JP2013232385A - Seal structure and fuel cell stack structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure that has excellent gas sealing properties, and to provide a fuel cell stack structure.SOLUTION: A seal structure is disposed between two separators that sandwich therebetween a unit cell in a fuel cell stack structure. The seal structure includes: a flow passage member that is disposed on a first separator side; a flow passage member that is disposed on a second separator side; and a seal member that is disposed between the two flow passage members. In the seal structure, at least one of the flow passage members is a welded member that is welded with a weld bead formed in at least one recess formed in at least one of two or more members. A fuel cell stack structure includes the seal structure.

Description

  The present invention relates to a seal structure and a fuel cell stack structure. More specifically, the present invention relates to a seal structure and a fuel cell stack structure that can exhibit excellent gas sealing properties.

  Conventionally, a stack structure of a solid oxide fuel cell has been proposed, which can increase the degree of freedom of the joining method and joining process and improve the yield of the joining process, and can eliminate almost no concern about gas leakage. (See Patent Document 1).

  This stack structure has a single cell, one metal separator having a circular thin plate shape and having a gas introduction port and a discharge port in the central portion and a cell mounting portion for fixing the single cell, and a circular thin plate shape. The other metal separator having a gas inlet and outlet at the center and a space formed between the two separators and communicating with the gas inlet and outlet of both separators. A flow path component for supplying and discharging gas is provided. The stack structure is formed by laminating a solid oxide fuel cell in which the flow path component is joined to at least one of the separators on the inner side of the space. Further, in this stack structure, solid oxide fuel cells that overlap each other are fixed by welding of stepped portions located at the central portion of each separator.

JP 2006-147532 A

  However, as a result of studies by the present inventors, it has been found that the stack structure described in Patent Document 1 is deformed due to protrusion of the weld bead and heat input during welding. And in ensuring more strict gas-sealing performance, the flatness is not sufficiently ensured, and there is room for improvement in gas-sealing performance.

  The present invention has been made in view of such problems of the prior art. And the place made into the objective is to provide the sealing structure and fuel cell stack structure which can exhibit the outstanding gas-sealing property.

  The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, a flow path member disposed on one separator side, a flow path member disposed on the other separator side, and a seal member disposed between the two flow path members, By configuring at least one of the flow path members as a welded joint member welded with a weld bead formed in at least one recess formed in at least one of the two or more members, the above object is achieved. The inventors have found that this can be achieved and have completed the present invention.

That is, the seal structure of the present invention is a seal structure disposed between two separators sandwiching a single cell in a fuel cell stack structure.
The seal structure of the present invention includes a flow path member disposed on one separator side, a flow path member disposed on the other separator side, and a seal disposed between the two flow path members. A member.
In the seal structure of the present invention, at least one of the flow path members is a welded joint member welded with a weld bead formed in at least one recess formed in at least one of the two or more members. is there.

  The fuel cell stack structure of the present invention includes the above-described seal structure of the present invention.

According to the present invention, the flow path member disposed on one separator side, the flow path member disposed on the other separator side, and the seal member disposed between the two flow path members. And at least one of the flow path members is a weld joint member welded with a weld bead formed in at least one recess formed in at least one of the two or more members.
Therefore, it is possible to provide a seal structure and a fuel cell stack structure that can exhibit excellent gas sealing properties. Such a fuel cell stack structure can improve fuel utilization by exhibiting excellent gas sealing properties.

1 is a schematic perspective view showing an example of a fuel cell stack structure according to a first embodiment of the present invention. It is a fragmentary sectional view in the fuel cell stack structure concerning a 1st embodiment. It is the elements on larger scale which show an example of the field surrounded by the A line of the fuel cell stack structure concerning a 1st embodiment. It is a graph which shows the curvature amount of the flow-path member when not forming when the groove | channel is formed. It is a graph which shows the shrinkage | contraction amount of the flow-path member when not forming when the groove | channel is formed. It is a graph which shows the gas leak amount in the two-stage stack when not forming with the groove formed. It is the elements on larger scale which show another example of the area | region enclosed by the A line of the fuel cell stack structure which concerns on 1st Embodiment. It is the elements on larger scale which show another example of the area | region enclosed by the A line of the fuel cell stack structure which concerns on 1st Embodiment. It is a fragmentary sectional view in the fuel cell stack structure concerning a 2nd embodiment. It is the elements on larger scale which show an example of the area | region enclosed by the B line of the fuel cell stack structure which concerns on 2nd Embodiment. It is a fragmentary sectional view in the fuel cell stack structure concerning a 3rd embodiment. It is the elements on larger scale which show an example of the area | region enclosed by the C line of the fuel cell stack structure which concerns on 3rd Embodiment. It is a fragmentary sectional view in the fuel cell stack structure concerning a 4th embodiment. It is the elements on larger scale which show an example of the area | region enclosed by the D line of the fuel cell stack structure which concerns on 4th Embodiment. It is the elements on larger scale which show another example of the area | region enclosed by D line of the fuel cell stack structure which concerns on 4th Embodiment. It is explanatory drawing of the cross-sectional shape of the groove | channel in the fuel cell stack structure which concerns on 5th Embodiment.

  Hereinafter, a seal structure and a fuel cell stack structure according to an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where the structure is applied to a solid oxide fuel cell stack structure. In addition, the dimension ratio of drawing quoted by the following embodiment is exaggerated on account of description, and may differ from an actual ratio.

(First embodiment)
FIG. 1 is a schematic perspective view showing an example of a fuel cell stack structure according to the first embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the fuel cell stack structure according to the first embodiment. FIG. 4 is a partially enlarged view showing an example of a region surrounded by line A in FIG. 3.

  A fuel cell stack structure (hereinafter referred to as “cell stack”) 1 of the present embodiment is formed by laminating a plurality of solid oxide fuel cells (hereinafter referred to as “cell units”) 10 with a predetermined gap therebetween. So that power generation is performed by separating and circulating two kinds of reaction gases from each other through a holder portion in which a gas inlet and a gas outlet are arranged inside and outside the cell unit 10. It is a thing.

  In the present embodiment, one reaction gas is a hydrocarbon fuel (fuel gas) and the other reaction gas is air, but the relative arrangement of the air electrode and fuel electrode of the cell unit, which will be described in detail later. Accordingly, one reaction gas may be air and the other reaction gas may be a hydrocarbon fuel.

  The cell unit 10 is mainly composed of a solid oxide single cell 11, a thin channel member 12, a channel forming body 13 and a separator 14.

  The single cell 11 has the above-described fuel electrode (anode electrode) 11A and air electrode (cathode electrode) 11C opposite to each other on the upper and lower sides of the electrolyte 11B. Is formed.

The separator 14 is a metal plate having an outer diameter larger than the outer diameter of the unit cell 11. A circular hole 14 a is formed at the center of the separator 14, and the inner peripheral surface (lower surface) of the outer peripheral edge of the intermediate portion thereof. In addition, a metal porous body 14A for current collection that is in contact with the fuel electrode 11A of the single cell 11 is disposed.
Although not shown in the figure, an annular spacer is fixed to the outer peripheral edge of the separator 14, and an annular inner peripheral plate extends inwardly on the upper surface of the spacer. It is fixed in the state. Further, the lower surface of the spacer and the upper surface of the outer peripheral edge of the electrolyte are bonded and fixed with a glass adhesive interposed therebetween.

  The flow path forming body 13 includes flow path members 13A and 13B, which are connected in common with a flow path for supplying and discharging any of the reaction gases to the gas circulation space β. Let it form.

The flow path member 13 </ b> A has a cylindrical shape having an outer diameter slightly smaller than the inner diameter of the through hole 11 a of the single cell 11.
The flow path member 13B has a gas circulation groove 13c formed on the lower surface thereof so that the flow path 13b and the gas flow space β communicate with each other, and has a slightly larger outer diameter than the thin flow path member 12 described later. It is formed in a plate shape.

The thin channel member 12 is a metal plate that has an annular shape with an outer diameter larger than that of the through hole 11 a of the single cell 11.
That is, by forming an annular shape having an outer diameter larger than the through-hole 11a of the single cell 11, it is overlapped with the inner peripheral edge of the single cell 11 in plan view, and the glass adhesive 15 is interposed in this overlapped portion. The single cell 10 is bonded to the upper surface of the inner peripheral edge.
The flow path forming body 13, the thin flow path member 12, and the separator 14 are all arranged concentrically with the axis O as the center.

  In addition, in a state where it is adhered to the upper surface of the inner peripheral edge of the single cell 11 through the glass adhesive 15, the flow path is formed so as to generate a gap between the lower surface of the fuel electrode 11A of the single cell 11 and the flow path member 13B. The height of the member 13A is set.

The flow path forming body 13 having the above-described configuration is formed separately from this, and a seal structure 20 for securing a seal is integrally fixed thereto.
This seal structure 20 is for ensuring a seal between other adjacent cell units 10.

  The seal structure 20 has a single cell so that the single cell 11 is not deformed or damaged by the action of the force of pressing (squeezing) the stacked cell units 10 from above and below. 11 is formed in a circular shape in plan view with a diameter that holds the inner peripheral edge region, and with a required thickness. Further, the seal structure 20 is formed with a through hole 20 a penetratingly communicating with the flow path of the flow path forming body 13.

  That is, by securing the above-described seal, it is possible to improve the adhesion with other cell units 10 that are adjacently stacked, and to maintain good sealing performance regardless of the environmental temperature. The load can be reduced.

  In the present embodiment, the seal structure 20 is integrally fixed to the upper surface (outer surface) of the thin flow path member 12 and is also fixed to the lower surface (outer surface) of the separator 14 integrally.

The seal structure 20 will be specifically described with reference to FIG. The seal structure 20 includes a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side, and a sheet shape disposed between the two flow path members. The sealing member 23 is provided. And one flow path member 22 is welded by the weld bead 24 formed in the recessed part 22a formed in the position which opposes the sealing member of member 22A among two members 22A and 22B, and turns into a welding joining member. .
Thus, by forming the weld bead in the groove-shaped recess, the weld bead does not protrude and the sealing surface can be flattened, so that the gas sealability can be improved.
In addition, the groove-shaped recessed part may be formed continuously in a circle or may be formed discontinuously. In welding, for example, laser welding is preferably applied, but the present invention is not limited to this.
In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

  FIG. 4 is a graph showing the warpage amount of the flow path member when the groove is formed and not formed, and FIG. 5 is the contraction amount of the flow path member when the groove is formed and not formed. FIG. 6 is a graph showing the amount of gas leak in the two-stage stack when the groove is formed and when the groove is not formed. If no groove was formed, a voltage of 9 V was required to heat and weld to a depth of 0.95 mm. If a groove was formed, heat was applied to a depth of 0.7 mm and welding was performed. It took 6v to do this. In the test for determining the amount of gas leak, an acceleration test was performed in which helium was supplied at a pressure of 10 kPa at room temperature (20 ° C.).

  From FIG. 4, it can be seen that the amount of warpage is 25.7 μm to 18.2 μm, which can be reduced by 29%. Further, it can be seen from FIG. 5 that the contraction amount is changed from 36.7 μm to 25.7 μm, which can be reduced by 30%. Furthermore, it can be seen that the required voltage can be reduced by 26%. This also shows that the advantage that manufacturing cost can be reduced is obtained. Furthermore, it can be seen from FIG. 6 that the gas leak amount is reduced from 2.5 cc / min to 0.2 cc / min, which can be reduced by 92%.

FIG. 7 is a partially enlarged view showing another example of the region surrounded by the A line of the fuel cell stack structure according to the first embodiment. Note that the fuel cell stack structure of this example has the same configuration as that of the above example except for the region surrounded by the A line, and the description thereof will be omitted.
The seal structure 20 in this example is disposed between two flow path members, a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side. The sealing member 23 is provided. And one flow path member 22 is welded with a weld bead 24 formed in one of the plurality of recesses 22a formed in the member 22A of the two members 22A and 22B, and becomes a welded joint member. .
Thus, even if the weld bead is formed in at least one of the plurality of groove-shaped recesses, the weld bead does not protrude and the sealing surface can be flattened, so that the gas sealing property is improved. Can do. Moreover, since the pressure decreases when the leaked gas passes through the plurality of grooves, the gas sealing performance is further improved. Furthermore, since the concave portion is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

FIG. 8 is a partially enlarged view showing still another example of the region surrounded by the A line of the fuel cell stack structure according to the first embodiment. Note that the fuel cell stack structure of this example has the same configuration as that of the above example except for the region surrounded by the A line, and the description thereof will be omitted.
The seal structure 20 in this example is disposed between two flow path members, a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side. The sealing member 23 is provided. And one flow path member 22 is welded by the weld bead 24 formed in all of the some recessed part 22a formed in member 22A among two members 22A and 22B, and turns into a welding joining member.
Thus, even if the weld bead is formed in all of the plurality of groove-shaped recesses, the weld bead does not protrude and the sealing surface can be flattened, so that the gas sealing property can be improved. . In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

(Second Embodiment)
FIG. 9 is a partial cross-sectional view of the fuel cell stack structure according to the second embodiment, and FIG. 10 is a portion showing an example of a region surrounded by line B of the fuel cell stack structure according to the second embodiment. It is an enlarged view. In addition, about the thing equivalent to what was demonstrated in 1st Embodiment, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

The seal structure 20 ′ in this example is provided between a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side, and the two flow path members. The sealing member 23 is provided. And one flow path member 21 is welded by the weld bead 24 formed in the recessed part 21a formed in member 21A among two members 21A and 21B, and turns into a welding joining member. At this time, a recess 22a is also formed at a position facing the weld bead of the other flow path member 22 so that the seal member 23 disposed on the side from which the weld bead 24 protrudes is not damaged.
Thus, by forming the weld bead in the groove-shaped recess, the weld bead does not protrude and the sealing surface can be flattened, so that the gas sealability can be improved. Moreover, even when the concave portion where the weld bead is formed and the seal member do not face each other, by forming the concave portion on the side from which the weld bead protrudes, the flatness as the seal structure can be secured, Gas sealability can be improved. In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

(Third embodiment)
FIG. 11 is a partial cross-sectional view of the fuel cell stack structure according to the third embodiment, and FIG. 12 is a portion showing an example of a region surrounded by the C line of the fuel cell stack structure according to the third embodiment. It is an enlarged view. In addition, about the thing equivalent to what was demonstrated in 1st or 2nd embodiment, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

The seal structure 20 ″ in this example is provided between a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side, and the two flow path members. The two flow path members 21 and 22 are formed in the recesses 21b and 22a formed in the members 21B and 22A out of the two members 21A and 21B and 22A and 22B, respectively. The weld bead 24 is welded to form a weld joint member.
Thus, by forming the weld bead in the groove-shaped recess, the weld bead does not protrude and the sealing surface can be flattened, so that the gas sealability can be improved. In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

(Fourth embodiment)
FIG. 13 is a partial cross-sectional view of the fuel cell stack structure according to the fourth embodiment, and FIG. 14 is a portion showing an example of a region surrounded by the D line of the fuel cell stack structure according to the fourth embodiment. It is an enlarged view. In addition, about the thing equivalent to what was demonstrated in 1st-3rd embodiment, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

The seal structure 20 ″ ′ in this example includes a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side, and the two flow path members. And a ring-shaped seal member 23 disposed in the recess. And one flow path member 22 is welded by the weld bead 24 formed in the recessed part 22a formed in member 22A among two members 22A and 22B, and turns into a welding joining member.
As described above, by disposing the weld bead and the ring-shaped seal member in the groove-shaped recess so that they do not interfere with each other, the weld bead does not protrude and the gas sealability can be improved. . In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

FIG. 15 is a partially enlarged view showing another example of the region surrounded by the D line of the fuel cell stack structure according to the fourth embodiment. Note that the fuel cell stack structure of this example has the same configuration as that of the above example except for the region surrounded by the D line, and thus the description thereof is omitted.
The seal structure 20 ″ ′ in this example includes a flow path member 21 disposed on one separator side, a flow path member 22 disposed on the other separator side, and the two flow path members. And a ring-shaped seal member 23 disposed in the recess. And one flow path member 22 is welded by the weld bead 24 formed in the recessed part 22a formed in member 22A among two members 22A and 22B, and turns into a welding joining member. At this time, the other flow path member 21 facing the one flow path member 22A formed with the concave portion via the seal member 23 has the convex portion 21c at a position facing the concave portion 22a, and the concave portion 22a and the convex portion 21c is fitted.
As described above, by disposing the weld bead and the ring-shaped seal member in the groove-shaped recess so that they do not interfere with each other, the weld bead does not protrude and the gas sealability can be improved. . At this time, the gas sealing property can be further improved by the concave portion and the convex portion provided to face each other. In addition, since the recess is welded during welding, the amount of heat input during welding is reduced, and warping (shrinkage) during welding is suppressed. This also ensures the flatness of the sealing surface and improves the gas sealing performance.

(Fifth embodiment)
FIG. 16 is an explanatory diagram of the cross-sectional shape of the groove in the fuel cell stack structure according to the fifth embodiment. In addition, about the thing equivalent to what was demonstrated in the 1st-4th embodiment, the code | symbol same as them is attached | subjected and description is abbreviate | omitted.

  In the present embodiment, the shape in the cross section perpendicular to the longitudinal direction of the groove is preferably rectangular (see (A)) or semicircular (see (B)). However, it is not limited to these. Rectangular or semicircular grooves can be formed by machining. In addition, there is an advantage that the semicircular groove can be easily formed by half etching. From the viewpoint of workability, the groove having a rectangular cross-sectional shape preferably has a narrow width, and is currently about 0.4 mm, and is suitable for a thick plate member. If the weld bead does not protrude, the minimum radius can be 0.1 mm at the present time, which is suitable for a thin plate member.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  For example, the configuration described in each embodiment described above is not limited to each embodiment. For example, the details of the configuration such as the position, the number, and the shape of the recesses are changed, or the configuration of each embodiment is described above. It is possible to make combinations other than the embodiments described above.

  In addition, for example, a seal structure disposed between two separators sandwiching a single cell in a fuel cell stack structure has been described. In a polymer electrolyte fuel cell, a welded portion of a separator assembly, a seal member, The sealing structure of the present invention can also be applied when performing gas sealing by contacting the above. Specifically, a concave portion is formed on one side of the separator joined body so that a weld bead is formed inside thereof, or a concave portion is formed on both sides of the separator joined body, and a weld bead is formed inside them. And so on.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack structure, 10 ... Solid oxide fuel cell, 11 ... Single cell, 11A ... Fuel electrode, 11B ... Electrolyte, 11C air electrode, 12 ... Thin channel member, 13 ... Channel formation body, 13A , 13B ... flow path member, 14 ... separator, 14A ... metal porous body, 15 ... glass adhesive, 20, 20 ', 20 ", 20'" ... seal structure, 21, 22 ... flow path member, 21A , 21B, 22A, 22B ... member, 23 ... seal member, 21a, 21b, 22a ... concave portion, 21c ... convex portion, 24 ... weld bead

Claims (8)

A seal structure disposed between two separators sandwiching a single cell in a fuel cell stack structure,
A flow path member disposed on one separator side, a flow path member disposed on the other separator side, and a seal member disposed between the two flow path members,
At least one of the flow path members is a welded joint member welded with a weld bead formed in at least one recess formed in at least one of two or more members.   The seal structure according to claim 1, wherein the recess is a groove.   The seal structure according to claim 1 or 2, wherein the seal member is a sheet-like seal member disposed between the two flow path members.   The seal structure according to claim 3, wherein the recess is formed at a position facing the sheet-like seal member.   The seal structure according to claim 1 or 2, wherein the seal member is a ring-shaped seal member disposed between the two flow path members and disposed in the recess.   One flow path member formed with the concave portion and the other flow path member opposed via the seal member have a convex portion at a position facing the concave portion, and the concave portion and the convex portion are fitted to each other. The seal structure according to claim 1, wherein the seal structure is formed.   The seal structure according to claim 2, wherein a shape in a cross section perpendicular to the longitudinal direction of the groove is rectangular or semicircular.   A fuel cell stack structure comprising the seal structure according to any one of claims 1 to 7.

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