JP2018055788A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack capable of efficiently discharging residual water from a gas passage to a manifold.SOLUTION: A fuel cell stack includes a plurality of cell units stacked therein, each cell unit including a membrane electrode assembly 1, a first separator 3 disposed on a lower side of the membrane electrode assembly 1, and a second separator 5 disposed on an upper side of the membrane electrode assembly 1. A fuel gas outflow passage 53 is a hydrophobic region continuous passage where a hydrophobic region 55 is continuously connected over the total length of the fuel gas outflow passage 53 (gas passage) while both of the hydrophobic region 55 and a hydrophilic region 57 are formed to the inner surface of the fuel gas outflow passage 53 (gas passage).SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel cell stack.

  Conventionally, in a fuel cell stack, a structure in which fuel gas flowing through a fuel gas flow path is discharged to a manifold is known (see Patent Document 1).

  The anode-side separator in Patent Document 1 includes a hydrogen channel, an outlet buffer unit into which anode off-gas flows through the hydrogen channel, and an anode off-gas outlet channel disposed on the manifold side of the outlet buffer unit. I have. The anode off gas flowing out from the hydrogen flow path is discharged from the outlet buffer portion to the manifold via the anode off gas outlet flow path.

JP2013-118125A

  However, in Patent Document 1, hydrophilic processing is performed on the outlet buffer portion, and water repellency processing is performed on the anode off-gas outlet flow path. Therefore, there is a problem that the residual water mixed in the anode off gas is likely to be accumulated in the anode off gas outlet passage having water repellency.

  Therefore, an object of the present invention is to provide a fuel cell stack capable of efficiently discharging residual water from a gas flow path to a manifold.

  The fuel cell stack according to the present invention is configured by laminating a plurality of cell units including a membrane electrode assembly, a first separator, and a second separator. A water repellent region continuous passage in which the water repellent region is continuously connected over the entire length of the gas passage is provided.

  According to the fuel cell stack of the present invention, the residual water mixed in the gas can be efficiently discharged from the gas passage to the manifold.

FIG. 1 is an exploded perspective view of a cell unit constituting the fuel cell stack according to the first embodiment of the present invention. 2, (a) is a rear view showing the back surface of the first separator constituting the cell unit, (b) is a cross-sectional view taken along line AA in (a), and (c) is B- in (a). It is sectional drawing by a B line. 3, (a) is a rear view showing the back surface of the second separator constituting the cell unit, (b) is a sectional view taken along the line CC in (a), and (c) is a sectional view taken along line D- in (a). It is sectional drawing by D line. FIG. 4 is a cross-sectional view showing a pair of cell units adjacent in the vertical direction, and corresponds to FIGS. 2B and 3B. FIG. 5 is a cross-sectional view showing a pair of cell units adjacent in the vertical direction, and corresponds to FIG. 2 (c) and FIG. 3 (c). FIG. 6 is a perspective view, partly in section, showing the main part in a state where the membrane electrode assembly, the first separator, and the second separator in FIG. 1 are assembled. FIG. 7 is an enlarged view of the fuel gas outflow passage in FIG. FIG. 8 is a schematic view according to the first embodiment showing a hydrophilic region and a water repellent region in FIG. 7. FIG. 9 is a schematic view according to the second embodiment showing the hydrophilic region and the water repellent region in FIG. FIG. 10 is a schematic view according to the third embodiment showing the hydrophilic region and the water repellent region in FIG. FIG. 11 is an enlarged view of the fuel gas outflow passage according to the second embodiment, and corresponds to FIG. FIG. 12 is a schematic view showing a hydrophilic region and a water-repellent region in FIG. FIG. 13 is an enlarged view of the fuel gas outflow passage according to the third embodiment, and corresponds to FIGS. 7 and 11. FIG. 14 is a schematic diagram according to the first embodiment showing the hydrophilic region and the water repellent region in FIG. 13. FIG. 15 is a schematic view according to the second embodiment showing the hydrophilic region and the water repellent region in FIG. 13. FIG. 16 is an enlarged view of the fuel gas outflow passage according to the fourth embodiment, and corresponds to FIGS. 7, 11, and 13. FIG. 17 is a schematic diagram showing a hydrophilic region and a water-repellent region in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawing, the upper side (vertically upward) of the stack direction of the fuel cell stack is the P direction, the lower side (vertically downward) is the Q direction, the horizontal direction is the R direction, the short direction of the cell unit is the X direction, and the longitudinal direction is the longitudinal direction. The Y direction is assumed.

[First embodiment]
First, the fuel cell stack according to the first embodiment will be described with reference to FIGS.

  In the fuel cell stack according to the first embodiment, cell units are stacked in a plurality of stages along the vertical direction.

  One cell unit is disposed on the membrane electrode assembly 1, the first separator 3 disposed on the lower side (Q direction) of the membrane electrode assembly 1, and on the upper side (P direction) of the membrane electrode assembly 1. And a second separator 5. The membrane electrode assembly 1, the first separator 3, and the second separator 5 are formed in a rectangular shape in a plan view extending along the R direction which is a horizontal direction, and in the drawing, a central portion in the longitudinal direction (Y direction) Shows up. The number of cell units constituting one fuel cell stack is not limited.

  The membrane electrode assembly 1 is also referred to as MEA (Membrane Electrode Assembly), and a reaction surface 7 is formed at the center in the Y direction, which is the longitudinal direction. The reaction surface 7 includes an electrolyte membrane made of, for example, a solid polymer and a pair of electrodes that sandwich the electrolyte membrane. As shown in FIGS. 1, 4, and 5, the fuel gas manifold 9, the cooling medium manifold 11, and the oxidizing gas manifold are disposed at the end in the Y direction of the membrane electrode assembly 1 along the X direction, which is the short direction. Manifolds 13 are in parallel. A sealing material 15 having a circular cross section is routed on the upper and lower surfaces of the membrane electrode assembly 1.

  As shown in FIGS. 1, 2, 4, and 5, the first separator 3 is assembled to the lower side of the membrane electrode assembly 1, so that the first separator 3 is formed in a space defined by the membrane electrode assembly 1 and the first separator 3. An oxidizing gas (for example, oxygen) is configured to flow. At the end of the first separator 3 in the Y direction, a fuel gas manifold 17, a cooling medium manifold 19, and an oxidizing gas manifold 21 are arranged in parallel along the X direction, which is the short direction. On the back side of the first separator 3, a plurality of cooling medium flow paths 23 extending along the Y direction are formed at the center in the Y direction, which is the longitudinal direction. A flat convex surface 25 is formed so as to bulge above the general surface 26 (P direction) at the peripheral portion on the center side in the Y direction among the peripheral portions of the fuel gas manifold 17. A thin sheet-like sealing material 27 is routed on the outer peripheral portions of the upper surface and the lower surface of the first separator 3.

  As shown in FIGS. 1, 3, 4, and 5, the second separator 5 is combined on the upper side of the membrane electrode assembly 1, so that fuel is formed in a space defined by the membrane electrode assembly 1 and the second separator 5. A gas (for example, hydrogen) is configured to flow. At the end of the second separator 5 in the Y direction, a fuel gas manifold 31, a cooling medium manifold 33, and an oxidizing gas manifold 35 are arranged in parallel along the X direction, which is the short direction. In addition, a plurality of fuel gas flow paths 37 extending along the Y direction are formed at the center in the Y direction, which is the longitudinal direction. On the Y direction side of the fuel gas passage 37, a fuel gas discharge passage 39 and a convex portion 41 extending along the Y direction are formed. Between the fuel gas discharge passage 39 and the fuel gas manifold 9, a gas discharge hole 43 extending in the X direction is formed in the second separator 5. Of the peripheral edge of the fuel gas manifold 31, the gas discharge hole 43 extends in the Y direction. A wavy portion 45 is formed at the peripheral edge on the center side. As shown in FIGS. 1, 6, and 7, the corrugated portion 45 extends in a corrugated shape that undulates vertically as it goes in the X direction, and specifically includes a curved bottom portion 47 and a top portion 49. The bottom 47 is disposed at the same height as the general surface 51 of the second separator 5, and the top 49 is in contact with the back side of the convex surface 25 of the first separator 3. Further, the wavy portion 45 extends along the Y direction, and the extending length is set to L. That is, any cross section of the extended length L is formed as shown in FIG. As shown in FIGS. 6 and 7, a fuel gas outflow passage (gas passage, water repellent region continuous passage) 53 having a closed cross section is defined by the convex surface 25 of the first separator 3 and the corrugated portion 45 of the second separator 5. It is made. The fuel gas outflow passage 53 (water repellent region continuous passage) communicates with the fuel gas manifolds 9, 17, 31 (manifold) in the cell unit.

  Next, the flow of fuel gas will be briefly described.

  The fuel gas that has passed through the reaction surface 7 shown in FIG. 1 contains water vapor, and flows in the Y direction along the fuel gas discharge passage 39 as shown by the arrow in FIG. After flowing in the (P direction) and passing through the fuel gas outflow passage 53, it flows into the fuel gas manifold 9.

  Next, the first mode of the hydrophilic region and the water-repellent region on the inner surface of the fuel gas outflow passage 53 will be described with reference to FIGS. In the drawing, the water-repellent region 55 is indicated by a thick solid line, and the hydrophilic region 57 is indicated by a thin one-dot chain line. The water repellent region 55 can be formed by various methods such as applying a water repellent to the surface of the separator, performing plasma treatment or UV treatment, or performing sandblast treatment.

  As shown in FIG. 8, in the first mode, the water-repellent region 55 is formed on the upper surface of the bottom 47 of the wavy portion 45 of the second separator 5. The water-repellent region 55 has a U-shaped cross section and is formed over the entire length L of the corrugated portion 45 shown in FIG. Other portions on the inner surface of the fuel gas outflow passage 53 are formed in the hydrophilic region 57.

  As shown in FIG. 9, a plurality of fuel gas outflow passages 53 having a closed cross section are provided along the X direction. In the second mode, the water-repellent region 55 is formed on the entire upper surface of the corrugated portion 45 of the second separator 5 in the fuel gas outflow passage 53 one by one along the X direction. That is, in the fuel gas outflow passage 53 having a predetermined closed cross section, the water repellent region 55 is formed on the entire upper surface of the corrugated portion 45 of the second separator 5, and the hydrophilic region 57 is formed on the back side of the convex surface 25 of the first separator 3. Is formed. In the X direction, the inner surface of the fuel gas outflow passage 53 adjacent to the predetermined fuel gas outflow passage 53 forms a hydrophilic region 57 on the entire surface, and does not form a water repellent region 55 at all. The water repellent region 55 is formed over the entire length L of the corrugated portion 45 shown in FIG.

  As shown in FIG. 10, in the third mode, a water repellent region 55 is formed on the entire back surface of the convex surface 25 of the first separator 3. And the hydrophilic area | region 57 is formed in the whole upper surface of the wavelike part 45 of the 2nd separator 5. FIG. The water repellent region 55 is formed over the entire length L of the corrugated portion 45 shown in FIG.

  Below, the effect by 1st Embodiment is demonstrated.

(1) The membrane electrode assembly 1, the first separator 3 disposed on the lower side (front surface side) of the membrane electrode assembly 1, and the first disposed on the upper side (back surface side) of the membrane electrode assembly 1. The fuel cell stack is configured by stacking a plurality of cell units each including two separators 5.

A fuel gas outflow passage 53 that is formed between the membrane electrode assembly 1, the first separator 3, and the second separator 5 and that is at least one of gas passages through which gas can flow,
Both the water-repellent region 55 and the hydrophilic region 57 are formed on the inner surface of the fuel gas outflow passage 53 (gas passage), and the water-repellent region 55 is continuous over the entire length of the fuel gas outflow passage 53 (gas passage). It is a water repellent region continuous passage that is connected.

  Residual water is mixed in the gas (especially fuel gas) in the operating fuel cell. Therefore, if the residual water remains, the efficiency of exhausting the gas from the manifold is lowered.

  In the present embodiment, a water repellent region continuous passage in which the water repellent region 55 is continuously connected over the entire length of the fuel gas outflow passage 53 (gas passage) is set as the fuel gas outflow passage 53. Residual water is easily recirculated in the water-repellent region 55, and the water-repellent region 55 is continuously connected over the entire length of the fuel gas outflow passage 53. Therefore, the residual water mixed in the fuel gas can be efficiently discharged from the fuel gas outflow passage 53 to the fuel gas manifolds 9, 17, 31 (manifold).

(2) The fuel gas outflow passage 53 (water repellent region continuous passage) communicates with the fuel gas manifolds 9, 17, 31 (manifold) in the cell unit.

  Specifically, the outlet of the fuel gas outflow passage 53 is formed so as to continue to the fuel gas manifolds 9, 17, and 31. Accordingly, the residual water flowing out from the outlet of the fuel gas outflow passage 53 can be efficiently discharged to the fuel gas manifolds 9, 17, 31 (manifold).

(3) In the fuel gas outflow passage 53 (water repellent region continuous passage), the water repellent region is disposed on the lower side and the hydrophilic region is disposed on the upper side.

  Residual water accumulates on the lower side (vertically below) due to gravity, so by disposing the water-repellent region on the lower side, the residual water is more efficiently discharged to the fuel gas manifolds 9, 17, 31 (manifold). It can be made easier.

(4) The fuel gas outflow passage 53 (water repellent region continuous passage) is formed in a plurality of closed cross-sectional structures.

  Since the fuel gas outflow passage 53 has a plurality of closed cross-sectional structures, even if the discharge performance of the residual water from the predetermined fuel gas outflow passage 53 decreases, the residual water can be discharged from another fuel gas outflow passage 53. it can.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment described above, as described with reference to FIG. 7, the top portion 49 of the corrugated portion 45 of the second separator 5 abuts on the back side of the convex surface 25 of the first separator 3, thereby extending along the X direction. A plurality of fuel gas outflow passages 53 having a closed cross section are formed.

  However, as shown in FIG. 11, in the second embodiment, the height of the corrugated portion 145 of the second separator 105 is low, and the top portion 149 of the corrugated portion 145 extends to the back side of the convex surface 25 of the first separator 3. Not reached. The bottom surface of the bottom portion 147 is set to the same height as the general surface of the second separator 105. As shown in FIG. 11, the convex surface 25 of the first separator 3 and the corrugated portion 145 of the second separator 105 define one closed cross-section fuel gas outflow passage 153. Further, the wavy portion 145 extends along the Y direction, and the extending length is set to L. That is, any cross section of the extension length L is formed as shown in FIG.

  As shown in FIG. 12, in the second embodiment, the water repellent region 55 is formed on the entire upper surface of the wavy portion 145 of the second separator 105. The entire back surface of the convex surface 25 of the first separator 3 is formed in the hydrophilic region 57. The water repellent region 55 is formed over the entire length L of the undulating portion 145.

  Below, the effect by 2nd Embodiment is demonstrated.

(1) Since the height of the top portion 149 of the corrugated portion 145 is lower than the top portion 49 of the corrugated portion 45 in the first embodiment, even when the remaining amount of residual water is small, the residual water is efficiently along the bottom surface of the bottom portion 147. Can be discharged.

[Third embodiment]
Next, a third embodiment of the present invention will be described. Parts having the same configurations as those of the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment described above, as described with reference to FIG. 7, the top portion 49 of the corrugated portion 45 of the second separator 5 abuts on the back side of the convex surface 25 of the first separator 3, thereby extending along the X direction. A plurality of fuel gas outflow passages 53 having a closed cross section are formed.

  However, as shown in FIG. 13, in the third embodiment, a flat bottom surface 245 is formed in the second separator 205. As shown in FIG. 13, the fuel gas outflow passage 253 having a closed cross section is defined by the convex surface 25 of the first separator 3 and the bottom surface of the second separator 205. The bottom surface extends along the Y direction, and the extension length is set to L. That is, any cross section of the extended length L is formed as shown in FIG.

  As shown in FIG. 14, in the first mode, the water-repellent regions 55 and the hydrophilic regions 57 are alternately arranged on the bottom surface 245 of the second separator 205 at a predetermined interval in the X direction. The entire back side of the convex surface of the first separator is formed in the water-repellent region 55. The water repellent region 55 is formed over the entire length of the undulating portion extending length L.

  As shown in FIG. 15, in the second mode, the water-repellent regions 55 and the hydrophilic regions 57 are alternately arranged on the bottom surface 245 of the second separator 205 at predetermined intervals along the X direction. The entire back surface of the convex surface 25 of the first separator 3 is formed in the hydrophilic region 57. The water repellent region 55 is formed over the entire length of the extended length L.

  Below, the effect by 3rd Embodiment is demonstrated.

(1) The water-repellent regions 55 and the hydrophilic regions 57 are alternately arranged on the bottom surface 245 of the second separator 205 at a predetermined interval in the X direction. For this reason, residual water can be efficiently circulated along the extending direction of the fuel gas outflow passage 253.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. 16 and 17, and parts having the same configurations as those of the first to third embodiments are denoted by the same reference numerals and description thereof is omitted.

  In the first to third embodiments described above, the first separator 3 and the second separator 5 extend in the horizontal direction, and the first separator 3 and the second separator 5 are stacked in the vertical direction. .

  However, in the fourth embodiment, as shown in FIGS. 16 and 17, the first separator 3 and the second separator 5 extend in the vertical direction, and the first separator 3 and the second separator 5 are horizontal. Arranged in the direction. In this case, the wavy portion 45 of the second separator 5 extends in a wavy shape that undulates in the horizontal direction as it goes up and down, and a plurality of wavy portions 45 are formed. And the water-repellent area | region 55 is formed only in the wavy part 45 below the center part of the up-down direction of the wavy part 45 shown in FIG. That is, the water-repellent region 55 is formed only on the inner surface of the wavy portion 45 below the central portion in the vertical direction, and all other portions are formed in the hydrophilic region 57.

  Below, the effect by 4th Embodiment is demonstrated.

(1) According to the present embodiment, even when the first separator 3, the second separator 5, and the membrane electrode assembly 1 are formed in parallel in the lateral direction, the residual water is efficiently discharged. be able to.

  By the way, although the fuel cell stack of the present invention has been described by taking the above-described embodiment as an example, the present invention is not limited to this embodiment, and various other embodiments can be adopted without departing from the gist of the present invention.

  For example, in the above-described embodiment, the water repellent region continuous passage is the fuel gas outflow passage 53, 153, 253, but another gas passage may be set as the water repellent region continuous passage.

DESCRIPTION OF SYMBOLS 1 Membrane electrode assembly 3 1st separator 5 2nd separator 53 Fuel gas outflow passage (gas passage, water-repellent region continuous passage)
9, 17, 31 Fuel gas manifold (manifold)

Claims (4)

A plurality of cell units comprising a membrane electrode assembly, a first separator disposed on the front surface side of the membrane electrode assembly, and a second separator disposed on the back surface side of the membrane electrode assembly are laminated. A fuel cell stack,
At least one of these membrane electrode assemblies, a gas passage formed between the first separator and the second separator, through which gas can flow,
Both the water-repellent region and the hydrophilic region are formed on the inner surface of the gas passage, and the water-repellent region is a water-repellent region continuous passage continuously connected over the entire length of the gas passage. Fuel cell stack. The fuel cell stack according to claim 1, wherein
The water-repellent region continuous passage communicates with a manifold in the cell unit. The fuel cell stack according to claim 1 or 2,
In the water repellent region continuous passage, the water repellent region is disposed on the lower side, and the hydrophilic region is disposed on the upper side. The fuel cell stack according to any one of claims 1 to 3,
The water-repellent region continuous passage is formed in a plurality of closed cross-sectional structures.

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