Terminal structure for cell voltage measurement of fuel battery stack

Abstract

To provide a terminal structure for a cell voltage measurement of a fuel battery stack, capable of reducing the number of steps by a simple assembly operation.SOLUTION: A terminal structure for a cell voltage measurement of a fuel battery stack 1, includes: a tab 31 having a plate shape extending forward from a front edge part of a separator 21 of a fuel battery cell 2; a connection terminal 32 having a plate shape extending in the front-rear direction and connectable to a voltage measurement device via a cable 33; and an insulating member 34 having elasticity in a stacking direction. The tab 31 and the connection terminal 32 are sandwiched in a stacking direction by the insulating member 34 to form a terminal unit 3 in a state where at least a part of them overlap and contact each other when viewed from the stacking direction, and the terminal unit 3 is provided corresponding to each of the plurality of fuel battery cells 2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a terminal structure for measuring the cell voltage of a fuel cell stack.

Background Art

[0002] As a conventional technique for measuring the voltage of each cell of a fuel cell stack, for example, Patent Document 1 discloses an assembly method of a cell voltage detection unit in which a plurality of cell terminals extending from a separator of a fuel cell are aligned by a comb-shaped member, and then a waterproof means and a cell voltage measuring means are sequentially mounted on the plurality of cell terminals from above.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, with the miniaturization and high output of fuel cell cells, the thickness of each fuel cell cell stacked as a fuel cell stack has become thinner (the interval between cells has become narrower), and the thickness of the terminals (cell-side terminals) provided on the electrodes of each fuel cell cell for measuring the cell voltage has also become thinner. For this reason, in the assembly process of the fuel cell stack, it may become difficult to attach the terminal (measurement-side terminal) connected to the voltage measurement device to the cell-side terminal due to bending (breaking) of the electrode or cell-side terminal of each fuel cell cell.

[0005] In the prior art disclosed in the above-mentioned Patent Document 1, by alternately laminating two types of separators with the positions of the cell-side terminals (cell terminals) shifted, the cell-side terminals are arranged in two rows and the number of cell-side terminals included in one row is halved. Thus, the interval between the cell-side terminals in each row is widened to twice that when the positions of the cell-side terminals are not shifted. After aligning the cell-side terminals in each row with a comb-shaped member, the measurement-side terminals (waterproof means and cell voltage measurement means) are mounted.

[0006] However, in the above prior art, since the process of aligning the cell-side terminals and the process of mounting the measurement-side terminals need to be performed as separate processes (subsequent processes to the lamination process) from the lamination process of each fuel cell in the fuel cell stack, there is a problem that the assembly work of the fuel cell stack becomes complicated and the man-hours increase. Also, when the cell-side terminals are arranged in a staggered (stepped) manner as in the prior art, a plurality of types of cells (separators) are required due to the difference in the arrangement of the cell-side terminals, which also causes a problem of complicating parts management and increasing manufacturing costs.

[0007] The present invention has been made paying attention to the above points, and an object thereof is to provide a terminal structure for measuring the cell voltage of a fuel cell stack that can reduce man-hours with a simple assembly operation.

Means for Solving the Problems

[0008] To achieve the above object, one aspect of the present invention provides a terminal structure for measuring cell voltage for measuring the cell voltage of each cell in a fuel cell stack in which a plurality of fuel cell cells are stacked. The terminal structure for measuring cell voltage of this fuel cell stack includes a conductive cell-side terminal formed in a plate shape extending in a crossing direction crossing the stacking direction of the fuel cell stack from the peripheral edge of the electrode of the fuel cell cell, a conductive measurement-side terminal formed in a plate shape extending in the crossing direction and configured to be connectable to a voltage measurement device, and an insulating member having elasticity in the stacking direction. The cell-side terminal and the measurement-side terminal form a terminal unit by being sandwiched by the insulating member in the stacking direction in a state where at least a part of each other overlaps and contacts when viewed from the stacking direction, and the terminal unit is provided corresponding to each of the plurality of fuel cell cells.

Advantages of the Invention

[0009] According to the terminal structure for measuring cell voltage of the fuel cell stack according to the present invention, since it is possible to perform the assembly process of the terminal unit corresponding to each at the same timing as the stacking process of each fuel cell cell, the assembly work of the fuel cell stack can be simplified and the man-hours can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing the appearance of a fuel cell stack to which a terminal structure for measuring cell voltage according to an embodiment of the present invention is applied. In each of the figures described below, the direction of arrow F indicates the front-rear direction of the fuel cell stack with the front being indicated, the direction of arrow U indicates the vertical direction of the fuel cell stack with the upper side being indicated, and the direction of arrow O indicates the outward direction in the width direction of the fuel cell stack.

[0012] In FIG. 1, in the fuel cell stack 1 to which the terminal structure for measuring cell voltage of the present embodiment is applied, a plurality of fuel cells 2 are stacked in the vertical direction between upper and lower clamping plates 11. The upper and lower clamping plates 11 are formed in a rectangular shape in plan view, and hold each fuel cell 2 in a state of being pressurized in the stacking direction (vertical direction) by clamping bolts 12 arranged at the four corners thereof. In the present embodiment, an example in which each fuel cell 2 is horizontally placed and stacked vertically will be described, but it is also possible to arrange each fuel cell 2 vertically and side by side in the front-rear or left-right direction. When each fuel cell 2 is placed vertically, the clamping plates 11 are also arranged vertically at both the front-rear or left-right ends.

[0013] Each fuel cell 2 stacked in the fuel cell stack 1 is provided with a terminal unit 3 for measuring the voltage of each cell. Each terminal unit 3 forms a part of the electrical wiring that connects between the electrodes of each fuel cell 2 and a voltage measuring device (not shown). Each terminal unit 3 in the present embodiment extends forward, for example, from the front edge of each fuel cell 2 in one of the cross directions (front-rear direction and width direction) that intersects the stacking direction (vertical direction) of the fuel cell stack 1.

[0014] FIG. 2 is an enlarged front view showing a peripheral region A of the terminal unit 3 surrounded by a dashed-dotted line in FIG. 1. Further, FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2. Furthermore, FIG. 4 is an enlarged plan view showing the terminal unit 3 disassembled and each element individually.

[0015] As shown in FIGS. 2 to 4, each terminal unit 3 includes a tab 31 for measuring the cell voltage provided in each fuel cell 2, a connection terminal 32 for measuring the cell voltage that can be connected to a voltage measuring device (not shown) via a cable 33, and an insulating member 34 that sandwiches the tab 31 and the connection terminal 32 in the stacking direction. In this embodiment, the tab 31 for measuring the cell voltage corresponds to the "cell-side terminal" of the present invention, and the connection terminal 32 for measuring the cell voltage corresponds to the "measurement-side terminal" of the present invention.

[0016] Each fuel cell 2 is configured such that a pair of separators (electrodes) 21 sandwich a membrane electrode assembly (MEA) 22 (FIGS. 2 and 3). The membrane electrode assembly 22 is composed of a catalyst layer, an electrolyte membrane, a gas diffusion layer (GDL), and the like. In this embodiment, the membrane electrode assembly 22 includes a metal plate 23 that contacts the upper surface of the lower separator 21 (FIGS. 3 and 4). The metal plate 23 is formed in a shape smaller than the outer shape of the lower separator 21 in plan view. That is, there is a peripheral portion on the upper surface of the lower separator 21 that is not covered by the metal plate 23. Note that FIG. 4 shows a state in which the membrane electrode assembly 22 other than the upper separator 21 and the metal plate 23 is removed.

[0017] The tab 31 (cell-side terminal) for measuring the cell voltage is made of a conductive material such as titanium, stainless steel, or carbon, and is formed in a thin plate shape extending forward from the front edge of the separator 21 on the lower side of the fuel cell 2. The tab 31 is formed in a rectangular shape in plan view, and the rear end portion of the lower surface contacts the upper surface of the lower separator 21, and the rear end surface contacts the front end surface of the metal plate 23 (FIGS. 3 and 4). That is, the tab 31 forms a part of the electrode of the fuel cell 2 by being electrically connected to the lower separator 21 and the metal plate 23. The thickness of the tab 31 can be made as thin as 1 mm or less (for example, 0.6 mm, etc.). A through hole 31A penetrating in the stacking direction (vertical direction) is formed in the tab 31. The through hole 31A of the tab 31 is provided at a position spaced forward from the front end surface of the lower separator 21. The through hole 31A of the tab 31 in the present embodiment has a circular shape in plan view (FIG. 4).

[0018] The connection terminal 32 (measurement-side terminal) for measuring the cell voltage is made of a conductive material such as a metal plate or copper, brass, or stainless steel plated with gold, and is formed in a thin plate shape extending in the front-rear direction. As the material of the connection terminal 32, various materials can be used as long as they are excellent in electrical conduction and are less likely to cause electrolytic corrosion with the surface material of the tab 31. One end of the cable 33 is electrically joined to the front side portion of the upper surface (or lower surface) of the connection terminal 32. The other end of the cable 33 can be connected to a voltage measuring device. That is, the connection terminal 32 is configured to be electrically connectable to the voltage measuring device via the cable 33. The thickness of the connection terminal 32 is here made approximately the same as the thickness of the tab 31 (FIGS. 2 and 3). A circular through hole 32A penetrating in the stacking direction (vertical direction) is formed in the rear side portion of the connection terminal 32 in the same manner as the through hole 31A of the tab 31 (FIGS. 3 and 4). The tab 31 and the connection terminal 32 are arranged vertically so that the positions of the respective through holes 31A and 32A are aligned (coaxial). In the present embodiment, the front side portion of the lower surface of the tab 31 and the rear side portion of the upper surface of the connection terminal 32 are in contact with each other, so that the tab 31 and the connection terminal 32 are electrically connected.

[0019] The insulating member 34 has at least elasticity in the stacking direction (vertical direction) of the fuel cell stack 1. The insulating member 34 is formed in a plate shape extending in the front-rear direction and has a shape capable of covering at least the overlapping portion of the tabs 31 and the connection terminals 32 that are arranged one above the other in the vertical direction. When it is necessary to ensure the thickness of the insulating member 34, for example, the insulating member 34 may be formed by bonding an elastic material to a relatively hard base material such as polyphenylene sulfide (PPS).

[0020] A circular through-hole 34A penetrating in the stacking direction (vertical direction) is formed in the central portion in the longitudinal direction of the insulating member 34, in the same manner as the through-holes 31A and 32A of the tab 31 and the connection terminal 32 (FIGS. 3 and 4). The insulating member 34 is arranged so as to overlap above the tab 31 such that the positions of the through-holes 31A and 32A of the tab 31 and the connection terminal 32 and the position of the through-hole 34A of the insulating member 34 are aligned vertically. In the present embodiment, the lower surface of the insulating member 34 abuts against the upper surface of the tab 31 in the same terminal unit 3, and the upper surface of the insulating member 34 abuts against the lower surface of the connection terminal 32 in the terminal unit 3 adjacent above (FIGS. 2 and 3). The upper surface of the insulating member 34 in the terminal unit 3 arranged in the uppermost layer of the fuel cell stack 1 abuts against the lower surface of the upper tightening plate 11, and the lower surface of the connection terminal 32 in the terminal unit 3 arranged in the lowermost layer of the fuel cell stack 1 abuts against the upper surface of the lower tightening plate 11 via a separately provided insulating member (not shown).

[0021] In each terminal unit 3 corresponding to each fuel cell 2 stacked in the fuel cell stack 1, the tab 31, the connection terminal 32, and the insulating member 34 are arranged one above the other in the vertical direction as described above. The terminal units 3 are arranged one above the other such that the positions of the respective through-holes 31A, 32A, and 34A are further aligned vertically. With such an arrangement, the tab 31 and the connection terminal 32 of each terminal unit 3 are sandwiched in the stacking direction (vertical direction) by the insulating member 34 in the same terminal unit 3 and the insulating member 34 in the terminal unit 3 adjacent below (in the case of the lowermost terminal unit 3, a separately provided insulating member).

[0022] In the through holes 31A, 32A, and 34A of all the terminal units 3 arranged one above the other as described above, a rod-shaped restricting member 35 having insulation is commonly inserted (FIGS. 2 and 3). In the present embodiment, the restricting member 35 is formed in a columnar shape having a diameter smaller than that of each of the through holes 31A, 32A, and 34A, and restricts the movement of the tab 31, the connection terminal 32, and the insulating member 34 in the front-rear direction and the width direction in each terminal unit 3. In other words, the restricting member 35 has a positioning function of aligning the tabs 31, the connection terminals 32, and the insulating members 34 of all the terminal units 3 in a single row in the vertical direction. The overall length of the restricting member 35 is designed to be shorter than the distance between the upper and lower tightening plates 11 in a state where each fuel cell 2 and each terminal unit 3 are pressurized in the stacking direction with a required tightening force by the upper and lower tightening plates 11 and the tightening bolts 12 (FIG. 1).

[0023] Next, the assembly process of the fuel cell stack 1 in the present embodiment will be described. In the assembly work of the fuel cell stack 1 to which the terminal structure for cell voltage measurement as described above is applied, it is possible to stack the fuel cells 2 and the terminal units 3 of each layer at the same timing.

[0024] Specifically, when assembling the fuel cell stack 1 in which N fuel cells 2 and terminal units 3 are stacked, first, on the upper surface of the lower tightening plate 11, the connection terminal 32 and the cable 33 of the first-layer terminal unit 3 are arranged via an insulating member prepared separately from the N terminal units 3. Then, the first-layer fuel cell 2 is arranged on the upper surface of the lower tightening plate 11 so that the tab 31 of the first-layer fuel cell 2 overlaps the connection terminal 32. Further, the insulating member 34 of the first-layer terminal unit 3 is stacked on the tab 31 of the first-layer fuel cell 2. At this time, the positions of the tab 31, the connection terminal 32, and the insulating member 34 are adjusted so that the positions of the through holes 31A, 32A, and 34A of the first layer are aligned vertically.

[0025] When the fuel cell unit 2 and the terminal unit 3 of the first layer are arranged, the connection terminals 32 and the cables 33 of the terminal unit 3 of the second layer are arranged on the insulating member 34 of the terminal unit 3 of the first layer. Then, the fuel cell unit 2 of the second layer is arranged on the fuel cell unit 2 of the first layer so that the tab 31 of the fuel cell unit 2 of the second layer overlaps the connection terminal 32, and further, the insulating member 34 of the terminal unit 3 of the second layer is superposed on the tab 31 of the fuel cell unit 2 of the second layer. At this time, the positions of the tab 31, the connection terminal 32, and the insulating member 34 are adjusted so that the positions of the through holes 31A, 32A, and 34A of the first and second layers are aligned vertically. Thereafter, in the same manner as the second layer, the fuel cell units 2 and the terminal units 3 of the third to Nth layers are sequentially stacked upward.

[0026] When the fuel cell unit 2 and the terminal unit 3 of the Nth layer are arranged, the restricting member 35 is inserted into the through holes 31A, 32A, and 34A of all the terminal units 3. Note that, at the stage when a certain number of layers of the terminal units 3 are arranged, the restricting member 35 may be inserted into the through holes 31A, 32A, and 34A, and the terminal units 3 may be stacked with reference to the restricting member 35 in the subsequent layers. Finally, an upper tightening plate 11 is superposed on the fuel cell unit 2 and the terminal unit 3 of the Nth layer, and the tightening bolts 12 at the four corners are tightened substantially evenly, so that the fuel cell units 2 and the terminal units 3 of each layer are held in a state of being pressurized in the stacking direction.

[0027] At this time, the insulating members 34 of the respective terminal units 3 are each compressed in the stacking direction, and the respective elastic forces act on the tab 31 and the connection terminal 32 sandwiched between the adjacent insulating members 34. As a result, stable electrical contact can be obtained between the tab 31 and the connection terminal 32. Further, in the pressurized state, since the thickness of each terminal unit 3 becomes the same as the thickness of each fuel cell unit 2, it is not necessary to arrange the cell side terminals in a staggered (stepped) manner as in the above-described prior art, and the types of the separators 21 of the fuel cell units 2 are reduced as compared with the prior art.

[0028] As described above, in the cell voltage measurement terminal structure of the fuel cell stack 1 according to the present embodiment, the tab 31 (cell-side terminal) for cell voltage measurement is formed in a plate shape extending forward from the front edge portion of the separator 21 of the fuel cell 2, and the connection terminal 32 (measurement-side terminal) configured to be connectable to the voltage measurement device via the cable 33 is formed in a plate shape extending in the front-rear direction. These tabs 31 and connection terminals 32 are sandwiched in the stacking direction by an elastic insulating member 34 in a state where at least a part of each other overlaps and contacts when viewed from the stacking direction of the fuel cell stack 1, forming a terminal unit 3, and the terminal unit 3 is provided corresponding to each of the plurality of fuel cells 2.

[0029] According to such a cell voltage measurement terminal structure, in the assembly work of the fuel cell stack 1, the assembly process of the corresponding terminal unit 3 can be performed at the same timing as the stacking process of each fuel cell 2. Therefore, the assembly work of the fuel cell stack 1 can be simplified and the man-hours can be reduced. Further, since the tabs 31 and the connection terminals 32 are sandwiched by the elastic insulating member 34, by appropriately adjusting the hardness and thickness of the insulating member 34, the contact pressure between the tabs 31 and the connection terminals 32 can be made appropriate, and it is also possible to easily cope with design changes such as the thickness of the fuel cell 2.

[0030] Further, in the cell voltage measurement terminal structure of the fuel cell stack 1 according to the present embodiment described above, the terminal units 3 corresponding to each fuel cell 2 are arranged in a single row in the stacking direction. As a result, it is possible to make the separators 21 of each fuel cell 2 stacked in the fuel cell stack 1 a single type (common shape), so that parts management can be easily performed and the manufacturing cost can be reduced. Further, in the pressurized state, since the thickness of each fuel cell 2 and the thickness of each terminal unit 3 are the same, the error in the thickness of each individual fuel cell 2 and the error in the thickness of the fuel cell stack 1 (the total thickness of the stacked fuel cells 2) can be absorbed by the expansion and contraction of the insulating member 34 of each terminal unit 3.

[0031] Also, in the terminal structure for measuring the cell voltage of the fuel cell stack 1 according to the above-described embodiment, the tab 31, the connection terminal 32, and the insulating member 34 each have through holes 31A, 32A, and 34A at positions overlapping each other when viewed from the stacking direction, and a restricting member 35 is commonly inserted into each of the through holes 31A, 32A, and 34A. By providing such a restricting member 35, the movement of the tab 31, the connection terminal 32, and the insulating member 34 in the front-rear direction and the width direction in each terminal unit 3 is restricted, so that the electrical contact between the tab 31 and the connection terminal 32 can be further stabilized.

[0032] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible based on the technical idea of the present invention. For example, in the above-described embodiment, an example in which the insulating member 34 has a shape covering the overlapping portion of the tab 31 and the connection terminal 32 has been shown (FIGS. 3 and 4). However, the insulating member 34 may have a shape covering not only the overlapping portion of the tab 31 and the connection terminal 32 but also the entire tab 31 and the connection terminal 32, so that the insulating member 34 also serves as an insulating protection material from the outside. A modified example of the insulating member 34 in this case will be specifically described with reference to FIG. 5.

[0033] FIG. 5 is a plan view and a side view showing a modified example of the insulating member 34 related to the above-described embodiment. In the modified example of FIG. 5, the insulating member 34 has a shape that covers the entire tab 31 and the connection terminal 32. Further, the insulating member 34 has a region that does not overlap with the tab 31 and the connection terminal 32 at its peripheral edge when viewed from the stacking direction, and fitting portions 34B for fixing the insulating members sandwiching the tab 31 and the connection terminal 32 to each other are provided at the four corners of this region (plan view in the upper part of FIG. 5). Each fitting portion 34B has a concave portion recessed upward formed on the lower surface of the upper insulating member 34 among the upper and lower insulating members 34 sandwiching the tab 31 and the connection terminal 32, and a convex portion protruding upward formed on the upper surface of the lower insulating member 34 (side view in the lower part of FIG. 5). According to such a modified example of the insulating member 34, it is possible to surely prevent displacement of the tab 31 and the connection terminal 32, and further stabilize the electrical contact between the tab 31 and the connection terminal 32.

[0034] In addition, in the above-described embodiment, an example in which one regulating member 35 formed in a columnar shape is inserted into each of the through holes 31A, 32A, and 34A is shown. However, for example, a pair of through holes may be formed in each of the tab 31, the connection terminal 32, and the insulating member 34 of each terminal unit 3, and the two regulating members 35 may be inserted into the pair of through holes, respectively. Thereby, since the rotation of the tab 31 and the connection terminal 32 around the regulating member 35 is also regulated, the electrical contact between the tab 31 and the connection terminal 32 can be further stabilized. Note that even if each of the through holes 31A, 32A, and 34A is polygonal and a single regulating member 35 formed in a polygonal prism corresponding thereto is used, it is possible to regulate the rotation of the tab 31 and the connection terminal 32.

[0035] Furthermore, in the above-described embodiment, an example in which each terminal unit 3 is arranged in a single row in the stacking direction has been described. However, for example, as shown in the enlarged front view of FIG. 6, the terminal units 3 may be arranged in a staggered (stepped) manner in two rows. When the terminal units 3 are arranged in two rows, the thickness of the insulating member 34 of each terminal unit 3 becomes approximately twice the thickness of the insulating member 34 in the case of the above-described embodiment. Even when the terminal units 3 are arranged in a plurality of rows in this way, the stacking process of each fuel cell 2 and the assembling process of each terminal unit 3 can be performed at the same timing, so that it becomes possible to simplify the assembly work of the fuel cell stack 1 and reduce the man-hours.

Explanation of Signs

[0036] 1…Fuel cell stack 11…Tightening plate 12…Tightening bolt 2…Fuel cell 21…Separator (electrode) 22…Membrane electrode assembly 23…Metal plate 3…Terminal unit 31…Tab (cell side terminal) 31A, 32A, 34A…Through hole 32…Connection terminal (measurement side terminal) 33…Cable 34…Insulating member 34B…Fitting portion 35…Regulating member

Claims

1. A terminal structure for measuring the cell voltage of each fuel cell in a fuel cell stack formed by stacking a plurality of fuel cells, a conductive cell-side terminal formed in a plate shape extending in a direction intersecting the stacking direction of the fuel cell stack from the peripheral edge of the electrode of the fuel cell, a conductive measurement-side terminal configured to be connectable to a voltage measurement device and formed in a plate shape extending in the intersecting direction, and an insulating member having elasticity in the stacking direction, wherein the cell-side terminal and the measurement-side terminal are sandwiched by the insulating member in the stacking direction in a state where at least a part of each other overlaps and contacts when viewed from the stacking direction to form a terminal unit, and the terminal unit is provided corresponding to each of the plurality of fuel cells. A terminal structure for measuring the cell voltage of a fuel cell stack, characterized in that.

2. The terminal structure for measuring the cell voltage of a fuel cell stack according to claim 1, wherein the terminal units corresponding to the plurality of fuel cells are arranged in a row in the stacking direction.

3. The cell-side terminal, the measurement-side terminal, and the insulating member each have a through hole penetrating in the stacking direction at a position overlapping each other when viewed from the stacking direction, and a rod-shaped regulating member having insulating properties is commonly inserted into each of the through holes. The terminal structure for measuring the cell voltage of a fuel cell stack according to claim 1, characterized in that.

4. The insulating member has a region at the peripheral edge that does not overlap the cell-side terminal and the measurement-side terminal when viewed from the stacking direction, and at least one fitting portion for fixing the insulating members sandwiching the cell-side terminal and the measurement-side terminal to each other is provided in the region. The terminal structure for measuring the cell voltage of a fuel cell stack according to claim 1, characterized in that.

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