Fuel cell structure

Abstract

To provide a compact fuel cell structure capable of suppressing load loss when the temperature of a cell stack is increased.SOLUTION: A fuel cell structure 10 includes a cell stack 20 formed by stacking a plurality of cells 21, a fastening mechanism portion 30 that fastens the cell stack 20 during assembly in a compressed state from both sides in a third direction Z which is a stacking direction of the plurality of cells 21, and a load receiving mechanism portion 40 that receives a load in a compression release direction Z1 from the cell stack 20 compressed by the fastening mechanism portion 30, and the load receiving mechanism portion 40 is configured to receive a linear expansion load in the compression release direction Z1 caused by a reduction in compressive load by the fastening mechanism portion 30 when the temperature of the cell stack 20 is increased.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a fuel cell structure. [Background technology]

[0002] The following Patent Document 1 discloses a solid oxide fuel cell, which is one type of fuel cell structure. This fuel cell has a fastening structure that fastens a cell stack, which is made up of multiple stacked MEA cells, in a compressed state using multiple bolt members, multiple nut members, and multiple compression springs. In this conventional fastening structure, the bolt member is screwed into the nut member with the compression spring inserted into its shaft. This allows the ceramic compression spring to bear all of the load applied to fasten the bolt member and nut member during assembly.

[0003] This fuel cell is used in a high-temperature operating environment, for example, at temperatures exceeding 700°C, and when the temperature of the cell stack rises, the difference in linear expansion between the bolt members can cause a phenomenon known as "load loss," in which the load applied to the cell stack during assembly decreases. When load loss occurs, the compressive load applied to fasten the cell stack decreases, and current collection and gas sealing properties deteriorate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-126833 A Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of fuel cell structure, it is desirable to apply a compressive load to the cell stack in order to prevent misalignment of the components constituting the cell stack during transportation at room temperature, and therefore it is desirable to always apply a compressive load to the cell stack under conditions ranging from room temperature to high temperatures (operating temperatures). In the above-mentioned conventional fastening structure, the cell stack is compressed by a spring member, and the spring member bears the linear expansion load that occurs in the compression release direction when the temperature of the cell stack rises. In this case, since the spring member has both the function of compressing the cell stack and the function of bearing the linear expansion load, the load that the spring member bears becomes large, and it is necessary to make the spring member large or to increase the number of spring members. As a result, a problem of the fuel cell structure becoming large may occur. In addition, even if a ceramic compression spring that does not lose much strength under high temperature conditions is used, it is difficult to fundamentally solve such a problem.

[0006] The present invention has been made in view of the above problems, and aims to provide a small-sized fuel cell structure that can suppress load loss when the temperature of the cell stack rises. [Means for solving the problem]

[0007] One aspect of the present invention is A cell stack (20) formed by stacking a plurality of cells (21); A fastening mechanism that fastens the cell stack while compressing it from both sides in the stacking direction (Z) of the multiple cells. (30) and, A load receiving mechanism for receiving a load in a compression release direction (Z1) from the cell stack compressed by the fastening mechanism. (140) and, Equipped with The load receiving mechanism is configured to receive a linear expansion load (F) in the compression release direction, which is generated by a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack increases. R, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (141) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; The load receiving mechanism includes a cylinder (141) that is provided as the elastic element so as to be elastically deformable in the stacking direction, and a pressurized medium supply unit (143) that supplies a pressurized medium to an internal space (141a) of the cylinder, and is configured to apply a compressive load to the cell stack by utilizing the elastic deformation of the cylinder in the stacking direction when the pressurized medium is supplied from the pressurized medium supply unit to the internal space. , fuel cell structure (10C)、 is located. In addition, another aspect of the present invention is A cell stack (20) formed by stacking a plurality of cells (21); a fastening mechanism (30) that fastens the cell stack in a compressed state from both sides in a stacking direction (Z) of the plurality of cells; a load receiving mechanism (240) for receiving a load in a compression releasing direction (Z1) from the cell stack compressed by the fastening mechanism; Equipped with a linear expansion load (F) in the compression release direction, which is generated by a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack is increased, is received by the load receiving mechanism, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (241) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; a fuel cell structure (10D) in which the load-receiving mechanism includes a container (241) as the elastic element, the container being elastically deformable in the stacking direction, a thermal expansion material (M) that changes in volume with a change in temperature is contained in a storage space (241a) of the container, and the load-receiving mechanism is configured to apply a compressive load to the cell stack by utilizing elastic deformation of the container in the stacking direction when the temperature of the container is adjusted to a temperature range in which volume expansion of the thermal expansion material occurs; is located. Further, another aspect of the present invention is A cell stack (20) formed by stacking a plurality of cells (21); a fastening mechanism (30) that fastens the cell stack in a compressed state from both sides in a stacking direction (Z) of the plurality of cells; a load receiving mechanism (340) for receiving a load in a compression releasing direction (Z1) from the cell stack compressed by the fastening mechanism; Equipped with a linear expansion load (F) in the compression release direction, which is generated by a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack is increased, is received by the load receiving mechanism, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (341) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; the load-receiving mechanism includes a metal member (341) made of a shape memory alloy that is elastically deformable in the stacking direction due to a change in temperature as the elastic element, and is configured to apply a compressive load to the cell stack by utilizing the elastic deformation of the metal member in the stacking direction. is located. Effect of the Invention

[0008] In the fuel cell structure of the above aspect, the cell stack formed by stacking a plurality of cells is fastened in a state compressed from both sides by the fastening mechanism during assembly. Therefore, in the assembled state of the cell stack, the cell stack receives a compressive load from the fastening mechanism, while the fastening mechanism receives a load from the cell stack in a compression release direction, which is the opposite direction to the compression direction.

[0009] Here, since the cell stack is usually used under high temperature conditions, it expands and deforms when the temperature rises. At this time, if there is a large difference in linear expansion between the cell stack and the fastening mechanism, this may cause a decrease in the compressive load that the cell stack receives from the fastening mechanism. If this compressive load decreases, problems may occur in that the current collection performance and gas sealing performance of the cell stack decrease.

[0010] To address this problem, as in conventional fastening structures, the cell stack is compressed with a spring member and the spring member bears the linear expansion load that occurs in the compression release direction when the cell stack is heated, but this increases the load that the spring member must bear, requiring the use of larger spring members or an increase in their number, resulting in a larger fuel cell structure.

[0011] Therefore, the load-receiving mechanism is provided separately from the fastening mechanism in order to receive the load in the compression release direction from the cell stack compressed by the fastening mechanism. This load-receiving mechanism has the function of receiving the linear expansion load in the compression release direction that occurs due to a decrease in the compressive load by the fastening mechanism when the temperature of the cell stack increases. In other words, the role of receiving the linear expansion load, which is the increase in load when the temperature of the cell stack increases, is taken on by the load-receiving mechanism provided separately from the fastening mechanism that fastens the cell stack in a compressed state.

[0012] As a result, the load-receiving mechanism prevents load loss when the cell stack is heated, and the cell stack can be maintained in a desired compressed state, thereby preventing a decrease in the current collection and gas sealing properties of the cell stack. Furthermore, by having the load-receiving mechanism bear the linear expansion load that occurs in the direction of compression release when the cell stack is heated, even if a spring member is used for the fastening mechanism or the load-receiving mechanism, the load borne by the spring member can be kept low as a linear expansion load, which is an increment when the cell stack is heated, and the spring members can be made smaller and fewer in number than in the conventional fastening structure described above. As a result, it is possible to prevent the fuel cell structure from becoming large.

[0013] As described above, according to the above-mentioned aspect, it is possible to provide a small-sized fuel cell structure capable of suppressing load loss when the temperature of the cell stack increases.

[0014] In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view of a fuel cell structure according to a first embodiment, viewed obliquely from above. [Diagram 2] FIG. 2 is a side view of the fuel cell structure of FIG. 1; [Diagram 3] 3 is a cross-sectional view of each cell of the cell stack in FIG. 2. [Figure 4] 4 is a cross-sectional view taken along line IV-IV in FIG. 2 . [Diagram 5] 5 is a cross-sectional view for explaining the assembly of the fuel cell structure of FIG. 4. [Figure 6] 5 is a cross-sectional view for explaining the action of the load receiving mechanism of the fuel cell structure of FIG. 4. [Figure 7] 5 is a cross-sectional view of a fuel cell structure according to a second embodiment, the cross-sectional view corresponding to FIG. [Figure 8] 5 is a cross-sectional view corresponding to FIG. 4 of a fuel cell structure according to a third embodiment. [Figure 9] 5 is a cross-sectional view corresponding to FIG. 4 of a fuel cell structure according to a fourth embodiment. [Figure 10] 7 is a cross-sectional view corresponding to FIG. 4 of a fuel cell structure according to a fifth embodiment. [Figure 11] 10 is a cross-sectional view corresponding to FIG. 4 of a fuel cell structure according to a sixth embodiment. [Figure 12] FIG. 11 is a side view corresponding to FIG. 2 of the fuel cell structure of embodiment 7. [Figure 13] 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a fuel cell structure will be described with reference to the drawings.

[0017] In the drawings of this specification, unless otherwise specified, a first direction, which is the horizontal direction of a flat cell stack constituting a fuel cell structure, is indicated by an arrow X, a second direction, which is the vertical direction of this cell stack, is indicated by an arrow Y, and a third direction, which is the stacking direction of multiple cells in this cell stack, is indicated by an arrow Z.

[0018] (Embodiment 1) 1 and 2, a fuel cell structure 10 according to a first embodiment is a solid oxide fuel cell. This solid oxide fuel cell is also called a "SOFC (Solid Oxide Fuel Cell)" and is a high-temperature operating type fuel cell used under high-temperature conditions, such as an operating environment temperature exceeding 700°C.

[0019] The fuel cell structure 10 is a structure generally including a cell stack 20, a fastening mechanism 30, and a load-receiving mechanism 40.

[0020] The cell stack 20 is a flat-plate-like laminate formed by stacking a plurality of flat-plate-like cells 21 of the same shape in the third direction Z (see FIG. 2). The cells 21 are basic components for generating electricity. The shape of the cells 21 in a plan view in the third direction Z is substantially rectangular.

[0021] The fastening mechanism 30 serves to fasten the cell stack 20 alone in a state of being compressed from both sides in the third direction Z (see FIG. 2). The fastening mechanism 30 is configured to receive a load in a compression release direction Z1 (see FIG. 2) in which the compression of the cell stack 20 is released when fastened. The fastening mechanism 30 is composed of a bottom plate 31 provided to face the lower surface of the cell stack 20, an upper plate 32 provided to face the upper surface of the cell stack 20, a bolt member 33, and a nut member 36 and a collar 37 (see FIG. 4), which will be described later. However, the fastening mechanism 30 does not include a spring member as a component.

[0022] The bottom plate 31 and the top plate 32 are both for sandwiching the cell stack 20 from both sides in the third direction Z, and are configured as flat metal members large enough to cover the cell stack 20. The bolt members 33 are for applying axial force to the bottom plate 31 and the top plate 32 for compressing the cell stack 20, and are axial members extending with the third direction Z as their axial direction.

[0023] The load-receiving mechanism 40 is for receiving a load in the compression release direction Z1 from the cell stack 20 compressed by the fastening mechanism 30. This load-receiving mechanism 40 is configured to receive a linear expansion load in the compression release direction Z1 that occurs due to a reduction in the compressive load by the fastening mechanism 30 when the temperature of the cell stack 20 rises. This linear expansion load can occur due to a phenomenon in which the load applied to the cell stack 20 during assembly is reduced due to a linear expansion difference between the cell stack 20 and the fastening mechanism 30, that is, so-called "load loss."

[0024] In this embodiment, four load receiving mechanisms 40 are provided. The four load receiving mechanisms 40 are arranged so as to surround the cell stack 20 along the outer circumferential surface of the upper plate 32 in a plan view of the fuel cell structure 10 in the third direction Z (see FIG. 1).

[0025] The number and arrangement of the load-receiving mechanisms 40 are not limited to those shown in FIG. 1. It is preferable to arrange an appropriate number of the load-receiving mechanisms 40 at appropriate positions so that the linear expansion load generated in the linear expansion direction Z1 can be received in a balanced manner.

[0026] 3, each of the multiple cells 21 in the cell stack 20 is generally referred to as a "single cell" or a "fuel cell." Each cell 21 has an electrolyte 21a, and a fuel electrode (anode) 21b and an air electrode (cathode) 21c arranged on either side of the electrolyte 21a in the third direction Z. Typically, each cell 21 can be an ASC (anode supported cell) in which the electrolyte 21a, the fuel electrode 21b, and the air electrode 21c are all made of a ceramic base, or an MSC (metal supported cell) in which part of the fuel electrode 21b is changed to metal.

[0027] Separators 22 are disposed on both sides of each cell 21 in the third direction Z. That is, the separator 22 is interposed between two cells 21, and a plurality of cells 21 are stacked with the separator 22 sandwiched therebetween to form a cell stack 20 as a stack.

[0028] Each separator 22 is provided with a plurality of first flow paths 22a formed between the fuel electrode 21b and the separator 22, and a plurality of second flow paths 22b formed between the fuel electrode 21b and the separator 22. The plurality of first flow paths 22a are flow paths through which hydrogen flows as a fuel gas, and extend in the second direction Y while being arranged in parallel to each other. The plurality of second flow paths 22b are flow paths through which air flows as an oxidizing gas, and extend in the first direction X while being arranged in parallel to each other. The direction in which the first flow path 22a extends and the direction in which the second flow path 22b extends are not particularly limited, and the direction may be appropriately changed as necessary. For example, a structure in which the first flow path 22a extends in the first direction X, a structure in which the first flow path 22a extends in a direction different from the first direction X and the second direction Y, a structure in which the second flow path 22b extends in the second direction Y, a structure in which the second flow path 22b extends in a direction different from the first direction X and the second direction Y, or the like may be adopted. In addition, it is preferable to provide a current collecting material (not shown) between each cell 21 and each separator 22 in order to increase current collection efficiency.

[0029] Next, a specific configuration of the fastening mechanism 30 will be described.

[0030] 4, the bolt member 33 is a bolt member having a cylindrical shank 33a and a head 33b provided at one end of the shank 33a so as to exceed the outer diameter of the shank 33a. A male thread is formed on the outer periphery of the shank 33a. The shank 33a is divided into a first shank 34 on the head 33b side and a second shank 35 which is a portion closer to the tip side than the first shank 34.

[0031] The shaft portion 33a extends in the third direction Z so as to penetrate both the through hole 31a of the bottom plate 31 and the through hole 32a of the upper plate 32. The head portion 33b of the bolt member 33 is caught in a step portion 31b formed inside the through hole 31a of the bottom plate 31, thereby preventing the bolt member 33 from moving upward relative to the bottom plate 31.

[0032] The nut member 36 is an engagement portion provided on the bolt member 33 to compress the cell stack 20 in the third direction Z by utilizing the axial force of the bolt member 33. The nut member 36 is an engagement member separate from the bolt member 33, and is attached to the bolt member 33 by being screwed onto the first shaft portion 34 of the bolt member 33.

[0033] The nut member 36 has a through hole with a female thread formed on the inner surface, and when screwed onto the first shaft portion 34 of the bolt member 33, it functions to compress the cell stack 20 in the third direction Z in cooperation with the bolt member 33. Here, the nut member 36 is one form of an engagement portion that is provided on the bolt member 33 by screwing (engaging) with the bolt member 33.

[0034] When assembling the fastening mechanism 30, the shaft 33a of the bolt member 33 is inserted into the through hole 31a of the bottom plate 31 and the through hole 32a of the top plate 32, and the first shaft 34 is screwed into the nut member 36 inserted into the through hole 32a of the top plate 32. As a result, the fastening mechanism 30 is assembled in a state in which the bottom plate 31 and the top plate 32 are compressed so as to approach each other in the third direction Z.

[0035] When the fastening mechanism 30 is in an assembled state, a compressive load is applied to the cell stack 20 via the bottom plate 31 and the top plate 32, compressing the multiple cells 21 from both sides in the third direction Z. This compressive load can also be referred to as a fastening load that fastens the cell stack 20. At this time, the nut member 36 applies a load in the compressive direction to the cell stack 20, while receiving a load from the cell stack 20 in the linear expansion direction Z1, which is the opposite direction to the compression direction.

[0036] According to the fastening mechanism 30 having the above-described configuration, by compressing the cell stack 20, the contact between the cells 21 and the separators 22 can be improved to increase the current collection efficiency, and the sealing performance of each of the first flow paths 22a and the second flow paths 22b of the separator 22 can be improved to increase the gas sealing performance.

[0037] In order to position the shaft portion 33a of the bolt member 33 in the through hole 32a of the upper plate 32, it is preferable to use a collar 37 that engages with a step portion 32b formed inside the through hole 32a. At this time, the first shaft portion 34 of the bolt member 33 is inserted into the through hole 37a of the collar 37 and screwed into the nut member 36. The collar 37 is preferably made of an electrical insulating material (such as alumina) to ensure electrical insulation between the two poles of the cell stack 20.

[0038] At this time, of the shank 33a of the bolt member 33, a portion closer to the head 33b than the nut member 36, i.e., a portion between the head 33b and the nut member 36, is the first shank 34, and a portion on the tip side, i.e., a portion between the nut member 36 and a nut member 45 described below, is the second shank 35. In this embodiment, the first shank 34 of the bolt member 33 is a component of the fastening mechanism 30, while the second shank 35 is a component of the load receiving mechanism 40.

[0039] Next, a specific configuration of the load receiving mechanism 40 will be described.

[0040] As shown in FIG. 4, the load-receiving mechanism 40 includes the second shaft portion 35 of the bolt member 33, an outer collar 41, an inner collar 42, a washer 43, a pressure plate 44, a nut member 45, and a spring member 46 as an elastic element.

[0041] Both the outer collar 41 and the inner collar 42 are formed in a cylindrical shape. The inner collar 42, which has a smaller diameter than the outer collar 41, is housed inside the cylindrical outer collar 41. At this time, the space between the outer collar 41 and the inner collar 42 becomes a housing space for the spring member 46. The shaft portion 33a of the bolt member 33 is inserted into the cylindrical inner collar 42. The lower part of the inner collar 42 is inserted into the through hole 43a of the washer 43.

[0042] The spring member 46 is a compression coil spring interposed between the cell stack 20 and the nut member 45 so as to be elastically deformable in the third direction Z. The spring member 46 is assembled so that, when disposed in the accommodation space between the outer collar 41 and the inner collar 42, the upper end of the coil abuts against the pressing plate 44 and the lower end of the coil abuts against the washer 43 abutting against the upper surface 32c of the upper plate 32. The material of the spring member 46 is not particularly limited, but in order to keep costs low, it is preferable to form the spring member 46 using a wire made of a metal material. In addition, in order to prevent loss of load during long-term use at high temperatures, it is preferable to use ceramics such as silicon nitride as the material of the spring member 46.

[0043] The second shaft portion 35 of the bolt member 33 is configured to screw into the nut member 45 in a state where it is inserted into the through hole 44a of the pressing plate 44. The nut member 45 is an engagement portion provided on the bolt member 33 to compress the cell stack 20 in the third direction Z by utilizing the axial force of the bolt member 33. The nut member 45 is an engagement member separate from the bolt member 33, and is attached to the bolt member 33 by screwing into the second shaft portion 35 of the bolt member 33.

[0044] The nut member 45 has a through hole with a female thread formed on the inner surface, similar to the nut member 36, and is configured as a second engaging portion that engages with the second shaft portion 35 of the bolt member 33 separately from the nut member 36 when the nut member 36 is configured as a first engaging portion. The nut member 45 screws into the second shaft portion 35 of the bolt member 33, whereas the nut member 36 screws into the first shaft portion 34 of the bolt member 33. When the nut member 45 screws into the second shaft portion 35 of the bolt member 33, it functions to pressurize the cell stack 20 in cooperation with the bolt member 33. Here, the nut member 45 is one form of an engaging portion provided on the bolt member 33 by screwing (engaging) with the bolt member 33.

[0045] The load-receiving mechanism 40 is attached to the top of the upper plate 32 by screwing the nut member 45 onto the second shaft portion 35 of the bolt member 33 against the elastic biasing force of the spring member 46. At this time, the load-receiving mechanism 40 is configured to apply the elastic biasing force of the spring member 46 to the upper plate 32 of the fastening mechanism 30. Therefore, the load-receiving mechanism 40 applies a load in the compression direction to the cell stack 20 independently of the compression by the fastening mechanism 30.

[0046] 4, according to the fastening mechanism 30, when the nut member 36 is screwed onto the first shaft portion 34 of the bolt member 33, a compressive load is input to the cell stack 20 from the nut member 36 through a load input path A1 to the stepped portion 32b of the upper plate 32. Meanwhile, the nut member 36 receives a load in the direction opposite to the compressive direction from the cell stack 20 through a load receiving path A2 that is oriented in the opposite direction to the load input path A1.

[0047] In contrast, with the load receiving mechanism 40, when the nut member 45 is screwed onto the second shaft portion 35 of the bolt member 33, a load in the compressive direction is input from the nut member 45 to the upper surface 32c of the upper plate 32 through a load input path B1 that is independent of the load input path A1 of the fastening mechanism 30. Meanwhile, the nut member 45 receives a load in the direction opposite to the compressive direction from the cell stack 20 through a load receiving path B2 that is oriented in the opposite direction to the load input path B1.

[0048] Here, the load input path A1 of the fastening mechanism 30 is a path from the nut member 36 to the upper plate 32 via the collar 37, and the load receiving path A2 of the fastening mechanism 30 is a path in the opposite direction to the load input path A1, and is a path from the upper plate 32 to the nut member 36 via the collar 37. On the other hand, the load input path B1 of the load receiving mechanism 40 is a path from the nut member 45 to the upper plate 32 via the presser plate 44, the spring member 46 and the washer 43, and the load receiving path B2 of the load receiving mechanism 40 is a path in the opposite direction to the load input path B1, and is a path from the upper plate 32 to the nut member 45 via the washer 43, the spring member 46 and the presser plate 44. In FIG. 4, for convenience, the two paths A1 and A2 are shown by one arrow line, and the two paths B1 and B2 are shown by one arrow line.

[0049] At this time, the load input path A1 and the load input path B1 are parallel paths that enable independent load transmission, and the load receiving path A2 and the load receiving path B2 are parallel paths that enable independent load transmission.

[0050] In FIG. 4, the four paths A1, A2, B1, and B2 are all represented by schematic lines, however, this representation is merely schematic, and in reality, the four paths A1, A2, B1, and B2 are formed around the entire circumference of the shaft portion 33a of the bolt member 33.

[0051] 5, when assembling the components of the fuel cell structure 10, the fastening mechanism 30 is assembled as a first step before assembling the load-receiving mechanism 40. In this first step, first, with the cell stack 20 sandwiched between the bottom plate 31 and the top plate 32, the shaft 33a of the bolt member 33 is inserted sequentially into the through hole 31a of the bottom plate 31 and the through hole 32a of the top plate 32, and then the nut member 36 is screwed onto the first shaft 34 of the bolt member 33 to tighten it. As a result, the cell stack 20 is compressed from both sides in the third direction Z by being sandwiched between the bottom plate 31 and the top plate 32.

[0052] In the second step, following the first step, the load receiving mechanism 40 is assembled. In this second step, first, the washer 43, the inner collar 42, the spring member 46, the outer collar 41, and the pressing plate 44 are arranged on the axis L of the shaft portion 33a of the bolt member 33. Then, the nut member 45 is screwed onto the second shaft portion 35 of the bolt member 33 and tightened. As a result, the spring member 46 is compressed in the contracting direction, and the spring length in the third direction Z becomes shorter than the natural length. Then, the elastic biasing force of the spring member 46 at this time is applied to the upper surface 32c of the upper plate 32.

[0053] By adopting a procedure in which the second step is performed after the first step and the load receiving mechanism 40 is assembled after the fastening mechanism 30 is assembled, it is possible to prevent excessive force from being applied to the spring member 46.

[0054] In the load receiving mechanism 40, at least one of the outer collar 41 and the inner collar 42 is preferably configured as an auxiliary member for setting the spring length in the third direction Z when the spring member 46 is assembled. In this configuration, the dimension of the auxiliary member in the third direction Z is set according to the desired controlled length of the spring member 46 in the third direction Z, and when the nut member 45 is tightened to a predetermined tightenable position, the auxiliary member prevents the nut member 45 from moving toward the head 33b of the bolt member 33. According to this configuration, the length of the spring member 46 in the third direction Z can be automatically set to the controlled length by simply tightening the nut member 45, eliminating the need for load management of the spring member 46.

[0055] Furthermore, the auxiliary member is preferably configured so that its linear expansion coefficient in the third direction Z is lower than that of the bolt member 33. In this configuration, the auxiliary member is less likely to expand in the third direction Z than the bolt member 33 when the temperature rises. The "linear expansion coefficient" here indicates the amount of expansion / contraction per unit length per temperature when the length in the third direction Z changes due to a change in temperature. With this configuration, the bolt member 33 expands more in the third direction Z than the auxiliary member when the temperature rises, so that it is possible to prevent load loss, which would otherwise occur if the compressive load applied by the load receiving mechanism 40 to the cell stack 20 weakens due to the expansion of the auxiliary member.

[0056] In the fuel cell structure 10 having the above configuration, the cell stack 20 is heated by energization and used under high temperature conditions. For this reason, if a bolt member 33 made of a general metal material is used, the shaft portion 33a of the bolt member 33 is likely to expand in the third direction Z, which is the axial direction, when the temperature of the cell stack 20 rises. At this time, if the degree of expansion and deformation of the shaft portion 33a of the bolt member 33 in the linear expansion direction Z1 exceeds the degree of expansion and deformation of the cell stack 20 in the linear expansion direction Z1, the difference in linear expansion between the shaft portion 33a of the bolt member 33 and the cell stack 20 may cause a phenomenon called "load loss" in which the load in the compressive direction applied to the cell stack 20 during assembly decreases.

[0057] Therefore, in this embodiment, in order to suppress load loss that can occur when the temperature rises after the cell stack 20 is assembled in the fuel cell structure 10, a load receiving mechanism 40 is provided in addition to the fastening mechanism 30.

[0058] 6, when the shaft portion 33a of the bolt member 33 expands in the linear expansion direction Z1 relative to the head portion 33b during a temperature rise of the cell stack 20, the spring member 46 elastically deforms in response in the expanding direction so as to strengthen the pressure against the upper plate 32 that presses the cell stack 20. In other words, the spring member 46 expands in the third direction Z by an amount corresponding to the difference in linear expansion occurring between the shaft portion 33a of the bolt member 33 and the cell stack 20.

[0059] At this time, the load receiving mechanism 40 is configured to receive only the linear expansion load F, which is an increment of the load in the linear expansion direction Z1 that occurs when the temperature of the cell stack 20 rises, through the load receiving path B2, independently of the fastening mechanism 30. Therefore, even if a linear expansion difference occurs between the shaft portion 33a of the bolt member 33 and the cell stack 20 when the temperature of the cell stack 20 rises, the spring member 46 expands in the third direction Z, so that the linear expansion load F in the linear expansion direction Z1 can be received by the nut member 45 on the load receiving path B2. Even if the compressive load by the fastening mechanism 30 decreases due to this linear expansion difference and the load input weakens, the elastic biasing force by the spring member 46 can be applied to the upper plate 32. This ensures that the cell stack 20 is in a compressed state even when the temperature of the cell stack 20 rises, making it less likely that the load will fall off.

[0060] Next, the effects of the above-mentioned embodiment 1 will be described.

[0061] In the fuel cell structure 10 configured as described above, the cell stack 20 formed by stacking a plurality of cells 21 is fastened in a state compressed from both sides by the fastening mechanism 30 during assembly. Therefore, in the assembled state of the cell stack 20, the cell stack 20 receives a compressive load from the fastening mechanism 30, while the fastening mechanism 30 receives a load from the cell stack 20 in the compression release direction Z1.

[0062] In this embodiment, the load-receiving mechanism 40 is provided separately from the fastening mechanism 30 in order to receive a load in the compression release direction Z1 from the cell stack 20 compressed by the fastening mechanism 30. This load-receiving mechanism 40 has the function of receiving a linear expansion load F in the compression release direction Z1 that occurs due to a decrease in the compressive load by the fastening mechanism 30 when the temperature of the cell stack 20 increases. In other words, the role of receiving the linear expansion load F, which is an increase in load when the temperature of the cell stack 20 increases, is taken on by the load-receiving mechanism 40, which is provided separately from the fastening mechanism 30 that fastens the cell stack 20 in a compressed state.

[0063] As a result, the load receiving mechanism 40 prevents load loss when the temperature of the cell stack 20 rises, and the cell stack 20 can be maintained in a desired compressed state, thereby suppressing deterioration in the current collection and gas sealing properties of the cell stack 20. Furthermore, by having the load receiving mechanism 40 take on the role of receiving the linear expansion load F that occurs in the compression release direction Z1 when the temperature of the cell stack 20 rises, even if a spring member 46 is used for the load receiving mechanism 40, the load received by the spring member 46 can be kept low as the linear expansion load F, which is the increment when the temperature of the cell stack 20 rises, and the spring members 46 can be made smaller and the number of spring members 46 can be reduced. As a result, it is possible to prevent the fuel cell structure 10 from becoming large.

[0064] Therefore, according to the above-described first embodiment, it is possible to provide a small-sized fuel cell structure 10 capable of suppressing load loss when the temperature of the cell stack 20 increases.

[0065] According to the above-described first embodiment, in the fastening mechanism 30, the axial force of the bolt member 33 can be used to compress the cell stack 20, and a nut member 36 that screws into the first shaft portion 34 of the bolt member 33 can be used. In the load receiving mechanism 40, the axial force of the bolt member 33 can be used to compress the cell stack 20, and a nut member 45 that screws into the second shaft portion 35 of the bolt member 33 can be used. In this case, both the nut member 36 and the nut member 45 are provided to the bolt member 33 by being screwed into the bolt member 33, and the assembly operation to the bolt member 33 can be easily performed.

[0066] According to the above-mentioned embodiment 1, the fastening mechanism 30 does not use any elastic element such as a spring member to fasten the cell stack 20 in a compressed state, but uses substantially only the bolt member 33 and the nut member 36, thereby simplifying the structure of the fastening mechanism 30.

[0067] According to the above-mentioned embodiment 1, by making the second shaft portion 35, which is part of the bolt member 33 of the fastening mechanism portion 30, serve also as the load receiving mechanism portion 40, it is effective in reducing the number of parts of each of the fastening mechanism portion 30 and the load receiving mechanism portion 40.

[0068] Hereinafter, other embodiments related to the above-mentioned embodiment 1 will be described with reference to the drawings. In the other embodiments, the same elements as those in the above-mentioned embodiment 1 are denoted by the same reference numerals, and the description of the same elements will be omitted.

[0069] (Embodiment 2) 7, the fuel cell structure 10A of the second embodiment has a fastening mechanism 130 having a structure different from that of the fastening mechanism 30 of the first embodiment. In this fastening mechanism 130, a shaft member 133 is used instead of the bolt member 33. As in the case of the fastening mechanism 30, the fastening mechanism 130 is assembled before the load receiving mechanism 40 is assembled.

[0070] In the fastening mechanism 130, the shaft portion 133a of the shaft member 133 is a long shaft portion extending in the third direction Z so as to penetrate the through-hole 32a of the upper plate 32. The shaft member 133 is a flanged shaft member having a disk-shaped flange portion 136 formed by partially expanding the axial circumference of the shaft portion 133a. The shaft portion 133a of the shaft member 133 has a first shaft portion 134 and a second shaft portion 135 extending from the flange portion 136 in the third direction Z so as to move away from each other.

[0071] The flange portion 136 is used in place of the nut member 36 of the first embodiment, and has the same function as the nut member 36. The flange portion 136 is an expanded diameter portion of the shaft portion 133a, and is an engagement portion that is integrally provided on the shaft member 133 in order to compress the cell stack 20 in the third direction Z by utilizing the axial force of the shaft member 133. Here, the flange portion 136 is one form of an engagement portion that is provided on the shaft member 133 by partially expanding the diameter of the shaft portion 133a of the shaft member 133.

[0072] The first shaft portion 134 has a male thread formed on the outer periphery only of its extended tip portion (one end of the shaft portion 133a), while the bottom plate 31 is provided with an engagement hole 31c having a female thread formed on its inner periphery into which the first shaft portion 134 can be screwed. The second shaft portion 135 has a male thread formed on the outer periphery only of its extended tip portion (the other end of the shaft portion 133a). The second shaft portion 135 is configured to be screwed into the nut member 45, similar to the second shaft portion 35 of the first embodiment.

[0073] The nut member 45, when screwed onto the second shaft portion 135, functions to pressurize the cell stack 20 in cooperation with the shaft member 133. Here, the nut member 45 is one form of an engagement portion that is provided on the shaft member 133 by screwing (engaging) with the shaft member 133.

[0074] When assembling the fastening mechanism 130, with the cell stack 20 sandwiched between the bottom plate 31 and the top plate 32, the first shaft portion 134 of the shaft member 133 is inserted into the through hole 32a of the top plate 32 and screwed into the engagement hole 31c of the bottom plate 31. This makes it possible to compress the bottom plate 31 and the top plate 32 so as to approach each other in the third direction Z. At this time, the flange portion 136 applies a downward pressing load to the step portion 32b of the top plate 32 via the collar 37. This applies a compressive load to the cell stack 20 that compresses the multiple cells 21.

[0075] The other configurations are the same as those in the first embodiment.

[0076] According to the fuel cell structure 10A of the second embodiment, by using the shaft member 133 with a flange instead of the bolt member 33 of the first embodiment, a part corresponding to the nut member 36 is not required. This makes it possible to reduce the number of parts and simplify the assembly work. In addition, since it is only necessary to cut male threads on both ends of the shaft portion 133a, the load of the processing work can be reduced.

[0077] In addition, the same effects as those of the first embodiment are achieved.

[0078] In a modification related to the above-mentioned embodiment 2, the first shaft portion 134 of the shaft member 133 can be configured as a cylindrical shaft portion having no male thread formed on its outer periphery, and the engagement hole 31c of the bottom plate 31 can be configured as a cylindrical shaft portion having no female thread formed on its inner periphery. In this case, the shaft member 133 is preferably fixed to the bottom plate 31 by press-fitting the first shaft portion 134 into the engagement hole 31c of the bottom plate 31, or by welding the first shaft portion 134 in a state where it is inserted into the engagement hole 31c of the bottom plate 31. This makes it possible to omit the thread cutting process in the case of embodiment 2.

[0079] In another modification related to the above-mentioned second embodiment, a portion such as a flange portion 136 may be provided at the extending tip portion of the second shaft portion 135 of the shaft member 133 instead of the nut member 45. This makes it possible to omit the part corresponding to the nut member 45 of the second embodiment, thereby reducing the number of parts and simplifying the assembly work.

[0080] (Embodiment 3) 8, the fuel cell structure 10B of embodiment 3 has a fastening mechanism 230 whose structure differs from that of the fastening mechanism 30 of embodiment 1. In this fastening mechanism 230, a shaft member 233 is used instead of the bolt member 33, and a locking pin 236 is used instead of the nut member 36. As in the case of the fastening mechanism 30, the fastening mechanism 230 is assembled before the load receiving mechanism 40 is assembled.

[0081] The shaft portion 233a of the shaft member 233 is a long shaft portion extending in the third direction Z so as to penetrate both the through hole 31a of the bottom plate 31 and the through hole 32a of the upper plate 32. The shaft portion 133a has a first shaft portion 234 having no male thread formed on its outer periphery, and a second shaft portion 235 having a male thread formed on its outer periphery. The first shaft portion 234 is configured so that a locking pin 236 can be attached to its outer periphery.

[0082] The locking pin 236 has the same function as the nut member 36 of the first embodiment. The locking pin 236 is a flat plate-shaped member having an opening 236a capable of accommodating the first shaft portion 234 of the shaft member 233, and a plurality of locking pieces 236b that are provided in the circumferential direction D1 so as to surround the opening 236a and are elastically deformable in the radial direction D2. The locking pin 236 is configured such that the opening diameter of the opening 236a is slightly smaller than the shaft diameter of the first shaft portion 234. The locking pin 236 is locked to the outer periphery of the first shaft portion 234 by inserting the first shaft portion 234 of the shaft member 233 into the opening 236a.

[0083] The locking pin 236 is an engagement portion provided on the shaft member 233 in order to compress the cell stack 20 in the third direction Z by utilizing the axial force of the shaft member 233. The locking pin 236 is attached to the first shaft portion 234, thereby restricting the relative movement in the third direction Z between the first shaft portion 234 and the locking pin 236. Furthermore, the locking pin 236 attached to the first shaft portion 234 is removed from the first shaft portion 234 by being pulled out against the elastic biasing force. Here, the locking pin 236 is one form of an engagement portion provided on the shaft member 233 by being attached to the shaft member 233.

[0084] When assembling the fastening mechanism 230, with the cell stack 20 sandwiched between the bottom plate 31 and the top plate 32, a locking pin 236 is attached to the tip of a first shaft portion 234 of the shaft member 233, and this first shaft portion 234 is inserted sequentially into the through hole 31a of the bottom plate 31 and the through hole 32a of the top plate 32. Thereafter, by attaching another locking pin 236 to the outer periphery of the first shaft portion 234 so as to apply a downward pressing load to the step portion 32b of the top plate 32 via the collar 37, it is possible to compress the bottom plate 31 and the top plate 32 so as to approach each other in the third direction Z. As a result, a compressive load is applied to the cell stack 20 to compress the multiple cells 21.

[0085] When the nut member 45 is screwed onto the second shaft portion 235 of the shaft member 233, the nut member 45 cooperates with the shaft member 233 to pressurize the cell stack 20. Here, the nut member 45 is one form of an engagement portion that is provided on the shaft member 233 by screwing (engaging) with the shaft member 233.

[0086] The other configurations are the same as those in the first embodiment.

[0087] According to the fuel cell structure 10B of the third embodiment, the fastening mechanism 230 can be attached by a simple operation of inserting the first shaft portion 234 of the shaft member 233 into the opening 236a of the locking pin 236.

[0088] In addition, the same effects as those of the first embodiment are achieved.

[0089] In a modification related to the above-mentioned embodiment 3, an engagement member such as a locking pin 236 may be attached to the extending tip portion of the second shaft portion 235 of the shaft member 233 instead of the nut member 45. This makes it possible to perform the assembly operation of the load receiving mechanism 40 by a simple operation using the locking pin 236.

[0090] (Embodiment 4) 9, the fuel cell structure 10C of the embodiment 4 has a load receiving mechanism 140 having a structure different from that of the load receiving mechanism 40 of the embodiment 1. The load receiving mechanism 140 is assembled after the fastening mechanism 30 is assembled, similar to the load receiving mechanism 40.

[0091] The load receiving mechanism 140 includes a cylindrical pneumatic cylinder 141 and an air supply pump 143 connected to an internal space 141a inside the cylinder of the pneumatic cylinder 141 via a connection pipe 142 so as to be able to supply air.

[0092] The pneumatic cylinder 141 is an elastic element interposed between the cell stack 20 and the nut member 45 so as to be elastically deformable in the third direction Z. The pneumatic cylinder 141 is configured as a cylinder in which at least a bottom surface portion 141b is elastically deformable in the third direction Z in order to pressurize the cell stack 20. The pneumatic cylinder 141 is assembled so that the bottom surface portion 141b abuts against the upper surface 32c of the upper plate 32 by screwing the nut member 45 onto the second shaft portion 35 of the bolt member 33 that penetrates the pneumatic cylinder 141 in the third direction Z. The air supply pump 143 is a pressurizing medium supply unit that supplies air, which is a pressurizing medium, to the internal space 141a of the pneumatic cylinder 141. The load receiving mechanism unit 140 is configured to apply a compressive load to the cell stack 20 by supplying air from the air supply pump 143 to the internal space 141a.

[0093] In this load receiving mechanism 140, a spring structure utilizing air supplied from an air supply pump 143, a so-called "air spring," is used instead of the spring member 46 of the first embodiment. The bottom surface portion 141b of the pneumatic cylinder 141 is elastically deformed downward by controlling the air supply pump 143. This enables the load receiving mechanism 140 to apply a compressive load to the upper plate 32 so that no loss of load occurs when the temperature of the cell stack 20 increases. Similarly to the load receiving mechanism 40 of the first embodiment, the load receiving mechanism 140 can receive, by the pneumatic cylinder 141, a linear expansion load F in the linear expansion direction Z1 that occurs when the temperature of the cell stack 20 increases.

[0094] The other configurations are the same as those in the first embodiment.

[0095] According to the fuel cell structure 10C of the fourth embodiment, the compressive load applied to the upper plate 32 in the load receiving mechanism 140 can be adjusted by controlling the air pressure with the air supply pump 143.

[0096] In a modified example related to the above-mentioned embodiment 4, instead of using the air pressure generated by the air supplied to the pneumatic cylinder 141 to generate a compressive load to be applied to the cell stack 20, the compressive load to be applied to the cell stack 20 may be generated by using the hydraulic pressure generated by supplying hydraulic oil, which is a pressurized medium, to the hydraulic cylinder.

[0097] In addition, the same effects as those of the first embodiment are achieved.

[0098] (Embodiment 5) 10, the fuel cell structure 10D of the embodiment 5 has a load receiving mechanism 240 having a different structure from the load receiving mechanism 40 of the embodiment 1. The load receiving mechanism 240 is assembled after the fastening mechanism 30 is assembled, similar to the load receiving mechanism 40.

[0099] The load receiving mechanism 240 includes a container 241 having a container space 241a with a circular cross section, and is configured to store a thermal expansion material M in the container space 241a. The thermal expansion material M is a material that undergoes a volume change in response to a temperature change in a given temperature range. Although there are no particular limitations on the type of the thermal expansion material M, it is typically preferable to use a material that has a property of increasing its volume by changing its phase from liquid to gas when it receives heat.

[0100] The storage container 241 is an elastic element interposed between the cell stack 20 and the nut member 45 so as to be elastically deformable in the third direction Z. The storage container 241 is configured as an elastic container in which at least a bottom surface portion 241b is elastically deformable in the third direction Z. The storage container 241 is assembled so that the bottom surface portion 241b abuts against the upper surface 32c of the upper plate 32 by screwing the nut member 45 onto the second shaft portion 35 of the bolt member 33 that penetrates the storage container 241 in the third direction Z.

[0101] According to this load receiving mechanism 240, by adjusting the temperature of the storage container 241 to a temperature range where the volume expansion of the thermal expansion material M occurs, the thermal expansion material M in the storage space 241a expands in volume by receiving heat, and the bottom surface 241b of the storage container 241 elastically deforms downward. At this time, the load receiving mechanism 240 can apply a compressive load from the bottom surface 241b of the storage container 241 to the upper plate 32 so that no load loss occurs when the temperature of the cell stack 20 increases. In addition, the load receiving mechanism 240 can receive the linear expansion load F generated in the linear expansion direction Z1 when the temperature of the cell stack 20 increases, by the storage container 241.

[0102] The other configurations are the same as those in the first embodiment.

[0103] According to the fuel cell structure 10D of the fifth embodiment, it becomes possible to apply a compressive load to the upper plate 32 in the load receiving mechanism 240 by utilizing the volume expansion of the thermal expansion material M due to the temperature rise of the cell stack 20.

[0104] In addition, the same effects as those of the first embodiment are achieved.

[0105] (Embodiment 6) 11, in the fuel cell structure 10E of the sixth embodiment, the structure of the load receiving mechanism 340 is different from that of the load receiving mechanism 40 of the first embodiment. The load receiving mechanism 340 is assembled after the fastening mechanism 30 is assembled, similar to the load receiving mechanism 40.

[0106] The load receiving mechanism 340 includes a cylindrical metal member 341, which is made of a shape memory alloy that is elastically deformable in the third direction Z due to a change in temperature. The shape memory alloy is a known material, and has the property of shrinking in the third direction Z when heated in an attempt to return to its original shape.

[0107] The metal member 341 is assembled such that a bottom portion 341a thereof abuts against an upper surface 32c of the upper plate 32 by screwing a nut member 45 onto a second shaft portion 35 of a bolt member 33 that penetrates the metal member 341 in the third direction Z. The metal member 341 is an elastic element that is interposed between the cell stack 20 and the nut member 45 so as to be elastically deformable in the third direction Z.

[0108] According to this load receiving mechanism 340, the metal member 341 is elastically deformed by heating so as to contract in the third direction Z. At this time, the load receiving mechanism 340 can apply a compressive load from the bottom 341a of the metal member 341 to the upper plate 32 so as not to cause load loss when the temperature of the cell stack 20 increases. In addition, the load receiving mechanism 340 can receive, by the metal member 341, a linear expansion load F that occurs in the linear expansion direction Z1 when the temperature of the cell stack 20 increases.

[0109] The other configurations are the same as those in the first embodiment.

[0110] According to the fuel cell structure 10E of the sixth embodiment, it becomes possible to apply a compressive load to the upper plate 32 in the load receiving mechanism 340 by utilizing the elastic deformation of the metal member 341 in the third direction Z.

[0111] In addition, the same effects as those of the first embodiment are achieved.

[0112] (Embodiment 7) 12, in the fuel cell structure 10F of embodiment 7, the structure of the fastening mechanism 330 is different from that of the fastening mechanism 30 of embodiment 1, and the structure of the load receiving mechanism 440 is different from that of the load receiving mechanism 40 of embodiment 1. The fastening mechanism 330 and the load receiving mechanism 440 are assembled at the same time.

[0113] The fastening mechanism 330 fastens the cell stack 20 in a state in which it is compressed from both sides in the third direction Z, similar to the fastening mechanism 30. The fastening mechanism 330 includes a base member 331 that supports the bottom plate 31 from below, and a clamp member 332. The clamp member 332 has a pressure member 333 for sandwiching the cell stack 20 between the base member 331 and the clamp member 332. The clamp member 332 is assembled with the bottom plate portion 441a of the pressing member 441 fitted in the recess 333a of the pressure member 333 (see FIG. 13). Therefore, the pressing member 441 is assembled simultaneously with the clamp member 232 with the bottom plate portion 441a pressed from above by the recess 333a of the pressing member 333.

[0114] The clamp member 332 employs a so-called "lever type" or "cam type" clamp structure, and is configured so that this clamp structure makes it possible to vary the distance in the third direction Z between the pressure portion 333 and the base member 331 in conjunction with the operation of a peripheral operation member (not shown). With this configuration, it is possible to switch between a clamping operation in which the cell stack 20 is clamped and a clamping release operation in which the clamping of the cell stack 20 is released in accordance with the movement of the pressure portion 333 of the clamp member 332 in the third direction Z.

[0115] When attached to the clamp member 332, the fastening force of this clamp member 332 is input to the cell stack 20 via the pressure section 333. This applies a compressive load to the cell stack 20, compressing the multiple cells 21 from both sides in the third direction Z. At this time, the pressure section 333 of the clamp member 332 applies a load in the compression direction to the cell stack 20, while also receiving a load from the cell stack 20 in the linear expansion direction Z1, which is the opposite direction to the compression direction.

[0116] The load receiving mechanism 440 is for receiving a linear expansion load F in the compression release direction Z1 that occurs due to a decrease in the compression load applied by the fastening mechanism 330 when the temperature of the cell stack 20 increases. The load receiving mechanism 440 includes a pressing member 441 and a plurality of spring members 442. Each of the plurality of spring members 442 is interposed between the pressing member 441 and the upper plate 32, and is pressed by the pressing member 441. Therefore, by assembling the pressing member 441, the elastic biasing force of each spring member 442 is applied as a pressure force to the upper surface 32c of the upper plate 32 via the bottom plate portion 441a.

[0117] When the clamp member 332 expands in the linear expansion direction Z1 due to the difference in linear expansion from the cell stack 20 when the temperature of the cell stack 20 increases, the spring member 442 elastically deforms in the expansion direction in response to this. That is, the spring member 442 expands in the third direction Z by an amount equal to the difference in linear expansion between the clamp member 332 and the cell stack 20. This ensures that the compressed state is maintained even when the temperature of the cell stack 20 increases, making it less likely that loss of load will occur.

[0118] The other configurations are the same as those in the first embodiment.

[0119] According to the fuel cell structure 10F of the seventh embodiment, the linear expansion load generated in the load receiving mechanism 440 in the linear expansion direction Z1 due to a temperature rise of the cell stack 20 can be received by the pressing member 441. Furthermore, compared to the first embodiment, the configurations of the fastening mechanism 330 and the load receiving mechanism 440 can be simplified.

[0120] In addition, the same effects as those of the first embodiment are achieved.

[0121] The present invention is not limited to the exemplary embodiment described above, and various applications and modifications are possible without departing from the scope of the present invention. For example, the following embodiments can be implemented by applying the above-described embodiment.

[0122] In the above-described embodiments, a solid oxide fuel cell having a cell stack 20 has been illustrated, but the features of each embodiment can also be applied to other types of fuel cells (e.g., molten carbonate fuel cells having a relatively high operating temperature). [Explanation of symbols]

[0123] 10, 10A, 10B, 10C, 10D, 10E, 10F... fuel cell structure, 20... cell stack, 21... cell, 30, 130, 230, 330... fastening mechanism, 33... bolt member (shaft member), 36... nut member (engagement portion, first engagement portion), 40, 140, 240, 340, 440... load receiving mechanism, 41... outer collar (auxiliary member), 42... inner collar (auxiliary member), 45... nut member (second engagement portion), 46... spring member (elastic element), 133... shaft member, 13 6... flange portion (engagement portion, first engagement portion), 141... pneumatic cylinder (elastic element, cylinder), 141a... internal space, 143... pneumatic pump (pressurized medium supply portion), 233... shaft member, 236... locking pin (engagement portion, first engagement portion), 236a... opening, 236b... locking piece, 241... storage container (elastic element), 241a... storage space, 341... metal member (elastic element), D1... circumferential direction, D2... radial direction, F... linear expansion load, M... thermal expansion material, Z... third direction (stacking direction), Z1... compression release direction

Claims

1. A cell stack (20) formed by stacking a plurality of cells (21); a fastening mechanism (30) that fastens the cell stack in a compressed state from both sides in the stacking direction (Z) of the plurality of cells; a load receiving mechanism (140) for receiving a load in a compression release direction (Z1) from the cell stack compressed by the fastening mechanism; Equipped with a linear expansion load (F) in the compression release direction, which is generated due to a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack is increased, is received by the load receiving mechanism, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (141) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; The load-receiving mechanism includes a cylinder (141) that is elastically deformable in the stacking direction as the elastic element, and a pressurized medium supply unit (143) that supplies pressurized medium to an internal space (141a) of the cylinder, and is configured to apply a compressive load to the cell stack by utilizing the elastic deformation of the cylinder in the stacking direction when the pressurized medium is supplied from the pressurized medium supply unit to the internal space.

2. A cell stack (20) formed by stacking a plurality of cells (21), a fastening mechanism (30) that fastens the cell stack in a compressed state from both sides in the stacking direction (Z) of the plurality of cells; a load receiving mechanism (240) for receiving a load in a compression release direction (Z1) from the cell stack compressed by the fastening mechanism; Equipped with a linear expansion load (F) in the compression release direction, which is generated due to a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack is increased, is received by the load receiving mechanism, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (241) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; The load-receiving mechanism includes a storage container (241) that is elastically deformable in the stacking direction as the elastic element, a thermal expansion material (M) that undergoes a volume change with temperature change is stored in the storage space (241a) of the storage container, and the fuel cell structure (10D) is configured to apply a compressive load to the cell stack by utilizing the elastic deformation of the storage container in the stacking direction when the temperature of the storage container is adjusted to a temperature range in which volume expansion of the thermal expansion material occurs.

3. A cell stack (20) formed by stacking a plurality of cells (21), a fastening mechanism (30) that fastens the cell stack in a compressed state from both sides in the stacking direction (Z) of the plurality of cells; a load receiving mechanism (340) for receiving a load in a compression release direction (Z1) from the cell stack compressed by the fastening mechanism; Equipped with a linear expansion load (F) in the compression release direction, which is generated due to a reduction in the compression load applied by the fastening mechanism when the temperature of the cell stack is increased, is received by the load receiving mechanism, the fastening mechanism portion has an axial member (33) extending in a stacking direction (Z) of the plurality of cells in the cell stack, and an engagement portion (36) provided on the axial member for compressing the cell stack by utilizing an axial force of the axial member, the load-receiving mechanism has, when the engaging portion of the fastening mechanism is defined as a first engaging portion, a second engaging portion (45) provided on the shaft member separately from the first engaging portion, and an elastic element (341) interposed between the cell stack and the second engaging portion so as to be elastically deformable in the stacking direction, and is configured to apply a compressive load to the cell stack by utilizing an elastic biasing force of the elastic element; The load-receiving mechanism portion is configured to include a metal member (341) made of a shape memory alloy that is elastically deformable in the stacking direction due to temperature changes as the elastic element, and to apply a compressive load to the cell stack by utilizing the elastic deformation of the metal member in the stacking direction.

4. The fuel cell structure according to any one of claims 1 to 3, wherein the load-receiving mechanism portion has an auxiliary member (41, 42) for setting the spring length in the stacking direction when assembling the compression coil spring, with the elastic element being a compression coil spring.

5. 5. The fuel cell structure according to claim 4, wherein the auxiliary member is configured so as to have a linear expansion coefficient in the stacking direction lower than that of the shaft member.

6. 6. The fuel cell structure according to claim 1, wherein the shaft member is a bolt member (33), and the engagement portion is a nut member (36) that is provided on the bolt member by being screwed into the bolt member.

7. The fuel cell structure according to any one of claims 1 to 5, wherein the shaft member has an expanded diameter portion (136) formed by partially expanding the axial circumference of the shaft portion (133a), and the engagement portion is the expanded diameter portion of the shaft member.

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