Fuel cell stack

Abstract

This fuel cell stack comprises: a laminate formed by alternately laminating a membrane electrode structure and a separator in a prescribed direction; and a positioning member extending in the prescribed direction along an edge of the laminate. An edge part of the separator has, at a corner at which a pair of sides of the separator intersect, an engagement recess part recessed toward the center of the separator so as to engage the positioning member, and a pair of protruding parts formed on both sides of the engagement recess part. The pair of protruding parts have chamfered sections at the leading ends, and rib sections extending along the edges of the pair of protruding parts through the chamfered sections.

Description

Fuel cell stack

[0001] The present invention relates to a fuel cell stack including a laminate of a plurality of power generation cells.

[0002] In recent years, technological development has been carried out for fuel cells that contribute to energy efficiency, in order to enable more people to secure access to affordable, reliable, sustainable and advanced energy. As a technology related to a fuel cell stack used for this type of fuel cell, there has been conventionally known a technology in which a guide bar is erected on a mounting table, and power generation cells are stacked on the mounting table to form a laminate while engaging a recess provided at an edge of the power generation cell with the guide bar (see, for example, Patent Document 1). In the fuel cell stack described in Patent Document 1, a recess provided at an edge of a separator is engaged with the guide bar to form a laminate.

[0003] Japanese Patent Application Laid-Open No.2022-132847

[0004] However, for example, when a recess is provided at a corner of a separator, an acute portion is formed continuously with the recess, so there is a risk that the corner of the separator may be damaged by impact when the separator is conveyed or the like.

[0005] A fuel cell stack that is one aspect of the present invention includes: a laminate configured by alternately laminating membrane electrode assemblies including an electrolyte membrane and an electrode, and separators in a predetermined direction; and a positioning member extending in the predetermined direction along an edge of the laminate. An edge of the separator includes, at a corner where a pair of sides of the separator intersect, an engagement recess recessed toward a central portion of the separator so as to engage with the positioning member, and a pair of protruding portions formed on both sides of the engagement recess, and each of the pair of protruding portions includes a chamfered portion at a tip end, and a rib portion extending along an edge of each of the pair of protruding portions via the chamfered portion.

[0006] According to the present invention, damage to the corner of the separator provided with the engagement recess can be prevented.

[0007] A perspective view schematically showing the overall configuration of a fuel cell stack according to an embodiment of the present invention. A cross-sectional view showing the main components of the cell stack in Figure 1. A perspective view schematically showing the configuration of the integrated electrode assembly incorporated into the fuel cell stack in Figure 1. A cross-sectional view along the line IV-IV in Figure 1. A rear view of the type A separator incorporated into the fuel cell stack in Figure 1. A rear view of the type B separator incorporated into the fuel cell stack in Figure 1. An enlarged view of section VIA in Figure 5A. An enlarged view of section VIB in Figure 5B. An enlarged view of section VII in Figure 6B. A cross-sectional view along the line VIII-VIII in Figure 7.

[0008] Embodiments of the present invention will be described below with reference to Figures 1 to 8. The fuel cell stack according to the embodiment of the present invention is the main component of the fuel cell and constitutes the body of the fuel cell. The fuel cell can be mounted on a vehicle, for example, and generate electricity for driving the vehicle. The fuel cell can also be mounted on mobile devices other than vehicles, such as aircraft and ships, as well as robots and various industrial machines.

[0009] First, the overall configuration of the fuel cell stack will be described in general terms. Figure 1 is a perspective view showing a schematic overall configuration of a fuel cell stack 100 according to an embodiment of the present invention. For convenience, the three mutually orthogonal axial directions shown in the figure will be defined as the front-rear direction, the left-right direction, and the up-down direction, and the configuration of each part will be described according to this definition. These directions are not necessarily the same as the front-rear direction, left-right direction, and up-down direction of a vehicle. The front-rear direction in Figure 1 is the stacking direction of the fuel cell stack 100, and when assembling the fuel cell stack 100, the stacking direction is aligned with the direction of gravity.

[0010] As shown in Figure 1, the fuel cell stack 100 comprises a cell stack 10, end units 40 positioned at both the front and rear ends of the cell stack 10, and a case 30 positioned around the cell stack 10, and the overall structure is substantially rectangular. The case 30 and the end units 40 constitute a housing that encloses the cell stack 10. The length of the fuel cell stack 100 in the left-right direction is longer than its length in the up-down direction. Therefore, the left-right direction is the long-length direction, and the up-down direction is the short-length direction.

[0011] The case 30 has four substantially rectangular side walls 300 facing the top, right, bottom, and left sides of the cell stack 10, respectively. These four side walls 300 form a substantially box-shaped storage space SP0 with the front and rear sides open. The case 30 is made of a metal such as aluminum or iron.

[0012] During the assembly of the fuel cell stack 100, for example, the rear end unit 40 is laid on its side, and the case 30 is fastened to the rear end unit 40. Furthermore, within the case, multiple power generation cells 1 are stacked on top of the rear end unit 40 to assemble a cell stack 10, and then the front end unit 40 is mounted on top of the cell stack 10.

[0013] Multiple guide members 51 (only partially shown) are interposed between the cell laminate 10 and the side wall 300 of the case 30. The guide members 51 are rod-shaped members that extend in the front-rear direction. The front and rear ends of the guide members 51 are supported by the front and rear end units 40.

[0014] Part A of Figure 1 shows a section of the side wall 300 of the case 30 that has been cut away. As shown in Part A of Figure 1, the cell stack 10 is constructed by stacking multiple power generation cells 1 (for convenience, only a single cell 1 is shown) in the housing space SP0 in the front-to-back direction (up-to-down direction during assembly) while being guided by a guide member 51.

[0015] The power generation cell 1 comprises a unitized electrode assembly (UEA) 2 and separators 3 positioned on both the front and rear sides of the UEA 2, which sandwich the UEA 2. The UEA 2 is sometimes referred to as a membrane electrode structure.

[0016] The separator 3 has two types of separators 31 and 32, each having a different shape in part of its outer edge. These two types of separators 31 and 32 are called type A separator 31 and type B separator 32. The UEA 2 and the separator 3 are arranged alternately in the front-to-back direction. In this case, type A separator 31 and type B separator 32 are arranged alternately in the front-to-back direction via the UEA 2. That is, they are arranged in the order of type A separator 31, UEA 2, type B separator 32, UEA 2, type A separator 31, ... In the following, with respect to an arbitrary UEA 2, the separator 3 arranged facing the front of the UEA 2 is defined as type A separator 31, and the separator 3 arranged facing the rear of the UEA 2 is defined as type B separator 32.

[0017] Figure 2 is a cross-sectional view showing the main components of the cell laminate 10. As shown in Figure 2, the separator 3 has a front plate 3F and a rear plate 3R, which are a pair of thin metal plates with a corrugated cross-section. The front plate 3F extends in the vertical, horizontal, and vertical directions and has a front surface 3Fa and a rear surface 3Fb. The rear plate 3R extends in the vertical, horizontal, and vertical directions and has a front surface 3Ra and a rear surface 3Rb. The rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R, which face each other, are joined at their outer edges by welding or the like. In this way, the front plate 3F and the rear plate 3R are integrally joined, and the separator 3 is formed. The separator 3 is made of a conductive material with excellent corrosion resistance, such as stainless steel, titanium, or titanium alloy.

[0018] Inside the separator 3, which is enclosed by the front plate 3F and the rear plate 3R, a cooling channel PAw is formed between the rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R, through which a cooling medium flows. The power generation surface of the power generation cell 1 is cooled by the flow of the cooling medium. For example, water can be used as the cooling medium. The surfaces of the separator 3 facing the UEA 2 (front surface 3Fa and rear surface 3Rb) are formed to be uneven by press molding or the like so as to form a gas channel between them and the UEA 2.

[0019] More specifically, an anode channel PAa is formed between the front surface 2a of the UEA2 and the rear plate 3R of the separator 3 facing the front surface 2a, through which a hydrogen-containing fuel gas flows. A cathode channel PAc is formed between the rear surface 2b of the UEA2 and the front plate 3F of the separator 3 facing the rear surface 2b, through which an oxygen-containing oxidizer gas flows. The fuel gas and oxidizer gas are sometimes referred to collectively as reaction gases without distinction. A compressive load F is applied to the cell stack 10 in the front-rear direction during the assembly of the fuel cell stack 100, and this compressive load F is maintained after the assembly of the fuel cell stack 100 is completed.

[0020] Figure 3 is a perspective view showing the schematic configuration of the UEA2. As shown in Figure 3, the UEA2 comprises a membrane electrode assembly (MEA) 20 and a frame 21.

[0021] The MEA20 comprises an electrolyte membrane, an anode electrode provided on the front surface of the electrolyte membrane, and a cathode electrode provided on the rear surface of the electrolyte membrane. The electrolyte membrane is, for example, a solid polymer electrolyte membrane. The anode electrode has an electrode catalyst layer formed on the front surface of the electrolyte membrane, which serves as the reaction field for the electrode reaction, and a gas diffusion layer provided on the front surface of the electrode catalyst layer, which diffuses and supplies fuel gas. The cathode electrode has an electrode catalyst layer formed on the rear surface of the electrolyte membrane, which serves as the reaction field for the electrode reaction, and a gas diffusion layer provided on the rear surface of the electrode catalyst layer, which diffuses and supplies oxidizing gas.

[0022] At the anode electrode, fuel gas (hydrogen) supplied through the anode channel PAa (Figure 2) and gas diffusion layer is ionized by the action of a catalyst and moves to the cathode electrode side through the electrolyte membrane. The electrons generated at this time pass through an external circuit and are extracted as electrical energy. At the cathode electrode, oxidizing gas (oxygen) supplied through the cathode channel PAc (Figure 2) and gas diffusion layer reacts with hydrogen ions introduced from the anode electrode and electrons that have moved from the anode electrode to produce water. The generated water provides appropriate humidity to the electrolyte membrane, and excess water is discharged to the outside of UEA2.

[0023] The frame 21 is a thin, rectangular film or sheet member made of an insulating resin, rubber, or the like. The frame 21 can also be called a film or a sheet. A roughly rectangular opening 21a is provided in the center of the frame 21. The MEA 20 is provided so as to cover the entire opening 21a, and the outer edge of the MEA 20 is supported by the frame 21. To the left of the opening 21a of the frame 21, three through holes 201 to 203 are opened vertically, penetrating the frame 21 in the front-to-back direction. To the right of the opening 21a, three through holes 204 to 206 are opened vertically, penetrating the frame 21 in the front-to-back direction.

[0024] Figure 4 is a cross-sectional view (a cross-sectional view along the line IV-IV in Figure 1) showing the main components of the fuel cell stack 100. Figure 4 includes a rear view of the type A separator 31 facing the front surface 2a of the UEA 2. The type A separator 31 and the type B separator 32 are constructed to be the same shape except for a part of the outer edge. Therefore, the general configuration of the separator 3 will be explained using Figure 4. Figure 4 shows the center point P, which is the midpoint of the separator 3 in both the left-right and up-down directions. Hereafter, the side facing the center point P will be called the inside of the separator 3, and the side radiating away from the center point P will be called the outside of the separator 3.

[0025] As shown in Figure 4, a corrugated anode channel PAa (Figure 2) is formed in the central part of the rear surface 3Rb of the separator 3 in the vertical and horizontal directions, facing the front surface 2a of the MEA 20 (partially omitted from the illustration). Although omitted from the illustration, a corrugated cathode channel PAc (Figure 2) is formed in the central part of the front surface 3Fa of the separator 3 in the vertical and horizontal directions, facing the rear surface 2b of the MEA 20.

[0026] The separator 3 has through holes 301 to 306 that penetrate the separator 3 in the front-to-back direction, at positions corresponding to the through holes 201 to 206 (Figure 3) of the frame 21. The through holes 301 to 306 communicate with the through holes 201 to 206 of the frame 21, respectively. The collection of these interconnected through holes 201 to 206 and 301 to 306 forms multiple flow channels that penetrate the cell stack 10 and extend in the front-to-back direction.

[0027] Although not shown in the diagram, the rear surface 3Rb of the separator 3 is provided with a sealing portion that protrudes backward to seal off the leakage of fuel gas from the anode flow path PAa. The sealing portion allows communication between the through holes 301 and 306 and the anode flow path PAa, while preventing communication between the other through holes 302 to 305 and the anode flow path PAa. Similarly, the front surface 3Fa of the separator 3 is provided with a sealing portion that protrudes forward to seal off the leakage of oxidizer gas from the cathode flow path PAc. The sealing portion allows communication between the through holes 303 and 304 and the cathode flow path PAc, while preventing communication between the other through holes 301, 302, 305, and 306 and the cathode flow path PAc.

[0028] As shown in Figure 1, the rear end unit 40 has multiple through holes 401 to 406 that penetrate the end unit 40 in the front-to-back direction, at positions corresponding to the through holes 201 to 206 of the UEA 2 (Figure 2) and the through holes 301 to 306 of the separator 3 (Figure 3). The front end unit 40 does not have through holes 401 to 406.

[0029] Fuel gas is supplied to the fuel cell stack 100 through the through-hole 401, as shown by the solid arrow. This fuel gas is guided to the anode flow path PAa through the through-holes 201 and 301. After passing through the anode flow path PAa, the fuel gas is discharged from the through-hole 406 through the through-holes 206 and 306, as shown by the solid arrow.

[0030] As shown by the dotted arrow, an oxidizer gas is supplied to the fuel cell stack 100 through the through-hole 404. This oxidizer gas is guided to the cathode channel PAc through the through-holes 204 and 304. After passing through the cathode channel PAc, the oxidizer gas is discharged from the through-hole 403 through the through-holes 203 and 303, as shown by the dotted arrow.

[0031] Cooling medium is supplied to the fuel cell stack 100 through the through-hole 405, as shown by the dashed-dotted arrow. This cooling medium is guided to the cooling channel PAw through the through-holes 205 and 305. After passing through the cooling channel PAw, the cooling medium is discharged from the through-hole 402 through the through-holes 202 and 302, as shown by the dashed-dotted arrow.

[0032] As shown in Figure 4, impact receiving members 45 are positioned between the inner surface 30a of the case 30 and the outer surface 10a of the cell laminate 10. Specifically, if the four sides of the separator 3 are defined as the top side 311, the right side 312, the bottom side 313, and the left side 314, then a pair of impact receiving members 45 are positioned in the space between the top side 311 and the inner surface 30a of the case, the space between the right side 312 and the inner surface 30a of the case, the space between the bottom side 313 and the inner surface 30a of the case, and the space between the left side 314 and the inner surface 30a of the case. The pair of impact receiving members 45 are provided near the corners of the cell laminate 10. In other words, a pair of impact receiving members 45 are positioned near each of the four corners of the cell laminate 10, sandwiching each corner.

[0033] The impact receiving member 45 has a substantially rectangular cross-section and extends almost the entire length of the cell stack 10 in the front-to-back direction. The impact receiving member 45 is made of an elastic material such as resin or rubber and is composed of an insulator. The impact receiving member 45 is fixed to the inner surface 30a of the case in advance. By providing the impact receiving member 45 near the corners of the cell stack 10, when an impact is applied to the case 30 from the outside in a direction perpendicular to the stacking direction of the cell stack 10, the area near the corners of the cell stack 10 will come into contact with the impact receiving member 45 due to inertial force. This effectively suppresses displacement of the power generation cells 1. There is a predetermined gap between the cell stack 10 and the impact receiving member 45 (see Figure 6A). For this reason, the impact receiving member 45 does not have a positioning function when the power generation cells 1 are stacked.

[0034] The fuel cell stack 100 is constructed by stacking power generation cells 1 while positioning them via a positioning unit. The UEA 2 is pre-integrated with the separator 3 by welding or the like. Therefore, a positioning unit is not required for the UEA 2. Alternatively, the UEA 2 may be stacked alternately without being integrated with the separator 3. The configuration of the positioning unit for positioning the separator 3 will be described below.

[0035] The positioning section includes long-side recesses 501 and 502 provided in the left-right center of the long sides of the separator 3, i.e., the upper side 311 and the lower side 313; short-side recesses 503 and 504 provided in the vertical center of the short sides of the separator 3, i.e., the right side 312 and the left side 314; and corner recesses 505 and 506 provided in the lower right corner 315 where the right side 312 and the lower side 313 intersect, and the upper left corner 316 where the upper side 311 and the left side 314 intersect.

[0036] The upper edge 311 and lower edge 313 are provided with bulging portions 317 and 318 at their left-right centers, respectively, which bulge upward and downward. The long-side recesses 501 and 502 are provided in the bulging portions 317 and 318, respectively. Multiple guide members 51 are arranged corresponding to multiple positioning portions. The multiple guide members 51 are all the same shape, and their cross-sectional shape is consistent from the lower end (rear end in Figure 1) to the upper end (front end in Figure 1). The cross-sectional shape of the guide member 51 is circular with a predetermined outer diameter. The lower and upper ends of the multiple guide members 51 are fitted into recesses or through holes provided in the end unit 40, thereby positioning the guide members 51 in predetermined positions within the case.

[0037] Figures 5A and 5B are rear views of type A separator 31 and type B separator 32, respectively. In Figures 5A and 5B, for convenience, the positioning portions (recesses 501 to 506) on the outer edge of the separator 3 are exaggerated together with the guide member 51, while other components of the separator 3 (through holes 301 to 306, etc.) are omitted from the illustration.

[0038] As shown in Figure 5A, the A-type separator 31 is provided with three positioning parts: a long-side recess 501 on the upper side 311, a short-side recess 504 on the left side 314, and a corner recess 505 on the lower right corner 315. These recesses 501, 504, and 505 extend inward from the outer edge of the A-type separator 31 with a predetermined width W1. Specifically, the long-side recess 501 is recessed in a slit shape (approximately U-shape) from the center position in the left-right direction of the upper side 311 toward the center point P below. The short-side recess 504 is recessed in a slit shape (approximately U-shape) from the center position in the vertical direction of the left side 314 toward the center point P to the right. The corner recess 505 is recessed in a slit shape (approximately U-shape) from the lower right corner 315 toward the center point P in the upper left.

[0039] The width W1 of the recesses 501, 504, and 505 is slightly larger than the outer diameter D0 of the guide member 51, and the guide member 51 is engaged (inserted) into the recesses 501, 504, and 505, respectively. The long side recess 501 restricts the left-right position of the A-type separator 31. The short side recess 504 restricts the up-down position. The corner recess 505 restricts the rotational movement of the A-type separator 31. The long side recess 501 may be located to the right or left of the left-right center position of the upper side 311. The short side recess 504 may be located above or below the up-down center position of the left side 314.

[0040] A wide, roughly U-shaped recess 512 is provided in the center of the lower edge 313 of the A-type separator 31, directed toward the center point P. A wide, roughly U-shaped recess 513 is provided in the center of the right edge 312, directed toward the center point P. The widths W2 of the wide recesses 512 and 513 are equal and larger than the widths W1 of the positioning recesses 501, 504, and 505. Therefore, there is a gap between the wide recesses 512 and 513 and the guide member 51, extending around the entire circumference of the guide member 51. A notch 515 is provided in the upper left corner 316 of the A-type separator 31, spaced inward from the guide member 51 and cut out in a roughly L-shape.

[0041] As shown in Figure 5B, the B-type separator 32 is provided with three positioning parts different from those of the A-type separator 31: a long-side recess 502 on the lower edge 313, a short-side recess 503 on the right edge 312, and a corner recess 506 on the upper left corner 316. These recesses 502, 503, and 506 each extend inward from the outer edge of the B-type separator 32 while maintaining a predetermined width W1. Specifically, the long-side recess 502 is recessed in a slit shape (approximately U-shape) from the center position in the left-right direction of the lower edge 313 toward the upper center point P. The short-side recess 503 is recessed in a slit shape (approximately U-shape) from the center position in the vertical direction of the right edge 312 toward the left center point P. The corner recess 506 is recessed in a slit shape (approximately U-shape) from the upper left corner 316 toward the lower right center point P.

[0042] The width W1 of the recesses 502, 503, and 506 is slightly larger than the outer diameter D0 of the guide member 51, and the guide member 51 is engaged (inserted) into the recesses 502, 503, and 506, respectively. The long side recess 502 restricts the left-right position of the B-type separator 32. The short side recess 503 restricts the up-down position. The corner recess 506 restricts the rotational movement of the B-type separator 32. The long side recess 502 may be located to the left or right of the left-right center position of the bottom side 313. The short side recess 503 may be located below or above the up-down center position of the right side 312.

[0043] A roughly U-shaped wide recess 511 is provided in the vertical center of the upper edge 311 of the B-type separator 32, directed toward the center point P. A roughly U-shaped wide recess 514 is provided in the horizontal center of the left edge 314, directed toward the center point P. The widths W2 of the wide recesses 511 and 514 are equal to each other and are larger than the widths W1 of the positioning recesses 502, 503, and 506. Therefore, there is a gap between the wide recesses 511 and 514 and the guide member 51, extending around the entire circumference of the guide member 51. A roughly L-shaped notch 516 is provided at the lower right corner 315 of the B-type separator 32, spaced inward from the guide member 51.

[0044] As described above, the positioning recesses 501, 504, 505 of the A-type separator 31 and the positioning recesses 502, 503, 506 of the B-type separator 32 all extend radially outward from the center point P. Therefore, when the cell stack 10 is pressed during assembly of the fuel cell stack 100, the recesses 501, 504, 505 of the A-type separator 31 and the recesses 502, 503, 506 of the B-type separator 32 can be displaced outward while their positions are regulated by the guide member 51.

[0045] At this time, the wide recesses 512, 513 of the A-type separator 31 and the wide recesses 511, 514 of the B-type separator 32 have a large gap with the guide member 51, so they can be displaced outward without interfering with the guide member 51. In addition, notches 515, 516 are provided in the upper left corner 316 of the A-type separator 31 and the lower right corner 315 of the B-type separator 32, so these corners 316, 315 can be displaced outward without interfering with the guide member 51. Accordingly, when a pressing force acts on the cell laminate 10, the outer edge of the separator 3 can be smoothly spread outward. Therefore, the cell laminate 10 can be configured in a state where the power generation cells 1 are accurately positioned without damaging the separators 3.

[0046] In particular, the positioning of the A-type separator 31 is performed by the recess 505 provided in the lower right corner 315 and the recesses 501, 504 provided in the upper side 311 and the left side 314 extending opposite to the lower right corner 315. Further, the positioning of the B-type separator 32 is performed by the recess 506 provided in the upper left corner 316 and the recesses 502, 503 provided in the lower side 313 and the right side 312 extending opposite to the upper left corner 316.

[0047] The recesses 501 and 504 are provided at positions that substantially trisect the entire length of the outer edge of the A-type separator 31 starting from the recess 505 at the lower right corner 315. The recesses 502 and 503 are provided at positions that substantially trisect the entire length of the outer edge of the B-type separator 32 starting from the recess 506 at the upper left corner 316. Accordingly, the outer edges of the A-type separator 31 and the B-type separator 32 are evenly positioned in the circumferential direction at three points respectively. For this reason, it is possible to prevent the positioning recesses 501 to 506 from being caught on the guide member 51, which would cause the separators 31 and 32 to be stacked in an inclined state.

[0048] The A-type separators 31 and the B-type separators 32 are alternately stacked via UEA 2, and a resin frame 21 (FIG. 3), which is an insulator, is interposed between the separators 31 and 32 in areas other than the vicinity of the positioning portion. For this reason, the insulation distance between the separators 31 and 32 can be ensured. On the other hand, since positioning is performed by the separators 31 and 32 instead of the frame 21, the frame 21 is not interposed between the separators 31 and 32 in the vicinity of the positioning portion, which may lead to a risk that the insulation distance cannot be ensured.

[0049] In consideration of this point, in the present embodiment, the positioning recesses 501, 504, 505 of the A-type separator 31 and the positioning recesses 502, 503, 506 of the B-type separator 32 are provided on different sides and corners from each other. The width W2 of the wide recesses 511 and 514 of the B-type separator 32 is set such that they do not overlap with the recesses 501 and 504 of the A-type separator 31 when viewed from the stacking direction. Further, the width W2 of the wide recesses 512 and 513 of the A-type separator 31 is set such that they overlap with the recesses 502 and 503 of the B-type separator 32 when viewed from the stacking direction.

[0050] Furthermore, the corners 315 of the B-type separator 32 are cut to form notches 516, and the corners of the A-type separator 31 are cut to form notches 515. As a result, the recesses 501, 504, and 505 of the A-type separator 31 and the outer edges of the B-type separator 32 do not overlap in a plan view from the stacking direction of the cell laminate 10, i.e., the thickness direction (front-to-back direction) of the separator 3, and the recesses 502, 503, and 506 of the B-type separator 32 and the outer edges of the A-type separator 31 do not overlap in a plan view. This ensures a sufficient insulation distance between the separators 31 and 32 in the vicinity of the positioning recesses 501 to 506.

[0051] The configuration of the corners 315, 316 of the separator 3, which has corner recesses 505, 506 and notches 515, 516, will be described in more detail. Figure 6A is an enlarged view of part VIA in Figure 5A showing the detailed configuration of the upper left corner 316 of type A separator 31, and Figure 6B is an enlarged view of part VIB in Figure 5B showing the detailed configuration of the upper left corner 316 of type B separator 32. Although not shown, the lower right corner 315 of type A separator 31 is configured similarly to the upper left corner 316 of type B separator, and the lower right corner 315 of type B separator 32 is configured similarly to the upper left corner 316 of type A separator 31. Figures 6A and 6B also show the impact receiving members 45 arranged on both sides of the upper left corner 316 of separator 3.

[0052] As shown in Figures 6A and 6B, a double layer of convex bead portions 331 and 332, i.e., metal bead seals protruding to the rear, are provided around the through-hole 301 of the separator 3 to seal the fuel gas. Although not shown in the illustration, the inner bead portion 331 surrounds the through-hole 301 for fuel gas supply (Figure 4), and the outer bead portion 332 surrounds the area from the through-hole 301 for fuel gas supply to the through-hole 304 for oxidizer gas supply, the through-hole 306 for fuel gas discharge, and the through-hole 303 for oxidizer gas discharge, that is, the entire region through which the reaction gas flows.

[0053] As shown in Figure 6B, the corner recess 506 has a pair of side surfaces 506a, 506a that face each other and extend substantially parallel to one another, and a substantially arc-shaped bottom surface 506b that connects the pair of side surfaces 506a, 506a. On both sides of the corner recess 506, a pair of protrusions 52 are formed, sandwiched between the side surfaces 506a and the outer edge 33. At the tip of the protrusion 52, a chamfered portion 520 is provided, which is beveled at an angle along a reference line RL1 that intersects the extension of the outer edge 33 at a predetermined angle (for example, 45°). The extension of the side surface 506a and the extension of the outer edge 33 intersect at an acute angle, but by chamfering the tip of the protrusion 52, the acute-angled portion at the tip of the protrusion 52 is removed.

[0054] The chamfered portion 520 is provided such that the center P1 of the guide member 51 is located inside the reference line RL1, with a gap between the guide member 51 and the bottom surface 506b of the corner recess 506. The region near the outer edge of the separator 3, that is, the region between the outer edge 33 and the bead portion 332, is called the outer edge portion 34. In particular, the outer edge portion 34 along the upper edge 311 of the separator 3 to the right of the upper left corner portion 316 is called the upper outer edge portion 34U, and the outer edge portion 34 along the left edge 314 of the separator 3 below the upper left corner portion 316 is called the left outer edge portion 34L.

[0055] The outer edge 33 of the upper outer edge portion 34U of the B-type separator 32 is cut by punching out a predetermined width W1 from the outer edge 33 in a predetermined length range (referred to as the second range) AR2 that exceeds a predetermined length range (referred to as the first range) AR1 from the left end of the outer edge 33, thereby forming a recess 382. The outer edge 33 of the left outer edge portion 34L of the B-type separator 32 is cut by punching out a predetermined width W1 from the outer edge 33 in a predetermined length range (referred to as the fourth range) AR4 that exceeds a predetermined length range (referred to as the third range) AR3 from the upper end of the outer edge 33, thereby forming a recess 384.

[0056] In the first range AR1 and the third range AR3 of the B-type separator 32, the outer edge 33 is not cut, and in these ranges AR1 and AR3, the outer edge 33 becomes a convex portion 391, 393. As a result, the pair of outer edges 33, 33 of the B-type separator 32 that sandwich the corner recess 506, i.e., the upper edge 311 and the left edge 314, are formed in an uneven shape.

[0057] A predetermined gap GP1 is provided in the left-right direction between the protrusion 391 of the B-type separator 32 and the impact receiving member 45 facing the protrusion 391. A predetermined gap GP2 is provided in the up-down direction between the protrusion 393 of the B-type separator 32 and the impact receiving member 45 facing the protrusion 393. The widths of gap GP1 and gap GP2 may be the same or different. In this state, when no external impact is applied to the case 30, there are predetermined gaps GP1 and GP2 between the separator 3 and the impact receiving member 45. For this reason, the impact receiving member 45 does not have a positioning function during the assembly of the fuel cell stack 100.

[0058] Ribs 35 are provided on the outer edge 34 near the upper left corner 316 of the B-type separator 32, more specifically on the outer edge 34 in a predetermined range AR1 to AR4, projecting forward and backward from the front plate 3F and the rear plate 3R, respectively. The ribs 35 include an inner rib 350 that extends seamlessly in the vertical and horizontal directions along the outer edge 33 of the separator 3, an outer rib 360 that extends outside the inner rib 350 and substantially parallel to the inner rib 350, and a plurality of intermediate ribs 370 provided between the inner rib 350 and the outer rib 360. The widths W2 of the inner rib 350, the outer rib 360, and the intermediate ribs 370 are equal to each other and constant along their entire length.

[0059] Figure 7 is an enlarged view of section VII of Figure 6B. As shown in Figure 7, the inner rib 350 has a plurality of main rib portions 351 extending substantially parallel to the outer edge 33 and a plurality of sub-rib portions 352 extending in a direction perpendicular to the outer edge 33. More specifically, the sub-rib portions 352 are provided so as to protrude inward (towards the through hole 301) from the main rib portions 351 when viewed from the stacking direction. The inner ends of a pair of sub-rib portions 352 are bent in a substantially arc shape and connected to each other at a bent portion 353. The main rib portions 351 and the sub-rib portions 352 are provided alternately over a predetermined range AR1 to AR4 in Figure 6B.

[0060] In other words, the inner rib 350 has alternating rib protrusions (main rib portion 351) that project outward and rib recesses (bent portion 353) that are recessed inward along the outer edge 33, and extends in an uneven manner when viewed from the stacking direction. The inner rib 350 may extend in a zigzag pattern or a wavy pattern when viewed from the stacking direction. In this case as well, it will have alternating recesses and protrusions, resulting in an uneven shape. The inner rib 350 has an inclined rib 355 that extends diagonally inside the chamfered portion 520, approximately parallel to the chamfered portion 520. The inner rib 350 extends seamlessly from the upper outer edge 34U to the left outer edge 34L via the inclined rib 355 inside the chamfered portion.

[0061] The outer rib 360 has a plurality of main rib portions 361 extending substantially parallel to the outer edge 33 and a plurality of sub-rib portions 362 extending perpendicular to the outer edge 33. More specifically, the sub-rib portions 362 are provided so as to project outward (towards the outer edge 33) from the main rib portions 361 when viewed from the stacking direction, and the outer ends of a pair of sub-rib portions 362 are bent in a substantially arc shape and connected to each other at a bent portion 363. The main rib portions 361 and the sub-rib portions 362 are provided alternately over a predetermined range AR1 to AR4 in Figure 6B. Therefore, the outer rib 360 extends in an uneven manner when viewed from the stacking direction, similar to the inner rib 350.

[0062] Welded sections 345 are provided in multiple regions located between the outer rib 360 and the outer edge 33, and enclosed in a roughly U-shape by the main rib section 361 and a pair of sub-rib sections 362, 362. At the welded sections 345, the front plate 3F and the rear plate 3R are joined by laser welding or the like. However, as shown in Figure 6B, in the second range AR2 and the fourth range AR4, the vicinity of the outer edge of the B-type separator 32, including the bent section 363, is cut along with the welded section 345. In this regard, in predetermined ranges AR2 and AR4, the vicinity of the outer edge of the B-type separator 32 may be cut outside the welded section 345.

[0063] The main rib portion 361 of the outer rib 360 and the main rib portion 351 of the inner rib 350 are located at the same position in the left-right direction in the first range AR1 and the second range AR2, and at the same position in the up-down direction in the third range AR3 and the fourth range AR4. Therefore, the main rib portions 351 and 361 face each other with the intermediate rib 370 in between. A welded portion 345 is provided near the outer rib 360 (on the outer edge 33 side), but no welded portion is provided near the inner rib 350 (for example, on the through hole 301 side).

[0064] As shown in Figure 7, the intermediate rib 370 has a pair of main rib portions 371 extending substantially parallel to the outer edge 33 and a pair of sub-rib portions 372 extending in a direction substantially perpendicular to the outer edge 33. More specifically, the sub-rib portions 372 have a substantially semicircular shape, and the intermediate rib 370 as a whole has an oval shape. The length of the main rib portions 371 of the intermediate rib 370 is equal to or approximately equal to the length of the main rib portions 351 and 361 of the inner rib 350 and outer rib 360. The intermediate rib 370 forms an oval closed region AR5. Inside each of the multiple intermediate ribs 370 (closed region AR5), welded portions 346 are provided, and the welded portions 346 are scattered along the outer edge 33. At the welded portions 346, the front plate 3F and the rear plate 3R are joined by laser welding or the like. The welded portions 346 extend substantially parallel to the outer edge 33.

[0065] As shown in Figure 6B, the outer rib 360 has an inclined rib 365 that extends linearly along the chamfered portion 520, a side rib 366 that extends linearly along the side surface 506a of the corner recess 506, and a bottom rib 367 that extends in a substantially arc shape along the bottom surface 506b. The outer rib 360 extends seamlessly from the upper outer edge 34U to the left outer edge 34L via the inclined rib 365, the side rib 366, and the bottom rib 367. The outer rib 360 extends inward (towards the center point P) beyond the intermediate rib 370 along the corner recess 506. Therefore, the intermediate rib 370 is not provided inside the corner recess 506. Although detailed illustrations are omitted, the lower right corner 315 of the A-type separator 31 is configured similarly to the upper left corner 316 of the B-type separator 32.

[0066] In this embodiment, protrusions 52 projecting outward (opposite the center point P) are formed on both sides of the corner recesses 505 and 506 of the separator 3, and chamfered portions 520 are provided at the tips of the protrusions 52. Furthermore, an outer rib 360 is provided seamlessly along the outer edges 33, 33 on both sides of the corner recesses 505 and 506 and along the corner recesses 506. This increases the strength of the corners 315 and 316 of the separator 3 having the corner recesses 505 and 506, and prevents damage to the corners 315 and 316 of the separator 3.

[0067] In other words, since the separator 3 is a thin plate, when the separator 3 is transported or stacked, if the outer edge 33 of the separator 3 comes into contact with an outer member, the outer edge 33 may be damaged. In particular, if the tip of the protrusion 52 is configured at an acute angle, the tip of the protrusion 52 is prone to damage. In this embodiment, a chamfered portion 520 is provided at the tip of the protrusion 52, and an outer rib 360 is provided over the entire area of ​​the corners 315, 316 of the separator 3, thereby improving the strength of the corners 315, 316 and preventing damage to the outer edge 33.

[0068] Furthermore, since the inner rib 350 and outer rib 360 are configured to be uneven when viewed from the thickness direction of the separator 3, the rigidity of the separator 3 can be significantly increased over the entire area near the corners of the separator 3. Moreover, since a plurality of intermediate ribs 370 are provided on the outside of the inner rib 350 along the outer edge 33 of the separator 3, the strength of the outer edge 34 near the corners of the separator 3 can be further increased. As a result, the bending strength of the separator 3 is improved, and the deformation of the outer edge 34 when the separator 3 comes into contact with the impact receiving member 45 can be significantly suppressed.

[0069] On the outside of the outer rib 360, more specifically between the pair of sub-rib portions 362, 362, a welded portion 345 is provided facing the main rib portion 361 (Figure 7). This prevents misalignment of the plates 3F and 3R near the outer rib 360. The intermediate rib 370 is approximately oval in shape, and a welded portion 346 is provided in the closed region AR5 of the intermediate rib 370. This facilitates welding of the plates 3F and 3R together and prevents misalignment of the plates 3F and 3R near the intermediate rib 370. Furthermore, by providing the welded portion 346 in the closed region AR5, the welding area can be easily secured without interfering with the multiple ribs 350, 360, and 370 of the outer edge portion 34. The multiple intermediate ribs 370 are evenly arranged along the outer edge 33 of the separator 3. Therefore, the welded portions 346 are also evenly provided, allowing for good joining of the plates 3F and 3R together over the entire area along the outer edge 33.

[0070] The configuration of the upper left corner 316 of the A-type separator 31 will now be described. In Figure 6A, the outer edge 33 of the B-type separator 32 is shown by a dashed line, and the first range AR1 to the fourth range AR4 are shown in Figure 6B. As shown in Figure 6A, the outer edge 34 of the A-type separator 31 is provided with a rib 35 that has the same shape as the outer edge 34 of the B-type separator 32. Therefore, the outer edge 34 is provided with an inner rib 350, an outer rib 360, and an intermediate rib 370 along the outer edge 33. However, the uneven shape of the outer edge 33 differs between the A-type separator 31 and the B-type separator 32.

[0071] In other words, a notch 515 is formed in the upper left corner 316 of the A-type separator 31, which is cut out larger inward than the corner recess 506. The edge of the notch 515 is located inward from the corner recess 506. The notch 515 is provided on the outside of the intermediate rib 370 so as not to intersect with the intermediate rib 370. More specifically, the edge of the notch 515 is located near the intermediate rib 370 and near the inclined rib 355 of the inner rib 350.

[0072] The upper outer edge portion 34U of the A-type separator 31 is cut by punching out a predetermined width W1 from the outer edge 33 of the A-type separator 31 over the first range AR1, forming a recess 381. The left outer edge portion 34L of the A-type separator 31 is cut by punching out a predetermined width W1 from the outer edge 33 of the A-type separator 31 over the third range AR3, forming a recess 383. On the other hand, in the second range AR2 of the upper outer edge portion 34U and the fourth range AR4 of the left outer edge portion 34L, the outer edge 33 is not cut, and the outer edges 33 in the second range AR2 and the fourth range AR4 become convex portions 392 and 394. As a result, the pair of outer edges 33, 33 of the A-type separator 31 sandwiching the notch portion 515, i.e., the upper edge 311 and the left edge 314, are formed in an uneven shape.

[0073] The protrusions 392 and 394, like the protrusions 391 and 393 of the B-type separator 32, face the impact receiving member 45 with predetermined gaps GP1 and GP2 between them and function as impact receiving parts. The protrusions 391 and 392 are arranged side by side in the left-right direction along the upper edge 311, and the protrusions 393 and 394 are arranged side by side in the up-down direction along the left edge 314. As a result, when an impact acts on the vehicle, the outer edge 33 of the A-type separator 31 and the outer edge 33 of the B-type separator 32 come into contact with the impact receiving member 45 simultaneously, allowing the impact to be absorbed effectively.

[0074] Thus, the outer edge 33 of the A-type separator 31 is cut in the first range AR1 and the third range AR3, which are close to the upper left corner 316, but not in the second range AR2 and the fourth range AR4, which are farther from the upper left corner 316. In contrast, the outer edge 33 of the B-type separator 32 is not cut in the first range AR1 and the third range AR3, but is cut in the second range AR2 and the fourth range AR4. Furthermore, the A-type separator 31 is provided with a notch 515 that is cut inward from the corner recess 506 of the B-type separator 32. For this reason, the outer edge 33 of the upper left corner 316 of the A-type separator 31 and the outer edge 33 of the upper left corner 316 of the B-type separator 32 do not overlap when viewed from the stacking direction.

[0075] Figure 8 is a cross-sectional view of the outer edge 34 in the third range AR3 of separator 3 (a cross-sectional view along the line VIII-VIII in Figure 7). Figure 8 shows a pair of B-type separators 32, 32 and a single A-type separator 31 positioned between the pair of B-type separators 32, 32 via the frame 21 of UEA2.

[0076] As shown in Figure 8, inner ribs 350, outer ribs 360, and intermediate ribs 370 are provided projecting in the front-rear direction from the front plate 3F and rear plate 3R of the separators 31 and 32, respectively. The tip surfaces of these ribs 350, 360, and 370 each abut against the frame 21. As a result, the compressive load F in the front-rear direction (Figure 2) during the assembly of the fuel cell stack 100 presses the separator 3 and the frame 21 together, and the frame 21 is sandwiched between the front and rear separators 31 and 32.

[0077] As shown in Figure 6A, the outer edge 33 of the A-type separator 31 becomes a recess 383 in the third range AR3. Therefore, as shown in Figure 8, the entire outer edge 34 of the A-type separator 31 in the third range AR3 is covered by the frame 21. Although not shown in the figure, similarly in the first range AR1, the entire outer edge 34 of the A-type separator 31 is covered by the frame 21. On the other hand, as shown in Figure 6B, in the second range AR2 and the fourth range AR4, the outer edges 33 of the B-type separator 32 become recesses 382 and 384, and the entire outer edge 34 of the B-type separator 32 in the second range AR2 and the fourth range AR4 is covered by the frame 21. This allows the separators 31 and 32 to be insulated from each other via the frame 21.

[0078] The outer edge portion 34 of the A-type separator 31 has protrusions 392 and 394 in the second range AR2 and the fourth range AR4, and protrudes outward from the frame 21. However, the B-type separator 32 has recesses 382 and 384 in the second range AR2 and the fourth range AR4, so when viewed from the stacking direction (front-to-back direction), the protrusions 392 and 394 do not overlap with the B-type separator 32. Also, the outer edge portion 34 of the B-type separator 32 has protrusions 391 and 393 in the first range AR1 and the third range AR3, and protrudes outward from the frame 21. However, the A-type separator 31 has recesses 381 and 383 in the first range AR1 and the third range AR3, so when viewed from the stacking direction, the protrusions 391 and 393 do not overlap with the A-type separator 31.

[0079] In this way, the recesses 381, 383 and protrusions 392, 394 of the A-type separator 31 are arranged alternately with the recesses 382, ​​384 and protrusions 391, 392 of the B-type separator 32 when viewed from the stacking direction. Therefore, the A-type separator 31 and the B-type separator 32 do not overlap outside the frame 21. As a result, as shown in Figure 8, the distance L between the separators 3, 3 (B-type separators 32, 32 in Figure 8) that face each other outside the frame 21 is increased. Consequently, a sufficient insulation distance can be secured between the separators 3, 3 while the outer edge 33 of the separator 3 is configured to abut against the impact receiving member 45.

[0080] This embodiment provides the following effects: (1) The fuel cell stack 100 comprises a cell stack 10 formed by alternately stacking a UEA 2 including an electrolyte membrane and electrodes, separators 3 (Type A separator 31, Type B separator 32) in the front-rear direction (a predetermined direction), and a guide member 51 extending in the front-rear direction along the outer edge 33 of the cell stack 10 (Figures 1 and 4). The outer edge 34 of the Type B separator 32 has a corner recess 506 formed toward the center point P of the separator 3 at the upper left corner 316 where a pair of sides of the Type B separator 32 (for example, the upper edge 311 and the left edge 314) intersect, so as to engage with the guide member 51, and a pair of protrusions 52, 52 formed on both sides of the corner recess 506 (Figure 6B). Each of the pair of protrusions 52, 52 has a chamfered tip 520 and a rib 35 (rib portion), more specifically an outer rib 360, that extends along the edge of each of the pair of protrusions 52, 52 via the chamfered tip 520 (Figure 6B). The lower right corner 315 of the A-type separator 31 is configured in the same way as the upper left corner 316 of the B-type separator 32. This configuration increases the rigidity around the corner recesses 505, 506 of the separator 3, preventing damage to the corners 315, 316 around the corner recesses 505, 506 during transport or stacking of the thin plate-shaped separator 3.

[0081] (2) The corner recess 506 has a pair of opposing side surfaces 506a, 506a (Figure 6B). The rib 35 (outer rib 360) is provided continuously from the pair of side surfaces 506a, 506a to a pair of chamfered portions 520, 520 and the upper edge 311 or left edge 314 (Figure 6B). By providing the rib 35 continuously in this way, the strength of the corners 315, 316 of the separator 3 is improved and bending of the protruding portion 52 can be prevented. The guide member 51 is engaged with the corner recess 506, but by providing the rib 35 on the edge of the corner recess 506, damage to the corner recess 506 when the separators 3 are stacked can also be prevented.

[0082] (3) The corner recess 506 is configured such that the center P1 of the guide member 51 is located closer to the center of the separator 3 than the chamfered portion 520 (Figure 6B). This allows the guide member 51 to properly position the separator 3 when stacking the separators 3.

[0083] (4) The outer edge portion 34 of the type B separator 32 has an upper outer edge portion 34U of the first range AR1 and a left outer edge portion 34L of the third range AR3 that are connected to a pair of chamfered portions 520, 520 and extend along a pair of sides (upper side 311, left side 314), and an upper outer edge portion 34U of the second range AR2 and a left outer edge portion 34L of the fourth range AR4 that are connected to these upper outer edge portions 34U and left outer edge portions 34L and extend substantially parallel to a pair of sides (upper side 311, left side 314) (Figure 6B). The upper outer edge portion 34U of the second range AR2 and the left outer edge portion 34L of the fourth range AR4 are recessed compared to the upper outer edge portion 34U of the first range AR1 and the left outer edge portion 34L of the third range AR3 (Figure 6B). This increases the overall strength of the corners 315 and 316, and effectively prevents damage to the corners 315 and 316.

[0084] (5) The separator 3 has A-type separators 31 and B-type separators 32 stacked alternately via UA2 (Figure 1). The B-type separator 32 has a corner recess 506 at the upper left corner 316 where the upper edge 311 and the left edge 314 intersect, and the A-type separator 31 has a notch 515 at the upper left corner 316 that is cut out on the central side of the separator 3 from the corner recess 506 (Figures 6A, 6B). As a result, at the positioning part of the separator 3 that engages with the guide member 51, the notch 515 of the A-type separator 31 is retracted from the corner recess 506 of the B-type separator 32, so that a sufficient insulation distance can be secured between the separators 3, 3 at the positioning part.

[0085] (6) The B-type separator 32 has protrusions 391 and 393 of the first range AR1 and the third range AR3, and recesses 382 and 384 of the second range AR2 and the fourth range AR4 (Figure 6B). The A-type separator 31 has an upper outer edge 34U of the first range AR1 and a left outer edge 34L of the third range AR3, which are connected to the notch 515 and extend along the upper edge 311 and the left edge 314, and have the same length as the protrusions 391 and 393, and an upper outer edge 34U of the second range AR2 and a left outer edge 34L of the fourth range AR4, which are connected to these upper outer edge 34U and left outer edge 34L and extend substantially parallel to the upper edge 311 and the left edge 314, and have the same length as the recesses 382 and 384 (Figure 6A). The upper outer edge 34U of the first range AR1 and the left outer edge 34L of the third range AR3 of the A-type separator 31 are recesses 381 and 383 that are recessed more than the protrusions 391 and 393 of the B-type separator 32, and the upper outer edge 34U of the second range AR2 and the left outer edge 34L of the fourth range AR4 of the A-type separator 31 are protrusions 392 and 394 that protrude more than the recesses 382 and 384 of the B-type separator 32 (Figure 6A). This ensures a sufficient insulation distance along the outer edge 33 of the separator 3.

[0086] The above embodiment can be modified into various forms. Several modifications are described below. In the above embodiment, a guide member 51 with a substantially circular cross-section extends in a predetermined direction along the outer edge 33 (edge) of the cell laminate 10 (laminated body), but the cross-sectional shape of the positioning member is not limited to that described above. Therefore, the configuration of the corner recesses 505, 506 as engaging recesses that engage with the positioning member, and the configuration of the pair of protrusions 52 formed on both sides of the corner recesses 505, 506 are not limited to those described above. That is, the configuration of the corner where a pair of sides of the separator 3 intersect can be anything as long as it has an engaging recess recessed toward the center of the separator 3 so as to engage with the positioning member, and a pair of protrusions formed on both sides of the engaging recess, and the configuration of the pair of protrusions can be anything as long as it has a chamfered tip and a rib extending along each edge of the pair of protrusions via the chamfered tip.

[0087] In the above embodiment, a rib 35 (rib portion) having an inner rib 350, an outer rib 360, and an intermediate rib 370 is provided on the outer edge 34 near the corners 315, 316 of the separator 3. However, the inner rib 350 and the intermediate rib 370 can be omitted, and the configuration of the rib portion is not limited to that described above. In the above embodiment, the separator 3 is composed of an A-type separator 31 (second separator) and a B-type separator 32 (first separator), and the outer edge portions 34 (first edge portion) of the first range AR1 and third range AR3 of the B-type separator 32 are configured to be more concave than the outer edge portions 34 (second edge portion) of the second range AR2 and fourth range AR4. That is, the first edge portion is configured as a convex portion 391, 393 and the second edge portion as a concave portion 382, ​​384, but the configuration of the first separator is not limited to that described above. In the above embodiment, the outer edges 34 (third edge) of the first range AR1 and the third range AR3 of the A-type separator 31 are made to protrude more than the outer edges 34 (fourth edge) of the second range AR2 and the fourth range AR4. That is, the third edge is configured as a recess 381, 383 and the fourth edge as a convex portion 392, 394, but the configuration of the second separator is not limited to the above.

[0088] In the above embodiment, an example of applying the fuel cell stack 100 to a vehicle was described, but the fuel cell stack of the present invention can also be applied to mobile bodies other than vehicles such as aircraft and ships, robots, and various industrial machines.

[0089] The above description is merely an example, and the present invention is not limited by the embodiments and modifications described above, as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiments and modifications, and to combine modifications with each other.

[0090] 1 Power generation cell, 2 Integrated electrode assembly, 3 Separator, 10 Cell stack, 31 Type A separator, 32 Type B separator, 33 Outer edge, 34 Outer edge portion, 35 Rib, 51 Guide member, 52 Protruding portion, 100 Fuel cell stack, 311 Top edge, 314 Left edge, 315 Upper left corner, 316 Lower right corner, 360 Outer rib, 505, 506 Corner recess, 506a Side surface, 515, 516 Notch portion, 520 Chamfered portion, 381-384 Recess, 391-394 Protrusion

Claims

1. A fuel cell stack comprising: a laminate formed by alternately stacking a membrane electrode structure including an electrolyte membrane and an electrode, and a separator in a predetermined direction; and a positioning member extending in the predetermined direction along the edge of the laminate, wherein the edge of the separator has an engaging recess formed toward the center of the separator at the corner where a pair of sides of the separator intersect, so as to engage with the positioning member, and a pair of protrusions formed on both sides of the engaging recess, and each of the pair of protrusions has a chamfered tip and a rib extending along the edge of each of the pair of protrusions via the chamfered tip.

2. A fuel cell stack according to claim 1, wherein the engaging recess has a pair of sides facing each other, and the rib portion is provided continuously from the pair of sides to the pair of chamfered portions and the pair of edges.

3. A fuel cell stack according to claim 1, characterized in that the engaging recess is configured such that the center of the positioning member is located on the central side of the separator than the chamfered portion.

4. A fuel cell stack according to any one of claims 1 to 3, wherein the edge of the separator has a pair of first edge portions connected to a pair of chamfered portions and extending along the pair of sides, and a pair of second edge portions connected to the pair of first edge portions and extending substantially parallel to the pair of sides, wherein the pair of second edge portions are recessed compared to the pair of first edge portions.

5. A fuel cell stack according to claim 4, wherein the separator comprises a first separator and a second separator alternately stacked via the membrane electrode structure, the first separator has the engagement recess at the corner where the pair of sides intersect, and the second separator has a notch at the corner where the pair of sides intersect that is cut out on the central side of the separator than the engagement recess.

6. A fuel cell stack according to claim 5, wherein the first separator further comprises the pair of first edges and the pair of second edges, the second separator comprises the pair of third edges having the same length as the pair of first edges and extending along the pair of sides connected to the notch, and the pair of fourth edges having the same length as the pair of second edges and extending substantially parallel to the pair of sides connected to the pair of third edges, the pair of third edges being recessed compared to the pair of first edges, and the pair of fourth edges protruding compared to the pair of second edges.

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