Patent ID: 7739025

Claim:
An estimation apparatus of an alcohol component amount in fuel, the estimation apparatus comprising: an exhaust air-fuel ratio detection unit, configured to detect an air-fuel ratio of exhaust discharged from an engine; a feedback correction value setting unit, configured to set a feedback correction value by feedback control based on the detected air-fuel ratio; a learning unit, configured to execute learning control for setting a learning value of the air-fuel ratio based on the set feedback correction value; an estimation condition satisfaction determination unit, configured to determine whether or not a fuel component amount estimation condition is satisfied; a learning prohibition unit, configured to prohibit the learning unit from executing the learning control and retain the learning value, which is set just before prohibiting, as a fixed learning value which is a fixed value, when the estimation condition satisfaction determination unit determines that the fuel component amount estimation condition is satisfied; an air-fuel ratio correction amount computation unit, configured to compute a correction amount of the air-fuel ratio based on the feedback correction value and the fixed learning value, when the estimation condition satisfaction determination unit determines that the fuel component amount estimation condition is satisfied; an injection correction value change rate computation unit, configured to compute a change rate of the correction amount; an alcohol component correction value computation unit, configured to compute an alcohol component correction value based on the change rate; and an alcohol component amount estimation unit, configured to estimate the alcohol component amount in the fuel based on the alcohol component correction value.