| 摘要 |
PURPOSE:To prevent an oxygen sensor from the variation with time caused by dust, etc. by impressing a voltage between the inner electrode and an outer second electrode, while short-circuiting an electrode in a reference chamber and an outer first electrode, and measuring the current flowing thereat. CONSTITUTION:A solid electrolyte 10 such as zirconia has a plane plate shape. An electrode 12 is formed on one surface of the electrolyte and two electrodes 18, 20 are formed on the other surface respectively. The electrodes are porous and air permeable. The electrode 12 is covered with a cover 30, isolated from outer air, and forms a space 32 enclosed tightly. The electrodes are connected with a source 50 and an ammeter 52. Oxygen molecules in the reference chamber 32 are ionized at the interface of the electrode 12 and the electrolyte 10 by a current I. The oxygen ions are converted to oxygen molecules at the electrode 18. Thus, the oxygen in the chamber 32 is pumped out, and the oxygen partial pressure difference is caused between the gases in the chamber 32 and the circumference. The oxygen diffused into the chamber 32 due to the partial pressure difference is pumped out immediately, and the pumping current at this time indicates the oxygen concn. of the circumference. |
