Gas composition sensor and method for separately detecting components of exhaust gas to diagnose catalytic converter performance
First Claim
1. A gas composition sensor for detecting oxygen, hydrocarbon-group fuel, or a combusted composition, comprising a pair of sensing elements, each having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other, and a gas diffusion limiting member coating said detecting electrode,a heater for setting, in substantially the same time phase, both of said sensing elements to operating temperatures different from each other for said sensing elements to have sensitivity coefficients to specified gas components different from each other, said sensing elements being operatively arranged and operable to selectively detect a specified gas component by way of said sensing elements having the different sensitivity coefficients.
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Abstract
A gas composition sensor for detecting oxygen, and hydrocarbon group fuel or combustible composition produced after combustion having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other and a sensing element composed of a gas diffusion limiting member coating the detecting electrode, which further comprises a pair of the sensing elements and heaters for setting both of the sensing elements to operating temperatures different from each other, whereby a specified gas component is selectively detected by operating both of the sensing elements so as to have sensitivity coefficients to the specified gas component different from each other.
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Citations
16 Claims
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1. A gas composition sensor for detecting oxygen, hydrocarbon-group fuel, or a combusted composition, comprising a pair of sensing elements, each having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other, and a gas diffusion limiting member coating said detecting electrode,
a heater for setting, in substantially the same time phase, both of said sensing elements to operating temperatures different from each other for said sensing elements to have sensitivity coefficients to specified gas components different from each other, said sensing elements being operatively arranged and operable to selectively detect a specified gas component by way of said sensing elements having the different sensitivity coefficients.
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10. A gas composition sensor for detecting at least one of oxygen and any one of hydrocarbon-group fuel and a combusted composition, comprising a pair of sensing elements, each having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other, and a gas diffusion limiting member coating said detecting electrode, wherein
said detecting electrode is arranged so as to be exposed to the at least one of oxygen and any one of the hydrocarbon-group fuel and the combusted composition to be detected, and said reference electrode is exposed to any one of atmospheric air and an atmosphere containing oxygen, and said gas composition sensor further comprises a heater for heating said pair of sensing elements, said heater being coated with a ceramic layer to be heat-insulated and arranged so as to heat said pair of sensing elements to different temperatures in substantially the same time phase.
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11. A gas composition sensor for detecting at least one of oxygen and any one of hydrocarbon-group fuel and combusted composition, comprising a pair of sensing elements, each having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other, and a gas diffusion limiting member coating said detecting electrode, wherein
said detecting electrode is arranged so as to be exposed to the at least one of oxygen and any one of the hydrocarbon-group fuel and the combusted composition to be detected, and said reference electrode is exposed to any one of atmospheric air and an atmosphere containing oxygen, and said gas composition sensor further comprises a heater for heating said pair of sensing elements to temperatures different from each other in substantially the same time phase, an insulating ceramic layer being provided between said heater and said sensing elements to moderate strain due to thermal expansion difference, a ceramic heat insulating coating layer being selectively provided in said heater in a portion opposite to said sensing elements.
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12. A gas composition sensor for detecting oxygen and any one of hydrocarbon group fuel and combustible composition produced after combustion, comprising a pair of cylindrically shaped sensing elements, each having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other, and a gas diffusion limiting member coating said detecting electrode, wherein
said reference electrode is arranged over an entire inside surface of said solid electrolyte body and an outside surface of said detecting electrodes in the pair of said sensing elements is coated with a porous ceramic layer comprising said gas diffusion limiting member.
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14. A gas composition sensor for detecting at least one of oxygen and any one of hydrocarbon-group fuel and combusted composition, comprising:
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a zirconia solid electrolyte body; a pair of sensing elements, one of which sensing elements is a first concentration cell having a first platinoid metal catalytic detecting electrode and a reference electrode, arranged opposite each other to sandwich said zirconia solid electrolyte therebetween, and a second concentration cell having a second platinoid metal catalytic detecting electrode and said reference electrode opposite each other to sandwich said zirconia solid electrolyte therebetween; a gas diffusion limiting member in the form of a coating on said detecting electrodes; a heater for heating said pair of sensing elements; wherein said pair of sensing elements have a positional relationship with said heater to be heated in substantially the same time phase to different operating temperatures specific to gas components so as to have sensitivity coefficients specific to respective specific gas components. - View Dependent Claims (15, 16)
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Specification