| 摘要 |
PURPOSE:To enable feedback control of air-fuel ratio with high accuracy in a device wherein an air-fuel ratio sensor has an oxygen concentration detecting element and a heater for heating the element to a specified temperature. CONSTITUTION:An air-fuel ratio sensor 8, arranged on a discharge pipe 7, detects an air-fuel ratio through a specified component in exhaust gas, and has an oxygen concentration detecting element and a heater for heating the element to a specified temperature. Output signals from the air fuel ratio sensor 8 and sensors 2, 3, 6, 9 which detect other operation conditions are input to a control circuit 10, and an injector 4 is feedback-controlled so as to set the air-fuel ratio to a specified value. In such an air-fuel ratio control device, a constant voltage circuit which supplies a constant voltage to the heater housed in the air-fuel ratio sensor 8 is provided on the control circuit 10. Output error of the air-fuel ratio sensor 8 is thus eliminated, and feedback control of the air-fuel ratio with high accuracy is enabled. |
