Electrochemical oxygen sensor, particularly for exhaust gases from combustion engines
AssigneeRobert Bosch GmbH
InventorsHerbert Csanitz, Helmut Weyl
Life of this patent
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Abstract
To prevent signal degradation of a sensing element, which may be a potentiometric or a polarographic sensor, having a reference electrode exposed to ambient air, the reference electrode (22) is placed within a chamber (21) which has included therein granules (39) of a material inert with respect to oxygen and having a surface hardness at least as hard as the reference electrode (22) so that, upon subjection of the sensor, when coupled to the exhaust system of an internal combustion engine, to vibrations, shocks and jolts, the granules will move in the chamber, rub against the electrode, and hence keep the electrode surface activated and free from contamination which may have penetrated with ambient air.
Claims14
In combination with an exhaust system of an internal combustion engine having an exhaust component (E) subject to vibration,
- an electrochemical sensor to determine the oxygen content of gases, particularly of exhaust gases from an internal combustion engine, said sensor having
- a body (11) of solid electrolyte material;
- a layer-like porous measuring electrode (14) applied to a first surface region of the body;
- means including another surface region of the body defining a hollow chamber (21);
- a layer-like reference electrode (22) located on said other surface region of the body and positioned within the hollow chamber (21), said hollow chamber being open to ambient air, the oxygen of which providing a reference gas;
- and comprising
- movable granules (39) loosely retained and located in at least part of said hollow chamber (21) in which the layer-like reference electrode (22) is located, said granules being inert with respect to oxygen and having a surface hardness which is at least as great as that of the layer-like reference electrode (22).
Dependencies are inferred from the claim text.