Air-fuel ratio control device for engine

Abstract

Abstract PURPOSE:To maintain an air-fuel ratio in all operational regions at a theoretical air-fuel ratio by providing means for estimating a learning factor in other area of a learning correction factor map according to a deterioration characteristic of a hot wire air flow meter. CONSTITUTION:In an ECU 21 for controlling injectors 8 located in suction passages, basic fuel injection pulse width computing means 22 computes a basic injection pulse width according to outputs from a hot wire air flow meter 11 and a crank angle sensor 18, and feedback correction quantity computing means 24 computes an air-fuel ratio feedback correction quantity according to an output from an exhaust sensor 19. A learning correction factor map 26 sets a learning correction factor for each operational region according to an engine speed and the basic injection pulse width, and learning correction factor computing means 30 updates the correction factor in the map 26 according to an output from the computing means 24. Further, estimated learning correction factor computing means 31 estimates a learning factor in other area of the map 26 from a suction air quantity in a basic area of the map 26 and a correction factor obtained by the computing means 30, according to a deterioration characteristic of the air flow meter 11.

Inventors

• 👤 Masaru Murata
• 👤 大 村田

Bibliographic Details