JP2000123848A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the clogging of a gas flow passage by smoothly and properly removing moisture in the gas flow passage. SOLUTION: This fuel cell is equipped with a first separator and a second separator 14 and 16 for clamping a unit fuel cell 12, and drainage grooves 44a to 44c continuing from a gas inlet to a gas outlet are formed on a bottom wall 42a for constituting first and second flow passages 38 and 46. According to this construction, clogging with water in the first or the second flow passage 38 or 46 can be avoided and the unit fuel cell 12 can stably generate power, thereby effectively improving the function of the whole of a fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell having a unit fuel cell sandwiched between first and second separators.

[0002]

2. Description of the Related Art For example, a solid polymer fuel cell has a unit comprising an electrolyte comprising a polymer ion exchange membrane (cation exchange membrane) and an anode electrode and a cathode electrode respectively disposed on both sides of the electrolyte. The fuel cell is sandwiched between separators to constitute a fuel cell stack.

In this type of fuel cell, a fuel gas, for example, hydrogen gas, supplied to an anode electrode is hydrogen-ionized on a catalyst electrode and moves to a cathode electrode via a moderately humidified electrolyte. I do. The electrons generated during that time are taken out to an external circuit and used as DC electric energy. Since an oxidant gas, for example, oxygen gas or air is supplied to the cathode side electrode, the hydrogen ions, the electrons, and oxygen react at the cathode side electrode to generate water.

Incidentally, an electrolyte comprising a polymer ion exchange membrane needs to be sufficiently humidified in order to maintain ion permeability. Therefore, in general, the oxidizing gas and the fuel gas are humidified by using a gas humidifying device provided outside the fuel cell, and the oxidizing gas and the fuel gas are sent to the fuel cell as water vapor to humidify the electrolyte. Is configured.

[0005]

However, polymer electrolyte fuel cells have a relatively low operating temperature (up to 100
° C), water that has not been absorbed by the electrolyte or water generated by the reaction may be present in a liquid (water) state among the water supplied for humidification. It has been pointed out that this water closes the gas passage of the gas diffusion layer, reduces the diffusibility of the reaction gas, the fuel gas and the oxidizing gas, into the electrode catalyst layer, and significantly degrades the cell performance. I have.

Therefore, for example, Japanese Patent Application Laid-Open No. Hei 8-130025
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, an electrolyte layer, an electrode forming a power generation layer by sandwiching the electrolyte layer, and a fuel flow path (gas flow path) by the electrode sandwiching the power generation layer. And a flow path forming member to be formed.
There is known a fuel cell in which a plurality of short fibers made of carbon are planted on a surface forming the flow path. In this fuel cell, it is described that water generated in a gas flow path is drawn to carbon short fibers, then vaporized from the surface of the carbon short fibers and discharged from the gas flow path.

However, a relatively large amount of water is easily generated in the gas flow path, and the short carbon fibers contain more water than can be vaporized from the surface of the short carbon fibers. that time,
Multiple short carbon fibers are planted in the gas flow path,
It has been pointed out that the short carbon fiber prevents the smooth flow of water, and the drainage property is extremely poor.

The present invention has been made to solve this kind of problem, and it is possible to smoothly and surely remove water in a gas flow path, and to effectively prevent the gas flow path from being blocked. It is an object to provide a possible fuel cell.

[0009]

In the fuel cell according to the present invention, the first separator has a first flow path for supplying fuel gas to the anode electrode, and the second separator supplies oxidant gas to the cathode electrode. It has a second flow path to supply, at least on the wall surface forming the first or second flow path,
A drain groove continuous from the gas inlet side to the gas outlet side is provided. Therefore, the water generated in the first or second flow path smoothly moves to the gas outlet side along the drain groove,
Effective drainage can be ensured by avoiding blockage of the first or second flow path. In particular, the drain groove is continuous from the gas inlet side to the gas outlet side, and water generated in the first or second flow path is smoothly and reliably discharged to the gas outlet side along the drain groove. You.

The depth and width of the drain groove are set to remove water by capillary action. As a result, the water that has blocked or is about to block the first or second flow path is discharged to the outside of the first or second separator. In addition, the water adhering to the wall surfaces of the first and second flow paths, that is, the bottom wall surface, the side wall surface, or the upper wall surface, is surely dispersed by capillary action, and thus the first and second flow paths are dispersed.
Alternatively, it is discharged outside the second flow path.

[0011] Further, the first or second flow path is set in a plurality of lines that are independently continuous from the gas inlet side to the gas outlet side, and the drain groove is formed in each of the first or second flow path. Is formed on at least one continuous wall independently from the gas inlet side to the gas outlet side. Therefore, the condensed water of the water contained in the fuel gas and the oxidizing gas and the reaction product water are discharged to the outside of the first or second separator along the plurality of drain grooves, respectively.
It is possible to reliably prevent the first or second flow path from being blocked by water.

[0012]

FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to a first embodiment of the present invention, and FIG.
FIG. 2 is a partially sectional explanatory view of the fuel cell 10.

The fuel cell 10 includes a unit fuel cell 12
And first and second separators 14 and 16 for sandwiching the unit fuel cell 12, and a plurality of sets are stacked as needed to form a fuel cell stack. The unit fuel cell 12 includes a solid polymer electrolyte membrane 18
And an anode electrode 20 and a cathode electrode 22 provided with the electrolyte membrane 18 interposed therebetween.

First and second gaskets 24 and 26 are provided on both sides of the unit fuel cell 12. The first gasket 24 has a large opening 28 for accommodating the anode 20. The second gasket 2
6 has a large opening 30 for accommodating the cathode-side electrode 22. The unit fuel cell 12 and the first and second gaskets 24 and 26 are sandwiched between the first and second separators 14 and 16.

A fuel gas supply hole 32a, an oxidizing gas supply hole 34a, and a cooling water supply hole 36a are formed on the upper sides of the first and second separators 14, 16, and the first and second separators 14, 16 are formed. A fuel gas discharge hole 32b, an oxidizing gas discharge hole 34b, and a cooling water discharge hole 36b are formed below the two separators 14, 16. Similarly, a fuel gas supply hole 32a, an oxidant gas supply hole 34a, and a cooling water supply hole 36a are formed on the upper side of the electrolyte membrane 18 and the first and second gaskets 24 and 26. A fuel gas discharge hole 32b, an oxidizing gas discharge gas 34b, and a cooling water discharge hole 36b are formed on the lower side.

On the surface 14a of the first separator 14, a first flow path 38 for supplying hydrogen gas as a fuel gas to the anode 20 is formed. As shown in FIG. 3, the first flow path 38 communicates with the fuel gas supply hole 32 a provided on the upper side of the first separator 14, and the fuel gas supply hole 32 a provided on the lower side of the first separator 14. It communicates with the discharge hole 32b.

The first flow path 38 has, for example, four independent flow path grooves 40a to 40d, respectively. Each of the flow grooves 40a to 40d meanders in the vertical direction so as to extend once in the direction of gravity (the direction of arrow A) from the fuel gas supply hole 32a and then in the direction of antigravity, and To the right (in the direction of the arrow B) from the fuel gas discharge hole 32b. As shown in FIG. 2, the flow grooves 40 a to 40 d are respectively formed on the surface 1 of the first separator 14.
4a side, a bottom wall surface 42a, a side wall surface 42b, and an upper wall surface 42
c, and the bottom wall surface 42
For example, four drain grooves 44a to 44c are formed in a.

The grooves 44a to 44c are provided continuously from the fuel gas supply hole 32a on the gas inlet side to the fuel gas discharge hole 32b on the gas outlet side, and have a V-shaped opening cross section. . The depths D and the widths H of the grooves 44a to 44c are set in order to remove water by capillary action. In the present embodiment, the depth D is 1 μm
The width H is set within a range of about 0.5 μm.
Is set in the range of 1 μm to 0.5 μm. The grooves 44a to 44c are subjected to a hydrophilic treatment to more effectively discharge water.

As shown in FIG. 4, a second flow path 46 for supplying air (or oxygen gas) as an oxidizing gas to the cathode 22 is provided on the surface 16a of the second separator 16.
Is formed. The second flow path 46 has four flow grooves 48a to 48d, like the first flow path 38. Channel groove 4
In FIG. 4, 8a to 48d are provided from the left side to the right side (in the direction of arrow B) while meandering in the vertical direction, and both ends thereof are connected to the oxidant gas supply hole 34a which is the gas inlet side and the gas outlet side. It is continuous with a certain oxidizing gas discharge hole 34b.

As shown in FIG. 2, the second separator 16 has discharge grooves 44a to 44c formed on the bottom wall surface 42a that forms the flow grooves 48a to 48d. The respective surfaces 14b, 16 of the first and second separators 14, 16
The cooling water supply hole 36a and the cooling water discharge hole 36
and a cooling water flow passage 50 communicating with the cooling water flow path b.

The operation of the fuel cell 10 according to the first embodiment thus formed will be described below.

For example, hydrogen gas as a fuel gas is supplied to the first flow path 38 from the fuel gas supply hole 32 a provided on the upper side of the first separator 14 and provided on the upper side of the second separator 16. An oxidizing gas, for example, air (or oxygen gas) is supplied to the second flow path 46 from the oxidizing gas supply hole 34a. The hydrogen gas supplied to the first flow channel 38 is introduced into flow channel grooves 40a to 40d provided independently of each other, and moves in the direction of arrow B so as to meander in the vertical direction while the unit fuel cell 12 To the anode-side electrode 20. On the other hand, the second flow path 46
Is moved in the direction of arrow B while meandering in the vertical direction along the channel grooves 48a to 48d which are similarly provided independently, and the cathode-side electrode constituting the unit fuel cell 12 22.

Here, the hydrogen gas supplied to the first flow path 38 contains water vapor for humidification in advance. For this reason, in some cases, water vapor condenses without being absorbed by the electrolyte membrane 18 and exists in a water state.
8 easily stays in each of the flow channel grooves 40a to 40d,
There is a possibility that the hydrogen gas does not easily flow along the flow channels 40a to 40d or does not flow.

Therefore, in the first embodiment, the flow channel 40
groove portions 44a-4 set to a depth D and a width dimension H at which a capillary phenomenon can occur on a bottom wall surface 42a forming a to 40d.
4c are provided, and the grooves 44a to 44c are continuous from the fuel gas supply hole 32a to the fuel gas discharge hole 32b. Therefore, water existing in the flow channels 40a to 40d is surely dispersed in the grooves 44a to 44c by the capillary action,
Further, the flow rate of the hydrogen gas flowing through the grooves 44a to 44c allows the gas to be smoothly drained to the fuel gas discharge hole 32b on the gas outlet side.

Thus, the flow grooves 40a to 40d are not likely to be clogged with water or clogged. Therefore, uniform gas distribution along the first flow path 38 is stably continued, all the unit fuel cells 12 can be stably generated, and the performance of the entire fuel cell 10 can be easily improved. The effect of being achieved is obtained.

Moreover, the grooves 44a to 44c are subjected to a hydrophilic treatment, so that the water generated in the flow grooves 40a to 40d can be discharged more effectively. Also,
If the grooves 44a to 44c are set to be inclined downward in the flow direction of the hydrogen gas, there is an advantage that the drainage work can be performed more smoothly.

On the other hand, in the second flow path 46, water containing condensation of water vapor contained in the air and water produced by the reaction is likely to be present. At this time, each channel groove 48a to 48d constituting the second channel 46 is formed.
Are formed with grooves 44a to 44c, and water is smoothly dispersed by capillary action, and the same effect as that of the first flow path 38 can be obtained. Note that the grooves 44a to 44c are
At least one of the first flow path 38 and the second flow path 46 may be provided.

FIG. 5 is a partially sectional explanatory view of a first separator 60 constituting a fuel cell according to a second embodiment of the present invention. The first separator 60 is provided with a first flow path 62 for supplying a fuel gas, for example, a hydrogen gas, and five independent discharge grooves are formed on an upper wall surface 64 forming the first flow path 62. 66 are formed. Like the grooves 44a to 44c, each groove 66 has a depth D and a width H set to remove water by capillary action.

The first separator 60 thus configured
In this case, water generated by condensation of water vapor in the hydrogen gas supplied to the first flow path 62 is converted into each groove 66 by capillary action.
And is smoothly discharged to the outside of the first separator 60. Thus, the same effects as those of the first embodiment can be obtained, such that the first flow path 62 does not become clogged with water or does not become clogged.

FIG. 6 is a partially sectional explanatory view of a first separator 70 constituting a fuel cell according to a third embodiment of the present invention. The first separator 70 is provided with a first flow path 72 for supplying hydrogen gas, and the bottom wall 74a, the side wall 74b, and the upper wall 74c that form the first flow path 72 have 5 An independent drain groove 76 is formed for the book. Each of the groove portions 76 includes a groove portion 44a-44.
In order to remove water by capillary action as in c, the depth D and the width dimension H are set.

The first separator 70 thus configured
Then, when water in the hydrogen gas supplied to the first flow path 72 is condensed to generate water, the bottom wall surface 74a and the side wall surface 74a
This water is surely dispersed in each of the groove portions 76 formed on the upper surface b and the upper wall surface 74c. Accordingly, the same effects as in the first and second embodiments can be obtained, such that water does not stay in the first flow path 72 and the power generation performance of the fuel cell can be effectively improved.

FIG. 7 is a partially sectional explanatory view of a first separator 80 constituting a fuel cell according to a fourth embodiment of the present invention, and FIG. 8 is a fuel cell according to a fifth embodiment of the present invention. FIG. 2 is a partial cross-sectional explanatory view of a first separator 90 constituting a battery.

The first separators 80 and 90 are provided with first flow paths 82 and 92, respectively.
The bottom wall surfaces 84 and 94 constituting the second 2 are formed with five independent drainage grooves 86 and 96. Each groove 86,
The opening section has a semicircular shape, and each groove 96 has a short opening section shape.

Therefore, in the fourth and fifth embodiments,
By setting the depth D and the width dimension H of each of the groove portions 86 and 96, the same effects as those of the first to third embodiments can be obtained, for example, a capillary phenomenon is caused and an effective drainage effect is obtained.

In the second to fifth embodiments, the description of the second separator for supplying the oxidizing gas is omitted, but the first separators 60, 70, 80 and 90 are omitted.
With the same configuration as described above, the same effect can be obtained.

[0036]

In the fuel cell according to the present invention, at least the wall forming the first or second flow path is provided with a drain groove continuous from the gas inlet side to the gas outlet side. Water generated in the road is smoothly and reliably discharged through the drain groove. Thereby, the first or second
The blockage of the flow path by water can be avoided, the unit fuel cells can be stably generated, and the performance of the entire fuel cell can be effectively improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a fuel cell according to a first embodiment of the present invention.

FIG. 2 is a partially sectional explanatory view of the fuel cell.

FIG. 3 is an explanatory front view of a first separator constituting the fuel cell.

FIG. 4 is an explanatory front view of a second separator constituting the fuel cell.

FIG. 5 is an explanatory partial cross-sectional view of a first separator included in a fuel cell according to a second embodiment of the present invention.

FIG. 6 is a partially sectional explanatory view of a first separator constituting a fuel cell according to a third embodiment of the present invention.

FIG. 7 is a partially sectional explanatory view of a first separator constituting a fuel cell according to a fourth embodiment of the present invention.

FIG. 8 is a partially sectional explanatory view of a first separator constituting a fuel cell according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Unit fuel cell 14, 16, 60, 70, 80, 90 ... Separator 18 ... Electrolyte membrane 20 ... Anode side electrode 22 ... Cathode side electrode 24, 26 ... Gasket 32a ... Fuel gas supply hole part 32b ... fuel gas discharge holes 34a ... oxidant gas supply holes 34b ... oxidant gas discharge holes 36a ... cooling water supply holes 36b ... cooling water discharge holes 38, 46, 62, 72, 82, 92 ... flow paths 40a to 40d, 48a to 48d: flow channel 42a, 74a, 84, 94: bottom wall surface 42b, 74b: side wall surface 42c, 64, 74c
... Upper wall surfaces 44a to 44c, 66, 76, 86, 96 ... Grooves

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Manabu Tanaka 1-4-1 Chuo, Wako City, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Akio Yamamoto 1-4-1 Chuo Wako City, Saitama Prefecture Co., Ltd. Within Honda R & D Co., Ltd. (72) Inventor Yosuke Fujii 1-4-1 Chuo, Wako-shi, Saitama F-term within Honda R & D Co., Ltd. 5H026 AA02 AA06 CC03

Claims (3)

[Claims] 1. A unit fuel cell comprising an electrolyte sandwiched between an anode electrode and a cathode electrode; and first and second separators sandwiching the unit fuel cell, wherein the first separator comprises: A first flow path for supplying a fuel gas to the anode electrode; and a second flow path for supplying an oxidizing gas to the cathode electrode, wherein the second separator has at least the first or second flow path. A fuel cell, characterized in that a drain groove continuous from a gas inlet side to a gas outlet side is provided on a wall surface forming a flow path. 2. The fuel cell according to claim 1, wherein the drain groove has a depth and a width set to remove water by capillary action. 3. The fuel cell according to claim 1, wherein the first or second flow path is provided in a plurality of lines that are independently continuous from the gas inlet side to the gas outlet side. The fuel is characterized in that at least one drain groove is provided on each wall surface forming each of the first or second flow passages, independently from the gas inlet side to the gas outlet side. battery.