Hitachi, Ltd.

Goji Matsumoto

Shoichi Sakai

Futoshi Ichiyanagi

Akira Uchikawa

Junji Onozuka

An oxygen sensor includes a base body portion; and a plurality of function layers laminated on a surface of the base body portion. The function layers includes a solid electrolyte layer adapted to conduct oxygen ions; a reference electrode layer located on a base body portion side of the solid electrolyte layer; a sensing electrode layer located on the opposite side of the solid electrolyte layer to the reference electrode layer; a heater portion adapted to activate the solid electrolyte layer by heating; and a gas diffusion layer formed between the reference electrode layer and the base body portion, and adapted to diffuse a reference gas within the gas diffusion layer. The gas diffusion layer is formed to have a porosity indicating a limit current value ranging between 60 &#x3bc;A and 200 &#x3bc;A. The limit current value is a value of a current flowing between the reference electrode layer and the sensing electrode layer when the current flowing therebetween becomes substantially constant during the process of bringing a voltage applied therebetween higher.

Oxygen sensor

An oxygen concentration detecting element including a base member made of an electrically insulating material, a heater disposed on an outer surface of the base member, the heater being adapted to generate heat upon being energized, and an oxygen detecting unit disposed in an offset position on the outer surface of the base member in which the oxygen detecting unit is prevented from overlapping with the heater, the oxygen detecting unit including a solid electrolyte layer and a pair of electrodes between which the solid electrolyte layer is disposed.

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Gunma, Japan

Goji Matsumoto