Nippondenso Co., Ltd.

Takehiro Kikuti

Akio Kobayashi

Susumu Harada

Masakazu Honda

In a computer-controlled fuel supply system of an internal combustion engine, two basic pieces of information, i.e. airflow data Q and engine speed data N, are processed by an analog operating circuit to produce a basic injection pulse signal, whose pulse width equals Q/N. The data Q/N is used by a microcomputer, when the microcomputer is in normal state, to produce a corrected injection pulse signal by using various engine parameters in the same manner as in conventional arrangements, and fuel flow is determined by the width of the corrected injection pulse signal. When malfunctioning of the microcomputer is detected, the basic injection pulse signal from the analog operating circuit is used in place of the corrected injection pulse signal from the microcomputer to determine the fuel flow. The width of the basic injection pulse signal may be lengthened when the microcomputer is in abnormal state so that air/fuel ratio is almost accurately controlled without the microcomputer.

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Oobu, Japan

Takehiro Kikuti