cylinder and will evaporate in later cycles. In order to achieve an optimal air-fuel ratio control at cold-start cycles, a quantitative, transient fuel liquefying and evaporating progress has to be estimated. In this study we have developed the method to calculate the amount of fuel-film at each cycle bymeasurement of transient intake air flow and transient concentration of exhaust gas component (CO, CO2, and THC).With this method we have made a statistical model which can estimate the mass of fuel-film at any condition. Then we practically applied the model to the feed-forward injection control to keep stoichiometric air-fuel ratio at cold-start cycles.
