Fuel-injection control system for an internal combustion engine

摘要

A fuel-injection control system for an internal combustion engine capable of ensuring the stable and proper backup operation of the engine in case of a failure of an intake-air sensor without suffering from any substantial influence from the amount of intake air flowing through a bypass conduit which bypasses a part of intake air in an intake passage across a throttle valve. The fuel-injection control system comprises: the intake-air sensor for detecting the flow rate or the pressure of intake air sucked into the engine; a throttle-opening sensor adapted to generate an output signal representative of the opening degree of the throttle valve; a temperature sensor adapted to generate an output signal representative of the temperature of an engine coolant; an engine RPM sensor adapted to generate an output signal representative of the RPMs of the engine; and a control unit adapted to receive output signals of the sensors for controlling the operations of the fuel injection valves on the basis of the information on engine operating conditions obtained from the sensors in a manner such that when the intake-air sensor fails, the amount of fuel to be injected from the fuel injection valves is determined on the basis of the opening degree of the throttle valve detected by the throttle-opening sensor, the temperature of the engine coolant detected by the temperature sensor, and the RPMs of the engine detected by the engine RPM sensor.