Abstract: An oxygen sensor has an oxygen sensor element in the form of an elongated plate having an oxygen detection section at the end of said oxygen sensor element. The oxygen detection section generates electromotive force between electrodes according to oxygen concentration or varies electrical resistance. Chamfering is applied to ridges formed parallel to the lengthwise direction of the oxygen sensor element which is exposed to gas to be measured. According to this sensor, cracks do not occur. Therefore, oxygen concentration detecting function is not damaged even when the oxygen sensor element is thermally stressed.

Abstract: A continuous extrusion method of manufacturing ceramic honeycomb structures with the aid of a screw type vacuum extruding machine is disclosed. The method is characterized by making the temperature at the outer periphery of the ceramic raw material batch located in the rear of the extrusion die not lower than the temperature at the center portion of the batch.