CN112242532B - Metal separator for fuel cell, joined separator, and power generation cell - Google Patents

Abstract

The present invention relates to a metal separator for a fuel cell, a joint separator and a power generation cell. In a metal separator for a fuel cell (14) which is stacked with an electrolyte membrane-electrode structure (12a) to form a power generation cell (10) and is used to prevent fluid leakage, the raised seal (45, 47) is provided with: a curved portion (51, 61) including a top portion (50, 60) which is most prominent in the stacking direction in a cross section perpendicular to a sealing line; and a spring portion (side portion 52, 53, 62, 63) which is arranged on both sides of the curved portion (51, 61) and has a soft spring property compared to the curved portion (51, 61).

Description

Metal separator for fuel cell, bonded separator and power generation cell

Technical Field

The present invention relates to a metal separator for a fuel cell having a protrusion seal, a joint separator, and a power generation cell.

Background technique

In the past, the following fuel cell (power generation cell) is known, which comprises: an electrolyte membrane-electrode structure (MEA) formed by configuring an anode electrode on one side of an electrolyte membrane formed by a polymer ion exchange membrane and configuring a cathode electrode on the other side of the electrolyte membrane; and a separator (also called a bipolar plate) configured on both sides of the MEA. Generally, a fuel cell stack is formed by stacking a predetermined number of power generation cells. The fuel cell stack is assembled into a fuel cell vehicle (fuel cell electric vehicle, etc.) as a vehicle-mounted fuel cell stack.

In fuel cells, metal separators are sometimes used as separators. In this case, a sealing member is provided on the metal separator to prevent leakage of oxidant gas, fuel gas, and cooling medium. The sealing member uses elastic rubber seals such as fluorine resin and silicon, which has the problem of high cost.

Therefore, for example, as disclosed in Patent Document 1, a sealing protrusion (hereinafter also referred to as a protrusion seal) is formed on the metal partition instead of the elastic rubber seal. The protrusion seal has a shape that bulges from the flat portion (bottom plate portion) of the metal partition in the thickness direction. Since the protrusion seal is stamped, it has the advantage of low manufacturing cost.

Prior art literature

Patent Literature

Patent Document 1: U.S. Patent Application Publication No. 2006/0054664

Summary of the invention

Problems to be solved by the invention

The protruding portion of the protruding seal abuts against other components (resin frame components, etc.) to form a linear sealing portion to perform a sealing function. However, in conventional protruding seals, the portion where the protruding seal abuts against other components is buckled and concave, and it is found that the sealing function is reduced.

Therefore, an object of the present invention is to provide a metal separator for a fuel cell, a bonded separator, and a power generation cell including a bead seal whose sealing function is unlikely to be reduced by preventing deformation of the sealing surface of the bead seal.

Solutions for solving problems

One aspect of the present invention is a metal separator for a fuel cell, which is stacked with an electrolyte membrane-electrode structure formed by respectively arranging electrodes on both sides of an electrolyte membrane to form a power generation cell, and a raised seal for preventing leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium protrudes in the stacking direction of the electrolyte membrane-electrode structure. In the metal separator for a fuel cell, there are flat portions on both sides of the raised seal and a bottom plate portion perpendicular to the stacking direction, and the raised seal, in an initial state when not compressed in the stacking direction, has: a bent portion protruding separately in the stacking direction; a folded portion arranged on both sides of the bent portion; and a spring portion extending obliquely from the folded portion toward the bottom plate portion.

Another aspect of the present invention is a joined separator, which is formed by stacking a plurality of the above-mentioned metal separators for fuel cells, wherein adjacent metal separators for fuel cells are joined in such a manner that the tops of the respective protruding seals protrude in opposite directions in the stacking direction.

Another aspect of the present invention is a power generation cell, comprising: an electrolyte membrane-electrode structure formed by respectively arranging electrodes on both sides of an electrolyte membrane; and metal separators respectively arranged on both sides of the electrolyte membrane-electrode structure, wherein on the metal separators, raised seals for preventing leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium are protrudingly formed in the stacking direction of the electrolyte membrane-electrode structure and the metal separators, and in the power generation cell, there are flat portions on both sides of the raised seals and a bottom plate portion perpendicular to the stacking direction, and the raised seals in an initial state where they are not compressed in the stacking direction comprise: a bent portion protruding separately in the stacking direction; a folded portion arranged on both sides of the bent portion; and a spring portion extending obliquely from the folded portion toward the bottom plate portion.

Effects of the Invention

According to the metal separator for a fuel cell, the bonded separator, and the power generating cell of the above aspects, deformation of the sealing surface of the protruding seal can be prevented, thereby preventing a reduction in the sealing function.

The above-mentioned objects, features and advantages can be easily understood from the following description of the embodiments described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a power generating cell according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the power generating cell of FIG. 1 .

FIG. 3 is a top view of the second metal separator of FIG. 2 .

4 is a cross-sectional view showing a cross-sectional shape along a plane perpendicular to a seal line of the protrusion seal of FIG. 1 .

FIG. 5A is a cross-sectional view of a boss seal according to a comparative example, and FIG. 5B is an explanatory view showing deformation of the boss seal according to the comparative example.

FIG. 6 is a cross-sectional view showing a stacked state of the raised seal member of FIG. 4 .

Detailed ways

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

As shown in Fig. 1 and Fig. 2, the power generation cell 10 (fuel cell) according to the present embodiment comprises: an electrolyte membrane-electrode assembly 12 with a resin frame (hereinafter referred to as "MEA 12 with a resin frame"), and metal separators 14 respectively arranged on both sides of the MEA 12 with a resin frame. The power generation cell 10 is, for example, a horizontally (or vertically) long rectangular solid polymer fuel cell.

A plurality of power generation cells 10 are stacked, for example, in the direction of arrow A (horizontal direction) or arrow C (gravity direction) and a tightening load (compression load) in the stacking direction is applied to form a fuel cell stack. The fuel cell stack is mounted on a fuel cell electric vehicle as a vehicle-mounted fuel cell stack.

As shown in FIG1 , at one end edge of the power generation cell 10 in the direction of arrow symbol B (horizontal direction), an oxidant gas inlet communication hole 18a, a cooling medium inlet communication hole 20a, and a fuel gas outlet communication hole 16b are provided in a manner connected in the stacking direction, i.e., the direction of arrow symbol A. The oxidant gas inlet communication hole 18a supplies an oxygen-containing gas (e.g., air) as an oxidant gas. The cooling medium inlet communication hole 20a supplies a cooling medium (e.g., water). The fuel gas outlet communication hole 16b discharges a hydrogen-containing gas as a fuel gas. The oxidant gas inlet communication hole 18a, the cooling medium inlet communication hole 20a, and the fuel gas outlet communication hole 16b are arranged separately in the direction of arrow symbol C (vertical direction).

The other end edge of the power generation unit cell 10 in the direction of arrow symbol B is provided with a fuel gas inlet communication hole 16a, a cooling medium outlet communication hole 20b, and an oxidant gas outlet communication hole 18b which are connected and extend in the direction of arrow symbol A. The fuel gas inlet communication hole 16a supplies fuel gas. The cooling medium outlet communication hole 20b discharges the cooling medium. The oxidant gas outlet communication hole 18b discharges the oxidant gas. The fuel gas inlet communication hole 16a, the cooling medium outlet communication hole 20b, and the oxidant gas outlet communication hole 18b are arranged separately in the direction of arrow symbol C.

In the power generating cell 10, the MEA 12 with a resin frame is sandwiched by the metal separator 14. Hereinafter, the metal separator 14 arranged on one surface of the MEA 12 with a resin frame is referred to as "the first metal separator 14a", and the metal separator 14 arranged on the other surface of the MEA 12 with a resin frame is referred to as "the second metal separator 14b". The first metal separator 14a and the second metal separator 14b are formed in a horizontally long (or vertically long) rectangular shape.

The MEA 12 with a resin frame includes an electrolyte membrane-electrode structure 12a (hereinafter referred to as "MEA 12a") and a resin frame member 22 that is bonded to the outer periphery of the MEA 12a and surrounds the outer periphery of the MEA 12a. The MEA 12a includes an electrolyte membrane 23, an anode electrode 24 provided on one surface 23a of the electrolyte membrane 23, and a cathode electrode 26 provided on the other surface 23b of the electrolyte membrane 23.

The electrolyte membrane 23 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water. The electrolyte membrane 23 is sandwiched between the anode electrode 24 and the cathode electrode 26. In addition to a fluorine-based electrolyte, the electrolyte membrane 23 can also use an HC (hydrocarbon)-based electrolyte.

As shown in Fig. 2, the anode electrode 24 includes: a first electrode catalyst layer 24a joined to one surface 23a of the electrolyte membrane 23; and a first gas diffusion layer 24b stacked on the first electrode catalyst layer 24a. The cathode electrode 26 includes: a second electrode catalyst layer 26a joined to the other surface 23b of the electrolyte membrane 23; and a second gas diffusion layer 26b stacked on the second electrode catalyst layer 26a.

The resin frame member 22 is a resin film (sub-gasket) whose inner periphery is joined to the outer periphery of the MEA 12a and whose plane shape is a rectangular frame. The resin film can also be composed of two overlapping resin films. The resin frame member 22 has a fixed thickness. In FIG1, an oxidant gas inlet connecting hole 18a, a cooling medium inlet connecting hole 20a and a fuel gas outlet connecting hole 16b are provided at one end of the resin frame member 22 in the direction of the arrow symbol B. The fuel gas inlet connecting hole 16a, the cooling medium outlet connecting hole 20b and the oxidant gas outlet connecting hole 18b are provided at the other end of the resin frame member 22 in the direction of the arrow symbol B. The connecting holes 16a, 16b, 18a, 18b, 20a, 20b provided in the resin frame member 22 are respectively set to the same shape as the connecting holes 16a, 16b, 18a, 18b, 20a, 20b provided in the first metal separator 14a and the second metal separator 14b.

As the constituent material of the resin frame member 22, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), silicone resin, fluororesin, m-PPE (modified polyphenylene ether resin), PET (polyethylene terephthalate), PBT (polybutylene terephthalate) or modified polyolefins are mentioned.

Furthermore, the electrolyte membrane 23 may be made to protrude outward without using the resin frame member 22. Alternatively, frame-shaped films may be provided on both sides of the electrolyte membrane 23 protruding outward from the anode electrode 24 and the cathode electrode 26.

The metal separator 14 has a metal plate 15 as a separator body. Hereinafter, when describing the structure of the metal plate 15 itself, the term "metal separator 14" may be used.

The metal plate 15 constituting the metal separator 14 is, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal thin plate subjected to a surface treatment for corrosion prevention, and is formed by stamping the cross section into a corrugated shape. The first metal separator 14a and the second metal separator 14b are joined together by welding, brazing, or caulking the outer periphery to form a joint separator 32. The plate thickness of the metal separator 14 can be, for example, 0.05 mm to 0.15 mm.

A fuel gas flow path 38 connected to the fuel gas inlet communication hole 16a and the fuel gas outlet communication hole 16b is provided on the surface 14as of the first metal separator 14a facing the MEA 12 with a resin frame. Specifically, the fuel gas flow path 38 is formed between the first metal separator 14a and the MEA 12 with a resin frame. The fuel gas flow path 38 has a plurality of linear flow grooves (or corrugated flow grooves) extending in the direction of the arrow symbol B.

As shown in Fig. 3, an oxidant gas flow path 40 connected to the oxidant gas inlet communication hole 18a and the oxidant gas outlet communication hole 18b is provided on the surface 14bs of the second metal separator 14b facing the MEA 12 with a resin frame. Specifically, the oxidant gas flow path 40 is formed between the second metal separator 14b and the MEA 12 with a resin frame. The oxidant gas flow path 40 has a plurality of linear flow grooves (or corrugated flow grooves) extending in the direction of the arrow symbol B.

In FIG. 1 , a coolant flow path 42 extending in the direction of arrow B and communicating with the coolant inlet passage 20 a and the coolant outlet passage 20 b is formed between the adjacent first metal separator 14 a and the second metal separator 14 b .

A first seal line 44 for preventing leakage of a fluid (fuel gas, oxidant gas or cooling medium) is provided on a surface 14as of the first metal separator 14a facing the MEA 12a by integrally stamping with the first metal separator 14a. The first seal line 44 surrounds the outer periphery of the first metal separator 14a. The first seal line 44 bulges (protrudes) toward the resin frame member 22 and abuts against the resin frame member 22 in an airtight and liquid-tight manner.

The first seal line 44 has a plurality of raised seals 45 (metal raised seals). The plurality of raised seals 45 have an outer raised seal 45a and an inner raised seal 45b provided on the inner side of the outer raised seal 45a. The inner raised seal 45b surrounds the fuel gas flow path 38, the fuel gas inlet communication hole 16a, and the fuel gas outlet communication hole 16b and connects them. The inner raised seal 45b has a plurality of communication hole raised portions 45c that surround the communication holes 16a, 16b, 18a, 18b, 20a, and 20b individually.

As shown in FIG3 , a second seal line 46 is provided on the surface 14bs of the second metal separator 14b facing the MEA 12a by integrally stamping the second metal separator 14b to surround the outer periphery of the second metal separator 14b to prevent fluid leakage. The second seal line 46 bulges toward the resin frame member 22 and abuts against the resin frame member 22 in an airtight and liquid-tight manner. The first seal line 44 and the second seal line 46 face each other across the resin frame member 22. The resin frame member 22 is sandwiched between the first seal line 44 and the second seal line 46.

The second seal line 46 has a plurality of raised seals 47 (metal raised seals). The plurality of raised seals 47 include an outer raised seal 47a and an inner raised seal 47b disposed inside the outer raised seal 47a. The inner raised seal 47b surrounds the oxidant gas flow path 40, the oxidant gas inlet communication hole 18a, and the oxidant gas outlet communication hole 18b and connects them. The inner raised seal 47b has a plurality of communication hole raised portions 47c that surround the communication holes 16a, 16b, 18a, 18b, 20a, and 20b individually.

As shown in FIG. 4 , the protruding seals 45 and 47 are formed to protrude from the bottom plate portion 15 a of the metal separator 14 (metal plate 15 ) toward the MEA 12 a in the stacking direction of the power generating cells 10 (the stacking direction of the MEA 12 a and the metal separator 14 ).

The protruding seal 45, when not stacked with the electrolyte membrane-electrode assembly 12a, that is, when no compressive load is applied in the stacking direction, has: a bent portion 51 including a top portion 50 protruding from the bottom plate portion 15a toward the MEA 12a in the stacking direction of the power generation unit cell 10 (the stacking direction of the MEA 12a and the metal separator 14); and side portions 52 and 53 connecting both ends of the bent portion 51 to the bottom plate portion 15a. The bent portion 51 is provided in the central portion (region E) in the width direction of the protruding seal 45, and is curved to be formed in an arc shape so as to protrude in a convex shape in the protruding direction of the top portion 50.

A top portion 50 that protrudes most in the stacking direction is formed at the center portion in the width direction of the curved portion 51. In addition, bent portions 52c and 53c with varying inclination angles are formed at both ends of the curved portion 51. The side portions 52 and 53 are formed in a region D between the bent portions 52c and 53c and the bottom plate portion 15a. The side portions 52 and 53 are inclined so as to gradually protrude from the reference position in the in-plane direction of the bottom plate portion 15a toward the MEA 12a as they move from the bottom plate portion 15a toward the curved portion 51. In the vicinity of the bent portions 52c and 53c, the inclination angle of the side portions 52 and 53 relative to the bottom plate portion 15a is smaller than the inclination angle of the curved portion 51, so that the side portions 52 and 53 are more easily deformed than the curved portion 51 in response to the compressive load in the stacking direction.

In the raised seal 45, the deformation mode of the raised seal 45 changes greatly with the bends 52c and 53c as the boundary. That is, the bent portion 51 forms a portion with a relatively large inclination angle near the bends 52c and 53c, thereby forming a portion that is difficult to deform with respect to the load input in the stacking direction. On the other hand, the side portions 52 and 53 form a smaller inclination angle than the bent portion 51, thereby being easily deformed with respect to the load in the stacking direction than the bent portion 51. The elastic coefficient K1 indicating the degree of deformation of the side portions 52 and 53 (bends 52c and 53c) with respect to the load in the stacking direction is formed to be smaller than the elastic coefficient K2 indicating the degree of deformation of the bent portion 51 with respect to the load in the stacking direction. Therefore, when a compressive load in the stacking direction is applied, the side portions 52 and 53 are elastically deformed before the bent portion 51. In this way, the side portions 52 and 53 constitute the spring portion of the raised seal 45 of this embodiment.

Furthermore, a thin film-shaped resin sealing member 49 may be provided on the surface near the top 50 of the protruding seal 45. For example, the resin sealing member 49 may be formed by a printing method or a coating method using polyester fiber. When the resin sealing member 49 is provided, the protruding seals 45 and 47 abut against the resin frame member 22 via the resin sealing member 49. The resin sealing member 49 may also be provided on the MEA 12 side.

The protruding seal 47 has a bent portion 61 protruding toward the MEA 12a in the opposite direction from the protruding seal 45, and side portions 62 and 63 connecting both ends of the bent portion 61 to the bottom plate portion 15a. The bent portion 61 is provided at the center portion (region E) in the width direction of the protruding seal 47, and is curved and formed in an arc shape so as to protrude in a convex shape in the protruding direction of the top portion 60.

A top portion 60 that protrudes most in the stacking direction is formed at the center portion in the width direction of the curved portion 61. In addition, bent portions 62c and 63c with varying inclination angles are formed at both ends of the curved portion 61. The side portions 62 and 63 are formed in a region D between the bent portions 62c and 63c and the bottom plate portion 15a. The side portions 62 and 63 are inclined so as to gradually protrude from the reference position in the in-plane direction of the bottom plate portion 15a toward the MEA 12a as they move from the bottom plate portion 15a toward the curved portion 61. In the vicinity of the bent portions 62c and 63c, the inclination angle of the side portions 62 and 63 relative to the bottom plate portion 15a is smaller than the inclination angle of the curved portion 61, so that the side portions 62 and 63 are more easily deformed than the curved portion 61 in response to the compressive load in the stacking direction.

In the raised seal 47, the deformation mode of the raised seal 47 changes greatly with the bent portions 62c and 63c as the boundary. That is, the bent portion 61 forms a portion with a relatively large inclination angle near the bent portions 62c and 63c, thereby forming a portion that is difficult to deform with respect to the load input in the stacking direction. On the other hand, the side portions 62 and 63 form a smaller inclination angle than the bent portion 61, thereby being easily deformed with respect to the load in the stacking direction than the bent portion 61. The elastic coefficient K1 indicating the degree of deformation of the side portions 62 and 63 (bend portions 62c and 63c) with respect to the load in the stacking direction is formed to be smaller than the elastic coefficient K2 indicating the degree of deformation of the bent portion 61 with respect to the load in the stacking direction. Therefore, when a compressive load in the stacking direction is applied, the side portions 62 and 63 are elastically deformed before the bent portion 61. In this way, the side portions 62 and 63 constitute the spring portion of the raised seal 47 of the present embodiment.

Furthermore, the protrusion seal 47 is preferably formed symmetrically with the protrusion seal 45 in the stacking direction, but may have a part that is asymmetrical in the stacking direction. In addition, a thin film-shaped resin sealing member 49 may be provided on the surface near the top 60 of the protrusion seal 47. The resin sealing member 49 is the same as the resin sealing member 49 provided on the protrusion seal 45.

The operation and effect of the power generating cell 10 configured as described above will be described below.

1, an oxidant gas such as oxygen-containing gas is supplied to the oxidant gas inlet passage 18a, and a fuel gas such as hydrogen-containing gas is supplied to the fuel gas inlet passage 16a. A coolant such as pure water, ethylene glycol, or oil is supplied to the coolant inlet passage 20a.

Therefore, the oxidant gas is introduced from the oxidant gas inlet passage 18a to the oxidant gas flow path 40 of the second metal separator 14b, and the oxidant gas moves in the direction of the arrow symbol B and is supplied to the cathode electrode 26 of the MEA 12a. On the other hand, the fuel gas is introduced from the fuel gas inlet passage 16a to the fuel gas flow path 38 of the first metal separator 14a. The fuel gas moves in the direction of the arrow symbol B along the fuel gas flow path 38 and is supplied to the anode electrode 24 of the MEA 12a.

Therefore, in the MEA 12 a , the oxidant gas supplied to the cathode electrode 26 and the fuel gas supplied to the anode electrode 24 are consumed by electrochemical reactions in the second electrode catalyst layer 26 a and the first electrode catalyst layer 24 a , thereby generating electricity.

1 , the oxidant gas supplied to the cathode electrode 26 and consumed is discharged along the oxidant gas outlet passage 18b in the direction of arrow A. Similarly, the fuel gas supplied to the anode electrode 24 and consumed is discharged along the fuel gas outlet passage 16b in the direction of arrow A.

The coolant supplied to the coolant inlet passage 20a is introduced into the coolant flow path 42 between the first metal separator 14a and the second metal separator 14b and then flows in the direction of arrow B. The coolant cools the MEA 12a and is then discharged from the coolant outlet passage 20b.

In this case, the power generating cell 10 including the metal separator 14 according to the present embodiment produces the following effects.

In FIG. 5A , the cross-sectional shape of the protruding seal 45A of the metal separator involved in the comparative example has an arc-shaped curved portion 51A protruding in a manner that the top 50 is the highest in the initial state without applying a compressive load. As shown in FIG. 5B , when a compressive load is applied to the protruding seal 45A, the top 50 of the central portion in the width direction of the protruding seal 45A is pushed and deformed in a manner that expands in the width direction as shown by arrow symbols S1 and S2, and deforms in the stacking direction (arrow symbol d direction). At this time, since the rigidity of the protruding seal 45A in the width direction is high, the top 50 is concave as shown by the solid line P2, and thus deforms in a manner that eases the deformation in the width direction. In this way, when the cross-sectional shape of the protruding seal 45A is deformed into an M-shape, the surface pressure near the central top 50 (the central portion of the protruding width direction) is reduced. As a result, the desired sealing cannot be ensured, and there is a risk of fluid leakage.

In contrast, as shown in FIG6 , in the metal partition 14 according to the present embodiment, the protruding seals 45 and 47 are provided with side portions 52, 53, 62, and 63 (spring portions) having softer spring characteristics than the curved portions 51 and 61. Therefore, when a compressive load is applied to the protruding seals 45 and 47, the side portions 52, 53, 62, and 63 are deformed and reacted before the curved portions 51 and 61. Thus, it is possible to prevent the load and deformation from being concentrated on the top portions 50 and 60 of the curved portions 51 and 61 and the vicinity of the top portions 50 and 60 from being sunken into a concave shape. As a result, the top portions 50 and 60 of the protruding seals 45 and 47 are in contact with the resin frame member 22 with sufficient surface pressure, thereby ensuring good sealing performance.

The fuel cell metal separator 14 and the power generating cell 10 of the present embodiment produce the following effects.

The fuel cell metal separator 14 of this embodiment is stacked on an electrolyte membrane-electrode structure 12a formed by arranging electrodes 24 and 26 on both sides of an electrolyte membrane 23 to form a power generation cell 10. The protruding seals 45 and 47 for preventing leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium protrude in the stacking direction with the electrolyte membrane-electrode structure 12a. In the fuel cell metal separator 14, there are two protruding seals 45 and 47. The bottom plate portion 15a is a flat portion on the side and perpendicular to the stacking direction. The raised seals 45 and 47 have, in an initial state where they are not compressed in the stacking direction,: a bent portion 51, 61 protruding from the bottom plate portion in the stacking direction; bent portions 52c, 53c, 62c, 63c arranged on both sides of the bent portions 51, 61; and a spring portion (side portions 52, 53, 62, 63) extending obliquely from the bent portions 52c, 53c, 62c, 63c toward the bottom plate portion 15a.

By configuring as described above, when a compressive load is applied to the protruding seals 45 and 47, the side portions 52, 53, 62 and 63 constituting the spring portion deform and generate a reaction force before the curved portions 51 and 61. This prevents the load and deformation from being concentrated on the top portions 50 and 60 (sealing surfaces) of the curved portions 51 and 61 and the vicinity of the top portions 50 and 60 from being sunken into a concave shape. As a result, the top portions 50 and 60 of the protruding seals 45 and 47 abut against the resin frame member 22 with sufficient surface pressure, and the desired sealing performance can be ensured.

In the above-described fuel cell metal separator 14 , the spring portion (side portions 52 , 53 , 62 , 63 ) may be inclined so as to protrude from the bottom plate portion 15 a in the stacking direction as it moves from the bottom plate portion 15 a toward the bent portions 51 , 61 .

As described above, by inclining the spring portion (side portions 52 , 53 , 62 , 63 ), the side portions 52 , 53 , 62 , 63 can exhibit soft spring characteristics that are deformable in the stacking direction under a compressive load.

In the above-mentioned fuel cell metal separator 14, the inclination of the spring portion (side portion 52, 53, 62, 63) may be formed to be gentler than the inclination of the bent portion 51, 61 near the bent portion 52c, 53c, 62c, 63c. With such a configuration, the spring portion (side portion 52, 53, 62, 63) is not strained by the load in the stacking direction and can be flexibly deformed.

In the above-described fuel cell metal separator 14, the spring portion (side portions 52, 53, 62, 63) can be set to have softer spring characteristics than the curved portions 51, 61. This can prevent deformation of the sealing surface and ensure good sealing performance.

The bonded separator 32 of this embodiment is a bonded separator 32 formed by stacking a plurality of the above-mentioned fuel cell metal separators 14, and the adjacent fuel cell metal separators 14 are bonded in such a manner that the tops 50 and 60 of the respective protruding seals 45 and 47 protrude in opposite directions in the stacking direction. This prevents deformation of the sealing surface and ensures good sealing performance.

The power generation cell 10 of this embodiment comprises: an electrolyte membrane-electrode structure 12a formed by respectively arranging electrodes 24 and 26 on both sides of an electrolyte membrane 23; and metal separators 14 respectively arranged on both sides of the electrolyte membrane-electrode structure 12a, and on the metal separators 14, protruding seals 45 and 47 are formed in a stacking direction of the electrolyte membrane-electrode structure 12a and the metal separators 14 to prevent leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium. In the power generation cell, there is The bottom plate portion 15a is a flat portion on both sides of the protruding seals 45 and 47 and is perpendicular to the stacking direction. In the initial state where the protruding seals 45 and 47 are not compressed in the stacking direction, the protruding seals 45 and 47 have: a curved portion 51 and 61 protruding from the bottom plate portion in the stacking direction; a bent portion 52c, 53c, 62c, 63c provided on both sides of the curved portion 51 and 61; and a spring portion (side portion 52, 53, 62, 63) extending obliquely from the bent portion 52c, 53c, 62c, 63c toward the bottom plate portion 15a. As a result, it is possible to prevent the load and deformation from being concentrated on the top 50 and 60 of the curved portion 51 and 61 and the vicinity of the top 50 and 60 from being concave. As a result, the top 50 and 60 of the protruding seals 45 and 47 abut against the resin frame member 22 with sufficient surface pressure, and good sealing can be ensured.

In the above, the present invention has been described by taking suitable embodiments as examples, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

Claims (4)

1. A metal separator for a fuel cell, which is stacked with an electrolyte membrane-electrode structure (12a) formed by arranging electrodes (24, 26) on both sides of an electrolyte membrane (23) to form a power generation cell (10), wherein a protruding seal (45, 47) for preventing leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium protrudes in the stacking direction with the electrolyte membrane-electrode structure, and in the metal separator (14) for a fuel cell, having flat portions on both sides of the raised seal and having a bottom plate portion (15a) perpendicular to the stacking direction, The raised seal comprises, in an initial state when not compressed in the stacking direction: a bent portion (51, 61) protruding from the bottom plate portion in the stacking direction; bent portions (52c, 53c, 62c, 63c) provided on both sides of the bent portion; and a spring portion (52, 53, 62, 63) extending obliquely from the bent portion toward the bottom plate portion, The spring portion is inclined so as to protrude from the position of the bottom plate portion in the stacking direction as it moves from the bottom plate portion toward the bent portion. The inclination of the spring portion is formed to be gentler than the inclination of the bent portion near the bent portion. 2. The metal separator for a fuel cell according to claim 1, characterized in that: The spring portion has a softer spring characteristic with respect to a load in a stacking direction than the bent portion. 3. A joined separator, which is a joined separator formed by joining a plurality of metal separators for fuel cells according to claim 1, wherein adjacent metal separators for fuel cells are joined in the following manner: the tops (50, 60) of the respective raised seals protrude in opposite directions to each other in the stacking direction. 4. A power generation cell, comprising: an electrolyte membrane-electrode structure formed by arranging electrodes on both sides of an electrolyte membrane; and metal separators arranged on both sides of the electrolyte membrane-electrode structure, wherein a protruding seal for preventing leakage of a fluid such as a fuel gas, an oxidant gas or a cooling medium is formed protrudingly on the metal separator in the stacking direction of the electrolyte membrane-electrode structure and the metal separator, wherein in the power generation cell (10), having flat portions on both sides of the raised seal and having a bottom plate portion perpendicular to the stacking direction, The protruding seal member, in an initial state where it is not compressed in the stacking direction, comprises: a bent portion protruding from the bottom plate portion in the stacking direction; bent portions provided on both sides of the bent portion; and a spring portion extending obliquely from the bent portion toward the bottom plate portion. The spring portion is inclined so as to protrude from the position of the bottom plate portion in the stacking direction as it moves from the bottom plate portion toward the bent portion. The inclination of the spring portion is formed to be gentler than the inclination of the bent portion near the bent portion.