Fuel cell stack

Abstract

To provide a fuel cell stack capable of satisfying mounting requests different per user.SOLUTION: A fuel cell stack 1 includes a cell laminate 3 in which a plurality of fuel battery cells are laminated, and a case 2 accommodating the cell laminate 3. The cell laminate 3 includes a positive electrode terminal 31, a negative electrode terminal 32, a positive electrode bus bar 33, and a negative electrode bus bar 34. One end of the positive electrode bus bar 33 and one end of the negative electrode bus bar 34 are connected to the positive electrode terminal 31 and the negative electrode terminal 32, respectively, and the other end of the positive electrode bus bar and the other end of the negative electrode bus bar are pulled out to the center position of a corner consisting of an upper cover 22 and a first side wall 23 so as to be adjacent each other. The case 2 has an upper surface opening 26 in the upper cover 22 at the center position of the corner, and a side opening 25 in the first side wall 23 at the center position of the corner. The positive electrode bus bar 33 and the negative electrode bus bar 34 can be connected to outside the case through the upper surface opening 26 and the side opening 25.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as such a technical field, for example, there is one described in Patent Document 1. The fuel cell stack described in Patent Document 1 includes a cell stack in which a plurality of fuel cells are stacked, a first electrode terminal located at one end of the cell stack, a second electrode terminal located at the other end of the cell stack, a first connection terminal and a second connection terminal located at an end on the same side as the first electrode terminal, and a conductive member that conducts the second electrode terminal and the second connection terminal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When selling a fuel cell stack, different mounting requirements are demanded by users. For example, there are demands to mount the user-side connection destination unit above the fuel cell stack, and there are also demands to mount it on the side (for example, the left side or the right side) of the fuel cell stack. However, the above-described fuel cell stack has a problem that it cannot cope with such mounting requirements.

[0005] The present invention has been made to solve such technical problems, and an object thereof is to provide a fuel cell stack that can cope with different mounting requirements for each user. <0********>[[ID=************]]

Means for Solving the Problems

[0007] In the fuel cell stack according to the present invention, a first opening is provided in the top plate at the center of the corner, and a second opening is provided in the side wall at the center of the corner. This allows connection to the positive and negative busbars from outside the case via these openings. Therefore, the user's connection unit can be mounted from above and / or from the side of the fuel cell stack, thus accommodating different mounting requirements from each user.

[0008] In the fuel cell stack according to the present invention, it is preferable to provide restricting portions that are fixed to the other ends of the positive electrode busbar and the negative electrode busbar, and that face the corners of the cell stack to restrict the displacement of the cell stack. In this way, the rigidity of the positive electrode busbar and the negative electrode busbar can be used to restrict the displacement of the cell stack. [Effects of the Invention]

[0009] According to the present invention, it is possible to accommodate different installation requirements for each user. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the structure of a fuel cell stack according to an embodiment. [Figure 2] This is a plan view showing the fuel cell stack with the upper cover removed. [Figure 3] (a) is a plan view showing the positive busbar, negative busbar, and terminal block as seen from the top opening, and (b) is a plan view showing the positive busbar, negative busbar, and terminal block as seen from the side opening. [Figure 4] (a) is a schematic cross-sectional view showing mounting pattern 1 of the connected unit, and (b) is a schematic cross-sectional view showing mounting pattern 2 of the connected unit. [Figure 5] (a) is a schematic cross-sectional view showing mounting pattern 3 of the connected unit, and (b) is a schematic cross-sectional view showing mounting pattern 4 of the connected unit. [Figure 6] This is an enlarged schematic cross-sectional view showing the positional relationship between the terminal block and the corner of the cell stack. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the fuel cell stack according to the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. In the following description, the stacking direction of the fuel cell cells will be referred to as "stacking direction X", the gas flow direction within the fuel cell cells as "left-right direction Y", and the direction perpendicular to the stacking direction X and left-right direction Y as "up-down direction Z".

[0012] Figure 1 is a perspective view showing the structure of a fuel cell stack according to an embodiment, and Figure 2 is a plan view showing the fuel cell stack with the upper cover removed. Figure 3(a) is a plan view showing the positive electrode busbar, negative electrode busbar, and terminal block as seen from the top opening, and Figure 3(b) is a plan view showing the positive electrode busbar, negative electrode busbar, and terminal block as seen from the side opening. As shown in Figures 1 and 2, the fuel cell stack 1 of this embodiment comprises a box-shaped case 2 and a cell stack 3 housed inside the case 2.

[0013] The cell stack 3 is a cell stack formed by stacking multiple fuel cell cells in a certain direction, and constitutes a solid polymer electrolyte fuel cell. Although not shown in the figure, a fuel cell has a membrane / electrode assembly in which a polymer electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, and a pair of separators that sandwich the membrane / electrode assembly from both sides. The fuel cell generates electricity through an oxidation-reduction reaction between oxygen gas in the air supplied via the separator on the cathode electrode side and hydrogen gas supplied via the separator on the anode electrode side.

[0014] Case 2 is formed in the shape of a rectangular box from a metal material such as aluminum. This case 2 has a bottomed rectangular tubular case body 21 and an upper cover 22 that closes the opening of the case body 21. The upper cover 22 corresponds to the "top plate" described in the claims and is fixed to the case body 21 by bolts. The case body 21 consists of a bottom plate, a pair of first side walls 23 that extend along the stacking direction X and face each other, and a pair of second side walls 24 that extend along the left-right direction Y and face each other.

[0015] As shown in Figure 1, the top plate and side wall of case 2 are provided with a pair of adjacent openings. More specifically, the upper cover 22 has a top opening (first opening) 26 for exposing the other ends of the positive busbar 33 and negative busbar 34 (described later) and a part of the terminal block 4. The first side wall 23 has a side opening (second opening) 25 for exposing the other ends of the positive busbar 33 and negative busbar 34 and a part of the terminal block 4. The top opening 26 is formed in the center of the corner formed by the upper cover 22 and the first side wall 23. Correspondingly, the side opening 25 is formed in the center of the corner formed by the first side wall 23 and the upper cover 22. The top opening 26 is closed by the top cover member 28, and the side opening 25 is closed by the side cover member 27.

[0016] The upper opening 26 and the side opening 25 may be formed to have a common shape or may be formed to have different shapes. When they have a common shape, the processing operations for these openings can be made common, and the upper lid member 28 and the side lid member 27 for closing the openings can be made common, so that it is possible to reduce the component cost.

[0017] The cell stack 3 has a positive electrode terminal 31, a negative electrode terminal 32, a positive electrode bus bar 33, and a negative electrode bus bar 34. These terminals and bus bars are each formed in a plate shape from a metal material such as aluminum. The positive electrode terminal 31 and the negative electrode terminal 32 are arranged on both sides of the fuel cell stack direction X so as to face each other. That is, the positive electrode terminal 31 is arranged near one of the pair of opposing second side walls 24, and the negative electrode terminal 32 is arranged near the other of the pair of opposing second side walls 24.

[0018] One end of each of the positive electrode bus bar 33 and the negative electrode bus bar 34 is connected to the positive electrode terminal 31 or the negative electrode terminal 32, and the other end is drawn out to the central position of the corner formed by the upper cover 22 and the first side wall 23 of the case 2 so as to be adjacent to each other. And a terminal block 4 is arranged near the central position of the corner formed by the upper cover 22 and the first side wall 23. The other ends of the positive electrode bus bar 33 and the negative electrode bus bar 34 are fixed to the terminal block 4.

[0019] Specifically, the positive electrode bus bar 33 is spanned between the positive electrode terminal 31 and the terminal block 4 so as to electrically connect the positive electrode terminal 31 and the terminal block 4. As shown in FIGS. 2 and 3, the positive electrode bus bar 33 has a flat plate portion 331 arranged in parallel with the upper cover 22 and having a curved shape, and an L-shaped portion 332 having a portion parallel to the upper cover 22 and a portion parallel to the first side wall 23. One end portion of the flat plate portion 331 is fixed to the positive electrode terminal 31 by bolt tightening, and the other end portion is fixed to the L-shaped portion 332 and the terminal block 4 via a bolt 100. On the other hand, for the L-shaped portion 332, the portion parallel to the upper cover 22 is fixed to the other end portion of the flat plate portion 331 and the terminal block 4 via a bolt 100, and the portion parallel to the first side wall 23 is fixed to the terminal block 4 via a bolt 101.

[0020] The negative electrode bus bar 34 is spanned between the negative electrode terminal 32 and the terminal block 4 so as to electrically connect the negative electrode terminal 32 and the terminal block 4. As shown in FIGS. 2 and 3, the negative electrode bus bar 34 has a flat plate portion 341 arranged in parallel with the upper cover 22 and having a curved shape, and an L-shaped portion 342 having a portion parallel to the upper cover 22 and a portion parallel to the first side wall 23. One end portion of the flat plate portion 341 is fixed to the negative electrode terminal 32 by bolt tightening, and the other end portion is fixed to the L-shaped portion 342 and the terminal block 4 via a bolt 102. On the other hand, for the L-shaped portion 342, the portion parallel to the upper cover 22 is fixed to the other end portion of the flat plate portion 341 and the terminal block 4 via a bolt 102, and the portion parallel to the first side wall 23 is fixed to the terminal block 4 via a bolt 103.

[0021] Note that the positive electrode bus bar 33 and the negative electrode bus bar 34 do not necessarily need to be formed to have the flat plate portions 331, 341 and the L-shaped portions 332, 342. For example, the flat plate portion 331 and the L-shaped portion 332 may be integrally formed by a single plate member.

[0022] The terminal block 4 is formed of a metal material such as aluminum and is fixed to the case 2 in a state of being electrically insulated from the case 2.

[0023] In this embodiment, the positive electrode terminals 31 and negative electrode terminals 32, which are located at both ends of the stacking direction X of the cell stack 3, are consolidated by the positive electrode busbar 33 and the negative electrode busbar 34 into a terminal block 4 located near the center of the corner formed by the upper cover 22 and the first side wall 23. Therefore, when assembling the user-side connection unit to the fuel cell stack 1, the opening required for connection (i.e., the side opening 25 or the top opening 26) can be made smaller. For this reason, compared to, for example, the case where the busbars are located at both ends of the stacking direction X of the cell stack 3, the shape of the connection unit does not need to extend to both ends of the stacking direction X, so the connection unit can be made smaller.

[0024] Furthermore, since the upper cover 22 has an upper opening 26 for exposing the other ends of the positive electrode busbar 33 and the negative electrode busbar 34, it becomes possible to connect to the positive electrode busbar 33 and the negative electrode busbar 34 from outside the case 2 via the upper opening 26. This allows the user's connection unit to be mounted above the case 2 (in other words, above the fuel cell stack 1).

[0025] Furthermore, the first side wall 23 has a side opening 25 for exposing the other ends of the positive electrode busbar 33 and the negative electrode busbar 34, so that the positive electrode busbar 33 and the negative electrode busbar 34 can be connected to each other from outside the case 2 via the side opening 25. This allows the user's connection unit to be mounted on the side of the case 2 (in other words, on the side of the fuel cell stack 1).

[0026] In this way, the user's destination unit can be mounted from above and / or the side of Case 2, thus accommodating different mounting requirements for each user. As a result, the robustness of mounting the destination unit can be improved.

[0027] The following describes a pattern in which the destination unit is mounted on the fuel cell stack 1, based on Figures 4 and 5.

[0028] [Mounting Pattern 1] Mounting pattern 1 shown in Figure 4(a) is a pattern in which the destination unit 5 is mounted on the side of the fuel cell stack 1. In this pattern, the connecting busbar 51 provided on the destination unit 5 is inserted through the side opening 25 of the case 2 and is fixed to the positive electrode busbar 33 or negative electrode busbar 34 via bolts 100 and 102 while resting on the upper surface of the flat plate portions 331 and 341 of the positive electrode busbar 33 or negative electrode busbar 34. The connecting busbar 51 is made of a straight metal plate.

[0029] When mounting the destination unit 5 to the side of the fuel cell stack 1 in this manner, first, the side cover member 27 and the top cover member 28 of the fuel cell stack 1 are removed to expose the other ends of the positive electrode busbar 33 and the negative electrode busbar 34. Next, the destination unit 5 is assembled to the fuel cell stack 1 from the side of the case 2 so that the connecting busbar 51 is inserted into the inside of the case 2 through the side opening 25. Then, a fastening tool is inserted through the top opening 26 of the case 2, and the connecting busbar 51 is fastened to the flat plate portions 331 and 341 of the positive electrode busbar 33 or the negative electrode busbar 34 with bolts 100 and 102. After fastening, the top opening 26 of the case 2 is closed with the top cover member 28.

[0030] In mounting pattern 1, the destination unit 5 is assembled to the fuel cell stack 1 from the side of the case 2, and the connecting busbar 51 is fastened to the positive electrode busbar 33 or negative electrode busbar 34 of the fuel cell stack 1 from above the case 2 using a fastening tool, thus making the mounting work of the destination unit 5 easy. In addition, since there is no need for a service hole in the destination unit 5 for inserting the fastening tool, costs can be reduced compared to when a service hole is provided in the destination unit 5.

[0031] [Mounting Pattern 2] Mounting pattern 2 shown in Figure 4(b) is a pattern in which the destination unit 5 is mounted on the side of the fuel cell stack 1. In this pattern, the connecting busbar 52 provided on the destination unit 5 is inserted through the side opening 25 of the case 2 and is fixed to the positive electrode busbar 33 or negative electrode busbar 34 via bolts 101 and 103 while in contact with the L-shaped portions 332 and 342 of the positive electrode busbar 33 or negative electrode busbar 34. The connecting busbar 52 is made of a metal plate with an L-shaped cross-section, having a portion 521 that extends along the left-right direction Y and a portion 522 that extends along the up-down direction Z. The portion 522 that extends along the up-down direction Z is sized to pass through the side opening 25 of the case 2.

[0032] When mounting the destination unit 5 to the side of the fuel cell stack 1 in this manner, first, the side cover member 27 of the fuel cell stack 1 is removed to expose the other ends of the positive electrode busbar 33 and the negative electrode busbar 34. Next, the destination unit 5 is assembled to the fuel cell stack 1 from the side of the case 2 so that the connecting busbar 52 is inserted into the inside of the case 2 through the side opening 25. Subsequently, a fastening tool is inserted into the service hole 53 formed in the destination unit 5, and bolts 101 and 103 are used to fasten the portion 522 of the connecting busbar 52 to the L-shaped portions 332 and 342 of the positive electrode busbar 33 or the negative electrode busbar 34.

[0033] In mounting pattern 2, the connection unit 5 is assembled to the fuel cell stack 1 from the side of case 2, and the connection busbar 52 is fastened to the positive busbar 33 or negative busbar 34 using the service hole 53 of the connection unit 5 from the side of case 2, so no work from above case 2 is required. Therefore, other components 6 may be placed above the top opening 26.

[0034] [Installation Pattern 3] Mounting pattern 3 shown in Figure 5(a) is a pattern in which the destination unit 5 is mounted on top of the fuel cell stack 1. In this pattern, the connecting busbar 54 provided on the destination unit 5 is inserted through the top opening 26 of the case 2 and is fixed to the positive or negative busbar 33 or negative busbar 34 via bolts 101 and 103 while overlapping with the L-shaped portions 332 and 342 of the positive or negative busbar 33 or negative busbar 34. The connecting busbar 54 is made of a straight metal plate.

[0035] When mounting the destination unit 5 on top of the fuel cell stack 1 in this manner, first, the side cover member 27 and the top cover member 28 of the fuel cell stack 1 are removed to expose the other ends of the positive electrode busbar 33 and the negative electrode busbar 34. Next, the destination unit 5 is assembled to the fuel cell stack 1 from above the case 2 so that the connecting busbar 54 is inserted into the inside of the case 2 through the top opening 26. Then, a fastening tool is inserted through the side opening 25 of the case 2, and the connecting busbar 54 and the L-shaped portions 332 and 342 of the positive electrode busbar 33 or negative electrode busbar 34 are fastened with bolts 101 and 103. After fastening, the side opening 25 of the case 2 is closed with the side cover member 27.

[0036] In mounting pattern 3, the destination unit 5 is assembled onto the fuel cell stack 1 from above the case 2, and the connecting busbar 54 is fastened to the positive or negative busbar 33 of the fuel cell stack 1 using a fastening tool from the side of the case 2, making the mounting of the destination unit 5 easy. In addition, since there is no need for a service hole in the destination unit 5 for inserting the fastening tool, costs can be reduced compared to cases where a service hole is provided in the destination unit 5.

[0037] [Mounting Pattern 4] The mounting pattern 4 shown in Figure 5(b) is a pattern in which the destination unit 5 is mounted above the fuel cell stack 1. In this pattern, the connecting busbar 55 provided on the destination unit 5 is inserted through the top opening 26 of the case 2 and is fixed to the positive electrode busbar 33 or negative electrode busbar 34 via bolts 100 and 102 while in contact with the flat plate portions 331 and 341 of the positive electrode busbar 33 or negative electrode busbar 34. The connecting busbar 55 is made of a metal plate with an L-shaped cross-section, having a portion 551 that extends along the vertical direction Z and a portion 552 that extends along the left-right direction Y. The portion 552 that extends along the left-right direction Y is sized to pass through the top opening 26 of the case 2.

[0038] When mounting the destination unit 5 on top of the fuel cell stack 1 in this manner, first, the top cover member 28 of the fuel cell stack 1 is removed to expose the other ends of the positive electrode busbar 33 and the negative electrode busbar 34. Next, the destination unit 5 is assembled to the fuel cell stack 1 from above the case 2 so that the connecting busbar 55 is inserted into the inside of the case 2 through the top opening 26. Subsequently, a fastening tool is inserted into the service hole 56 formed in the destination unit 5, and bolts 100 and 102 are used to fasten the portion 552 of the connecting busbar 55 that extends along the left-right direction Y to the flat plate portions 331 and 341 of the positive electrode busbar 33 or the negative electrode busbar 34.

[0039] In mounting pattern 4, the connection unit 5 is assembled to the fuel cell stack 1 from above the case 2, and the connection busbar 55 is fastened to the positive electrode busbar 33 or negative electrode busbar 34 using the service hole 56 of the connection unit 5 from above the case 2, so no work from the side of the case 2 is required. Therefore, other components 6 may be placed to the side of the side opening 25.

[0040] Furthermore, the terminal block 4 in this embodiment serves as a restricting unit that restricts the displacement of the cell stack 3. This will be explained below with reference to Figure 6.

[0041] Specifically, as shown in Figure 6, the terminal block 4 has an L-shaped cross-section so as to align with the corner 35 of the adjacent cell stack 3. The terminal block 4 has a first portion 40 extending along the left-right direction Y and a second portion 41 extending along the up-down direction Z.

[0042] Here, we will explain the reason why terminal block 4 has an L-shaped cross-section.

[0043] In Case 2, both ends of the cell stack 3 in the stacking direction X are fixed to Case 2, but the portion between the ends is not fixed to Case 2 and is in a floating state. Therefore, when an external force is applied to the fuel cell stack 1, the portion of the cell stack 3 between the ends in the stacking direction X moves (i.e., displaces). The central portion of the cell stack 3 between the ends in the stacking direction X is displaced the most. Recently, increasing the number of stacked fuel cell cells has been considered in order to increase the output of the fuel cell stack. However, increasing the number of stacked fuel cell cells increases the mass of the cell stack 3, and the amount of displacement of the cell stack 3 when an external force is applied also increases. If the allowable displacement between adjacent fuel cell cells is exceeded, seal failures occur, leading to problems such as water leakage and hydrogen leakage.

[0044] To solve these problems, the inventors of the present invention conducted extensive research and found that by placing the terminal block 4 at a position in the case 2 corresponding to the central part of the cell stack 3 in the stacking direction X, which is displaced the most by external forces (more specifically, near the central position of the corner formed by the upper cover 22 and the first side wall 23), and by making the terminal block 4 L-shaped with parts corresponding to the top surface and side surface of the cell stack 3, the displacement of the cell stack 3 in the left-right direction Y and the up-down direction Z can be suppressed (in other words, restricted) by the terminal block 4, thereby limiting the amount of displacement of the cell stack 3 to below an allowable value.

[0045] Therefore, as shown in Figure 6, the terminal block 4 is positioned so that the inside of its L-shaped corner faces the corner 35 of the cell stack 3, so as to align with the corner 35 of the cell stack 3. For example, if the cell stack 3 is displaced in the vertical direction Z by an external force, the displacement in the vertical direction Z can be suppressed by interfering with the first part 40 of the terminal block 4. Also, if the cell stack 3 is displaced in the horizontal direction Y by an external force, the displacement in the horizontal direction Y can be suppressed by interfering with the second part 41 of the terminal block 4.

[0046] Furthermore, since the terminal block 4 is fixed to the case 2 and connected to both ends of the cell stack 3 in the stacking direction X via the positive busbar 33 and the negative busbar 34, and is fixed to both ends of the cell stack 3 in the stacking direction X, the rigidity of the busbars can be utilized to increase the resistance of the terminal block 4 to displacement. Consequently, the terminal block 4 can suppress the displacement of the cell stack 3 and keep the amount of displacement of the fuel cell cells below the allowable value.

[0047] Furthermore, by positioning the terminal block 4 at the location of case 2 corresponding to the central part of the stacking direction X of the cell stack 3 where the displacement is greatest (more specifically, near the central position of the corner formed by the upper cover 22 and the first side wall 23), the amount of displacement of the cell stack 3 can be suppressed most efficiently. And, if the width at which the displacement of the cell stack 3 peaks is equal to or greater than the width that the terminal block 4 can suppress (in other words, if the width of the terminal block 4 is greater than the width of the displacement peak), the terminal block 4 can suppress the area of ​​the cell stack 3 that needs to be suppressed.

[0048] Furthermore, since the terminal block 4 also serves as a restricting element that controls the displacement of the cell stack 3, there is no need to place a dedicated component to restrict displacement, which also has the effect of suppressing cost increases.

[0049] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of symbols]

[0050] 1: Fuel cell stack, 2: Case, 3: Cell stack, 4: Terminal block, 5: Connection unit, 21: Case body, 22: Upper cover, 23: First side wall, 24: Second side wall, 25: Side opening, 26: Top opening, 27: Side cover member, 28: Top cover member, 31: Positive terminal, 32: Negative terminal, 33: Positive busbar, 34: Negative busbar, 35: Corner section, 40: First section, 41: Second section, 51, 52, 54, 55: Connecting busbars, 331, 341: Flat section, 332, 342: L-shaped section

Claims

1. A fuel cell stack comprising a cell stack formed by stacking multiple fuel cell cells, and a case for housing the cell stack, The cell laminate has a positive terminal, a negative terminal, a positive busbar, and a negative busbar. The positive and negative busbars are connected at one end to the positive or negative terminal, and their other ends are drawn out to the center of the corner formed by the top plate and side wall of the case, so as to be adjacent to each other. The case has a first opening in the top plate at the center of the corner, and a second opening in the side wall at the center of the corner. A fuel cell stack characterized in that each of the positive electrode busbar and the negative electrode busbar is connected to the outside of the case via a bolt formed at a position corresponding to the first opening or a bolt formed at a position corresponding to the second opening.

2. The fuel cell stack according to claim 1, further comprising restricting portions fixed to the other ends of the positive electrode busbar and the negative electrode busbar, and facing the corners of the cell stack, for restricting the displacement of the cell stack.

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