Fuel battery stack

Abstract

To provide a fuel battery stack including a fastening structure capable of suppressing a capacity increase or a weight increase.SOLUTION: A fuel battery stack comprises: a cell laminate in which a tabular fuel battery cell is laminated in a thickness direction; a base plate which is disposed in one end of the cell laminate in a lamination direction; a cover skirt which is a cylindrical member having both opened ends, of which one end is fixed to the base plate and which extends from the base plate in the lamination direction and encloses the cell laminate; and a pressing member including a plurality of crosspieces and fixed to a plurality of support parts protruding from an inner wall of the cover skirt in an inside direction of the cover skirt. The pressing member directly or indirectly presses the cell laminate from the other end side in the lamination direction in a state where the pressing member is fixed to the support parts.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fuel cell stack.

Background Art

[0002] A fuel cell stack has a structure in which plate-shaped unit cells and separators are alternately stacked, and in order to suppress an increase in the internal resistance of the battery due to the stacking, it is necessary to clamp the cell stack at a predetermined pressure. Patent Document 1 discloses a clamping structure in which both ends of a cell stack are sandwiched between a pair of end plates, a tie rod is inserted through a through hole of the end plate, and the end plate is clamped using clamping members from both ends of the tie rod.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the clamping structure of the above document, since the tie rod is installed outside the cell stack in the stacking direction view, the dimensions of the end plate increase by the amount of the tie rod provided. Further, the longer the length between a pair of tie rods facing each other with the cell stack interposed therebetween, that is, the longer the beam length of the end plate, the greater the bending stress applied to the end plate due to the clamping force of the tie rod and the reaction force from the cell stack. In order to suppress deformation due to bending stress, there are methods such as increasing the plate thickness of the end plate or using a high-rigidity material, but these will lead to an increase in the volume and weight of the fuel cell stack.

[0005] Therefore, an object of the present invention is to provide a fuel cell stack having a clamping structure capable of suppressing an increase in volume and weight.

Means for Solving the Problems

[0006] According to an aspect of the present invention, there is provided a fuel cell stack including a cell stack in which flat fuel cell cells are stacked in the thickness direction, a base plate disposed at one end in the stacking direction of the cell stack, and a cylindrical member having openings at both ends, one end of which is fixed to the base plate and which extends in the stacking direction from the base plate and surrounds the cell stack, a cover skirt, a plurality of crossbars, and a pressing member fixed to a plurality of support portions protruding from the inner wall of the cover skirt toward the inner side of the cover skirt, wherein the pressing member presses the cell stack directly or indirectly from the other end side in the stacking direction while being fixed to the support portions.

Advantages of the Invention

[0007] According to the above aspect, it is possible to provide a fuel cell stack having a tightening structure capable of suppressing an increase in volume and weight.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] [First Embodiment] FIG. 1 is an exploded perspective view of a fuel cell stack 1 according to the present embodiment. In the following description, the X direction in the figure is the horizontal direction, the Y direction is the vertical direction, and the Z direction is the vertical direction or the stacking direction.

[0011] The fuel cell stack 1 includes a cell stack 2, a base plate 4, an end plate 3, an insulating member 5, a cover skirt 6, and a pressing member 8.

[0012] The cell stack 2 includes a battery portion 2A in which flat fuel cell cells are stacked in the thickness direction thereof, and an end plate 3 disposed at the upper end in the stacking direction of the battery portion 2A.

[0013] The base plate 4 is disposed at the lower end in the stacking direction of the cell stack 2. In the present embodiment, the base plate 4 functions as a lower end plate, but the present invention is not limited thereto. For example, a configuration in which a cell stack 2 having a pair of end plates 3 disposed at the upper and lower ends of the battery portion 2A is placed on the base plate 4 may be adopted.

[0014] The cover skirt 6 is a cylindrical member having openings at both upper and lower ends. One end thereof is fixed to the base plate 4 with bolts or the like (not shown), extends in the stacking direction from the base plate 4, and surrounds the cell stack 2. The upper end opening of the cover skirt 6 is closed by bolting a lid (not shown). Further, a plurality of support portions 7 protruding inward are provided on the inner wall of the cover skirt 6. The fuel cell stack 1 of the present embodiment has a so-called open cathode structure, and the cover skirt 6 also functions as an outer wall for constituting the open cathode structure.

[0015] The insulating member 5 is a member for preventing a short circuit between the cell stack 2 and the cover skirt 6, and is formed of an insulator.

[0016] The pressing member 8 includes a plurality of bars 8A and 8B, and the ends of the respective bars 8A and 8B are fixed to the support portion 7. Then, the pressing member 8 presses the cell stack from the other end side in the stacking direction while being fixed to the support portion 7. Note that the vertical relationship between the support portion 7 and the pressing member 8 may be either on top, but in the present embodiment, the pressing member 8 is fixed to the lower surface of the support portion 7 (that is, the same side as the cell stack 2 in the stacking direction). The reason therefor will be described later.

[0017] FIG. 2 is a top view (the lid is omitted) of the fuel cell stack 1.

[0018] The pressing member 8 has a shape in which three horizontal bars 8A and three vertical bars 8B are arranged in a lattice pattern. The method of fixing the pressing member 8 to the support portion 7 is, for example, bolt fastening using fastening bolt holes (hereinafter also referred to as fastening holes) 10 provided in the support portion 7 and fastening holes (not shown) provided at both ends of each of the bars 8A and 8B. Note that the pressing member 8 may be formed by integrally combining a plurality of horizontal bars 8A and a plurality of vertical bars 8B in a lattice pattern by welding or the like, or may be integrally formed by casting or the like.

[0019] In the present embodiment, as will be described later, the cell stack 2 is indirectly pressed via a pressing bolt 15 (see FIG. 7), so there is a vertical gap between the pressing member 8 and the cell stack 2 while the pressing member 8 is fixed to the support portion 7. Note that the pressing member 8 may be configured to directly press the cell stack 2 without using the pressing bolt 15.

[0020] At the intersection of the horizontal crossbar 8A and the vertical crossbar 8B, a bolt hole 9 for inserting the pressing bolt 15 is provided. The nominal length of the pressing bolt 15 is larger than the thickness of the pressing member 8. The bolt hole 9 is provided with a thread, by which the protruding amount of the pressing bolt 15 from the lower surface of the pressing member 8 can be adjusted. That is, even if there are dimensional variations in the pressing member 8 and the cell stack 2, a desired pressure can be applied to the cell stack 2 by adjusting the protruding amount.

[0021] As described above, the fuel cell stack 1 according to the present embodiment has a configuration in which the cell stack 2 is pressed in the stacking direction by the pressing member 8 disposed inside the cover skirt 6. The effect of this configuration will be described with reference to FIG. 3.

[0022] Further, when a plurality of bolt holes 9 are arranged as described above, the pressing bolts 15 are arranged on a straight line connecting a pair of fastening holes 10 (that is, the fixing portions of the pressing member 8 and the cover skirt 6) facing each other with the cell stack 2 interposed therebetween.

[0023] FIG. 3 is a view in which a fixing portion (broken line portion in the figure) in the case of fixing the pressing member 8 outside the cover skirt 6 is superimposed on the top view of FIG. 2. As shown in the figure, when the fixing portion is provided outside, the horizontal dimension becomes L2×2 and the vertical dimension becomes L1×2, respectively, larger than the configuration of the present embodiment. That is, the configuration of the present embodiment can reduce the size of the fuel cell stack 1 compared to the configuration in which the fixing portion is provided outside.

[0024] Further, by providing the fixing portion inside, the distance between a pair of fixing portions facing each other with the cell stack interposed therebetween becomes shorter than the configuration in which the fixing portion is provided outside. That is, the length of the crossbar (beam length) across the fixing portions becomes shorter. Thereby, the amount of deformation of the crossbar can be suppressed. Specifically, it is as follows. Here, for the sake of simplicity, attention is paid to one crossbar, and the case where the crossbar is a simply supported beam and one pressing bolt 15 is provided at the center of the crossbar is considered. Since the pressing bolt 15 is on the straight line connecting a pair of fixing portions, the maximum deformation amount δ of the crossbar is expressed by Equation (1) using the formula for the case of a central concentrated load.

[0025]

Number

[0026] Here, F is the load applied to the beam, that is, the reaction force from the cell stack 2 input via the pressing bolt 15. L is the beam length. E is the longitudinal elastic modulus (Young's modulus). I is the second moment of area. b and h are the horizontal dimension and vertical dimension (thickness) of the beam, respectively.

[0027] If the beam length L becomes shorter, as is clear from Equation (1), the maximum deformation amount δ becomes smaller. Also, when the allowable maximum deformation amount δ is fixed, the horizontal and vertical dimensions of the beam can be reduced by the amount by which the beam length L is shortened.

[0028] That is, by adopting a configuration in which the pressing member 8 is fixed to the support portion 7 provided inside the cover skirt 6, not only can the entire fuel cell stack 1 be miniaturized, but also the thickness of the pressing member 8 can be reduced.

[0029] Next, the effect of fixing the pressing member 8 to the lower surface of the support portion 7 will be described.

[0030] A reaction force (force upward in the stacking direction) from the cell stack 2 is input to the pressing member 8 via the pressing bolt 15. At this time, in a configuration where the pressing member 8 is fixed to the upper surface of the support portion 7, only the axial force of the fastening bolt 16 resists the reaction force. On the other hand, in the configuration where the pressing member 8 is fixed to the lower surface of the support portion 7 as in the present embodiment, the support portion 7 holds down the pressing member 8 pushed up by the reaction force, so the load applied to the fastening bolt 16 can be reduced. That is, it becomes possible to reduce the diameter of the bolt used as the fastening bolt 16, and miniaturization and cost reduction can be achieved.

[0031] Also, above the pressing member 8, it is necessary to secure a space for the pressing bolt 15 that protrudes from the upper surface of the pressing member 8. However, if the pressing member 8 is fixed to the lower surface of the support portion 7, at least a space corresponding to the thickness of the support portion 7 is secured above the pressing member 8. Therefore, the space provided only for the pressing bolt 15 can be made smaller, and an increase in the size of the fuel cell stack 1 can be suppressed.

[0032] As described above, in this embodiment, a fuel cell stack 1 is provided that includes a cell stack 2 in which flat fuel cell cells are stacked in the thickness direction, a base plate 4 disposed at one end in the stacking direction of the cell stack 2, a cylindrical member having both ends open, one end of which is fixed to the base plate 4 and extends in the stacking direction from the base plate 4 and surrounds the cell stack 2, a cover skirt 6, a plurality of support portions 7 provided with a plurality of crossbars 8A, 8B and protruding from the inner wall of the cover skirt 6 in the inner direction of the cover skirt 6, and a pressing member 8 fixed to the plurality of support portions 7. The pressing member 8 directly or indirectly presses the cell stack 2 from the other end side in the stacking direction while being fixed to the support portion 7. According to this fuel cell stack 1, the outer dimensions of the fuel cell stack 1 can be reduced. Further, the beam length of the crossbars 8A, 8B can be made shorter compared to a configuration in which the support portion 7 is provided outside the cover skirt 6, so that it is easier to ensure the rigidity of the pressing member 8. And an increase in weight for ensuring large size and rigidity can also be suppressed.

[0033] In this embodiment, the pressing member 8 presses the cell stack 2 via a pressing bolt 15 that passes through bolt holes 9 provided in the crossbars 8A, 8B. Thereby, the load applied to the cell stack 2 can be adjusted.

[0034] In this embodiment, the pressing bolt 15 is disposed on a straight line connecting a pair of fixing portions that face each other with the cell stack 2 interposed therebetween among the fixing portions of the plurality of pressing members 8 and the cover skirt 6. Thereby, the amount of deformation of the pressing member 8 due to the reaction force from the cell stack 2 can be suppressed.

[0035] In this embodiment, the pressing member 8 is fixed on the same side as the cell stack 2 in the stacking direction of the support portion 7. As a result, the diameter of the fastening bolt 16 can be reduced. In addition, the space provided only for the fastening bolt 16 can be made smaller.

[0036] [Second Embodiment] FIG. 4 is a top view (with the lid omitted) of the fuel cell stack 1 according to the second embodiment of the present invention.

[0037] The difference between this embodiment and the first embodiment lies in the shape of the pressing member 8. Specifically, the pressing member 8 of this embodiment has a connection member 11 that connects the end portions adjacent to each other in the circumferential direction of the plurality of bars 8A and 8B, in addition to the same configuration as the pressing member 8 of the first embodiment. This configuration may also be integrally formed by welding or the like of the connection member 11 as a separate component, or integrally formed by casting or the like, as in the first embodiment.

[0038] Since the fuel cell stack 1 has an open cathode structure, the internal pressure of the cathode flow path formed in the cover skirt 6 increases when supplying cathode gas. It is desirable to suppress the deformation of the cover skirt 6 due to this internal pressure. Even with the pressing member 8 of the first embodiment, since both ends of the bars 8A and 8B are fixed to a pair of support portions 7 facing each other with the cell stack 2 interposed therebetween, the effect of suppressing the deformation of the cover skirt 6 due to the internal pressure can be obtained. On the other hand, since the pressing member 8 of this embodiment also connects the support portions 7 adjacent to each other in the circumferential direction, the effect of suppressing the deformation of the cover skirt 6 becomes greater.

[0039] Further, in the configuration where the connecting member 11 connects the support portions 7 adjacent to each other in the circumferential direction, the pressing bolt 15 is arranged on a straight line connecting a pair of fastening holes 10 facing each other with the cell stack 2 interposed therebetween among the plurality of fastening holes 10, whereby the amount of deformation of the pressing member 8 can be suppressed. This will be described with reference to FIGS. 5 to 7.

[0040] FIG. 5 is a top view of a pressing member (hereinafter also referred to as a comparative member 80) as a comparative example. In the comparative member 80, the ends of adjacent horizontal bars 80A and the ends of adjacent vertical bars 80B are connected by a connecting member 11, but the intersections of the horizontal bar 80A and the vertical bar 80B with the connecting member 11 are between adjacent fastening holes 10.

[0041] FIG. 6 is an enlarged view of a part of the comparative member 80, and FIG. 7 is an enlarged view of a part of the pressing member 8 according to the present embodiment.

[0042] A reaction force (upward force) from the cell laminate 2 is input to the horizontal bars 8A and 80A via the pressing bolts 15.

[0043] In the case of the comparative member 80, furthermore, the intersection of the horizontal bar 80A and the connecting member 11 is between adjacent fastening holes 10, and a reaction force (upward force) from the cell laminate 2 is input to this intersection via the horizontal bar 80A, causing the connecting member 11 to deform. That is, in the comparative member 80, since the support end of the horizontal bar 80A moves due to the deformation of the connecting member 11, not only the deformation amount of the horizontal bar 80A but also the deformation amount of the connecting member 11 causes the pressing bolt 15 to move, which may result in insufficient loading on the cell laminate 2.

[0044] On the other hand, in the case of the pressing member 8 of the present embodiment, since the intersection of the connecting member 11 and the horizontal bar 8A coincides with the fastening hole 10, the support end of the horizontal bar 8A does not move due to the deformation of the connecting member 11. Thus, since the deformation amount of the pressing member 8 is suppressed, insufficient loading on the cell laminate 2 can be suppressed.

[0045] As described above, in the present embodiment, the adjacent ends in the circumferential direction of the plurality of bars 8A and 8B are connected by the connecting member 11. Thereby, the deformation due to the internal pressure of the cover skirt 6 can be further suppressed.

[0046] Next, modified examples of the first and second embodiments will be described. The following modified examples are also within the scope of the present invention, and it is also possible to combine the following modified examples with the above-described embodiments or to combine the modified examples with each other.

[0047] [Modification Example 1] FIG. 8 is an enlarged cross-sectional view around the support portion 7 in the fuel cell stack 1 according to Modification Example 1.

[0048] In the support portion 7 in this modification example, a plurality of fastening holes 10 are provided, and the plurality of fastening holes 10 provided in the pair of support portions 7 facing each other with the cell laminate 2 interposed therebetween are arranged linearly. That is, as shown in FIG. 8, when two fastening holes 10 are provided in one support portion 7, the four fastening holes 10 provided in the pair of support portions 7 are arranged linearly.

[0049] With the above configuration, compared with the configuration in which one fastening hole 10 is provided in one support portion 7, the load applied to one fastening bolt 16 can be reduced. As a result, it is possible to further reduce the diameter of the fastening bolt 16 to be used.

[0050] [Modification Example 2] FIG. 9 is an enlarged cross-sectional view around the support portion 7 in the fuel cell stack 1 according to Modification Example 2.

[0051] In this modification example, the stacking direction dimension of the bars 8A and 8B of the pressing member 8 is larger the closer it is to the fixing portion (that is, the support portion 7) with the cover skirt 6. For example, as shown in FIG. 9, when the portions of the bars 8A and 8B that contact the side surface of the support portion 7 are used as the ends, the ends become the maximum thickness portions, and the boss portions that contact the lower surface of the support portion 7 protrude from the ends. Further, a rib 14 may be provided at the boundary portion between the maximum thickness portion and other portions.

[0052] As described above, a reaction force from the cell laminate 2 is input to the bars 8A and 8B via the pressing bolts 15. As a result, a bending moment is generated in the bars 8A and 8B, and the bending moment is larger in the portion closer to the support portion 7 which is the support end. Therefore, by providing the maximum thickness portion at the end as in this modification example, deformation of the bars 8A and 8B can be suppressed. In FIG. 9, a predetermined range from the end toward the center of the bar is the maximum thickness portion, but it is not limited to this. Depending on the distribution of the bending moment, the thickness may gradually decrease toward the center of the bar and be the minimum thickness at the center portion.

[0053] In addition, in the above-described embodiments and modified examples, the lattice-shaped pressing member 8 having the horizontal bars 8A and the vertical bars 8B has been described, but other shapes may also be used. For example, the horizontal bars 8A and the vertical bars 8B may be arranged in a ladder shape.

[0054] Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Explanation of Reference Numerals

[0055] 1 Fuel cell stack, 2 Cell laminate, 3 End plate, 4 Base plate, 5 Insulating member, 6 Cover skirt, 7 Support portion, 8 Pressing member

Claims

1. a cell stack in which flat fuel cell units are stacked in a thickness direction; A base plate arranged at one end of the cell stack in the stacking direction; A cover skirt is a cylindrical member having both ends open, one end of which is fixed to the base plate, the cover skirt extends from the base plate in the stacking direction, and surrounds the cell stack; A pressing member having a plurality of bars and fixed to a plurality of support portions protruding from an inner wall of the cover skirt toward the inside of the cover skirt; Equipped with a pressing member that presses the cell stack directly or indirectly from the other end side in the stacking direction while the cell stack is fixed to the support portion;

2. 2. The fuel cell stack according to claim 1, The pressing member presses the cell stack via a pressing bolt passing through a bolt hole provided in the crosspiece.

3. 3. The fuel cell stack according to claim 2, A fuel cell stack, wherein the pressing bolt is arranged on a straight line connecting a pair of fixing portions that face each other across the cell stack, among the multiple fixing portions between the pressing members and the cover skirt.

4. 4. The fuel cell stack according to claim 3, The pressing member and the cover skirt are fixed together by bolt fastening. A fuel cell stack, wherein each of the support portions is provided with a plurality of fastening bolt holes, and the plurality of fastening bolt holes provided in a pair of the support portions facing each other across the cell stack are arranged in a straight line.

5. 2. The fuel cell stack according to claim 1, a fuel cell stack, wherein the pressing member is fixed to the support portion on the same side as the cell stack in the stacking direction.

6. 2. The fuel cell stack according to claim 1, A fuel cell stack, wherein a dimension of the bar of the pressing member in a stacking direction is larger the closer it is to a portion where the bar is fixed to the cover skirt.

7. 2. The fuel cell stack according to claim 1, circumferentially adjacent ends of the plurality of crosspieces are connected to each other by a connecting member.

8. 2. The fuel cell stack according to claim 1, A fuel cell stack, wherein the cover skirt is an outer wall that constitutes an open cathode structure.

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