| 摘要 |
PURPOSE:To improve the detection accuracy by separating the oxygen ion carrying part from the electromotive force generating part through the flowing of the bias current. CONSTITUTION:A solid electrolyte 14 is arranged among the measuring electrodes 10a and 10b made of catalytically active conductive material, the measuring electrode sections and the reference electrodes 12a and 12b made of close solid electrolyte 11 and the reference electrode section made of a solid electrolyte 13. With such an arrangement, in the rich region, the catalytic reaction of unburned gas is caused on the surface of the electrodes 10a and 12a contacting exhaust gas, and in the electrodes 10b and 12b, the oxygen in the exhaust gas diffuses through the porous solid electrolytes 12 and 13. The bias current from the constant current source allows the oxygen ion from the electrode 10a to increase the partial pressure of oxygen whereby the oxygen diffused in the electrode 12b is deprived as ion. As a result, the partial pressure of the oxygen rises in the electrode 10b and lowers in the electrode 12b through the solid electrolyte 14, so that the electromotive force between the electrodes 10b and 12b is extracted to detect the rich condition. As no bias current flows in the electromotive force generating part, massproduction of detectors uniform in the characteristics is possible without being affected by dispersion of the resistance value during the production. |
