Air-fuel ratio control device for internal combustion engine for outboard motor, air-fuel ratio control method, and program product

摘要

An air-fuel ratio control device has an open loop controller which controls an air-fuel ratio to be a target air-fuel ratio, a feedback controller that shifts the target air-fuel ratio to a logical air-fuel ratio, and feedback controls the air-fuel ratio to be the logical air-fuel ratio by using a feedback correction coefficient determined based on an output of an O2 sensor, an average value calculator that calculates an average value of the feedback correction coefficient when the output of the O2 sensor reverses from a lean side to a rich side and from the rich side to the lean side in a feedback control by the feedback controller, and a learned value calculator that calculates a learned value based on the average value at a time when the average value calculated by the average value calculator becomes substantially constant.

主权项

1. An air-fuel ratio control device which controls an air-fuel ratio of an internal combustion engine for an outboard motor provided with an O2 sensor, which is disposed in an exhaust system of the internal combustion engine and varies in output characteristics in a vicinity of a logical air-fuel ratio, the air-fuel ratio control device comprising:
an open loop controller that controls the air-fuel ratio to be a target air-fuel ratio based on an operating state of the internal combustion engine and a learned value; a feedback controller that shifts the target air-fuel ratio to a logical air-fuel ratio from a state that the target air-fuel ratio is controlled to be a predetermined air-fuel ratio on a lean side by the open loop controller, and feedback controls the air-fuel ratio to be the logical air-fuel ratio by using a feedback correction coefficient determined based on an output of the O2 sensor; an average value calculator that calculates the average value of the feedback correction coefficient when the output of the O2 sensor reverses from a lean side to a rich side and from the rich side to the lean side in the feedback control by the feedback controller; and a learned value calculator that calculates the learned value based on an average value at a time when the average value calculated by the average value calculator becomes substantially constant, wherein the average value calculator calculates the average value by using a predetermined number of past feedback correction coefficients when the output of the O2 sensor reverses from the lean side to the rich side and from the rich side to the lean side.