JP2018055897A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in that since a sealing material is continuous with a fixed width in a conventional fuel cell, damage such as crack may occur due to cumulative stress when the sealing material contracts as a result of burning.SOLUTION: A fuel cell comprises: a cell structure 3 having a structure in which an electrolyte 5 is sandwiched between an anode electrode 6 and a cathode electrode 7; a pair of separators 4 arranged on both sides of the cell structure 3; and a sealing member S air-tightly joining the cell structure 3 and at least the peripheral edge part of each separator 4. The sealing member S comprises: a main-line part Sa continuous along the peripheral edge part and having the same cross-sectional shape in the continuous direction; and an increase part Sb that partially increases the volume of the main-line part Sa. In the fuel cell FC, increase parts Sb are arranged at predetermined intervals with respect to the main-line part Sa. Stress on the entire main-line part Sa is prevented, a sealing material is refilled in the main-line part Sa from an increase part Sb, and damage to the sealing member S during manufacture is prevented.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an improvement in a fuel cell having a structure in which a cell structure is sandwiched between a pair of separators and a seal member is disposed between the cell structure and the separator.

  As a conventional fuel cell, there is one described in Patent Document 1, for example. The fuel cell described in Patent Document 1 includes a frame having a support surface, an electrolyte sheet, and a seal material inserted between the frame and the electrolyte sheet, and the seal material has a serpentine surface shape. . The sealing material is made of, for example, a glass material, and is fired after application. This fuel cell is intended to minimize or eliminate the possibility of any crack formation in the high stress region of the electrolyte sheet by applying a serpentine pattern to the sealing material.

Special table 2010-536145 gazette

  However, in the conventional fuel cell as described above, since the sealing material is continuous with a substantially constant cross-sectional area, when the sealing material shrinks due to firing during manufacturing, cumulative stress is generated in the continuous direction. However, there is a problem that there is no possibility of damage such as cracks in the sealing material, and it has been a problem to solve such a problem.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a fuel cell capable of preventing damage to a seal member during manufacturing.

  The fuel cell according to the present invention includes a cell structure having a structure in which an electrolyte is sandwiched between an anode electrode and a cathode electrode, a pair of separators disposed on both sides of the cell structure, and at least one of the cell structure and each separator. And a sealing member that hermetically joins between the peripheral portions. In the fuel cell, the sealing member includes a main line portion that is continuous along the peripheral edge portion and has the same cross-sectional shape in the continuous direction, and an increasing portion that partially increases the volume of the main line portion, and The increase portion is arranged at a predetermined interval with respect to the main line portion.

  The fuel cell according to the present invention has a configuration in which the sealing member is not a constant cross-sectional area in the continuous direction, but is provided with an increasing portion that partially increases the volume of the main line portion at a predetermined interval. The increased portion is divided into a plurality of short lines. For this reason, in the fuel cell, even if the seal member contracts by firing at the time of manufacture, no stress is exerted on the entire main line portion, that is, no cumulative stress is generated, and the main portion is replenished with the sealing material from the increased portion. Thereby, the fuel cell can prevent the seal member from being damaged during manufacture.

It is a disassembled perspective view of the fuel cell stack explaining 1st Embodiment of this invention. It is sectional drawing of the long side part of a fuel cell. It is a top view with an enlarged view explaining the sealing member of a fuel cell. It is a top view with an enlarged view explaining 2nd Embodiment of the fuel cell of this invention. It is a top view with an enlarged view explaining 3rd Embodiment of the fuel cell of this invention. It is a top view (A) which shows the 4th and 5th embodiment, respectively (B). It is each sectional drawing (A)-(G) explaining the various shapes of a sealing member as 6th Embodiment. It is a graph which shows the relationship between the compression amount by the cross-sectional shape of a sealing member, and a load. It is sectional drawing (A) which shows 7th Embodiment of a sealing member and a separator, and sectional drawing (B) which shows 8th Embodiment of a sealing member.

<First Embodiment>
FIG. 1 is a diagram schematically showing a fuel cell stack FS including a fuel cell FC according to the present invention. The illustrated fuel cell stack FS has a structure in which cell structures 3 having frames 2 around a power generation region 1 and separators 4 are alternately stacked. Although two cell structures 3 are shown in FIG. 1, a large number of cell structures 3 are actually stacked. Further, in the fuel cell stack FS, the number of separators 4 is one more than the number of cell structures 3 for the purpose of forming gas flow regions on both surfaces of each cell structure 3.

  In the fuel cell FC, the cell structure 3 includes a frame 2 that holds the periphery thereof, and includes the cell structure 3 and a pair of separators 4 and 4. That is, in the fuel cell stack FS shown in FIG. 1, adjacent fuel cells FC share the separator 4 between them to form the respective fuel cells FC.

  The cell structure 3 is a plate-like multi-layer structure having a planar rectangle. As shown in FIG. 2, a part of the cell structure 3 is an upper cathode electrode (air electrode) 6 in the figure and a lower anode in the figure. It has a structure in which an electrolyte 5 is sandwiched between an electrode (fuel electrode) 7. The cell structure 3 has a support plate 8 made of a porous material such as foam metal on the anode electrode 7 side. This cell structure 3 has a mechanical strength increased by the support plate 8 while maintaining gas permeability to the anode electrode 7, and may be referred to as a metal support cell, for example.

  The frame 2 is a part of the cell structure 3 and the material thereof is not particularly limited, but resin or metal can be used. The frame 2 may be integrally formed with the power generation region 1 including the electrolyte 5, the cathode electrode 6, and the anode electrode 7. Further, the frame 2 uses a porous support plate 8 having a size capable of disposing the power generation region 1 in the center, and the periphery of the support plate 8 is compressed and densified. Part).

  The cell structure 3 of this embodiment includes a reinforcing plate 9 made of a material having gas permeability such as expanded metal or metal mesh on the cathode electrode 6 side, and maintains gas permeability to the cathode electrode 6. However, the mechanical strength is further increased.

  The separator 4 is made of a metal material such as stainless steel, and is a planar rectangular member corresponding to the cell structure 3 and is formed into a reversed front and back shape having irregularities by pressing. In the fuel cell FC, one separator 4 of the pair of separators 4 and 4 forms a cathode gas (oxygen-containing gas / air) circulation region G2 between the cell structure 3 and the cathode electrode 6 side. . The other separator 4 forms an anode gas (hydrogen-containing gas / hydrogen gas) flow region G1 between the cell structure 3 and the anode electrode 7 side.

  As described above, the fuel cells FC share the separator 4 between them in the fuel cell stack FS. For this reason, each shared separator 4 forms a cathode gas flow region G2 on one side which is the upper side in FIG. 2, and forms an anode gas flow region G1 on the other side which is the lower side in FIG. Thus, both distribution regions G1 and G2 are separated. Each distribution area | region G1, G2 is an area | region where only each gas can distribute | circulate.

  Here, an anode gas supply manifold hole H1 and a cathode gas discharge manifold hole H2 are formed in one short side portion of the frame 2 of the cell structure 3 and the separator 4, respectively. In addition, an anode gas discharge manifold hole H3 and a cathode gas supply manifold hole H4 are formed in the other short side portion, respectively. These manifold holes H1 to H4 form manifolds that communicate with each other and allow fuel gas and air to flow in a state where the cell structure 3 and the separator 4 are stacked.

  As shown in FIG. 1, in the fuel cell stack FS, end plates E1 and E2 are arranged above and below the stack of fuel cells FC via current collecting plates C1 and C2. The fuel cell stack FS restrains the stack by connecting the end plates E1 and E2 on both sides with bolts and nuts. For connection of the end plates E1 and E2, a spring for applying a stacking load is disposed as necessary. The manifold plates H1 to H4 are also formed in the current collector plates C1 and C2 and one end plate E2.

  In the fuel cell stack FS, a seal member S indicated by a dotted line in FIG. 1 is disposed between the members. The seal member S includes a member disposed between the peripheral portions of the cell structure 3 and the separator 4 and a member disposed around the manifold holes H1 to H4. Hereinafter, the seal member S will be specifically described.

  That is, the fuel cell FC includes an endless seal member S that hermetically joins at least the peripheral portions of the cell structure 3 and each separator 4. As shown in FIGS. 2 and 3, the seal member S is disposed in a seal groove G formed along the outer periphery of the separator 4, and the main line portion Sa continuous along the peripheral edge portion and the main line portion Sa And an increase portion Sb that partially increases the volume. The main line portion Sa has substantially the same cross-sectional shape in the continuous direction, and a molding error is within an allowable range. And the sealing member S is the structure which has arrange | positioned the increase part Sb with the predetermined space | interval with respect to main line part Sa.

  Further, in the fuel cell FC of this embodiment, the increasing portion Sb of the seal member S protrudes from the main line portion Sa in the in-plane direction (direction along the surface) of the separator 4, and in particular, the main line portion Sa is linear. In addition, the increased portion Sb protrudes to the outer peripheral side of the separator 4 (lower side in the enlarged view of FIG. 3). In the seal member S, the main line portion Sa and the increase portion Sb are made of the same material.

  Here, the sealing member S is, for example, a mixture of an inorganic material such as glass and a binder, and is baked after the assembly of the fuel cell FC so that the cell structure 3 and the separator 4 are hermetically sealed. To join. Note that the seal member S contracts due to scattering of the binder and the like during firing. Such a sealing member S has a property of maintaining airtightness between the members by being softened by heat at the time of operation of the fuel cell FC, for example, and returning to an initial cured state after the operation is stopped.

  In the fuel cell FC having the above-described configuration, the sealing member S is not configured to have a constant cross-sectional area in the continuous direction, but is configured such that increasing portions Sb that partially increase the volume of the main line portion Sa are arranged at predetermined intervals. The main line portion Sa is in a state of being divided into a plurality of short lines by each of the increasing portions Sb. For this reason, in the fuel cell FC, even when the seal member S contracts due to firing at the time of manufacture, no stress is exerted on the entire main line portion Sa, that is, no cumulative stress is generated, and as indicated by a white arrow in FIG. In addition, a sealing material is replenished from the increasing portion Sb to the main line portion Sa.

  As a result, the fuel cell FC can prevent the seal member S from being damaged during the production, such as cracks. Further, in the fuel cell stack FS formed by stacking the fuel cells FC described above, a sufficient sealing performance against the reaction gas (fuel gas and oxidant gas) is obtained by the seal member S without damage, and stable power generation is achieved. Can contribute.

  In addition, in order to prevent the crack at the time of baking, etc., it is also considered that a sealing member enlarges a cross-sectional area over the full length. However, in this case, more sealing members are required, the accumulated stress generated in the sealing members is increased, and the scattering of the binder and the like is insufficient. On the other hand, the above-described sealing member S does not generate accumulated stress, and the binder and the like are sufficiently scattered during firing, so that the composition has an excellent sealing performance.

  In the fuel cell FC, the increasing portion Sb of the seal member S is protruded from the main line portion Sa in the in-plane direction of the separator 4, so that the thickness of the seal member S is constant. Such a seal member S can be formed by screen printing or the like, and when the cell structure 3 and the separator 4 are overlapped, the seal line S is favorably maintained without causing a partial collapse. be able to.

  Further, in the fuel cell FC, the main line portion Sa is linear, and the increasing portion Sb protrudes to the outer peripheral side of the separator 4, thereby preventing a side flow of the reaction gas indicated by an arrow in FIG. 3. Can do. That is, when the increasing portion Sb is provided on the inner side of the sealing member S contrary to the illustrated example, a side flow of the reaction gas occurs between the increasing portions Sb, that is, a useless gas flow that does not contribute to power generation occurs. On the other hand, the sealing member S described above prevents the side flow of the reaction gas, and there is no fear that the increasing portion Sb hinders the gas flow.

  Further, when firing the sealing member S interposed between the cell structure 3 and the separator 4, the fuel cell FC described above, for example, from the manifold hole H <b> 2 on one side, as indicated by an arrow in FIG. 3. The sealing member S can be baked by circulating a high temperature gas through the manifold hole H4 on the other side. In this case, in the fuel cell FC, the upstream side of the high-temperature gas is a relatively high temperature region relative to the downstream side.

  Therefore, as a more preferred embodiment, the fuel cell FC is configured to place the increasing portion Sb of the seal member S in the high temperature region (upstream side) at the time of heating the cell structure 3 and the separator 4 with the seal member S interposed therebetween. Can be distributed in large numbers. Thereby, in the high temperature region where the shrinkage of the seal member S becomes more conspicuous, damage to the seal member S is more reliably prevented. The increasing portion Sb of the seal member S can also be provided in the seal member S disposed around the manifold holes H1 and H3 shown in FIG.

Second Embodiment
FIG. 4 is a view showing a second embodiment of the fuel cell of the present invention. In each embodiment described below, the same parts as those in the previous embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the seal member S of the fuel cell shown in FIG. 4, the increasing portion Sb protrudes from the main line portion Sa in the in-plane direction of the separator 4. In particular, the main line portion Sa has a zigzag shape, and the increasing portion Sb The zigzag corners of the main line portion Sa are provided.

  Even in the above fuel cell, as in the previous embodiment, the main line portion Sa is divided into a plurality of short lines by each of the increasing portions Sb, and the seal member S shrinks due to firing during manufacturing. In addition, no stress is exerted on the entire main line portion Sa, that is, no cumulative stress is generated, and a seal material is replenished from the increased portion Sb to the main line portion Sa as indicated by white arrows in FIG. As a result, the fuel cell FC can prevent the seal member S from being damaged during the production, such as cracks.

  In addition, the fuel cell FC has a zigzag main line portion Sa and an increased portion Sb provided at the corner of the main line portion Sa. Therefore, the main line portion Sa is made longer to secure a wide sealing region. Can do.

<Third Embodiment>
In the fuel cell sealing member S shown in FIG. 5, the main line portion Sa is composed of a plurality of divided short line portions Sc, and the increasing portion Sb is a portion where the ends of the respective short line portions Sc are joined together. The seal member S in the illustrated example has a configuration in which the short line portions Sc are alternately arranged on the left and right of the center line in the continuous direction of the seal member S, and the end portions that are joint portions of the short line portions Sc are increased portions Sb. It is. The sealing member S in the illustrated example joins the ends of the short line portions Sb on a plane.

  In the fuel cell described above, since the main line portion Sa is formed by joining the plurality of divided short line portions Sc, even when the seal member S contracts due to firing at the time of manufacture, the entire main line portion Sa is stressed. In addition, as indicated by a white arrow in FIG. 5, the sealing material is replenished from the increased portion Sb to the main line portion Sa. As a result, the fuel cell FC can prevent the seal member S from being damaged during the production, such as cracks. In addition, since the fuel cell FC employs a plurality of short line portions Sc, it can be easily applied to various forms of seal lines.

<Fourth and Fifth Embodiments>
In the fuel cell sealing member S shown in FIG. 6, the main line portion Sa is composed of a plurality of divided short line portions Sc, and the increasing portion Sb is a portion where the ends of the respective short line portions Sc are joined together. In the third embodiment, the configuration in which the ends of the respective short line portions Sc are joined on a plane has been described. On the other hand, the sealing members S of the fourth and fifth embodiments are joined by overlapping the ends of the respective short line portions Sc in the vertical direction.

  In the seal member S of the fourth embodiment shown in FIG. 6A, a plurality of divided short line portions Sc are arranged in a zigzag shape to form the main line portion Sa, and the ends of the short line portions Sc are moved up and down. This is overlapped with the increase portion Sb, that is, the increase portion Sb that partially increases the volume of the main line portion Sa.

  In addition, the seal member S of the fifth embodiment shown in FIG. 6B has a plurality of divided short line portions Sc arranged in a straight line to form a main line portion Sa, and ends of the short line portions Sc. Are stacked on top and bottom to form the increased portion Sb.

  Furthermore, in 4th and 5th embodiment, as shown in FIG. 6, the separator 4 has the seal groove G of the shape corresponding to arrangement | positioning of the seal member S. As shown in FIG. The illustrated seal groove G has a zigzag shape or a linear shape as a shape corresponding to the arrangement of the seal member S, and has a width dimension larger than the width of the seal member S, and the seal member S is disposed therein. It is.

  In each of the fuel cells, since the end portions of the respective short line portions Sc are vertically stacked in the seal member S, when the cell structure 3 and the separator 4 are joined, the increasing portion Sb is crushed, In this state, the sealing material is fired. Even in these fuel cells, even if the seal member S contracts due to firing at the time of manufacture, the entire main line portion Sa is not stressed, and the main line portion Sa is replenished with the sealing material from the increasing portion Sb. Thereby, the fuel cell can prevent damage such as cracks from occurring in the seal member S during manufacturing.

  Further, in each of the above fuel cells, since the seal groove G having a shape corresponding to the arrangement of the seal member S is formed in the separator 4 and the seal member S is arranged in the seal groove G, the cell structure 3 and the separator 4 is joined to crush the increased portion Sb, the lateral extension of the increased portion Sb can be retained in the seal groove G, and a good seal line can be formed.

<Sixth Embodiment>
FIG. 7 is a diagram showing various cross-sectional shapes of the seal member S. In the drawing, the shape of the main line portion Sa of the sealing material S is shown, and the illustration of the increasing portion is omitted.

  That is, as a more preferred embodiment, the fuel cell of the present invention can be configured such that the seal member S has a shape that promotes deformation in the thickness direction in a cross section that intersects the continuous direction. The shape that promotes deformation is a shape that has a low elastic modulus, and in short, is a shape that is easily deformed in the thickness direction.

  In this embodiment, the seal member S shown in FIG. 7A has an arc shape with the upper side as the outer peripheral side. The seal member S shown in FIG. 7B has a shape having chamfers R on both upper sides of the rectangular main body. The seal member S shown in FIG. 7C has a triangular shape with the upper side as a vertex.

  The seal member S shown in FIG. 7D has a rectangular shape with the upper side as a hypotenuse. The seal member S shown in FIG. 7E has a triangular protrusion T on the upper side of the rectangular main body. The seal member S shown in FIG. 7F has a triangular recess Q at the center of the upper side of the rectangular main body. And the sealing member S shown to FIG. 7 (G) has the semicircle recessed part Q in the upper side center of a rectangular main body.

  FIG. 8 is a graph showing the relationship between the load and the compression amount for the sealing member S having a rectangular cross-sectional shape and the sealing member S having a circular cross-sectional shape as shown in FIG. In this graph, the load F1 is the minimum load (minimum load for sufficient firing) necessary to develop the sealing property. The load F2 is a limit load that the seal member S can withstand.

  As is apparent from the above graph, in the range from the minimum load F1 to the limit load F2, the arc shape indicated by the solid line in the figure rather than the compression amount (L2-L1) of the rectangular seal member S indicated by the dotted line in the figure. The amount of compression (L2-L1) of the sealing member S is larger. In this way, the amount of compression is larger than that of the rectangular seal member S, as well as the arc-shaped seal member S, as well as the seal members S shown in FIGS.

  Like the previous embodiments, the fuel cell including the above-described seal member S can prevent the seal member S from being damaged such as cracks during manufacturing, and the seal member S is thick. Since it is easily deformed in the direction, when sandwiched between the cell structure 3 and the separator 4 and baked, the variation in the depth of the seal groove G is absorbed and the gap between the two is hermetically sealed.

<Seventh and Eighth Embodiments>
In the fuel cell of the seventh embodiment shown in FIG. 9A, at least one of the cell structure (3) and the separator (4) has a sealing region between the main body and the sealing region. A displacement promoting part F for displacement is provided. In the illustrated example, in the frame 2 of the cell structure 3, the displacement promoting portion having a thickness relatively smaller than other portions between the main body portion A and the seal region 2 </ b> B that is the peripheral portion of the main body portion A. F.

  The fuel cell having the above configuration can obtain the same effects as those of the previous embodiments by the seal member S. In the fuel cell, since the frame 2 of the cell structure 3 is easily displaced in the seal region 2B by the displacement promoting portion F, the seal member S is sandwiched between the cell structure 3 and the separator 4 and fired. In addition, the gap between the two can be hermetically sealed without being affected by variations in the depth of the seal groove G.

  In the fuel cell of the eighth embodiment shown in FIG. 9B, an auxiliary material 10 that is softer than the seal member S is provided between at least one of the cell structure (3) and the separator (4) and the seal member s. I have. In the illustrated example, an auxiliary material is interposed between the frame 2 of the cell structure 3 and the seal member S. For the auxiliary material 10, a contact material such as glass paste can be used.

  The fuel cell having the above configuration can obtain the same effects as those of the previous embodiments by the seal member S. And since the fuel cell has arrange | positioned the auxiliary | assistant material 10 softer than the sealing member S between the flame | frame 2 and the sealing member S of the cell structure 3, from the right figure in FIG.9 (B) to the left figure. From the initial assembly of the cell structure 3 and the separator 4, the auxiliary member 10 is in contact with the frame 2 of the cell structure 3 and is crushed so that the seal member S is transferred.

  Thus, when the fuel cell is sandwiched between the cell structure 3 and the separator 4 and fired, the fuel cell does not depend on the variation in the depth of the seal groove G, and does not affect the airtightness between the two. In addition, since the amount of compression and shrinkage of the seal member S is reduced by the amount of the auxiliary material 10, a decrease in the density (glass density) of the seal member S can be prevented.

  The configuration of the fuel cell according to the present invention is not limited to the above embodiments, and the configuration can be changed as appropriate without departing from the gist of the present invention. The shape and arrangement of the increasing portion with respect to the main line portion can be changed, or the configurations of the embodiments can be combined.

DESCRIPTION OF SYMBOLS 1 Power generation area of cell structure 2 Frame of cell structure 2A Main body part 2B Seal area 3 Cell structure 4 Separator 5 Electrolyte 6 Anode electrode 7 Cathode electrode 10 Auxiliary material F Displacement promotion part FC Fuel cell FS Fuel cell stack S Seal member Sa Main line part Sb Increase part Sc Short line part

Claims (11)

A cell structure having a structure in which an electrolyte is sandwiched between an anode electrode and a cathode electrode;
A pair of separators disposed on both sides of the cell structure;
A seal member for airtightly bonding between at least the peripheral portions of the cell structure and each separator;
The seal member includes a main line portion that is continuous along the peripheral edge portion and has the same cross-sectional shape in the continuous direction, and an increasing portion that partially increases the volume of the main line portion. A fuel cell characterized in that the increasing portions are arranged at predetermined intervals.   2. The fuel cell according to claim 1, wherein the increasing portion of the seal member protrudes from the main line portion in the in-plane direction of the separator.   3. The fuel cell according to claim 2, wherein a main line portion of the seal member is linear and the increasing portion protrudes toward an outer peripheral side of the separator.   3. The fuel cell according to claim 1, wherein the main line portion of the seal member has a zigzag shape, and the increasing portion is provided in a zigzag corner of the main line portion.   The main line portion of the seal member is composed of a plurality of divided short wire portions, and the increasing portion is a portion where ends of the short wire portions are joined to each other. Fuel cell.   The fuel cell according to any one of claims 1 to 5, wherein the seal member has a shape that promotes deformation in the thickness direction in a cross section intersecting the continuous direction.   At least one of the cell structure and the separator has a displacement promoting portion that displaces the seal region with respect to the main body portion between the main body portion and a seal region that is a peripheral portion thereof. Item 7. The fuel cell according to any one of Items 1 to 6.   The fuel cell according to any one of claims 1 to 7, further comprising an auxiliary material softer than the seal member between at least one of the cell structure and the separator and the seal member. .   9. The increasing portion of the sealing member is distributed in a relatively large amount in a region where the temperature is relatively high during heating of the cell structure and the separator interposed with the sealing member. The fuel cell according to any one of the above.   The said separator has the seal groove of the shape corresponding to arrangement | positioning of a seal member, The seal member is arrange | positioned in the said seal groove, The any one of Claims 1-9 characterized by the above-mentioned. Fuel cell. It has the structure which laminated the fuel cell of any one of Claims 1-10,
A fuel cell stack, wherein adjacent fuel cells constitute respective fuel cells by sharing a separator between them.

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