JP2007242511A - Fuel cell - Google Patents

Abstract

An object of the present invention is to improve the seal life by increasing the height of a compression seal as much as possible without increasing the cell pitch of a fuel cell.
A gap portion is formed between a seal region of a gas manifold hole of a separator and a gas manifold hole of a membrane electrode assembly and communicates with an in-cell gas flow path. The gap portion is formed so that the inner diameter portion 31i of the gas manifold hole is positioned outside the seal region outer diameter portion 27p, and is formed as a radial gap between the inner diameter portion and the outer diameter portion. .
[Selection] Figure 5

Description

  The present invention relates to a fuel cell, and more particularly to improvement of a seal structure in the cell.

  The fuel cell fluid is generally one in which three fluids of fuel gas, oxidizing gas, and cooling water flow. The power generation operation is performed after all these seals are performed, but there are various methods for sealing each fluid. For example, Patent Document 1 discloses a cell structure in which cooling water in a reaction region in a cell is sealed with a compression seal, and fuel gas and oxidizing gas are sealed with an adhesive seal.

In this type of fuel cell, in consideration of maintainability, a compression seal is used for each removable unit so that it can be removed at the component level constituting a single cell or at a single cell or several cell level. The amount of sag determines the seal life. That is, the seal life can be increased as the seal height is secured and the compression allowance is increased.
JP 2003-77499 A

  However, in Patent Document 1, the gas from the manifold is introduced into the reaction region in the cell through the flow path formed in the resin frame, so that the flow path height of the gas introduction portion is increased. It is necessary to use a thick resin frame. In such a configuration, as a result, the height of the compression seal is reduced, which is not necessarily sufficient from the viewpoint of extending the life.

  On the other hand, there is a limit due to dimensional restrictions even if the seal height is increased. In particular, in a fuel cell for a moving body such as a vehicle, unlike a stationary fuel cell, there are large space restrictions for loading on a vehicle, securing utility space, etc., and increasing the output density as much as possible. Since there is a demand, downsizing of cell components is an important issue. Since the fuel cell stack is configured by stacking a large number of units such as tens to hundreds of cells depending on the required output, the thickness of each cell needs to be as small as possible. The lifetime will be limited.

  The present invention has been made paying attention to such conventional problems, and aims to make the height of the compression seal as large as possible without increasing the size of the fuel cell.

  The present invention includes a membrane electrode assembly, and a first separator and a second separator that are joined to both surfaces of the membrane electrode assembly to form a gas flow path in a cell through which fuel gas or oxidant gas flows. This is a fuel cell in which a large number of unit cells are stacked to form a stack.

  The fuel cell includes an in-cell cooling water passage through which cooling water flows between a first separator and a second separator of unit cells adjacent to each other in a stacked state, and a membrane electrode assembly and each separator. Between the first separator and the second separator, the manifold hole for gas communicating with the gas flow path through the stacking direction and the manifold hole for cooling water communicating with the cooling water flow path in the cell. A compression seal that seals the outer periphery of the cooling water flow path and the periphery of the manifold hole for gas is interposed.

  In the present invention, a gap communicating with the gas flow path in the cell is formed between the seal region of the gas manifold hole of the separator and the gas manifold hole of the membrane electrode assembly, and this gap is formed in the membrane. An inner diameter portion of the gas manifold hole of the electrode assembly is formed so as to be positioned outside an outer diameter portion of the seal region of the gas manifold hole of the separator, and a radial direction between the inner diameter portion and the outer diameter portion is formed. The gap is formed as a gap, or the gap is formed so that a part of the membrane electrode assembly is thin with respect to the seal region of the gas manifold hole of the separator, and the gap between the thin portion and the seal region is formed. It is formed as a gap in the stacking direction.

  According to the present invention, the gas flowing into the gas manifold hole is passed through the gap provided between the seal region of the gas manifold hole of the separator and the gas manifold hole of the membrane electrode assembly. The gas can be supplied to the flow path, or the gas from the in-cell gas flow path can be discharged to the gas manifold. In such a configuration, since the seal region of the gas manifold hole does not become an obstacle to gas flow, the height of the seal region, that is, the height of the compression seal is set to the compression seal that seals the outer peripheral portion of the cooling water flow path. Therefore, an improvement in the seal life can be realized without increasing the cell pitch.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 5 show a first embodiment of the present invention. In the figure, 10 and 20 are metal separators, 30 is a membrane electrode assembly (hereinafter referred to as “MEA”), and the unit cell of the fuel cell has the first separator 10 and the second separator on both sides of the MEA 30. These separators 20 are joined together. A fuel cell stack is configured by stacking a large number of these unit cells so that the required power can be obtained.

  FIG. 1 shows the surface of the first separator on the side where the fuel gas is introduced, and FIG. 2 shows the surface on the side where the cooling water is introduced. As shown in the drawing, the outer shape is substantially rectangular, and a gas manifold hole 11a, a cooling water manifold hole 12a, and a gas manifold hole 13a through which fuel gas, cooling water, and oxidant gas circulate are arranged at one end in the longitudinal direction. The manifold hole 11b for fuel gas, the manifold hole 12b for cooling water, and the manifold hole 13b for oxidant gas are also opened at the other end. Of the combinations of manifold holes, one through which the same fluid flows is the inlet and the other is the outlet.

  In FIG. 1, the manifold hole 11a is an inlet for fuel gas, and the manifold hole 11b is an outlet, and the region between them is a portion facing the reaction region 36 (see FIG. 3) on the fuel electrode side of the MEA 30. An internal gas flow path 14 composed of a large number of passage portions for distributing gas evenly to the reaction region is formed. However, the detailed configuration of the gas flow path 14 is omitted from the drawings.

  A thick line portion denoted by reference numeral 15 in FIG. 1 indicates a joint seal portion with the MEA 30 and surrounds the manifold holes 11a to 13a, 11b to 13b and the entire internal gas flow path 14 as shown in the figure, and fuel. The manifold holes 12a, 12b, 13a, 13b other than those for gas are provided so as to individually surround them. A gas flow path for fuel gas is defined between the joining surfaces of the separator 10 and the MEA 30 by joining the separator 10 to the resin film portion that is the base material of the MEA 30 along the joining seal portion 15, for example. In addition, the leakage of the fuel gas to the outside of the separator or the mutual leakage between the cooling water and the oxidant gas is sealed.

  The second separator 20 bonded to the opposite surface of the MEA 30, that is, the surface on the oxygen electrode side, also has a structure of the bonded seal portion, and the manifold holes (13 a, 13 b) for the oxidant gas are used for the oxidant gas. The first separator 10 is formed except that it is formed so as to communicate with each other through the internal gas flow path. The MEA 30 has manifold holes 31a to 33a and 31b to 33b at positions corresponding to the manifold holes 11a to 13a and 11b to 13b of the separator 10 or 20.

  As described above, the unit cell is formed by joining the two separators 10 and 20 on both sides of the MEA 30 and stacking a large number of these to form a stack. In the state in which the stack is configured, the manifold holes of each unit cell form a series of internal manifolds in the stacking direction, and exhibit a function of evenly distributing fluid such as fuel gas and cooling water to each unit cell.

  Next, the configuration of the in-cell flow path for cooling water and its seal structure will be described with reference to FIG. 2 or FIG. When the unit cells are stacked as described above, the cooling water flow path is defined between the first separator 10 and the second separator 20 of another adjacent unit cell. That is, a flow path for cooling water is defined between the second separator 20 of another unit cell located on the back side of the separator 10 shown in FIG.

  For this purpose, the back surface side of the separator 10 is formed so that the manifolds 12a and 12b for cooling water are connected via an intermediate in-cell cooling water flow path 24 as shown in FIG. The detailed configuration of the in-cell cooling water flow path 24 is not shown in the drawings.

  In FIG. 2, a broken line indicates a seal portion between other adjacent separators (in this case, the second separator). As shown in the drawing, each manifold hole and the entire in-cell flow path are shown. The first seal portion 25 that surrounds and the second seal portion 26 that surrounds only the periphery of the manifold holes 11a, 11b, 13a, and 13b for fuel gas or oxidant gas. The seal portions 25 and 26 are formed so as to protrude toward the MEA 20 as compared with the periphery of the cooling water manifold holes 12a and 12b and the portion of the in-cell cooling water flow path 24 (see FIG. 5). The protrusion height is approximately one half of the height of the compression seal described later in the compressed state. Hereinafter, a protruding portion of the seal portion 26 around the gas manifold hole is referred to as a seal region 27.

  FIG. 5 is a diagram illustrating a structure in which compression seals 42 and 43 made of a highly elastic material such as synthetic rubber are interposed between the first separator 10 of the unit cell and the second separator 20 of another adjacent unit cell. Shows the state. The compression seal 42 has a size that fits the first seal portion 25 that surrounds the entire cooling water flow path portion, and the compression seal 43 has a size that fits the second seal portion 26 that surrounds the manifold hole for gas. An annular sealing material processed into These compression seals 42 and 43 are provided by, for example, injection molding or vulcanization bonding along the seal portions (25, 26) of the second separator.

  FIG. 5 shows the characteristic configuration of the present invention, that is, the gas manifold hole 31a (or 31b, 33a, 33b; the same applies hereinafter) formed in the MEA 30 has an opening area larger than that of the separator 10, More specifically, the inner diameter portion 31i is formed to be larger than the outer diameter portion 27p of the seal region 27 around the gas manifold 11a, and the inner diameter portion 31i is radially formed between the inner diameter portion 31i and the outer diameter portion 27p. A gap 28 is provided.

  The operational effects based on the above configuration will be described with reference to FIGS. Generally, when a cell is configured by laminating a separator and an MEA having a resin film portion, the dimensions and shapes of the manifold holes are substantially the same. In such a configuration, if the height of the seal region 27 around the manifold hole, that is, the height of the compression seal 43 is to be secured to the same level as the compression seal 42 on the other outer peripheral side, the fuel as shown in FIG. The inner region of the gas manifold hole 11a is in contact with the seal region 27 and the communication with the in-cell flow path 14 is cut off, so that the fuel gas cannot be supplied. For this reason, conventionally, the seal height in the portion corresponding to the seal area 27 is lowered to secure a flow path between the seal area 27 and the MEA 30. As a result, the seal height in the seal area is lowered and the seal life is shortened. It was.

  On the other hand, according to the configuration of the present embodiment, as shown in FIG. 5, the gas is supplied via the gap 28 provided between the seal region 27 of the separator 10 and the gas manifold hole 31 a of the MEA 30. The gas flowing into the manifold hole 31a can be supplied to the gas flow path 14 in the cell as indicated by an arrow, or the gas from the in-cell gas flow path 14 can be discharged to the gas manifold (31b). In such a configuration, since the seal region 27 of the gas manifold hole 11a does not become an obstacle to gas flow, the height of the seal region, that is, the height of the compression seal 43 is set to the outer periphery of the cooling water channel 24. It can be equal to or better than the compression seal 42 to be stopped, and therefore the seal life can be improved without increasing the cell pitch.

  Next, another embodiment of the present invention will be described. In each embodiment, parts corresponding to those in the drawings will be described with the same reference numerals.

  FIG. 6 shows a second embodiment of the present invention. This is because the seal area 27 does not interfere with the gas manifold hole 31a of the MEA 30 as described above, and the height of the seal flow area 27 is higher than the thickness of the MEA 30 as shown in the drawing. Thus, the life of the compression seal 43 can be further improved accordingly.

  FIG. 7 shows a third embodiment of the present invention. This is provided with a rib-like support member 29 having a height substantially equal to the thickness of the MEA 30 in the seal region 27 facing the manifold hole 31a of the MEA 30 and made of a material having a higher level than the compression seal 43. Is. In the configuration as shown in FIG. 5 where the upper surface of the seal region 27 is a space, the seal region 27 may be deformed by the reaction force from the compression seal 43 depending on the rigidity of the separator 10 or 20, and the seal performance may be impaired. Arise. On the other hand, according to the present embodiment, the sealing reaction force is supported between the adjacent separators 10 and 20 by the support member 29, so that the separators 10 and 20 can be prevented from being deformed and have good sealing performance. Can be secured.

  FIG. 8 shows a fourth embodiment of the present invention. In this case, the gas manifold hole 31a of the MEA 30 is expanded only at the edge on the gas flow path 14 side in the cell, and the gap 28 is provided only on the flow path 14 side. There is no need for gas supply in the area other than the flow path 14 side of the manifold hole 31a, and it is possible to sufficiently supply the gas flow path 14 with such a configuration. In addition, by doing this, it is possible to limit the portion that is not supported by the MEA 30 when the reaction force of the compression seal 43 acts on the seal region 27, and to minimize the deformation of the separator 10 or 20 described above.

  FIG. 9 shows a fifth embodiment of the present invention. This is provided with a folded portion 44 in a form in which the opening edge portion of the gas manifold hole 11a (21a) of the separator 10 (20) is folded outward. Since the rigidity of the separator 10 or 20 around the manifold hole is improved by the folded portion 44, the deformation due to the reaction force of the compression seal 43 can be suppressed and good sealing performance can be exhibited.

  FIG. 10 shows a sixth embodiment of the present invention. This is because a part of the MEA 30 is processed to be thin at a portion facing the seal region 27 of the separator 10, and a gap 28 is formed as a gap in the stacking direction between the thin portion 45 and the seal region 27. is there. When the resin film constituting the MEA 30 has a multi-layer structure, the thin portion 45 may be formed by removing a part of the layer from the portion facing the seal region 27. In this embodiment, a communication path from the manifold hole 31 a to the internal gas flow path 14 is secured between the thin portion 45 and the seal region 27. In this embodiment, since the thin portion 45 is opposed to the seal region 27, the height of the seal region 27, that is, the height 43 of the compression seal is accordingly restricted, so that the seal life is shorter than that of the other embodiments. Although slightly shortened, the resin film portion constituting the MEA 30 is interposed between the seal region 27 and another separator facing the seal region 27, which is advantageous in terms of insulation performance.

The top view of the separator which concerns on the 1st Embodiment of this invention. Similarly the back view of a separator. The top view of MEA (membrane electrode assembly) similarly. The principal part sectional drawing which showed the reference structural example of the part along the AA of FIG. FIG. 2 is an essential part cross-sectional view along the line AA in FIG. 1. The principal part sectional view equivalent to FIG. 5 of the 2nd Embodiment of this invention. The principal part sectional view equivalent to FIG. 5 of the 3rd Embodiment of this invention. The principal part sectional drawing equivalent to FIG. 5 of the 4th Embodiment of this invention. The principal part sectional view equivalent to FIG. 5 of the 5th Embodiment of this invention. The principal part sectional view equivalent to FIG. 5 of the 6th Embodiment of this invention.

Explanation of symbols

10, 20 Separator 11a, 11b, 31a, 31b Manifold hole for fuel gas 12a, 12b, 32a, 32b Manifold hole for cooling water 13a, 13b, 33a, 33b Manifold hole for oxidizing gas 14 In-cell gas flow path 24 In cell Cooling water flow paths 25, 26 Seal part 27 Seal area 28 Gap part 29 Support member 30 Membrane electrode assembly (MEA)
36 Reaction regions 42, 43 Compression seal 44 Folding part

Claims (6)

A unit cell including a membrane electrode assembly and a first separator and a second separator that are bonded to both surfaces of the membrane electrode assembly to form an in-cell gas flow path through which fuel gas or oxidant gas flows. A fuel cell in which a stack is formed by stacking many,
An in-cell cooling water flow path is provided between the first separator and the second separator of the unit cells adjacent to each other in the stacked state, and the membrane electrode assembly and each separator penetrate in the stacking direction. A manifold hole for gas communicating with the gas flow path and a manifold hole for cooling water communicating with the in-cell cooling water flow path,
In the fuel cell including a compression seal that seals the outer periphery of the cooling water passage and the periphery of the manifold hole for gas between the first separator and the second separator,
Between the seal region of the gas manifold hole of the separator and the gas manifold hole of the membrane electrode assembly, a gap portion communicating with the gas flow path in the cell is formed,
The gap portion is formed such that the inner diameter portion of the gas manifold hole of the membrane electrode assembly is located outside the seal region outer diameter portion of the gas manifold hole of the separator, and the inner diameter portion and the outer diameter portion A fuel cell characterized in that it is formed as a radial gap between the two. A unit cell including a membrane electrode assembly and a first separator and a second separator that are bonded to both surfaces of the membrane electrode assembly to form an in-cell gas flow path through which fuel gas or oxidant gas flows. A fuel cell in which a stack is formed by stacking many,
An in-cell cooling water passage is provided between the first separator and the second separator of the unit cells adjacent to each other in the stacked state, and the membrane electrode assembly and each separator penetrate in the stacking direction. A gas manifold hole communicating with the gas flow path and a cooling water manifold hole communicating with the in-cell cooling water flow path,
In the fuel cell including a compression seal that seals the outer periphery of the cooling water passage and the periphery of the manifold hole for gas between the first separator and the second separator,
Between the seal region of the gas manifold hole of the separator and the gas manifold hole of the membrane electrode assembly, a gap portion communicating with the gas flow path in the cell is formed,
The gap portion is formed as a gap in the stacking direction between the thin wall portion and the seal region by forming a part of the membrane electrode assembly thinly in a portion facing the seal region of the gas manifold hole of the separator. The fuel cell characterized by the above-mentioned.   2. The fuel cell according to claim 1, wherein the height of the seal region of the gas manifold hole of the separator facing the manifold hole of the membrane electrode assembly is set higher within a range smaller than the thickness of the membrane electrode assembly.   The seal region of the gas manifold hole of the separator facing the manifold hole of the membrane electrode assembly has a height substantially equal to the thickness of the membrane electrode assembly, and is made of a material having a high level compared to the compression seal. The fuel cell according to claim 1, further comprising a support member.   3. The fuel cell according to claim 1, wherein the gap is provided only at an edge of the gas manifold hole on the gas flow path side in the cell.   3. The fuel cell according to claim 1, wherein the gas manifold hole of the separator has a folded portion in which an opening edge portion is folded outward. 4.