Nippondenso Co., Ltd.

Kazunori Kishita

Masakazu Ninomiya

Toshiaki Kikuchi

Noriaki Kurita

Jun Ozeki

A relation with output characteristic of an oxygen density sensor corresponding to a deviation of an air fuel ratio of a mixed gas supplied actually to an internal combustion engine from a desired air fuel ratio is stored beforehand in an air fuel ratio controller of the present invention. Then, the air fuel ratio deviation is computed correspondingly to an actual output of the oxygen density sensor according to the stored relation, and an air fuel ratio controlled variable is corrected according to the computed air fuel ratio deviation, thereby controlling the air fuel ratio to the desired air fuel ratio. Further, a change in output characteristic of the oxygen density sensor to the air fuel ratio is detected, then the output characteristic of the oxygen density sensor stored beforehand is corrected according to the detection result, and thus if the output characteristic of the oxygen density sensor fluctuates due to a deterioration arising on the oxygen density sensor, the air fuel ratio controlled variable will be decided in consideration of the fluctuation.

Air-fuel ratio controller for internal combustion engine

An apparatus for controlling a quantity of fuel injected into an internal combustion engine comprises a sensor for detecting atomspheric pressure, a sensor for detecting a load condition of an internal combustion engine, and an electronic control device including a microprocessor. The CPU functions to perform the processing steps including: step of setting a reference fuel injection quantity in accordance with a load condition of the engine, step of detecting a transient condition of the engine, step of setting a transient correction value in accordance with the transient condition of the engine, step of correcting the transient correction value to be decreased as the atmospheric pressure decreases, and step of setting a quantity of injection fuel supplied to the engine in accordance with the set value of the reference fuel injection quantity and the corrected transient correction value, whereby a deviation of an air fuel ratio from an appropriate value can be prevented even under a transient condition where atmospheric pressure varies.

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Kariya, Japan

Kazunori Kishita