| 摘要 |
PURPOSE:To simplify the assembling work and to improve the controlling accuracy of the air fuel ratio by forming a reference electrode and a measuring electrode at a part of a solid electrolyte having oxygen ion conduction and providing a porous protecting layer holding a catalyst on the measuring electrode. CONSTITUTION:A reference electrode 31 (39) of porous platinum and a measuring electrode 33 (41) are formed inside and outside a solid electrolyte 25a (25b). A porous protecting layer 35 (43) (holding a catalyst) is provided surrounding the electrode 33 (41). A sensor part 37 (45) is thus formed. An oxygen sensor 17 is mounted to an exhaustion passage so that the sensor part 37 is at the upper side of the stream of the exhaustion passage than a sensor part 45. The catalysis of the protecting layer 43 holds the concentration of oxygen in an exhaust gas generally in the balanced state, and therefore the dispersion of the exhaust gas is sufficiently damped. As a result, the output characteristic of the sensor part 45 varies little. Accordingly, the controlling constant for the air fuel ratio feedback control which is executed based on the output signal of the sensor part 37 is effectively corrected by the output signal of the sensor part 45, whereby the controlling accuracy of the air fuel ratio is improved. |
