Method and system for estimating air/fuel ratio of an engine having a non-heated fuel vaporizer

Abstract

A method and system for estimating air/fuel ratio of an internal combustion engine having a fuel vaporizer device calculates the rate of fuel evaporation based on temperature of the vaporizer device to estimate air/fuel ratio during a cold-start. In one embodiment, a temperature of the fuel vaporizer device is determined directly by an appropriate sensor. In another embodiment, the temperature is determined using a transient heat transfer model based on the air flow rate through the device and the exit temperature of the air/fuel mixture. The temperature is used to determine the amount of energy entering the fuel vaporizer device as well as the amount of energy leaving the fuel vaporizer device so as to determine the amount of fuel vaporized by the fuel vaporizer device. The air/fuel ratio is then estimated based on the amount of fuel vaporized.

Dependencies are inferred from the claim text.