Air-fuel ratio control system for internal combustion engines

摘要

An air-fuel ratio control system is disclosed for controlling the air-fuel ratio of a mixture supplied to an engine on one side of stoichiometric. The system comprises a sensor for detecting the arrival of the inlet air-fuel ratio at its stoichiometric level and fuel supply means for supplying a controlled amount of fuel to the intake system of the engine. Control means is associated with the sensor for providing first and second control signals to the fuel supply means so as to control the amount of fuel supplied therethrough. The first control signal occurs to cause the inlet air-fuel ratio to vary toward the stoichiometric level and the second signal occurs for a predetermined period of time after the inlet air-fuel ratio arrives at the stoichiometric level to cause the inlet air-fuel ratio to vary away from the stoichiometric level.