| 摘要 |
PURPOSE: To prevent drop of the sensitivity in a susceptible region for a toxic component to be measured in an exhaust gas by furnishing a measuring element with a gas-tight covering layer having a stop-shaped opening. CONSTITUTION: A pump cell 10 has a solid electrolyte carrier 13, for example made of zirconium oxide, and in the carrier 13 a thermal conductive path 25 is provided as embedded in a gas passage 23 and heater insulation part 24. On the carrier 13, an inner pump electrode 11 is installed, while an outer pump electrode 12 is installed in the gas passage 23. On a porous insulating layer 15, measuring electrodes 18, 19 are furnished, for example made of platinum- thermet compound. A gas-tight covering layer 16 is installed on the insulating layer 15, and a stop-shaped opening 17 is formed on the electrodes 18, 19, wherein a metal oxide layer 21 consisting of SnO2 , etc., is provided in the opening 17. The covering layer 16 is formed from ZrO2 , Al2 O3 , etc., and it is possible to regulate the oxygen partial pressure by the covering layer 16 in a susceptible region of a measuring element 20. |
