Electronically-controlled fuel injection system for internal combustion

Abstract

An electronically-controlled fuel injection system for an internal combustion engine having odd numbers of cylinders, in which the quantity of fuel supplied to the engine cylinders is regulated by the duration of pulses of a fuel injection pulse signal applied to solenoid-operated fuel injection valves, and two fuel injection pulses are generated in each operating cycle of the engine in synchronism with the revolution of the engine. In the system, the frequency of an ignition signal generated by an ignition unit for the engine is divided by the number of cylinders of the engine to provide a first pulse signal and a second pulse signal. The phase of each pulse of the second pulse signal lags behind that of the first pulse signal by n ignition pulse intervals where n is a multiple number of the half of the number obtained by subtracting unity from the number of cylinders of the engine. A third pulse signal is further generated in which the fall time of each pulse is delayed by the half of one ignition pulse interval relative to the fall time of the corresponding pulse in the second pulse signal. The fuel injection pulse signal is generated in synchronism with the fall time of the pulses of the first and third pulse signals.