JP2004338964A - Oxygen pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce occurrence of of local temperature distribution in an electrode film caused by heat dissipation through lead members. <P>SOLUTION: It is possible to suppress the local temperature lowering by applying a current via metallic members 6a, 6b arranged at outer peripheral parts 7 of the electrode films 3a, 3b without directly connecting the lead members 4a, 4b to the electrode films. Thereby, it becomes possible to provide an oxygen pump in which the occurrence of cracks in an oxygen ion conductive substrate 2 caused by thermal stress can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oxygen pump for electrochemically moving oxygen ions.
[0002]
[Prior art]
Conventionally, as this type of oxygen pump, an oxygen pump shown in FIG. 1 has been disclosed (for example, see Patent Document 1). The oxygen pump element 1 is configured by forming electrode films 3a and 3b on both sides of an oxygen ion conductive substrate 2. From the respective electrode films, lead members 4a and 4b are respectively extracted from specific portions and connected to a power supply (not shown).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-86204
[Problems to be solved by the invention]
However, in the conventional oxygen pump, heat during the operation of the oxygen pump is radiated from the lead members 4a and 4b, and a locally low temperature portion is generated in the oxygen ion conductive substrate 2, so that cracks occur due to thermal stress. There were challenges. Further, since the lead members 4a and 4b are directly connected to the electrode films 3a and 3b, the arrangement of the lead member take-out portion is uniquely determined, and the configuration of the oxygen pump element is limited. .
[0005]
[Means for Solving the Problems]
The present invention provides an oxygen pump element in which electrode films are formed on both surfaces of an oxygen ion conductive substrate, a metal member electrically connected to the outer periphery of the electrode film, and a metal member. It is an oxygen pump constituted by connected lead members.
[0006]
Since the lead member connects the metal member to the outer periphery instead of a part of the electrode film, it is possible to suppress a temperature unevenness due to a local temperature decrease due to heat radiation. Furthermore, if the lead member is connected to an arbitrary position on the metal member, the degree of freedom in taking out the power to the power source is increased.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 has a configuration in which a metal member electrically connected to the outer periphery of the electrode film and a lead member are attached to the metal member. Since the conductive metal member is electrically connected to the outer periphery of the electrode film, a uniform and gentle temperature decrease from the center to the outer periphery can be realized. Therefore, thermal stress due to temperature unevenness can be reduced, and cracking of the oxygen ion conductive substrate can be suppressed. Further, since the position of the lead member connected to the metal member can be arbitrarily changed, the degree of freedom of the configuration of the oxygen pump is increased.
[0008]
According to a second aspect of the present invention, an insulating material is disposed between two metal members. This can prevent the two metal members from coming into contact with each other and causing a short circuit.
[0009]
According to a third aspect of the present invention, the insulating material has at least one of a porous shape and a hollow shape. By adopting these shapes, heat insulation by air becomes possible, and heat loss can be reduced.
[0010]
In the invention described in claim 4, the insulating material is at least one of mica, alumina, and silica. Since these insulating materials have heat resistance at the operating temperature of the oxygen pump, thermal deterioration of the insulating materials can be suppressed.
[0011]
The invention described in claim 5 uses one of the metal members selected from nickel and an iron-chromium alloy. Since these metal members have a smaller Young's modulus than the oxygen ion conductive substrate, the thermal stress of the metal member generated due to the difference in thermal expansion coefficient between them is also small. Therefore, the adhesion between the oxygen ion conductive substrate and the metal member is maintained even at a high temperature.
[0012]
In the invention according to claim 6, the thickness of the metal member is 5 to 50 μm. Therefore, when strain occurs in a direction parallel to the surface of the metal member, the stress generated by the metal member can be reduced, and practical physical strength can be ensured.
[0013]
According to a seventh aspect of the present invention, the lead member is welded to the metal member. Therefore, the connection can be made easily and with high strength.
[0014]
In the invention according to claim 8, the lead member and the metal member are made of the same material. Therefore, the adhesive strength is improved and the reliability of the lead connection is increased.
[0015]
In a ninth aspect of the present invention, the material of the lead member and the metal member is nickel. Therefore, a highly reliable connection can be obtained at a low cost.
[0016]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
(Example 1)
FIG. 2 is an exploded perspective view illustrating a configuration of the oxygen pump according to the first embodiment of the present invention. FIG. 3 is a sectional view thereof.
[0018]
The oxygen pump element 1 is configured by forming the electrode films 3a and 3b on both surfaces of the oxygen ion conductive substrate 2. As the oxygen ion conductive substrate 2, zirconia doped with yttrium, ceria doped with samarium, or lanthanum gallate substituted with strontium or magnesium is used. Further, as the electrode films 3a and 3b, a baked film or a vapor-deposited film of a composite metal oxide made of platinum, silver, samarium strontium-cobalt or the like is used.
[0019]
The oxygen pump of the present invention is manufactured by forming the oxygen pump element 1 by screen printing and then bonding the metal members 6a and 6b to the outer peripheral portion 7 of the electrode film. At this time, the metal member 6a adjacent to the opening 8 is disposed so as to face the outer peripheral portion 7 of the electrode film 3a and the inner peripheral portion of the metal member 6b adjacent to the opening 8 and the outer periphery of the electrode film 3b. It is arranged so that it may face a part. Here, in order to avoid contact between the metal members 6a and 6b, an insulating material 9 may be inserted therebetween. As the insulating material 9, mica, alumina and silica can be used, but porous silica and glass wool are preferable.
[0020]
The metal members 6a and 6b are preferably nickel members or iron-chromium alloy members, but may be selected from titanium, gold and platinum. Further, the thickness of the metal member is desirably 5 to 50 μm. If the thickness is less than 5 μm, the physical strength is too small to be practical. On the other hand, if the thickness is more than 50 μm, the thermal stress increases and the film is easily peeled off, and the heat radiation also increases.
[0021]
As a method of connecting the lead members 4a, 4b to the metal members 6a, 6b, there are a brazing method, a welding method, a physical caulking method, and the like. I have. At the time of welding, it is most preferable that the lead member and the metal member are made of the same material. In particular, when the materials of the lead member and the metal member are nickel, which is inexpensive as a raw material, nickel foil having a thickness of 10 to 20 μm and a nickel member having a diameter of about 0.1 mm are inexpensively used because they are used industrially. It is.
[0022]
In the above configuration, when the oxygen ion conductive substrate is heated by a heater (not shown) and heated to 600 ° C. or higher, a DC voltage is applied using the electrode film 3b as a cathode electrode and the electrode film 3a as an anode electrode. Oxygen molecules in the cathode-side external space are taken into the oxygen ion conductive substrate 2 as oxygen ions from the cathode electrode film and reach the anode electrode. Oxygen ions that reach the anode electrode become oxygen molecules and diffuse into the external space on the anode side. Since the cathode-side external space and the anode-side external space are separated by at least one of the metal members 6a and 6b, oxygen can be moved from the anode-side external space to the cathode-side external space without returning. At this time, self-heating occurs in the oxygen ion conductive substrate 2, and the heat is transmitted to the outside through the lead portion. However, since the lead portions of the present embodiment are the metal members 6a and 6b provided on the outer periphery of the electrode films 3a and 3b, local heat transfer can be suppressed, and the uniform and gentle heat from the center to the outer periphery can be obtained. A temperature distribution can be realized. Therefore, cracking of the oxygen ion conductive substrate and the electrode film due to thermal stress can be prevented.
[0023]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to prevent the oxygen ion conductive substrate from cracking due to thermal stress.
[0024]
Further, according to the second to ninth aspects of the invention, the operation reliability of the oxygen pump can be secured, and the use durability can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a conventional oxygen pump. FIG. 2 is an exploded perspective view showing a configuration of an oxygen pump according to a first embodiment of the present invention. FIG. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Oxygen pump element 2 Oxygen ion conductive substrate 3a, 3b Electrode film 4a, 4b Lead member 6a, 6b Metal member 7 Outer peripheral part 9 Insulation material

Claims (9)

An oxygen pump comprising: an oxygen pump element having electrode films formed on both surfaces of an oxygen ion conductive substrate; a metal member electrically connected to an outer periphery of the electrode film; and a lead member connected to the metal member. The oxygen pump according to claim 1, wherein an insulating material is disposed between the two metal members. 3. The oxygen pump according to claim 2, wherein the shape of the insulating material is at least one of a porous shape and a hollow shape. 4. The oxygen pump according to claim 2, wherein the insulating material is at least one of mica, alumina, and silica. The oxygen pump according to claim 1, wherein the metal member is at least one of nickel and an iron-chromium alloy. The oxygen pump according to claim 5, wherein the thickness of the metal member is 5 to 50 m. The oxygen pump according to claim 1, wherein the lead member is welded to the metal member. The oxygen pump according to claim 7, wherein the lead member and the metal member have the same component. The oxygen pump according to claim 8, wherein the metal component is nickel.

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