JP2007294243A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformalize in-plane distribution of a fastening force acting on the surface of each of cells stacked to constitute a cell stack. <P>SOLUTION: In the fuel cell, a cell is formed by laminating a membrane-electrode assembly and separators 20 and a cell stack is formed by laminating a plurality of cells. A plate-like tension member 29 is at least partly housed in a concave part 26 formed at each edge part of the separator 20 and is utilized to bias a load in a lamination direction on the cell stack. The concave part 26 is formed between corner parts 25 formed so as to protrude from four corners of the separator 20 in a width direction. An outer face 29a of the tension member 29 and an outer face 25a of the corner part 25 are preferred to be on the same plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell. More specifically, the present invention relates to an improved configuration for fastening a plurality of stacked separators and the like.

In general, a fuel cell (for example, a polymer electrolyte fuel cell) is configured by stacking a plurality of cells each having a membrane-electrode assembly (MEA) sandwiched between separators. In this case, as a structural example for fastening the cell stack in the stacking direction, there is a structure in which both ends of the stack are sandwiched between support plates, and both support plates are fastened with a plurality of bolts. In this case, a structure is also proposed in which a bolt is arranged in a recessed portion of the edge of the separator (see, for example, Patent Document 1).
JP 2004-185940 A

  However, in the case of the conventional structure in which the cell stack is tightened using a plurality of bolts as described above, there is a problem that the fastening load acting on the surface of each stacked cell tends to be uneven.

  Further, as a fuel cell as described above, there is also disclosed a configuration in which the entire manifold is accommodated in a portion of the separator that protrudes from the rectangular region, but this may cause another problem. That is, with such a configuration, the communication path (communication path) for communicating the manifold and the power generation region in which the MEA is provided becomes complicated because it requires a part to change the flow direction, and Since the communication path length becomes long, flow path resistance is caused (see FIG. 3).

  In view of this, the present invention provides a structure in which the in-plane distribution of the fastening force acting on the surfaces of the cells that are stacked to form the cell stack can be made uniform, or the manifold and the power generation region communicate with each other. An object of the present invention is to provide a fuel cell provided with at least one of the structures which can avoid the complication of the structure of the communication passage and reduce the flow resistance.

  In order to solve this problem, the present invention provides a fuel cell in which a cell is formed by stacking a membrane-electrode assembly and a separator, and a cell stack is formed by stacking a plurality of the cells. A plate-like tension member that is at least partially accommodated in a recess formed on the edge is disposed, and a load in the stacking direction is applied to the cell stack using the tension member.

  In the case of a structure in which a compressive load is applied using bolts as in the prior art, for example, a structure in which the four corners of the supporting plate facing each other are tightened with, for example, four bolts, the inventor balances the compressive load between the bolts. Because it is difficult to remove, it is easy to cause unevenness of the surface pressure in the cell stack due to the unevenness of the balance, and the configuration that can solve such a problem paying attention to the fact that the fastening load acting on the surface of each cell tends to be uneven It came to know. The structure for applying a load in the present invention based on such knowledge has a configuration in which the opposing support plate and the support plate are connected by, for example, a pair of plate-like tension members, that is, a configuration having higher rigidity than before. ing. For this reason, when a compressive load is applied between the support plates using such a tension member, it is easy to balance the load, and the fastening load acting in the plane of each stacked cell becomes non-uniform. It is easy to suppress.

  In the fuel cell of the present invention, the recess is formed between corner portions formed so as to protrude from the four corners of the separator in the width direction of the separator. By making the four corners of the separator project in the width direction, part or all of the tension member can be accommodated in a space (concave portion) formed between the corner portions.

  Furthermore, in this fuel cell, it is preferable that the outer surface of the tension member and the outer surface of the corner portion are flush with each other. In this case, the tension member is completely accommodated in each space (recessed portion), and the entire shape of the cell stack including the tension member can be, for example, a rectangular shape. In such a case, since there is no portion protruding from the outer surface, the fuel cell can be easily accommodated in a moving body or the like and can be handled easily.

  In the fuel cell, a manifold for each fluid of the reaction gas and the cooling water is provided along an edge of a portion of the separator that protrudes from a region sandwiched between the tension members. It is preferable that at least a portion facing the membrane-electrode assembly in the flow path of the reactive gas formed in is located in a region sandwiched between the tension members. The part of the separator where the flow path for various fluids (fuel gas, oxidizing gas, etc.) is formed is a part that particularly contributes to power generation. In contrast, according to the present invention, the part that contributes to power generation is fastened. The force can be made uniform.

  Furthermore, the present inventor who also studied the shape of the separator and the arrangement of the manifold has come to know a technique that can effectively suppress the complication of the communication passage and the increase in the flow resistance. The present invention is also based on such knowledge, and in a fuel cell in which a cell is configured by stacking a membrane-electrode assembly and a separator, and a cell stack is configured by stacking a plurality of the cells, the separator includes: A manifold having a substantially rectangular area and a protruding area formed so as to protrude from the rectangular area in the direction of the surface of the separator. The portion is located, at least the other part is located in the rectangular region.

  In the case of such a fuel cell, the portion of the separator that protrudes from the rectangular region (the protruding region) does not accommodate any of the manifolds, but only a part of the manifold. For this reason, it is possible to simplify the configuration of the communication path (communication path) between the power generation region and the manifold and shorten the flow path length of the communication path.

  According to the present invention, it is possible to equalize the in-plane distribution of the fastening force acting on the surfaces of the cells that are stacked to form the cell stack, or to connect the manifold and the power generation region. At least one of the problems of avoiding complication of the configuration and reducing the channel resistance can be solved.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 4 show an embodiment of a fuel cell system according to the present invention. The fuel cell system according to the present embodiment constitutes a cell by laminating a membrane-electrode assembly and a separator, and constitutes a cell stack by laminating a plurality of the cells. In such a fuel cell, a plate-like tension member (hereinafter also referred to as a tension plate) 29 in which at least a part of the cross section fits in a recess 26 formed on the edge of the separator, and a cell stack using the tension plate 29 A load in the stacking direction is applied to the film.

  In the embodiments described below, first, a schematic configuration of the cells 2 constituting the fuel cell 1 will be described, and then the fuel cell 1 configured by stacking a plurality of cells 2 will be described.

  FIG. 1 shows a schematic configuration of a cell 2 of a fuel cell 1 in the present embodiment. The fuel cell 1 constituted by such a cell 2 can be used as, for example, an in-vehicle power generation system of a fuel cell vehicle (FCHV), but is not limited to this, and various types of movement are possible. It can also be used as a power generation system mounted on a body (such as a ship or an airplane) or a robot that can run on its own, or as a stationary fuel cell.

  The cell 2 includes a membrane-electrode assembly (hereinafter referred to as MEA; Membrane Electrode Assembly) 30 and a pair of separators 20a and 20b that sandwich the MEA 30 (see FIG. 1). The MEA 30 and the separators 20a and 20b are formed in a substantially rectangular plate shape. Further, the MEA 30 is formed so that its outer shape is smaller than the outer shape of each separator 20a, 20b. Furthermore, the MEA 30 and the separators 20a and 20b are molded together with the first seal member 13a and the second seal member 13b at the peripheral portion between them.

  The MEA 30 includes a polymer electrolyte membrane (hereinafter also simply referred to as an electrolyte membrane) 31 made of an ion exchange membrane made of a polymer material, and a pair of electrodes 32a and 32b (anode and cathode) sandwiching the electrolyte membrane 31 from both sides. Has been. Among these, the electrolyte membrane 31 is formed to be slightly larger than the electrodes 32a and 32b. The electrodes 32a and 32b are joined to the electrolyte membrane 31 by, for example, a hot press method while leaving the peripheral edge portion 33.

  The electrodes 32a and 32b constituting the MEA 30 are made of, for example, a porous carbon material (diffusion layer) carrying a catalyst such as platinum attached to the surface thereof. One electrode (anode) 32a is supplied with hydrogen gas as a fuel gas, and the other electrode (cathode) 32b is supplied with an oxidizing gas such as air or an oxidant, and these two gases cause an electrochemical reaction in the MEA 30. As a result, the electromotive force of the cell 2 can be obtained.

  Separator 20a, 20b is comprised with the gas-impermeable electroconductive material. Examples of the conductive material include carbon and a hard resin having conductivity, and metals such as aluminum and stainless steel. The base material of the separators 20a and 20b of this embodiment is formed of a plate-like metal (metal separator), and a film (for example, gold plating) having excellent corrosion resistance is provided on the surface of the base material on the electrodes 32a and 32b side. Is formed).

  Further, a groove-like flow path constituted by a plurality of concave portions is formed on both surfaces of the separators 20a and 20b. These flow paths can be formed by press molding in the case of the separators 20a and 20b of the present embodiment in which the base material is formed of, for example, a plate-like metal. The groove-shaped flow path formed in this way constitutes a gas flow path 34 for oxidizing gas, a gas flow path 35 for hydrogen gas, or a cooling water flow path 36. More specifically, a plurality of gas passages 35 for hydrogen gas are formed on the inner surface on the electrode 32a side of the separator 20a, and a plurality of cooling water passages 36 are formed on the back surface (outer surface). (See FIG. 1). Similarly, a plurality of gas channels 34 for oxidizing gas are formed on the inner surface of the separator 20b on the electrode 32b side, and a plurality of cooling water channels 36 are formed on the back surface (outer surface) (FIG. 1). reference). For example, in the case of this embodiment, the gas flow path 34 and the gas flow path 35 in the cell 2 are formed to be parallel to each other. Further, in the present embodiment, regarding the two adjacent cells 2 and 2, when the outer surface of the separator 20a of one cell 2 and the outer surface of the separator 20b of the cell 2 adjacent thereto are attached together, The water flow path 36 is integrated to form a flow path having a rectangular cross section (see FIG. 1). In addition, the separator 20a and the separator 20b of the adjacent cells 2 and 2 are molded with a sealing member at the peripheral portion between them.

  Further, in the vicinity of the longitudinal ends of the separators 20a and 20b (in the case of this embodiment, in the vicinity of one end shown on the left side in FIG. 1), the manifold 15a on the inlet side of the oxidizing gas, hydrogen gas An outlet side manifold 16b and a cooling water outlet side manifold 17b are formed. For example, in the case of this embodiment, these manifolds 15a, 16b, and 17b are formed by substantially rectangular or trapezoidal through holes provided in the separators 20a and 20b (see FIG. 1). Further, an oxidant gas outlet side manifold 15b, a hydrogen gas inlet side manifold 16a, and a cooling water inlet side manifold 17a are formed at opposite ends of the separators 20a and 20b. In the case of this embodiment, these manifolds 15b, 16a, and 17a are also formed by substantially rectangular or trapezoidal through holes (see FIG. 1).

  Among the manifolds as described above, the inlet side manifold 16a and the outlet side manifold 16b for the hydrogen gas in the separator 20a are connected to the inlet side communication passage 61 and the outlet side communication passage 62 formed in the separator 20a in a groove shape. Each communicates with a gas flow path 35 of hydrogen gas. Similarly, the inlet side manifold 15a and the outlet side manifold 15b for the oxidizing gas in the separator 20b are oxidized via the inlet side communication passage 63 and the outlet side communication passage 64 formed in the separator 20b in a groove shape. The gas communicates with the gas flow path 34 (see FIG. 1). Further, the inlet side manifold 17a and the outlet side manifold 17b of the cooling water in each separator 20a, 20b are connected to each separator 20a, 20b through an inlet side communication passage 65 and an outlet side communication passage 66 formed in a groove shape. Each communicates with the cooling water passage 36. With the configuration of the separators 20a and 20b as described above, the cell 2 is supplied with oxidizing gas, hydrogen gas, and cooling water. As a specific example, for example, hydrogen gas passes through the communication passage 61 from the inlet side manifold 16a of the separator 20a and flows into the gas flow path 35, and is supplied to the power generation of the MEA 30. It passes through and flows out to the outlet side manifold 16b.

  The first seal member 13a and the second seal member 13b are both frame-shaped members that are formed in substantially the same shape (see FIG. 1). Among these, the first seal member 13a is provided between the MEA 30 and the separator 20a, and more specifically, the peripheral portion 33 of the electrolyte membrane 31, and the portion of the separator 20a around the gas flow path 35. Between the two. The second seal member 13b is provided between the MEA 30 and the separator 20b. More specifically, the second seal member 13b is formed between the peripheral portion 33 of the electrolyte membrane 31 and a portion of the separator 20b around the gas flow path 34. It is provided so as to be interposed therebetween.

  Further, a frame-shaped third seal member 13c is provided between the separators 20b and 20a of the adjacent cells 2 and 2 (see FIG. 1). The third seal member 13c is provided so as to be interposed between a portion around the cooling water passage 36 in the separator 20b and a portion around the cooling water passage 36 in the separator 20a, and seals between them. It is. By the way, in the cell 2 of the present embodiment, among the various fluid passages (34 to 36, 15a, 15b, 16a, 16b, 17a, 17b, 61-66) in the separators 20a and 20b, The manifolds 15a, 16a, 17a and the outlet side manifolds 15b, 16b, 17b are passages located outside the first seal member 13a, the second seal member 13b, and the third seal member 13c (see FIG. 1). .

  A plurality of the cells 2 configured as described above are stacked to constitute a stack (cell stack) 3. In addition, the stack 3 formed by stacking the cells 2 in this manner is tightened by applying a compressive load in the stacking direction using fastening means or the like. Here, in the present embodiment, both ends of the stack 3 are sandwiched between the support plates 8 and 9 and a plate-like tension plate 29 is disposed so as to connect the opposing support plates 8 and 9 together. The load is applied to the stack 3 in the stacking direction (see FIG. 2).

  The advantages of the fuel cell 1 of this embodiment that employs such a plate-like tension member (tension plate) 29 will be described as follows. That is, if the structure is such that a compressive load is applied using bolts as in the prior art, for example, the four corners of the opposing support plates 8 and 9 are tightened with four bolts, it is difficult to balance the compressive load between the bolts. However, in this embodiment, the tension plate 29 is disposed so as to connect the supporting plates 8 and 9 and the supporting plates 8 and 9 that face each other. The tension plate 29 is also used to apply a compressive load in the stacking direction. In this case, it is possible to construct a fastening means having a higher rigidity than before, and when a compression load is applied between the support plates 8 and 9 using the tension plate 29, it is easy to balance the load. There is an advantage that it is easy to suppress non-uniform fastening loads acting on the surfaces of the stacked cells 2.

  Furthermore, in this embodiment, it is set as the shape in which the recessed part 26 which can accommodate at least one part of the tension plate 29 mentioned above was formed regarding the edge of the separator 20 (refer FIG. 2). In such a case, since at least a part of the tension plate 29 is accommodated in the concave portion 26, it is possible to form the stack 3 with less surface irregularities in a state where the fastening means are integrated.

  Here, such concave portions 26 are formed by using, for example, a corner portion 25 so as to protrude from the four corners of the separator 20 toward the outside of the separator 20 and using a space sandwiched between the two corner portions 25. (See FIG. 2). Thus, according to the method of forming the concave portion 26 by projecting a part of the separator 20, there is an advantage that it can be easily applied to the separator 20 that has already been designed and put into practical use. That is, since the shape or structure is such that the corner portion 25 is added to the outside of the conventional separator 20, no major design change is required, and there is no need to change or modify the fluid flow path.

  For example, in this embodiment, the corner portion 25 is formed so as to protrude from the four corners of the separator 20 in the width direction of the separator 20 (see FIGS. 1 and 2). The width direction here may differ in the shape of the separator 20 and the like, but for example, the direction in which each fluid flows (the direction from one end manifold 15a, 16b, 17b to the other end manifold 15b, 16a, 17a) is the longitudinal direction. In the case of the separator 20 of the present embodiment that coincides with the above, it is the short direction, that is, both the left and right directions of the fluid flow. However, in the present embodiment, the width direction coincides with the short direction of the separator 20, but this is only an example, and it does not need to coincide with the short direction.

  Further, the shape of the corner portion 25 as described above is not particularly limited. For example, in this embodiment, the side that forms the recess 26 is a hypotenuse, and the trapezoid shape becomes narrower as it protrudes in the width direction. (See FIGS. 1 and 2). In such a case, each corner portion 25 becomes wider at the base, which can be advantageous in terms of strength (for example, bending strength). In the present embodiment, the corner portions 25 at the four corners are formed in the same shape that is line-symmetric or point-symmetric with respect to each other. However, the shapes and sizes of the corner portions 25 may be different from each other. For example, the size and shape of the corner portion 25 and the size and shape of the concave portion 26 can be made different on the left and right sides of the fluid flow channel (the gas flow channels 34 and 35 and the cooling water flow channel 36). .

  Furthermore, in this embodiment, the outer surface 29a of the tension plate 29 and the outer surface 25a of each corner portion 25 are flush with each other (see FIG. 2). In such a case, since the tension plate 29 can be completely accommodated in the concave portions 26 formed on both sides in the width direction, the cross-sectional shape of the stack 3 including the tension plate 29 is rectangular or The approximate shape can be used, and the overall stack shape can be, for example, a rectangular parallelepiped or a shape approximate to this. In such a case, there is no portion protruding from the outer surface or outline of the stack 3, so that it is preferable in that the fuel cell 1 is easy to be accommodated in a moving body or the like and easy to handle.

  In addition, in the present embodiment, for each fluid of the reaction gas (oxidizing gas and hydrogen gas) and cooling water along the edge of the portion of the separator 20 that protrudes from the region sandwiched by the tension plate 29. Manifolds 15a, 15b, 16a, 16b, 17a, and 17b are provided (see FIG. 2). Further, at least a portion facing the MEA 30 in the reaction gas flow path (oxidation gas flow path 34, hydrogen gas flow path 35) formed in the cell 2 is sandwiched between the tension plates 29. It is located within the region (see FIG. 2). The part of the separator 20 in which the flow path for hydrogen gas or oxidizing gas is formed is a part that particularly contributes to power generation. In this way, the part is included in the predetermined region in this way. According to the fuel cell 1, it is possible to equalize the fastening force for the portion that contributes to the power generation.

  Here, the shape of the separator 20 and the arrangement of the manifolds 15a to 17b are preferably as follows. That is, when the separator 20 includes a substantially rectangular region and a protruding region (in this embodiment, for example, the corner portion 25) formed so as to protrude from the rectangular region in the surface direction of the separator 20 The manifolds 15a to 17b that are partially located in the corner portion (protruding region) 25 are at least partially located in a rectangular region (see FIG. 2).

  For example, as seen in a conventional fuel cell, it is not preferable in terms of configuration if the entire manifold is accommodated in a portion of the separator 20 that protrudes from the rectangular region (the protruding region) (see FIG. 3). That is, a communication passage (indicated by reference numeral 64 ′ in FIG. 3) for communicating the manifold (indicated by reference numeral 15 ′ in FIG. 3) 34 and the power generation region provided with the MEA has a flow direction. Since a part to be converted is required, the complication is complicated, and the length of the communication passage 64 ′ becomes long, which may lead to flow path resistance (see FIG. 3).

  On the other hand, in the case of the fuel cell 1 according to the present embodiment, the protruding region (corner portion 25) that protrudes from the rectangular region of the separator 20 does not contain, for example, the entire manifold 15b. Only a part. For this reason, it is possible to simplify the configuration of the communication passage (for example, the communication passage 64) between the power generation region and the manifold 15b and shorten the flow path length of the communication passage (see FIG. 2). The same applies to other manifolds and communication passages.

  Here, the fuel cell 1 of the present embodiment having the above-described configuration has a stack structure in which cells (single cells) 2 are stacked. The fuel cell 1 has a stack 3 in which a plurality of cells 2 are stacked. A structure in which current collecting plates 4 and 5 with output terminals (not shown), insulating plates 6 and 7 and end plates 8 and 9 are sequentially arranged outside the cells 2 and 2 located at both ends of the stack 3, respectively. It has become. In addition, the fuel cell 1 includes, for example, a stacking direction of the cells 2 by fixing a tension plate 29 arranged so as to bridge between both end plates 8 and 9 to each end plate 8 and 9 with a bolt 27 or the like. Is in a state where a predetermined fastening force is applied.

  Alternatively, a predetermined fastening force (compression force) may be applied using an elastic member (biasing means) 11 such as a spring. As an example, the fuel cell 1 shown in FIG. 4 includes a stack 3, a first current collector plate 4, a second current collector plate 5, a first insulator 6, a second insulator 7, and a first It has a pressure plate (support plate) 8, a second pressure plate (support plate) 9, a pressure plate 10, an elastic member 11, a bolt 27, a nut 28, and a tension plate 29 (see FIG. 4). The stack 3 includes a plurality of stacked cells 2, a first current collector plate 4, a first insulator 6, a second current collector plate 5, and a second insulator 7 (see FIG. 4).

  The first current collector plate 4 is a terminal for directly connecting to one end in the stacking direction of the cells 2, and the second current collector plate 5 is electrically connected to the other end in the stacking direction of the cells 2. This is a terminal for direct connection. The first insulator 6 is an insulator that insulates between the first current collector plate 4 and the first pressure plate 8, and the second insulator 7 is composed of the second current collector plate 5 and the pressure plate 10. It is an insulator which electrically insulates between.

  The first pressure plate 8 is a plate that receives a compressive load from the stack 3 side, and has a plurality of holes (not shown) that are screwed into the bolts 27 at the side ends of the first pressure plate 8. . On the outer surface of the first pressure plate 8, for example, an oxidizing gas supply port 8a and an exhaust port 8b, a fuel gas supply port 8c and an exhaust port 8d are provided.

  The second pressure plate 9 is a plate arranged at a distance from the pressure plate 10 and has a plurality of holes (not shown) through which the rod portion 29a of the tension plate 29 passes. The second pressure plate 9 receives a pressing force by the elastic member 11.

  The pressure plate 10 is a plate that presses the stack 3 against the first pressure plate 8 side by the pressing force of the elastic member 11.

  The elastic member 11 is an elastic body for applying a pressing force to the stack 3 via the pressure plate 10, and a plurality of (for example, four) elastic members 11 are arranged between the second pressure plate 9 and the pressure plate 10. . As such an elastic member 11, a compression coil spring, a disc spring, etc. can be used, for example.

  The tension plate 29 is provided as a flat plate for fastening the first pressure plate 8 and the second pressure plate 9. The tension plate 29 shown here is arranged in the stacking direction outside the stack 3, and has a plurality of holes (not shown) for fastening to the side ends of the first pressure plate 8 with bolts 27. And a plurality of rod portions 29a to which rods penetrating through holes (not shown) of the second pressure plate 9 are welded. For example, two tension plates 29 are paired and arranged to face each other with the stack 3 interposed therebetween (see FIG. 4).

  The bolt 27 is an attachment member for attaching the tension plate 29 to the first pressure plate 8, passes through a hole (not shown) of the tension plate 29, and is provided at a side end of the first pressure plate 8 (see FIG. (Not shown). The nut 28 is a member for receiving the second pressure plate 9 pressed by the elastic member 11, and is screwed at the tip of the rod portion 29 a penetrating a hole (not shown) of the second pressure plate 9. .

  The stack 3 is provided with a cell monitor (not shown) for measuring the voltage of the cell 2 in order to monitor and control the operation state of the fuel cell 1. In the fuel cell 1, control of output and the like based on the voltage measurement result is performed. In FIG. 4, two current collecting plates are illustrated (current collecting plates indicated by reference numerals 4 and 5). In order to perform voltage monitoring by such a cell monitor, a predetermined value along the cell stacking direction is used. It is desirable to provide further output terminals (and current collector plates) at a plurality of locations in advance so that they can be switched to these different output terminals while monitoring the cell voltage.

  As described above, according to the fuel cell 1 of the present embodiment described so far, the in-plane distribution of the fastening force acting on the surfaces of the cells 2 that are stacked to form the stack 3 is uniformized (or homogenized). It is possible. That is, in the fuel cell 1 described above, since the first pressure plate 8 and the second pressure plate 9 are fastened by the plate-like tension member (tension plate) 29, the rigidity against bending and the bending rigidity are excellent. There is an advantage that resistance to twisting is large. For this reason, since a highly rigid fastening means can be comprised, the balance of the compression load which acts between the end plates (support plates) 8 and 9 is balanced, and the fastening load which acts on the surface of each laminated cell 2 is uniform. It is possible to

  Thus, the following can be mentioned as an advantage when the load which acts in the surface of each cell 2 is made uniform. That is, for example, in a solid polymer electrolyte fuel cell, a reaction for converting hydrogen into hydrogen ions and electrons is performed on the anode side, and the hydrogen ions move to the cathode side through the electrolyte membrane, and oxygen and hydrogen ions on the cathode side. Then, a reaction for generating water from the electrons (electrons generated at the anode of the adjacent MEA 30 pass through the separator 20) is performed. In order for such an electrochemical reaction to be normally performed, it is necessary that the fastening load of the stack 3 is uniform over the entire cross section of the electrode portion of the stack 3 and does not vary greatly. Further, since heat is generated in the water generation reaction at the cathode, a flow path through which a cooling medium (usually cooling water) flows is formed between the separators 20 in each cell 2 or for each of the plurality of cells 2. The fuel cell 1 is cooled. Therefore, the environmental temperature of the fuel cell 1 repeatedly changes between the ambient temperature when the operation is stopped (for example, 20 ° C.) and the cooling medium temperature when the operation is performed (for example, about 80 ° C.). To do. The load can also be changed by the creep phenomenon of the film or electrode. In such a situation, according to the fuel cell 1 described in the present embodiment, the in-cell load can be made more uniform, so that the electrochemical reaction in the battery can be continued in a more normal state. Is advantageous.

  In addition to the above, in the fuel cell 1 of the present embodiment, the outer surface 29a of the tension plate 29 and the outer surface 25a of each corner portion 25 are flush with each other. It can be in a state (see FIG. 2). In addition, this makes it possible to eliminate the outer surface of the stack 3 or the portion protruding from the outer shell, and to make the fuel cell 1 easy to handle.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, each fluid channel is exemplified as a straight channel (see FIG. 1). However, the present invention is not limited to this, and the present invention can be applied to a serpentine channel, for example. .

  In the present embodiment, a tension plate is illustrated as a good example of the plate-like tension member 29, but the plate-like tension member 29 is not limited to such a plate-like member. For example, even if the member has a rectangular frame with diagonal crossings and is not approximately plate-shaped, it can be used as the tension member 29 in the same way as the tension plate as long as it has the same level of rigidity as the plate shape. Is possible.

It is a disassembled perspective view which shows one Embodiment of this invention, and decomposes | disassembles and shows the cell of the fuel cell in this embodiment. It is a schematic sectional drawing which shows an example of the external shape of a separator, and an example of the tension plate stored in the recessed part of the said separator. It is a reference drawing which shows the said structure part in case the whole manifold is accommodated in the part which protruded from the rectangular area | region among the separators. It is a side view of the fuel cell which shows an example of the fastening means comprised by a tension plate etc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Cell, 3 ... Stack (cell stack), 20 ... Separator, 25 ... Corner part (extrusion area | region), 25a ... Outer surface of a corner part, 26 ... Recessed part, 29 ... Tension plate (tension member), 29a ... outer surface of tension plate (tension member), 30 ... MEA (membrane-electrode assembly)

Claims (5)

In a fuel cell in which a cell is configured by stacking a membrane-electrode assembly and a separator, and a cell stack is configured by stacking a plurality of the cells,
A plate-like tension member that is at least partially accommodated in a recess formed on an edge of the separator is disposed, and a load in the stacking direction is applied to the cell stack using the tension member. Fuel cell.   2. The fuel cell according to claim 1, wherein the concave portion is formed between corner portions formed so as to protrude from the four corners of the separator in the width direction of the separator.   The fuel cell according to claim 1, wherein an outer surface of the tension member and an outer surface of the corner portion are flush with each other.   A manifold for each fluid of reaction gas and cooling water is provided along an edge of a portion of the separator that protrudes from a region sandwiched by the tension member, and the reaction gas formed in the cell 4. The fuel cell according to claim 1, wherein at least a portion of the flow path facing the membrane-electrode assembly is located in a region sandwiched between the tension members. 5. . In a fuel cell in which a cell is configured by stacking a membrane-electrode assembly and a separator, and a cell stack is configured by stacking a plurality of the cells,
The separator includes a substantially rectangular region and a protruding region formed so as to protrude from the rectangular region in the surface direction of the separator,
A manifold for each fluid of reaction gas and cooling water, a part of which is located in the protruding area, at least the other part of which is located in the rectangular area battery.

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