| 摘要 |
PURPOSE:To provide a higher degree of freedom in a control range with respect to the feedback control of an air to fuel ratio and simplification of the construction wherein an oxygen sensor exhibiting two kinds of characteristics is mounted in a detection part by forming said sensor into one unit. CONSTITUTION:Electrodes 7a, 7b, 7c, 7d are provided in both side parts of the parts which constitute a closed chamber A of a ceramic sintered body 6 and face to each other. The electrodes 7a, 7b, 7c, 7d consisting of, for example, platinum plated externally with gold are used in order to decrease their catalytic effect. Electrode protective layers 8a, 8b, 8c, 8d consisting of porous ceramics cover the top surfaces of the respective electrodes. Diffusion pores 5a, 5b are provided to the electrode protective layers, the respective electrodes and the ceramic sintered body. A voltage is impressed through a resistance at both terminals of the electrodes 7c, 7d, and the current to be conducted is so controlled that the electromotive force induced in the electrodes 7a, 7d is maintained constant by regulating the voltage. The platinum Pt electrodes 9a, 9b provided on both surfaces in the part of the open chamber B in the body 6 constitute a sensor for detecting a theoretical air to fuel ratio. |
