Air/fuel ratio sensor
First Claim
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1. An air/fuel ratio sensor, comprising:
- an air/fuel ratio detector comprised of a laminated body formed by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode, and a porous protection film on one another; and
a ceramic substrate having a heater built therein, wherein said air/fuel ratio detector and said ceramic substrate are joined to each other in layered form, wherein part of said oxygen reference electrode is shaped in a pattern having a form extremely thinner than the remaining portion thereof, and said pattern of thinner form is directly in contact with an exhaust gas atmosphere through layer-to-layer spacing of said laminated body which constitutes said air/fuel ratio detector, and wherein said oxygen reference electrode, said negative electrode and said positive electrode in said laminated body constituting said air/fuel ratio detector are provided so as to be shorter in length than said dense solid electrolyte, said porous solid electrolyte and said protection film and biased to a longitudinally-extending one end of said laminated body, whereby said air/fuel ratio detector is positioned at a longitudinally-extending one end of a laminated structure, and a pattern for said heater is shaped in the form of such a pattern that said air/fuel ratio detector side is dense and gradually becomes less dense towards an end on the opposite side of said air/fuel ratio detector as viewed in the longitudinal direction of said laminated body.
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Abstract
A detector for an air/fuel ratio sensor, which is comprised of a structure formed by stacking an oxygen reference electrode, a dense zirconia solid electrolyte, a negative electrode, a porous zirconia solid electrolyte, a positive electrode and a porous protection film on one another, is formed over a ceramic substrate having a heater built therein. Thus, a combined air/fuel ratio sensor can be obtained which is operated in a short time (about 5 seconds or less) after power-on so as to comply with emission control applied immediately after startup and provides low power consumption and a high degree of reliability.
32 Citations
12 Claims
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1. An air/fuel ratio sensor, comprising:
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an air/fuel ratio detector comprised of a laminated body formed by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode, and a porous protection film on one another; and
a ceramic substrate having a heater built therein, wherein said air/fuel ratio detector and said ceramic substrate are joined to each other in layered form, wherein part of said oxygen reference electrode is shaped in a pattern having a form extremely thinner than the remaining portion thereof, and said pattern of thinner form is directly in contact with an exhaust gas atmosphere through layer-to-layer spacing of said laminated body which constitutes said air/fuel ratio detector, and wherein said oxygen reference electrode, said negative electrode and said positive electrode in said laminated body constituting said air/fuel ratio detector are provided so as to be shorter in length than said dense solid electrolyte, said porous solid electrolyte and said protection film and biased to a longitudinally-extending one end of said laminated body, whereby said air/fuel ratio detector is positioned at a longitudinally-extending one end of a laminated structure, and a pattern for said heater is shaped in the form of such a pattern that said air/fuel ratio detector side is dense and gradually becomes less dense towards an end on the opposite side of said air/fuel ratio detector as viewed in the longitudinal direction of said laminated body. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A combined air/fuel ratio sensor, comprising:
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an air/fuel ratio detector formed by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode and a porous protection film on one another;
an NOx detector formed by stacking a porous oxide, an NOx detecting electrode and a dense solid electrolyte on one another; and
a ceramic substrate having a heater built therein; and
wherein said air/fuel ratio detector, said NOx detector and said ceramic substrate are integrally joined to one another so as to be constructed as a single laminated structure.
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9. A combined air/fuel ratio sensor, comprising:
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an air/fuel ratio detector formed by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode and a porous protection film on one another;
an HC detector formed by stacking a porous oxide, an HC detecting electrode and a dense solid electrolyte on one another; and
a ceramic substrate having a heater built therein; and
wherein said air/fuel ratio detector, said HC detector and said ceramic substrate are integrally joined to one another so as to be constructed as a single laminated structure.
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10. A combined air/fuel ratio sensor, comprising:
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an air/fuel ratio detector obtained by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode and a porous protection film on one another, said air/fuel ratio detector being formed over one surface of a ceramic substrate having a heater built therein; and
an NOx detector obtained by stacking an oxygen reference electrode, a dense solid electrolyte, an NOx detecting electrode and a porous oxide on one another, said NOx detector being formed over the other surface of said ceramic substrate; and
wherein the oxygen reference electrode of said air/fuel ratio detector and the oxygen reference electrode of said NOx detector are in communication with each other via a through hole defined in said ceramic substrate.
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11. A combined air/fuel ratio sensor, comprising:
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an air/fuel ratio detector obtained by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode and a porous protection film on one another, said air/fuel ratio detector being formed over one surface of a ceramic substrate having a heater built therein; and
an HC detector obtained by stacking an oxygen reference electrode, a dense solid electrolyte, an HC detecting electrode and a porous oxide on one another, said HC detector being formed over the other surface of said ceramic substrate; and
wherein the oxygen reference electrode of said air/fuel ratio detector and the oxygen reference electrode of said HC detector are in communication with each other via a through hole defined in said ceramic substrate.
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12. A combined air/fuel ratio sensor, comprising:
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an air/fuel ratio detector formed of a laminated body obtained by stacking an oxygen reference electrode, a dense solid electrolyte, a negative electrode, a porous solid electrolyte, a positive electrode and a porous protection film on one another;
a ceramic substrate having a heater built therein, which is joined to said air/fuel ratio detector in layered form; and
an NOx detector constructed by cutting out part of said porous solid electrolyte, placing a dense solid electrolyte and surrounding insulating materials in a cut-out portion formed by cutting out the part of said porous solid electrolyte, and forming an electrode over the upper surface of the placed dense solid electrolyte.
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Specification