JP6090842B2 - Fuel cell stack - Google Patents

Description

  The present invention comprises a fuel cell in which an electrolyte membrane and electrode structure each provided with an electrode and a separator are laminated on both sides of the electrolyte membrane, and a terminal plate at both ends in the stacking direction of the plurality of fuel cells. The present invention relates to a fuel cell stack in which an insulator and an end plate are disposed.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode on one side and a cathode electrode on the other side of an electrolyte membrane made of a polymer ion exchange membrane is provided as a pair. It is pinched by the separator. In general, a plurality of fuel cells are stacked to form a fuel cell stack. The fuel cell stack is mounted on, for example, a fuel cell electric vehicle and used as an in-vehicle fuel cell system.

  In the fuel cell stack, a terminal plate, an insulator, and an end plate are sequentially stacked at both ends in the stacking direction of the stacked body in which a plurality of fuel cells are stacked. For example, in the fuel cell stack disclosed in Patent Document 1, at least one end in the stacking direction of the stacked body is located between the stacked body and the terminal plate, so-called in correspondence with the fuel cell, A dummy cell is provided. The dummy cell uses a metal plate in place of the electrolyte membrane, and water generated by power generation is not generated. Therefore, the dummy cell itself can function as a heat insulating layer.

Japanese Patent No. 4727972

  By the way, in the fuel cell stack described above, at least one of the separator or the electrolyte membrane / electrode structure, a fuel gas inlet communication hole that is a reaction gas communication hole penetrating in the stacking direction of the fuel cell, an oxidant gas inlet communication hole, In many cases, an internal manifold type fuel cell is provided in which a fuel gas outlet communication hole and an oxidant gas outlet communication hole are provided, and a cooling medium inlet communication hole and a cooling medium outlet communication hole are provided penetrating in the stacking direction. .

  At that time, for example, a separator in which positioning knock holes, the outer shape of the buffer portion, the shape of the seal member, and the like are provided at point-symmetric positions in addition to the communication holes is employed. For this reason, even if the fuel cells are stacked in a posture rotated (inverted) 180 degrees in the plane from a desired posture, terminal plates, insulators, and end plates may be disposed at both ends in the stacking direction.

  However, different configurations may be employed, for example, between the buffer part on the inlet side and the buffer part on the outlet side, for example, due to the relationship between the distribution of the reaction gas and the cooling medium and the pressure loss balance. In addition, each communication hole may have a configuration in which the opening area is different between the inlet side and the outlet side. Therefore, when the fuel cell is assembled in an inverted state, there is a problem that desired power generation performance cannot be obtained.

  The present invention solves this type of problem, and an object of the present invention is to provide a fuel cell stack that can easily and reliably prevent erroneous assembly of a fuel cell with a simple configuration.

The present invention has a fuel cell in which an electrolyte membrane and electrode structure each provided with an electrode and a separator are laminated on both sides of the electrolyte membrane, and a plurality of the fuel cells are laminated. A reaction gas flow path for supplying a reaction gas that is at least a fuel gas or an oxidant gas along the electrode surface, and a plurality of embosses having a height H, communicated with the inlet side of the reaction gas flow path outside the power generation region An outlet buffer for uniformly flowing the reaction gas; and a plurality of embosses having a height of H, and an outlet buffer for evenly flowing the reaction gas in communication with the outlet side of the reaction gas channel outside the power generation region. And a terminal plate, an insulator, and an end plate are disposed at both ends in the stacking direction of the fuel cell.

In this fuel cell stack, the terminal plate has a smaller plane size than the insulator, and is accommodated in a recess formed in the insulator. The insulator corresponds to a region where the plurality of embossments in the inlet buffer portion of the separator do not exist at a portion in direct contact with the separator constituting the end portion of the fuel cell stack, and is high on the inlet buffer portion side. The outlet side backing portion formed to protrude by a height S on the outlet buffer portion side, corresponding to the region where the plurality of embosses do not exist in the outlet buffer portion, and the inlet side backing portion formed to protrude by the length S And the inlet side backing portion and the outlet side backing portion are configured to be asymmetrical, and at least of the plurality of embossments on the inlet side backing portion and the outlet buffer portion side. One is configured point-symmetrically, and at least one of the plurality of embosses on the outlet side backing portion and the inlet buffer portion side is configured point-symmetrically and satisfies the relationship of S <H. .

Further, in this fuel cell stack, the separator is formed with a reaction gas inlet communication hole and a reaction gas outlet communication hole through which the reaction gas flows in the stacking direction, and the reaction gas channel and the reaction gas inlet communication hole are formed in the separator. The inlet buffer portion to be connected, and the outlet buffer portion connected to the reaction gas flow path and the reaction gas outlet communication hole each have a line-shaped convex portion having a height T, and the inlet buffer portion It is preferable that the line-shaped convex portion and the line-shaped convex portion of the outlet buffer portion are configured to be asymmetric with respect to each other and satisfy the relationship S + T = H.

  Further, in this fuel cell stack, the separator is formed with a cooling medium inlet communication hole and a cooling medium outlet communication hole for circulating the cooling medium in the stacking direction, and at least a reaction gas inlet communication hole, a reaction gas outlet communication hole, It is preferable that the cooling medium inlet communication hole and the cooling medium outlet communication hole are provided at point-symmetric positions.

  According to the present invention, the insulator is provided with an inlet-side backing portion corresponding to the inlet buffer portion and an outlet-side backing portion corresponding to the outlet buffer portion at a portion contacting the adjacent separator, and the inlet The side back receiving portion and the outlet side back receiving portion are configured to be asymmetric with respect to a point.

  For this reason, when the separator is reversed (rotated 180 ° with the in-plane center as a fulcrum), the separator inlet buffer portion and outlet buffer portion and the insulator outlet side backing portion and inlet side backing portion are stacked in the stacking direction. Do not overlap. Accordingly, it is possible to easily and reliably prevent erroneous assembly of the fuel cell with a simple configuration.

1 is a partially exploded schematic perspective view of a fuel cell stack according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the fuel cell stack taken along line II-II in FIG. 1. It is a principal part disassembled perspective explanatory drawing of the electric power generation unit which comprises the said fuel cell stack. FIG. 4 is a sectional view of the fuel cell stack taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional explanatory view of the fuel cell stack taken along line VV in FIG. 3. It is front explanatory drawing of the 1st metal separator which comprises the said electric power generation unit. It is explanatory drawing of one surface of the 2nd metal separator which comprises the said electric power generation unit. It is explanatory drawing of the other surface of the said 2nd metal separator. It is the IX-IX sectional view taken on the line of the said 2nd metal separator in FIG. It is explanatory drawing of one surface of the 1st electrolyte membrane and electrode structure which comprises the said electric power generation unit. It is explanatory drawing of one surface of the 2nd electrolyte membrane and electrode structure which comprises the said electric power generation unit. It is front explanatory drawing of one insulator which comprises the said fuel cell stack.

  As shown in FIGS. 1 and 2, a fuel cell stack 10 according to an embodiment of the present invention includes a stacked body in which a plurality of power generation units (fuel cells) 12 are stacked in a standing position in a horizontal direction (arrow A direction). 13 is provided. In addition, the laminated body 13 may laminate | stack the several electric power generation unit 12 in a gravitational direction (arrow C direction).

  A terminal plate 100a, an insulator 102a, and an end plate 104a are sequentially arranged at one end in the stacking direction (arrow A direction) of the stacked body 13 toward the outside. At the other end in the stacking direction of the stacked body 13, a terminal plate 100b, an insulator 102b, and an end plate 104b are sequentially disposed outward.

  The fuel cell stack 10 is, for example, integrally held by a box-like casing (not shown) including end plates 104a and 104b configured in a rectangular shape as end plates, or a plurality of tie rods extending in the arrow A direction. (Not shown) are integrally clamped and held.

  As shown in FIGS. 2 to 5, the power generation unit 12 includes a first metal separator 14, a first electrolyte membrane / electrode structure 16 a, a second metal separator 18, a second electrolyte membrane / electrode structure 16 b, and a third metal. A separator 20 is provided. The first metal separator 14, the first electrolyte membrane / electrode structure 16a, the second metal separator 18, the second electrolyte membrane / electrode structure 16b, and the third metal separator 20 are stacked along the horizontal direction (arrow A direction). In addition, the electrode surface has a vertically long shape along the direction of gravity and a horizontally long shape in the horizontal direction (arrow B direction).

  The first metal separator 14, the second metal separator 18, and the third metal separator 20 are, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a horizontally long metal whose surface has been subjected to anticorrosion treatment. Consists of plates. The first metal separator 14, the second metal separator 18, and the third metal separator 20 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing a metal thin plate into a wave shape.

  A carbon separator may be used instead of the metal separator. As will be described later, the first metal separator 14, the second metal separator 18, and the third metal separator 20 are provided at positions where the communication holes, the buffer portion outer shape, the seal member shape, and the like are point-symmetric. Point symmetry refers to a relationship in which the positions overlap by rotating 180 ° in a plane.

  As shown in FIG. 3, specifically, the length of the first metal separator 14, the second metal separator 18, and the third metal separator 20 is provided at one edge of the power generation unit 12 in the long side direction (arrow B direction). One end edge in the side direction communicates with each other in the direction of arrow A, and an oxidant gas inlet communication hole 22a for supplying an oxidant gas, for example, an oxygen-containing gas, and a fuel gas, for example, a hydrogen-containing gas. A fuel gas outlet communication hole 24b for discharging is provided.

  The other end edge of the power generation unit 12 in the long side direction (arrow B direction) communicates with each other in the arrow A direction, and discharges the fuel gas inlet communication hole 24a for supplying fuel gas and the oxidant gas. For this purpose, an oxidant gas outlet communication hole 22b is provided.

  A pair of cooling medium inlets for supplying a cooling medium in close proximity to the oxidant gas inlet communication hole 22a and communicating with each other in the direction of the arrow A at both end edges in the short side direction (arrow C direction) of the power generation unit 12 A communication hole 25a is provided. A pair of cooling medium outlet communication holes 25b for communicating with each other in the direction of the arrow A to discharge the cooling medium are provided at both end edges in the short side direction of the power generation unit 12 and in communication with each other in the direction of arrow A. .

  As shown in FIG. 6, the surface 14a of the first metal separator 14 facing the first electrolyte membrane / electrode structure 16a is connected to the oxidant gas inlet communication hole 22a and the oxidant gas outlet communication hole 22b. An oxidant gas flow path 26 is formed.

  The first oxidant gas channel 26 has a plurality of wave-like channel grooves (or linear channel grooves) 26 a extending in the direction of arrow B, and the vicinity of the inlet and the outlet of the first oxidant gas channel 26. In the vicinity, an inlet buffer portion 28a and an outlet buffer portion 28b are provided.

  The inlet buffer portion 28a includes a plurality of embosses 28ae and one or more line-shaped convex portions (guide vanes) 28ag. The outlet buffer portion 28b has a plurality of embosses 28be and one or more line-shaped convex portions (guide vanes) 28bg. The line-shaped protrusions 28ag and the line-shaped protrusions 28bg are provided in consideration of the distribution of the oxidant gas and the pressure loss balance, and are asymmetric with respect to each other (in addition, different lengths and different numbers as necessary). Configured. When the first metal separator 14 is rotated (inverted) by 180 °, the line-shaped protrusions 28ag and the line-shaped protrusions 28bg are arranged at positions that do not overlap each other.

  Between the inlet buffer portion 28a and the oxidant gas inlet communication hole 22a, a plurality of inlet connection grooves 30a constituting a bridge portion are formed. A plurality of outlet connection grooves 30b constituting a bridge portion are formed between the outlet buffer portion 28b and the oxidizing gas outlet communication hole 22b.

  As shown in FIG. 3, a cooling medium flow path 38 that connects the cooling medium inlet communication hole 25 a and the cooling medium outlet communication hole 25 b is formed on the surface 14 b of the first metal separator 14. The cooling medium channel 38 is formed by overlapping the back surface shape of the first oxidant gas channel 26 and the back surface shape of the second fuel gas channel 58 described later.

  As shown in FIG. 7, the first fuel gas that communicates the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b to the surface 18a of the second metal separator 18 facing the first electrolyte membrane / electrode structure 16a. A flow path 40 is formed. The first fuel gas channel 40 has a plurality of wave-like channel grooves (or linear channel grooves) 40a extending in the direction of arrow B. A plurality of supply holes 42a are formed in the vicinity of the fuel gas inlet communication hole 24a, and a plurality of discharge holes 42b are formed in the vicinity of the fuel gas outlet communication hole 24b.

  As shown in FIG. 8, the surface 18b of the second metal separator 18 facing the second electrolyte membrane / electrode structure 16b communicates with the oxidant gas inlet communication hole 22a and the oxidant gas outlet communication hole 22b. An oxidant gas flow path 50 is formed. The second oxidizing gas channel 50 has a plurality of wave-like channel grooves (or linear channel grooves) 50a extending in the direction of arrow B.

  An inlet buffer portion 52a and an outlet buffer portion 52b are provided in the vicinity of the inlet and the outlet of the second oxidizing gas channel 50. The inlet buffer 52a has a plurality of embosses 52ae and one or more line-shaped protrusions (guide vanes) 52ag. The outlet buffer 52b has a plurality of embosses 52be and one or more line-shaped convex portions (guide vanes) 52bg.

  The line-shaped protrusions 52ag and the line-shaped protrusions 52bg are provided in consideration of the distribution of the oxidant gas and the pressure loss balance, respectively, and are astigmatic with respect to each other (and with different lengths and different numbers as necessary). Configured.

  When the second metal separator 18 is rotated (inverted) by 180 °, the line-shaped convex portions 52ag and the line-shaped convex portions 52bg are arranged at positions that do not overlap each other. As shown in FIG. 9, the embossing 52ae is set higher in the stacking direction (arrow A direction) by the height S than the line-shaped convex portion 52ag. Similarly, the embossing 52be is set higher than the line-shaped convex portion 52bg by the height S.

  Contrary to the above, the line-shaped convex portions 52ag may be set higher in the stacking direction than the embossed 52ae. Further, the inlet buffer portion 28a and the outlet buffer portion 28b of the first metal separator 14 may be configured similarly to the inlet buffer portion 52a and the outlet buffer portion 52b. Furthermore, the present invention can be applied to at least one of the end plate 104a side or the end plate 104b side.

  As shown in FIG. 8, a plurality of inlet connection grooves 53a constituting a bridge portion are formed between the inlet buffer portion 52a and the oxidant gas inlet communication hole 22a. A plurality of outlet connecting grooves 53b constituting a bridge portion are formed between the outlet buffer portion 52b and the oxidizing gas outlet communication hole 22b.

  As shown in FIG. 3, the second fuel gas flow communicating with the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b is formed on the surface 20a of the third metal separator 20 facing the second electrolyte membrane / electrode structure 16b. A path 58 is formed. The second fuel gas channel 58 has a plurality of wave-like channel grooves (or linear channel grooves) 58a extending in the direction of arrow B.

  A plurality of supply holes 60a are formed in the vicinity of the fuel gas inlet communication hole 24a, and a plurality of discharge holes 60b are formed in the vicinity of the fuel gas outlet communication hole 24b. As shown in FIGS. 3 and 4, the supply hole 60 a is disposed on the inner side (fuel gas flow path side) of the second metal separator 18 than the supply hole 42 a, while the discharge hole 60 b It arrange | positions inside the discharge hole part 42b of the metal separator 18 (fuel gas flow path side).

  A part of the coolant flow path 38, which is the back surface shape of the second fuel gas flow path 58, is formed on the surface 20 b of the third metal separator 20. A cooling medium flow path 38 is integrally provided on the surface 20 b of the third metal separator 20 by laminating the surface 14 b of the first metal separator 14 adjacent to the third metal separator 20.

  A first seal member 68 is integrally formed on the surfaces 14 a and 14 b of the first metal separator 14 around the outer peripheral edge portion of the first metal separator 14. A second seal member 70 is integrally formed around the outer peripheral edge of the second metal separator 18 on the surfaces 18a and 18b of the second metal separator 18, and the surfaces 20a and 20b of the third metal separator 20 are integrally formed. The third seal member 72 is integrally formed around the outer peripheral edge of the third metal separator 20.

  Examples of the first seal member 68, the second seal member 70, and the third seal member 72 include EPDM, NBR, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, or acrylic rubber. A sealing material having elasticity such as a sealing material, a cushioning material, or a packing material is used.

  As shown in FIG. 6, the first seal member 68 includes an oxidant gas inlet communication hole 22 a and an oxidant gas outlet communication hole 22 b on the surface 14 a of the first metal separator 14, and the first oxidant gas flow path 26. A first convex seal portion 68a communicating with the outer periphery of the first convex seal portion 68a. As shown in FIG. 3, the first seal member 68 communicates the outer periphery of the cooling medium inlet communication hole 25 a, the cooling medium outlet communication hole 25 b, and the cooling medium flow path 38 on the surface 14 b of the first metal separator 14. It has two convex seal portions 68b.

  As shown in FIG. 7, the second seal member 70 surrounds the supply hole portion 42 a and the discharge hole portion 42 b and the first fuel gas flow path 40 on the surface 18 a of the second metal separator 18 and communicates them. The first convex seal portion 70a is provided.

  As shown in FIG. 8, the second seal member 70 communicates the outer periphery of the oxidant gas inlet communication hole 22 a and the oxidant gas outlet communication hole 22 b with the second oxidant gas flow path 50 on the surface 18 b. It has two convex seal parts 70b.

  As shown in FIG. 3, the third seal member 72 surrounds the supply hole portion 60 a and the discharge hole portion 60 b and the second fuel gas channel 58 on the surface 20 a of the third metal separator 20, and communicates these. A first convex seal portion 72a.

  The third seal member 72 includes a second convex seal portion 72b that communicates the outer periphery of the cooling medium inlet communication hole 25a, the cooling medium outlet communication hole 25b, and the cooling medium flow path 38 on the surface 20b of the third metal separator 20. Have.

  As shown in FIG. 2, the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b include, for example, a solid polymer electrolyte membrane 74 in which a perfluorosulfonic acid thin film is impregnated with water, A cathode electrode 76 and an anode electrode 78 sandwiching the solid polymer electrolyte membrane 74 are provided. The cathode electrode 76 constitutes a stepped MEA having a planar dimension smaller than that of the anode electrode 78 and the solid polymer electrolyte membrane 74.

  The cathode electrode 76, the anode electrode 78, and the solid polymer electrolyte membrane 74 may be set to have the same planar dimension, and the anode electrode 78 is determined from the planar dimension of the cathode electrode 76 and the solid polymer electrolyte membrane 74. May have small planar dimensions.

  The cathode electrode 76 and the anode electrode 78 have a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles having a platinum alloy supported on the surface are uniformly applied to the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) to be formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 74.

  The first electrolyte membrane / electrode structure 16a is located outside the terminal portion of the cathode electrode 76, and the first resin frame member 80 is integrally formed on the outer peripheral edge of the solid polymer electrolyte membrane 74 by, for example, injection molding or the like. Is done. The second electrolyte membrane / electrode structure 16b is located outside the terminal portion of the cathode electrode 76, and the second resin frame member 82 is integrally formed on the outer peripheral edge of the solid polymer electrolyte membrane 74 by, for example, injection molding or the like. Is done. As a resin material constituting the first resin frame member 80 and the second resin frame member 82, for example, engineering plastics, super engineering plastics, etc. are adopted in addition to general-purpose plastics.

  As shown in FIG. 3, the inlet of the first resin frame member 80 on the cathode electrode 76 side is located between the oxidant gas inlet communication hole 22a and the inlet side of the first oxidant gas flow path 26. A buffer unit 84a is provided. An outlet buffer part 84b is provided between the oxidizing gas outlet communication hole 22b and the outlet side of the first oxidizing gas channel 26. The inlet buffer portion 84a and the outlet buffer portion 84b each have a plurality of embossments and a plurality of straight flow paths. The same applies to other buffer units described below.

  As shown in FIG. 10, the surface of the first resin frame member 80 on the anode electrode 78 side is provided with an inlet buffer portion 86a located between the fuel gas inlet communication hole 24a and the first fuel gas flow path 40. In addition, an outlet buffer portion 86b is provided between the fuel gas outlet communication hole 24b and the first fuel gas flow path 40.

  As shown in FIG. 3, the second resin frame member 82 provided in the second electrolyte membrane / electrode structure 16b has an oxidant gas inlet communication hole 22a and a second oxidant gas flow path on the surface on the cathode electrode 76 side. 50, an inlet buffer portion 88a is provided. An outlet buffer portion 88b is formed between the oxidant gas outlet communication hole 22b and the second oxidant gas flow path 50.

  On the surface of the second resin frame member 82 on the anode electrode 78 side, as shown in FIG. 11, an inlet buffer portion 90a is provided between the fuel gas inlet communication hole 24a and the second fuel gas flow path 58. It is done. An outlet buffer portion 90 b is provided between the fuel gas outlet communication hole 24 b and the second fuel gas flow path 58.

  When the power generation units 12 are stacked on each other, a cooling medium flow path is provided between the first metal separator 14 constituting one power generation unit 12 and the third metal separator 20 constituting the other power generation unit 12. 38 is formed.

  As shown in FIG. 1, second metal separators 18 are disposed at both ends in the stacking direction of the stacked body 13. Terminal portions 106a and 106b extending outward in the stacking direction are provided at substantially the center of the terminal plates 100a and 100b adjacent to the second metal separators 18 at both ends in the stacking direction. The terminal portions 106a and 106b are inserted into the insulating cylinder 108 and project outside the end plates 104a and 104b. The insulators 102a and 102b are made of an insulating material such as polycarbonate (PC) or phenol resin.

  Insulators 102a and 102b are provided with rectangular recesses 110a and 110b at the center, and holes 112a and 112b are formed at substantially the center of the recesses 110a and 110b. The terminal plates 100a and 100b are accommodated in the recesses 110a and 110b, and the terminal portions 106a and 106b of the terminal plates 100a and 100b are inserted into the holes 112a and 112b with the insulating cylinder 108 interposed therebetween.

  Hole portions 114a and 114b are formed coaxially with the hole portions 112a and 112b at substantially the center portions of the end plates 104a and 104b. The end plates 104a and 104b include an oxidant gas inlet communication hole 22a, a fuel gas inlet communication hole 24a, two cooling medium inlet communication holes 25a, an oxidant gas outlet communication hole 22b, a fuel gas outlet communication hole 24b, and two coolings. A medium outlet communication hole 25b is formed.

  An uneven portion corresponding to the uneven shape on the surface 18a side of the second metal separator 18 may be provided on the outer peripheral portion on the surface side in contact with the second metal separator 18 of the insulator 102a.

  As shown in FIG. 12, a concavo-convex shape portion 120 is provided on the surface side of the insulator 102 b in contact with the second metal separator 18 in correspondence with the concavo-convex shape on the surface 18 b side of the second metal separator 18. The uneven shape portion 120 corresponds to the inlet side backing portion 120a corresponding to the line-shaped convex portion 52ag constituting the inlet buffer portion 52a of the second metal separator 18 and the line-shaped convex portion 52bg constituting the outlet buffer portion 52b. And an outlet side back receiving portion 120b.

  As shown in FIG. 5, the inlet side backing portion 120 a is formed to protrude from the surface of the insulator 102 b by a height S corresponding to the step between the embossed 52 ae and the line-shaped convex portion 52 ag. Similarly, the outlet side backing portion 120b is formed to protrude from the surface of the insulator 102b by a height S. The inlet side backing portion 120a and the outlet side backing portion 120b are configured to be asymmetric with respect to each other.

  The operation of the fuel cell stack 10 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 22a via the end plate 104a, and a hydrogen gas is supplied to the fuel gas inlet communication hole 24a. Fuel gas such as contained gas is supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the pair of cooling medium inlet communication holes 25a.

  Therefore, as shown in FIGS. 3 and 5, the oxidant gas is supplied from the oxidant gas inlet communication hole 22a to the first oxidant gas flow path 26 of the first metal separator 14 through the inlet buffer portion 84a. The Part of the oxidant gas is introduced into the second oxidant gas flow path 50 of the second metal separator 18 from the oxidant gas inlet communication hole 22a through the inlet buffer portion 88a.

  The oxidant gas moves in the direction of arrow B (horizontal direction) along the first oxidant gas flow path 26 and is supplied to the cathode electrode 76 of the first electrolyte membrane / electrode structure 16a. It moves in the direction of arrow B along the gas flow path 50 and is supplied to the cathode electrode 76 of the second electrolyte membrane / electrode structure 16b.

  On the other hand, as shown in FIGS. 3 and 4, the fuel gas is supplied from the fuel gas inlet communication hole 24a to the inlet buffer part 86a through the supply hole part 42a. The fuel gas is supplied to the first fuel gas channel 40 of the second metal separator 18 through the inlet buffer portion 86a. Part of the fuel gas is supplied from the fuel gas inlet communication hole 24a through the supply hole 60a to the inlet buffer 90a. The fuel gas is supplied to the second fuel gas channel 58 of the third metal separator 20 through the inlet buffer unit 90a.

  The fuel gas moves in the direction of arrow B along the first fuel gas flow path 40 and is supplied to the anode electrode 78 of the first electrolyte membrane / electrode structure 16 a and along the second fuel gas flow path 58. It moves in the direction of arrow B and is supplied to the anode electrode 78 of the second electrolyte membrane / electrode structure 16b.

  Therefore, in the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b, the oxidizing gas supplied to each cathode electrode 76 and the fuel gas supplied to each anode electrode 78 are electrodes. Electricity is generated by being consumed by an electrochemical reaction in the catalyst layer.

  Next, the oxidant gas supplied to and consumed by the cathode electrodes 76 of the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b is communicated with the oxidant gas outlet from the outlet buffer portions 84b and 88b. It is discharged into the hole 22b (see FIG. 3).

  The fuel gas consumed by being supplied to the anode electrode 78 of the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b passes through the discharge holes 42b, 60b from the outlet buffer portions 86b, 90b. It is discharged into the fuel gas outlet communication hole 24b.

  On the other hand, the cooling medium supplied to the pair of left and right cooling medium inlet communication holes 25a is supplied to the cooling medium flow path 38 from each cooling medium inlet communication hole 25a, as shown in FIG. The cooling medium once flows in the direction of the arrow C and then moves in the direction of the arrow B to cool the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b. This cooling medium moves outward in the direction of arrow C, and is then discharged into the pair of cooling medium outlet communication holes 25b.

  In this case, in this embodiment, as shown in FIG. 12, the line-shaped convex part 52ag which comprises the inlet buffer part 52a of the said 2nd metal separator 18 is provided in the surface side which contacts the 2nd metal separator 18 of the insulator 102b. And an outlet side backing portion 120b corresponding to the line-shaped convex portion 52bg constituting the outlet buffer portion 52b of the second metal separator 18 are provided.

  The inlet-side backing portion 120a and the outlet-side backing portion 120b are formed so as to protrude from the surface of the insulator 102b by a height S and are asymmetric with respect to each other. On the other hand, as shown in FIG. 9, the embossing 52ae is set higher in the stacking direction by the height S than the line-shaped convex portion 52ag. Furthermore, the embossing 52be is set higher in the stacking direction by the height S than the line-shaped convex portion 52bg.

  For this reason, when the second metal separator 18 contacts the insulator 102b in a desired posture, the inlet side backing portion 120a and the line-shaped convex portion 52ag are reliably in contact with each other as shown in FIG. . Similarly, the outlet side backing portion 120b and the line-shaped convex portion 52bg are reliably in contact with each other.

  Here, the second metal separator 18 may come into contact with the insulator 102b in a state where the second metal separator 18 is rotated (inverted) 180 ° from a normal posture. In that case, the line-shaped convex part 52ag and the line-shaped convex part 52bg of the 2nd metal separator 18, and the exit side backing part 120b and the inlet side backing part 120a of the insulator 102b do not mutually overlap in the lamination direction. This is because, as shown in FIG. 8, the line-shaped convex portions 52ag and the line-shaped convex portions 52bg are configured to be asymmetric with respect to each other.

  Therefore, the outlet side backing portion 120b and the inlet side backing portion 120a of the insulator 102b abut on the embossed 52ae and the embossed 52be that are higher than the line-shaped convex portion 52ag and the line-shaped convex portion 52bg.

  As a result, rattling or the like occurs at the contact portion between the insulator 102b and the second metal separator 18, and it is easily understood that the assembly is incorrect. For this reason, in this embodiment, it is possible to easily and reliably prevent erroneous assembly of the power generation unit 12 with a simple configuration.

  In the present embodiment, a so-called thinning cooling structure is adopted in which no cooling medium flow path is provided between the first electrolyte membrane / electrode structure 16a and the second electrolyte membrane / electrode structure 16b. However, the present invention is not limited to this. For example, the present invention can be applied to each cell cooling structure in which a cooling medium flow path is provided for each electrolyte membrane / electrode structure.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Electric power generation unit 13 ... Laminated body 14, 18, 20 ... Metal separator 16a, 16b ... Electrolyte membrane electrode structure 22a ... Oxidant gas inlet communication hole 22b ... Oxidant gas outlet communication hole 24a ... Fuel Gas inlet communication hole 24b ... Fuel gas outlet communication hole 25a ... Cooling medium inlet communication hole 25b ... Cooling medium outlet communication hole 26, 50 ... Oxidant gas flow path 28a, 52a, 84a, 86a, 88a, 90a ... Inlet buffer section 28b , 52b, 84b, 86b, 88b, 90b... Outlet buffer portions 28ae, 28be, 52ae, 52be... Embossed 28ag, 28bg, 52ag, 52bg. , 70, 72 ... sealing member 74 ... solid polymer electrolyte membrane 76 ... cathode electrode 78 ... anode electrode 0,82 ... resin frame member 100a, 100b ... terminal plate 102a, 102b ... insulator 104a, 104b ... end plate 120 ... concave and convex portion 120a ... inlet back receiving portion 120b ... outlet back receiving portion

Claims (3)

A fuel cell in which an electrolyte membrane and electrode structure each provided with an electrode and a separator are laminated on both sides of the electrolyte membrane, and a plurality of the fuel cells are laminated. A reaction gas flow path for supplying a reaction gas that is at least a fuel gas or an oxidant gas, and a plurality of embosses having a height H, and communicates with an inlet side of the reaction gas flow path outside the power generation region. And an outlet buffer section that includes a plurality of embosses having a height H and communicates with the outlet side of the reaction gas channel outside the power generation region and distributes the reaction gas evenly. A fuel cell stack in which a terminal plate, an insulator, and an end plate are disposed at both ends in the stacking direction of the fuel cell,
The terminal plate has a smaller plane size than the insulator, and is accommodated in a recess formed in the insulator,
The insulator corresponds to a region where the plurality of embossments in the inlet buffer portion of the separator do not exist at a portion in direct contact with the separator constituting the end portion of the stack of the fuel cell, and the inlet buffer side height inlet side back receiving portion formed only projects S, and corresponds to a region where the plurality of embossing is not present in the outlet buffer, the outlet is formed to protrude by a height S in the outlet buffer side A side backing part is provided, and the inlet side backing part and the outlet side backing part are configured asymmetrically, and a plurality of embosses on the inlet side backing part and the outlet buffer part side are provided. At least one of them is configured point-symmetrically, at least one of the plurality of embosses on the outlet side backing portion and the inlet buffer portion side is configured point-symmetrically, and S <H Fuel cell stack and satisfies the engagement. 2. The fuel cell stack according to claim 1, wherein the separator has a reaction gas inlet communication hole and a reaction gas outlet communication hole through which the reaction gas flows in the stacking direction.
The inlet buffer section connected to the reaction gas flow path and the reaction gas inlet communication hole, and the outlet buffer section connected to the reaction gas flow path and the reaction gas outlet communication hole are each height. It has a line-shaped convex part of T ,
The fuel cell stack, wherein the line-shaped convex portion of the inlet buffer portion and the line-shaped convex portion of the outlet buffer portion are configured to be asymmetric with respect to each other and satisfy a relationship of S + T = H. The fuel cell stack according to claim 2, wherein the separator is formed with a cooling medium inlet communication hole and a cooling medium outlet communication hole through which the cooling medium flows in the stacking direction,
At least the reaction gas inlet communication hole, the reaction gas outlet communication hole, the cooling medium inlet communication hole, and the cooling medium outlet communication hole are provided at point-symmetric positions.

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