JP2008293728A - Gas passage composing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance water absorbing performance and gas fluidity in a gas passage composing member. <P>SOLUTION: The gas passage composing member 30 has two or more projecting parts 31 and through-holes 32. The gas passage composing members 30 are stacked so that the projecting parts 31 and the through-holes 32 in the upper and lower gas passage composing members 30 are overlapped in the same position. Height Dh1 of the projecting part 31 and diameter Dv1 of the through-hole 32 satisfy the relation of Dv1<Dh1. As a result, water covering the place between adjoined projecting parts 31, that is, covering the through-hole 32 is moved upward in the stacking direction by capillary action. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas flow path component that is used by being disposed in a gas flow path of a fuel cell.

  In a fuel cell, a gas flow path constituent member is arranged with respect to a gas flow path formed by a membrane electrode assembly (MEA) or a gas diffusion layer and a gas separator, thereby improving gas diffusion performance with respect to the membrane electrode assembly. Techniques for achieving this have been proposed. In such a technique, a metal fin processed into a porous body or a corrugated plate is used as a gas flow path component (for example, Patent Document 1 and Patent Document 2).

JP 2003-282098 A JP 2004-127666 A

  However, in the case of using a porous body, the generated water cannot be absorbed from the membrane electrode assembly or the gas diffusion layer unless the porous body diameter is reduced to the extent that capillary action is obtained. There is a problem that the gas pressure loss increases when the value is reduced. In addition, when fins are used, the water adhering to the fins is difficult to move if the fin interval is reduced, and the generated water cannot be absorbed from the membrane electrode assembly or the gas diffusion layer if the fin interval is increased. There is. Therefore, it is desired to achieve both suppression of increase in gas pressure loss and improvement of drainage performance of generated water.

  The present invention has been made to solve at least a part of the above-described conventional problems, and aims to improve both the water absorption performance and the gas flow performance in the gas flow path component.

  The present invention for solving at least a part of the above problems adopts the following aspects.

  The first aspect of the present invention provides a gas flow path forming member in which a plurality of substrates are laminated. In the gas flow path constituting member according to the first aspect of the present invention, the substrate has a plurality of protrusions having a predetermined height dimension and a plurality of through holes having a hole diameter smaller than the predetermined height dimension. And are laminated so that the through holes are aligned.

  According to the gas flow path constituting member according to the first aspect of the present invention, the gas flow path constituting member has a plurality of through holes having a hole diameter smaller than the predetermined height dimension of the projecting portion. And the gas flow performance can be improved.

  In the gas flow path forming member according to the first aspect of the present invention, the protruding portion and the through hole may be arranged with regularity. In this case, uniform water absorption performance and gas flow performance can be obtained in the entire region of the gas flow path component.

  In the gas flow path forming member according to the first aspect of the present invention, the protrusions are arranged at a first interval so as to form a plurality of rows in the gas flow direction, and the first interval is It may be smaller than the second interval which is the interval between the columns. In this case, the movement of the fluid existing between the projecting portions with respect to each row can be suppressed.

  In the gas flow path forming member according to the first aspect of the present invention, the through hole may be disposed between the protruding portions forming the rows. In this case, the fluid existing between the protrusions can be guided in the stacking direction.

  In the gas flow path forming member according to the first aspect of the present invention, the protrusions and the through holes in each row are arranged with a half-pitch shift with respect to the protrusions and the through holes in adjacent rows. May be. In this case, the coupling | bonding of the fluid which moves to a gas flow path formation member via a through-hole can be suppressed or prevented.

  A second aspect of the present invention provides a gas flow path forming member. The gas flow path component according to the second aspect of the present invention includes a plurality of substrates having a plurality of through-holes having a predetermined hole diameter, and a separation member that separates each of the substrates at an interval larger than the predetermined hole diameter dimension. With.

  According to the gas flow path constituting member according to the first aspect of the present invention, the gas flow path component member includes the plurality of through holes and the separation member that separates the substrates at intervals larger than the hole diameter of the plurality of through holes. It is possible to improve the water absorption performance in the path constituent member and improve the gas flow performance.

  In the gas flow path forming member according to the second aspect of the present invention, the through holes may be arranged with regularity. In this case, uniform water absorption performance and gas flow performance can be obtained in the entire region of the gas flow path component.

  Hereinafter, a gas flow path forming member according to the present invention will be described based on examples with reference to the drawings.

First embodiment:
The gas flow path component according to the first embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of a fuel cell including a gas flow path component according to the first embodiment. FIG. 2 is a plan view of a unit cell in the first embodiment.

  The fuel cell 100 in the present embodiment is formed by stacking a plurality of unit cells, which are the minimum constituent units. The unit cell includes a membrane electrode assembly 10, a gas diffusion layer 20, a gas flow path constituting member 30, a porous body 40, an anode gas separator 50a, and a cathode gas separator 50c. Between the anode gas separator 50a and the cathode gas separator 50c and the membrane electrode assembly 10 (gas diffusion layer 20), a fuel gas flow channel 60 in which the fuel gas flows and an oxidizing gas flow channel in which the oxidizing gas flows, respectively. 65 is partitioned. The fuel gas supplied from the external fuel gas source is introduced into the fuel gas channel 60 via the fuel gas supply manifold 80 shown in FIG. Of the fuel gas introduced into the fuel gas channel 60, the fuel gas that has not been subjected to the electrochemical reaction is discharged to the outside of the fuel cell 100 through the fuel gas discharge manifold 81 as a fuel off gas. The oxidizing gas supplied from the external oxidizing gas supply source is introduced into the oxidizing gas channel 65 through the oxidizing gas supply manifold 85. Of the oxidizing gas introduced into the oxidizing gas channel 65, the oxidizing gas that has not been subjected to the electrochemical reaction is discharged outside the fuel cell 100 through the oxidizing gas discharge manifold 886 as an oxidizing off gas. Further, the remaining openings in FIG. 2 may be used as a coolant supply manifold and a coolant discharge manifold used for circulating coolant for cooling the fuel cell 10. In FIG. 1, the fuel gas manifolds 80 and 81 and the oxidizing gas manifolds 85 and 86 are not shown in order to simplify the description.

  The membrane electrode assembly 10 is, for example, a layered body in which electrode catalysts are provided on both surfaces of a solid electrolyte membrane. In the present embodiment, the surface to which fuel gas is supplied in the membrane electrode assembly 10 is referred to as an anode, and the surface to which oxidizing gas is supplied is referred to as a cathode. For the solid electrolyte membrane 10, for example, a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin including perfluorocarbon sulfonic acid is used. As the electrode catalyst, a noble metal or a noble metal alloy such as platinum (Pt) or a platinum alloy is used.

  Gas diffusion layers 20 are respectively formed on both surfaces of the membrane electrode assembly 10. The gas diffusion layer 20 is a carbon porous member, and is formed of, for example, carbon cloth or carbon paper. The gas diffusion layer 20 has a function of improving the gas supply efficiency with respect to the electrode catalyst, enhancing the current collecting property between the gas flow paths 60 and 65 and the electrode catalyst, and protecting the electrolyte membrane. Note that the gas diffusion layer 20 may not be provided depending on the gas diffusibility and flow resistance of each gas flow channel 60, 65, and therefore, in this embodiment, the membrane electrode assembly 10 and the gas diffusion layer 20 are separated. However, a structure in which an electrolyte membrane having an electrode catalyst on its surface and a gas diffusion layer are integrated may be referred to as a membrane electrode assembly.

  The gas flow path component 30 is a metallic plate-like member that includes a plurality of protrusions 31 and a plurality of through holes 32. In this embodiment, the gas flow path component 30 generates the generated water by the electrochemical reaction or humidifies the oxidizing gas, so that the gas flow path on the cathode side where water is easily stored, that is, the oxidizing gas It is arranged in the flow path 65. Each protrusion 31 and each through-hole 32 are formed, for example, by applying press processing and etching processing to a metal plate-shaped material. According to these processes, there is an advantage that it is easy to control the shape and size of the protruding portion 31 and the through hole 32 and the thickness of the gas flow path component 30 and that the mass productivity is excellent. Each protrusion 31 and each through hole 32 are arranged with regularity, and the through hole 32 is formed between two adjacent protrusions 31. As is clear from FIG. 1, the two gas flow path component members 30 are laminated so that the protruding portion 31 of the lower gas flow path component member 301 overlaps the protruding portion 31 of the upper gas flow path component member 302. Has been.

  The porous body 40 is a member having a plurality of voids (holes). For example, a metal porous body such as a foam metal or a metal mesh is used. In the present embodiment, the porous body 40 is disposed in the gas flow path on the anode side, that is, the fuel gas flow path 60. The porous body 40 uniformly guides the fuel gas flowing through the fuel gas channel 60 to the gas diffusion layer 20.

  The anode gas separator 50a and the cathode gas separator 50c are separators disposed on the anode side and the cathode side of the membrane electrode assembly 10, respectively, and are made of conductive materials such as stainless steel or metal thin plates such as titanium or titanium alloy. It is a member. The anode gas separator 50a and the cathode gas separator 50c are arranged separately from the membrane electrode assembly 10 (diffusion layer 20), and as described above, the fuel gas channel 60 and the oxidizing gas channel 65 are partitioned. .

  The anode gas separator 50a and the cathode gas separator 50c may be, for example, gas separators arranged in pairs on the anode side and the cathode side, respectively, or one surface functions as an anode gas separator and the other surface A gas separator that functions as a cathode gas separator may be used. In the former case, the anode gas separator 50a and the cathode gas separator 50c, which are separate members, are disposed adjacent to each other. In this case, an introduction portion necessary for introducing gas from each manifold to each gas flow path 60, 65 is formed by arrangement of the seal portion, cutting, or the like. In the latter case, an integrated gas separator is formed by joining three plates: an anode side plate facing the anode, a cathode side plate facing the cathode, and an intermediate plate disposed between the plates. In this case, it is possible to easily form the introduction portion necessary for introducing the gas from each manifold to each gas flow path 60, 65 by pressing, etching, or the like.

  In this embodiment, it is only necessary to secure a predetermined volume space for disposing the gas flow path component 30 as at least the cathode gas flow path 65, and other specific configurations of the fuel cell 100 are arbitrary configurations. There may be.

  With reference to FIGS. 3-5, the detailed structure and effect | action of the gas flow path structural member 30 which concern on a present Example are demonstrated. FIG. 3 is an explanatory view showing the positional relationship between the protruding portion and the through hole in the gas flow path constituting member. FIG. 4 is a cross-sectional view showing a cross section of the unit battery shown in FIG. 2 cut along a cutting line 4-4. FIG. 5 is an explanatory view showing the movement state of water in the gas flow path constituting member according to the present embodiment.

  In the gas flow path constituting member 30 according to the present embodiment, as shown in FIG. 3, the protruding portions 31 are regularly arranged at a predetermined interval S1 to form a line. The through hole 32 is formed between adjacent protruding portions 31 in the same row. Each row formed by the protrusion 31 and the through hole 32, for example, the row L1 and the row L2, are separated by a predetermined interval S2. The inter-row portion 35 formed by each row functions as a flow path for the oxidizing gas. Note that the relationship of S1 <S2 is established, and the values of S1 and S2 are preferably 50 μm <S2 <2 mm, 10 μm <S1 <500 μm, for example.

  Since the relationship of S1 <S2 is established, the capillary action works, and the movement of the water W covering the through holes 32 to the inter-row portion 35 between the adjacent protruding portions 31 is suppressed or prevented. The interspace 35 is not easily blocked by water, or cannot be blocked. Therefore, the hindrance of the flow of the oxidizing gas caused by water can be suppressed or prevented.

  In the adjacent rows L1 and L2, the protruding portions 31 and the through holes 32 are formed so as to be shifted by a half pitch. On the other hand, as shown in FIG. 4, each gas flow path component member 30 includes each protrusion 31 and through-hole 32 in the lower gas flow path component member 30, and each gas flow path component member 30 in the upper gas flow path component member 30. The projecting portions 31 and the through holes 32 are laminated so as to have the same surface position.

  Each through hole 32 has a diameter Dv1. Each protrusion 31 has dimensions of height Dh1, major axis length Dv2, and minor axis length Dv3. A relationship of Dv1 <Dh1 is established between the diameter Dv1 of the through hole 32 and the height Dh1 of the protruding portion 31. As each dimension value, for example, 50 μm <Dh1, Dv2 <2 mm, 10 μm <Dv1, and Dv3 <500 μm are preferable. The thickness t of the gas flow path component 30 is desirably 50 μm <t <200 μm, for example.

  In general, it is known that the behavior of water in capillaries and pores having a capillary length (2 mm) or less can be considered by the representative diameter. In this embodiment, as shown in FIG. 3 and FIG. 5, the water W exists on the through hole 32 sandwiched between the upper and lower gas flow path constituting members 30, so the representative diameters are Dh1 and Dv1. . In order for the water W1 in contact with the gas diffusion layer 20 to move toward the cathode gas separator 50c by capillary action, a relationship of P1-P2> 0 may be established between the water-pressure near-water pressures P1 and P2. Required. The gas-liquid interface vicinity water pressure P is evaluated by P = P0−4ρ / D (Expression 1) when the water interface shape is concave, and P = P0 + 4ρ / D (Expression 2) when convex. Here, P0: gas pressure, ρ: surface tension coefficient of water, and D: pore diameter.

  When the gas flow path component 30 is not subjected to water repellent treatment, the shape of the gas-liquid interface of the water W1 is generally concave. Therefore, using the above formula 1, P1 = P0-4ρ / Dh1 , P2 = P0−4ρ / Dv1. P1−P2 = 4ρ ((1 / Dv1) − (1 / Dh1)). In this embodiment, since the relationship of Dv1 <Dh1 is established, P1−P2> 0. As a result, the water W1 moves toward the cathode gas separator 50c.

  Here, in the water W2 existing across the through hole 32 or the moving water W2, the gas-liquid interface shape in the vicinity of the through hole 32 may be convex. Also in this case, if the relationship P3-P4> 0 is established between the water pressure P3 near the gas-liquid interface of the convex portion and the water pressure P4 near the gas-liquid interface of the concave portion, the water W2 moves in the direction of the cathode gas separator 50c. Can be promoted. Using the above Equation 1 and Equation 2, the water-liquid interface vicinity water pressure of the water W2 is P3 = P0 + 4ρ / Dv1, P4 = P0-4ρ / Dh1, and P3-P4 = 4ρ ((1 / Dv1) + ( 1 / Dh1))> 0. Accordingly, the water W2 moves toward the cathode gas separator 50c.

  As described above, according to the gas flow path constituting member 30 according to the first embodiment, the relationship of the diameter Dv1 of the through hole 32 <the height Dh1 of the protruding portion 31 is established. The generated water generated by the electrochemical reaction in the electrode assembly 10 and absorbed by the gas diffusion layer 20 is moved to the cathode gas separator 50c side. In addition, since the through holes 32 are arranged at the same position in the gas flow path component 30, it becomes possible to facilitate the movement of water in the stacking direction, and the membrane electrode assembly 10 and the gas diffusion layer 20 Water can be quickly removed from As a result, it is possible to remove the water generated in the membrane electrode assembly 10 and the water absorbed in the gas diffusion layer 20, and suppress or prevent a decrease in gas diffusion performance caused by water absorption. Therefore, it is possible to suppress or prevent a decrease in power generation performance of the fuel cell 100.

  In addition, when the height Dh1 of the protruding portion 31 is increased to reduce the pressure loss of the gas flow path, the water is removed from the gas diffusion layer 20 and the membrane electrode assembly 10 as long as the relationship of Dv1 <Dh1 is maintained. Therefore, it is possible to suppress or prevent a decrease in gas diffusion performance due to water absorption and to suppress or prevent a decrease in power generation performance of the fuel cell 100.

  Further, in this embodiment, since the relationship of dimension S2 between rows 35 and dimension S1 between protrusions 31 is established, water can flow between the protrusions 31, that is, on the through holes 32 by capillary action. Fastened. Therefore, the inter-row portion 35 functioning as the oxidizing gas flow path 65 is not easily blocked by water, or is not blocked, and an increase in flow resistance (pressure loss) due to water can be suppressed or prevented. In addition, since water is retained on the through holes 32, the water moves to the upper layer and hardly moves to the inter-row portion 35. The water that has moved to the surface of the cathode gas separator 50c spreads in the surface of the cathode gas separator 50c to form a liquid film, and the length in the gas flow direction becomes longer. As a result, the drainage (water mobility) can be improved even when the pressure loss is low due to the gas differential pressure between the upstream side and the downstream side.

  In this embodiment, since the gas flow path component 30 is arranged so that the protruding portion 31 contacts the gas diffusion layer 20, the opening area with respect to the gas diffusion layer 20 is increased, and the gas flow from the gas diffusion layer 20 is increased. The movement of water to the path component 30 can be smoothed.

  In the present embodiment, since the gas flow path constituting member 30 having the same structure in which the protruding portions 31 and the through holes 32 are arranged in the same manner is used, cost reduction can be achieved. Moreover, since the protruding part 31 exists in the same position in each gas flow path structural member 30, compared with the case where the position of the protruding part 31 is arbitrary, load resistance and electroconductivity can be improved.

  In the present embodiment, the protrusions 31 and the through holes 32 are formed with a half pitch shift with respect to the protrusions 31 and the through holes 32 in adjacent rows, that is, are arranged in a staggered manner. Therefore, it is difficult for the water moving through the gas flow path component 30 to be combined with each other, and the inter-row portion 35 can be prevented or suppressed from being blocked with water. As a result, a decrease in gas fluidity can be suppressed or prevented.

  As the gas flow path constituting member 30 used in the present embodiment, for example, when the projecting portion 31 and the through hole 32 are formed by press working, it is possible to use SUS316, 317 series austenitic stainless steel. From the viewpoint of corrosion resistance and corrosion resistance. Furthermore, it is desirable to apply Au plating or carbon coating after press molding.

Second embodiment:
A gas flow path constituent member according to the second embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is an exploded perspective view of a fuel cell including a gas flow path component according to the second embodiment. FIG. 7 is a cross-sectional view of a fuel cell including the gas flow path constituting member according to the second embodiment, similar to FIG.

  In the fuel cell 100a in the second embodiment, the gas flow path component 30 is also provided on the anode side. In general, the generated water is generated on the cathode side with the electrochemical reaction, but the generated water may move to the anode side through the membrane electrode assembly 10. Therefore, the water present in the anode can be removed by disposing the gas flow path component 30 in the fuel gas flow path 60 on the anode side.

  In the first embodiment, three gas flow path component members 30 are stacked and used. However, in the second embodiment, two gas flow path component members 30 are stacked and used. That is, the effect demonstrated in the 1st Example can be acquired by using two or more gas flow path components.

Other examples:
(1) In each of the embodiments described above, the protruding portion 31 is formed integrally with the gas flow path constituting member 30, but the gas flow path constituting member having the through hole 32 and the columnar member are separate. May be. Here, the columnar member functions as a separation member that defines the separation distance between the gas flow path constituting members to be a predetermined distance, and the thickness (height) Dh2 of the columnar member and the diameter Dv1 of the through hole 32 The relationship of Dv1 <Dh2 is established. The columnar member is joined to the gas flow path constituting member by brazing, for example.

(2) In each of the above embodiments, the gas flow path component 30 is arranged so that the protruding portion 31 contacts the gas diffusion layer 20, but the gas flow path such that the through hole 32 contacts the gas diffusion layer 20. The structural member 30 may be disposed.

(3) In each of the above embodiments, the elliptical columnar protrusion 31 is used, but a cylindrical or rectangular columnar protrusion may be used. Moreover, although the circular hole is used as the through-hole 32, an elliptical hole or a rectangular hole may be used. In any case, if the relationship of the height Dh> the hole diameter Dv of the protruding portion is established, the effects described in the above embodiments can be obtained.

(4) In each of the above embodiments, the individual gas flow path component members 30 to be stacked are referred to as gas flow path component members, but the stacked gas flow path component members are referred to as gas flow path component members. But it ’s okay.

(5) In each of the above embodiments, the protruding portions 31 and the through holes 32 forming each row are arranged with a half-pitch shift, but the protruding portions 31 and the through holes 32 forming each row are arranged at the same pitch. May be. Further, the protruding portion 31 and the through hole 32 may be arranged at arbitrary positions as long as the upper and lower through holes 32 are located at the same position. Further, the through holes 32 may be arranged at a place other than between the protruding portions 31 forming the row. In any case, an effect equivalent to the effect in the above embodiment can be obtained.

(6) In each of the above embodiments, the plate-like gas flow path constituting member 30 is used in a stacked manner, but a porous body in which the relationship of the height Dh of the protruding portion (column portion)> the hole diameter Dv is established. By doing so, an integrated gas flow path component may be realized. Even in the case of a porous body, as long as the relationship of the height Dh of the projecting portion (column portion)> the hole diameter Dv is established, an effect equivalent to the effect in the above embodiment can be obtained.

  As mentioned above, although this invention was demonstrated based on the Example and the modification, Embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention.

It is a disassembled perspective view of a fuel cell provided with the gas flow path structural member which concerns on a 1st Example. It is a top view of the unit cell in a 1st Example. It is explanatory drawing which shows the positional relationship of the protruding part and through-hole in a gas flow path component. It is sectional drawing which shows the cross section which cut | disconnected the unit battery shown in FIG. 2 by 4-4 cutting lines. It is explanatory drawing which shows the movement state of the water in the gas flow-path structural member which concerns on a 1st Example. It is a disassembled perspective view of a fuel cell provided with the gas flow-path structural member which concerns on a 2nd Example. It is sectional drawing of a fuel cell provided with the gas flow-path structural member which concerns on a 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 100a ... Fuel cell 10 ... Membrane electrode assembly 20 ... Gas diffusion layer 30 ... Gas flow path component 31 ... Projection part 32 ... Through-hole 40 ... Porous body 50a ... Anode gas separator 50c ... Cathode gas separator 60 ... Fuel Gas passage 65 ... Oxidizing gas passage 80 ... Fuel gas supply manifold 81 ... Fuel gas discharge manifold 85 ... Oxidation gas supply manifold 86 ... Oxidation gas discharge manifold

Claims (7)

A gas flow path forming member formed by laminating a plurality of substrates,
The substrate is
A plurality of protrusions having a predetermined height dimension;
A plurality of through holes having a hole diameter smaller than the predetermined height dimension,
A gas flow path forming member laminated so that the through holes are aligned. The gas flow path forming member according to claim 1,
The protruding portion and the through hole are gas flow path forming members arranged with regularity. The gas flow path forming member according to claim 2,
The protrusions are arranged at a first interval so as to form a plurality of rows in the gas flow direction,
The gas flow path forming member, wherein the first interval is smaller than a second interval that is an interval between the rows. In the gas flow path forming member according to claim 3,
The through-hole is a gas flow path forming member disposed between the protruding portions forming the rows. The gas flow path forming member according to claim 4,
The gas flow path forming member in which the protruding portion and the through hole in each row are arranged with a half-pitch shift with respect to the protruding portion and the through hole in the adjacent row. A gas flow path forming member,
A plurality of substrates having a plurality of through-holes having a predetermined hole diameter;
A gas flow path forming member provided with a separation member that separates the substrates at intervals larger than the predetermined hole diameter. The gas flow path forming member according to claim 6,
The said through-hole is a gas flow path formation member arrange | positioned with regularity.

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