Gas sensor and manufacturing method therefor
AssigneeKoa Corporation
InventorsTetsuro TANAKA, Kenichi IGUCHI, Ken TAKAHASHI, Chika ITO
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Abstract
A sensor element has a cross-sectional area that increases either uniformly or gradually from a positive (+) electrode side toward a negative (−) electrode side, thereby leading a hot spot, which attempts to move to the negative electrode side, to a lower resistance side. A position that is at nearly equal distances from paired electrodes formed on either end of the sensor element is set as a hot spot generating position, so as to avoid damage to the electrodes due to heat emitted by the hot spot.
Claims11
A gas sensor made from a ceramic sintered body for detecting as gas concentration, either change in an electric current value or change in a resistance value measured when a voltage is applied to a sensor element, wherein
- the sensor element has a shape in which a cross-sectional area changes from one electrode side toward the other electrode side of paired electrode parts formed on either longitudinal end.
A manufacturing method for a gas sensor made from a ceramic sintered body for detecting as gas concentration, either change in an electric current value or change in a resistance value measured when a voltage is applied to a sensor element;
- comprising the steps of:
- manufacturing a green sheet from slurry formed by mixing together raw materials of the sensor element;
- manufacturing a ring-shaped first green sheet by punching out the green sheet so as to form a punched hole having a predetermined diameter;
- manufacturing a ring-shaped second green sheet by forming belt-like shaped electrodes along periphery of the punched hole of the first green sheet and a ring-shaped outer periphery of the first green sheet;
- manufacturing a ring-shaped laminated body by coaxially stacking a plurality of the first green sheet with the second green sheet as a top surface;
- cutting the laminated body along a plurality of diametral virtual lines of the ring-shaped laminated body that is formed by rotating around the axis of the ring-shaped laminated body every fixed angle in the circumferential direction;
- and
- baking a sensor element divided into individual pieces through said cutting, and forming paired electrodes on either end part in the longitudinal direction.
A manufacturing method for a gas sensor made from a ceramic sintered body for detecting as gas concentration, either change in an electric current value or change in a resistance value measured when a voltage is applied to a sensor element, comprising the steps of:
- manufacturing a long green sheet from slurry formed by mixing together raw materials of the sensor element;
- manufacturing a sensor element piece with a nearly trapezoidal shape, in a planar view, by cutting the green sheet in a zigzag shape at predetermined intervals in a direction crossing a longitudinal direction of the green sheet;
- and
- baking the sensor element piece and forming paired electrodes on either end part in the longitudinal direction.
Dependencies are inferred from the claim text.