| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio sensor element having a structure where a sensing part and a pumping part is opposed through a narrow space, which never causes a short circuit between the electrode in the manufacture and has a high production yield. SOLUTION: This air-fuel ratio sensor element comprises the sensing part having a first electrode pair consisting of a reference electrode 3 and a measuring electrode 4 formed in the mutually opposed positions of the inner surface and outer surface of a solid electrolytic cylindrical base 2 and the pumping part having a second electrode pair consisting of an inner electrode 9 and an outer electrode 10 formed in the mutually opposed positions of the inner surface and outer surface of the space part 5 of a solid electrolytic layer 8 arranged on the outer surface of the measuring electrode 4 through the space part 5. The inner electrode 9 of the pumping part has an area of 10-20 mm<2> , and the area of the measuring electrode 4 of the sensing part is set to 0.3-0.8 times the area of the inner electrode 9 of the pumping part. |
