| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas sensor capable of more accurately measuring the concn. of nitrogen oxide. SOLUTION: In a gas sensor 1, a microcomputer 43 controls the voltage applied to a heater 27 so that the temp. of a second oxygen pump cell 15 becomes 650-770 deg.C and also controls the voltage applied to a heater 25 so that the temp. of a first oxygen pump cell 11 becomes higher than the temp. of the second oxygen pump cell 15 by 80-100 deg.C. By this constitution, the increase of a second pump current IP2 caused by the presence of residual oxygen or steam incapable of being sufficiently pumped out by the first oxygen pump cell 11 can be suppressed to a negligible degree. |
