Method and apparatus for controlling fuel injection quantity into a

Abstract

Disclosed is a fuel injection quantity control system incorporated with a fuel injection pump with a solenoid-operated spill valve wherein a control signal is generated for cutting off a fuel supply to engine cylinders when a rotational phase angle of a drive shaft of the fuel injection pump is coincident with a desired spill phase angle determined in accordance with engine operating conditions. The desired spill phase angle, i.e., the opening timing of the spill valve is controlled in accordance with the rotational variations of the fuel injection pump. The desired spill phase angle is divided by unit angle corresponding to a detection period of rotational angle signals produced in accordance with the rotation of the pump drive shaft, obtaining a quotient and a remainder angle. The remainder angle is converted into a time on the basis of an engine speed. The generation of the control signal basically occurs upon the elapse of the converted time after the count of rotational angle signals is coincident with the quotient. If the engine operating condition varies immediately prior to the coincidence therebetween, the control signal is generated immediately after the coincidence or upon the elapse of a predetermined time period thereafter.