JP2003086197A - Separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for supplying fuel gas and oxidizing gas more evenly to an electrode. SOLUTION: Bent ribs 42a, 42b and 46 are formed on the outer periphery of the bent sections of two U-shaped flow passages formed by flow-passage forming ribs 34, 36 and 38 on the surface of the separator 20, the bent ribs serving as integrally continuing projecting parts to form a U-shaped channel along the shape of the bent section of each of the U-shaped flow passages. A plurality of approximately square bent protrusions 44 and 48 are formed on the inner periphery of the bent sections. The bent ribs 42a, 42b and 46 and the plurality of bent protrusions 44 and 48 prevent the fuel gas and the oxidizing gas from collecting on the inner periphery of the bent sections when flowing, while also preventing moisture from remaining on the inner periphery. As a result, when a fuel-cell stack is formed, the fuel gas and the oxidizing gas can be evenly supplied to the entire electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator for a fuel cell, and more specifically, it has a plurality of convex portions that come into contact with electrodes to form a flow path for fuel gas or oxidizing gas, and is laminated with the electrodes. The present invention relates to a fuel cell separator that forms a partition wall between unit cells when a fuel cell stack is formed.

[0002]

2. Description of the Related Art Conventionally, as a separator for a fuel cell of this type, as shown in the conventional separator in FIG. 4, a flow path for fuel gas or oxidizing gas formed by a gas diffusion electrode is used. Two U as a whole due to the passage forming rib
The flow path is guided by a plurality of linear ribs in the shape of a straight line, and the portion where the flow direction changes, that is, the bent portion of the U-shaped flow path, has a plurality of square-shaped convex portions with a square cross-section. It has been proposed to improve the diffusivity and change the flow direction of the fuel gas or the oxidizing gas (for example, Japanese Patent Laid-Open No. 10-106594). According to this conventional separator, the fuel gas and the oxidizing gas can be uniformly supplied to the entire gas diffusion electrode.

[0003]

However, in the separator of this conventional example, there is a problem that a large amount of gas flows on the inner peripheral side and does not flow much on the outer peripheral side at the portion where the flow direction of the fuel gas or the oxidizing gas changes. It was happening. This problem hinders the uniform supply of the fuel gas and the oxidizing gas to the gas diffusion electrode, so that the performance of the fuel cell cannot be sufficiently exhibited.

Further, since the fuel cell generates electricity by the reverse reaction of the electrolysis of hydrogen and oxygen, water is generated on one side of the gas diffusion electrode, and the gas flow path is blocked by the water, and the gas flow after that. It also creates the problem of not much gas flowing in the road. Further, in the case of the solid polymer electrolyte membrane, since the gas is supplied with a water content contained therein in order to maintain the performance of the membrane, it is possible that the water content condenses and blocks the gas flow path. Therefore, giving due consideration to the drainage property of the separator leads to the uniform supply of the fuel gas and the oxidizing gas, and further, the improvement of the performance of the fuel cell.

The purpose of the separator for a fuel cell of the present invention is to solve these problems and to more uniformly supply the fuel gas and the oxidizing gas to the electrodes.

[0006]

Means for Solving the Problems and Actions and Effects Thereof The fuel cell separator of the present invention employs the following means in order to achieve the above object.

The first fuel cell separator of the present invention has a plurality of convex portions that contact the electrodes to form flow paths for fuel gas and oxidizing gas, and are stacked with the electrodes to form a fuel cell stack. A separator for a fuel cell forming a partition wall between unit cells when formed, wherein the convex portion in a portion that changes the flow direction of the gas is formed so as to limit diffusion of the gas toward the outer peripheral side. Is the gist.

In the first fuel cell separator of the present invention, the convex portion at the portion for changing the gas flow direction is
Since it is formed so as to limit the diffusion of gas toward the outer peripheral side, the diffusion of gas is restricted on the outer peripheral side where gas flow is difficult to ensure a sufficient gas flow on the outer peripheral side and the gas flow direction on the inner peripheral side. The degree of freedom can be secured to prevent the retention of water on the inner peripheral side. As a result, the gas can be uniformly supplied to the entire electrode, and the performance thereof can be further improved when the fuel cell stack is formed by stacking the gas with the electrode and the like.

A second fuel cell separator according to the present invention has a plurality of convex portions that come into contact with electrodes to form flow paths for fuel gas and oxidizing gas, and is laminated with the electrodes to form a fuel cell stack. A separator for a fuel cell that forms partition walls between unit cells when formed, wherein at least a part of the convex portion on the outer peripheral side in a portion that changes the flow direction of the gas is at least a predetermined value along the flow direction of the gas. The gist is that the convex portions on the inner peripheral side of the portion are integrally formed over the front and rear of the portion and are discretely formed.

In the second fuel cell separator of the present invention, at least a part of the convex portion on the outer peripheral side in the portion for changing the gas flow direction extends along the gas flow direction at least before and after the predetermined position. Since the convex portion on the inner peripheral side of the portion formed integrally is formed discretely, sufficient gas is supplied to the outer peripheral side where the gas tends to stagnant at the portion where the gas flow direction is changed. It is possible to prevent the retention of water on the inner peripheral side. As a result, the gas can be uniformly supplied to the entire electrode, and the performance thereof can be further improved when the fuel cell stack is formed by stacking the gas with the electrode and the like.

In the second fuel cell separator of the present invention, the portion for changing the flow direction of the gas is
A plurality of corners that change the flow direction may be provided, and the predetermined portion may be the corner.

In the second fuel cell separator of the present invention, the predetermined portion may be a portion for changing the flow direction of the gas.

Further, in the second fuel cell separator of the present invention, the convex portion on the outer peripheral side of the portion for changing the flow direction of the gas is formed such that the flow channel groove becomes narrower toward the downstream side. Can also be In this way, it is possible to prevent the flow rate from decreasing due to the consumption of the fuel gas and the oxidizing gas.

Further, in the second fuel cell separator of the present invention, the convex portion on the inner peripheral side in the portion for changing the flow direction of the gas is formed in a substantially circular shape or a substantially square shape in cross section. It can also be one.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram showing an outline of the configuration of a separator 20 for a fuel cell which is an embodiment of the present invention. The separator 20 is formed of dense gas-impermeable carbon. As shown in the figure, near each side of the separator 20, a fuel gas introduction hole 22 for introducing a fuel gas (for example, a hydrogen-rich gas containing hydrogen) to the surface of the separator 20 and a fuel gas in another unit are provided. A fuel gas communication hole 23 for communicating with the cell, a fuel gas discharge hole 24 for discharging the fuel gas from the separator 20, and an oxidizing gas (for example, air containing oxygen) are introduced into the back surface of the separator (not shown). For introducing the oxidizing gas, an oxidizing gas connecting hole 27 for connecting the oxidizing gas with other unit cells, and this oxidizing gas for the separator 2
Oxidizing gas discharge hole 28 for discharging from 0 and cooling water holes 30 and 32 forming a water passage of cooling water are formed. Although these holes are not shown, when the fuel cell stacks are stacked to form a fuel cell stack, a flow path is formed for inflow or outflow of the fuel gas, the oxidizing gas, or the cooling water in the stacking direction of the fuel cell stack. A fuel gas or an oxidizing gas is supplied to each cell in the cell stack, and cooling water is supplied to each cooling member that is regularly stacked to cool the fuel cell stack.

On the surface of the separator 20, the fuel gas introduced from the fuel gas introduction hole 22 flows in a U shape as a whole to reach the fuel gas communication hole 23, and the fuel gas communication hole 2 is formed.
Similarly, three flow passage forming ribs 34, 36, which form a flow passage from U to U shape and are discharged to the fuel gas discharge hole 24,
38 is formed. These three flow path forming ribs 34,
A plurality of projections 40 having a substantially square cross section that form a grid-like flow path groove are formed in the linear portion of the two U-shaped flow paths formed by 36 and 38, and the projections 40 for fuel gas to the electrode are formed. It ensures efficient diffusion and sufficient contact with the electrodes. In the bent portion of the two U-shaped flow paths, on the outer peripheral side,
An integral continuous bent portion rib 42 that forms one U-shaped or a plurality of evenly spaced channel grooves along the bent shape.
a, 42b, and 46 are formed to prevent the fuel gas from flowing toward the inner peripheral side of the bent portion, and to allow the fuel gas to sufficiently flow to the outer peripheral side. On the inner peripheral side of the bent portion, a plurality of discrete bent portion protrusions 44 each having a substantially square cross section are formed similarly to the linear portion of the U-shaped flow path. The flow channel groove is formed to prevent water from staying in the bent portion and prevent the flow of fuel gas from being hindered. Further, even if water stays in a part of the bent portion, the fuel gas can be diverted from the other direction, so that it is possible to prevent the gas flow in the subsequent flow passages from being obstructed.

On the back surface of the separator 20, although not shown, two U-shapes in which the oxidizing gas introduced from the oxidizing gas introducing hole 26 is discharged to the oxidizing gas discharge hole 28 via the oxidizing gas communication hole 27. The flow paths are formed in the same manner as the two U-shaped flow paths of the fuel gas on the surface of the separator 20 illustrated in FIG. Therefore, the description of the back surface of the separator 20 is omitted because it is redundant.

The separator 2 of the embodiment thus constructed
Reference numeral 0 denotes a fuel cell (not shown) which is laminated together with an electrolyte membrane 50, a fuel gas side electrode 52, and an oxidizing gas side electrode 54, which constitute a cell illustrated as a unit cell configuration diagram of a polymer electrolyte fuel cell in FIG. A stack for Note that FIG.
In the unit cell illustrated in FIG. 1, the electrolyte membrane 50 is formed of a proton conductive membrane formed of a solid polymer material such as a fluorine resin, and the electrodes 52 and 54 are made of platinum or platinum and another metal. It is formed of carbon cloth in which an alloy catalyst is kneaded.

According to the separator 20 of the embodiment described above, the bent portion ribs 42a, 42b are integrally continuous on the outer peripheral sides of the bent portions of the two U-shaped passages along the shape of the bent portion.
Since the inner peripheral side is formed by a plurality of bent portion protrusions 44 having a substantially square cross section, the fuel gas and the oxidizing gas can be sufficiently flowed to the outer peripheral side of the bent portion and the flow path on the inner peripheral side is formed. It is possible to prevent the retention of water in the interior and supply the fuel gas and the oxidizing gas evenly to the entire electrode. As a result, when the separator 20 is laminated with the electrodes 52, 54 and the like to form a fuel cell stack, the performance can be further improved.

In the separator 20 of the embodiment, a plurality of bent portion ribs 42 are formed on the outer peripheral side of the bent portion in the two U-shaped flow passages so as to form flow passage grooves having equal intervals before and after the bent portion.
Although a and 42b are formed, as illustrated in the bent rib of the modified example of FIG. 3, the flow path groove is bent toward the downstream side in consideration of the decrease in the gas flow rate accompanying the gas consumption due to power generation. The ribs 142a and 142b may be formed.

In the separator 20 of the embodiment, bent ribs 42a, 42b, 46 forming U-shaped flow channel grooves are formed on the outer peripheral side of the bent portions in the two U-shaped flow channels. The linear portion formed on the outer peripheral side of the portion does not need to be formed by an integral continuous rib. As illustrated in the bent portion rib of the modified example of FIG. 4, the two corners of the U-shape are A continuous L-shaped rib 2 which is integrated over the front and rear thereof
42a and 242b may be formed, and a plurality of protrusions 243 may be formed in the U-shaped linear portion.

In the separator 20 of the embodiment, the projections 44 and 48 having a substantially square cross section are formed on the inner peripheral sides of the bent portions in the two U-shaped flow paths, but the cross sections are substantially quadrangular other than substantially square. It is also possible to form a protrusion having another shape such as a mold or a substantially circular shape.

In the separator 20 of the embodiment and its modification, the case where the bent portion has a U-shape is considered, but it is of course applicable to the case where the bent portion has another shape. Is.

Although the embodiments of the present invention have been described with reference to the embodiments, the present invention is not limited to the embodiments of the present invention, and various embodiments are possible without departing from the gist of the present invention. Of course, it can be implemented in.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a configuration of a separator 20 for a fuel cell that is an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an outline of the configuration of a unit cell when a polymer electrolyte fuel cell is constructed using the separator 20 of the example.

FIG. 3 is an explanatory view showing bent portion ribs 142a and 142b of a modified example.

FIG. 4 is an explanatory view showing bent portion ribs 242a and 242b of a modified example.

FIG. 5 is an explanatory diagram illustrating the configuration of a conventional separator 320.

[Explanation of symbols]

20,320 separator, 22 fuel gas introduction hole, 2
3 Fuel gas communication hole, 24 Fuel gas discharge hole, 26 Oxidizing gas introduction hole, 27 Oxidizing gas communication hole, 28 Oxidizing gas discharge hole, 30, 32 Cooling water hole, 34, 36, 38, 33
4,336,338 Flow path forming ribs, 40 protrusions, 42
a, 42b, 46, 142a, 142b, 242a, 2
42b Bent portion rib, 44, 48, 144, 244 Bent portion protrusion, 243 protrusion, 50 Electrolyte membrane, 52, 54
electrode.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Suzuki             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Soshin             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Mitsuetsu Hibino             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Toshiyuki Inagaki             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Katsuhiro Kajio             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Tsutomu Ochi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Mikio Wada             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Yuichi Yagami             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Haruhisa Niimi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F-term (reference) 5H026 AA06 CC04 CC10

Claims (6)

[Claims] 1. A partition wall between unit cells when the fuel cell stack is formed by stacking with the electrodes to form a fuel gas or oxidizing gas flow path in contact with the electrodes. A separator for a fuel cell, wherein the convex portion in a portion that changes the flow direction of the gas,
A fuel cell separator formed so as to limit diffusion of the gas toward the outer periphery. 2. A partition wall between unit cells when a fuel cell stack is formed by stacking with the electrodes and having a plurality of protrusions that contact the electrodes to form a flow path for fuel gas or oxidizing gas. A separator for a fuel cell, wherein at least a part of the convex portion on the outer peripheral side in a portion that changes the flow direction of the gas is integrally formed at least before and after a predetermined location along the flow direction of the gas. The fuel cell separator in which the convex portion on the inner peripheral side of the portion is discretely formed. 3. The separator for a fuel cell according to claim 2, wherein the part that changes the flow direction of the gas has a plurality of corners that change the flow direction, and the predetermined part is the plurality of corners. Corner for fuel cell separator. 4. The fuel cell separator according to claim 2, wherein the predetermined portion is a portion that changes the flow direction of the gas. 5. The separator for a fuel cell according to claim 2, wherein the convex portion on the outer peripheral side of the portion that changes the flow direction of the gas has a narrower channel groove toward the downstream side. A formed fuel cell separator. 6. The separator for a fuel cell according to claim 2, wherein the convex portion on the inner peripheral side of the portion that changes the flow direction of the gas has a substantially circular shape or a substantially square shape in cross section. A separator for a fuel cell formed on.