Ngk Insulators, Inc.

Toyota Jidosha Kogyo Kabushiki Kaisha

Nippon Gaishi Kabushiki Kaisha

Shigeo Soejima

Syunzo Mase

Noboru Yamamoto

Masaaki Noguchi

Tadaaki Matsuhisa

Tetsuo Watanabe

Tsuchio Bunda

Shigetaka Wada

Tadashi Fujita

An electrochemical element comprising a laminar structure which includes a porous first layer of fully-stabilized zirconia ceramic, a second layer of partially-stabilized zirconia ceramic, and at least one pair of electrodes. At least one of the at least one pair of electrodes is disposed between the first and second layers, and in contact with the first layer.

Electrochemical element and method of making

An electrochemical device such as an oxygen sensor comprising: a plurality of solid electrolyte bodies; at least one pair of electrodes, each pair being disposed such that the electrodes are held in contact with the solid electrolyte bodies separately; at least one conductor sandwiched by two adjacent conductors of the solid electrolyte bodies; and at least one electrical insulation layer. A substantive portion of at least one side of the conductor indirectly contacts one of the two adjacent solid electrolyte bodies via the electrical insulation layer which is disposed therebetween, whereby the conductor is protected from direct contact with the associated solid electrolyte body. The insulation layer further serves to prevent noises which could otherwise be produced due to leakage current from the conductor. The conductor may be a lead connected to one of the electrodes, or to a heater for heating a portion of the solid electrolyte body adjacent the electrodes.

Electrochemical device

An electrochemical device such as an oxygen sensor comprising a plurality of solid electrolyte bodies, at least one pair of electrodes, each pair being disposed such that the electrodes are held in contact with the solid electrolyte bodies separately, at least one conductor sandwiched by two adjacent ones of the solid electrolyte bodies, and at least one electrical insulation layer. A substantive portion of at least one side of the conductor indirectly contacts with one of the two adjacent solid electrolyte bodies via the electrical insulation layer which is disposed therebetween, whereby the conductor is protected from direct contact with the associated solid electrolyte body. The insulation layer further serves to prevent noises which could otherwise be produced due to leakage current from the conductor. The conductor may be a lead connected to one of the electrodes, or a heater for heating a portion of the solid electrolyte body adjacent to the electrodes.

A method of manufacturing an electrochemical device having an electrochemical cell including a planar solid electrolyte body and at least two electrodes disposed in contact with the solid electrolyte body. The method comprising: forming a first unfired ceramic layer on one side of an unfired structure of the electrochemical cell, the first unfired ceramic layer being given a porous structure by firing thereof; forming a second unfired ceramic layer on the other side of the unfired structure of the electrochemical cell, the second unfired ceramic layer having substantially the same property of firing shrinkage as the first unfired ceramic layer; and co-firing the unfired structure of the electrochemical cell, the first and second unfired ceramic layers. The two unfired ceramic layers may be formed on opposite sides of an unfired structure of an electrochemical cell assembly which includes plural cells, for example, an oxygen pumping cell and an oxygen sensing cell. In this case, another unfired ceramic layer may be formed between the unfired structures of the two cells. The electrochemical device manufactured by the method does not have a unfavorable warpage that would arise due to difference in firing shrinkage between the layers.

Method of manufacturing an electrochemical device

An electrochemical element including a planar solid electrolyte body, and at least pair of electrodes including a first electrode and a second electrode which are disposed on the planar solid electrolyte body. The element has a thin flat space which has a predetermined diffusion resistance to a measurement gas and which communicates with an external space in which the measurement gas exists. The first electrode is disposed so that it is substantially exposed to the measurement gas in the thin flat space. The element includes a bridging member which is interposed between two opposed flat surfaces which partially define the thin flat space. The bridging member substantially determines the thickness of the thin flat space. The bridging member is formed by firing a mixture consisting of a filler material which disappears upon firing thereof, and ceramic grains which are fired into the bridging member. The mixture is applied in the form of a layer so as to occupy at least a portion of the thin flat space to be formed.

Electrochemical element

An electrochemical device for dealing with a measurement gas in an external measurement-gas space, including an electrochemical sensing element having a pumping cell and a sensing cell. The pumping cell has a first planar solid electrolyte body, and a first and a second electrode disposed on corresponding areas of opposite surfaces of the first solid electrolyte body. The sensing cell has a second planar solid electrolyte body, and a third and a fourth electrode disposed on the second solid electrolyte body. The sensing element has an internal measurement-gas space communicating with the external measurement-gas space, so that the measurement gas is introduced into the internal measurement-gas space with a predetermined diffusion resistance. The first and third electrodes are substantially exposed to the internal measurement-gas space. A reference gas is accommodated in a reference-gas space to which the second and fourth electrodes are substantially exposed to the reference-gas space. Thus, none of the electrodes are directly exposed to the external measurement-gas space.

An electrochemical device including a sensing element of laminar structure for determining the concentration of a component of a gas, comprising a first electrochemical cell including a first solid electrolyte body, and a first and a second porous electrode disposed on the first solid electrolyte body, a second electrochemical cell including a second solid electrolyte body, and a third and a fourth porous electrode disposed on the second solid electrolyte body, and a ceramic layer having a high electric resistance and sandwiched between the first and second electrochemical cells. In another aspect of the invention, the first solid electrolyte body is porous. In this case, the first and third electrodes are exposed to substantially the same atmosphere. In either case, the first and second, or third and fourth electrodes are disposed in alignment on opposite surfaces of the first or second solid electrolyte body. In the former case, the first and second cells serve as a pumping and sensing cell, respectively. In the latter case, the first and second cells serve as a sensing and a pumping cell, respectively.

Electrochemical sensing element and device incorporating the same

Zirconia powder is formed by dry grinding, and a slurry of the zirconia powder with a nonaqueous solvent is shaped and fired.

Method of producing ceramics

An electrochemical device of a laminar structure for determining the concentration of a component in a measurement gas, comprising: a pumping cell including a first and a second electrode disposed on a first planar solid electrolyte body; a sensing cell including a third and a fourth electrode disposed on a second planar solid electrolyte body; and a thin flat space to which the first and third electrodes are exposed and which communicates with an external space in which the measurement gas exists. The thin flat space has a diffusion resistance to the component in the measurement gas introduced through an inlet thereof. The first and third electrodes and the thin flat space are positioned and dimensioned relative to each other so that a distance 'l' is smaller than a distance 'm', as measured in a cross section perpendicular to planes of the solid electrolyte bodies, where the distance 'l' is measured between the inlet of the thin flat space and a point of the first electrode nearest to the inlet as measured in the above-indicated cross section, and the distance 'm' is measured between the inlet and a point of the third electrode nearest to the inlet as measured in the above-indicated cross section.

An electrochemical device comprising at least one electrochemical cell having a planar solid electrolyte body, and a first and a second electrode one of which is disposed on the solid electrolyte body. The device has a measurement-gas space communicating with an outside space for introducing a measurement gas, and a reference-gas space into which a reference gas is introduced. The first and second electrodes are exposed to the measurement-gas and reference-gas spaces, respectively. The measurement gas is introduced into the measurement-gas space with a diffusion resistance to molecules of a selected component of the measurement gas. The measurement-gas and reference-gas spaces are juxtaposed in spaced-apart relation with each other in substantially the same plane parallel to the planar solid electrolyte body. The device may include two electrochemical cells, on serving as a sensing cell having said first and second electrodes, and the other serving as a pumping cell haivng two electrodes one of which is exposed to the measurement-gas space. A heating layer may be disposed on the side of the sensing cell. In this case, the first and second electrodes are spaced from each other in the direction parallel to the solid electrolyte body.

An electrochemical element for detecting a component in a gaseous fluid in an external space, including a planar solid electrolyte body, and a first and a second electrode which are disposed in contact with the planar solid electrolyte body and cooperate with the planar solid electrolyte body to form an electrochemical cell. The electrochemical element has a thin flat space which communicates with the external space and which has a predetermined diffusion resistance to the molecules of the component. A thickness of the thin flat space as measured perpendicularly to a plane of the planar solid electrolyte body is larger at an inlet portion thereof at which the thin flat space communicates with the external space, than at a remote portion thereof remote from the inlet portion. The first electrode is located at the remote portion.

A measuring electrode is mounted on one side surface of a solid electrolyte, while a reference electrode is mounted on a separate solid electrolyte and disposed so as to face the opposite side surface of said one solid electrolyte across a gap.

Oxygen sensor element

An electrochemical device comprising at least one electrochemical cell having a planar solid electrolyte body, and a first and a second electrode one of which is disposed on the solid electrolyte body. The device has a measurement-gas space communicating with an outside space for introducing a measurement gas, and a reference-gas space into which a reference gas is introduced. The first and second electrodes are exposed to the measurement-gas and reference-gas spaces, respectively. The measurement gas is introduced into the measurement-gas space with a diffusion resistance to molecules of a selected component of the measurement gas. The measurement-gas and reference-gas spaces are juxtaposed in spaced-apart relation with each other in substantially the same plane parallel to the planar solid electrolyte body. The device may include two electrochemical cells, one serving as a sensing cell having said first and second electrodes, and the other serving as a pumping cell having two electrodes one of which is exposed to the measurement-gas space. A heating layer may be disposed on the side of the sensing cell. In this case, the first and second electrodes are spaced from each other in the direction parallel to the solid electrolyte body.

A process of manufacturing an electrochemical device including a pumping cell having a first and a second electrode, and a sensing cell having a third and fourth electrode such that the electrodes are disposed on at least one solid electrolyte body, and the second and fourth electrodes are exposed to the atmosphere in an internal cavity formed in the device. The process comprises a step of interposing an insert consisting essentially of a sublimable material in the cavity to be formed during superposition of green sheets or layers of the solid electrolyte bodies and electrodes into an unfired laminar structure, such that the insert is disposed opposite to the unfired layers of the second and fourth electrodes, and further comprises a step of co-firing the unfired laminar structure incorporating the insert so as to cause the insert to disappear through sublimation. The insert prevents portions of the solid electrolyte bodies from being extruded or displaced into the cavity while the stack of the green sheets of solid electrolyte is compressed into the unfired laminar structure.

Process of manufacturing electrochemical device

Zirconia powder is formed by dry grinding, and slurry of the zirconia powder with nonaqueous solvent is shaped and fired.

Growing community of inventors

Nagoya, Japan

Shigeo Soejima