| 摘要 |
PURPOSE:To miniaturize a sensor by covering an electrode with glass to form a sealing part and utilizing thermal expansion coefficient at a time of sensing and forming the space between the electrode and the sealing part. CONSTITUTION:A gas diffusing hole 11 is bored in the nearly central part of a solid electrolyte 10. The porous platinum electrodes 12, 13 utilized for a cathode and an anode are formed on the surface and the rear of the electrolyte 10. A sealing part 14 made of glass is formed on the surface of this electrolyte 10 so as to cover the electrode 12. When this oxygen sensor is placed in the atmosphere to be measured and heated to perform sensing treatment, a fine space is formed between the sealing part 14 and the electrode 12 because the thermal expansion coefficient of the sealing part 14 is larger than the thermal expansion coefficient of the electrode 12. When voltage is impressed between the electrodes 12, 13 so that this electrode 12 is made negative polarity, oxygen ion is transferred toward the electrode 13 from the electrode 12 and current is allowed to flow between the electrodes 12, 13. Even when voltage is increased, current is held at constant value. The concn. of gaseous oxygen in the atmosphere to be measured is obtained by measuring the limiting current in this flat region. |
