阅读说明：本技术 燃料电池用隔板以及燃料电池堆 (Separator for fuel cell and fuel cell stack ) 是由 小山贤 苫名佑 于 2019-07-12 设计创作，主要内容包括：本公开涉及燃料电池用隔板以及燃料电池堆。燃料电池堆的燃料电池用隔板即第一和第二隔板(30)、(32)具有连通孔凸起部(74)即凸部(80),所述连通孔凸起部(74)即凸部(80)形成为板状,并且形成防止流体泄漏的密封件。连通孔凸起部(74)以从第一和第二隔板(30)、(32)的面(30a)、(32a)突出的方式一体成形,并且在剖视观察时形成为多级梯形形状。(The present disclosure relates to a separator for a fuel cell and a fuel cell stack. The first and second separators (30, 32) for fuel cells of a fuel cell stack have a projection (80) which is a communication hole projection (74), and the projection (80) which is the communication hole projection (74) is formed in a plate shape and forms a seal for preventing fluid leakage. The communication hole protrusions (74) are integrally formed so as to protrude from the surfaces (30a, 32a) of the first and second separators (30, 32), and are formed in a multi-step trapezoidal shape when viewed in cross section.)

1. A separator (30, 32) for a fuel cell having a convex portion (74, 74a, 74b), the convex portion (74, 74a, 74b) being formed in a plate shape and forming a seal for preventing leakage of a fluid, wherein,

the protrusions are formed integrally with the fuel cell separator, protrude from the plate surfaces (30a, 32a) when viewed in cross section, and are formed in a multi-step trapezoidal shape.

2. The separator for a fuel cell according to claim 1,

the protrusion is formed in a two-stage trapezoidal shape when viewed in cross section.

3. The separator for a fuel cell according to claim 1,

the boss has, in a cross-sectional view:

a pair of base-side inclined portions (82) connected to the plate surface and projecting from the plate surface;

a pair of stepped portions (84, 112, 122) connected to the protruding end portions of the pair of base-side inclined portions, respectively, and extending along the inner sides of the pair of base-side inclined portions; and

a protruding end portion (86, 102) that is continuous with an inside end portion of the pair of stepped portions and is separated from the plate surface compared to the pair of stepped portions.

4. The separator for a fuel cell according to claim 3,

the protruding end portion is formed in an arc shape in a state of not being laminated with an object to be sealed, and the protruding end portion is deformed in a flat state in a state of being laminated with the object and receiving a compressive load from the object, when viewed in cross section.

5. The separator for a fuel cell according to claim 3,

the pair of step portions extend in parallel to the surface direction of the plate surface.

6. The separator for a fuel cell according to claim 1,

the separator for a fuel cell has a bleed hole (72) formed through the separator in the thickness direction and through which a refrigerant can flow, and an exhaust hole (70) through which air can flow,

the protrusion is formed around the discharge hole or the exhaust hole.

7. The separator for a fuel cell according to claim 1,

the projection is formed in an annular shape when viewed from a thickness direction of the fuel cell separator.

8. A fuel cell stack (10) is provided with:

the separator (30, 32) for a fuel cell according to any one of claims 1 to 7; and

an electrolyte membrane-electrode assembly (28a),

wherein a plurality of membrane electrode assemblies are alternately stacked on a joint separator (33) composed of a plurality of the fuel cell separators.

Technical Field

The present disclosure relates to a separator for a fuel cell and a fuel cell.

Background

The fuel cell stack is configured by stacking a plurality of power generation cells. The power generation unit cell includes an electrolyte membrane-electrode assembly (MEA) in which an anode electrode, a solid polymer electrolyte membrane, and a cathode electrode are laminated, and a pair of fuel cell separators as bipolar plates sandwiching the MEA.

For example, a pair of plates (separators for fuel cells) applied to a power generating cell is disclosed in U.S. patent No. 6605380. A projection projecting from the surface of the separator is formed on one side of the fuel cell separator. For example, the projection surrounds the outer periphery of the flow path through which the reactant gas flows, and forms a seal between the projection and the other fuel cell separator to prevent leakage of the reactant gas (fluid).

Disclosure of Invention

Problems to be solved by the invention

However, the fuel cell separator can form the plate itself into a concave-convex shape, and the convex portion can form the convex portion. When the projecting end side receives a compressive load in a sealed state, the base portion connected to the plate elastically expands in the width direction to disperse the compressive load. However, when the base portion of the boss is hard (strong restraining force (japanese) acts) due to the shape of the portion where the boss is provided, etc., the base portion cannot be elastically expanded, and may be bent (buckled) at the middle of the portion sealed in the protruding end portion (tip end portion).

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell separator and a fuel cell stack having a protrusion portion that forms a good seal with a simple structure.

Means for solving the problems

In order to achieve the above object, one aspect of the present invention relates to a separator for a fuel cell, which has a projection portion formed in a plate shape and forming a seal member for preventing fluid leakage, wherein the projection portion is formed integrally with the separator for a fuel cell, protrudes from a plate surface when viewed in cross section, and is formed in a multi-step trapezoidal shape.

In order to achieve the above object, a fuel cell stack according to an aspect of the present invention includes the above fuel cell separator and a membrane electrode assembly, wherein a plurality of membrane electrode assemblies and a plurality of joint separators formed of a plurality of the fuel cell separators are alternately stacked.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the fuel cell separator and the fuel cell stack have a simple structure in which the boss portion is integrally formed so as to protrude from the plate surface, and the boss portion is formed in a multi-step trapezoidal shape in a cross-sectional view, and a seal for preventing fluid leakage can be formed satisfactorily. That is, when the projection receives a compressive load in the stacked state of the fuel cell separator, the stepped portion of the multistage trapezoidal shape is actively deformed (flexed) compared to the portion of the seal that contacts the object. Therefore, even when a strong restraining force acts on the base portion of the projection portion close to the plate surface, the seal can be performed while suppressing the occurrence of intermediate bending at the contact portion. Thus, the projection can more reliably prevent the fluid from leaking from the sealed portion with the object, and the fluid can stably flow.

The above objects, features and advantages can be easily understood by describing the following embodiments with reference to the accompanying drawings.

Drawings

Fig. 1 is a perspective view showing the overall structure of a fuel cell stack to which a fuel cell separator according to an embodiment of the present invention is applied.

Fig. 2 is an exploded perspective view showing a power generation unit cell of the fuel cell stack.

Fig. 3 is a partial plan view showing a structure in the vicinity of the refrigerant discharge communication hole to which the separator is joined.

Fig. 4A is a sectional view taken along line IV-IV of the first separator of fig. 3.

Fig. 4B is a graph showing a change in shape in the stacked state of the multi-stage convex portion according to the present embodiment and a change in shape in the stacked state of the single-stage convex portion according to the comparative example.

Fig. 5A is a partial cross-sectional view showing the first and second separators and the resin frame member in the vicinity of the refrigerant discharge communication hole before lamination.

Fig. 5B is a partial sectional view showing the first and second separators and the resin frame member in the vicinity of the refrigerant discharge communication hole in a stacked state.

Fig. 6A is a cross-sectional view of a convex portion according to a first modification.

Fig. 6B is a cross-sectional view of a convex portion according to a second modification.

Fig. 6C is a cross-sectional view of a convex portion according to a third modification.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1, a fuel cell stack 10 according to an embodiment of the present invention includes a stack 14 in which a plurality of power generation cells 12 constituting a unit fuel cell are stacked in a horizontal direction (arrow a direction) or a gravitational direction (arrow C direction) in the stack 14. The fuel cell stack 10 is mounted on, for example, a fuel cell vehicle (fuel cell vehicle) not shown.

At one end of the stacked body 14 in the stacking direction (the direction of arrow a), a terminal plate 16a, an insulator 18a, and an end plate 20a are arranged in this order toward the outside. At the other end of the stacked body 14 in the stacking direction, a terminal plate 16b, an insulator 18b, and an end plate 20b are arranged in this order toward the outside.

The terminal plates 16a and 16b are metal plate members for extracting electric power from the power generation cells 12, and have terminal portions 68a and 68b extending outward in the stacking direction at the center thereof. The insulators 18a and 18b are made of an insulating material such as Polycarbonate (PC) or phenol resin.

The end plates 20a, 20b have a horizontally long (or vertically long) rectangular shape, and a connecting rod 24 is disposed between each side. The connecting rods 24 are screwed to the inner surfaces of the end plates 20a, 20b, and apply a fastening load in the stacking direction (the direction of arrow a) to the plurality of stacked power generation cells 12. The fuel cell stack 10 may be configured to include a casing having end plates 20a and 20b as end plates, and to accommodate the stack 14 in the casing.

As shown in fig. 2, the power generation cell 12 includes: a resin framed MEA 28, a first metal separator 30 (hereinafter simply referred to as a first separator 30) disposed on one surface side of the resin framed MEA 28, and a second metal separator 32 (hereinafter simply referred to as a second separator 32) disposed on the other surface side of the resin framed MEA 28. The first and second separators 30, 32 are formed in a plate shape, and correspond to the fuel cell separator of the present invention.

The first and second separators 30, 32 are formed by press-forming a cross section of a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a thin metal plate having a surface treatment for corrosion prevention applied to a metal surface thereof into a corrugated shape, for example. The first and second separators 30, 32 are joined to each other at their outer peripheries by welding, brazing, caulking, or the like to constitute an integral joined separator 33.

At one end (an end on the side of the arrow B1) in the horizontal direction, which is the longitudinal direction of the power generation cell 12, the oxygen-containing gas supply passage 34a, the refrigerant supply passage 36a, and the fuel gas discharge passage 38B are provided so as to communicate with each other along the stacking direction (the direction of the arrow a). The oxygen-containing gas supply passage 34a, the refrigerant supply passage 36a, and the fuel gas discharge passage 38b are arranged in the vertical direction (the direction indicated by the arrow C). The oxygen-containing gas supply passage 34a supplies an oxygen-containing gas, for example, an oxygen-containing gas. The refrigerant supply communication hole 36a supplies refrigerant, for example, water. The fuel gas discharge passage 38b discharges a fuel gas such as a hydrogen-containing gas.

At the other end in the longitudinal direction of the power generation cell 12 (the other end in the direction of arrow B2), a fuel gas supply passage 38a, a refrigerant discharge passage 36B, and an oxygen-containing gas discharge passage 34B are provided so as to communicate with each other in the stacking direction. The fuel gas supply passage 38a, the refrigerant discharge passage 36b, and the oxygen-containing gas discharge passage 34b are aligned in the vertical direction. The fuel gas supply passage 38a supplies the fuel gas. The refrigerant discharge communication hole 36b discharges the refrigerant. The oxygen-containing gas discharge passage 34b discharges the oxygen-containing gas. The arrangement of the oxygen-containing gas supply passage 34a, the oxygen-containing gas discharge passage 34b, the fuel gas supply passage 38a, the fuel gas discharge passage 38b, the refrigerant supply passage 36a, and the refrigerant discharge passage 36b is not limited to the present embodiment, and may be set as appropriate according to the required specifications.

The resin framed MEA 28 includes a membrane electrode assembly 28a (hereinafter referred to as "MEA 28 a") and a resin frame member 46 joined to and surrounding the outer peripheral portion of the MEA 28 a. As the resin frame member 46, a frame-shaped film member can be used. The MEA 28a includes an electrolyte membrane 40, an anode electrode 42 provided on one surface of the electrolyte membrane 40, and a cathode electrode 44 provided on the other surface of the electrolyte membrane 40. In addition, the MEA 28a may protrude the electrolyte membrane 40 outward without using the resin frame member 46. Further, frame-shaped resin films may be provided on both sides of the electrolyte membrane 40 protruding outward.

As the electrolyte membrane 40, for example, a solid polymer electrolyte membrane (cation exchange membrane) which is a thin membrane of perfluorosulfonic acid containing moisture is applied. In addition, the electrolyte membrane 40 may use a HC (hydrocarbon) electrolyte in addition to a fluorine electrolyte.

The inner peripheral end surface of the resin frame member 46 is close to, overlaps, or abuts the outer peripheral end surface of the electrolyte membrane 40. At the end of the resin frame member 46 on the side of arrow B1, the oxygen-containing gas supply passage 34a, the refrigerant supply passage 36a, and the fuel gas discharge passage 38B are provided. At the end of the resin frame member 46 in the direction of arrow B2, a fuel gas supply passage 38a, a refrigerant discharge passage 36B, and an oxygen-containing gas discharge passage 34B are provided.

The resin frame member 46 is made of, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), silicone resin, fluorine resin, or m-PPE (modified polyphenylene ether resin), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), or modified polyolefin.

As shown in fig. 3, an oxidizing gas passage 48 through which an oxidizing gas flows is provided in a surface 30a of the first separator 30 that faces the cathode electrode 44 of the resin frame-attached MEA 28 (in fig. 2, the flow direction of the oxidizing gas is shown in the cathode electrode 44 of the MEA 28a for convenience). The oxidizing gas flow field 48 is formed of linear flow field grooves 48B (or wavy flow field grooves) formed between a plurality of protrusions 48a of the first separator 30 extending in the direction indicated by the arrow B (horizontal direction).

The oxygen-containing gas flow field 48 is fluidly connected to the oxygen-containing gas supply passage 34a and the oxygen-containing gas discharge passage 34 b. An inlet buffer 50A having a plurality of embossed portions is provided on the surface 30A of the first separator 30 between the oxygen-containing gas supply passage 34a and the oxygen-containing gas flow field 48. Further, an outlet buffer 50B having a plurality of embossed portions is provided on the surface 30a of the first separator 30 between the oxygen-containing gas discharge passage 34B and the oxygen-containing gas flow field 48.

As shown in fig. 3, a first seal line 51 (seal member protrusion) protruding toward the MEA 28 with a resin frame is press-formed on the surface 30a of the first separator 30. The first seal line 51 includes an inner protrusion 51a surrounding the oxidizing gas channel 48, the inlet buffer 50A, and the outlet buffer 50B; and an outer protrusion 51b extending along the outer periphery of the first separator 30 on the outer side of the inner protrusion 51 a.

The first seal line 51 has a plurality of communication hole protrusions 52 that surround the oxygen-containing gas supply communication hole 34a, the oxygen-containing gas discharge communication hole 34b, the fuel gas supply communication hole 38a, the fuel gas discharge communication hole 38b, the refrigerant supply communication hole 36a, and the refrigerant discharge communication hole 36b, respectively. A plurality of bridge portions 53 are provided inside and outside the communication hole protrusions 52 that surround the oxygen-containing gas supply communication hole 34a and the oxygen-containing gas discharge communication hole 34 b. Each bridge portion 53 is formed by press molding to protrude toward the resin framed MEA 28. The bridge portion 53 has: a channel (not shown) that communicates with the oxygen-containing gas supply passage 34a and the oxygen-containing gas flow field 48 and supplies the oxygen-containing gas introduced from the oxygen-containing gas supply passage 34a to the oxygen-containing gas flow field 48; and a channel (not shown) that communicates with the oxygen-containing gas flow field 48 and the oxygen-containing gas discharge passage 34b and through which the oxygen-containing gas discharged from the oxygen-containing gas flow field 48 flows out to the oxygen-containing gas discharge passage 34 b. The inner boss 51a, the outer boss 51b, and the communication hole boss 52 protrude from the plate surface (surface 30a) of the first separator 30, and are formed in a single-step trapezoidal shape when viewed in cross section (when viewed in cross section along the thickness direction of the first separator 30).

Returning to fig. 2, the second separator 32 includes a fuel gas flow field 58 through which the fuel gas flows on a surface 32a thereof facing the anode electrode 42 of the resin framed MEA 28. The fuel gas flow field 58 is constituted by a linear flow field groove 58B (or a wavy flow field groove) formed between a plurality of protrusions 58a of the second separator 32 extending in the direction indicated by the arrow B (horizontal direction). The fuel gas flow field 58 is fluidly connectable to the fuel gas supply passage 38a and the fuel gas discharge passage 38 b.

An inlet buffer 60A having a plurality of embossed portions is provided on the surface 32a of the second separator 32 between the fuel gas supply passage 38a and the fuel gas flow field 58. Further, an outlet buffer 60B having a plurality of embossed portions is provided on the surface 32a of the second separator 32 between the fuel gas discharge passage 38B and the fuel gas flow field 58.

A second seal line 61 (seal projection) that projects toward the resin framed MEA 28 is press-formed on the surface 32a of the second separator 32. The second seal line 61 includes an inner protrusion 61a that surrounds the fuel gas flow path 58, the inlet buffer 60A, and the outlet buffer 60B; and an outer protrusion 61b extending along the outer periphery of the second separator 32 on the outer side of the inner protrusion 61 a.

The second seal line 61 includes a plurality of communication hole protrusions 62 that surround the oxygen-containing gas supply communication hole 34a, the oxygen-containing gas discharge communication hole 34b, the fuel gas supply communication hole 38a, the fuel gas discharge communication hole 38b, the refrigerant supply communication hole 36a, and the refrigerant discharge communication hole 36b, respectively. Inside and outside the communication hole protrusions 62 that surround the fuel gas supply communication hole 38a and the fuel gas discharge communication hole 38b, bridges 63 that communicate with the fuel gas supply communication hole 38a and the fuel gas discharge communication hole 38b are provided. Each bridge portion 63 is formed by press molding to protrude toward the resin framed MEA 28. The bridge 63 has: a channel (not shown) that communicates with the fuel gas supply passage 38a and the fuel gas flow field 58 and supplies the fuel gas introduced from the fuel gas supply passage 38a to the fuel gas flow field 58; and a channel (not shown) that communicates with the fuel gas flow field 58 and the fuel gas discharge passage 38b and flows the fuel gas discharged from the fuel gas flow field 58 into the fuel gas discharge passage 38 b. The inner boss portion 61a, the outer boss portion 61b, and the communication hole boss portion 62 protrude from the plate surface (surface 32a) of the second separator 32, and are formed in a single-step trapezoidal shape in cross-sectional view.

A refrigerant flow field 66 that is in fluid communication with the refrigerant supply passage 36a and the refrigerant discharge passage 36b is formed between the surface 30b of the first separator 30 and the surface 32b of the second separator 32 plate joined to each other. The coolant flow field 66 is formed by overlapping the shape of the back surface of the other surface of the first separator 30 on which the oxidant gas flow field 48 is formed and the shape of the back surface of the other surface of the second separator 32 on which the fuel gas flow field 58 is formed.

The gas discharge communication hole 70 and the refrigerant discharge communication hole 72, which are substantially circular in plan view, penetrate the first separator plate 30, the second separator plate 32, and the resin framed MEA 28 (resin frame member 46) in the stacking direction. The discharge communication hole 70 is a hole for discharging air in the refrigerant, is provided at an upper corner portion (above the uppermost portion of the inner protrusions 51a, 61 a) on the side of the power generation cell 12 in the arrow B1 direction, and has a smaller opening area than the reactant gas communication hole and the refrigerant communication hole. The refrigerant discharge communication hole 72 is provided at a lower corner portion (below the lowermost portion of the inner protrusions 51a, 61 a) on one end side (the arrow B1 side) in the horizontal direction of the power generation cell 12, and has a smaller opening area than the reactant gas communication hole and the refrigerant communication hole. The positions and shapes of the discharge communication hole 70 and the refrigerant discharge communication hole 72 are not particularly limited. The resin framed MEA 28 and the first and second separators 30, 32 may be provided with other bleed holes (a cathode bleed hole through which water or the like leaking from the path of the oxidizing gas flows, an anode bleed hole through which water or the like leaking from the path of the fuel gas flows, and the like).

Then, communication hole bosses 74 that surround the exhaust communication hole 70 and the refrigerant drain communication hole 72 are press-formed (integrally formed) on the surfaces 30a, 32a of the first and second separators 30, 32 that face the resin framed MEA 28, respectively. Hereinafter, the communication hole projection provided in the first separator 30 is referred to as a communication hole projection 74a, and the communication hole projection provided in the second separator 32 is referred to as a communication hole projection 74 b.

The communication hole protrusions 74 protrude from the plate surfaces ( surfaces 30a, 32a) of the first and second separators 30, 32, and are formed in a circular shape in plan view. The communication hole projection 74 surrounds the discharge communication hole 70 and the refrigerant discharge communication hole 72, respectively, but basically has the same configuration. Hereinafter, the refrigerant discharge communication hole 72 provided in the first separator 30 and the communication hole projection 74 surrounding the periphery thereof will be representatively described with reference to fig. 3.

The refrigerant discharge communication hole 72 communicates with the refrigerant flow field 66 via a connection flow field 76. The connection flow path 76 is a space formed by overlapping the rear side concave portions of the first and second seal lines 51, 61, which form the bulging shape, and communicates the refrigerant discharge communication hole 72 with the internal space (rear side concave portion) of the inner bosses 51a, 61 a.

Specifically, the first and second seal lines 51 and 61 include coupling projections 78a and 78b, and the coupling projections 78a and 78b include the coupling flow path 76 therein. Only one of the coupling bosses 78a and 78b may be provided. The coupling bosses 78a, 78b are formed in a single-step trapezoidal shape in cross-sectional view, and one end thereof is connected to the lowermost portions of the inner bosses 51a, 61a, and the other end thereof is connected to the outer peripheral side wall 74s1 of the communication hole boss 74.

Further, passages 79a, 79b are provided in the first and second separators 30, 32 from the inner peripheral side wall 74s2 of the communication hole projecting portion 74 toward the refrigerant discharge communication hole 72, respectively. That is, the refrigerant flow path 66 and the refrigerant discharge communication hole 72 communicate with each other via the internal spaces of the inner bosses 51a and 61a, the internal spaces of the coupling bosses 78a and 78b, the internal spaces of the communication hole bosses 74a and 74b, and the internal spaces of the passages 79a and 79 b.

The communication hole projection 74 according to the present embodiment is annular in plan view, and is formed as a multi-step trapezoidal projection 80 projecting from the plate surfaces ( surfaces 30a, 32a) of the first and second separators 30, 32 in cross-sectional view as shown in fig. 4A. For example, the protruding height of the convex portion 80 is set to be in the range of 10% to 35% with respect to the width dimension of the convex portion 80. The planar shape of the communication hole projection 74 is not limited to an annular shape.

Specifically, the projection 80 includes: in the non-stacked state of the power generating cells 12, a pair of basal inclined portions 82 continuous with the plate surface, a pair of stepped portions 84 continuous with the upper ends of the basal inclined portions 82 and substantially parallel to the plate surface, and projecting end portions 86 continuous with the insides of the stepped portions 84 and projecting in the direction away from the plate surface. That is, when the plate surface is used as a reference, the convex portion 80 has a two-step trapezoidal shape formed by the following ridges: the pair of steps 84 are first-stage protuberances, and the protruding end portions 86 are second-stage protuberances.

The pair of base-side inclined portions 82 are inclined at the first inclination angle α with respect to the plate surface, and support the pair of stepped portions 84 at a predetermined height. More specifically, in the non-stacked state of the power generating cells 12, the ratio of the height of the pair of step portions 84 to the overall protrusion height of the convex portions 80 protruding from the plate surface is set to be in the range of 20% to 85%. The base-side inclined portion 82 is smoothly connected to the plate surface via a rounded (japanese: R-shaped) plate-side connecting portion 88 having a first curvature.

The pair of steps 84 are substantially parallel to the plate surface as described above, and extend in a width shorter than the width of the protruding end portion 86. The stepped portion 84 is smoothly coupled to the base-side inclined portion 82 via a base-side coupling portion 90 having a rounded shape with the second curvature. The second curvature is set to be larger than the first curvature. The pair of steps 84 are designed to have the same width. The root-side coupling portion 90 may be formed thinner than the other portions of the convex portion 80.

The protruding end portion 86 is formed in an arc shape in cross-sectional view, bridging the ends of the pair of step portions 84. The widthwise central portion 86a of the protruding end portion 86 is located at the highest position of the convex portion 80 in the non-stacked state of the power generating cells 12. The widthwise outer side of the projecting end portion 86 is inclined at the second inclination angle β with respect to the stepped portion 84. The second inclination angle β is set to an angle (α > β) smaller than the first inclination angle α. The protruding end portion 86 is smoothly coupled to the stepped portion 84 via an angular protruding end portion side coupling portion 92 having a third curvature. The third curvature is set smaller than the second curvature.

A resin material 94 such as polyester fiber is fixed to the surface of the projecting end portion 86 in the projecting direction by printing, coating, or the like. The resin material 94 is provided in a range (about 50% to 90%) of the protruding end portion-side coupling portion 92 on the protruding end portion 86, and is bent and extended in the width direction of the protruding end portion 86. Further, the resin material 94 may be provided on the object (resin frame member 46) sealed by the communication hole protrusion 74. The resin material 94 may be omitted, or the projecting end portion 86 may directly abut against the resin frame member 46.

As shown in fig. 5A, in a state where the first and second separators 30, 32 are each separated from the resin frame member 46 (non-stacked state), the projection 80 (communication hole projection 74) has the above-described two-step trapezoidal shape. As shown in fig. 5B, when the power generating cell 12 is manufactured, the first and second separators 30, 32 are stacked on the resin framed MEA 28.

In this laminated state, the convex portions 80 located at the outer peripheral portions of the first and second separators 30, 32 form seals that contact the resin frame member 46 to prevent fluid leakage. In the stacked state, the convex portion 80 applies a compressive load in the stacking direction of the first and second separators 30, 32, and deforms from the shape in the non-stacked state. Specifically, the projecting end portion 86 of the projecting portion 80 formed in the two-step trapezoidal shape, which projects most from the plate surface and comes into direct contact with the facing surface of the resin frame member 46, receives the compression load. Thereby, the projecting end portion 86 is crushed from the arc shape to be flat, and both end portions of the projecting end portion 86 are expanded in the width direction.

As a result, the projecting end portion side coupling portions 92 of the pair of stepped portions 84 coupled to the projecting end portion 86 elastically deform while receiving the compression load from the projecting end portion 86. That is, the pair of stepped portions 84 maintain the height of the base side coupling portion 90 coupled to the pair of base side inclined portions 82 while the height of the protruding end side coupling portion 92 coupled to the protruding end portion 86 is reduced (moved toward the plate surface side) by the compression load. Therefore, the pair of step portions 84 and the protruding end portion 86 are deformed to have the concave portion 96. In particular, the communication hole boss 74 surrounding the refrigerant discharge communication hole 72 is formed in a small-diameter circular shape (see also fig. 3), and the restraining force of the base-side inclined portion 82 is increased (the base-side inclined portion 82 is less likely to deform). This actively promotes the deformation of the stepped portion 84, and the protruding end portion 86 is easily crushed into a flat shape, so that the protruding end portion 86 can be brought into good ground contact with the resin frame member 46.

The fuel cell separator and the fuel cell stack 10 according to the present embodiment are basically configured as described above, and the operation thereof will be described below.

As shown in fig. 1, in the fuel cell stack 10, the oxygen-containing gas is supplied to the oxygen-containing gas supply passage 34a of the end plate 20a, the fuel gas is supplied to the fuel gas supply passage 38a of the end plate 20a, and the refrigerant is supplied to the refrigerant supply passage 36a of the end plate 20 a.

As shown in fig. 2, the oxygen-containing gas is introduced from the oxygen-containing gas supply passage 34a into the oxygen-containing gas flow field 48 of the first separator 30 via the bridge portion 53 (see fig. 3). The oxidizing gas then moves along the oxidizing gas channel 48 in the direction indicated by the arrow B and is supplied to the cathode electrode 44 of the MEA 28 a.

On the other hand, the fuel gas is introduced from the fuel gas supply passage 38a to the fuel gas flow field 58 of the second separator 32 via the bridge portion 63. The fuel gas then moves in the direction indicated by the arrow B along the fuel gas flow field 58 and is supplied to the anode electrode 42 of the MEA 28 a.

Therefore, each MEA 28a generates electricity by an electrochemical reaction between the oxidant gas supplied to the cathode electrode 44 and the fuel gas supplied to the anode electrode 42.

The oxygen-containing gas consumed by being supplied to the cathode electrode 44 flows from the oxygen-containing gas flow field 48 to the oxygen-containing gas discharge passage 34b through the bridge portion 53, and is discharged in the direction indicated by the arrow a along the oxygen-containing gas discharge passage 34 b. Similarly, the fuel gas supplied to and consumed by the anode electrode 42 flows from the fuel gas flow field 58 through the bridge portion 63 into the fuel gas discharge passage 38b, and is discharged along the fuel gas discharge passage 38b in the direction indicated by the arrow a.

The refrigerant supplied to the refrigerant supply passage 36a is introduced into the refrigerant flow path 66 formed between the first separator 30 and the second separator 32, and then flows in the direction indicated by the arrow B. The coolant cools MEA 28a, and is then discharged from coolant discharge passage 36 b.

Here, as shown in fig. 2 and 3, the discharge communication hole 70 communicates with the refrigerant flow path 66 via the internal spaces of the inner bosses 51a and 61a, the internal spaces of the coupling bosses 78a and 78b, the internal spaces of the communication hole bosses 74a and 74b, and the internal spaces of the passages 79a and 79 b. Due to this communication, the air contained in the refrigerant can appropriately flow into the discharge communication holes 70, and the air can flow in the stacking direction of the stacked body 14. The refrigerant discharge communication hole 72 communicates with the refrigerant flow field 66 via the internal spaces of the inner bosses 51a, 61a, the internal spaces of the coupling bosses 78a, 78b, the internal spaces of the communication hole bosses 74a, 74b, and the internal spaces of the passages 79a, 79 b. Due to this communication, the refrigerant can appropriately flow into the refrigerant discharge communication hole 72, and the refrigerant can flow in the stacking direction of the stacked body 14.

As shown in fig. 3, 5A, and 5B, seals are formed around the discharge communication hole 70 and the refrigerant discharge communication hole 72 by the communication hole protrusions 74a and 74B of the first and second separators 30 and 32. In a cross-sectional view, the convex portion 80 deforms from an arc shape to a flat shape as the protruding end portion 86 applies a compressive load to the stacked body 14. This eliminates a local decrease or increase in the seal surface pressure, and makes it possible to uniformize the surface pressure distribution in the seal width direction at the projecting end portion 86, thereby improving the sealing performance.

In particular, the discharge passage 70 and the refrigerant drain passage 72 have opening areas smaller than the flow cross-sectional areas of the fuel gas, the oxygen-containing gas, and the refrigerant, and are formed in a circular shape having a short circumference. Therefore, the base portion (base-side inclined portion 82) of the convex portion 80 is stronger in restraining force than other convex portions (inner convex portions 51a, 61a, and the like) formed in a single-step trapezoidal shape. The change in shape of the protruding end portion when the restraining force of the base portion is strong will be described with reference to fig. 4B. Fig. 4B shows a shape change in the case where the communicating hole projecting portion of the comparative example is formed in a single-stage trapezoidal shape and a strong restraining force is applied. In this case, even if a compressive load is applied, the base portion is not displaced by the restraining force of the base portion, and the projecting end portion may be bent at first (the central portion serving as the seal portion is recessed), which tends to reduce the sealing performance.

In contrast, the projection 80 (the communication hole protrusions 74a and 74b) according to the present embodiment can actively promote the deformation of the stepped portion 84 when a compressive load is applied even if the base portion is not displaced by the restraining force, and the protruding end portion 86 is easily crushed into a flat shape. This enables the protruding end portion 86 to be in good ground contact with the resin frame member 46 (see also fig. 5B). As a result, the refrigerant flowing through the refrigerant discharge communication hole 72 can be reliably blocked from leaking to the outside through the seals of the communication hole protrusions 74a, 74 b.

The shape of the convex portion 80 is not limited to the above-described embodiment, and various configurations can be adopted. For example, as in the first modification shown in fig. 6A, the protruding end portion 102 of the protruding portion 100 may have a pair of protruding end side inclined portions 102a that are inclined and protrude from the pair of step portions 84, respectively, and an end surface portion 102b that bridges the pair of protruding end side inclined portions 102a, and the end surface portion 102b may be formed in a flat shape. The resin material 94 is fixed to the surface of the end surface portion 102 b. Even with such a configuration, when the convex portion 100 receives a compressive load, the stepped portion 84 deforms in the same manner as in the above-described embodiment, and thus the sealed state of the end surface portion 102b can be maintained satisfactorily.

For example, as in the second modification shown in fig. 6B, the convex portion 110 may be formed in a trapezoidal shape having two step portions 112 (a lower step portion 112a and an upper step portion 112B), and the upper step portion 112B may have a protruding end portion 86 protruding in a hemispherical shape. In other words, if the convex portions 80, 100, and 110 are formed in a trapezoidal shape having two or more steps, the same effects as those of the above-described embodiment can be obtained.

For example, as in a third modification shown in fig. 6C, the pair of stepped portions 122 of the convex portion 120 may be inclined obliquely upward from one end portion (the proximal-side connecting portion 90) toward the other end portion (the protruding-end-side connecting portion 92). That is, the convex portion 120 may have only an appropriate curved portion 124 (the base-side coupling portion 90 and the protrusion-end-side coupling portion 92) so that the concave portion 96 (see fig. 5B) is formed in the stepped portion 122. In this case, the step portion 122 is deformed, whereby the deformation (intermediate bending) of the widthwise central portion can be suppressed, and the same effect as that of the above-described embodiment can be obtained.

The fuel cell separators (first and second separators 30, 32) and the fuel cell stack 10 according to the present embodiment achieve the following effects.

The protrusions (communication hole protrusions 74) of the fuel cell separators (first and second separators 30, 32) are formed integrally with the first and second separators 30, 32, protrude from the plate surface in a cross-sectional view, and are formed in a simple structure having a multi-step trapezoidal shape, whereby a seal can be formed satisfactorily. That is, when the communication hole protrusions 74 receive a compressive load in accordance with the lamination of the fuel cells, the stepped portions are actively deformed (flexed) in comparison with the portions of the seal that contact the object (resin frame member 46). Therefore, even when a strong restraining force acts on the base portion close to the plate surface, the communication hole projection 74 can seal the contact portion while suppressing the occurrence of intermediate bending. This enables the communication hole projection 74 to more reliably prevent the fluid from leaking from the sealed portion with the object, and to stably circulate the fluid.

In addition, the boss portion (communication hole boss portion 74) is formed in a two-step trapezoidal shape in cross-sectional view. The two-step trapezoidal communication hole projection 74 can be easily processed by press forming, and the manufacturing cost can be reduced.

In addition, the boss (communication hole boss 74) has, in cross-sectional view: a pair of basal-side inclined portions 82 connected to and projecting from the plate surface; a pair of stepped portions 84 connected to the projecting end portions (basal side coupling portions 90) of the pair of basal side inclined portions 82, respectively, and extending along the insides of the pair of basal side inclined portions 82; and a protruding end portion 86 that is continuous with an inner end portion (protruding end portion side coupling portion 92) of the pair of step portions 84 and is separated from the plate surface in comparison with the pair of step portions 84. Thus, the communication hole protrusion 74 can actively promote deformation of the step portion 84 when a compressive load is applied, and the protruding end portion 86 can be easily crushed flat, so that the protruding end portion 86 can be in good ground contact with the resin frame member 46.

In a cross-sectional view, the protruding end portion 86 is formed in an arc shape in a state where it is not laminated with the object to be sealed (the resin frame member 46), and is deformed into a flat shape in a state where it is laminated with the resin frame member 46 and receives a compressive load from the resin frame member 46. Thus, when receiving the compressive load, the projecting end portion 86 is uniformly expanded in the width direction and deformed into a flat shape, and the surface pressure of the seal portion can be made more uniform.

The pair of stepped portions 84 extend parallel to the surface direction of the plate surface. Thus, the pair of stepped portions 84 can smoothly move toward the plate surface side when receiving the compressive load.

Here, it is preferable that the fuel cell separator (the first and second separators 30 and 32) have a discharge hole (the refrigerant discharge communication hole 72) through which the refrigerant can flow and an air discharge hole (the air discharge communication hole 70) through which the air can flow, and a projection (the communication hole projection 74) is formed around the refrigerant discharge communication hole 72 or the air discharge communication hole 70. The discharge communication hole 70 and the refrigerant discharge communication hole 72 are formed to have a small opening area, and the communication hole projection 74 around the discharge communication hole and the refrigerant discharge communication hole is also formed to be small, so that the root side is hardly deformed. Even in this case, by the above-described action of the multi-step trapezoidal shape, the communication hole protrusion 74 can maintain the seal satisfactorily even when a compressive load is applied. As a result, the leakage of the fluid from the discharge communication hole 70 and the refrigerant discharge communication hole 72 can be reliably blocked.

The projection (the communication hole projection 74) may be formed in an annular shape when viewed in the thickness direction of the fuel cell separator. Even in this case, the root side of the communication hole boss 74 is hardly deformed, but the sealing can be maintained satisfactorily even when a compressive load is applied by the action of the multi-step trapezoidal shape.

The fuel cell stack 10 may be configured to include the fuel cell separators (the first and second separators 30, 32) and the membrane electrode assembly 28a, wherein the joint separators 33 formed of the plurality of first and second separators 30, 32 and the plurality of MEAs 28a are alternately stacked. The fuel cell stack 10 has the above-described projecting portions (communication hole projecting portions 74), and thus can satisfactorily form a seal in a stacked state, and reliably block leakage of fluid.

The present invention is not limited to the above-described embodiments, and various modifications can be made in accordance with the gist of the present invention. For example, the bosses (the protrusions 80, 100, 110, 120) are not limited to those provided around the discharge communication hole 70 and the refrigerant drain communication hole 72, and may be applied to other portions of the first and second seal lines 51, 61. That is, the projections 80, 100, 110, 120 having a multi-step trapezoidal shape may be applied to the inner projections 51a, 61a, the outer projections 51b, 61b, the communication hole projections 52, 62, and the like.

For example, the planar shapes of the discharge communication hole 70 and the refrigerant discharge communication hole 72 are not limited to circular shapes, and may be polygonal shapes such as rectangular shapes, square shapes, and hexagonal shapes, or various shapes such as elliptical shapes. Preferably, the polygonal communication hole has a rounded corner. The planar shape of the projection (the projection 80, 100, 110, 120) surrounding the discharge communication hole 70 and the refrigerant discharge communication hole 72 may be a polygonal shape such as a rectangle, a square, or a hexagon, or an ellipse, depending on the planar shape of the communication hole.