Alternative fuel concentration estimating system, vehicle comprising alternative fuel concentration estimating system, and alternative fuel concentration estimating method

摘要

An ECU is used in a motorcycle including an engine E, which combusts in a combustion chamber a blended fuel in which gasoline and ethanol are blended, and a fuel injection device for injecting a fuel with a predetermined fuel injection amount such that an air excess ratio in the combustion chamber is a first predetermined value when an ethanol concentration of the blended fuel is zero. The ECU executes O₂ feedback control based on an O₂ concentration derived from an output of an O₂ sensor. Further, the ECU calculates an actual fuel compensation ratio by dividing a fuel injection amount after the O₂ feedback control by a predetermined fuel injection amount, and estimates the concentration of the alternative fuel based on this actual fuel compensation ratio and a first predetermined value stored in the ECU.