AIR-FUEL RATIO CONTROL DEVICE, VEHICLE EQUIPPED THEREWITH AND AIR-FUEL RATIO CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device for correcting an air-fuel ratio in a cylinder to facilitate proper combustion in the cylinder without adding an air-fuel ratio sensor for detecting an air-fuel ratio in the cylinder and a pressure sensor for detecting pressure in the cylinder and a vehicle provided with it. SOLUTION: An ECU 23 detects a rotation angular speed of a crank shaft 33 at least at two points in a combustion stroke of the cylinder 34 of an engine 12 based on a signal from a crank angle sensor 39 and estimates a generation torque Tω(rotation variationΔω2) of the engine 12 based on this rotation angular speed. The ECU 23 estimates generation torques Tω(rotation variationΔω2) of the engine 12 at various air-fuel ratios with such a method and determines the air-fuel ratio at which a derivation torque Tω(rotation variationΔω2) peaks based on the plurality of estimated generation torques Tω(rotation variationΔω2) and corrects the air-fuel ratio in the cylinder 34 for a target air-fuel ratio. COPYRIGHT: (C)2009,JPO&INPIT