Fuel cell stack

Abstract

Fuel cell stack (100; 100a; 100b; 100c), comprising: a stack (20) having a plurality of stacked unit cells (10); a housing (40) which receives the stack (20); and an end plate (30; 30a; 30b; 30c) which is arranged outside the plurality of unit cells (10) with respect to the stack (20) in the stacking direction and in which fluid flow path holes (70) penetrating them in the stacking direction and a receiving groove (80) receiving a sealing element (SL) for sealing a part between the receiving groove (80) and the housing (40) are formed, wherein the end plate (30; 30a; 30b; 30c) covers an end face of the stack in the stacking direction and an end face of the housing (40) in the stacking direction and is fixed to the end face of the housing (40), the end plate (30; 30a; 30b; 30c) has: a metal member (31; 31a; 31b; 31c) formed with the fluid flow path holes (70), a first recess (81) and a second recess (82) continuous to the first recess (81), and a resin layer (90) continuously covering an inner peripheral wall surface of the fluid flow path holes (70), a surface facing the stack (20), a part including at least one outer peripheral end at the first recess (81), and the second recess (82) in the metal member, wherein the resin layer (90) is formed with the receiving groove (80) at a surface corresponding to the end face of the housing (40) at a part covering the part including at least the outer peripheral end at the first recess (81), the second recess (82) receives a part of the resin layer (90) to restrict the resin layer (90), the second recess (82) has a third recess (83) along the stacking direction at the outer peripheral end of the first recess (81), which is arranged along the stacking direction and is continuous to a part on an opposite side to the receiving groove (80), at least a part of the third recess (83) is formed along the stacking direction in such a way that it corresponds to a conical shape whose cross-sectional area gradually increases perpendicular to the stacking direction, starting from the stack along the stacking direction towards the end plate (30; 30a; 30b; 30c), and the entirety of the third recess (83) along the stacking direction is formed such that it corresponds to the conical shape.

Description

Background area

[0001] The present disclosure relates to a fuel cell stack. Related state of the art

[0002] Inside a fuel cell stack having a configuration in which both ends in a stacking direction of a stack of a plurality of unit cells are held between a pair of terminals and a pair of end plates, a plurality of manifolds for supplying reaction gas to the unit cells, discharging exhaust gas from the unit cells, and supplying and discharging a cooling medium to the unit cells are formed parallel to the stacking direction. At least one of the end plates is formed with a plurality of through holes for connection to the manifolds in the fuel cell stack. Generally, the end plates are made of metal such as an aluminum alloy. Therefore, a technology for covering a contact surface between the end plates and the terminals has been developed.inner peripheral walls of the through-holes formed in the end plates by a resin layer to prevent the insulation property and the corrosion protection property from decreasing due to the reaction gas, the cooling medium or the like (see JP 2015 - 8 086 A).

[0003] The fuel cell stack may have a configuration for accommodating the stack of unit cells in a casing. In this case, one end surface of the entire casing and one end surface of the stack accommodated in the casing are covered with the end plates, and a periphery of an outer edge of the casing and the end plates are fastened by a bolt or the like. At this time, a sealing member such as a gasket is interposed between contact surfaces of the end plates and the casing to ensure airtightness and watertightness of the contact surfaces of the end plates and the casing. The sealing member is accommodated, for example, in a receiving groove provided in the end plates.

[0004] However, there is a problem that a gap is created between the resin layer and a metal member constituting the end plates, the reaction gas and the cooling medium enter the gap, and the insulation property and the corrosion protection property deteriorate. For example, the gap may be created by repeatedly applying stress to the resin layer due to a difference in thermal expansion coefficients between the resin layer and the metal member, which is caused by repeated operation and stop of a fuel cell. For example, in another case, when the resin layer forms a configuration to cover an inner surface of the receiving groove by resin molding, the gap may be created by separation of the resin layer from the receiving groove of the metal member upon shrinkage of the resin layer.Therefore, a technology capable of preventing the resin layer from peeling off the metal element at the end plates is desirable.

[0005] Furthermore, DE 10 2015 117 654 A1 discloses a vehicle comprising a fuel cell having a cell stack and an end plate that absorbs a pressing force, the end plate being of such strength that it can withstand the pressing force; and a vehicle-side stacking frame to which the fuel cell is mounted in an underbody region of the vehicle in a mounting position such that the fuel cell unit cells are stacked horizontally. The vehicle-side stacking frame extends over a range from one side of the end plate to the other end side of the cell stack in the stacking direction of the fuel cell unit cells in an installation range that the fuel cell occupies in the mounting position in the underbody region of the vehicle.In an area where an external force is assumed to be able to reach the installation area near the end plate, the vehicle-side stacking frame has a shortest distance to the end plate that is less than a shortest distance to any other components near the end plate.

[0006] EP 2 608 300 A1 discloses an end plate assembly for a fuel cell stack, comprising: a support structure for mechanical load transmission, and at least one insulating structure which at least partially covers a front side of the support structure and faces at least one fuel cell, wherein the insulating structure and the support structure are inseparably connected to one another.

[0007] Furthermore, JP 2006-147511 A discloses a fuel cell stack provided with an end plate on which fluid communication holes are arranged. A resin molded part is attached to the end plate corresponding to the inner peripheral surfaces of the respective fluid communication holes. In this resin molded part, annular groove portions are formed around the fluid communication holes, and O-rings are arranged and installed on the annular groove portions. Summary

[0008] The above problems and the resulting task are solved by the subject matter of the independent claims 1 to 3.

[0009] According to an illustrative aspect of the present disclosure, a fuel cell stack is provided. The fuel cell stack includes: a stack having a plurality of stacked unit cells; a casing that accommodates the stack; and an end plate that is arranged outside the plurality of unit cells with respect to the stack in the stacking direction, and in which fluid flow path holes penetrating them in the stacking direction and a receiving groove that accommodates a sealing member for sealing a portion between the receiving groove and the casing are formed. The end plates cover one end surface of the stack in the stacking direction and one end surface of the casing in the stacking direction, and are fixed to the end surface of the casing.The end plates include a metal member formed with fluid flow path holes, a first recess, and a second recess continuous with the first recess, and a resin layer continuously covering inner peripheral wall surfaces of the fluid flow path holes, a stack-facing surface, a portion including at least one outer peripheral end in the first recess, and the second recess in the metal member. The resin layer is formed with the receiving groove on a surface corresponding to the end face of the housing at a portion including the portion including at least the outer peripheral end in the first recess. The second recess receives a portion of the resin layer to restrict the resin layer or restrict the movement of the resin layer.

[0010] According to the fuel cell stack of this aspect, in the end plate, the second recess, which confines the resin layer by accommodating a portion of the resin layer covering the inner peripheral wall surfaces of the fluid flow path holes, the surface where the end plates and the stack face each other, the portion including at least one outer peripheral end at the first recess, and the second recess at the metal member, is continuous to the first recess. Therefore, in the end plate, when stress due to a difference in thermal expansion coefficients between the resin layer and the metal member is repeatedly applied to the resin layer and the resin layer attempts to contract during resin molding, the resin layer can be prevented from peeling off from the metal member.

[0011] In the fuel cell stack of the aspect, the second recess along the stacking direction has, at the outer peripheral end of the first recess, a third recess arranged along the stacking direction and continuous to a portion on an opposite side to the receiving groove. At least a portion of the third recess along the stacking direction may be formed to correspond to a conical shape whose cross-sectional area gradually increases perpendicular to the stacking direction from the stack along the stacking direction toward the end plate.

[0012] In the fuel cell stack of the above-described aspect, the entirety of the third recess along the stacking direction may be formed in the conical shape.

[0013] In the fuel cell stack of the above-described aspect, the second recess along the stacking direction has, at the inner peripheral end of the first recess, a fourth recess arranged along the stacking direction and continuous to a portion on an opposite side to the receiving groove. At least a portion of the fourth recess along the stacking direction may be formed to have a tapered shape whose cross-sectional area gradually increases perpendicular to the stacking direction from the stack toward the end plate.

[0014] In the fuel cell stack of the above-described aspect, the entirety of the fourth recess along the stacking direction may be formed in the conical shape.

[0015] In the fuel cell stack of the above-described aspect, the second recess has a third recess and a fourth recess. The third recess is arranged along the stacking direction and is continuous along the stacking direction from the outer peripheral end of the first recess to a part on an opposite side to the receiving groove. The entirety of the third recess along the stacking direction is formed to conform to a conical shape whose cross-sectional area perpendicular to the stacking direction gradually increases from the stack along the stacking direction toward the end plates. The fourth recess is arranged along the stacking direction and is continuous along the stacking direction from the inner peripheral end of the first recess to a part on the opposite side to the receiving groove.The entirety of the fourth recess along the stacking direction is formed in the conical shape.

[0016] The present invention may be embodied in various embodiments and aspects. For example, the present disclosure may be embodied in an embodiment such as a fuel cell system having a fuel cell stack and a vehicle having the fuel cell system. Short description of the figures Fig. 1 is a cross-sectional view showing a schematic configuration of a fuel cell stack according to an embodiment of the present invention; Fig. 2 is an enlarged cross-sectional view showing a configuration of a first end plate; Fig. 3 is an enlarged cross-sectional view showing a Fig. 2 shows the area shown; Fig. 4 is an enlarged cross-sectional view showing a configuration of a first end plate in a fuel cell stack as a second embodiment; Fig. 5 is an enlarged perspective view showing the configuration of the Fig. 4 further shows the first end plate 30a shown; Fig. 6 is an explanatory diagram showing an example of an aluminum mold; Fig. 7 is an explanatory diagram showing an example of a resin molding die; Fig. 8 is an enlarged cross-sectional view showing a configuration of a first end plate in a fuel cell stack as a third embodiment; and Fig. 9 is an enlarged cross-sectional view showing a configuration of a first end plate in a fuel cell stack as a fourth embodiment. Description of Embodiments A. First Embodiment A1. Configuration of the Fuel Cell Stack

[0017] Fig. 1 is a cross-sectional view showing a schematic configuration of a fuel cell stack in an embodiment of the present invention. Fig. 1 shows a cross section along a stacking direction of a fuel cell stack 100. In Fig. 1, a Z-axis is set parallel to a vertical direction, and an X-axis and a Y-axis are set parallel to a horizontal direction, respectively. A +Z direction corresponds to a vertically upward direction, and a -Z direction corresponds to a vertically downward direction. The stacking direction is parallel to the X-axis. The X-axis, Y-axis, and Z-axis in Fig. 1 correspond to the X-axis, Y-axis and Z-axis in the other figures.

[0018] The fuel cell stack 100 includes a stack 20, a first end plate 30, a second end plate 35, a casing 40, and a plurality of bolts 50. The stack 20 is configured to include a plurality of unit cells 10 stacked along the stacking direction. Specifically, the stack 20 includes the plurality of unit cells 10, a pair of terminal plates (not shown), and a pair of insulators (not shown). Each of the unit cells 10 corresponds to a solid polymer fuel cell and generates electric power through an electrochemical reaction using a reaction gas supplied to an anode-side catalyst electrode layer and a cathode-side catalyst electrode layer, which are provided with a solid polymer electrolyte membrane therebetween.On the outer side of each of the catalyst electrode layers of the electrodes in the unit cells 10, for example, a gas diffusion layer formed of a porous carbon body, such as carbon paper, and carbon cloth, is arranged. A separator with a conductive property is arranged on the outer side of each of the gas diffusion layers of the electrodes. Within the fuel cell stack 100, a plurality of manifolds for supplying the reaction gas to the unit cells 10, for discharging exhaust gas from the unit cells 10, and for supplying and discharging a cooling medium to and from the unit cells 10 are formed parallel to the stacking direction.

[0019] The first end plate 30 is arranged on the outer side (-X direction) in the stacking direction with respect to one end face (-X direction end face) of the two end faces in the stacking direction of the stack 20. Specifically, a terminal plate (not shown) is arranged in contact with the end face on the -X direction side of the unit cell 10, that is, one end in the -X direction. The first end plate 30 is arranged on the outer side (-X direction) in the stacking direction, with an insulator (not shown) interposed between it and the terminal plate.

[0020] The first end plate 30 includes a plate-shaped metal member (metal member 31, described later) and a resin layer (resin layer 90, described later). The shape of the first end plate 30 in a plan view (a shape viewed in the +X direction) is substantially rectangular. The area of the shape is larger than the area of the end surface along the stacking direction of the stack 20 in a plan view. The first end plate 30 accommodates the stack 20 with a second end plate (second end plate 35, described later) with a predetermined pressure therebetween. The first end plate 30 and a housing (housing 40, described later) are fixed by the bolts 50 to maintain the stacked state of the stack 20. The first end plate 30 is formed with a plurality of through holes penetrating it in a thickness direction (X-axis direction).The plurality of through holes serve as fluid flow path holes that communicate with the plurality of manifolds formed inside the stack 20. Specifically, the through holes serve as supply flow path holes for the reaction gas and the cooling medium to the stack 20 and as discharge flow path holes for the exhaust gas and the cooling medium from the stack 20. The first end plate 30 is formed with a plurality of recesses (first recess 81 and second recess 82, described later) in the +X direction of the first end plate 30.

[0021] The second end plate 35 is arranged on the opposite side (+X direction) in the stacking direction of the stack 20 to the side on which the first end plate 30 is arranged, on the outer side (+X direction) in the stacking direction, with respect to the end surface of the two end surfaces. In the same manner as the above-described first end plate 30, a terminal plate is arranged in contact with the end surface in the +X direction of the unit cell 10, that is, one end in the +X direction. The second end plate 35 is arranged on the outer side (+X direction) in the stacking direction, with an insulator interposed between it and the terminal plate. The second end plate 35 has a plate-like appearance similar to the first end plate 30 and is formed of a metal member, which in the present embodiment is formed of an aluminum alloy.The second end plate 35 is smaller than the first end plate 30 when viewed in the direction of the X-axis.

[0022] The casing 40 has an appearance of a bottomed cylindrical shape in which an opening is formed at one end in the -X direction and the end on the opposite side (+X direction side) is closed. The stack 20 and the second end plate 35 are housed inside the casing 40. As shown in the figure, the first end plate 30 is arranged such that the +X direction end surface of the first end plate 30 covers the -X direction end surface of the stack 20 and the -X direction end surface of the casing 40, and is fixed by the bolts 50 to the periphery of the outer edge of the casing 40. The casing 40 is excellent in waterproof performance, dust resistance, and shock resistance and, in the present embodiment, is formed of an aluminum alloy. A2. Detailed configuration of the first end plate 30

[0023] Fig. 2 is an enlarged cross-sectional view showing the configuration of the first end plate 30. Fig. 3 is an enlarged cross-sectional view showing a Fig. 2. The area Ar1 corresponds to an area encompassing the end of the first end plate 30 in the +Z direction. Fig. 2 is enlarged and shows the configuration of the X-direction end face of the Fig. 1 shown fuel cell stack 100. As in Fig. 2, the first end plate 30 includes a metal member 31 and a resin layer 90.

[0024] The metal member 31 is formed from a metallic plate-shaped member. In the present embodiment, the metal member 31 is formed from an aluminum alloy. Instead of the aluminum alloy, the metal member 31 may be formed from any metal, such as a titanium alloy and stainless steel. The metal member 31 is formed with fluid flow path holes 70, a first recess 81, and a second recess 82.

[0025] As in Fig. 2, the fluid flow path holes 70 correspond to through holes formed along the thickness direction (X-axis direction) of the first end plate 30. As described above, the fluid flow path holes 70 communicate with manifolds 21 formed in the stack 20, and these are used as flow paths of the cooling medium. In a cross section of the first end plate 30 at a different position from that in Fig. 2, instead of the distributors 21, supply flow paths of the reaction gas or the discharge flow paths of the exhaust gas appear.

[0026] As in Fig. 2 and Fig. As shown in Fig. 3, the first recess 81 and the second recess 82 accommodate a part of the resin layer 90. The first recess 81 is formed in a ring shape at the periphery of an outer edge of the housing 40 at a surface of the first end plate 30 of the two facing surfaces of the first end plate 30 and the housing 40 when the surface in the +X direction of the first end plate 30 and the surface in the -X direction of the housing 40 are fixed. The first recess 81 corresponds to a recess that opens toward the housing 40 (in other words, opens in the +X direction), and has the -X direction as a depth direction.

[0027] The second recess 82 is at an outer peripheral surface (outer peripheral surface of the +Z direction in Fig. 3) of the first recess 81 continuous or continuous to the first recess 81. The second recess 82 opens towards an inner peripheral side (-Z direction in Fig. 3) the first recess 81, and this has an outer circumferential direction of the first recess 81 as a depth direction. Inner surfaces of the first recess 81 and the second recess 82 are covered by the resin layer 90. The second recess 82 accommodates a portion of the resin layer 90 to restrict the resin layer 90. In the present embodiment, "restrict" means preventing movement.

[0028] The resin layer 90 is formed on a surface of the metal member 31 near the fluid flow path holes 70, and is used to prevent the cooling medium from leaking from the fluid flow path holes 70. The resin layer 90 is used to prevent the insulation property and anti-corrosion property from deteriorating due to the cooling medium. The resin layer 90 is formed with a receiving groove 80.

[0029] The receiving groove 80 corresponds to a groove for receiving a sealing element SL. The receiving groove 80 is formed on a surface corresponding to an end face in the -X direction of the housing 40 at a part covering the first recess 81 in the resin layer 90.

[0030] The sealing element SL received in the receiving groove 80 is used to seal contact surfaces of the first end plate 30 and the casing 40. The sealing element SL absorbs a fastening load when fastening the fuel cell stack 100 and seals a portion between the first end plate 30 and the casing 40 through a surface pressure of the sealing element SL. This ensures the airtightness and watertightness of the fuel cell stack 100. In the present embodiment, the sealing element SL is formed of a rubber. For example, butyl rubber or silicone rubber can be used as the rubber.

[0031] The resin layer 90 is formed such that it continuously covers four regions described below. That is, the resin layer 90 is firstly formed such that it covers the inner peripheral wall surfaces of the fluid flow path holes 70 in the metal member 31. The resin layer 90 is secondly formed such that it covers a surface in the metal member 31 that faces a surface of the stack 20 in the -X direction. The resin layer 90 is thirdly formed such that it has a part (one end in the +Z direction in Fig. 3) including at least one outer peripheral end of the first recess in the metal member 31. Fourth, the resin layer 90 is formed to cover the second recess in the metal member 31. The resin layer 90 is also formed between these four regions. In other words, the resin layer 90 is formed to continuously cover the inner peripheral wall surfaces of the fluid flow path holes 70, the surface facing the stack 20, the part including at least the outer peripheral end of the first recess, and the second recess in the metal member 31.

[0032] In the present embodiment, the resin layer 90 is formed of an insulating polymer material, for example, a polyolefin such as polypropylene (PP) or an engineering plastic such as polyamide (PA) and polyphenylene sulfide (PPS). Suitable materials include aromatic polyamide or polyphenylene sulfide (PPS).

[0033] The resin layer 90 can be formed by placing a die having a shape of the resin layer 90 on the metal member 31 formed with the fluid flow path holes 70, the first recess 81, the second recess 82, and the like, and injection-molding it with a resin material. When the resin layer 90 is formed, mold shrinkage of the resin may occur. However, a portion of the resin layer 90 penetrates into the second recess 82, and thereby the resin layer 90 can be prevented from moving at least in the +X direction. Similarly, the resin layer 90 can be prevented from moving at least in the +X direction even if stress due to a difference in thermal expansion coefficients between the resin layer 90 and the metal member 31 is repeatedly applied to the resin layer 90 while the fuel cell stack 100 is actually used.

[0034] According to the fuel cell stack 100 of the above-described first embodiment, the first end plate 30 is formed with the second recess 82 that confines the resin layer 90 by accommodating a part of the resin layer 90 that continuously covers the inner peripheral wall surfaces of the fluid flow path holes 70, the surface where the first end plate 30 and the stack 20 face each other, the part including at least the outer peripheral end of the first recess 81, and the second recess 82 at the metal member 31, and is continuous with the first recess 81 formed at the outer peripheral surface of the accommodating groove 80.Therefore, the resin layer 90 can be prevented from peeling off from the metal member 31 when a stress due to a difference in thermal expansion coefficients between the resin layer 90 and the metal member 31 is repeatedly applied to the resin layer 90, or when the resin layer 90 tries to contract during resin molding. B. Second embodiment

[0035] Fig. 4 is an enlarged cross-sectional view showing a configuration of a first end plate 30a in a fuel cell stack 100a as a second embodiment. Fig. 5 is an enlarged perspective view showing the configuration of the Fig. 4 shows the first end plate 30a. Fig. 4 and Fig. 5 and show the area including the end of the first end plate 30a in the +Z direction similar to Fig. 3. Although not shown, the configuration of the first end plate 30a on the -Z direction side is similar to the configuration of the first end plate 30a shown in Fig. 4 and Fig. 5 shown side of the +Z direction. In Fig. 5, some components (the fourth recess 84 described later, etc.) of the first end plate 30a are omitted for convenience of description. The fuel cell stack 100a of the second embodiment differs from the fuel cell stack 100 of the first embodiment in that it includes the first end plate 30a instead of the first end plate 30 and includes a metal member 31a instead of the metal member 31. Other configurations in the fuel cell stack 100a of the second embodiment are the same as those in the fuel cell stack 100 of the first embodiment. Therefore, the same reference numeral is assigned to the same component, and the detailed description thereof is omitted.

[0036] The first end plate 30a of the second embodiment differs from the first end plate 30 of the first embodiment in that the metal member 31a includes a plurality of third recesses 83 and a plurality of fourth recesses 84. In the second embodiment, the third recess 83 and the fourth recess 84 correspond to the second recess in the disclosure.

[0037] As in Fig. 4, the third recess 83 is formed such that it is substantially parallel to the X-axis from the outer peripheral surface of the end of the first recess 81 in the +Z direction and the -X direction to the end surface of the metal element 31a on the -X direction side. The fourth recess 84 is formed such that it is substantially parallel to the X-axis from the outer peripheral surface of the end of the first recess 81 in the -Z direction and the -X direction to the end surface of the metal element 31a on the -X direction side. As shown in Fig. 5, the plurality of third recesses 83 are formed adjacent to each other at predetermined intervals along the Y-axis. Fig. 5, the plurality of fourth recesses 84 are not shown. However, the plurality of fourth recesses 84 are formed in a similar manner to the plurality of third recesses 83, adjacent to each other at predetermined intervals along the Y-axis. The shapes of the third recess 83 and the fourth recess 84 in a plan view (configurations viewed in the +X direction) correspond to circles. As shown in Fig. As shown in FIG. 4, the third recess 83 and the fourth recess 84 are formed as conical shapes whose cross-sectional areas increase in the -X direction parallel to the YZ plane surface. Therefore, even if the resin attempts to contract after the resin penetrates into the third recess 83 and the fourth recess 84 during molding of the resin layer 90, the resin (resin layer 90) is prevented from moving at least in the +X direction. Even if stress is repeatedly applied to the resin layer 90 due to a difference in thermal expansion coefficients between the resin layer 90 and the metal member 31 while the fuel cell stack 100a is actually used, after the resin layer 90 is formed, a part of the resin layer 90 enters the third recess 83 and the fourth recess 84, and thereby the resin layer 90 can be prevented from moving at least in the +X direction.The first end plate 30a having such a configuration is manufactured by molding a metal (aluminum) and a resin using a die.

[0038] Fig. 6 is an explanatory diagram showing an example of an aluminum forming die 300. The aluminum forming die 300 is used to form a base material (hereinafter referred to as an "aluminum half-mold") of the metal member 31a of the first end plate 30a. Fig. 6 is enlarged and shows a part corresponding to a part near the first recess 81, the third recess 83 and the fourth recess 84 in the first end plate 30a. As in Fig. As shown in FIG. 6, the aluminum forming tool 300 includes a lower die 301 and an upper die 302. The lower die 301 includes protrusions 311, 312. The protrusions 311, 312 are formed in shapes corresponding to the shapes of the third recess 83 and the fourth recess 84, that is, tapered shapes whose cross-sectional areas increase in the -X direction parallel to a YZ plane surface. The upper die 302 includes a protrusion 320. The protrusion 320 has a shape corresponding to the shape of the first recess 81 and is formed to be one size larger than that of the first recess 81.

[0039] The aluminum half-mold (aluminum half-mold al1, as described later) is formed in a process described later. As in Fig. As shown in Fig. 6, the end surface of the protrusions 311, 312 in the +X direction of the lower die 301 and the end surface of the protrusion 320 in the -X direction of the upper die 302 are arranged to face and contact each other, and they are clamped with a predetermined clamping pressure. At this time, air gaps c1, c2, and c3 are formed in the aluminum die 300. Aluminum is introduced into the air gaps c1, c2, and c3. Then, after the aluminum is cooled for a predetermined time, an aluminum half-mold (aluminum half-mold a1 described later) whose shape is substantially the same as that of the air gaps c1, c2, and c3 is obtained.

[0040] Fig. Fig. 7 is an explanatory diagram showing an example of a resin mold 400. In a similar manner to Fig. 6 enlarged and shows Fig. 7 parts according to components near the first recess 81, the third recess 83, and the fourth recess 84 in the first end plate 30a. The resin mold 400 is used in molding the resin layer 90 in contact with the above-described aluminum half-mold. Fig. 7 shows a state in which the resin mold 400 is arranged with respect to the aluminum half-mold a1. The resin mold 400 includes a lower die 401 and an upper die 402.

[0041] The lower die 401 is arranged in contact with the end face of the aluminum half-mold al1 in the -X direction, while the upper die 402 is arranged in contact with the end face of the aluminum half-mold al1 in the +X direction. The upper die 402 includes the protrusion 420. The protrusion 420 has a shape corresponding to that of the first recess 81 and is formed to have a size substantially equal to that of the first recess 81. In a state where the upper die 402 is arranged at a planned position, the protrusion 420 does not contact the aluminum half-mold al1, and a gap is formed between the protrusion 420 and the aluminum half-mold al1.

[0042] The resin layer 90 is formed in the process described below. As shown in Fig. As shown in Fig. 7, the end face of the aluminum half-mold al1 in the -X direction and the end face of the lower die 401 in the +X direction are arranged to face each other and contact each other. The end face of the aluminum half-mold al1 in the +X direction and the end face of the upper die 402 in the -X direction are arranged to face each other and contact each other. At this time, in the resin mold 400, a surface is formed in which the end face of the aluminum half-mold al1 in the +X direction and the end face of the projection 420 in the -X direction face each other, and an air gap c4 is formed at parts corresponding to the projections 311, 312 of the lower die 301 of the aluminum mold 300. The shape of the air gap c4 is essentially the same as that of the resin layer 90.A resin element is introduced into the air gap c4 and the resin layer 90 is formed.

[0043] The fuel cell stack 100a of the second embodiment having the above-described configuration has a similar effect to that of the fuel cell stack 100 of the first embodiment. That is, when stress due to a difference in thermal expansion coefficients between the resin layer 90 and the metal member 31 is repeatedly applied to the resin layer 90, and when the resin layer 90 attempts to contract during resin molding, the resin layer 90 can be prevented from moving at least in the +X direction, and the resin layer 90 can be prevented from peeling off the metal member 31a. Since there is no need to perform separation when the first recess 81, the third recess 83, and the fourth recess 84 are formed, the manufacturing cost can be reduced.Since a part of the first recess 81 can be prevented from being accidentally separated during separation, the sealing property by the sealing element SL can be prevented from decreasing. C. Third embodiment

[0044] Fig. Fig. 8 is an enlarged cross-sectional view showing a configuration of a first end plate 30b in a fuel cell stack 100b as a third embodiment. In a similar manner to Fig. 4 enlarged and shows Fig. 8 shows a region including an end of the +Z direction at the first end plate 30b. Although not shown, a configuration of the first end plate 30b on the -Z direction side is the same as the configuration of the Fig. 8 in the +Z direction. The fuel cell stack 100b of the third embodiment differs from the fuel cell stack 100a of the second embodiment in that it includes the first end plate 30b instead of the first end plate 30a and includes the metal member 31b instead of the metal member 31a. Other configurations in the fuel cell stack 100b of the third embodiment are the same as those of the fuel cell stack 100a of the second embodiment. Therefore, the same reference numeral is assigned to the same component, and the detailed description thereof is omitted.

[0045] The first end plate 30b of the third embodiment differs from the first end plate 30a of the second embodiment in that the plurality of fourth recesses 84 are omitted from the metal member 31b. In the third embodiment, the third recess 83 corresponds to the second recess in the disclosure.

[0046] The fuel cell stack 100b of the third embodiment having the above configuration has a similar effect to the fuel cell stack 100a of the second embodiment. Since there is no need to form the plurality of fourth recesses 84 in the metal member 31b, the manufacturing cost can be reduced. D. Fourth embodiment

[0047] Fig. Fig. 9 is an enlarged cross-sectional view showing a configuration of a first end plate 30c in a fuel cell stack 100c as a fourth embodiment. In a similar manner to Fig. 4 enlarged and shows Fig. 9 shows a region including one end of the first end plate 30c in the +Z direction. Although not shown, a configuration of the side of the first end plate 30c in the -Z direction is the same as the configuration of the Fig.9 in the +Z direction. The fuel cell stack 100c of the fourth embodiment differs from the fuel cell stack 100a of the second embodiment in that it includes the first end plate 30c instead of the first end plate 30a and includes a metal member 31c instead of the metal member 31a. Other configurations in the fuel cell stack 100c of the fourth embodiment are the same as those of the fuel cell stack 100a of the second embodiment. Therefore, the same reference numeral is assigned to the same component, and the detailed description thereof is omitted.

[0048] The first end plate 30c of the fourth embodiment differs from the first end plate 30a of the second embodiment in that the plurality of third recesses 83 in the metal member 31c are omitted. In the fourth embodiment, the fourth recess 84 corresponds to the second recess in the means for solving the problem.

[0049] The fuel cell stack 100c of the fourth embodiment having the above configuration has a similar effect to the fuel cell stack 100a of the second embodiment. Since there is no need to form the plurality of third recesses 83 in the metal member 31c, the manufacturing cost can be reduced. E. Modification:E1. Modification 1:

[0050] In the above-described embodiments, the fluid flow path holes 70, whose inner peripheral wall surfaces are covered by the resin layer 90, correspond to flow paths of the cooling medium. Instead of the flow paths or in addition to the flow paths, the inner peripheral wall surfaces of the flow paths of the reaction gas and the exhaust gas may be covered by the resin layer 90. With such a configuration, an effect similar to that of the above-described embodiments is achieved. E2. Modification 2:

[0051] In Embodiments 2 to 4 described above, the third recess 83 and the fourth recess 84 are continuous with the first recess 81. However, the third recess 83, the fourth recess 84, and the first recess 81 may be configured to be connected via a column (hereinafter referred to as a "column part") with the X-axis direction as the axis direction. In this case, the lengths in the Z direction of the end in the +X direction of the third recess 83 and the fourth recess 84 are set larger than the length in the Z direction of the end in the -X direction at the column part to form steps between the third recess 83 and the fourth recess 84 and the column part. The steps formed between the third recess 83 and the fourth recess 84 and the column part can prevent the resin layer 90 from moving at least in the +X direction.In this configuration, the third recess 83 and the fourth recess 84 may correspond to the column. Even with such a configuration, a similar effect to that of Embodiments 2 to 4 can be achieved. E3. Modification 3:

[0052] In Embodiments 2 to 4 described above, the shapes of the third recess 83 and the fourth recess 84 correspond to circles in a plan view (shapes viewed in the +X direction). However, the shapes may correspond to any other shape, such as a rectangular shape and a polygon, instead of the circle, for example. The third recess 83 and the fourth recess 84 are formed in a conical shape whose cross-sectional area parallel to the YZ plane surface increases in the -X direction. However, the third recess 83 and the fourth recess 84 may be formed such that the cross-sectional area parallel to the YZ plane surface corresponds to a rectangular shape. Even with these configurations, a similar effect to that of Embodiments 2 to 4 is produced.

[0053] The present disclosure is not limited to the embodiments and modifications described above, and can be implemented in various configurations within the scope of the disclosure. For example, the technical features in the embodiments and modifications can be appropriately replaced or combined to solve part or all of the problems described above or to achieve part or all of the effects described above. If the technical features are not described as necessary in this specification, the features can be appropriately omitted.

Claims

[1] Fuel cell stack (100; 100a; 100b; 100c), comprising: a stack (20) having a plurality of stacked unit cells (10); a housing (40) which receives the stack (20); and an end plate (30; 30a; 30b; 30c) which is arranged outside the plurality of unit cells (10) with respect to the stack (20) in the stacking direction and in which fluid flow path holes (70) penetrating them in the stacking direction and a receiving groove (80) receiving a sealing element (SL) for sealing a part between the receiving groove (80) and the housing (40) are formed, wherein the end plate (30; 30a; 30b; 30c) covers an end face of the stack in the stacking direction and an end face of the housing (40) in the stacking direction and is fixed to the end face of the housing (40), the end plate (30; 30a; 30b; 30c) has: a metal member (31; 31a; 31b; 31c) formed with the fluid flow path holes (70), a first recess (81) and a second recess (82) continuous to the first recess (81), and a resin layer (90) continuously covering an inner peripheral wall surface of the fluid flow path holes (70), a surface facing the stack (20), a part including at least one outer peripheral end at the first recess (81), and the second recess (82) in the metal member, wherein the resin layer (90) is formed with the receiving groove (80) at a surface corresponding to the end face of the housing (40) at a part covering the part including at least the outer peripheral end at the first recess (81), the second recess (82) receives a part of the resin layer (90) to restrict the resin layer (90), the second recess (82) has a third recess (83) along the stacking direction at the outer peripheral end of the first recess (81), which is arranged along the stacking direction and is continuous to a part on an opposite side to the receiving groove (80), at least a part of the third recess (83) is formed along the stacking direction in such a way that it corresponds to a conical shape whose cross-sectional area gradually increases perpendicular to the stacking direction, starting from the stack along the stacking direction towards the end plate (30; 30a; 30b; 30c), and the entirety of the third recess (83) along the stacking direction is formed such that it corresponds to the conical shape. [2] Fuel cell stack (100; 100a; 100b; 100c), comprising: a stack (20) having a plurality of stacked unit cells (10); a housing (40) which receives the stack (20); and an end plate (30; 30a; 30b; 30c) which is arranged outside the plurality of unit cells (10) with respect to the stack (20) in the stacking direction and in which fluid flow path holes (70) penetrating them in the stacking direction and a receiving groove (80) receiving a sealing element (SL) for sealing a part between the receiving groove (80) and the housing (40) are formed, wherein the end plate (30; 30a; 30b; 30c) covers an end face of the stack in the stacking direction and an end face of the housing (40) in the stacking direction and is fixed to the end face of the housing (40), the end plate (30; 30a; 30b; 30c) has: a metal member (31; 31a; 31b; 31c) formed with the fluid flow path holes (70), a first recess (81) and a second recess (82) continuous to the first recess (81), and a resin layer (90) continuously covering an inner peripheral wall surface of the fluid flow path holes (70), a surface facing the stack (20), a part including at least one outer peripheral end at the first recess (81), and the second recess (82) in the metal member, wherein the resin layer (90) is formed with the receiving groove (80) at a surface corresponding to the end face of the housing (40) at a part covering the part including at least the outer peripheral end at the first recess (81), the second recess (82) receives a part of the resin layer (90) to restrict the resin layer (90), the second recess (82) has a fourth recess (84) along the stacking direction at the inner peripheral end of the first recess (81), which is arranged along the stacking direction and is continuous to a part on an opposite side to the receiving groove (80), at least a part of the fourth recess (84) is formed along the stacking direction in such a way that it corresponds to a conical shape whose cross-sectional area gradually increases perpendicular to the stacking direction, starting from the stack along the stacking direction towards the end plate (30; 30a; 30b; 30c), and the entirety of the fourth recess (84) along the stacking direction is formed such that it corresponds to the conical shape. [3] Fuel cell stack (100; 100a; 100b; 100c), comprising: a stack (20) having a plurality of stacked unit cells (10); a housing (40) which receives the stack (20); and an end plate (30; 30a; 30b; 30c) which is arranged outside the plurality of unit cells (10) with respect to the stack (20) in the stacking direction and in which fluid flow path holes (70) penetrating them in the stacking direction and a receiving groove (80) receiving a sealing element (SL) for sealing a part between the receiving groove (80) and the housing (40) are formed, wherein the end plate (30; 30a; 30b; 30c) covers an end face of the stack in the stacking direction and an end face of the housing (40) in the stacking direction and is fixed to the end face of the housing (40), the end plate (30; 30a; 30b; 30c) has: a metal member (31; 31a; 31b; 31c) formed with the fluid flow path holes (70), a first recess (81) and a second recess (82) continuous to the first recess (81), and a resin layer (90) continuously covering an inner peripheral wall surface of the fluid flow path holes (70), a surface facing the stack (20), a part including at least one outer peripheral end at the first recess (81), and the second recess (82) in the metal member, wherein the resin layer (90) is formed with the receiving groove (80) at a surface corresponding to the end face of the housing (40) at a part covering the part including at least the outer peripheral end at the first recess (81), the second recess (82) receives a part of the resin layer (90) to restrict the resin layer (90), the second recess (82) has a third recess (83) and a fourth recess (84), the third recess (83) is arranged along the stacking direction and is continuous along the stacking direction at the outer peripheral end of the first recess (81) to a part on an opposite side to the receiving groove (80), the entirety of the third recess (83) is formed along the stacking direction in such a way that it corresponds to a conical shape whose cross-sectional area gradually increases perpendicular to the stacking direction, starting from the stack along the stacking direction towards the end plate (30; 30a; 30b; 30c), the fourth recess (84) is arranged along the stacking direction and is continuous along the stacking direction at the inner peripheral end of the first recess (81) to a part on the opposite side to the receiving groove (80), and the entirety of the fourth recess (84) along the stacking direction is formed such that it corresponds to the conical shape.

Images