| 摘要 |
PURPOSE:To attain sensors with good linearity even in the vicinity of the equivalent point of combustible gas and O2 by a construction wherein catalytic performance of Pt forming electrodes of the sensor having diffusion fine holes and having an electrode pair serving as an O2 pump as well as another electrode pair for sensing is set not greater than a specific value. CONSTITUTION:Fine holes are bored at the centers of discs made of ZrO2 sintered material stabilized with Y2O3, which are disposed on both sides of a cylindrical spacer. Platinums 31a, 31b, 32a and 32b are evaporated on both sides of the respective discs. Then, thin plated films of Au or Pt-Au alloy are bonded on the surfaces of the respective platinums to form a sensor for measuring O2 contained in exhaust gas mixed with combustible gas without a need of reference atmospheric pressure gas. Voltage is applied through a feedback amplifier between one electrode 32b and the other electrode 31a of this sensor, thereby to detect O2 density. Catalytic performance of the Pt electrodes which allow combustible gas to burn at the Au or Pt-Au thin films bonded on the platinum electrodes, is set less than the value of Au 20% containing Pt. by so doing, it becomes possible to attain the O2 gas sensor which has good linearity even in the vicinity of the equivalent point of combustible gas and O2. |
