JP4036760B2 - Separator structure for polymer electrolyte fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell, and more particularly to a separator structure for a polymer electrolyte fuel cell.
[0002]
[Prior art]
The unit cell of the smallest unit that the polymer electrolyte fuel cell generates electricity is composed of a fuel electrode catalyst layer composed of carbon or the like carrying a platinum catalyst from both sides, with a polymer electrolyte membrane (ion exchange membrane) in the center. A fuel electrode (anode) having a porous support layer made of carbon paper or the like as an electric material, an air electrode catalyst layer made of carbon or the like carrying a platinum catalyst, and a porous support layer made of carbon paper or the like as a current collecting material When a fuel cell is constructed by stacking unit cells from the outside to form a membrane / electrode assembly sandwiched between air electrodes (cathodes), the reaction gas such as hydrogen and oxygen supplied from the outside Is sandwiched between a reaction gas supply path for supplying the gas to the membrane / electrode assembly and a separator that also serves as an electrical connection between the unit cells.
[0003]
The power generation mechanism of this unit cell is that hydrogen gas supplied from the outside is distributed to a reaction gas supply path of a separator provided on the fuel electrode side, diffused by a porous support layer facing the reaction gas supply path, and fuel It is absorbed by the electrode catalyst layer, ionized on the platinum catalyst and separated into hydrogen ions and electrons. On the other hand, the oxygen gas supplied from the outside is distributed to the reaction gas flow path of the separator provided on the air electrode side, diffused by the porous support layer facing the reaction gas flow path, and absorbed by the air electrode catalyst layer, The hydrogen ions that have moved through the polymer electrolyte membrane on the platinum catalyst layer react with the electrons that have moved through the circuit connected to the outside to produce water. At this time, an electric current flows in the direction opposite to the flow of electrons flowing through a circuit connected to the outside, and electric energy can be obtained.
[0004]
In the electrochemical reaction described above, hydrogen ions move through the polymer electrolyte membrane with 2 to 3 water molecules. Therefore, in order for the polymer electrolyte membrane to ensure sufficient conductivity of hydrogen ions, it is indispensable to always keep the membrane wet. For this reason, the reaction gas is humidified and supplied. ing. However, the humidified reaction gas is condensed in the gas supply piping system, and the condensed water enters the unit cell via the gas supply manifold that supplies the reaction gas to the fuel cell in which the unit cells are stacked, and is parallel to the separator. The reaction gas channel provided may be blocked to inhibit the electrochemical reaction. In addition, the humidified reaction gas may condense in the separator, and the reaction gas flow path provided in parallel with the separator may be blocked as described above to inhibit the electrochemical reaction. On the other hand, the water produced by the reaction at the air electrode may obstruct the electrochemical reaction by closing the reaction gas flow path arranged in parallel with the separator. Therefore, in order to prevent this, the water supply body 11a is provided in the gas supply manifold 10 for supplying the reaction gas to the unit cells constituting the fuel cell, and the condensed water condensed in the piping system or the gas supply manifold 10 is captured. There is one that prevents the condensed water from flowing into the gas supply groove 6 provided in parallel with the separator plate 7 (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2001-155759 A (page 2-5, FIG. 2)
[0006]
[Problems to be solved by the invention]
However, disposing the water absorber inside the gas supply manifold that penetrates the fuel cell in which the unit cells are stacked is a difficult task. In addition, it is conceivable that the water absorbing body becomes dirty with the passage of time, and the electrical insulation between the stacked unit cells decreases. Furthermore, as the water absorbing body continues to absorb water, the water absorbing effect gradually decreases, and as a result, once the water absorbing body is filled with water, it flows into the separator and tends to cause water blockage of the reaction gas channel. In order to prevent this, it is conceivable to replace the water absorber with a new one when the water absorption effect of the water absorber is reduced, but as described above, take out the old water absorber from the fuel cell in which the unit cells are stacked, and replace the new water absorber. It is a difficult task to re-arrange, and since it cannot be used as a power source during replacement, the influence on the devices using the fuel cell as a power source cannot be ignored.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is arranged so as to sandwich a membrane / electrode assembly formed by joining an air electrode and a fuel electrode on both surfaces of an electrolyte membrane. In addition, a plurality of independent reaction gas flow paths are provided in parallel at the central portion, and a reaction gas supply manifold for supplying reaction gas from the outside to a peripheral portion and a reaction gas discharge manifold for discharging reaction gas to the outside are provided. A separator for a fuel cell in which a nozzle plate is attached between the reaction gas supply manifold and a gas inflow end of the reaction gas flow path, the nozzle plate having a substantially rectangular plate shape, and the reaction gas A plurality of convex nozzles are integrally formed in the supply manifold direction at the same interval as the reaction gas flow path, and the front end portion of the nozzle and the front of the nozzle plate are disposed at substantially the center of each of the nozzles. It is characterized in that the nozzle holes so as to penetrate the edge of the gas inlet end portion direction in the reaction gas flow path in the same direction is provided.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, the nozzle plate is configured so as to be parallel to the end portion from the end portion on the reaction gas supply manifold side of the reaction gas flow path. In the direction, a notch is provided in the thickness direction from the surface facing the separator in the previous period.
[0009]
The invention described in claim 3 of the present invention is the separator according to any one of claims 1 and 2, wherein in the separator, a water drainage channel is provided in an outer peripheral portion of the reaction gas channel, The position of the surface of the nozzle on the separator side from the position of the bottom surface of the opening of the extraction channel is located away from the separator in the thickness direction from the side of the separator where the reaction gas channel is provided. It is characterized by this.
[0010]
Further, in the invention described in claim 4 of the present invention, in any one of claims 1 to 3, the shape of the nozzle of the nozzle plate is a cross-sectional shape cut by a plane orthogonal to the nozzle direction. It is characterized in that it is constituted by any one of a substantially ◯ shape, a substantially △ shape, a substantially □ shape, a substantially ◇ shape, a substantially ▽ shape, or a combination thereof.
[0011]
Further, the invention described in claim 5 of the present invention is that, in any one of claims 1 to 4, the shape of the nozzle is maintained while maintaining a cross-sectional shape cut by a plane orthogonal to the nozzle direction. The cross-sectional area decreases toward the nozzle tip.
[0012]
Moreover, the invention described in claim 6 of the present invention is characterized in that, in any one of claims 1 to 5, a water absorbing material is provided in the vicinity of the nozzle in the gap between the nozzle and the separator. Is.
[0013]
The invention described in claim 7 of the present invention is the reaction gas channel according to any one of claims 3 to 6, wherein the end portion integrated with the nozzle is directed toward the drain channel. Inclined in the direction.
[0014]
The invention described in claim 8 of the present invention is characterized in that, in any one of claims 3 to 7, the water drainage channel is provided with a water absorbing material on the entire surface of the channel. is there.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. 2 to 11 (the same reference numerals are given to the same parts). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. As long as there is no description of the effect, it is not restricted to these aspects.
[0016]
2 and 3 show a first embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention. FIG. 2 is a perspective view of a nozzle plate 20 attached to the separator 30, and FIG. It is a fragmentary top view of the separator 30 of the state which attached A. As shown in FIG. 2, the shape of the nozzle plate 20 is a substantially rectangular plate, and the other end in the longitudinal direction protrudes from the end in the longitudinal direction on one surface of the plate. A plurality of convex nozzles 23 are provided in parallel to the short side direction, and further, a nozzle hole 24 is formed in a substantially central portion of the nozzle 23 so as to penetrate the entire length of the convex nozzle 23. Is provided.
[0017]
FIG. 3 shows a state in which the above-described nozzle plate 20 is attached between the reaction gas supply manifold 31 of the separator 30 and the gas inflow end portion 40 of the reaction gas flow path 33 provided in the separator 30. . In the separator 30, the polymer electrolyte membrane is located in the center, and both sides of the membrane / electrode assembly formed by sandwiching the both sides between the fuel electrode and the air electrode by the structure of the catalyst layer and the porous support layer are further separated from both sides. It is provided so as to be sandwiched between them, and is used to cause an electrochemical reaction by supplying a reaction gas to the membrane / electrode assembly, and is formed in a flat plate shape with a conductive carbon-based or metal-based material. . Here, the flow of the reaction gas will be described. The reaction gas supplied from the outside via the reaction gas supply manifold 31 enters the nozzle 24 provided in the nozzle 23 of the nozzle plate 20 described above. A plurality of the separators 30 are juxtaposed on the surface of the separator 30 and supplied to the reaction gas channel 33 formed by the continuous convex rib 32 and the concave bottom surface. It is diffused into the electrode assembly to cause an electrochemical reaction. Therefore, the nozzle holes 24 provided in the nozzles 23 of the nozzle plate 20 are formed at the same intervals as the reaction gas flow paths 33 provided in the separator 30. The purpose of passing the reaction gas through the nozzle hole 24 is that the pressure loss generated in the nozzle hole 24 dominates the pressure loss of the entire reaction gas flow path 33, so that the reaction gas flow path 33 is uniformly distributed, By sending a high-speed reaction gas into the reaction gas flow path 33 of the separator 30, water retention in the reaction gas flow path 33 is suppressed. If water retention occurs in the reaction gas flow path, a pressure difference is generated between the upstream and downstream of the water retention portion, and water is eliminated by the pressure difference.
[0018]
On the other hand, in a polymer electrolyte fuel cell, the polymer electrolyte membrane must always be in a wet state in order to ensure high conductivity with respect to hydrogen ions. For this purpose, the reaction gas is humidified and supplied to the membrane / electrode assembly. Therefore, when the condensed water 50 of the humidified reaction gas enters the nozzle plate 20 from the reaction gas supply manifold 31, it enters the nozzle hole 24 of the nozzle plate 20 to close the reaction gas flow path 33. It will be. Therefore, the tip of the nozzle hole 24 of the nozzle 23 provided in the nozzle plate 20 is sharpened so that the condensed water 50 does not enter the nozzle hole 24 so that the condensed water 50 does not easily enter.
[0019]
4 and 5 show a second embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention. FIG. 4 is a perspective view of a nozzle plate attached to the separator, and FIG. It is a fragmentary top view of the separator of a state. As shown in FIG. 4, the shape of the nozzle plate 20 is a substantially rectangular plate shape, and is plate-shaped from the end corresponding to the long side to the reaction gas flow path 33 while being parallel to the end. A notch 21 is provided in the thickness direction from one side of the. A plurality of convex nozzles 23 are formed integrally with the substantially rectangular plate shape from the end portion 22 other than the notch portion 21 within the thickness of the end portion 22 in parallel with the plate-like short direction. Furthermore, a nozzle hole 24 of a through hole is provided at a substantially central portion of the nozzle 23 so as to penetrate through an end corresponding to the long side on the opposite side.
[0020]
FIG. 5 shows a state in which the nozzle plate 20 of the second embodiment is mounted between the reaction gas supply manifold 31 of the separator 30 and the gas inflow end portion 40 of the reaction gas flow path 33 provided in the separator 30. Is. The function of the nozzle plate 20 of the second embodiment with respect to the reaction gas is basically the same as that of the nozzle plate 20 of the first embodiment, but the nozzle plate 20 of the second embodiment is a condensed water of the humidified reaction gas. When 50 enters the nozzle plate 20 from the reaction gas supply manifold 31, it enters the nozzle hole 24 of the nozzle plate 20 and closes the reaction gas flow path 33. Therefore, the tip of the nozzle hole 24 of the nozzle 23 provided in the nozzle plate 20 is sharpened so that the condensed water 50 does not enter the nozzle hole 24 so that the condensed water 50 does not enter. Further, the nozzle plate 20 is provided with a notch 21, and the condensed water 50 is pushed by the flow of the reaction gas supplied from the reaction gas supply manifold 31 and passes through the notch 21 and the reaction gas flow path 33. The water is discharged from the separator 30 through the drainage channel 34 provided in the peripheral portion of the. Moreover, since the nozzle hole 24 provided in the nozzle 23 of the nozzle plate 20 is provided at a position higher than the notch 21 through which the condensed water 50 passes, the surface of the separator 30 is not allowed to enter the condensed water 50. Absent.
[0021]
FIG. 6 shows a third embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention and is a cross-sectional view taken along the line AA of FIG. From the position of the bottom surface 36 of the opening of the drainage channel 34, the position of the surface of the nozzle 23 on the separator 30 side of the nozzle 23 is the side where the reaction gas channel 33 (see FIG. 5) of the separator 30 is provided. To the position away from the separator 30 in the thickness direction. Thereby, the condensed water 50 that has entered the separator 30 flows into the drain channel 34 before reaching the height of the convex nozzle 23. Therefore, the condensed water 50 does not enter the nozzle hole 24.
[0022]
FIG. 7 shows a fourth embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention, and is a partial perspective view showing the shape of the convex nozzle 23 of the nozzle plate 20 attached to the separator 30. . Each of the cross-sectional shapes orthogonal to the convex direction has a circular shape 4a, a Δ shape 4b, a □ shape 4c, and a ◇ shape 4d, and the ease of flow of the condensed water 50 that passes through the lowermost portion 35 of the nozzle 23, for supplying reactive gas. The reaction gas supplied from the manifold 31 is selected in consideration of the ease of entering the nozzle holes 24.
[0023]
FIG. 8 shows a fifth embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention, and is a partial perspective view showing the shape of the convex nozzle 23 of the nozzle plate 20 attached to the separator 30. FIG. Here, the cross-section has the shape shown in FIG. 6, and the cross-sectional area of the base portion is further increased, and the cross-sectional area is decreased toward the tip portion. Thereby, the condensed water 50 can be made difficult to enter through the nozzle holes 24.
[0024]
FIG. 9 shows a sixth embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention, and is a cross-sectional view of the nozzle plate 20 attached to the separator 30. This is one in which a water absorbing material 39 is provided in and around the lowermost portion 35 of the convex nozzle 23 of the nozzle plate 20 and the separator surface 38, and the condensed water 50 is directly sucked into the water absorbing material 39 to form nozzle holes. It is designed to prevent you from entering.
[0025]
FIG. 10 is a plan view showing a seventh embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention. This is because the end portion 37 of the nozzle 23 base portion of the nozzle plate 20 provided with the convex nozzles 23 of the nozzle plate 20 is directed toward the reaction gas flow channel 33 side toward the drainage flow channel 34 of the separator 30. It is a tilted structure. In this case, the passage of the condensed water 50 becomes wider as it goes in the direction of the drainage flow path 34, and the condensed water 50 easily flows toward the drainage flow path 34.
[0026]
FIG. 11 shows an eighth embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention, in which a water absorbing material 39 is provided for the entire length of the drainage channel 34. Thus, the condensed water 50 that has flowed into the drainage channel 34 is reliably captured, and at the same time, the reaction gas is prevented from leaking from the drainage channel 34.
[0027]
【The invention's effect】
As described above, in the separator structure for a polymer electrolyte fuel cell of the present invention, by attaching a nozzle plate to the separator, the reaction gas supplied from the reaction gas supply manifold is uniformly distributed in the reaction gas flow path. When water can be distributed in the reaction gas flow path, a pressure difference is generated between the upstream and downstream of the water retention portion by the increased reaction gas, and water can be immediately removed. In addition, by providing a drainage channel in the separator, even if condensed water flows, it can be discharged through the drainage channel through the gap between the nozzle and separator provided in the nozzle plate, and by providing a water absorbing material, Therefore, even if the operation is performed for a long time, it is possible to generate power stably and efficiently.
[Brief description of the drawings]
FIG. 1 is described in FIG. 2 in Reference Document 1 (Japanese Patent Laid-Open No. 2001-155759).
FIG. 2 is a perspective view of a nozzle plate attached to a separator having a separator structure for a polymer electrolyte fuel cell according to a first embodiment of the present invention.
FIG. 3 is a partial plan view of the separator in a state where a nozzle plate having a separator structure for a polymer electrolyte fuel cell according to the first embodiment of the present invention is attached.
FIG. 4 is a perspective view of a nozzle plate attached to a separator having a separator structure for a polymer electrolyte fuel cell according to a second embodiment of the present invention.
FIG. 5 is a partial plan view of a separator in a state in which a nozzle plate having a separator structure for a polymer electrolyte fuel cell according to a second embodiment of the present invention is attached.
6 is a cross-sectional view taken along the line AA of FIG. 5, showing the relationship between the nozzle plate and the drainage channel of the third embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention.
FIG. 7 is a partial perspective view showing the shape of a nozzle of a nozzle plate attached to the separator of the fourth embodiment of the separator structure for a polymer electrolyte fuel cell according to the present invention.
FIG. 8 is a partial perspective view showing the shape of a nozzle of a nozzle plate attached to a separator of a fifth embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention.
FIG. 9 is a cross-sectional view of a nozzle plate attached to a separator of a sixth embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention.
FIG. 10 is a plan view showing a seventh embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention.
FIG. 11 is a plan view showing an eighth embodiment of a separator structure for a polymer electrolyte fuel cell according to the present invention.
[Explanation of symbols]
20 Nozzle plate 21 Notch portion 22 End portion other than the notch portion 23 Nozzle 24 Nozzle hole 30 Separator 31 Reactant gas supply manifold 32 Rib 33 Reactant gas channel 34 Drain channel 35 Bottom of nozzle 36 Low drain channel Surface 37 End portion 38 of nozzle root portion Separator surface 39 Water absorbing material 40 Gas inflow end portion 50 Condensed water

Claims (8)

  Arranged so that a membrane / electrode assembly formed by joining an air electrode and a fuel electrode on both sides of the electrolyte membrane is sandwiched, and a plurality of independent reaction gas channels are arranged in parallel at the center, A reaction gas supply manifold that supplies reaction gas from the outside and a reaction gas discharge manifold that discharges reaction gas to the outside are provided. Between the reaction gas supply manifold and the gas inflow end of the reaction gas channel, A fuel cell separator to which a nozzle plate is attached, wherein the nozzle plate has a substantially rectangular plate shape, and a plurality of convex nozzles at the same interval as the reaction gas flow path in the direction of the reaction gas supply manifold. Are integrally formed, and penetrate the tip of the nozzle and the end of the nozzle plate in the direction of the gas inflow end in the same direction as the reaction gas flow path at substantially the center of each of the nozzles. Separator structure for a solid polymer fuel cell, wherein the nozzle hole is provided as.   The nozzle plate is provided with a cutout in the thickness direction from the surface facing the separator in the direction of the reaction gas flow path in the direction of the reaction gas flow path from the end on the reaction gas supply manifold side in parallel with the end. The separator structure for a polymer electrolyte fuel cell according to claim 1, wherein In the separator, a drainage channel is provided on the outer periphery of the reaction gas channel, and the position of the surface of the nozzle on the separator side from the position of the bottom of the opening of the drainage channel is the position of the separator. The separator for a polymer electrolyte fuel cell according to any one of claims 1 and 2 , wherein the separator is located at a position away from the separator in a thickness direction from a side where the reaction gas flow path is provided. Construction.   As for the shape of the nozzle of the nozzle plate, the cross-sectional shape cut by a plane orthogonal to the nozzle direction is approximately ○ shape, approximately Δ shape, approximately □ shape, approximately ◇ shape, approximately ▽ shape, or these The separator structure for a polymer electrolyte fuel cell according to any one of claims 1 to 3, wherein the separator structure is a combination.   5. The nozzle according to claim 1, wherein the nozzle has a cross-sectional area that decreases toward the tip of the nozzle while maintaining a cross-sectional shape cut by a plane orthogonal to the nozzle direction. A separator structure for a polymer electrolyte fuel cell according to the item.   The separator structure for a polymer electrolyte fuel cell according to any one of claims 1 to 5, wherein a water absorbing material is provided in the vicinity of the nozzle in the gap between the nozzle and the separator.   The solid polymer according to any one of claims 3 to 6, wherein an end integrated with the nozzle is inclined in a direction of a reaction gas channel toward the drain channel. Separator structure for fuel cell.   The separator structure for a polymer electrolyte fuel cell according to any one of claims 3 to 7, wherein the water drainage channel is provided with a water absorbing material on the entire surface of the channel.

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