摘要 |
The invention provides an air/fuel ratio sensor, including an electrochemical sensor cell and an electrochemical pump cell, which shows both a quick response and a stable limiting current. This is realized by limiting the ratio of the area a of a region A to the area b of a region B on the inner electrode of the electrochemical sensor within a specified range, 0 < a/b </= 0.1. Here, the region A corresponds to a region C within a 0.5 mm distance from the end of the gas diffusion hole except on the 0.5 mm distance line on the inner electrode of the electrochemical pump cell, and the region B corresponds to a region D or the complement of the region C on the inner electrode of the electrochemical pump cell. |