초록 ▼

An air-fuel ratio control apparatus for an internal combustion engine has an oxygen sensor, a first operational means, a second operational means, a maximum and minimum setting means, an air-fuel ratio correcting means, a maximum and minimum magnifying means, and a maximum and a minimum returning me

An air-fuel ratio control apparatus for an internal combustion engine has an oxygen sensor, a first operational means, a second operational means, a maximum and minimum setting means, an air-fuel ratio correcting means, a maximum and minimum magnifying means, and a maximum and a minimum returning means. When an air-fuel ratio learning value calculated by the second operational means reaches a maximum or minimum limit set by the maximum and minimum setting means, an air-fuel ratio feedback correction value is measured for a predetermined time. The maximum and minimum magnifying means increases the maximum or decreases the minimum limit of the air-fuel learning value in response to a deviation of fuel injection amount from a fuel injection amount requested for maintaining a target air-fuel ratio. The maximum and minimum returning means returns the maximum or minimum limit of the air-fuel ratio learning value to a predetermined basic maximum or minimum limit, when a predetermined condition continues for a predetermined time. An emission condition, or an emission amount exhausted from the internal combustion engine, is improved by the above-mentioned control.

대표청구항 ▼

1. An apparatus for controlling an air-fuel ratio in an internal combustion engine comprising:an oxygen sensor in an exhaust passage of the internal combustion engine for detecting a concentration of oxygen in exhaust gas from said internal combustion engine; a first operational means for calculatin

1. An apparatus for controlling an air-fuel ratio in an internal combustion engine comprising:an oxygen sensor in an exhaust passage of the internal combustion engine for detecting a concentration of oxygen in exhaust gas from said internal combustion engine; a first operational means for calculating an air-fuel ratio feedback correction value based on a value outputted by said oxygen sensor so that an actual air-fuel ratio in said internal combustion engine is equal to a target air-fuel ratio; a second operational means for calculating an air-fuel ratio learning value so that the air-fuel ratio feedback correction value is within a predetermined range, the air-fuel ratio learning value being different from the air-fuel ratio feedback correction value; a maximum and minimum setting means for setting a maximum limit and a minimum limit of the air-fuel ratio learning value; an air-fuel ratio correcting means for correcting a fuel injection time of a fuel injection valve in an intake passage of said internal combustion engine based on the air-fuel ratio feedback correction value calculated by said first operational means and the air-fuel ratio learning value calculated by said second operational means; and a maximum and minimum magnifying means for increasing the maximum or decreasing the minimum limit of the air-fuel ratio learning value by stepping degrees in response to a deviation of fuel injection amount, injected by the fuel injection valve, from a fuel injection amount requested for maintaining the target air-fuel ratio after the air-fuel ratio learning value reaches the maximum or minimum limit.