摘要 |
A gas sensor includes a sensor element and a porcelain insulator in which the sensor element is retained. The sensor element includes a measurement gas electrode, an electric lead extending from the measurement gas electrode, a dense protective layer covering the lead, and a porous protective layer disposed on the dense protective layer to cover the measurement gas electrode. The dense protective layer protrudes from an end of the porous protective layer by a distance of 5 mm or less, thereby ensuring the mechanical strength of the porous protective layer to minimize physical separation of the lead from the solid electrolyte layer. The base end of the porous protective layer lies inside porcelain insulator, thereby covering the whole of a portion of the sensor element exposed directly to the measurement gas with the porous protective layer to minimize the separation of the lead.
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