| 摘要 |
PROBLEM TO BE SOLVED: To start a detection operation in early stages, by using a detection signal of an oxygen sensor part, when an oxygen pump part is un-activated. SOLUTION: An oxygen sensor part 8 between electrodes 9, 10 and an oxygen pump part 12 between electrodes 13, 14 are installed in a sensor case 2 of an air-fuel ratio sensor 1, and these parts are heated and activated by a heater 16. And, a signal output processing circuit 18 outputs an air-fuel ratio signal VOUT. And besides, a signal change-over switch 19 outputs a temporary oxygen concentration signal Vt between the electrodes 9, 14, when the oxygen pump part 12 is un-activated, and outputs the air-fuel ratio signal VOUT, after the oxygen pump part 12 is activated. Hereby, a control unit 20 can start air-fuel ratio control in early stages by using the temporary oxygen concentration signal Vt, even if the oxygen pump part 12 is in the un-activated state. |
