CONTROL DEVICE OF AIR-FUEL RATIO IN INTERNAL-COMBUSTION ENGINE

PURPOSE:To prevent damage by burning of a catalytic converter and deterioration of its function, by forcing a mixture to be feedback controlled to about the theoretical air-fuel ratio when a detected temperature exceeds the preset value by a signal from a temperature detecting means in an exhaust system. CONSTITUTION:A temperature sensor 15 detecting the temperature of a catalyst is mounted to a ternary catalyst 7 interposed in an exhaust passage 4, and a detection signal of the sensor 15 is input to a control circuit 8. The control circuit 8, calculating the basic amount of injection by a signal from an air flow meter 9 and an ignition coil 10, opens a fuel injection valve 6. When the temperature of the catalyst exceeds a preset value, a mixture is forced to be feedback controlled to about the theoretical air-fuel ratio. In this way, an abnormal rise of exhaust temperature can be suppressed, accordingly a catalytic converter can be prevented from its damage by burning and/or deterioration of its function due to high temperature exhaust before their occurrence.