| 摘要 |
PURPOSE:To keep temperature in an air-fuel ratio sensor constant all the time as well as improve the accuracy of air-fuel ratio detection by altering the impressed voltage of a heater, heating an air-fuel ratio detecting element member, with any one of a target air-fuel ratio of driving state quantity of an engine, temperature state quantity and car speed. CONSTITUTION:A detected value of an air-fuel ratio sensor 3 is inputted into an air-fuel ratio controller 50 together with those of an intake air quantity sensor 5, an intake air temperature sensor 6, a throttle opening sensor 8, an engine speed sensor 9 and a cooling water temperature sensor 10. The air-fuel ratio controller 50 finds a heater reference voltage and a correction factor on the basis of engine speed and load (intake air quantity/engine speed), intake air temperature and target air-fuel ratio, and it sets a heater demand voltage. Then, it controls the impressed voltage of a heater 32, heating an air-fuel ratio detecting element part 31 of the air-fuel ratio sensor 3, via an amplifier 50b and a transistor TR1. This impressed voltage is fed back via an analog-to-digital converter 50E. |
