| 摘要 |
PURPOSE:To prevent shifting of an air-fuel ratio to a lean/rich side by amending an output of a converting/amplifying means which converts a pump current, supplied so as to set the voltage of an oxygen sensor to be a specified value, into a voltage and amplifies it, and performing air-fuel ratio control according to the amended result. CONSTITUTION:An air-fuel ratio detector is composed of a wide area air-fuel ratio sensor 80 and an air-fuel ratio detecting circuit 81, which air-fuel ratio sensor 80 has an oxygen sensor 82 to generate electromotive force according to oxygen concentration difference between reference gas and exhaust gas, and an oxygen pump 83 to supply pump current for setting the output voltage to be a specified value. The air-fuel ratio detecting circuit 81 is composed of an electromotive force difference detecting circuit 84, a pump current supplying circuit 85, a current/voltage converting circuit 86, and a voltage amplifier 87. An air-fuel ratio signal after sensor activation is amended according to an output deviation of the voltage amplifying circuit 87 when the temperature of the sensor 80 fails to reach a specified activation temperature and the pump current is stopped. Then air-fuel ratio control is carried out according to the amended air-fuel ratio signals. |
