Separator for fuel cells

Abstract

This specification provides a separator for fuel cells, which facilitates the separation of lower separators when the top separator is removed from a stack of multiple separators. [Solution] The separator disclosed herein comprises a rectangular flat substrate, a plurality of parallel gas flow channel grooves provided in the substrate, and positioning protrusions provided at least two of the four corners of the substrate. The width of the positioning protrusions is greater than the width of the gas flow channel grooves, and the height is greater than the depth of the gas flow channel grooves. The positioning protrusions are hollow inside, and their thickness is basically the same as the thickness of the substrate. However, in the separator disclosed herein, the positioning protrusions are provided with thicker sections whose thickness is greater than the thickness of the substrate.

Description

Technical Field

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[0001] The technology disclosed in this specification relates to a separator for a fuel cell.

Background Art

[0002] In a fuel cell, a separator is disposed between two adjacent membrane electrode assemblies (MEA). The separator for a fuel cell is often made of a metal plate with a thickness of 1.0 mm or less. The separator is provided with gas flow channels through which oxygen (air) or hydrogen flows. In the manufacturing process of a fuel cell, a plurality of separators are stacked and prepared. The gas flow channels are formed by pressing a thin flat substrate. The gas flow channels are concave-shaped when viewed from one side of the substrate and convex-shaped when viewed from the opposite side. That is, a convex (concave) shape of the same size is formed on the back side of the concave (convex) shape on one side of the substrate. Therefore, when a plurality of separators are stacked, the upper convex (concave) shape and the convex (concave) shape overlap and air is trapped between them, making it difficult to pick them up one by one.

[0003] Patent Document 1 discloses a technique for making it easier to lift only the uppermost separator by feeding air between the second separator from the top and the uppermost separator when lifting the uppermost separator. ]>

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] This specification provides a technique for making it easier to separate the lower separators when picking up the top separator from a stack of multiple separators, by modifying the shape of the separators. [Means for solving the problem]

[0006] The separator disclosed herein comprises a rectangular flat substrate, a plurality of parallel gas flow channel grooves provided in the substrate, and positioning protrusions provided at least two at the four corners of the substrate. The width of the positioning protrusions is greater than the width of the gas flow channel grooves, and the height is greater than the depth of the gas flow channel grooves. The gas flow channel grooves and positioning protrusions are manufactured by press-forming the substrate. Therefore, the positioning protrusions are hollow inside, and their thickness is basically the same as the thickness of the substrate. However, in the separator disclosed herein, the positioning protrusions are provided with thicker sections whose thickness is greater than the thickness of the substrate.

[0007] Without positioning protrusions, when two separators are stacked, the i-th gas flow channel groove of one separator and the (i+1)-th gas flow channel groove of the other separator may overlap incorrectly. In other words, the two separators may overlap misaligned. In the case of two separators with the positioning protrusions described above, the positioning protrusions begin to overlap before the gas flow channel grooves. Because the positioning protrusions overlap at least two locations on the substrate, the two separators overlap precisely. This prevents misalignment where gas flow channel grooves at different positions overlap on the upper and lower separators. Furthermore, because the positioning protrusions of the two stacked separators overlap securely, the thick plates of the two separators also overlap securely. This overlap of the thick plates ensures a gap between the two separators. This prevents the lower separator from remaining overlapped when the upper separator is picked up. In addition, positioning protrusions are provided at the corners of the substrate, and when the upper separator is lifted, the upper separator begins to separate from the lower separator at the corner where the positioning protrusions are located. Air enters inward from the corner where the upper and lower separators begin to separate, making it easier for the upper separator to separate from the lower separator. By employing the technology disclosed herein, the lower separators become easier to separate when the top separator is lifted from a stack of multiple separators.

[0008] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view of the separator in the embodiment. [Figure 2] This is a cross-sectional view of the separator along line II-II in Figure 1. [Figure 3] Figure 3(a) is a cross-sectional view of two overlapping separators (Example). Figure 3(b) is a cross-sectional view of two overlapping separators (Conventional Example). [Figure 4] This is a cross-sectional view showing the upper separator being lifted from the end. [Figure 5]A cross-sectional view of two overlapping separators (modified example). [Modes for carrying out the invention]

[0010] The separator 10 of the embodiment will be described with reference to the drawings. The separator 10 is a component placed between two adjacent membrane electrode assemblies (MEAs) in a fuel cell. Figure 1 shows a plan view of the separator 10, and Figure 2 shows a cross-sectional view of the separator 10 along the line II-II in Figure 1.

[0011] The separator 10 is a thin metal plate provided with a gas flow channel groove 12 and a positioning projection 13. The metal plate that serves as the base material for the separator 10 is referred to as the substrate 11 in this specification. The gas flow channel groove 12 and the positioning projection 13 are manufactured by press working. Therefore, the gas flow channel groove 12 is concave on one side of the substrate 11 and convex on the opposite side. Conversely, the positioning projection 13 is convex on one side of the substrate 11 and concave on the opposite side. Thus, the gas flow channel groove 12 becomes a recess made of the substrate 11 with a thickness Ta, and the positioning projection 13 becomes a dome shape made of the same thickness Ta. However, the positioning projection 13 includes a thick plate portion 13b where the plate thickness Tb is greater than the substrate thickness Ta (see Figure 2).

[0012] The thick plate section can be formed by modifying the press die. Specifically, the die that holds the substrate is provided with two closely spaced protrusions, and a recess between the adjacent protrusions. When the substrate is placed in the die and the die is closed, the thickness of the plate becomes thinner in the area between the protrusions, and the metal extruded by the protrusions accumulates in the recess, forming the thick plate section.

[0013] Although the gas flow channel groove 12 is a single groove across the entire substrate 11, when viewed locally it appears as multiple parallel grooves. For example, in Figure 1, line II-II crosses three parallel gas flow channel grooves 12. Thus, the gas flow channel groove 12 only needs to appear as multiple parallel grooves when viewed locally on the substrate 11. Although gas flow channel grooves 12 are provided on both sides of the substrate 11, the gas flow channel grooves on the other side are omitted from the illustration. In a fuel cell stack, oxygen flows through the gas flow channel groove on one side of the separator 10, and hydrogen flows through the gas flow channel groove on the other side.

[0014] The substrate 11 is rectangular when viewed from above, and the positioning protrusions 13 are provided at the two diagonal corners of the rectangular substrate 11.

[0015] As shown in Figure 2, the height Hb of the positioning projection 13 is greater than the groove depth Da of the gas flow channel groove 12. Also, the width Wb of the positioning projection 13 is greater than the groove width Wa of the gas flow channel groove 12. In one example, the groove width Wa of the gas flow channel groove 12 is about 1 [mm], and the width Wb of the positioning projection 13 is about 5 [mm]. In another example, the groove depth Da of the gas flow channel groove 12 is about 1 [mm], and the height Hb of the positioning projection 13 is about 5 [mm].

[0016] The positioning protrusions 13 have the following advantages. When two separators 10 are stacked, the positioning protrusions 13 on the upper and lower separators 10 accurately align the upper and lower separators 10 with each other. The height Hb of the positioning protrusions 13 is greater than the groove depth Da of the gas flow channel groove 12. Therefore, when two separators 10 are stacked, the positioning protrusions 13 make contact with each other before the gas flow channel groove 12. The positioning protrusions 13 of one separator 10 and the positioning protrusions 13 of the other separator 10 overlap, aligning the two separators 10 with each other. Since each separator 10 has positioning protrusions 13 in at least two places, the two separators 10 are accurately aligned with each other and overlap. If the positioning protrusions 13 are not present, the following disadvantages may occur. The substrate 11 is provided with a plurality of parallel gas flow channel grooves 12. If there are no positioning protrusions, the i-th gas flow channel groove of one separator 10 and the (i+1)th (or (i-1)th) gas flow channel groove of the other separator 10 may overlap. In other words, the two separators 10 may be misaligned and overlap. The positioning protrusions 13 can prevent such misalignment.

[0017] Furthermore, the positioning projection 13 has the advantage of making it easier for the lower separator 10 to separate from the upper separator 10 when the uppermost separator 10 of the stacked separators 10 is picked up. Figure 3(a) shows a cross-sectional view of two separators 10 stacked on top of each other. Figure 3(b) shows a cross-sectional view of conventional separators (separators 900 without positioning projections) stacked on top of each other. When there are no positioning projections, the gas flow channel groove 12 of the upper separator 900 and the gas flow channel groove 12 of the lower separator 900 come into contact. This creates a sealed space C sandwiched between the upper and lower gas flow channel grooves 12 (see Figure 3(b)). The air in the sealed space C makes it difficult for the upper and lower separators 900 to separate.

[0018] On the other hand, in the separator 10 of the embodiment, since the positioning protrusions 13 of the upper and lower separators 10 overlap, the thick plate portion 13b of the upper separator 10 also overlaps with the thick plate portion 13b of the lower separator 10 (the location indicated by the arrow A in Fig. 3(a)). The overlapping of the thick plate portions 13b of the upper and lower separators 10 ensures a gap between the gas flow path grooves 12 of the upper and lower separators 10 (the location indicated by the arrow B in Fig. 3(a)). Since the gas flow path grooves 12 of the upper and lower separators 10 do not contact each other, the sealed space C shown in Fig. 3(b) does not occur. Therefore, when the upper separator 10 is lifted, the lower separator 10 is likely to separate.

[0019] Furthermore, the positioning protrusion 13 is provided at the corner of the substrate 11. Since the substrate 11 of the separator 10 is a thin metal plate, it is easily deformed. As shown in Fig. 4, when the end of the substrate 11 of the upper separator 10 is lifted, first, the positioning protrusion '13 of the upper separator 10 separates from the lower separator 10. Air enters between the positioning protrusions 13 of the upper and lower separators 10, and it becomes easier for air to enter between the upper and lower gas flow path grooves 12. As a result, when the upper separator 10 is lifted, the lower separator 10 is even more likely to separate. The thick arrow line in Fig. 4 schematically represents the air flow.

[0020] As described above, the positioning protrusion 13 having the thick plate portion 13b can align the mutual exact positions when the upper and lower separators 10 are overlapped, and makes it easier for the lower separator 10 to separate when the upper separator 10 is lifted.

[0021] Fig. 5 shows a cross-sectional view of the separator 20 of the modification. The positioning protrusion 23 is different from the separator 10 of the embodiment in that it has a thick plate portion 23b at its top. Even if the thick plate portion 23b is provided at the top of the positioning protrusion 23, a gap B is ensured between the gas flow path grooves 12 of the upper and lower separators 10. Note that the arrow A in Fig. 5 indicates the location where the thick plate portions 23b of the upper and lower separators 20 are in contact.

[0022] In the separator 10 of the embodiment (see FIG. 2), a plurality of thick plate portions 13b may be provided on one positioning projection 13, or one thick plate portion 13b in the form of a convex strip may be provided so as to surround the slope of the positioning projection 13. In the separator 20 of the modified example, by providing the thick plate portion 23b at the top of the positioning projection 23, the size of the thick plate portion 23b can be made smaller than that of the thick plate portion 13b of the separator 10 of the embodiment.

[0023] Points to note regarding the technology described in the embodiment are described. In the separator 10 of the embodiment, the positioning projection 13 is circular when the substrate 11 is viewed in plan. The positioning projection may be an elongated convex strip. It is preferable that at least two positioning projections are provided on one separator. Each positioning projection is preferably provided at any one of the four corners of the rectangular separator. The positioning projection may be provided on either side of the separator.

[0024] As described above, specific examples of the present invention have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.And the technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in this specification or the drawings can achieve a plurality of purposes simultaneously, and achieving one of those purposes itself has technical utility.

Explanation of Reference Numerals

[0025] 10, 20: separator; 11: substrate; 12: gas flow path groove; 13, 23: positioning projection; 13b, 23b: thick plate portion; 900: separator (conventional example)

Claims

[Claim 1] It is a separator for fuel cells, A rectangular flat substrate, The substrate is provided with a plurality of parallel gas flow channel grooves, Positioning protrusions are provided at least two locations at the four corners of the substrate, the width of which is greater than the width of the gas flow channel groove and the height of which is greater than the depth of the gas flow channel groove, It is equipped with, The positioning projection is a separator having a hollow interior and a thick plate portion whose thickness is greater than the thickness of the substrate.

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