JP2008047320A - Fuel cell - Google Patents

Abstract

An object of the present invention is to suppress excessive cooling of a fuel cell, to prevent deterioration of power generation efficiency, and to improve startability of the fuel cell at a low temperature.
A first plate 200 and a second plate disposed on one surface side of the first plate, the first plate 200 projecting toward the first plate side, and a top portion of the first plate is formed on the first plate. A second plate 300 having a convex portion 340 in contact therewith and a space forming portion 342 that forms at least one sealed space 18 together with the first plate, and is disposed on the other surface side of the first plate, A plate that sandwiches the first plate together with the plate, is convex toward the first plate, is formed at a location where the top is in contact with the first plate and does not face the convex portion of the second plate. A fuel cell formed by alternately laminating a separator having a third plate 400 having a convex portion 440 and a membrane electrode assembly.
[Selection] Figure 7

Description

  The present invention relates to a fuel cell, and more particularly to a structure of a fuel cell separator.

  The fuel cell includes a separator that separates the fuel gas and the oxidizing gas so that the fuel gas and the oxidizing gas do not directly contact each other. As a conventional fuel cell separator structure, there is known a three-layer separator in which a leaf spring is interposed between a pair of metal plates each having a portion in which convex portions and concave portions are alternately continuous (patents). Reference 1). Since the reaction of the fuel cell generates electric power and heat, the conventional fuel cell cools the fuel cell by flowing cooling water into the space between each metal plate and the leaf spring.

JP 2002-367665 A

  However, the electrochemical reaction that takes place at the anode electrode in the fuel cell reaction is not an exothermic reaction, so if cooling water is passed through the space formed by the concave part of the metal plate on the anode side and the leaf spring, the fuel cell will overcool. However, there has been a problem that the performance of the fuel cell is lowered, or the startability of the fuel cell at a low temperature is deteriorated.

  The object of the present invention is to solve at least a part of the above-mentioned problems, suppress excessive cooling of the fuel cell, prevent deterioration of the performance of the fuel cell, and improve the startability of the fuel cell at a low temperature. With the goal.

  In order to solve the above problems, a fuel cell according to the present invention provides a fuel cell in which separators and membrane electrode assemblies are alternately stacked. The separator is a first plate and a second plate disposed on one surface side of the first plate, and protrudes toward the first plate, and a top portion is the first plate. A second plate comprising a plurality of convex portions in contact with the plate and a space forming portion for forming at least one sealed space between the first plate and the other surface side of the first plate A third plate sandwiching the first plate together with the second plate, wherein the third plate is convex toward the first plate, the top is in contact with the first plate, and the first plate And a third plate having a plurality of convex portions formed in a place not overlapping with the convex portions of the second plate.

  In the fuel cell according to the present invention, the first plate and the second plate form at least one sealed space. Since cooling water does not flow into the sealed space, excessive cooling of the fuel cell can be suppressed. As a result, the performance degradation of the fuel cell is suppressed, and the startability of the fuel cell at a low temperature can be improved.

  In the fuel cell according to the present invention, it is preferable that the space forming portion is a concave portion that is formed substantially at the center of the second plate and has the convex portion. According to the fuel cell of the present invention, the concave portion is formed at substantially the center of the second plate, and the first plate and the outer peripheral portion of the second plate are sealed to form the first plate. The space formed by the concave portions is a sealed space, and cooling water does not flow in the sealed space, so that excessive cooling of the fuel cell can be suppressed. As a result, the performance degradation of the fuel cell is suppressed, and the startability of the fuel cell at a low temperature can be improved.

  In the fuel cell according to the aspect of the invention, the space forming portion may include a third convex portion between both ends of the first convex portion of the second plate and both ends of the second convex portion adjacent to the first convex portion. It is preferable that it is a recessed part formed by being surrounded by the 3rd convex part from the said 1st convex part by connecting by a part. According to the present invention, a plurality of sealed spaces can be formed by the concave portions surrounded by the convex portions of the first plate and the second plate. The amount of cooling water flowing between the first plate and the second plate can be adjusted by the number of sealed spaces, and the fuel cell can be cooled appropriately. As a result, the power generation efficiency of the fuel cell can be improved.

  In the fuel cell according to the present invention, it is preferable that the third plate further includes a space forming portion for forming at least one sealed space between the third plate and the first plate. According to the fuel cell according to the present invention, since at least one sealed space is formed between the first plate and the third plate, cooling of the fuel cell is further suppressed, and deterioration of the performance of the fuel cell is suppressed. Can do.

  In the fuel cell according to the present invention, it is preferable that the space forming portion is a concave portion that is formed substantially at the center of the third plate and has the convex portion. According to the fuel cell of the present invention, the concave portion is formed at substantially the center of the outer peripheral portion of the third plate, and the first plate and the outer peripheral portion of the third plate are sealed to form the first plate. The space formed by the one plate and the concave portion is one sealed space, and cooling water does not flow in the sealed space, so that excessive cooling of the fuel cell can be suppressed. As a result, the performance degradation of the fuel cell is suppressed, and the startability of the fuel cell at a low temperature can be improved.

    In the fuel cell according to the aspect of the invention, the space forming portion may include a third convex portion between both ends of the first convex portion of the third plate and both ends of the second convex portion adjacent to the first convex portion. It is preferable that it is a recessed part formed by being surrounded by the 3rd convex part from the said 1st convex part by connecting by a part. According to the present invention, a plurality of sealed spaces can be formed by the concave portions surrounded by the convex portions of the first plate and the third plate. The amount of cooling water flowing between the first plate and the third plate can be adjusted by the number of sealed spaces, and the fuel cell can be appropriately cooled. As a result, the power generation efficiency of the fuel cell can be improved.

  In the fuel cell according to the present invention, it is preferable that the number of the sealed spaces is larger as the separator is closer to the end portion of the fuel cell and is smaller as the separator is closer to the center portion of the fuel cell. In the fuel cell, the heat generated at the center of the stack tends to be trapped, and the heat generated at the end of the stack is not easily trapped, but the fuel cell according to the present invention can strongly cool the center of the stack, Since the cooling of the end can be weakened, the temperature distribution of the fuel cell can be suppressed. As a result, the reactivity depending on the location of the fuel cell can be made uniform.

  In the fuel cell according to the present invention, the sealed space is preferably filled with a gas or a vacuum space. According to the fuel cell of the present invention, the sealed space is filled with gas or is a vacuum space. Since gas has higher heat insulation than solid and liquid, heat hardly escapes from the fuel cell even when the outside air temperature is low. As a result, even if the outside air temperature is low, the fuel cell does not become low temperature, and the startability of the fuel cell can be improved. Further, if the sealed space is evacuated, there is no medium that conducts heat, so that the heat insulation is further improved, and the startability of the fuel cell at a low temperature can be further improved. Further, if the sealed space is evacuated, for example, the adhesive strength between the plates can be increased.

  In the fuel cell according to the present invention, it is preferable that a cooling medium capable of supercooling is enclosed in at least a part of the sealed space. According to the fuel cell of the present invention, a cooling medium that can be supercooled is enclosed in at least a part of the sealed space. A supercooled liquid undergoes a phase transition from a liquid to a solid and generates heat upon impact. Since the fuel cell is heated by the heat generated with the phase transition, the startability of the fuel cell at a low temperature can be improved.

  In the fuel cell according to the present invention, the supercoolable cooling medium is preferably sodium acetate. Sodium acetate is readily available, and sodium acetate trihydrate, a hydrate of sodium acetate, has a melting point of 58 ° C. and is a solid substance at room temperature, but when the temperature falls from a high temperature liquid state, Even if the temperature is 58 ° C. or lower, it does not become solid and tends to be supercooled. Furthermore, sodium acetate trihydrate easily changes phase to a solid and generates heat when shocked in a supercooled state. Therefore, the fuel cell can be easily heated by sealing sodium acetate trihydrate in a sealed space and shocking the supercooled sodium acetate trihydrate. As a result, the startability of the fuel cell can be improved.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing the appearance of a fuel cell 100 according to an embodiment of the present invention. The fuel cell 100 is configured by alternately laminating separators 102 and membrane electrode assemblies (MEA) 104. The fuel cell 100 includes three manifolds, ie, a fuel gas discharge manifold 112, an oxidizing gas supply manifold 120, and a cooling water supply manifold 130 that penetrate in the stacking direction on the upper side, and fuel that penetrates in the stacking direction on the lower side. Three manifolds are provided: a gas supply manifold 110, an oxidizing gas discharge manifold 122, and a cooling water discharge manifold 132.

  The structure of the separator 102 will be described with reference to FIG. FIG. 2 is an explanatory diagram schematically showing the structure of the separator 102. The separator 102 is a separator having a three-layer structure including an intermediate plate 200 that is a first plate, an anode side plate 300 that is a second plate, and a cathode side plate 400 that is a third plate. The anode side plate 300 is disposed on the lower surface of the intermediate plate 200, the cathode side plate 400 is disposed on the upper surface of the intermediate plate, and the intermediate plate 200 is sandwiched between the anode side plate 300 and the cathode side plate 400. The cathode side plate 400 is formed with a concave portion 449 that is recessed when viewed from the intermediate plate 200 side and a convex portion 440 that is convex toward the intermediate plate 200.

  Three plates constituting the separator 102 will be described with reference to FIGS. 3A is a plan view schematically showing the intermediate plate 200, FIG. 3B is a cross-sectional view of the intermediate plate 200 taken along line 1-1 in FIG. 3A, and FIG. FIG. 4B is a plan view schematically showing the anode side plate 300, FIG. 4B is a cross-sectional view of the anode side plate 300 of FIG. 4A cut along line 2-2, and FIG. 4C is FIG. 3) is a cross-sectional view of the anode side plate 300 taken along line 3-3. 5A is a plan view schematically showing the cathode side plate 400, FIG. 5B is a cross-sectional view of the cathode side plate 400 of FIG. 5A cut along line 4-4, and FIG. ) Is a cross-sectional view of the cathode side plate 400 of FIG. 5A cut along line 5-5.

  The intermediate plate 200 is a substantially rectangular flat plate member having a size substantially the same as the outermost periphery of the concave portion 449 of the cathode side plate 400.

  The anode side plate 300 is a substantially rectangular plate-like member, and a fuel gas discharge hole 312 that constitutes a part of the fuel gas discharge manifold 112 and a part of the oxidizing gas supply manifold 120 are provided above the outer peripheral portion 348. The oxidizing gas supply hole 320 and the cooling water supply hole 330 constituting a part of the cooling water supply manifold 130 are provided, and the fuel gas constituting a part of the fuel gas supply manifold 110 is provided below the outer peripheral part 348. A supply hole 310, an oxidizing gas discharge hole 322 constituting a part of the oxidizing gas discharge manifold 122, and a cooling water discharge hole 332 constituting a part of the cooling water discharge manifold 132 are provided.

  As shown in FIGS. 4B and 4C, the anode-side plate 300 has a concave portion 349 and a concave portion 349 that are substantially the same size as the intermediate plate 200 in the portion excluding the outer peripheral portion 348, that is, in the approximate center. And a convex portion 340 that is convex toward the intermediate plate 200 side. Here, a portion of the concave portion 349 in which a dent is formed by the convex portion 340 is referred to as a concave portion 342. That is, the anode side plate 300 has a concave cross-sectional shape in which only the concave portion 349 appears as shown in FIG. 4B, for example, in a cross section taken along line 2-2. In the cut section, as shown in FIG. 4C, the convex portion 340 and the concave portion 342 have a corrugated cross-sectional shape that is continuous with each other. When the separator 102 is assembled, as shown in FIG. 4B, the concave portion 349 of the anode side plate 300 forms the anode side space 12 together with the intermediate plate 200. The anode side space 12 becomes a sealed space 18 if there is no supply port or discharge port for cooling water. That is, the concave portion 349 functions as a space forming portion. Further, the top of the convex portion 340 of the anode side plate 300 is in contact with the intermediate plate 200. In the present embodiment, a portion protruding toward the intermediate plate 200 is referred to as a convex portion, and a portion that is recessed when viewed from the intermediate plate 200 side between the convex portions is referred to as a concave portion.

  The cathode-side plate 400 is a substantially rectangular plate-shaped member, and a fuel gas discharge hole 412 that constitutes a part of the fuel gas discharge manifold 112 and a part of the oxidizing gas supply manifold 120 are formed above the outer peripheral portion 448. The oxidizing gas supply hole 420 and the cooling water supply hole 430 that constitute a part of the cooling water supply manifold 130 are provided, and the fuel gas that constitutes a part of the fuel gas supply manifold 110 is provided below the outer peripheral part 448. A supply hole 410, an oxidizing gas discharge hole 422 constituting a part of the oxidizing gas discharge manifold 122, and a cooling water discharge hole 432 constituting a part of the cooling water discharge manifold 132 are provided.

  As shown in FIGS. 5B and 5C, the cathode side plate 400 has a concave portion 449 and a concave portion 449 that are substantially the same size as the intermediate plate 200 in a portion excluding the outer peripheral portion 448. And a plurality of convex portions 440 that are formed and convex toward the intermediate plate 200 side. Here, a portion of the concave portion 449 in which a dent is formed by the convex portion 440 is referred to as a concave portion 442. That is, for example, the cathode-side plate 400 has a concave cross-sectional shape in which only the concave portion 449 appears as shown in FIG. 5B in the cross-section taken along line 4-4. In the cut section, as shown in FIG. 5C, the convex portion 440 and the concave portion 442 have a corrugated cross-sectional shape that is continuous with each other. When the separator 102 is assembled, as shown in FIG. 5B, the concave portion 449 of the cathode side plate 400 forms the cathode side space 16 together with the intermediate plate 200. The cathode side space 16 becomes a sealed space 18 if there is no supply port or discharge port for cooling water. That is, the concave portion 449 functions as a space forming portion. Further, the top of the convex portion 440 of the cathode side plate 400 is in contact with the intermediate plate 200. In the cathode side plate 400, as in the anode side plate 300, a portion protruding toward the intermediate plate 200 side is called a convex portion, and a portion recessed between the convex portion and the convex portion when viewed from the intermediate plate 200 side. This is called a recess.

  The membrane electrode assembly 104 will be described with reference to FIG. 6A is a plan view schematically showing the configuration of the membrane electrode assembly 104, and FIG. 6B is a cross-sectional view of the membrane electrode assembly 104 in FIG. 6A taken along line 6-6. FIG. The membrane electrode assembly 104 includes an electrolyte membrane 540, a porous body 542 sandwiching the electrolyte membrane 540 from both sides, and a resin frame 500 that fits and supports the electrolyte membrane 540 and the porous body 542. .

  The electrolyte membrane 540 includes a proton conductive ion exchange membrane made of a solid polymer material, for example, a fluorine-based resin such as perfluorocarbon sulfonic acid polymer, and a catalyst electrode layer. As the catalyst electrode layer, a catalyst that promotes an electrochemical reaction, for example, a platinum catalyst or a platinum alloy catalyst made of platinum and another metal is used. The porous body 542 is a porous member made of a metal material or a carbon material, and diffuses fuel gas or oxidizing gas. The fuel gas or oxidizing gas that has passed through the porous body 542 causes an electrochemical reaction in the catalyst electrode layer, and the fuel cell 100 generates power.

  The resin frame 500 is a substantially rectangular member, and has a fuel gas discharge hole portion 512 forming a part of the fuel gas discharge manifold 112 at an upper portion and an oxidation gas supply hole portion forming a part of the oxidation gas supply manifold 120. 520, a cooling water supply hole 530 that constitutes a part of the cooling water supply manifold 130, and a fuel gas supply hole 510 that constitutes a part of the fuel gas supply manifold 110, and an oxidizing gas discharge manifold 122. An oxidizing gas discharge hole 522 constituting a part and a cooling water discharge hole 532 constituting a part of the cooling water discharge manifold 132 are provided.

  The resin frame 500 has an electrolyte membrane fitting opening 544 formed at the center, and the resin frame 500 has the electrolyte membrane 540 and the porous body 542 fitted in the electrolyte membrane fitting opening 544.

  The structure of the fuel cell 100 will be described in detail with reference to FIGS. FIG. 7 is a cross-sectional view schematically showing a part of a cross section taken along line 7-7 of the fuel cell 100 shown in FIG. FIG. 8 is a cross-sectional view schematically showing a part of the cross section taken along line 8-8 of the fuel cell 100 shown in FIG.

  The top of the convex portion 340 of the anode side plate 300 is in contact with the intermediate plate 200. The inner periphery of the outer peripheral portion 348 of the anode side plate 300 is sealed in contact with the outer periphery of the intermediate plate 200. As a result, the concave portion 342 of the anode side plate 300 and the intermediate plate 200 form the anode side space 12. Here, the anode-side space 12 is a closed sealed space 18 that is not connected to the cooling water supply manifold 130 or the cooling water discharge manifold 132, and is filled with a gas such as air, so that the cooling water does not flow.

  On the other hand, in the space between the convex portion 340 and the porous body 542 on the opposite side of the intermediate plate of the anode side plate 300, the fuel gas buffer 10 that temporarily holds the fuel gas is formed. The fuel gas buffer 10 is a low-pressure loss part, and the fuel gas supplied from the fuel gas supply manifold 110 is temporarily held in the fuel gas buffer 10 and diffuses in the porous body 542 to be the anode side electrode catalyst layer. To reach. In this embodiment, hydrogen gas is used as the fuel gas, and the electrochemical reaction at the anode electrode of the fuel cell is as follows.

Anode electrode: H ₂ → 2H ⁺ + 2e ⁻ (1)

  Here, the electrochemical reaction (1) at the anode electrode is not an exothermic reaction. Therefore, when cooling water is allowed to flow through the anode-side space 12, the anode electrode is excessively cooled, and the reactivity of the electrochemical reaction may be reduced. However, in this embodiment, all the anode-side spaces 12 are sealed spaces 18, and cooling water does not flow into the sealed spaces 18, so the anode-side plate 300 is not cooled. Therefore, the anode electrode is not excessively cooled, and the reactivity of the electrochemical reaction of the anode electrode does not decrease. As a result, the performance degradation of the fuel cell can be suppressed.

  In this embodiment, the anode side space 12 is a sealed space 18 filled with a gas such as air. Since gas has higher heat insulation than liquid and solid, for example, even when the outside air temperature is low, the heat of the fuel cell 100 is blocked by the sealed space 18 and is difficult to escape. That is, even if the outside air temperature is low, the MEA 104 of the fuel cell 100 is not easily affected by the MEA 104 and is not easily lowered. As a result, the startability of the fuel cell 100 can be improved even when the outside air temperature is low.

  The top of the convex portion 440 of the cathode side plate 400 is in contact with the intermediate plate 200. The inner periphery of the outer peripheral portion 448 of the cathode side plate 400 is sealed in contact with the outer periphery of the intermediate plate 200. As a result, the cathode side space 16 surrounded by the concave portion 442 of the cathode side plate 400 and the intermediate plate 200 is formed. However, unlike the anode side space 12, the cathode side space 16 is connected to the cooling water supply manifold 130 by forming a cooling water supply opening 534 in the direction of the cooling water supply manifold 130 as shown in FIG. . Therefore, the cathode side space 16 is not the sealed space 18. A cooling water discharge opening (not shown) is also formed in the cathode side space 16 in the direction of the cooling water discharge manifold 132, and the cathode side space 16 is also connected to the cooling water discharge manifold 132. The cooling water is supplied from the cooling water supply manifold 130 through the cooling water supply opening 534 to the cathode side space 16 to cool the fuel cell 100. The cooling water cools the fuel cell 100 and then is discharged to the cooling water discharge manifold 132 through the cooling water discharge opening.

  Between the convex part 440 of the cathode side plate 400 and the porous body 542, the oxidizing gas buffer 14 that temporarily holds the oxidizing gas is formed. The oxidizing gas buffer 14 is a low-pressure loss part, and the oxidizing gas supplied from the oxidizing gas supply manifold 120 is temporarily held in the oxidizing gas buffer 14 and diffuses in the porous body 542 to be the cathode side catalyst electrode layer. To reach. In this embodiment, air is used as the oxidizing gas, and the electrochemical reaction at the cathode electrode is as follows.

Cathode electrode: (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)

  Here, the cathode reaction (2) is an exothermic reaction. Therefore, when the cooling water does not flow into the cathode side space 16, the cathode electrode may be heated to a high temperature by the reaction heat. However, according to the present embodiment, the cathode electrode is cooled by flowing the cooling water through the cathode side space 16 to cool the cathode side plate 400, and the cathode side plate 400 is cooled. The cathode electrode is not heated too much, and the cathode electrode electrochemical reaction can be performed at an appropriate temperature. As a result, the power generation efficiency and durability of the fuel cell can be improved.

  As described above, according to the fuel cell 100 according to the present embodiment, the anode side space 12 on the anode side that is not an exothermic reaction is used as the sealed space 18 and cooling water is not flown, so the anode side of the fuel cell 100 is excessively cooled. Will never be done. Therefore, it can suppress that the reactivity of the electrochemical reaction of an anode electrode falls, and the performance of a fuel cell falls.

  In the fuel cell according to the present embodiment, the sealed space 18 is formed by the intermediate plate 200 that is the first plate and the concave portion 349 of the anode side plate 300 that is the second plate. Since cooling water does not flow, excessive cooling of the fuel cell 100 can be suppressed. As a result, the performance degradation of the fuel cell 100 is suppressed, and the startability of the fuel cell 100 at a low temperature can be improved.

  Moreover, since the sealed space 18 is filled with gas, the heat insulating property is high. Therefore, even if the outside air temperature is low, the heat of the fuel cell is blocked by the sealed space 18 and is difficult to escape, so the MEA 104 of the fuel cell 100 is unlikely to become low temperature. As a result, even when the outside air temperature is low, the fuel cell 100 is unlikely to become low temperature, and the startability of the fuel cell 100 can be improved.

  In addition, according to the present embodiment, the fuel cell 100 has a so-called groove structure in the anode side plate 300 and the cathode side plate 400, so that the fuel gas buffer 10 and the oxidizing gas buffer 14 have low pressure loss portions. . By having this low pressure loss part, the pressure distribution of the porous body 542 can be relaxed and gas diffusion can be promoted. As a result, the electrochemical reaction of the fuel cell can be made uniform and the performance can be improved.

  Further, since the intermediate plate 200 acts as a spring material with respect to the anode side plate 300 and the cathode side plate 400, when the entire fuel cell stack is fixed at a fixed size by the repulsive force due to the spring effect of the intermediate plate 200, It is possible to leave a repulsive force inside and leave a constant fastening pressure inside. Therefore, for example, a disc spring or the like that has been used for giving a fastening force can be eliminated, and the volume of the fuel cell stack can be reduced.

(Modification 1)
In the present embodiment, the anode side space 12 has been described as the sealed space 18 that is not connected to the cooling water supply manifold 130 and the cooling water discharge manifold 132. However, the cooling water supply manifold 130 and the cooling water discharge to the anode side space 12 are described. It may be connected to the manifold 132 as an open space, a part of the anode-side space 12 may be a sealed space 18, and cooling water may be allowed to flow into the anode-side space 12 other than the sealed space 18. If at least a part is a sealed section, excessive cooling can be suppressed as compared with the case where cooling water flows in all the anode-side spaces 12.

  For that purpose, the shape of the anode side plate 301 may be made such that, for example, the convex portion 340 is connected by the adjacent convex portion 340 and the convex portion 346 as shown in FIG. Fig.9 (a) is a top view which shows typically the anode side plate 301 which concerns on the modification 1, FIG.9 (b) shows the anode side plate 301 in Fig.9 (a) by 9-9 line | wire. It is sectional drawing cut | disconnected. In the anode side plate 301 according to the modified example 1, a part of the convex portion 340 is connected to the end portion 344 of the adjacent convex portion 340 by the end portion 344 and the convex portion 346. As a result, the portion surrounded by the convex portion 340 and the convex portion 346 forms the sealed space 18 together with the intermediate plate 200 when the separator 102 is assembled. That is, the concave portion 343 surrounded by the convex portion 340 and the convex portion 346 functions as a space forming portion. Here, by providing the cooling water supply opening and the cooling water discharge opening in the anode side space 12 formed by the recess 342 not surrounded by the protrusion 340 and the protrusion 346 and the intermediate plate 200, A part of the anode space 12 can be used as the sealed space 18 and the remaining space can be used as the open space to allow the cooling water to flow. Note that the number of sealed spaces 18 can be changed by changing the number and location of the protrusions 346. As a result, the fuel cell 100 can be appropriately cooled.

(Modification 2)
In this embodiment, the cathode side space 16 is an open space, but the cathode side space 16 may be a sealed space 18. That is, in this embodiment, the intermediate plate 200 and the outer peripheral portion 448 of the cathode side plate 400 are sealed in contact with each other, but the cooling water supply opening 534 and the cooling water discharge opening are provided. Although the side space 16 is an open space, the cathode side space 16 can be a sealed space 18 if the side space 16 is closed without providing the cooling water supply opening 534 and the cooling water discharge opening. According to this modification, since cooling water does not flow between the intermediate plate 200 and the cathode side plate 400, cooling of the fuel cell can be suppressed. As a result, the performance degradation of the fuel cell is suppressed, and the startability of the fuel cell at a low temperature can be improved.

(Modification 3)
Further, when the cathode side space 16 is the sealed space 18, the entire cathode side space 16 may be the sealed space 18 as shown in FIG. FIG. 10 is a cross-sectional view schematically showing a cross section taken along line 7-7 of the fuel cell according to the modification. In the annual fuel cell according to the modified example 3, a part of the cathode side space 16 is a sealed space 18, so that cooling on the cathode side can be suppressed, and cooling can be appropriately adjusted for the entire fuel cell.

  For this purpose, the shape of the cathode side plate 401 may be set such that, for example, the convex portion 440 is connected to the adjacent convex portion 440 and the convex portion 446 as shown in FIG. FIG. 11A is a plan view schematically showing the cathode side plate 401 according to the modified example 3, and FIG. 11B shows the cathode side plate 401 in FIG. It is sectional drawing cut | disconnected. In the cathode side plate 401 according to the modified example 3, a part of the convex portion 440 is connected to the end portion 444 of the adjacent convex portion 440 and the convex portion 446 at the end portion 444. As a result, the portion surrounded by the convex portion 440 and the convex portion 446 forms the sealed space 18 together with the intermediate plate 200 when the separator 102 is assembled. That is, the concave portion 443 surrounded by the convex portion 440 and the convex portion 446 functions as a space forming portion. Here, by providing the cooling water supply opening and the cooling water discharge opening in the cathode side space 16 formed by the concave portion 442 not surrounded by the convex portion 440 and the convex portion 446 and the intermediate plate 200, A part of the cathode space 16 is set as a sealed space 18, and cooling water can be allowed to flow into the remaining space. Note that if the number and location of the convex portions 446 are changed, the number of sealed spaces 18 can be easily changed. As a result, the fuel cell 100 can be appropriately cooled.

(Modification 4)
Also, as shown in FIG. 12, the number of sealed spaces 18 may be increased at the end of the fuel cell and decreased at the center. FIG. 12 is a cross-sectional view schematically showing a cross section of the fuel cell 100 according to Modification 4 taken along line 7-7. Since heat moves from both sides of the fuel cell in the central portion of the fuel cell 100, heat is likely to be trapped, but at the end of the fuel cell 100, heat is transferred only from one side of the fuel cell, so It's hard to be trapped. Therefore, the temperature distribution in the fuel cell 100 is increased by increasing the number of sealed spaces 18 at the end of the fuel cell 100 to suppress the cooling of the fuel cell 100 and by decreasing the number at the center to promote the cooling of the fuel cell 100. And the reactivity depending on the location of the fuel cell 100 can be made uniform.

(Modification 5)
In this embodiment, the sealed space 18 is filled with a gas such as air. However, the sealed space 18 may be a vacuum space. Since the vacuum space has higher heat insulation than gas, for example, even when the outside air temperature is low, the heat is not easily transmitted to the inside of the fuel cell, and the fuel cell is not easily cooled. As a result, the startability of the fuel cell can be improved even when the outside air temperature is low. In order to make the sealed space 18 into a vacuum space, for example, the anode-side separator 300 and the intermediate plate 200 may be bonded under vacuum.

(Modification 6)
In the present embodiment, air is contained in the sealed space 18, but a cooling medium capable of supercooling such as sodium acetate trihydrate may be enclosed. Sodium acetate trihydrate is a substance having a melting point of 58 ° C., so it is solid at room temperature. However, when the temperature falls from a high temperature liquid state, it does not become solid even when the temperature falls below 58 ° C. It is easy to become. For example, the supercooled liquid undergoes a phase transition from a liquid to a solid by giving a shock, and generates heat. If the fuel cell is heated using this heat, the temperature of the fuel cell can be increased even when the outside air temperature is low, and the startability of the fuel cell can be improved. Sodium acetate trihydrate is produced by adding water at a ratio of 54 g of water to 82 g of sodium acetate.

  Hereinafter, the operation when sodium acetate trihydrate is sealed in the sealed space 18 will be described. In the operating state of the fuel cell 100, the temperature of the fuel cell 100 is higher than the melting point of sodium acetate trihydrate, 58 ° C., so that the sodium acetate trihydrate is liquid in the enclosed space 18. Here, when the operation of the fuel cell 100 is stopped, the temperature of the fuel cell 100 gradually decreases. However, even if the temperature falls below 58 ° C., sodium acetate trihydrate does not become a solid, It becomes a supercooled state. Next, when attempting to restart the fuel cell, when a shock is applied, sodium acetate trihydrate undergoes a phase transition from a liquid to a solid and generates heat. For example, when the temperature is low, the fuel cell 100 is also low in temperature, but the fuel cell 100 can be shocked, and the fuel cell 100 can be heated using heat generated during the phase transition. The electrochemical reaction of the fuel cell 100 is generally more reactive at higher temperatures. Therefore, if the fuel cell 100 is heated using the heat generated during the phase transition, the startability of the fuel cell 100 can be improved. it can. In addition, as what gives the shock to the fuel cell 100, for example, vibration when the door of an automobile is closed can be used. In this modification 5, sodium acetate trihydrate was used as the cooling medium capable of supercooling, but other cooling medium such as sodium thiosulfate pentahydrate having a melting point of 48 ° C., for example. May be used.

(Modification 7)
In this embodiment, the convex and concave structures of the anode side plate 300 and the cathode side plate are described as a so-called groove structure, but a rib structure as shown in FIGS. 13 to 15 may be used. FIG. 13 is a plan view of the anode side plate 302 according to Modification Example 7, and FIG. 14 is a plan view of the cathode side plate 402 according to Modification Example 7. FIG. 15 is a diagram in which the anode side plate 302 and the cathode side plate 402 of the fuel cell 100 according to Modification 7 are overlapped. Even if it is a rib structure, it is because it does not change that excessive cooling can be suppressed and heat insulation can be improved by providing the sealed space 18. As shown in FIG. 15, the convex portion 340 of the anode side plate 302 and the convex portion 440 of the cathode side plate 402 are positioned so as not to overlap each other when the anode side plate 302 and the cathode side plate 402 are overlapped. Each is formed.

(Modification 8)
In the present embodiment, the intermediate plate 200 is not formed with holes that constitute part of the various manifolds, but the intermediate plate 200 also has fuel gas supply holes that constitute part of the fuel gas supply manifold 110. 210, a fuel gas discharge hole 212 constituting a part of the fuel gas discharge manifold 112, an oxidation gas supply hole 220 constituting a part of the oxidation gas supply manifold 120, and a part of the oxidation gas discharge manifold 122. An oxidizing gas discharging hole 222, a cooling water supplying hole 230 constituting a part of the cooling water supply manifold 130, and a cooling water discharging hole 232 constituting a part of the cooling water discharge manifold 132 are formed. May be. Also in this modification, for example, at least a part of the anode-side space 12 can be used as the sealed space 18, and excessive cooling of the fuel cell can be suppressed.

(Modification 9)
In the present embodiment, for example, regarding the anode side plate 300, the height from the bottom of the concave portion 342 to the top of the convex portion 340 is described as being the same as the height from the bottom of the concave portion 342 to the outer peripheral portion 348, but from the bottom of the concave portion 342 The height to the outer peripheral portion may be, for example, approximately half the height from the bottom of the concave portion 342 to the top portion of the convex portion 340. In this case, by providing the seal portion between the intermediate plate 200 and the outer peripheral portion 348 of the anode side plate 348, the hermeticity can be maintained and the sealed space 18 can be formed, so that excessive cooling of the fuel cell can be suppressed. In addition, the height from the bottom of the recessed part 342 to an outer peripheral part should just be the height which can form the sealed space 18. FIG. Needless to say, the cathode-side plate 400 can have the same structure.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

The perspective view which shows typically the external appearance of the fuel cell which concerns on the Example of this invention. Explanatory drawing which shows the structure of a separator typically. The top view and sectional drawing which show an intermediate | middle plate typically. The top view and sectional drawing which show an anode side plate typically. The top view and sectional drawing which show a cathode side plate typically. The top view and sectional drawing which show typically the structure of a membrane electrode assembly. Sectional drawing which shows typically a part of cross section cut | disconnected by the 7-7 line | wire of the fuel cell shown in FIG. Sectional drawing which shows typically a part of cross section cut | disconnected by the 8-8 line | wire of the fuel cell shown in FIG. The top view and sectional drawing which show typically the anode side plate which concerns on the modification 1. As shown in FIG. Sectional drawing which shows typically the cross section cut | disconnected by the 7-7 line | wire of the fuel cell which concerns on the modification 3. FIG. The top view and sectional drawing which show typically the cathode side plate which concerns on the modification 3. As shown in FIG. Sectional drawing which shows typically the cross section cut | disconnected by the 7-7 line | wire of the fuel cell which concerns on the modification 4. FIG. FIG. 10 is a plan view of an anode side plate of a fuel cell according to Modification Example 7. FIG. 10 is a plan view of a cathode side plate of a fuel cell according to Modification Example 7. The figure which accumulated the anode side plate and cathode side plate of the fuel cell which concerns on the modification 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel gas buffer 12 ... Anode side space 14 ... Oxidation gas buffer 16 ... Cathode side space 18 ... Sealed space 100 ... Fuel cell 102 ... Separator 104 ... Membrane electrode assembly 110 ... Fuel gas supply manifold 112 ... Fuel gas discharge manifold 120 ... oxidizing gas supply manifold 122 ... oxidizing gas discharge manifold 130 ... cooling water supply manifold 132 ... cooling water discharge manifold 200 ... intermediate plates 300, 301, 302 ... anode side plate 340 ... convex part 342 ... concave part 343 ... concave part 344 ... end 346 ... convex part 348 ... outer peripheral part 349 ... concave part 400, 401, 402 ... cathode side plate 440 ... convex part 442 ... concave part 443 ... concave part 446 ... convex part 448 ... outer peripheral part 449 ... concave part 500 ... resin Frame 210, 310, 410, 5 0 ... Fuel gas supply holes 212, 312, 412, 512 ... Fuel gas discharge holes 220, 320, 420, 520 ... Oxidation gas supply holes 222, 322, 422, 522 ... Oxide gas discharge holes 230, 330, 430, 530 ... cooling water supply hole 232, 332, 432, 532 ... cooling water discharge hole 534 ... cooling water supply opening 540 ... electrolyte membrane 542 ... porous body 544 ... for electrolyte membrane insertion Aperture

Claims (10)

A fuel cell in which separators and membrane electrode assemblies are alternately stacked,
The separator is
A first plate;
A second plate disposed on one surface side of the first plate, wherein the first plate is convex toward the first plate, and a plurality of convex portions are in contact with the first plate; A second plate comprising a space forming portion for forming at least one sealed space with the first plate;
A third plate disposed on the other surface side of the first plate and sandwiching the first plate together with the second plate, wherein the top plate is convex toward the first plate side, A third plate provided with a plurality of convex portions formed in a place in contact with the first plate and not overlapping with the convex portions of the second plate;
A fuel cell comprising: The fuel cell according to claim 1, wherein
The said space formation part is a fuel cell which is formed in the approximate center of the said 2nd plate, and is a concave part which has the said convex part. The fuel cell according to claim 1, wherein
The space forming portion connects the both ends of the first convex portion of the second plate and the both ends of the second convex portion adjacent to the first convex portion by a third convex portion. A fuel cell, which is a recess formed by being surrounded by a third protrusion from the protrusion. The fuel cell according to any one of claims 1 to 3, further comprising:
The fuel cell, wherein the third plate includes a space forming portion for forming at least one sealed space between the third plate and the first plate. The fuel cell according to claim 4, wherein
The said space formation part is a fuel cell which is formed in the approximate center of the said 3rd plate, and is a concave part which has the said convex part. The fuel cell according to claim 4, wherein
The space forming portion connects the both ends of the first convex portion of the third plate and the both ends of the second convex portion adjacent to the first convex portion by the third convex portion. A fuel cell, which is a recess formed by being surrounded by a third protrusion from the protrusion. The fuel cell according to claim 3 or 6, wherein
The fuel cell in which the number of the sealed spaces is larger as the separator is closer to the end of the fuel cell and is smaller as the separator is closer to the center of the fuel cell. The fuel cell according to any one of claims 1 to 7, wherein
The sealed space is a fuel cell filled with a gas or a vacuum space. The fuel cell according to any one of claims 1 to 7, wherein
A fuel cell in which a cooling medium capable of overcooling is enclosed in at least a part of the sealed space.   10. The fuel cell according to claim 9, wherein the supercoolable cooling medium is sodium acetate.

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