Design of a quick-startup air-fuel ratio (A/F) sensor for automobiles is examined. The sensor detects oxygen and/or incomplete-combustion gas concentration in exhaust to find the A/F of engine operations. We propose a compact structure sensing part which is directly stacked on a heater, where porous and dense zirconia layers are combined without inner gas chambers, We report, in this paper; the basic function of each zirconia layer for further studies of the proposed sensor: (a) porous zirconia layer stacked on a heater showed clear limiting-currents of oxygen pump in several A/F conditions. The limiting-currents were obtained near the pumping voltage of 0.5 V. The currents were 1-3 mA in air depending on the gas transparency of the porous zirconia samples; (b) one of the platinum electrodes attached to the dense zirconia layer was designed to act as a built-in standard of oxygen concentration. An additional current source was utilized to keep oxygen ion current. We confirmed that the electrode maintain substantially constant amount of oxygen in a wide A/F range of 10.5-30.
Limiting-current type air-fuel ratio sensor using porous zirconia layer without inner gas chambers: proposal for a quick-startup sensor
Sensors and Actuators, B, Chemical ; 73 , 1 ; 40-48
2001
9 Seiten, 23 Quellen
Article (Journal)
English
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