Fuel cell unit and its assembly method

Abstract

To achieve both flexibility and ease of assembly of a busbar that electrically connects a fuel cell stack and an electrical device in a fuel cell unit.SOLUTION: A fuel cell unit includes a fuel cell stack in which a plurality of fuel cells are stacked, an electrical device, and a busbar that electrically connects the terminal of the fuel cell stack and the terminal of the electrical device. The busbar includes a non-bonded portion in which a plurality of metal plates are stacked without being bonded to each other. The plurality of metal plates include a first metal plate and a second metal plate that is thicker than the first metal plate.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a fuel cell unit including a bus bar and a method for assembling the same.

Background Art

[0002] Patent Document 1 discloses a fuel cell unit. The fuel cell unit has a fuel cell stack including a cell stack in which a plurality of fuel cell cells are stacked. The fuel cell unit further has an electrical device electrically connected to the fuel cell stack. A bus bar is provided to electrically connect between a terminal of the fuel cell stack and a terminal of the electrical device. The size of the cell stack in the stacking direction changes according to the environment. In conjunction with the change in the size of the cell stack, the position of the terminal of the fuel cell stack also changes. The bus bar has a U-shaped bent portion (following portion) so that it can deform following the displacement of the terminal of the fuel cell stack.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Consider a bus bar that electrically connects between a terminal of a fuel cell stack and a terminal of an electrical device in a fuel cell unit. The cell stack included in the fuel cell stack expands / contracts in the stacking direction according to the environment. In conjunction with such expansion / contraction of the cell stack, the position of the terminal of the fuel cell stack also changes. Also, due to manufacturing variations, etc., there may be variations in the relative positional relationship between the terminal of the fuel cell stack and the terminal of the electrical device. In order to absorb such environment-dependent displacement and relative position variations, it is desirable for the bus bar to have "flexibility".

[0005] On the other hand, if the busbar is excessively flexible, it becomes difficult to smoothly assemble it between the terminals of the fuel cell stack and the terminals of the electrical equipment. In other words, the "assemblability" of the busbar decreases.

[0006] One objective of this disclosure is to provide a technology that can achieve both flexibility and ease of assembly for busbars that electrically connect fuel cell stacks and electrical equipment in fuel cell units. [Means for solving the problem]

[0007] The first point concerns the fuel cell unit. The fuel cell unit is A fuel cell stack consisting of multiple fuel cell cells stacked on top of each other, Electrical equipment and, A busbar that electrically connects the terminals of the fuel cell stack and the terminals of the electrical equipment. It is equipped with. A busbar includes a non-jointed section in which multiple metal plates are stacked without being joined to each other. The multiple metal plates include a first metal plate and a second metal plate that is thicker than the first metal plate.

[0008] From the first perspective, the busbar includes a non-jointed section where multiple metal plates are laminated without being joined to each other. Therefore, the flexibility of the non-jointed section is significantly higher compared to the case where multiple metal plates are joined to form a single thick metal plate. The high flexibility of the non-jointed section means that it is easily deformable. Because the non-jointed section is easily deformable, it can easily absorb environmentally dependent displacement of the terminals and variations in the relative positional relationship between the terminals. In addition, because multiple metal plates are laminated, a sufficient cross-sectional area is secured for the non-jointed section as a whole, preventing an increase in resistance. Furthermore, the multiple metal plates of the non-jointed section include a first metal plate and a second metal plate that is thicker than the first metal plate. The relatively thick second metal plate has higher rigidity than the first metal plate and is less likely to bend due to gravity. Therefore, the second metal plate contributes to maintaining the posture (shape) of the busbar (non-jointed section) during assembly. In other words, the second metal plate improves the ease of assembly of the busbar. Thus, from the first perspective, it is possible to ensure "low resistance," "flexibility," and "ease of assembly" with respect to the busbar.

[0009] The second perspective, in addition to the first perspective, has the following further characteristics: The non-jointed section includes a bent section formed by bending multiple metal plates.

[0010] From a second perspective, because the non-joint portion includes a bent portion, it becomes easier to deform the non-joint portion in two dimensions. Therefore, it becomes possible to easily absorb various environment-dependent displacements of the terminals. Furthermore, it becomes possible to easily absorb various variations in the relative positional relationship between terminals.

[0011] The third perspective has the following additional characteristics in addition to those of the first or second perspective: The number of second metal plates is less than the number of first metal plates. The number of second metal plates may be 1.

[0012] From a third perspective, it becomes possible to efficiently ensure low resistance, flexibility, and ease of assembly with respect to the busbar without unnecessarily reducing flexibility.

[0013] The fourth perspective has the following additional characteristics in any of the first to third perspectives: The number of first metal plates is two or more. The second metal plate is sandwiched between two or more first metal plates. The second metal plate has a first surface and a second surface opposite to the first surface. The number of first metal plates on the first surface side of the second metal plate may be equal to the number of first metal plates on the second surface side of the second metal plate.

[0014] From a fourth perspective, the first metal plate can be deformed more freely without being constrained by the second metal plate. Therefore, the flexibility of the non-jointed portion is further improved.

[0015] The fifth perspective has the following additional characteristics in any of the first to third perspectives: Of the multiple metal plates, the second metal plate is positioned at the bottom in the direction of gravity.

[0016] From the fifth perspective, a second metal plate is located below the first metal plate, and the first metal plate is supported by the second metal plate. Therefore, deflection of the first metal plate due to gravity is prevented. As a result, the first metal plate is prevented from deflecting and coming into contact with other components such as electrical equipment.

[0017] The sixth perspective has the following additional characteristics in any of the first to third perspectives: Of the multiple metal plates, the second metal plate is positioned at the top in the direction of gravity.

[0018] From the sixth perspective, the first metal plate is less likely to form bundles because it is easily dispersed in the direction of gravity. This is desirable from the viewpoint of flexibility of the non-jointed parts.

[0019] The seventh perspective has the following additional characteristics in any of the first to third perspectives: The busbar further includes a first connection portion that connects to the terminals of the fuel cell stack and a second connection portion that connects to the terminals of the electrical equipment. The non-jointed portion is located between the first joint and the second joint.

[0020] The eighth aspect further has the following features in addition to the seventh aspect. The non-joint part includes bent parts where a plurality of metal plates are bent. At the bent part closest to the second connection part, the second metal plate among the plurality of metal plates is located on the outermost side. In the non-joint part, the second metal plate may be longer than the first metal plate.

[0021] According to the eighth aspect, it becomes possible to effectively suppress the maximum stress value of the entire bus bar.

[0022] The ninth aspect further has the following features in addition to the seventh aspect. In each of the first connection part and the second connection part, the plurality of metal plates are joined to each other.

[0023] According to the ninth aspect, the rigidity of the first connection part and the second connection part of the bus bar is increased, and the connection to the terminal becomes easier.

[0024] The tenth aspect relates to a method of assembling a fuel cell unit. The fuel cell unit includes a fuel cell stack in which a plurality of fuel cell cells are stacked and an electrical device. The assembling method includes a step of forming a bus bar in which a plurality of metal plates including a first metal plate and a second metal plate thicker than the first metal plate are stacked, a step of electrically connecting the first connection part of the bus bar to the terminal of the fuel cell stack, a step of electrically connecting the second connection part of the bus bar to the terminal of the electrical device and includes. The step of forming the bus bar includes joining the plurality of metal plates to each other at each of the first connection part and the second connection part without joining the plurality of metal plates to each other at the non-joint part between the first connection part and the second connection part.

[0025] According to the tenth aspect, the same effects as the above-mentioned first aspect and ninth aspect can be obtained. [Effects of the Invention]

[0026] According to this disclosure, it is possible to ensure "low resistance," "flexibility," and "ease of assembly" with respect to the busbars of the fuel cell unit. [Brief explanation of the drawing]

[0027] [Figure 1] This is a schematic diagram showing an example of the configuration of a fuel cell unit according to an embodiment of the present disclosure. [Figure 2] This is a schematic diagram illustrating an example of the electrical connection of a busbar in a fuel cell unit according to an embodiment of the present disclosure. [Figure 3] This is a diagram illustrating the assembly method of a fuel cell unit according to an embodiment of the present disclosure. [Figure 4] This is a diagram illustrating the assembly method of a fuel cell unit according to an embodiment of the present disclosure. [Figure 5] This is a diagram illustrating the assembly method of a fuel cell unit according to an embodiment of the present disclosure. [Figure 6] This is a diagram illustrating the assembly method of a fuel cell unit according to an embodiment of the present disclosure. [Figure 7] This is a diagram illustrating the assembly method of a fuel cell unit according to an embodiment of the present disclosure. [Figure 8] This is a schematic diagram illustrating an example of a busbar using multiple metal plates according to an embodiment of the present disclosure. [Figure 9] This is a conceptual diagram to explain the problem. [Figure 10] This is a schematic diagram illustrating another example of a busbar using multiple metal plates according to an embodiment of the present disclosure. [Figure 11] This is a schematic diagram showing a first example of a busbar according to an embodiment of the present disclosure. [Figure 12] This is a schematic diagram showing a second example of a busbar according to an embodiment of the present disclosure. [Figure 13]This is a schematic diagram showing a third example of a busbar according to an embodiment of the present disclosure. [Figure 14] This is a schematic diagram showing a fourth example of a busbar according to an embodiment of the present disclosure. [Figure 15] This is a schematic diagram showing a fifth example of a busbar according to an embodiment of the present disclosure. [Figure 16] This is a schematic diagram showing a sixth example of a busbar according to an embodiment of the present disclosure. [Figure 17] This is a conceptual diagram illustrating the effects of a sixth example of a busbar according to an embodiment of the present disclosure. [Figure 18] This is a schematic diagram showing a seventh example of a busbar according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0028] Embodiments of this disclosure will be described with reference to the attached drawings.

[0029] 1. Overall configuration of the fuel cell unit Figure 1 is a schematic diagram showing an example of the configuration of a fuel cell unit 1 according to this embodiment. The fuel cell unit 1 includes a fuel cell stack 10 and an electrical equipment unit 100. The fuel cell stack 10 and the electrical equipment unit 100 are combined integrally to constitute the fuel cell unit 1.

[0030] The fuel cell stack 10 includes a cell stack 12 in which multiple fuel cell cells 11 are stacked in series. Each fuel cell cell 11 includes an electrolyte membrane and cathode and anode electrodes on both sides of the electrolyte membrane. In the following description, the S direction represents the stacking direction of the multiple fuel cell cells 11. The T direction represents the direction parallel to each fuel cell cell 11. The S direction and the T direction are orthogonal.

[0031] The fuel cell stack 10 further includes a first battery terminal 21 and a second battery terminal 22. The first battery terminal 21 and the second battery terminal 22 are connected to both ends of the cell stack 12 in the S direction. For example, each of the first battery terminal 21 and the second battery terminal 22 has a plate shape. Copper is an example of a material for the first battery terminal 21 and the second battery terminal 22.

[0032] The stack case 30 is the case for the fuel cell stack 10. The stack case 30 consists of end plates 31 and 32 and connecting parts 33 and 34 that connect the end plates 31 and 32. Examples of materials for the stack case 30 include stainless steel and aluminum alloy. The cell stack 12 is housed inside the stack case 30. An insulator 41, a pressure plate 50, and a spring 60 are placed between the first battery terminal 21 and the end plate 31. An insulator 42 is placed between the second battery terminal 22 and the end plate 32. Due to the reaction force of the spring 60, a compressive load in the S direction is applied to the cell stack 12. Since the compressive load on the cell stack 12 can be maintained within a certain range, it becomes easier to maintain power generation performance and sealing performance.

[0033] One end of each of the first battery terminal 21 and the second battery terminal 22 protrudes outside the cell stack 12 and extends toward the electrical equipment section 100.

[0034] The electrical equipment section 100 includes electrical equipment 110, a first terminal block 121, a second terminal block 122, and a case 130.

[0035] The electrical device 110 is electrically connected to the fuel cell stack 10. For example, the electrical device 110 is a boost converter that increases the output voltage of the fuel cell stack 10. As another example, the electrical device 110 may be a buck converter that decreases the output voltage of the fuel cell stack 10. The electrical device 110 may also be a buck-boost converter. As yet another example, the electrical device 110 may be an inverter that converts the DC output from the fuel cell stack 10 to AC. Otherwise, the electrical device 110 can be anything as long as it is electrically connected to the fuel cell stack 10.

[0036] The first terminal block 121 and the second terminal block 122 are terminals for the electrical equipment 110.

[0037] The electrical equipment 110, the first terminal block 121, and the second terminal block 122 are housed in the case 130.

[0038] In a state where the fuel cell stack 10 and the electrical equipment unit 100 are integrated, the electrical equipment 110 is spaced apart from the fuel cell stack 10. In the example shown in Figure 1, the fuel cell stack 10 and the electrical equipment 110 are spaced apart in the T direction. A busbar is used to electrically connect the fuel cell stack 10 and the electrical equipment 110 in such a configuration.

[0039] More specifically, the fuel cell unit 1 includes a first busbar 210 and a second busbar 220. The first busbar 210 electrically connects the first battery terminal 21 of the fuel cell stack 10 to the first terminal block 121 of the electrical equipment 110. The second busbar 220 electrically connects the second battery terminal 22 of the fuel cell stack 10 to the second terminal block 122 of the electrical equipment 110. Typically, each of the first busbar 210 and the second busbar 220 has a plate shape. Examples of materials for the first busbar 210 and the second busbar 220 include copper, aluminum, alloys containing a large amount of copper or aluminum, etc.

[0040] Figure 2 is a schematic diagram illustrating an example of the electrical connection of the first busbar 210 in the fuel cell unit 1. The first busbar 210 includes a first connection part 210A connected to the first battery terminal 21 and a second connection part 210B connected to the first terminal block 121. The first connection part 210A and the second connection part 210B are located apart from each other on the first busbar 210. For example, the first connection part 210A and the second connection part 210B are located at both ends of the first busbar 210. The first connection part 210A is fixed to the first battery terminal 21. On the other hand, the second connection part 210B is fixed to the first terminal block 121.

[0041] In the example shown in Figure 2, the tip 21A of the first battery terminal 21 is bent. The tip 21A of the first battery terminal 21 is parallel to the S direction and intersects with the T direction. The first connection portion 210A of the first busbar 210 is also parallel to the S direction and intersects with the T direction. A nut 25 is attached to the tip 21A of the first battery terminal 21. The tip 21A of the first battery terminal 21 and the first connection portion 210A of the first busbar 210 are fastened together with a bolt 300.

[0042] On the other hand, the first terminal block 121 is parallel to the T direction and intersects with the S direction. The second connection portion 210B of the first bus bar 210 is also parallel to the T direction and intersects with the S direction. A nut 125 is attached to the first terminal block 121. The first terminal block 121 and the second connection portion 210B of the first bus bar 210 are fastened together by a bolt 400.

[0043] In the example shown in Figure 2, a plane parallel to the first connection portion 210A intersects with a plane parallel to the second connection portion 210B. In this case, the first busbar 210 has at least one bend between the first connection portion 210A and the second connection portion 210B. The number of bends is not particularly limited. The curvature of the bends is also not particularly limited. The portion between the first connection portion 210A and the second connection portion 210B may be bent into a large arc shape.

[0044] The second busbar 220 is the same as the first busbar 210.

[0045] 2. How to assemble the fuel cell unit Figures 3 to 7 are diagrams illustrating the assembly method of the fuel cell unit 1 shown in Figures 1 and 2. In Figures 3 to 7, the direction of gravity is indicated by an arrow.

[0046] First, the fuel cell stack 10 is prepared. As described above, one end of the first battery terminal 21 and the second battery terminal 22 of the fuel cell stack 10 protrudes outside the cell stack 12. As shown in Figure 3, the fuel cell stack 10 is placed so that the protruding first battery terminal 21 and second battery terminal 22 are visible from above. Note that the tips of the protruding first battery terminal 21 and second battery terminal 22 are bent (see Figure 2), so the height of the protruding parts is kept low.

[0047] Next, as shown in Figure 4, the pre-formed first busbar 210 is fastened to the first battery terminal 21 from above with a bolt 300 (see Figure 2). At this time, since the tip of the first battery terminal 21 is bent, it is easy to fasten the first busbar 210 to the first battery terminal 22 from above with the bolt 300. Similarly, the pre-formed second busbar 220 is fastened to the second battery terminal 22 from above with a bolt 300. The detailed structure of the busbars according to this embodiment and the method of forming them will be described in detail later.

[0048] Next, as shown in Figure 5, the electrical equipment unit 100 is placed on top of the fuel cell stack 10. At this time, the bottom of the electrical equipment unit 100 is open. The stack case 30 of the fuel cell stack 10 and the case 130 of the electrical equipment unit 100 are fastened together with bolts (not shown). An opening 131 is provided on the side of the case 130 of the electrical equipment unit 100.

[0049] Next, as shown in Figure 6, a bolt 400 is inserted through the opening 131 on the side of the case 130. The first busbar 210 is then fastened to the first terminal block 121 from the side by the bolt 400 (see Figure 2). Similarly, the second busbar 220 is fastened to the second terminal block 122 from the side by the bolt 400.

[0050] Finally, as shown in Figure 7, the opening 131 on the side of the case 130 is covered.

[0051] 3. Characteristics of the bus bar The cell stack 12 contained in the fuel cell stack 10 expands and contracts in the S direction (stack direction) depending on the environment. For example, the cell stack 12 expands at high temperatures and contracts at low temperatures. As another example, when the relative humidity inside the fuel cell cell 11 is high, the electrolyte membrane inside the fuel cell cell 11 absorbs water and expands. As yet another example, if a compressive load is applied to the cell stack 12 for a long period of time, the resin component creeps slightly, causing the cell stack 12 to contract.

[0052] When the cell stack 12 expands / contracts in the S direction, the terminal positions change in the S direction in conjunction with it. Typically, the position of the first battery terminal 21, located on the spring 60 side, changes in the S direction in conjunction with the expansion / contraction of the cell stack 12. To absorb such environment-dependent displacements of the first battery terminal 21, it is desirable that the first busbar 210 has flexibility.

[0053] Furthermore, variations in manufacturing may cause variations in the relative positional relationship between the first battery terminal 21 of the fuel cell stack 10 and the first terminal block 121 of the electrical equipment 110. To absorb such relative positional variations, it is desirable that the first busbar 210 be flexible.

[0054] Similarly, variations in manufacturing can cause variations in the relative position between the second battery terminal 22 of the fuel cell stack 10 and the second terminal block 122 of the electrical equipment 110. To absorb such relative position variations, it is desirable that the second busbar 220 be flexible.

[0055] From the above perspective, this disclosure proposes a busbar with appropriate flexibility. The following explanation will use the first busbar 210 as an example. Similar features are also applicable to the second busbar 220.

[0056] For simplicity, in the following explanation, the first busbar 210 will be simply referred to as "busbar 210," the first battery terminal 21 of the fuel cell stack 10 will be simply referred to as "battery terminal 21," and the first terminal block 121 of the electrical equipment 110 will be simply referred to as "terminal 121."

[0057] 3-1. Ensuring flexibility The bending stiffness of a plate-like member is expressed as the product of Young's modulus and the second moment of area. The second moment of area is proportional to the cube of the plate thickness. Therefore, as the plate thickness decreases, the bending stiffness of the plate-like member decreases. In other words, as the plate thickness decreases, the flexibility of the plate-like member increases.

[0058] One might consider simply making the busbar 210 thinner to increase its flexibility. However, reducing the cross-sectional area of ​​the busbar 210 increases its resistance, making it difficult to conduct large currents and also increasing heat generation. Therefore, a certain amount of cross-sectional area is necessary for the busbar 210.

[0059] Therefore, according to this embodiment, the busbar 210 is constructed from multiple thin metal plates instead of a single metal plate. In other words, a single metal plate is divided into multiple thin metal plates. As mentioned above, bending rigidity is proportional to the cube of the plate thickness, so even if the overall plate thickness is the same, the flexibility will be higher with multiple thin metal plates than with a single metal plate. That is, it is possible to increase the flexibility of the busbar 210 without increasing resistance.

[0060] Figure 8 is a schematic diagram illustrating an example of a busbar 210 using multiple metal plates 200. The multiple metal plates 200 are stacked. Here, "stacked" means arranged in layers and parallel to each other. Adjacent metal plates 200 do not necessarily need to be in contact with each other. Examples of materials for the metal plates 200 include copper, aluminum, and alloys containing a large amount of copper or aluminum.

[0061] The busbar 210 includes a first connection part 210A that connects to the battery terminal 21 of the fuel cell stack 10 and a second connection part 210B that connects to the terminal 121 of the electrical equipment 110. The first connection part 210A and the second connection part 210B are located apart from each other on the busbar 210. For example, the first connection part 210A and the second connection part 210B are located at both ends of the busbar 210.

[0062] In each of the first connection section 210A and the second connection section 210B, multiple metal plates 200 are joined to each other. In other words, the first connection section 210A and the second connection section 210B are formed by joining multiple metal plates 200 to each other. For example, the multiple metal plates 200 are joined by heat pressing. As another example, the multiple metal plates 200 may be joined by riveting. As yet another example, the multiple metal plates 200 may be joined by welding. Because multiple metal plates 200 are joined, the rigidity of the first connection section 210A and the second connection section 210B is increased, making it easier to connect to the battery terminals 21 and terminals 121. Preferably, the multiple metal plates 200 are joined over their entire surface. When the multiple metal plates 200 are joined over their entire surface, the first connection section 210A and the second connection section 210B can behave as a single plate, thereby preventing the outermost metal plate 200 from peeling off when the bolts are tightened.

[0063] The portion of the busbar 210 between the first connection portion 210A and the second connection portion 210B will hereafter be referred to as the "non-joined portion 210C". In the non-joined portion 210C, the multiple metal plates 200 are stacked without being joined (connected) to each other. In other words, in the non-joined portion 210C, the multiple metal plates 200 are stacked independently of each other. "Stacked" means arranged in layers and in parallel. Adjacent metal plates 200 may or may not be in contact with each other. In any case, the multiple metal plates 200 in the non-joined portion 210C are independent of each other without being joined (connected). It can also be said that the multiple metal plates 200 in the non-joined portion 210C are connected in parallel between the first connection portion 210A and the second connection portion 210B.

[0064] Preferably, the non-joint portion 210C includes a bent portion 210D formed by bending multiple metal plates 200. In the example shown in Figure 8, there are three bent portions 210D on the non-joint portion 210C. However, the number of bent portions 210D is not particularly limited. The curvature of each bent portion 210D is also not particularly limited. The non-joint portion 210C may be bent into a large arc shape. In other words, the non-joint portion 210C as a whole may form one large bent portion 210D.

[0065] As described above, the busbar 210 according to this embodiment includes a non-jointed portion 210C in which multiple metal plates 200 are laminated without being joined to each other. As stated above, bending rigidity is proportional to the cube of the plate thickness. Therefore, the flexibility of the non-jointed portion 210C is significantly higher compared to the case in which multiple metal plates 200 are joined to form a single thick metal plate. In addition, because multiple metal plates 200 are laminated, a sufficient cross-sectional area is secured for the entire non-jointed portion 210C, preventing an increase in resistance. In other words, it is possible to ensure the flexibility of the busbar 210 without increasing the resistance of the busbar 210.

[0066] The high flexibility of the non-connecting portion 210C means that the non-connecting portion 210C is easily deformable. Because the non-connecting portion 210C is easily deformable, the position of the first connecting portion 210A, which is connected to the battery terminal 21, can be easily changed. Therefore, displacement of the battery terminal 21 that depends on the environment can be easily absorbed.

[0067] Furthermore, because the non-connected portion 210C is easily deformable, the relative positional relationship between the first connection portion 210A and the second connection portion 210B can be easily changed. Therefore, variations in the relative positional relationship between the battery terminal 21 and terminal 121 caused by manufacturing variations, etc., can be easily absorbed.

[0068] In particular, as shown in Figure 8, if the non-joint portion 210C has at least one bent portion 210D, the non-joint portion 210C becomes easier to deform freely in the ST plane. That is, the non-joint portion 210C becomes easier to deform in both the S direction and the T direction. Therefore, it becomes possible to easily absorb various displacements of the battery terminal 21 that depend on the environment. For example, it becomes possible to easily absorb displacements in the S direction caused by expansion / contraction of the cell stack 12. It also becomes possible to easily absorb various variations in the relative positional relationship between the battery terminal 21 and terminal 121.

[0069] 3-2. Improved ease of assembly Regarding the assembly of the fuel cell unit 1 described above, consider the state shown in Figure 5. In the state shown in Figure 5, the first connection part 210A of the busbar 210 is already fixed to the battery terminal 21 of the fuel cell stack 10. On the other hand, the second connection part 210B of the busbar 210 is not yet fixed to the terminal 121 of the electrical equipment 110. This corresponds to a so-called "cantilever state". In this case, as shown in Figures 5 and 9, the busbar 210 bends due to gravity.

[0070] If the busbar 210 (non-connected portion 210C) is excessively flexible, the deflection of the busbar 210 (non-connected portion 210C) due to gravity will increase. As a result, in the state shown in Figure 5, the second connection portion 210B of the deflected busbar 210 may move significantly away from the position of the terminal 121. In addition, the deflected busbar 210 may interfere with (contact with) the case 130 of the electrical equipment unit 100 or other components. Therefore, it becomes difficult to smoothly assemble the busbar 210 to the terminal 121. In other words, the "assemblability" of the busbar 210 is reduced.

[0071] Therefore, this disclosure further proposes a technology that can ensure not only the flexibility of the busbar 210 but also its ease of assembly. In other words, this disclosure proposes a technology that can achieve both the flexibility and ease of assembly of the busbar 210.

[0072] Figure 10 is a schematic diagram illustrating an example of a busbar 210 using multiple metal plates 200. Explanations that overlap with the example shown in Figure 8 above are omitted as appropriate.

[0073] The multiple metal plates 200 include multiple types of metal plates with different thicknesses. For simplicity, the following explanation will describe the case where the multiple metal plates 200 include two types of metal plates with different thicknesses. The same applies to cases with three or more types.

[0074] Among the multiple metal plates 200, the relatively thin ones will be referred to as "first metal plate 201" below. On the other hand, among the multiple metal plates 200, the relatively thick ones will be referred to as "second metal plate 202" below. In other words, the multiple metal plates 200 include the first metal plate 201 and the second metal plate 202, which is thicker than the first metal plate 201. It should be noted that even the relatively thick second metal plate 202 is still quite thin compared to the multiple metal plates 200 as a whole.

[0075] The relatively thick second metal plate 202 has higher rigidity than the first metal plate 201 and is less susceptible to bending due to gravity. Even in the cantilevered state shown in Figure 9, the posture (shape) of the second metal plate 202 is easily maintained. Therefore, the second metal plate 202 contributes to maintaining the posture (shape) of the busbar 210 (non-joint portion 210C) during assembly. As a result, in the state shown in Figure 5, the second connection portion 210B of the busbar 210 is prevented from deviating significantly from the position of the terminal 121. In other words, in the state shown in Figure 5, the busbar 210 is held so that the second connection portion 210B is located near the terminal 121. Therefore, the ease of assembly of the busbar 210 is improved.

[0076] The rigidity and flexibility of the non-jointed portion 210C are dominated by the relatively thick second metal plate 202. However, even the relatively thick second metal plate 202 is still considerably thinner than the entirety of the multiple metal plates 200. Therefore, the flexibility of the non-jointed portion 210C is significantly higher compared to the case where multiple metal plates 200 are joined together to form a single thick metal plate.

[0077] The relatively thin first metal plate 201 does not increase the rigidity of the non-joint portion 210C. In other words, the relatively thin first metal plate 201 does not reduce the flexibility of the non-joint portion 210C. In this sense, the first metal plate 201 can be said to contribute to maintaining the flexibility of the busbar 210 (non-joint portion 210C). Furthermore, the first metal plate 201 ensures the overall cross-sectional area of ​​the non-joint portion 210C and contributes to reducing the resistance of the busbar 210.

[0078] The number of first metal plates 201 and second metal plates 202 is not particularly limited. However, even with just one second metal plate 202, the effect of improved assembly can be obtained. From the standpoint of flexibility, it is preferable to have as few second metal plates 202 as possible. Therefore, the number of second metal plates 202 may be as small as possible. On the other hand, the number of first metal plates 201 is appropriately determined based on, for example, the magnitude of the current flowing through the busbar 210.

[0079] Typically, the number of first metal plates 201 is greater than the number of second metal plates 202. Conversely, the number of second metal plates 202 is less than the number of first metal plates 201. This makes it possible to efficiently ensure low resistance, flexibility, and ease of assembly with respect to the busbar 210 without unnecessarily reducing flexibility.

[0080] The thicknesses of the first metal plate 201 and the second metal plate 202 are not particularly limited. As a guideline, the thickness of the first metal plate 201 is 0.3 mm or less. For example, the thickness of the first metal plate 201 may be 0.1 mm, 0.2 mm, 0.3 mm, etc. On the other hand, the thickness of the second metal plate 202 is approximately 0.5 mm or more. In this case, it becomes particularly easier to maintain the posture (shape) of the second metal plate 202 in the cantilevered state shown in Figure 9. For example, the thickness of the second metal plate 202 may be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 2 mm, etc.

[0081] 3-3. Effects As described above, the busbar 210 of the fuel cell unit 1 according to this embodiment includes a non-jointed portion 210C in which multiple metal plates 200 are laminated without being joined to each other. Compared to the case in which multiple metal plates 200 are joined to form a single thick metal plate, the flexibility of the non-jointed portion 210C is significantly higher. The high flexibility of the non-jointed portion 210C means that the non-jointed portion 210C is easily deformable. Because the non-jointed portion 210C is easily deformable, it is possible to easily absorb environmentally dependent displacement of the terminals and variations in the relative positional relationship between the terminals.

[0082] Furthermore, since multiple metal plates 200 are laminated, the cross-sectional area of ​​the non-jointed portion 210C as a whole is sufficiently secured, preventing an increase in resistance. In other words, it is possible to ensure the flexibility of the busbar 210 without increasing the resistance of the busbar 210.

[0083] Furthermore, the multiple metal plates 200 of the non-jointed portion 210C include a first metal plate 201 and a second metal plate 202 that is thicker than the first metal plate 201. The relatively thick second metal plate 202 has higher rigidity than the first metal plate 201 and is less susceptible to bending due to gravity. Therefore, the second metal plate 202 contributes to maintaining the posture (shape) of the busbar 210 (non-jointed portion 210C) during assembly. In other words, the second metal plate 202 improves the ease of assembly of the busbar 210. On the other hand, the first metal plate 201 contributes to maintaining the flexibility of the busbar 210 (non-jointed portion 210C) and reducing resistance.

[0084] Thus, according to this embodiment, it is possible to ensure "low resistance," "flexibility," and "ease of assembly" for the busbar 210 of the fuel cell unit 1.

[0085] Furthermore, in both the first connection section 210A and the second connection section 210B, multiple metal plates 200 are joined to each other. Because multiple metal plates 200 are joined, the rigidity of the first connection section 210A and the second connection section 210B is increased, making it easier to connect to the battery terminals 21 and terminals 121.

[0086] 4. Various examples of busbars The following describes various examples of the busbar 210 according to this embodiment.

[0087] 4-1. Example 1 Figure 11 is a schematic diagram showing a first example of the busbar 210. In this first example, there are two second metal plates 202. The two second metal plates 202 are positioned at both ends of the stacking direction of the multiple metal plates 200. Multiple first metal plates 201 are sandwiched between the two second metal plates 202. For example, each first metal plate 201 has a thickness of 0.2 mm, and each second metal plate 202 has a thickness of 1 mm.

[0088] 4-2. Second Example Figure 12 is a schematic diagram showing a second example of the busbar 210. In this second example, there are two or more first metal plates 201, and a second metal plate 202 is sandwiched between two or more first metal plates 201. In other words, the second metal plate 202 is not located at either end of the stacking direction of the multiple metal plates 200.

[0089] For example, the number of second metal plates 202 is 1. As shown in Figure 12, the second metal plate 202 has two opposing surfaces SU and SL. One or more first metal plates 201U are arranged on the surface SU side of the second metal plate 202. On the other hand, one or more first metal plates 201L are arranged on the surface SL side of the second metal plate 202. That is, the second metal plate 202 is sandwiched between one or more first metal plates 201U and one or more first metal plates 201L. For example, the thickness of each first metal plate 201 is 0.2 mm, and the thickness of the second metal plate 202 is 1 mm.

[0090] In the first example shown in Figure 11, the first metal plate 201 was sandwiched between two second metal plates 202. In this case, the second metal plates 202 on both sides of the first metal plate 201 may restrict the deformation of the first metal plate 201. If the deformation of the first metal plate 201 is restricted, the flexibility of the non-jointed portion 210C may be slightly reduced.

[0091] On the other hand, in the second example, the second metal plate 202 is sandwiched between multiple first metal plates 201. In other words, the first metal plates 201 are not sandwiched by the second metal plates 202. Therefore, the first metal plate 201 in the second example can be deformed more freely than the first metal plate 201 in the first example, without being constrained by the second metal plates 202. That is, in the second example, the flexibility of the non-jointed portion 210C is improved compared to the first example described above.

[0092] 4-3. Third Example Figure 13 is a schematic diagram showing a third example of the busbar 210. The third example is a modified version of the second example described above. Explanations that overlap with the second example described above will be omitted as appropriate.

[0093] In the third example, the number of first metal plates 201U present on the SU side of the second metal plate 202 is equal to the number of first metal plates 201L present on the SL side of the second metal plate 202. In other words, the multiple first metal plates 201 are equally divided between the SU side and the SL side by the second metal plate 202.

[0094] Although the rigidity of a single thin first metal plate 201 is extremely low, when multiple first metal plates 201 are in contact and bundled together, the rigidity increases to some extent. From the standpoint of the flexibility of the non-jointed portion 210C, it is preferable to have fewer first metal plates 201 bundled together. In the third example, since the multiple first metal plates 201 are evenly divided by the second metal plate 202, the number of first metal plates 201 bundled together is minimized. Therefore, the flexibility of the non-jointed portion 210C is improved compared to the second example described above.

[0095] 4-4. The fourth example Figure 14 is a schematic diagram showing a fourth example of the busbar 210. In Figure 14, the direction of gravity is indicated by an arrow. In the fourth example, of the multiple metal plates 200, the second metal plate 202 is positioned at the bottom in the direction of gravity. In other words, multiple first metal plates 201 are stacked on top of the second metal plate 202. For example, each first metal plate 201 has a thickness of 0.2 mm, and the second metal plate 202 has a thickness of 1 mm.

[0096] The relatively thin first metal plate 201 is prone to bending due to gravity. However, according to the fourth example, a second metal plate 202 is located below the first metal plate 201, and the first metal plate 201 is supported by the second metal plate 202. Therefore, bending of the first metal plate 201 due to gravity is prevented. As a result, the first metal plate 201 is prevented from bending and coming into contact with other components such as the electrical equipment 110. Even if other components are located near the busbar 210, it is possible to ensure a margin between the busbar 210 and the other components.

[0097] 4-5. The fifth example Figure 15 is a schematic diagram showing a fifth example of the busbar 210. In Figure 15, the direction of gravity is indicated by an arrow. In the fifth example, the second metal plate 202 is positioned on top of the multiple metal plates 200 in the direction of gravity. In other words, the second metal plate 202 is stacked on top of the multiple first metal plates 201. Also, the first metal plates 201 are not sandwiched between the multiple second metal plates 202. For example, each first metal plate 201 has a thickness of 0.2 mm, and the second metal plate 202 has a thickness of 1 mm.

[0098] Although the rigidity of a single thin first metal plate 201 is extremely low, when multiple first metal plates 201 come into contact and form a bundle, the rigidity increases to some extent. From the viewpoint of the flexibility of the non-jointed portion 210C, it is preferable to have fewer first metal plates 201 bundled together. In the fifth example, multiple first metal plates 201 tend to disperse in the direction of gravity and therefore do not tend to form a bundle. This is preferable from the viewpoint of the flexibility of the non-jointed portion 210C.

[0099] If there is sufficient margin between the busbar 210 and the surrounding components, the first metal plate 201 will not come into contact with the surrounding components, even in an arrangement like that of the fifth example.

[0100] 4-6. The sixth example Figure 16 is a schematic diagram showing a sixth example of the busbar 210. The first connection portion 210A of the busbar 210 is parallel to the S direction, and the second connection portion 210B intersects with the S direction. In other words, a plane parallel to the first connection portion 210A and a plane parallel to the second connection portion 210B intersect. Therefore, the non-joint portion 210C between the first connection portion 210A and the second connection portion 210B has at least one bent portion 210D.

[0101] In the example shown in Figure 16, the non-jointed section 210C has three bent sections 210D1, 210D2, and 210D3. Of these, bent section 210D3 is closest to the second connecting section 210B. At the bent section 210D3, the second metal plate 202 is located on the outer side of the multiple metal plates 200. The first metal plate 201 is located on the inner side of the second metal plate 202. Therefore, the length H2 of the second metal plate 202 between the second connecting section 210B and the bent section 210D3 is greater than the length H1 of the first metal plate 201 between the second connecting section 210B and the bent section 210D3 (H2 > H1).

[0102] In other words, at the non-jointed portion 210C, the total length of the second metal plate 202 is greater than the total length of the first metal plate 201. That is, at the non-jointed portion 210C, the second metal plate 202 is longer than the first metal plate 201. In this case, the length H2 of the second metal plate 202 between the second connecting portion 210B and the bent portion 210D3 is greater than the length H1 of the first metal plate 201 between the second connecting portion 210B and the bent portion 210D3 (H2 > H1).

[0103] Figure 17 is a conceptual diagram illustrating the effect of the busbar 210 shown in Figure 16. When the cell stack 12 expands / contracts in the S direction, the battery terminals 21 are displaced in the S direction. Consequently, the non-joint portion 210C deforms, and the first connection portion 210A of the busbar 210 connected to the battery terminals 21 also displaces in the S direction. The bent portion 210D3 of the non-joint portion 210C is displaced in the S direction by a displacement amount D. At this time, as shown in Figure 17, each metal plate 200 bends at the boundary between the second connection portion 210B and the non-joint portion 210C, and stress is generated.

[0104] The bending angles of each metal plate 200 at the boundary between the second connecting portion 210B and the non-connecting portion 210C are as follows: The bending angle θ1 of the inner first metal plate 201 is tan -1 It is expressed as (D / H1). On the other hand, the bending angle θ2 of the outer second metal plate 202 is tan -1This is expressed as (D / H2). As mentioned above, since length H2 is greater than length H1 (H2>H1), the angle of inclination θ2 is smaller than the angle of inclination θ1 (θ2<θ1).

[0105] Under the condition that the bending angle is the same, the stress increases as the plate thickness increases. By minimizing the bending angle θ2 of the relatively thicker second metal plate 202, it is possible to effectively suppress the maximum stress value of the busbar 210 as a whole.

[0106] 4-7. Example 7 Figure 18 is a schematic diagram showing a seventh example of the busbar 210. The seventh example is a modification of the sixth example described above. Explanations that overlap with the sixth example described above will be omitted as appropriate.

[0107] Let's consider the spacing W between multiple metal plates 200 at the non-jointed section 210C. The spacing W is the distance between the two outermost metal plates 200 of the stacked metal plates 200. The spacing W2 between the bent section 210D1 and the bent section 210D2 is greater than the spacing W1 between the bent section 210D1 and the first connecting section 210A (W2 > W1). Also, the spacing W3 between the bent section 210D3 and the bent section 210D2 is greater than the spacing W4 between the bent section 210D3 and the second connecting section 210B (W3 > W4). The spacing W1 and the spacing W4 may be the same. The spacing W2 and the spacing W3 may be the same.

[0108] In the section between the bent portion 210D1 and the bent portion 210D3, the separation widths W2 and W3 are relatively large, making it difficult for the metal plates 200 to come into contact with each other, and allowing the metal plates 200 to deform more freely. Also, because the separation width W3 is large, the difference between length H2 and length H1 becomes larger. Therefore, a greater effect on suppressing the maximum stress value described in the sixth example can be expected.

[0109] 5. Others The features of the first busbar 210 described above can also be applied to the second busbar 220. This makes it possible to ensure low resistance, flexibility, and ease of assembly for the second busbar 220 as well. [Explanation of Symbols]

[0110] 1 Fuel cell unit 10 Fuel Cell Stacks 11 fuel cell cells 12-cell stack 21 1st battery terminal 22 2nd battery terminal 30 stackable cases 100 Electrical Equipment Department 110 Electrical equipment 121 1st terminal block 122 2nd terminal block 130 cases 200 metal plate 201 1st metal plate 202 Second metal plate 210 First Bus Bar 210A First connection section 210B Second connection section 210C Non-joint part 210D bent part 220 Second Bus Bar

Claims

1. A fuel cell stack consisting of multiple fuel cell cells stacked on top of each other, Electrical equipment and, A busbar, which is made up of multiple stacked metal plates, electrically connects the terminals of the fuel cell stack and the terminals of the electrical equipment. Equipped with, The aforementioned busbar is A first connecting portion in which the plurality of metal plates are joined to each other by the first method, A second connecting portion in which the plurality of metal plates are joined to each other by a second method, A non-jointed portion exists between the first connecting portion and the second connecting portion, and the plurality of metal plates are stacked without being joined to each other. Includes, The first connection portion of the busbar is connected to the terminal of the fuel cell stack by a third method different from the first method, The second connection portion of the busbar is connected to the terminal of the electrical equipment by a fourth method different from the second method, The plurality of metal plates include a first metal plate and a second metal plate that is thicker than the first metal plate. Fuel cell unit.

2. A fuel cell unit according to claim 1, The non-jointed portion includes a bent portion formed by bending the plurality of metal plates. The first method described above is heat bonding, crimping, or welding. The second method described above is heat bonding, crimping, or welding. The third method described above is fastening with bolts, The fourth method described above is fastening with bolts. Fuel cell unit.

3. A fuel cell unit according to claim 1, The number of the second metal plates is less than the number of the first metal plates. Fuel cell unit.

4. A fuel cell unit according to claim 3, The number of the second metal plates is 1. Fuel cell unit.

5. A fuel cell unit according to any one of claims 1 to 4, The number of the first metal plates is two or more. The second metal plate is sandwiched between the two or more first metal plates. Fuel cell unit.

6. A fuel cell unit according to claim 5, The second metal plate has a first surface and a second surface opposite to the first surface. The number of first metal plates present on the first surface side of the second metal plate is equal to the number of first metal plates present on the second surface side of the second metal plate. Fuel cell unit.

7. A fuel cell unit according to any one of claims 1 to 4, Of the plurality of metal plates, the second metal plate is positioned at the bottom in the direction of gravity. Fuel cell unit.

8. A fuel cell unit according to any one of claims 1 to 4, Of the plurality of metal plates, the second metal plate is positioned at the top in the direction of gravity. Fuel cell unit.

9. A fuel cell unit according to any one of claims 1 to 4, The non-jointed portion includes a bent portion formed by bending the plurality of metal plates, At the bent portion closest to the second connection portion, the second metal plate is located on the outermost side among the plurality of metal plates. Fuel cell unit.

10. A fuel cell unit according to any one of claims 1 to 4, In the non-jointed portion, the second metal plate is longer than the first metal plate. Fuel cell unit.

11. A method for assembling a fuel cell unit including a fuel cell stack in which multiple fuel cell cells are stacked and electrical equipment, A step of forming a busbar in which a plurality of metal plates are laminated, including a first metal plate and a second metal plate that is thicker than the first metal plate, The steps include electrically connecting the first connection portion of the busbar to the terminal of the fuel cell stack, The process of electrically connecting the second connection portion of the busbar to the terminal of the electrical equipment. Includes, The process of forming the busbar includes joining the multiple metal plates to each other at the first and second connection portions, without joining them to each other at the non-joined portion between the first and second connection portions. How to assemble a fuel cell unit.

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