Air Fuel Ratio Control Device

Abstract: Provided is an air-fuel ratio control device that can perform accurate air-fuel ratio feedback control regardless of variation in resistance values due to manufacturing tolerances and changes over time in an oxygen sensor. This air-fuel ratio control device comprises: an excess ratio calculation unit (25) that, using a data map that associates a plurality of air excess ratio values ? with temperatures T and voltage values VHG of a detection unit of a resistance-type oxygen sensor, calculates an air excess ratio ?; a lookup table that associates rich-side threshold values RREF and lean-side threshold values LREF with the temperatures T; a characteristics examination unit (40) that acquires a peak value of the voltage values VHG by setting a target air excess ratio ?cmd to a stoichiometric neighborhood and examines whether the peak values are in a rich region, a stoichiometric region, or a lean region; and a calibration unit (41) that calibrates the data map and the lookup table using an affine transformation procedure so that the peak value according to the examination fits the rich-side threshold value RREF and the lean-side threshold value LREF.

Patent Information

Applicants

Inventors

Specification

Documents

Application Documents