power generation unit

Abstract

The first separator has a plurality of first protrusions provided along an outer edge portion of the membrane electrode structure and protruding toward an opposite side of the first surface, and the second separator has a plurality of second protrusions provided along the outer edge portion of the membrane electrode structure and protruding toward an opposite side of the second surface. The plurality of first protrusions have an elongated shape extending in a plurality of first center lines parallel to each other, respectively, with a first width orthogonal to the plurality of first center lines, and the plurality of second protrusions have an elongated shape extending in a plurality of second center lines parallel to each other, respectively, with a second width orthogonal to the plurality of second center lines. In a plan view observed from a direction perpendicular to the first surface, the first center lines and the second center lines are substantially parallel to each other, and the first width is narrower than the second width.

Description

Technical Field

[0001] This invention relates to a power generation unit for a fuel cell. Background Technology

[0002] In recent years, fuel cells that help improve energy efficiency have been researched and developed to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. As a technology related to power generation units used in such fuel cells, a power generation unit is known to have multiple protrusions protruding towards the side opposite to the side where the electrolyte membrane is disposed, along the periphery of the separator along its length (see, for example, Patent Document 1). In the power generation unit described in Patent Document 1, multiple first protrusions protruding from a first separator opposite to one surface of the electrolyte membrane and multiple second protrusions protruding from a second separator opposite to the other surface of the electrolyte membrane intersect at a predetermined angle and abut against each other.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 7238761 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, as described in the aforementioned Patent Document 1, when the power generation unit is configured with a plurality of first protrusions and a plurality of second protrusions intersecting at a predetermined angle and abutting against each other, it is impossible to ensure that the protrusions have sufficient contact area with each other, which may lead to deformation of the partition.

[0008] Technical solutions for solving technical problems

[0009] According to one aspect of the present invention, a power generation unit includes a membrane electrode structure, a first partition, and a second partition. The membrane electrode structure is constructed by integrating a membrane electrode assembly and a frame component. The membrane electrode assembly has an electrolyte membrane and first and second electrodes respectively disposed on two surfaces of the electrolyte membrane. The frame component supports the outer edge of the membrane electrode assembly. The first and second partitions are respectively disposed opposite to the first surface and the second surface opposite to the first surface of the membrane electrode structure, forming gas flow paths for the flow of reactant gases between them and the first and second electrodes. The first partition has a plurality of first protrusions disposed along the outer edge of the membrane electrode structure and protruding to the opposite side of the first surface. The second partition has a plurality of second protrusions disposed along the outer edge of the membrane electrode structure and protruding to the opposite side of the second surface. The plurality of first protrusions are elongated shapes extending along a plurality of mutually parallel first center lines, each with a first width orthogonal to the plurality of first center lines. The plurality of second protrusions are elongated shapes extending along a plurality of mutually parallel second center lines, each with a second width orthogonal to the plurality of second center lines. In a top view viewed from a direction perpendicular to the first surface, the first center lines and the second center lines are substantially parallel to each other, and the first width is narrower than the second width.

[0010] Invention Effects

[0011] According to the present invention, deformation of a pair of partitions whose protrusions are in contact with each other can be suppressed. Attached Figure Description

[0012] Figure 1 This is a perspective view that schematically represents the overall structure of a fuel cell stack having the power generation unit according to an embodiment of the present invention.

[0013] Figure 2 yes Figure 1 Section II-II.

[0014] Figure 3 This is a perspective view showing the schematic structure of the integrated electrode assembly constituting the power generation unit according to the embodiments of the present invention.

[0015] Figure 4 This is a front view showing the schematic structure of the partition that constitutes the power generation unit according to the embodiments of the present invention.

[0016] Figure 5A It is in the front surface of the partition Figure 4 An enlarged view of the V-shaped part.

[0017] Figure 5B It is the rear surface of the partition and Figure 5A Enlarged view of the corresponding part.

[0018] Figure 6 yes Figure 5A Section VI-VI.

[0019] Figure 7 yes Figure 5A Section VII-VII.

[0020] Figure 8 yes Figure 5A Section VIII-VIII.

[0021] Figure 9 This is a diagram used to illustrate the positional relationship between the main part of the partition and the integrated electrode assembly.

[0022] Figure 10 yes Figure 5A XX cross-sectional view.

[0023] Figure 11 Is with Figure 5A Front view of the main parts of the different partitions. Detailed Implementation

[0024] Below, refer to Figures 1 to 11 Embodiments of the present invention will be described. The power generation unit involved in the embodiments of the present invention is a power generation body constituting a fuel cell stack. The fuel cell is, for example, mounted in a vehicle to generate electricity for driving the vehicle. First, the overall structure of the fuel cell stack will be described in general terms. Sometimes the fuel cell stack is simply referred to as a fuel cell.

[0025] Figure 1 This is a perspective view roughly representing the overall structure of the fuel cell stack 100. For ease of explanation, as shown in the figure, the three mutually orthogonal axes are defined as the front-rear, left-right, and up-down directions, and the structure of each part will be explained according to this definition. These directions are not necessarily the same as the front-rear, left-right, and up-down directions of a vehicle. That is, Figure 1 The front-back direction can be the front-back direction of the vehicle, the left-right direction, or the up-down direction.

[0026] like Figure 1 As shown, the fuel cell stack 100 has a unit stack 101 and end units 102, and is generally rectangular in shape. The unit stack 101 is constructed by stacking multiple power generation units 1 in the front-to-back direction. The end units 102 are disposed at both ends of the unit stack 101 in the front-to-back direction. A generally box-shaped shell with open front and rear surfaces is disposed around the unit stack 101, but is not shown in the figure. The front end face and the front end units 102 of the shell, as well as the rear end face and the rear end units 102 of the shell, are fastened with bolts.

[0027] The power generation unit 1 has a unified electrode assembly (hereinafter referred to as UEA) 2 and a pair of front and rear separators 3, 3. The unified electrode assembly 2 has a membrane electrode assembly including an electrolyte membrane and electrodes. The pair of front and rear separators 3, 3 are disposed on the front and rear layers of UEA2 and sandwich UEA2. UEA2 and separators 3 are alternately arranged in the front-rear direction. UEA2 is a membrane electrode structure and can also be referred to as a membrane electrode component. Figure 1 Point P is the center point of power generation unit 1 in both the vertical and horizontal directions. Below, the side to center point P is sometimes referred to as the inner side, and the outer edge of power generation unit 1 (the side opposite to center point P) is referred to as the outer side.

[0028] Figure 2 This is a cross-sectional view showing the schematic structure of the power generation region of the unit stack 101. Figure 1 (Section II-II). (See section II-II). Figure 2 As shown, the partition 3 comprises a pair of thin metal plates, namely a front plate 3F and a rear plate 3R, with a corrugated cross-section. The front plate 3F is a generally rectangular plate component extending in both the vertical and horizontal directions, having a front surface 3Fa and a rear surface 3Fb. The rear plate 3R is a generally rectangular plate component extending in both the vertical and horizontal directions, having a front surface 3Ra and a rear surface 3Rb. The outer periphery of the rear surface 3Fb of the front plate 3F and the outer periphery of the front surface 3Ra of the rear plate 3R are joined together by welding or the like, thus forming an integral unit of the front plate 3F and the rear plate 3R. The partition 3 is made of a conductive material with excellent corrosion resistance, such as stainless steel, titanium, or titanium alloys.

[0029] Inside the partition 3 surrounded by the front plate 3F and the rear plate 3R, specifically between the rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R, a cooling flow path PAw for the flow of cooling medium is formed. The flow of the cooling medium cools the power generation surface of the power generation unit 1. The surfaces of the partition 3 opposite to the UEA2 (front surface 3Fa and rear surface 3Rb) are formed into an uneven shape through pressure molding or the like, to form a gas flow path between them and the UEA2. More specifically, the front plate 3F and the rear plate 3R have protrusions 31 protruding forward and backward toward the UEA2, respectively, and concave portions 32 connected to the protrusions 31 and formed into a concave shape.

[0030] The rear end face (abutment surface) 310a of the rear protrusion 31 abuts against the front surface 2a of UEA2. The front end face (abutment surface) 310c of the front protrusion 31 abuts against the rear surface 2b of UEA2. During the assembly of the fuel cell stack 100, a compressive load F is applied to the unit stack 101 in the front-rear direction, and in this state, the shell around the unit stack 101 and the front and rear end units 102 are fastened. Therefore, after the fuel cell stack 100 is assembled, the compressive load F on the unit stack 101 is maintained, and a specified surface pressure is applied to UEA2 in the front-rear direction via the protrusion 31.

[0031] Between the front surface 2a of UEA2 and the rear plate 3R of the partition 3, an anode flow path PAa for fuel gas flow is formed through a recess 32. The anode flow path PAa has a generally trapezoidal cross-section, having a bottom surface 320a of the recess 32 and a pair of inclined surfaces 320b extending obliquely upward and downward from the upper and lower ends of the bottom surface 320a toward the abutment surface 310a. The width of the anode flow path PAa (the vertical length of the recess 32) gradually increases from the bottom surface 320a toward the abutment surface 310a. The rear plate 3R is sometimes referred to as the anode partition.

[0032] Between the rear surface 2b of UEA2 and the front plate 3F of the partition 3, a cathode flow path PAc for the flow of oxidant gas is formed through a recess 32. The cathode flow path PAc has a generally trapezoidal cross-section, having a bottom surface 320c of the recess 32 and a pair of inclined surfaces 320d extending obliquely upwards and downwards from the upper and lower ends of the bottom surface 320c toward the contact surface 310c. The width of the cathode flow path PAc (the vertical length of the recess 32) gradually increases from the bottom surface 320c toward the contact surface 310c. Sometimes the front plate 3F is referred to as the cathode partition. Sometimes, fuel gas and oxidant gas are collectively referred to as reactant gases without distinction. Figure 2 In the diagram, the vertical positions and widths of the anolyte flow path PAa and the cathode flow path PAc are set to be equal, but in reality they are different (see reference). Figure 4 ).

[0033] Figure 3 This is a three-dimensional diagram representing the approximate structure of UEA2. For example... Figure 3 As shown, UEA2 has a generally rectangular membrane electrode assembly (MEA) 20 and a frame 21 supporting the MEA 20. Figure 2 In the middle, as a cross-sectional view of UEA2, a cross-sectional view of MEA20 is included. For example... Figure 2 As shown in the detailed diagram of part A, MEA20 has an electrolyte membrane 23, an anode electrode 24 disposed on the front surface 23f of the electrolyte membrane 23, and a cathode electrode 25 disposed on the rear surface 23r of the electrolyte membrane 23.

[0034] Electrolyte membrane 23 is, for example, a solid polymer electrolyte membrane, and can be a film of a perfluorosulfonic acid polymer containing water. It is not limited to fluorine-based electrolyte membranes, and hydrocarbon-based electrolyte membranes can also be used.

[0035] The anode electrode 24 has: an electrode catalyst layer 241 formed on the front surface 23f of the electrolyte membrane 23, serving as the reaction field for the electrode reaction; and a gas diffusion layer 242 disposed on the front surface of the electrode catalyst layer 241 for diffusing and supplying fuel gas. The cathode electrode 25 has: an electrode catalyst layer 251 formed on the rear surface 23r of the electrolyte membrane 23, serving as the reaction field for the electrode reaction; and a gas diffusion layer 252 disposed on the rear surface of the electrode catalyst layer 251 for diffusing and supplying oxidant gas. An intermediate layer (base layer) may also be disposed between the electrode catalyst layers 241, 251 and the gas diffusion layers 242, 252.

[0036] The electrode catalyst layers 241 and 251 contain a catalyst metal that promotes the electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidant gas, an electrolyte (ionomer, etc.) with proton conductivity, and carbon particles with electronic conductivity. The gas diffusion layers 242 and 252 are composed of conductive components with gas permeability, such as porous carbon materials.

[0037] At the anode electrode 24, the fuel gas (hydrogen) supplied via the anode flow path PAa is ionized under the action of a catalyst and moves towards the cathode electrode side through the electrolyte membrane 23. The electrons generated at this time are extracted as electrical energy through an external circuit. At the cathode electrode 25, the oxidant gas (oxygen) supplied via the cathode flow path PAc reacts with the hydrogen ions exported from the anode electrode 24 and the electrons moving from the anode electrode 24 to produce water. The generated water (called generated water) imparts appropriate humidity to the electrolyte membrane 23, and excess water is discharged to the outside of UEA2 along the gas flow. The generated water on the cathode side also flows towards the anode side through back diffusion via the electrolyte membrane 23. Therefore, both the fuel gas and the oxidant gas contain generated water. The fuel gas and the oxidant gas also contain condensate.

[0038] like Figure 3 As shown, the frame 21 is a generally rectangular thin plate made of resin, rubber, or other materials that are insulating and gas-impermeable. For example, PEN (polyethylene naphthalate) or PPS (polyphenylene sulfide) can be used as the constituent material. A generally rectangular opening 21a is formed in the center of the frame 21, and the MEA 20 is provided to cover the entire opening 21a. The frame 21 has a generally rectangular outer edge 221 and an inner edge 222. The outer edge 221 refers to the outer edge and periphery of the frame 21, and the inner edge 222 refers to the inner edge (the edge of the opening 21a) and periphery of the frame 21.

[0039] On the left side of the opening 21a of the frame 21, three through holes 201 to 203 are arranged vertically and penetrate the frame 21 in the front-to-back direction. On the right side of the opening 21a, three through holes 204 to 206 are arranged vertically and penetrate the frame 21 in the front-to-back direction. For ease of explanation, the through holes 201 to 206 are all represented as approximately rectangular, but the shape and position of the through holes 201 to 206 are not limited to this.

[0040] like Figure 1 As shown, on the partition plates 3 before and after UEA2, through holes 301 to 306 are respectively provided at positions corresponding to the through holes 201 to 206 of the frame 21, penetrating the partition plates 3 in the front-back direction. Through holes 301 to 306 communicate with the through holes 201 to 206 of the frame 21. Through these interconnected through holes 201 to 206 and 301 to 306, flow paths PA1 to PA6 (indicated by arrows for clarity) are formed, penetrating the unit stack 101 and extending in the front-back direction. Flow paths PA1 to PA6 are sometimes also called manifolds. Flow paths PA1 to PA6 are connected to external manifolds of the fuel cell stack 100.

[0041] The end units 102 at the front and rear of the unit stack 101 each have a plurality of plates arranged overlapping in the front-rear direction, but these are not shown in the figure. Specifically, the end unit 102 has a terminal plate arranged adjacent to the unit stack 101, an insulating plate arranged on the front-rear outer side of the terminal plate, and an end plate arranged on the front-rear outer side of the insulating plate.

[0042] The rear end unit 102 is a wet-side end unit through which reactant gases and cooling media pass, while the front end unit 102 is a dry-side end unit through which neither reactant gases nor cooling media pass. On the rear end unit 102, at positions corresponding to the through holes 201-206, 301-306 of the unit stack 101, a plurality of through holes 102a-102f penetrating the end unit 102 in the front-rear direction are provided. For ease of explanation, the through holes 102a-102f are all depicted as approximately rectangular, but the shape of the through holes 102a-102f is not limited to this.

[0043] Flow paths PA1 and PA6 (solid arrows) are for supplying and discharging fuel gases, respectively. Flow paths PA1 and PA6 are opposite to the anode flow path PAa (which is positioned opposite the front surface of the MEA20). Figure 2 As shown by the solid arrow, fuel gas flows to the right through flow paths PA1 and PA6 in the anode flow path PAa. The connection between the anode flow path PAa and other flow paths PA2 to PA5 is blocked by a seal (not shown).

[0044] Flow paths PA4 and PA3 (dashed arrows) are used for supplying and discharging oxidant gases, respectively. Flow paths PA4 and PA3 are positioned opposite the cathode flow path PAc on the rear surface of MEA20. Figure 2 As shown by the dashed arrow, the oxidant gas flows to the left through flow paths PA4 and PA3 in the cathode flow path PAc. The connection between the cathode flow path PAc and other flow paths PA1, PA2, PA5, and PA6 is blocked by a seal (not shown).

[0045] Flow paths PA5 and PA2 (single-dot dashed arrows) are for supplying and discharging the cooling medium, respectively. Flow paths PA5 and PA2 are connected to the cooling flow path PAw located inside the partition 3. Figure 2 The cooling medium flows through flow paths PA5 and PA2 into cooling flow path PAw. The connection between cooling flow path PAw and other flow paths PA1, PA3, PA4, and PA6 is blocked by a seal (not shown).

[0046] The power generation unit 1 of this embodiment is characterized by the structure of the partition 3. The structure of the partition 3 will be described in more detail below. Figure 4 This is a front view (viewed from the front) showing the general structure of the partition 3. More specifically, it is a front surface 3Fa of the partition 3 (front plate 3F) opposite the cathode electrode 25 on the rear surface 2b of UEA2. Figure 3 The diagram shows that region AR1, which is the area in MEA20 of UEA2 opposite to partition 3, generates electricity and is called the active region (power generation region). Region AR2, which is outside the active region AR1 (outside in the left-right and up-down directions), is the inactive region (non-power generation region).

[0047] like Figure 4 As shown, in the active area AR1 of the front plate 3F of the partition 3, multiple protrusions 31 are provided at equal intervals in the vertical direction over approximately its entire area. Figure 2 (The illustration is omitted.) Multiple protrusions 31 extend in the left-right direction, and recesses 32 are provided between adjacent protrusions 31 in the up-down direction. Figure 2 ). In multiple recesses 32 and the rear surface 2b of MEA20 ( Figure 2 Between them, a cathode flow path PAc is formed. In the active region AR1 of the rear plate 3R of the partition 3, multiple protrusions 31 are also provided at equal intervals in the vertical direction. Figure 2 (The diagram is omitted.) Furthermore, a recess 32 is provided between adjacent protrusions 31, 31 in the vertical direction. Figure 2 ), in multiple recesses 32 and the front surface 2a of MEA20 ( Figure 2 Between them, an anodic flow path PAa is formed.

[0048] Figure 4 Part B is a detailed diagram showing the structure of each gas flow path PAc and PAa. In this detailed diagram, the bottom surface 320c of the cathode flow path PAc is represented by a solid line. Figure 2 The boundary line intersecting the inclined surface 320d is represented by a dashed line, indicating the bottom surface 320a of the anode flow path PAa on the back side of the cathode flow path PAc. Figure 2 The boundary line where it intersects with inclined plane 320b. For example... Figure 4 As shown in the detailed diagram of Part B, the cathode flow path PAc (solid line) bends vertically like a snake, while extending horizontally in a wavy pattern. The anode flow path PAa (dashed line) also bends vertically like a snake, while extending horizontally in a wavy pattern. That is, the gas flow paths PAc and PAa are formed by alternating horizontal connections of upwardly convex bends (mountain-side bends) PAc1 and PAa1 and downwardly convex bends (valley-side bends) PAc2 and PAa2.

[0049] The mountain-side bend PAc1 of the cathode flow path PAc and the valley-side bend PAa2 of the anode flow path PAa, as well as the valley-side bend PAc2 of the cathode flow path PAc and the mountain-side bend PAa1 of the anode flow path PAa, are located at the same position in the left-right direction. Therefore, the spacing of the cathode flow path PAc in the length direction (the length from the adjacent bend PAc1 in the left-right direction to the bend PAc1) and the spacing of the anode flow path PAa in the length direction (the length from the adjacent bend PAa1 in the left-right direction to the bend PAa1) are equal to each other, and the gas flow paths PAc and PAa are staggered by half a spacing in the left-right direction. In other words, the phase difference between the gas flow paths PAa and PAc is π, and the gas flow paths PAa and PAc are formed in a form that is out of phase with each other.

[0050] On the other hand, the spacing Pc between the cathode flow paths PAc and PAc arranged vertically is shorter than the width spacing Pa between the anode flow paths PAa and PAa arranged vertically. Therefore, the overall area of ​​the cathode flow path PAc is larger than the overall area of ​​the anode flow path PAa. This is because the oxidant gas has a large pressure loss and is not easy to flow.

[0051] In the inactive region AR2 of the front surface 3Fa of the front plate 3F of the partition 3, multiple convex ridges, i.e., metal convex ridge sealing portions, are formed by pressure molding and protrude forward toward the frame 21. The multiple convex ridges have multiple end convex ridges 331 that surround the through holes 301, 302, 305, and 306 respectively, and outer convex ridges 332 that surround the active region AR1, the inactive region AR2 above and below it, and the through holes 303 and 304 for the passage of oxidant gas.

[0052] For example, a resin seal is fixed to the top of the protruding ridges 331 and 332. Figure 6 The protruding ridges 331 and 332 are tightly abutted against the rear surface 2b of the UEA2 (frame 21) by a seal, thereby forming a flow space that is sealed from the outside and allows oxidant gas to flow from the through hole 304 to the cathode flow path PAc and the through hole 303. Alternatively, the seal can be omitted, allowing the tops of the protruding ridges 331 and 332 to directly abut against the rear surface of the frame 21. An end protruding ridge 331 may also be provided inside the outer protruding ridge 332 and around the through holes 303 and 304. In this case, a channel portion may be provided that intersects the end protruding ridge 331 and protrudes rearward from the front surface 3Fa of the front plate 3F, with the inner and outer sides of the end protruding ridge 331 communicating through the channel portion.

[0053] Similarly, in the inactive region AR2 of the rear surface 3Rb of the rear plate 3R of the partition 3, multiple convex ridges, i.e., metal convex ridge seals, protruding rearward toward the frame 21 are provided by pressure molding, but are not shown in the figure. The multiple convex ridges have multiple end convex ridges that surround the through holes 302 to 305, and outer convex ridges that surround the active region AR1, the inactive region AR2 above and below it, and the through holes 301 and 306 for fuel gas flow. The end convex ridges may also be provided together with the channel portion around the through holes 301 and 306. These convex ridges are in close contact with the front surface 2a of the UEA2 (frame 21) with or without a seal, thereby forming a flow space that is sealed from the outside and allows fuel gas to flow from the through hole 301 to the anode flow path PAa and the through hole 306.

[0054] The front plate 3F and the rear plate 3R of the partition 3 are welded together at the welding section 333 to form a single unit. For example... Figure 4 As shown by the dashed line, the welding portion 333 extends along the outer edge of plates 3F and 3R, outside the outer protrusion 332 and the end protrusion 331. Welding portions for the front plate 3F and rear plate 3R are also provided outside the through holes 301, 303, 304, and 306 (outside the end protrusion 331), respectively, surrounding the through holes 301, 303, 304, and 306, but these are not shown in the figure.

[0055] On the left and right sides of the active region AR1 on the front surface 3Fa of the partition 3, a plurality of generally cylindrical protrusions 334 are provided on the inner side of the outer ridge 332, facing forward, towards the UEA2. Similarly, on the left and right sides of the active region AR1 on the rear surface 3Rb of the partition 3, a plurality of generally cylindrical protrusions are provided on the inner side of the outer ridge 332, facing backward, towards the UEA2, but these are not shown in the figure. These protrusions 334 constitute buffer sections for homogenizing the flow of oxidant gas between the through holes 303, 304 and the cathode flow path PAc, and the flow of fuel gas between the through holes 301, 306 and the anode flow path PAa.

[0056] Alternatively, a guide portion can be provided instead of the protrusion 334, which is provided in such a way that it forms a flow path from the through hole 304 to the entire cathode flow path inlet and from the entire cathode flow path outlet to the through hole 303. Alternatively, the guide portion can be provided in such a way that it forms a flow path from the through hole 301 to the entire anode flow path inlet and from the entire anode flow path outlet to the through hole 306.

[0057] On the front surface 3Fa of the partition 3, between the active region AR1 and the outer protrusions 332 above and below it, bypass suppression sections 350 are respectively provided in the left-right direction. Similarly, on the rear surface 3Rb of the partition 3, between the active region AR1 and the outer protrusions 332 above and below it, bypass suppression sections 360 are respectively provided in the left-right direction. The bypass suppression section 350 has the function of preventing oxidant gas from flowing through the cathode flow path PAc and bypassing it. The bypass suppression section 360 has the function of preventing fuel gas from flowing through the anode flow path PAa and bypassing it.

[0058] The structures of the bypass suppression sections 350 and 360 are described in detail. Figure 5A This refers to the structure of the bypass suppression section 350 on the front surface 3Fa of the partition 3. Figure 4 Enlarged view of the V-section, Figure 5B This refers to the structure of the bypass suppression section 360 on the rear surface 3Rb of the partition 3. Figure 4 An enlarged view of the opposite side of the V section (rear surface 3Rb). Hereinafter, the side facing the rear of the front plate 3F and the side facing the front of the rear plate 3R, i.e., the side facing the cooling medium (opposite side of UEA2), are sometimes referred to as the cooling medium side. Additionally, the side facing the front of the front plate 3F and the side facing the rear of the rear plate 3R, i.e., the gas flow path PAa and PAc sides (UEA2 side), are sometimes referred to as the gas side.

[0059] In the following explanation, the gas side is used as the reference. When viewed from the gas side, the part protruding towards the gas side is called a convex part, and the part protruding towards the cooling medium side is called a concave part. When the cooling medium side is used as the reference, the relationship between the concave and convex parts is reversed.

[0060] like Figure 5A , Figure 5B As shown, the outer convex portion 332 below (outer side) of the bypass suppression portions 350 and 360 has a predetermined width W in the vertical direction, and extends in the left and right directions while bending in the vertical direction like a snake. That is, the outer convex portion 332 is formed into a wave shape by alternating connection of an upwardly convex curved portion (mountain side curved portion) 332a and a downwardly convex curved portion (valley side curved portion) 332b in the left and right directions.

[0061] The spacing of the outer convex ridges 332, which correspond to the wavelength of the waveform, in the longitudinal direction (left-right direction) is half the spacing of the gas flow paths PAa and PAc in the longitudinal direction. Therefore, the valley-side bend 332b is located at the same position in the left-right direction as the mountain-side bends PAc1 and PAa1 and the valley-side bends PAc2 and PAa2 of the gas flow paths PAc and PAa. The mountain-side bend 332a is located in the middle of the left-right direction between the mountain-side bends PAc1 and PAa1 and the valley-side bends PAc2 and PAa2 of the gas flow paths PAc and PAa.

[0062] The welded portion 333 bends vertically in a serpentine manner, approximately parallel to the outer protruding ridge 332, while extending horizontally. Because the width (vertical length) of the welded portion 333 is small, therefore, in Figure 5A The welded portion 333 is indicated by a solid line. On the outer side of the welded portion 333 ( Figure 5A On the lower middle side, a flange 335 is provided, which curves vertically like a snake and extends horizontally, approximately parallel to the outer ridge 332. The outer ridge 332 protrudes towards the gas side, the welded portion 333 protrudes towards the cooling medium side, and the flange 335 protrudes towards the gas side (see reference). Figure 6 ).

[0063] like Figure 5A As shown, the bypass suppression section 350 has a flat section 351 that is generally flat in the vertical and horizontal directions, and a plurality of longitudinally elongated recesses 352 and a plurality of transversely elongated recesses 353 that are recessed into the cooling medium side from the flat section 351, or in other words, protruding into the cooling medium side. The plurality of longitudinally elongated recesses 352 are each elongated in the vertical direction and are arranged side by side at equal intervals in the horizontal direction. Specifically, a predetermined number (6 in the figure) of longitudinally elongated recesses 352 are arranged at equal intervals between adjacent mountain-side bends PAc1 and PAc1 in the horizontal direction of the cathode flow path PAc.

[0064] The longitudinally elongated recess 352 has a bottom surface 352a and an inclined surface 352b that slopes upwards from the bottom surface 352a toward the gas side. From the bottom surface 352a to the flat portion 351, its width (length in the left-right direction) and length (length in the up-down direction) gradually increase. The upper and lower ends of the longitudinally elongated recess 352 are formed into approximately arc shapes. The width of the longitudinally elongated recess 352 is approximately constant along its entire length in the up-down direction. The widths of the plurality of longitudinally elongated recesses 352 are the same.

[0065] On the other hand, the lengths of the multiple longitudinally elongated recesses 352 are not the same. Specifically, among the longitudinally elongated recesses 3521 opposite to the mountain-side bend PAc1, the longitudinally elongated recesses 3522 opposite to the valley-side bend PAc2, the longitudinally elongated recesses 3523 to the left and right of the longitudinally elongated recesses 3521, and the longitudinally elongated recesses 3524 to the left and right of the longitudinally elongated recesses 3522, the longitudinally elongated recess 3521 is the longest, and the longitudinally elongated recess 3524 is the shortest. The multiple longitudinally elongated recesses 352 are arranged symmetrically to the left and right with respect to the longitudinally elongated recess 3521.

[0066] The upper ends of the longitudinally elongated recesses 3521 and 3523 are equidistant in the vertical direction. The upper end of the longitudinally elongated recess 3524 is located below (outer side) of the upper ends of the longitudinally elongated recesses 3521 and 3523, and the upper end of the longitudinally elongated recess 3522 is located below (outer side) of the upper end of the longitudinally elongated recess 3524. That is, from the mountain-side bend PAc1 to the valley-side bend PAc2 of the cathode flow path PAc, the position of the upper end of the longitudinally elongated recess 352 gradually shifts downward. Accordingly, between the plurality of longitudinally elongated recesses 352 and the recess 320 constituting the lowermost cathode flow path PAc, a flat portion 351 that is continuous and uninterrupted in the left-right direction and has a vertical length of more than a predetermined length can be formed.

[0067] The lower ends of the longitudinal long recesses 3521 and 3522 are equidistant in the vertical direction, as are the lower ends of the longitudinal long recesses 3523 and 3524. The lower ends of the longitudinal long recesses 3521 and 3522 are located further down (outer) than the lower ends of the longitudinal long recesses 3523 and 3524. The left-right positions of the longitudinal long recesses 3521 and 3522 are the same as the left-right positions of the valley-side curved portion 332b of the outer convex ridge 332.

[0068] Multiple transversely elongated recesses 353 are disposed between multiple longitudinally elongated recesses 352 and the outer convex ridge 332. More specifically, the transversely elongated recesses 353 are connected to the mountain-side curved portion 332a of the outer convex ridge 332, and extend in a generally arc shape in the left-right direction with the mountain-side curved portion 332a as the center. The transversely elongated recesses 353 have a bottom surface 353a and an inclined surface 353b that rises from the bottom surface 353a towards the gas side. From the bottom surface 353a to the flat portion 351, its width (vertical length) and length (left-right length) gradually increase.

[0069] The width of the transverse long recess 353 is approximately constant along its entire length in the left-right direction. Multiple transverse long recesses 353 are arranged symmetrically left and right with reference to the position of the mountain-side bend PAc1. For example, on the right side of the mountain-side bend PAc1, the left end of the transverse long recess 353 is located between and near the longitudinal long recess 3521 and the longitudinal long recess 3523. The right end of the transverse long recess 353 is located between and near the longitudinal long recess 3522 and the longitudinal long recess 3524.

[0070] The lower (outer) edge of the flat portion 351 has an arcuate portion 351a extending in a generally arcuate shape along the transverse long recess 353, and a protrusion 351b protruding towards the valley side curving portion 332b between adjacent transverse long recesses 353, 353 in the left-right direction. The front surface 3Fa of the partition 3 extends downward (outer) towards the gas side in the region AR10 between the protrusion 351b and the valley side curving portion 332b of the lower outer convex ridge 332, and then extends downward approximately parallel to the rear surface 2b of the UEA2.

[0071] Furthermore, the front surface 3Fa of the partition 3 extends obliquely toward the gas side from the left end of the transversely elongated recess 353 on the right side of the protrusion 351b and the right end of the transversely elongated recess 353 on the left side of the protrusion 351b, and then extends approximately parallel to the rear surface 2b of the UEA2 in the left-right direction at the middle portion of the region AR10. Therefore, in the region AR10, the front surface 3Fa of the partition 3 protrudes toward the gas side more than the flat portion 351.

[0072] like Figure 5BAs shown, the bypass suppression section 360 has a flat section 361 that is substantially flat in the vertical and horizontal directions, and a plurality of longitudinally elongated recesses 362 and a plurality of transversely elongated recesses 363 that are recessed into the cooling medium side from the flat section 361, or in other words, protruding into the cooling medium side. The plurality of longitudinally elongated recesses 362 are each elongated in the vertical direction and are arranged side by side at equal intervals in the horizontal direction. Specifically, a predetermined number (6 in the figure) of longitudinally elongated recesses 362 are arranged at equal intervals between adjacent bends PAa1 and PAa1 in the horizontal direction of the anode flow path PAa.

[0073] The longitudinally elongated recess 362 has a bottom surface 362a and an inclined surface 362b that slopes upwards from the bottom surface 362a toward the gas side. From the bottom surface 362a to the flat portion 361, its width (length in the left-right direction) and length (length in the up-down direction) gradually increase. The upper and lower ends of the longitudinally elongated recess 362 are formed into approximately arc shapes. The width of the longitudinally elongated recess 362 is approximately constant along its entire length in the up-down direction. The widths of the plurality of longitudinally elongated recesses 362 are the same.

[0074] On the other hand, the lengths of the multiple longitudinally elongated recesses 362 are not the same. Specifically, among the longitudinally elongated recesses 3621 opposite to the mountain-side bend PAa1, the longitudinally elongated recesses 3622 opposite to the valley-side bend PAa2, the longitudinally elongated recesses 3623 to the left and right sides of the longitudinally elongated recesses 3621, and the longitudinally elongated recesses 3624 to the left and right sides of the longitudinally elongated recesses 3622, the longitudinally elongated recess 3621 is the longest, and the longitudinally elongated recess 3622 is the shortest. The multiple longitudinally elongated recesses 362 are arranged symmetrically about the longitudinally elongated recess 3621.

[0075] The upper end of the longitudinally elongated recess 3621 is located at the top (inner side), the upper end of the longitudinally elongated recess 3623 is located below (outer side) the upper end of the longitudinally elongated recess 3621, and the upper end of the longitudinally elongated recess 3624 is located below (outer side) the upper end of the longitudinally elongated recess 3623, and the upper end of the longitudinally elongated recess 3622 is located below (outer side) the upper end of the longitudinally elongated recess 3624. That is, from the mountain-side bend PAa1 of the anode flow path PAa to the valley-side bend PAa2, the position of the upper end of the longitudinally elongated recess 362 gradually shifts downward. Accordingly, between the plurality of longitudinally elongated recesses 362 and the recess 320 constituting the lowermost anode flow path PAa, a flat portion 361 that is continuous and uninterrupted in the left-right direction and has a length of more than a predetermined length in the vertical direction can be formed.

[0076] The lower ends of the longitudinal long recesses 3621 and 3622 are equidistant in the vertical direction, as are the lower ends of the longitudinal long recesses 3623 and 3624. The lower ends of the longitudinal long recesses 3621 and 3622 are located slightly lower (outer) than the lower ends of the longitudinal long recesses 3623 and 3624. The left-right positions of the longitudinal long recesses 3621 and 3622 are the same as the left-right positions of the valley-side curved portion 332b of the outer convex ridge 332.

[0077] Multiple transversely elongated recesses 363 are disposed between multiple longitudinally elongated recesses 362 and the outer convex ridge 332. More specifically, the transversely elongated recesses 363 are connected to the mountain-side curved portion 332a of the outer convex ridge 332, and extend in a generally arc shape in the left-right direction with the mountain-side curved portion 332a as the center. The transversely elongated recesses 363 have a bottom surface 363a and an inclined surface 363b that rises from the bottom surface 363a towards the gas side. From the bottom surface 363a to the flat portion 361, its width (vertical length) and length (left-right length) gradually increase.

[0078] The width of the transverse long recess 363 is approximately constant along its entire length in the left-right direction. Multiple transverse long recesses 363 are arranged symmetrically left and right with reference to the position of the mountain-side bend PAa1. For example, on the right side of the mountain-side bend PAa1, the left end of the transverse long recess 363 is located between and near the longitudinal long recess 3621 and longitudinal long recess 3623. The right end of the transverse long recess 363 is located between and near the longitudinal long recess 3622 and longitudinal long recess 3624.

[0079] The lower (outer) edge of the flat portion 361 has an arcuate portion 361a extending in a generally arcuate shape along the transverse long recess 363, and a protrusion 361b that slightly curves towards the valley side between adjacent transverse long recesses 363, 363 in the left-right direction. The rear surface 3Rb of the partition 3 extends downward (outer) towards the gas side in the region AR20 between the protrusion 361b and the valley side curve 332b of the lower outer convex ridge 332, and then extends downward approximately parallel to the front surface 2a of the UEA2.

[0080] Furthermore, the rear surface 3Rb of the partition 3 extends obliquely toward the gas side from the left end of the transversely elongated recess 363 on the right side of the protrusion 361b and the right end of the transversely elongated recess 363 on the left side of the protrusion 361b, and then extends approximately parallel to the front surface 2a of the UEA2 in the left-right direction at the middle portion of the region AR20. Therefore, in the region AR20, the rear surface 3Rb of the partition 3 protrudes toward the gas side more than the flat portion 351. The amount of protrusion of the protrusion 361b on the anode side is small, or the protrusion 361b may not be present.

[0081] The multiple longitudinally elongated recesses 352 (3521-3524) of the front panel 3F and the multiple longitudinally elongated recesses 362 (3621-3624) of the rear panel 3R are located at the same position in the left-right direction. Therefore, the rear end faces of the multiple longitudinally elongated recesses 352 and the front end faces of the multiple longitudinally elongated recesses 362 abut against each other. Specifically, longitudinally elongated recesses 3521 and 3622, longitudinally elongated recesses 3522 and 3621, longitudinally elongated recesses 3523 and 3624, and longitudinally elongated recesses 3524 and 3623 abut against each other respectively. At this time, the rear end face of the transversely elongated recess 353 and the front end face of the transversely elongated recess 363 also abut against each other.

[0082] The cross-sectional shape of power generation unit 1 is described. Figure 6 It is along Figure 5A , Figure 5B A cross-sectional view of power generation unit 1 cut along line VI-VI. Figure 7 It is along Figure 5A , Figure 5B A cross-sectional view of power generation unit 1 cut along line VII-VII. Figure 6 , Figure 7 This diagram schematically illustrates the structure of a single power generation unit 1, specifically, it schematically shows the structure from interface SF1 on the rear end face of the specified front plate 3F to interface SF2 on the front end face of the specified rear plate 3R. Interfaces SF1 and SF2 extend in the upward, downward, left, and right directions, and the interfaces SF1 and SF2 of adjacent power generation units 1 and 1 in the front-back direction are identical. Figure 6 , Figure 7 In this document, for ease of explanation, the scaling ratios of some structures (such as thickness) are appropriately altered relative to their actual dimensions.

[0083] like Figure 6 , Figure 7 As shown, the frame 21 of UEA2 is composed of a front frame 21F and a rear frame 21R. An adhesive (not shown) is applied between the rear surface 21Fb of the front frame 21F and the front surface 21Ra of the rear frame 21R, and the front frame 21F and rear frame 21R are integrally joined by the adhesive. The inner edge 222 of the front frame 21F ( Figure 3The inner edge of the front frame 21F extends upward (inward) from the inner edge 222 of the rear frame 21R. Therefore, the inner edge of the front frame 21F is located above the inner edge of the rear frame 21R.

[0084] An electrolyte membrane 23 and an anode-side electrode catalyst layer 241 are disposed on the inner side of the inner edge of the front frame 21F. The outer edges of the electrolyte membrane 23 and the outer edges of the electrode catalyst layer 241 are equidistant in the vertical direction, and the electrolyte membrane 23 and the electrode catalyst layer 241 are disposed at a predetermined gap from the inner edge of the front frame 21F. An anode-side electrode catalyst layer 251 is disposed on the inner side of the inner edge of the rear frame 21R. The electrode catalyst layer 251 extends downward (outward) beyond the inner edge of the front frame 21F, and the electrode catalyst layer 251 is disposed at a predetermined gap from the inner edge of the rear frame 21R.

[0085] The gas diffusion layer 242 on the anode side extends downward (outward) beyond the outer edge of the electrolyte membrane 23 and the electrode catalyst layer 241, as well as the inner edge of the front frame 21F. Furthermore, the lower end of the gas diffusion layer 242, i.e., the outer edge 242a, overlaps with the inner edge 222 of the front frame 21F and is in close contact with the front surface 21Fa of the front frame 21F. The gas diffusion layer 252 on the cathode side extends downward (outward) beyond the outer edge of the electrode catalyst layer 251 and the inner edge of the rear frame 21R. Furthermore, the lower end of the gas diffusion layer 252, i.e., the outer edge 252a, overlaps with the rear frame 21R and is in close contact with the rear surface 21Rb of the rear frame 21R. The vertical positions of the outer edges of the gas diffusion layers 242 and 252 are equal.

[0086] In this way, the gas flow paths PAa and PAc are sealed through the close contact between the gas diffusion layers 242 and 252 and the frames 21F and 21R. As a result, it is possible to prevent the reaction gas and generated water from leaking from the gas flow paths PAa and PAc into the space SP1 formed between the gas diffusion layers 242 and 252, the outer protrusion 332 and the partition 3 via the contact surface between UEA2 and the partition 3.

[0087] The rear end face 32r of the recess 32 forming the cathode flow path PAc, and the rear end face 352r of the longitudinally long recess 352 ( Figure 7 ), the rear end face 353r of the transverse long recess 353 ( Figure 6 The rear end face 333r of the rib 333a (the part where the weld portion 333 is provided) located below (outer side) of the outer protruding ridge 332 protrudes rearward by a predetermined length, and they are located on the interface SF1. The front end face 32f of the recess 32 forming the anode flow path PAa, the front end face 362f of the longitudinally long recess 362 ( Figure 7 ), the front end face 363f of the transverse long recess 363 ( Figure 6The front end face 333f of the rib 333b (the part where the welded part 333 is provided) located below (outer side) of the outer protruding rib 332 protrudes forward by a predetermined length, and they are located on the interface SF2.

[0088] The rear end face 32r of the recess 32 forming the cathode flow path PAc and the front end face 32f of the recess 32 forming the anode flow path PAa abut against each other (see reference). Figure 4 (Detailed view of part B). The rear end face 352r of the longitudinal long recess 352 and the front end face 362f of the longitudinal long recess 362 abut against each other. The rear end face 353r of the transverse long recess 353 and the front end face 363f of the transverse long recess 363 abut against each other. The rear end face 333r of the rib 333a and the front end face 333f of the rib 333b abut against each other. A welded part 333 is provided on the abutting surface of the ribs 333a and 333b.

[0089] The front end face (abutment face 310c) of the protrusion 31 protruding forward from the cathode flow path PAc and the surface (front end face) of the flat portion 351 of the bypass suppression portion 350 are located on the imaginary plane SF10, which extends approximately parallel to the interface SF1 at a position forward of the interface SF1. The surfaces of the abutment face 310c and the flat portion 351 are pressed against the rear end face of the gas diffusion layer 252, thereby sealing the cathode flow path PAc.

[0090] The front end faces of the outer ridge portion 332 and the flange portion 335 of the front panel 3F are located further forward than the imaginary plane SF10. A seal 336 is fixed to the front end face of the outer ridge portion 332, and the outer ridge portion 332 is pressed against the outer edge portion 221 (near the outer edge) of the rear frame 21R by the seal 336. The flange portion 335 abuts against the outer edge portion 221 of the rear frame 21R without the seal. Therefore, the front end face of the flange portion 335 is located further forward than the front end face of the outer ridge portion 332, and the difference in distance corresponds to the thickness of the seal 336.

[0091] The rear end face (abutment face 310a) of the protrusion 31 protruding rearward from the anodic flow path PAa and the surface (rear end face) of the flat portion 361 of the bypass suppression portion 360 are located on the imaginary plane SF20, which extends approximately parallel to the interface SF2 further rearward than the interface SF2. The surfaces of the abutment face 310a and the flat portion 361 are pressed against the front end face of the gas diffusion layer 242, thereby sealing the anodic flow path PAa.

[0092] The rear end face of the outer ridge 332 and the rear end face of the flange 335 of the rear plate 3R are located further rearward than the imaginary plane SF20. A seal 336 is fixed to the rear end face of the outer ridge 332, and the outer ridge 332 is pressed against the outer edge 221 (near the outer edge) of the front frame 21F by the seal 336. The flange 335 abuts against the front frame 21F without the seal. Therefore, the rear end face of the flange 335 is located further rearward than the rear end face of the outer ridge 332, and the difference in distance corresponds to the thickness of the seal 336.

[0093] like Figure 7 As shown, the front plate 3F is located between the flat portion 351 below the longitudinally elongated recess 352 and the outer convex portion 332. Figure 5A The region AR10 has a bulge 354 that bulges forward further than the flat portion 351. The gap between the bulge 354 and the rear frame 21R is smaller than the gap between the flat portion 351 and the rear frame 21R. The bulge 354 may be located on the same plane as the front end face of the outer convex portion 332, or it may be located rearward than the front end face of the outer convex portion 332.

[0094] Additionally, between the flat portion 361 below the longitudinally elongated recess 362 and the outer convex portion 332 of the rear plate 3R ( Figure 5B The region AR20 has a bulge 364 that bulges rearward from the flat portion 361. The gap between the bulge 364 and the front frame 21F is smaller than the gap between the flat portion 361 and the front frame 21F. The bulge 364 may be located on the same plane as the rear end face of the outer convex portion 332, or it may be located in front of the rear end face of the outer convex portion 332.

[0095] Figure 8 It is along Figure 5A A cross-sectional view of power generation unit 1 cut along line VIII-VIII. (See attached image.) Figure 8 As shown, the space between the multiple transversely elongated recesses 353 arranged side by side in the left-right direction and the rear frame 21R is connected via the gap between the bulge 354 and the rear frame 21R. Thus, a flow path bypassing the cathode path PAc is formed between the front plate 3F of the partition 3 and the rear frame 21R via the transversely elongated recesses 353 and the bulge 354. Figure 5A The bypass flow path PAb (cathode-side bypass flow path PAb1) is as follows. In the cathode-side bypass flow path PAb1, such as... Figure 8 As indicated by the arrow, the oxidant gas flows from right to left. However, the bypass flow path PAb1 is throttled at the bulge 354, thus inhibiting the flow of the oxidant gas.

[0096] Furthermore, the space between the multiple transversely elongated recesses 363 arranged side by side in the left-right direction and the front frame 21F is connected via the gap between the bulge 364 and the front frame 21F. Thus, a flow path PAa is formed between the rear plate 3R of the partition 3 and the front frame 21F, bypassing the anode flow path PAa via the transversely elongated recesses 363 and the bulge 364. Figure 5B The bypass flow path PAb (anode-side bypass flow path PAb2) is as follows. In the anode-side bypass flow path PAb2, such as... Figure 8 As indicated by the arrow, the fuel gas flows from left to right. However, the bypass flow path PAb2 is throttled at the bulge 364, thus inhibiting the flow of fuel gas.

[0097] like Figure 6 As shown, the outer protruding ridge 332 is positioned lower (outer) than the lower ends (outer edges) of the gas diffusion layers 242 and 252. The transversely elongated recesses 353 and 363 of the partition 3 are also positioned lower than the lower ends of the gas diffusion layers 242 and 252. Figure 7 As shown, the upper ends of the longitudinally elongated recesses 352 and 362 of the partition 3 are located above (inner) than the lower ends of the gas diffusion layers 242 and 252, while the lower ends of the longitudinally elongated recesses 352 and 362 are located below (outer) than the lower ends of the gas diffusion layers 242 and 252. In other words, the lower ends of the gas diffusion layers 242 and 252 are located in the middle of the longitudinally elongated recesses 352 and 362.

[0098] The feature of this embodiment is the positional relationship between the bypass suppression units 350, 360 and UEA2, especially the positional relationship in the vertical direction. Figure 9 This diagram shows the positional relationship between the bypass suppression section 350 of the front panel 3F and UEA2. The positional relationship between the bypass suppression section 360 of the rear panel 3R and UEA2 is also shown. Figure 9 Similarly, but the illustration is omitted.

[0099] like Figure 9 As shown, the outer edge (lower end face) SF11 of the electrolyte membrane 23 and the anode-side electrode catalyst layer 241 is located above (inner) the lower end of the cathode flow path PAc. The outer edge (lower end face) SF12 of the cathode-side electrode catalyst layer 251 is located near the upper end of the longitudinally elongated recess 352. The outer edge (lower end face) SF13 of the gas diffusion layers 242 and 252 is located near the lower end of the longitudinally elongated recess 352. The power generation unit 1 can generate electricity in the active region AR1 where the electrolyte membrane 23, anode electrode 24, and cathode electrode 25 overlap. In this embodiment, the active region AR1 does not overlap with any of the multiple longitudinally elongated recesses 352, but is located above (inner) the longitudinally elongated recesses 352.

[0100] The various parts of the power generation unit 1 will have dimensional and assembly errors. Therefore, the position of the lower end face SF11 of the electrolyte membrane 23 and the electrode catalyst layer 241 relative to the separator 3 may shift within a specified range ΔSF11. Additionally, the position of the lower end face SF12 of the electrode catalyst layer 251 relative to the separator 3 may shift within a specified range ΔSF12. Furthermore, the position of the lower end face SF13 of the gas diffusion layers 242 and 252 relative to the separator 3 may shift within a specified range ΔSF13.

[0101] Even when the lower end face SF11 of the electrolyte membrane 23 and the electrode catalyst layer 241 is offset downwards to the maximum extent, the lower end face SF11 and the longitudinal long recess 352 on the cathode side and the longitudinal long recess 362 on the anode side will not overlap. In other words, the connecting line LN1 obtained by sequentially connecting the upper ends of multiple longitudinal long recesses 352 and 362 in the left-right direction is located outside the active region AR1 defined by the lower end face SF11. Therefore, it is possible to prevent the generated water generated in the active region AR1 from being retained in the longitudinal long recesses 352 and 362.

[0102] Furthermore, even when the lower end face SF13 of the gas diffusion layers 242 and 252 is offset upwards to the maximum extent, the lower end face SF13 overlaps with the longitudinally elongated recess 352 on the cathode side and the longitudinally elongated recess 362 on the anode side. In other words, the connecting line LN1 is covered by the gas diffusion layers 242 and 252 along its entire length. Therefore, at least the region AR3 of the flat portions 351 and 361 between the longitudinally elongated recesses 352 and 362 and the gas flow paths PAc and PAa is covered. Figure 9 The shaded areas are completely covered by gas diffusion layers 252 and 242. Therefore, it is possible to prevent gas flow paths PAc and PAa and longitudinal long recesses 352 and 362 from communicating through the gap between UEA2 and the partition 3.

[0103] Furthermore, even when the lower end face SF13 of the gas diffusion layers 242 and 252 is offset downward to the maximum extent, the lower end face SF13 does not overlap with the transverse elongated recess 353 on the cathode side and the transverse elongated recess 363 on the anode side. Therefore, the bypass flow path PAb formed along the multiple transverse elongated recesses 353 and 363 can be prevented from being blocked by the gas diffusion layers 242 and 252.

[0104] The main operations of the power generation unit 1 according to this embodiment will be explained. When through Figure 1 The flow path PA1 and through-hole 301 supply fuel gas to the anode flow path PAa, and through Figure 1When oxidant gas is supplied to the cathode flow path PAc through the flow path PA4 and through-hole 304, power generation occurs in the active region AR1. At this time, generated water is produced in the active region AR1, but the longitudinal recesses 352 and 362 do not face the active region AR1. Therefore, the generated water is not guided to the longitudinal recesses 352 and 362, and its retention in these recesses is suppressed. Furthermore, the iron ions dissolved from the separator 3 are suppressed from reaching the electrolyte membrane 23, thereby suppressing the degradation of the electrolyte membrane 23.

[0105] A portion of the reactant gas supplied through the through-holes 301 and 304 flows around the gas flow paths PAa and PAc, but this bypass flow is suppressed by the bypass suppression sections 350 and 360. The bypass suppression sections 350 and 360 not only suppress the bypass flow but also function to abut the front plate 3F and rear plate 3R of the partition 3 to bear the compressive load. Particularly in this embodiment, the bypass suppression sections 350 and 360 are provided with multiple longitudinally elongated recesses 352 and 362 protruding towards the cooling medium side, so that the bypass suppression sections 350 and 360 (flat sections 351 and 361) and the gas diffusion layers 242 and 252 abut over a larger area. Accordingly, compared to the case where convex portions protruding towards the gas side are provided, the flow path area of ​​the bypass flow can be reduced, thereby effectively suppressing the bypass flow.

[0106] like Figure 8 , Figure 9 As shown, the reactant gas bypassing gas flow paths PAa and PAc flows in the left-right direction through the bypass flow path PAb. The bypass suppression sections 350 and 360 have protrusions 351b and 361b protruding into the bypass flow path PAb. Figure 5A , Figure 5B ) and the bulges 354 and 364 that bulge out into the bypass flow path PAb Figure 8 Therefore, the area of ​​the bypass flow path PAb decreases between the adjacent transverse long recesses 353 and 353 in the left-right direction, thereby suppressing the bypass flow.

[0107] When stagnant water exists in the region opposite to the bypass suppression sections 350 and 360, the stagnant water can be attracted by the bypass flow of the reactant gas flowing in the bypass flow path PAb. In particular, throttling sections are provided in the bypass flow path PAb by protrusions 351b and 361b and bulges 354 and 364. Therefore, a pressure difference can be generated between the bypass flow path PAb and the longitudinally elongated recesses 352 and 362, improving the attraction effect of stagnant water. In the space SP1 outside UEA2, in the space inside the bypass flow path PAb formed by the transversely elongated recesses 353 and 363 and the bulges 354 and 364 and outside the gas diffusion layers 242 and 252, the reactant gas may also bypass in the left and right directions. However, since the transversely elongated recesses 353 and 363 extending in the left and right directions are provided in the bypass flow path PAb, bypass flow is more likely to occur compared with other regions.

[0108] The reactant gases bypassing gas flow paths PAa and PAc contain moisture, such as generated water and condensate. This moisture-containing reactant gas may become trapped in the longitudinal recesses 352 and 362 and the transverse recesses 353 and 363, forming trapped water containing iron ions dissolved from the partition 3 towards the bypass suppression sections 350 and 360. When this trapped water reaches gas flow paths PAa and PAc, it can cause deterioration of the electrolyte membrane 23. Therefore, it is necessary to prevent the trapped water from flowing into gas flow paths PAa and PAc.

[0109] In this respect, in this embodiment, the region AR3 (between the gas flow paths PAa, PAc of the partition 3 and the longitudinal recesses 352, 362) Figure 9 The shaded areas (the regions shown in the image) are continuously provided with flat portions 351 and 361 in the left-right direction. Therefore, when the gas diffusion layers 242 and 252 and the flat portions 351 and 361 are pressed together, the gas flow paths PAa and PAc and the longitudinal long recesses 352 and 362 can be reliably separated. As a result, stagnant water can be prevented from flowing from the bypass suppression portions 350 and 360 into the gas flow paths PAa and PAc, thereby suppressing the deterioration of the electrolyte membrane 23.

[0110] According to this embodiment, the following effects can be achieved.

[0111] (1) The power generation unit 1 has a UEA2 and a pair of partitions 3, 3 (rear plate 3R, front plate 3F). The UEA2 is constructed by integrating the MEA20 and the frame 21. The MEA20 has an electrolyte membrane 23 and an anode electrode 24 and a cathode electrode 25 respectively disposed on the front surface 23f and the rear surface 23r of the electrolyte membrane 23. The frame 21 supports the outer edge of the MEA20. The pair of partitions 3, 3 are respectively disposed opposite to the front surface 2a and the rear surface 2b of the UEA2, forming gas flow paths PAa and PAc between the anode electrode 24 and the cathode electrode 25 for the flow of reaction gas. Figures 1-3 At the abutment portion where the outer edge 221 of the frame 21 abuts against a pair of partitions 3, 3, an outer protruding ridge 332 and a sealing element 336 are provided as a sealing portion to prevent leakage of reactive gases. Figure 5A , Figure 5B The baffle 3 is located between the gas flow paths PAa and PAc and the outer protruding portion 332, and on the outside of the active region AR1 (power generation region) where the anode electrode 24, electrolyte membrane 23, and cathode electrode 25 overlap, it has bypass suppression portions 350 and 360 formed in an uneven shape towards UEA2 to suppress the flow of reactive gas around the gas flow paths PAa and PAc. Figure 6 , Figure 7 , Figure 9 ).

[0112] By configuring concave and convex bypass inhibition portions 350 and 360 on the outer side of the active region AR1, the generated water produced in the active region AR1 can be prevented from remaining in the longitudinally elongated recesses 352 and 362 of the partition 3. Therefore, the amount of iron ions dissolved from the partition 3 into the generated water, i.e., water containing iron ions, is reduced, thereby preventing this water from seeping into the electrolyte membrane 23 and thus inhibiting the deterioration of the electrolyte membrane 23. On the outer side of the active region AR1 ( Figure 9 The lower side of the MEA20 is provided with an electrode catalyst layer 251 and gas diffusion layers 242 and 252 on the cathode side. That is, the lower end faces SF11, SF12, and SF13 are staggered in the vertical direction, so the thickness variation at the end of the MEA20 is small. By arranging longitudinally elongated recesses 352 and 362 in this region with small thickness variation, the flat portions 351 and 361 are in good and tight contact with the MEA20, thereby easily ensuring the sealing performance between the MEA2 and the partition 3.

[0113] (2) The bypass suppression portions 350 and 360 have multiple longitudinally elongated recesses 352 and 362 arranged along the outer edges 242a and 252a of MEA20 (gas diffusion layer). Figure 5A , Figure 5B , Figure 6 , Figure 7The connecting line LN1, obtained by sequentially connecting the ends of the active regions AR1 of multiple longitudinally long recesses 352 and 362, is located outside the active region AR1. Figure 9 Accordingly, the multiple longitudinal recesses 352 and 362 will not be connected to the active region AR1 in their entire lateral direction, which can effectively prevent water from flowing between the gas flow paths PAa and PAc and the longitudinal recesses 352 and 362.

[0114] (3) The bypass suppression portions 350 and 360 have flat portions 351 and 361 opposite to UEA2, and a plurality of longitudinally elongated recesses 352 and 362 recessed from the flat portions 351 and 361 toward the opposite side of UEA2. Figure 5A , Figure 5B , Figure 6 , Figure 7 Accordingly, the bypass suppression sections 350 and 360 come into contact with UEA2 (mainly gas diffusion layers 242 and 252) over a large area through the flat sections 351 and 361, thus effectively suppressing the bypass flow of the reactive gas.

[0115] (4) The partition 3 (bypass suppression parts 350, 360) between the outer convex part 332 and the multiple longitudinal long recesses 352, 362, also has transverse long recesses 353, 363 and bulges 354, 364, which form a bypass flow path PAb that allows the reactant gas to flow around the gas flow paths PAa, PAc. Figure 8 Accordingly, since a throttling section is provided in the bypass flow path PAb, the bypass flow of the reactant gas can be suppressed. In addition, by the flow of the reactant gas in the bypass flow path PAb, the stagnant water in the bypass suppression sections 350 and 360 can be attracted and discharged.

[0116] (5) The partition 3 has a recess 32, which forms gas flow paths PAa and PAc that bend in a serpentine manner in the vertical direction and extend in the horizontal direction. Figure 5A , Figure 5B Flat portions 351 and 361 are provided extending between multiple longitudinally elongated recesses 352 and 362 and recess 32 to block the communication between the multiple longitudinally elongated recesses 352 and 362 and the gas flow paths PAa and PAc. Figure 5A , Figure 5B Accordingly, the gap between UEA2 and the partition 3 can be well sealed by the flat portions 351 and 361. As a result, even when a serpentine gas flow path PAa and PAc that is close to the bypass suppression portions 350 and 360 is used, it is possible to reliably prevent the generated water in the active region AR1 from entering the longitudinally long recesses 352 and 362.

[0117] (6) In a different viewpoint from the above, in this embodiment, the partition 3 has flat portions 351 and 361 between the gas flow paths PAa and PAc and the outer protrusion 332, and on the outside of the active region AR1 (power generation region) where the anode electrode 24, electrolyte membrane 23 and cathode electrode 25 overlap. The flat portions 351 and 361 continuously abut against the front surface 2a and rear surface 2b of UEA2 from one end to the other end in the flow direction of the gas flow paths PAa and PAc. Figure 6 , Figure 7 , Figure 9 ).

[0118] According to this structure, when stagnant water containing iron ions dissolved from the separator 3 is generated in the bypass suppression sections 350 and 360 outside the active region AR1, it is possible to prevent the stagnant water from reaching the gas flow paths PAa and PAc. As a result, it is possible to prevent the stagnant water from entering the electrolyte membrane 23 through the gas flow paths PAa and PAc, thereby preventing the deterioration of the electrolyte membrane 23.

[0119] (7) The anode electrode 24 and the cathode electrode 25 respectively have gas diffusion layers 242 and 252 that are disposed opposite to a pair of partitions 3, 3 and have gas permeability. Figure 2 The flat portions 351 and 361 abut against the surfaces of the gas diffusion layers 242 and 252. Figure 6 , Figure 7 Accordingly, the contact surfaces between the flat portions 351 and 361 and the gas diffusion layers 242 and 252 can be sealed without gaps, thereby reliably preventing water from flowing from the gas flow paths PAa and PAc into the space SP1 outside UEA2. Figure 6 , 7 The flow of water and gas from space SP1 to gas flow paths PAa and PAc is also observed. Furthermore, since the gas diffusion layers 242 and 252 are compressed by the load F in the front-to-back direction, even if the thickness of each part is incorrect due to the stacking offset of the power generation unit 1 or manufacturing errors, sufficient sealing between the gas diffusion layers 242 and 252 and the flat parts 351 and 361 can be ensured.

[0120] (8) Between the flat portions 351, 361 and the outer convex portion 332, the partition 3 has a plurality of longitudinally elongated recesses 352, 362 arranged along the outer edge portions 242a, 252a of the MEA20 (gas diffusion layer) and recessed into the UEA2. Figure 5A , Figure 5B , Figure 6 , Figure 7 The connecting line LN1, obtained by sequentially connecting the ends of the active regions AR1 side of multiple longitudinally long recesses 352 and 362, is covered by gas diffusion layers 242 and 252 along its entire length. Figure 9By ensuring that the connecting line LN1 is covered by gas diffusion layers 242 and 252 along its entire length, the multiple longitudinal recesses 352 and 362 are not connected to the active region AR1 in their entire lateral direction, reliably preventing water from flowing between the gas flow paths PAa and PAc and the longitudinal recesses 352 and 362. That is, the space SP1 between the gas flow paths PAa and PAc and the bypass suppression sections 350 and 360 is reliably separated, preventing water from flowing between the gas flow paths PAa and PAc and the space SP1.

[0121] As described above, in this embodiment, the plurality of longitudinally elongated recesses 352, 362 of a pair of partitions 3 are related to each other, that is, the rear end face 352r of the plurality of longitudinally elongated recesses 352 of the front plate 3F. Figure 7 ) and the front end face 362f of the multiple longitudinally elongated recesses 362 of the rear plate 3R ( Figure 7 ) abut against each other. In addition, the multiple transverse elongated recesses 353, 363 abut against each other, that is, the rear end faces 353r of the multiple transverse elongated recesses 353 of the front plate 3F. Figure 6 ) and the front end face 363f of the multiple transverse long recesses 363 of the rear plate 3R ( Figure 6 They abut against each other. The longitudinally elongated recesses 352 and 362 and the transversely elongated recesses 353 and 363 protrude towards the cooling medium side. Therefore, when the cooling medium side is taken as a reference (viewed from the cooling medium side), as... Figure 6 , Figure 7 As shown, the longitudinal long recesses 352 and 362 constitute the longitudinal long protrusions 3520 and 3620, and the transverse long recesses 353 and 363 constitute the transverse long protrusions 3530 and 3630.

[0122] At the abutting surfaces (rear end face 352r, front end face 362f) of the longitudinally elongated protrusions 3520 and 3620 and the abutting surfaces (rear end face 353r, front end face 363f) of the transversely elongated protrusions 3530 and 3630, such as Figure 2 As shown, a front-to-back load F is applied during the assembly of the fuel cell stack 100. At this time, due to assembly errors of the power generation unit 1 and the fuel cell stack 100, dimensional errors of individual components, etc., the center positions of the longitudinal long protrusion 3520 and the longitudinal long protrusion 3620 in the left and right directions may be offset.

[0123] When the center positions of the longitudinal protrusions 3520 and 3620 are offset, there is a possibility that the rear end face 352r of the longitudinal protrusion 3520 and the front end face 362f of the longitudinal protrusion 3620 will not abut, causing one protrusion (e.g., the longitudinal protrusion 3520) to enter the space between the other protrusion (e.g., the space facing the flat portion 361) when the rear end face 352r and the front end face 362f abut, if the abutment area is insufficient, there is a possibility that the longitudinal protrusions 3520 and 3620 will deform, causing one longitudinal protrusion 3520 to enter the space between the other longitudinal protrusions 3620 and 3620.

[0124] As a result, when a compressive load F is applied in the front-to-back direction, the partition 3 may deform and break. Therefore, in order to prevent the partition 3 from breaking due to the offset of the center position of the longitudinal protrusions 3520 and 3620, in this embodiment, the partition 3 is further configured as follows.

[0125] Figure 10 yes Figure 5A The cross-sectional view of XX (including cross-sectional views of gas diffusion layers 242 and 252) is shown with multiple power generation units 1 overlapping in the front-to-back direction for ease of explanation. For example... Figure 5A , Figure 5B As shown, multiple longitudinally elongated protrusions 3520 (longitudinally elongated recesses 352) and multiple longitudinally elongated protrusions 3620 (longitudinally elongated recesses 362) all extend in the vertical direction. Therefore, the center line CLc passing through the center of the width direction (left-right direction) of each of the multiple longitudinally elongated protrusions 3520 and extending in the length direction, and the center line CLa passing through the center of the width direction of each of the multiple longitudinally elongated protrusions 3620 and extending in the length direction, are parallel to each other.

[0126] exist Figure 10 The diagram shows the alignment of the center line CLc of the longitudinal elongated protrusion 3520 and the center line CLA of the longitudinal elongated protrusion 3620. At this time, in the top view of the power generation unit 1 (… Figure 4 In this configuration, center lines CLc and CLa overlap. In this state, the entire rear end face 352r of the longitudinally elongated protrusion 3520 on the cathode side, which has a generally trapezoidal cross-section, abuts against the front end face 362f of the longitudinally elongated protrusion 3620, which has a generally trapezoidal cross-section.

[0127] During fuel cell power generation, the pressure of the oxidant gas consistently acts on the cathode flow path PAc. On the other hand, fuel gas is injected by an injector when power generation is required, thus the pressure of the fuel gas intermittently acts on the anode flow path PAa. Therefore, the pressure of the oxidant gas in the cathode flow path PAc is generally greater than the pressure of the fuel gas in the anode flow path PAa. In the bypass suppression sections 350 and 360, the pressure of the oxidant gas (Ca) acting on the longitudinal protrusion 3520 is also greater than the pressure of the fuel gas (An) acting on the longitudinal protrusion 3620. Figure 10 Wa indicates the cooling medium (water).

[0128] like Figure 10 As shown, the width Wc (length in the left-right direction) of the longitudinally elongated protrusion 3520 on the cathode side is smaller than the width Wa (length in the left-right direction) of the longitudinally elongated protrusion 3620 on the anode side. Therefore, even if the centerlines CLa and CLac of the longitudinally elongated protrusions 3520 and 3620 are relatively offset in the left-right direction, the entire surface of the rear end face 352r of the longitudinally elongated protrusion 3520 can abut against the front end face 362f of the longitudinally elongated protrusion 3620, thus preventing deformation and damage to the partition 3. The longitudinally elongated protrusions 3520 and 3620 are elongated shapes extending in the vertical direction. Figure 5A , Figure 5B Therefore, even if the positions of the longitudinal protrusions 3520 and 3620 are relatively offset in the vertical direction, the longitudinal protrusions 3520 and 3620 can maintain a sufficient contact state.

[0129] Furthermore, by making the width Wc of the longitudinal protrusion 3520 on the cathode side smaller than the width Wa of the longitudinal protrusion 3620 on the anode side, the area in the contact surface of the longitudinal protrusions 3520 and 3620 subjected to the pressure of the oxidant gas on the high-pressure side can be limited. Accordingly, the pressure of the oxidant gas acting on the longitudinal protrusion 3520 can be effectively absorbed by the opposing longitudinal protrusions 3620. Conversely, the width Wc of the longitudinal protrusion 3520 can also be made larger than the width Wa of the longitudinal protrusion 3620.

[0130] Figure 6The rear end face 353r of the transversely elongated protrusion 3530 on the cathode side abuts against the front end face 363f of the transversely elongated protrusion 3630 on the anode side of the adjacent power generation unit 1. Accordingly, even below (outer side) of the longitudinally elongated protrusions 3520, 3620, the protrusions of the pair of plates 3F, 3R abut against each other. Thus, through the mutual abutment of the longitudinally elongated protrusions 3520, 3620 and the transversely elongated protrusions 3530, 3630, the pair of plates 3F, 3R abut against each other over a wide area, thereby enabling the partition to effectively distribute the load in the front-to-back direction throughout the entire area. The transversely elongated protrusions 3530, 3630 (transversely elongated recesses 353, 363) extend in the left-right direction orthogonally to the longitudinally elongated protrusions 3520, 3620 (longitudinally elongated recesses 352, 362), thereby suppressing the elongation of the bypass suppression portions 350, 360 in the vertical direction.

[0131] In addition to the above, this embodiment can also achieve the following effects.

[0132] (1) The power generation unit 1 has a UEA2 and a pair of partitions 3, 3 (rear plate 3R, front plate 3F), wherein the UEA2 is constructed by integrating the MEA20 and the frame 21. The MEA20 has an electrolyte membrane 23 and an anode electrode 24 and a cathode electrode 25 respectively disposed on the two surfaces of the electrolyte membrane 23; the frame 21 supports the outer edge of the MEA20; the pair of partitions 3, 3 are respectively disposed opposite to the front surface 2a and the rear surface 2b of the UEA2, forming gas flow paths PAa and PAc between the anode electrode 24 and the cathode electrode 25 for the flow of reaction gas. Figures 1-3 The front panel 3F has a plurality of longitudinally elongated protrusions 3520 disposed along the outer edge 221 of the UEA2 (frame 21) and protruding toward the opposite side of the rear surface 2b of the UEA2. Figure 5A , Figure 7 , Figure 10 The rear plate 3R has a plurality of longitudinally elongated protrusions 3620 disposed along the outer edge 221 of the UEA2 and protruding to the opposite side of the front surface 2a of the UEA2. Figure 5B , Figure 7 , Figure 10 Multiple longitudinally elongated protrusions 3520 are arranged along multiple center lines CLc parallel to each other, and have elongated shapes extending with a predetermined width Wc orthogonal to the multiple center lines CLc respectively. Figure 5A , Figure 10 Multiple longitudinally elongated protrusions 3620 are elongated in shape, extending along multiple center lines CLa parallel to each other, and each having a predetermined width Wa extending orthogonally to the multiple center lines CLa. Figure 5B , Figure 10In a top view taken from a front-to-back direction perpendicular to the front surface 2a of UEA2, center lines CLc and CLa are approximately parallel to each other, and width Wc is narrower than width Wa. Figure 10 ).

[0133] According to this structure, even if the centerline CLc of the longitudinal protrusion 3520 of the front plate 3F does not overlap with the centerline CLa of the longitudinal protrusion 3620 of the rear plate 3R during the assembly of the fuel cell stack 100 due to assembly errors, dimensional errors, etc., and is offset in the left and right direction, the entire surface of the rear end face 352r of the longitudinal protrusion 3520 can still abut against the front end face 362f of the longitudinal protrusion 3620. This ensures sufficient contact area between the longitudinal protrusions 3520 and 3620 and suppresses deformation and damage to the separator 3.

[0134] (2) The front plate 3F is a cathode partition that forms a cathode flow path PAc for oxidant gas flow between itself and the cathode electrode 25, and the rear plate 3R is an anode partition that forms an anode flow path PAa for fuel gas flow between itself and the anode electrode 24. Figure 2 , Figure 10 The pressure of the oxidant gas in the cathode flow path PAc is greater than the pressure of the fuel gas in the anode flow path PAa. However, by making the width Wc of the longitudinal protrusion 3520 on the cathode side smaller than the width Wa of the longitudinal protrusion 3620 on the anode side, the area in the contact portion of plates 3F and 3R subjected to the pressure of the oxidant gas on the high-pressure side can be limited. Accordingly, the pressure of the oxidant gas can be effectively absorbed by the opposing longitudinal protrusions 3620.

[0135] (3) At the contact portion where the outer edge 221 of the frame 21 abuts against the front plate 3F and the rear plate 3R, an outer protruding ridge 332 and a sealing element 336 are provided as a sealing portion to prevent leakage of the reaction gas. Figure 6 , Figure 7 The front panel 3F, between the multiple longitudinal elongated protrusions 3520 and the outer convex ridge 332, also has multiple transverse elongated protrusions 3530 protruding to the opposite side of the rear surface 2b of the UEA2. Figure 5A , Figure 6 The rear plate 3R, between the multiple longitudinal elongated protrusions 3620 and the outer convex ridge 332, also has multiple transverse elongated protrusions 3630 protruding to the opposite side of the front surface 2a of the UEA2. Figure 5B , Figure 6 Each of the plurality of transverse elongated protrusions 3530 and each of the plurality of transverse elongated protrusions 3630 extends elongatedly in a direction generally orthogonal to the center line CLc and the center line CLa (left-right direction). Figure 5A , Figure 5BAccordingly, even on the outer sides of the longitudinally elongated protrusions 3520 and 3620, a pair of plates 3F and 3R abut against each other. Therefore, the pair of plates 3F and 3R abut against each other over a large area, thus enabling them to effectively bear loads in the front-to-back direction throughout the entire partition.

[0136] (4) The center lines CLc and CLa extend in a direction approximately orthogonal to the flow direction (left-right direction) of the reacting gas along the gas flow paths PAc and PAa (up-down direction). Figure 5A , Figure 5B In the bypass suppression sections 350 and 360, the oxidant gas and fuel gas flow in opposite directions to each other. Therefore, assuming that when the center lines CLc and CLa are tilted to the left and right, the tilt directions of the center lines CLc and CLa are opposite to each other, the longitudinal protrusions 3520 and 3620 intersect each other. In this respect, by setting them without tilting the center lines CLc and CLa, the longitudinal protrusions 3520 and 3620 will not intersect but will overlap each other in the vertical direction, thereby increasing the contact area of ​​the longitudinal protrusions 3520 and 3620.

[0137] (5) The gas flow path includes the cathode flow path PAc and the anode flow path PAa. Figure 2 The cathode flow path PAc and the anode flow path PAa appear wavy when viewed from above and are in opposite phase to each other. Figure 4 Accordingly, the rear end face 32r of the recess 32 of the front plate 3F constituting the cathode flow path PAc ( Figure 6 ) and the front end face 32f of the recess 32 of the rear plate 3R that constitutes the anode flow path PAa. Figure 6 They intersect each other and can be uniformly abutted across the entire active region AR1.

[0138] Furthermore, regarding the drainage of stagnant water retained in the bypass suppression sections 350 and 360, in this embodiment, drainage can be achieved by allowing the reactant gas to flow along the bypass flow path PAb, which bypasses the gas flow paths PAa and PAc, as described above. That is, the stagnant water in space SP1 is attracted by the bypass flow along the bypass flow path PAb, thereby allowing the stagnant water to be discharged. In this regard, to improve drainage performance, the bypass suppression sections 350 and 360 can be further configured as follows.

[0139] Figure 11 This is a front view showing an example of a bypass suppression section 350 configured to improve drainage; it is a view of the front panel 3F from the front. Figure 11 Equivalent to Figure 5A Variations. For example... Figure 11As shown, the centerline CLc of the longitudinally elongated recess 352 extends downwards and to the left at a predetermined angle. That is, it extends obliquely towards the flow direction of the reactant gas in the bypass flow path PAb. When the angle formed by the axis CL0 extending in the vertical direction and the centerline CLc is defined as θ, the angle θ is a value greater than 0° and less than 90°, for example, 45°. The angle θ can also be a value greater than 45° (for example, around 60°) or a value less than 45° (for example, around 30°).

[0140] The lower end of the longitudinally elongated recess 352 extends to intersect with the transversely elongated recess 353, and the longitudinally elongated recess 352 and the transversely elongated recess 353 are connected by a connecting portion 355. More specifically, as the connecting portion 355, a notch 355a with the same width as the longitudinally elongated recess 352 is provided on the inclined surface 353b of the transversely elongated recess 353, and the longitudinally elongated recess 352 and the transversely elongated recess 353 are connected by the notch 355a. The depth (length in the front-to-back direction) of the notch 355a is equal to the depth of the longitudinally elongated recess 352. The depth of the notch 355a may also be shallower than the depth of the longitudinally elongated recess 352.

[0141] The longitudinally elongated recess 362 of the rear panel 3R and the longitudinally elongated recess 352 of the front panel 3F are symmetrically formed. That is, as shown... Figure 11 The middle section is shown as a dashed line, with the longitudinally elongated recess 362 extending downwards and to the right at a predetermined angle θ. That is, it extends obliquely toward the flow direction of the reactant gas in the bypass flow path PAb. Furthermore, the longitudinally elongated recess 362 and the transversely elongated recess 363 are connected by a connecting portion 365, more specifically, by a notch 365a in the transversely elongated recess 363.

[0142] In this way, the longitudinal long recesses 352 and 362 and the transverse long recesses 353 and 363 are connected by connecting portions 355 and 365 (notches 355a and 365a), thereby allowing the stagnant water in the longitudinal long recesses 352 and 362 to be easily drawn in along the gas flow of the bypass flow path PAb. Therefore, even if stagnant water is generated in the longitudinal long recesses 352 and 362, the stagnant water will not remain for a long time and can be easily discharged.

[0143] Furthermore, the longitudinally elongated recesses 352 and 362 extend obliquely toward the flow direction of the bypass flow path PAb. Therefore, when bypass flow occurs in the bypass flow path PAb, the stagnant water in the longitudinally elongated recesses 352 and 362 easily flows into the bypass flow path PAb. This promotes the discharge of stagnant water from the longitudinally elongated recesses 352 and 362. In this case, since the longitudinally elongated recesses 352 and 362 are arranged intersectingly, even if the widths Wc and Wa of the longitudinally elongated recesses 352 and 362 are... Figure 10Even if the center line CLc is offset in the left and right directions relative to the center line CLa, it is still possible to maintain the sufficient contact between the longitudinal long recesses 352 and 362.

[0144] In summary, this embodiment can also achieve the following effects.

[0145] (1) The power generation unit 1 has a UEA2 and a pair of partitions 3, 3 (rear plate 3R, front plate 3F), wherein the UEA2 is formed by integrating the MEA20 and the frame 21. The MEA20 has an electrolyte membrane 23 and an anode electrode 24 and a cathode electrode 25 respectively disposed on the front surface 23f and the rear surface 23r of the electrolyte membrane 23; the frame 21 supports the outer edge of the MEA20; the pair of partitions 3, 3 are respectively disposed opposite to the front surface 2a and the rear surface 2b of the UEA2, forming gas flow paths PAa and PAc between the anode electrode 24 and the cathode electrode 25 for the flow of reaction gas. Figures 1-3 At the abutment portion where the outer edge 221 of the frame 21 abuts against a pair of partitions 3, 3, an outer protruding ridge 332 and a sealing element 336 are provided as a sealing portion to prevent leakage of reactive gases. Figure 5A , Figure 5B The partition 3 has: bypass suppression portions 350, 360 (especially longitudinally elongated recesses 352, 362), which are formed in a concave-convex shape towards UEA2 between the gas flow paths PAc, PAa and the outer convex ridge 332 to suppress the flow of reactant gas bypassing the gas flow paths PAc, PAa; and transversely elongated recesses 353, 363 and bulges 354, 364, which are provided between the longitudinally elongated recesses 352, 362 and the outer convex ridge 332 to form a bypass flow path PAb for the reactant gas to flow around the gas flow paths PAc, PAa. Figure 6 A, 6B).

[0146] By allowing the reactant gas to flow in the bypass flow path PAb outside the longitudinal recesses 352 and 362, the stagnant water retained in the longitudinal recesses 352 and 362 can be attracted and discharged. As a result, iron ions can be prevented from dissolving from the partition 3 into the stagnant water, i.e., water containing iron ions can be prevented from entering the electrolyte membrane 23, thereby inhibiting the deterioration of the electrolyte membrane 23.

[0147] (2) The bypass suppression portions 350 and 360 have a plurality of longitudinally elongated recesses 352 and 362 arranged along the outer edge of MEA20 and recessed toward the opposite side of UEA2. Figure 5A , Figure 5B The bypass flow path forming section has multiple transversely elongated recesses 353, 363 that are recessed toward the opposite side of UEA2 and discontinuously formed along the outer convex ridge 332. Figure 5A , Figure 5BBy providing multiple longitudinal long recesses 352, 362 and transverse long recesses 353, 363 between the gas flow paths PAa, PAc and the outer convex ridge 332, not only can the drainage performance of the retained water be improved, but the bypass flow of the reaction gas can also be effectively suppressed.

[0148] (3) The bypass flow path forming section also has a plurality of bulges 354, 364 arranged alternately along the outer convex ridge 332 and a plurality of transverse long recesses 353, 363. Figure 5A , Figure 5B The depth (protrusion towards the cooling medium side) of the multiple transversely elongated recesses 353 and 363 is greater than the depth of the multiple bulges 354 and 364. Figure 8 According to this structure, the bulges 354 and 364 can function as throttling parts, thereby improving the suction effect of retained water.

[0149] (4) The plurality of longitudinally elongated recesses 352, 362 are formed in an elongated shape in a manner that intersects with the plurality of transversely elongated recesses 353, 363, and the ends of the plurality of longitudinally elongated recesses 352, 362 have connecting portions 355, 365 that connect with the plurality of transversely elongated recesses 353, 363. Figure 11 Accordingly, the stagnant water in the longitudinal recesses 352 and 362 can be easily discharged along the gas flow of the bypass flow path PAb.

[0150] (5) Multiple longitudinally elongated recesses 352 and 362 extend obliquely toward the flow direction of the reactant gas in the bypass flow path PAb. Figure 11 Accordingly, the stagnant water in the longitudinal recesses 352 and 362 is prone to flow into the bypass flow path PAb, which can promote the discharge of stagnant water from the longitudinal recesses 352 and 362.

[0151] The above-described embodiments can be modified in various ways. Several modifications will be described below. In the above-described embodiments, the bulges 354 and 364 are positioned closer to the gas side than the flat portions 351 and 361, but they can also be positioned on the cooling medium side. That is, the height of the bulges 354 and 364 is higher than the height of the flat portions 351 and 361, but it can also be lower. Alternatively, the bulges 354 and 364 and the flat portions 351 and 361 can be set to the same height. In the above-described embodiments ( Figure 6 , Figure 7In this embodiment, for ease of explanation, the electrolyte membrane 23 is shown positioned at the center of its thickness in the front-rear direction of the power generation unit 1. However, the electrolyte membrane 23 can also be positioned offset from the center in the front-rear direction (e.g., forward). In this case, the depth (front-rear length) of the anode flow path PAa is shallower than the depth of the cathode flow path PAc. In the above embodiment, a plurality of longitudinally elongated recesses 352, 362 and a plurality of transversely elongated recesses 353, 363 are included in the bypass suppression portions 350, 360. However, the plurality of transversely elongated recesses 353, 363 can also be included in a bypass flow path forming portion different from the bypass suppression portions 350, 360.

[0152] In the above embodiment, the UEA2, which is a membrane electrode structure, is formed by integrating the MEA20 and the frame 21. The MEA20 includes an electrolyte membrane 23, an anode electrode 24 as a first electrode, and a cathode electrode 25 as a second electrode. The frame 21 serves as a frame component supporting the outer edges 242a and 252a of the MEA20. However, the structures of the electrolyte membrane 23, the anode electrode 24, and the cathode electrode 25 (such as the positional relationship of their outer edges) are not limited to the structures described above. In the above embodiment, the frame component is formed by a pair of frames 21F and 21R, but it may also be formed by a single frame 21.

[0153] In the above embodiment, the partition 3 is configured such that gas flow paths PAa and PAc (recesses 32) for the flow of reactant gas are formed between the rear surface 2b (first surface) of UEA2 and the front plate 3F (first partition), and between the front surface 2a (second surface) of UEA2 and the rear plate 3R (second partition), respectively. However, the structure of the partition 3 is not limited to the structure described above. In the above embodiment, an outer protruding ridge 332 and a sealing member 336 are provided as a sealing part at the abutment portion where the outer edge 221 of the frame 21 abuts against the partition 3. However, the structure of the sealing part is not limited to this.

[0154] In the above implementation method ( Figure 10 In the diagram, the front plate 3F has a plurality of longitudinally elongated protrusions 3520 (first protrusions) protruding to the opposite side of the rear surface 2b of the UEA2, and the rear plate 3R has a plurality of longitudinally elongated protrusions 3620 (second protrusions) protruding to the opposite side of the front surface 2a of the UEA2. More specifically, the plurality of longitudinally elongated protrusions 3520 are elongated in shape, extending along a plurality of mutually parallel center lines CLc (first center lines) extending in the front-rear direction with a predetermined width Wc (first width) in the left-right direction, and the plurality of longitudinally elongated protrusions 3620 are elongated in shape, extending along a plurality of mutually parallel center lines CLa (second center lines) extending in the front-rear direction with a predetermined width Wa (second width) in the left-right direction. Here, the structure of the partition 3 can be any structure, as long as it appears in the top view viewed from the front-rear direction. Figure 5A , 5B In the diagram, the center lines CLc and CLa are approximately parallel to each other, and the width Wc is narrower than the width Wa. The width Wa can also be narrower than the width Wc.

[0155] In the above implementation method ( Figure 6 In the above embodiment, the front plate 3F also has a plurality of transversely elongated protrusions 3530 (third protrusions) that protrude toward the opposite side of the rear surface 2b of the UEA2 between a plurality of longitudinally elongated protrusions 3520 and the outer convex ridges 332, and the rear plate 3R also has a plurality of transversely elongated protrusions 3630 (fourth protrusions) that protrude toward the opposite side of the front surface 2a of the UEA2 between a plurality of longitudinally elongated protrusions 3620 and the outer convex ridges 332, but these transversely elongated protrusions 3530, 3630 can be omitted. Figure 4 In the above, the cathode flow path PAc (first gas flow path) and the anode flow path PAa (second gas flow path) are wavy when viewed from above and are formed in opposite phases. However, the structure of the first flow path and the second flow path is not limited to the above structure. For example, they can also be formed in a straight line.

[0156] In the above embodiments, an example of applying the fuel cell stack 100 to a vehicle was described. However, the fuel cell stack with the power generation unit of the present invention can be applied not only to mobile bodies other than vehicles such as aircraft and ships and robots, but also to various industrial machinery.

[0157] The above description is merely one example, and the present invention is not limited to the above embodiments and modifications as long as it does not impair the characteristics of the invention. The above embodiments and one or more modifications can be arbitrarily combined, and modifications can be combined with each other.

[0158] Explanation of reference numerals in the attached figures

[0159] 1: Power generation unit; 2: Integrated electrode assembly; 2a: Front surface; 2b: Rear surface; 3: Separator; 3F: Front plate; 3R: Rear plate; 20: Membrane electrode assembly; 21: Frame; 23: Electrolyte membrane; 24: Anode electrode; 25: Cathode electrode; 32: Recess; 100: Fuel cell stack; 242, 252: Gas diffusion layer; 332: Outer convex ridge; 336: Seal; 352, 362: Longitudinal long recess; 353, 363: Lateral long recess; 3520, 3620: Longitudinal long convex; 3530, 3630: Lateral long convex; PAa: Anode flow path; PAc: Cathode flow path; Wa, Wc: Width; CLa, CLc: Centerline.

Claims

1. A power generation unit, characterized in that, It has a membrane electrode structure, a first septum, and a second septum, wherein, The membrane electrode structure is constructed by integrating a membrane electrode assembly and a frame component. The membrane electrode assembly has an electrolyte membrane and a first electrode and a second electrode respectively disposed on two surfaces of the electrolyte membrane. The frame component supports the outer edge of the membrane electrode assembly. The first partition and the second partition are respectively disposed opposite to the first surface and the second surface on the opposite side of the first surface of the membrane electrode structure, forming gas flow paths for the flow of reactive gas between the first electrode and the second electrode. The first septum has a plurality of first protrusions disposed along the outer edge of the membrane electrode structure and protruding toward the opposite side of the first surface. The second partition has a plurality of second protrusions disposed along the outer edge of the membrane electrode structure and protruding toward the opposite side of the second surface. The plurality of first protrusions are elongated in shape, extending along a plurality of mutually parallel first center lines, each with a first width orthogonal to the plurality of first center lines. The plurality of second protrusions are elongated in shape, extending along a plurality of mutually parallel second center lines, each with a second width orthogonal to the plurality of second center lines. In a top view taken from a direction perpendicular to the first surface, the first center line and the second center line are approximately parallel to each other, and the first width is narrower than the second width.

2. The power generation unit according to claim 1, characterized in that, The first partition is a cathode partition that forms a cathode flow path for the flow of oxidant gas between itself and the first electrode. The second partition is an anode partition that forms an anode flow path for fuel gas flow between itself and the second electrode.

3. The power generation unit according to claim 1 or 2, characterized in that, A sealing portion is provided at the contact point where the outer edge of the frame component abuts against the first partition plate and the second partition plate to prevent leakage of the reaction gas. The first partition plate, between the plurality of first protrusions and the sealing portion, also has a plurality of third protrusions protruding to the opposite side of the first surface. The second partition plate, between the plurality of second protrusions and the sealing portion, also has a plurality of fourth protrusions protruding to the opposite side of the second surface. Each of the third protrusions and each of the fourth protrusions extends elongatedly in a direction substantially orthogonal to the first center line and the second center line.

4. The power generation unit according to claim 1 or 2, characterized in that, The first centerline and the second centerline extend in a direction that is approximately orthogonal to the flow direction of the reactant gas along the gas flow path.

5. The power generation unit according to claim 1 or 2, characterized in that, The gas flow path includes a first gas flow path and a second gas flow path. The first gas flow path and the second gas flow path are respectively formed in a wavy shape in the top view and are opposite in phase to each other.

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