Exhaust gas recirculation control system for a diesel engine and control method therefor

摘要

In an exhaust gas recirculation control system in which a fuel injection quantity is determined on the basis of engine speed and engine load, a throttle-closed range is determined on the basis of engine speed and fuel injection quantity. An exhaust gas recirculation control valve has an electromagnetically operable valve actuator, the duty cycle of which is controlled by a control signal. The duty cycle of the valve actuator is variable in accordance with engine operational condition either in or out of the throttle-closed range. An electromagnetically operated actuator is associated with the throttle valve for controlling the operation of the latter. The actuator is operable between a throttle-open position and a throttle-closed position to operate the throttle valve depending on whether the engine operation conditions are within or out of the throttle-closed range.