JP2005071734A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of improving a gas flow coming round to a portion directly under the projecting part of a diffusion layer, and capable of maintaining a gas flow velocity in the straight portion or the bent portion of a passage. <P>SOLUTION: (1) This fuel cell is equipped with a separator 18 having a plurality of projecting parts 29 in the gas passage, and a groove 31 is provided on the top face of the projecting part 29. (2) The groove 31 is set up so that a collecting part 30 made by dividing the top face of the projecting part by the groove in the intra-surface direction have a uniform area. (3) The depth of the groove 31 is not less than an amount of a diffusion layer crushed when the diffusion layer is pushed by the collecting part 30. (4) The groove 31 has a first groove 31a and a second groove 31b obliquely intersecting to it. (5) The groove 31 is tilted in a direction along gas flow flowing a bent portion in the bent portion of the gas passage. (6) The groove 31 comprises a portion having a low step which is provided in a long land, and the area of the collecting part in the long land is made almost equal to the area of the collecting part in a short land. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell, and more particularly, to a structure of a contact portion between a convex portion of a separator and a diffusion layer.

  A solid polymer electrolyte fuel cell is composed of a laminate of a membrane-electrode assembly (MEA) and a separator (however, the lamination direction may be arbitrary). The membrane-electrode assembly includes an electrolyte membrane composed of an ion exchange membrane, an electrode composed of a catalyst layer disposed on one surface of the electrolyte membrane (anode, fuel electrode), and an electrode composed of a catalyst layer disposed on the other surface of the electrolyte membrane ( Cathode, air electrode). Between the membrane-electrode assembly and the separator, diffusion layers are provided on the anode side and the cathode side, respectively. In the separator, a fuel gas passage for supplying fuel gas (hydrogen) to the anode is formed, and an oxidizing gas passage for supplying oxidizing gas (oxygen, usually air) to the cathode. The separator is also formed with a refrigerant channel for flowing a refrigerant (usually cooling water). A cell is formed by stacking a membrane-electrode assembly and a separator, a module is formed from at least one cell, a module is stacked to form a cell stack, and terminals, insulators, end plates are formed at both ends of the cell stack in the cell stacking direction. The cell stack is clamped in the cell stacking direction and fixed with fastening members (for example, tension plates), bolts, and nuts extending in the cell stacking direction to form a stack.

  In each cell, a reaction for converting hydrogen into hydrogen ions (protons) and electrons is performed on the anode side, and the hydrogen ions move through the electrolyte membrane to the cathode side. On the cathode side, oxygen, hydrogen ions, and electrons (neighboring MEA) Next, the following reaction is performed to generate water from electrons generated at the anode of the first electrode through the separator or electrons generated at the anode of the cell at one end in the cell stacking direction through the external circuit to the cathode of the other cell.

Anode side: H ₂ → 2H ⁺ + 2e ⁻
Cathode side: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O
Japanese Patent Application Laid-Open No. 2001-143725 discloses a separator having a plurality of convex portions that are in contact with and in conduction with a diffusion layer in a gas flow path having a straight portion and a bent portion.
However, gas wrap-around is poor at the portion immediately below the convex portion of the diffusion layer, which is pressed by each convex portion of the separator, and the fuel cell performance is deteriorated. In order to improve the flow of gas to the portion immediately below the convex portion of the diffusion layer, in the fuel cell of Japanese Patent Application Laid-Open No. 2001-143725, the area of the top surface (current collector) of the convex portion is made small and uniform. Yes. However, when the top surface of the convex portion is made small and uniform, the straight portion of the uniform flow path has a short land instead of a long land in the gas flow direction, and the gas flow has a short land facing surface. The gas flow is hindered, the gas flow rate is lowered, the gas contact of the electrode per unit time is lowered, and the power generation efficiency is lowered. Further, in the bending of the flow path, the convex portions are arranged regardless of the gas flow direction in order to keep the surface pressure constant, which causes a decrease in the gas flow velocity.
JP 2001-143725 A

  The problem to be solved by the present invention is that in the conventional convex structure of a fuel cell, the gas wraparound property to the portion immediately below the convex part of the diffusion layer and the maintenance of the gas flow rate in the straight part or the bent part of the flow path are as follows. The problem is that they are not compatible.

  An object of the present invention is to provide a fuel cell that can improve the gas wrapping property to the portion immediately below the convex portion of the diffusion layer and can maintain the gas flow rate in the straight portion or the bent portion of the flow path. .

The present invention for solving the above problems and achieving the above object is as follows.
(1) It is configured by laminating a plurality of single cells, and the single cell includes a pair of electrodes sandwiching an electrolyte, a separator having a gas flow path and a plurality of convex portions in the gas flow path, and the electrodes. A diffusion layer provided between the separator and a groove on the top surface of the convex portion for flowing a gas to a portion pressed by the top surface of the convex portion of the diffusion layer. Fuel cell provided.
(2) The groove on the top surface of the convex portion is set so that the current collecting portion formed by dividing the top surface of the convex portion in the in-plane direction by the groove has a substantially uniform area (1) Fuel cell.
(3) The depth of the groove is equal to or greater than the amount by which the diffusion layer is crushed when the diffusion layer is pushed by the current collector, and is smaller than the depth of the gas flow path of the separator (2) The fuel cell as described.
(4) The groove has a first groove extending in the same direction as the gas flow in the gas flow path, and a second groove extending in a direction intersecting the first groove, and the second groove is The fuel cell according to (1), wherein the fuel cell is provided so as to cross obliquely with respect to the first groove.
(5) The groove has a first groove extending in the same direction as the gas flow in the gas flow path, and the first groove flows through the bent portion in the bent portion of the gas flow path of the separator. The fuel cell according to (1), wherein the fuel cell is inclined in a direction along the gas flow.
(6) The convex portion includes a short land provided in a bent portion of the gas flow path and a long land provided in a straight portion of the gas flow path, and the groove is provided in the long land. The groove is cut into the long land so that the area of the current collecting part of the long land is substantially equal to the area of the current collecting part of the short land by the groove comprising the low part of the step. The fuel cell according to (1).

According to the fuel cell of the above (1), since the groove is provided in the portion pressed by the top surface of the diffusion layer on the top surface of the convex portion, the gas flows through this groove, Gas wraps around the portion pressed by the convex top surface of the diffusion layer, and the power generation performance of the fuel cell is improved. Also, the depth of the groove provided on the convex portion is set appropriately, for example, the depth of the groove is made smaller than the height of the convex portion, and the convex portion is elongated in the gas flow direction in the straight flow path, etc. Thus, the gas flowing through the gas flow path can be guided by the convex portion to maintain the gas flow rate, the gas contact amount of the electrode per unit time can be maintained, and the power generation efficiency can be maintained well.
According to the fuel cell of the above (2), since the grooves are set so that a plurality of current collecting portions formed by dividing the top surface of the convex portion in the in-plane direction by the grooves have a substantially uniform area, The surface pressure at which the portion pushes the diffusion layer is made uniform, and the surface pressure applied to the electrolyte membrane can be made uniform. As a result, compared to the case where the surface pressure varies, the entire membrane is used better and power generation performance is improved, and the problem that the membrane is damaged and the durability is lowered at a portion where the surface pressure is high can be eliminated. .
According to the fuel cell of (3) above, since the depth of the groove is equal to or greater than the amount by which the diffusion layer is crushed when the diffusion layer is pressed by the current collector, the diffusion pressed by the convex portion by the stack fastening force Even if the layer portion is crushed, the gas can still enter the groove, and power generation in that portion is maintained. In addition, since the depth of the groove is smaller than the depth of the gas flow path of the separator, even if the convex portion is a long land in the straight flow path, the convex portion still remains in the groove forming portion, It can be guided to maintain the gas flow rate.

According to the fuel cell of (4), the groove has a first groove extending in the same direction as the gas flow, and a second groove extending in a direction intersecting the first groove, and the second groove is Since the first groove is provided so as to be oblique to the first groove, the discharge of water generated in the current collector is improved. The generated water in the first groove is pushed out by the gas entering the first groove, and the generated water in the oblique second groove is pushed out by the gas entering the second groove from the first groove and protruded. It is drawn out by the gas flowing on the side of the part.
According to the fuel cell of (5), the groove has the first groove extending in the same direction as the gas flow in the gas flow path, and the first groove is at the bent portion of the gas flow path of the separator. Since it is inclined in the direction along the gas flow flowing through the bent portion, the flow path pressure loss is small over the entire length of the gas flow path including the bent portion, and the power generation efficiency can be improved. In addition, since the gas flow in the bent portion of the gas flow path can be maintained satisfactorily and the gas contact amount of the electrode per unit time can be maintained large, the power generation efficiency can be improved.
According to the fuel cell of the above (6), the groove is formed by a groove provided in the long land of the flow path straight portion, and the area of each current collecting portion of the long land is reduced by the groove. Since the surface pressure of each current collecting portion of the long land and the surface pressure of the current collecting portion of the short land are substantially uniform, and the protruding surface pressure is eliminated, it is applied to the electrolyte membrane. Damage can be reduced. As a result, the durability of the fuel cell can be improved.

Below, the fuel cell of this invention is demonstrated with reference to FIGS. 1 to 3 show Embodiment 1 of the present invention, FIGS. 4 to 7 show Embodiment 2 of the present invention, FIG. 8 shows Embodiment 3 of the present invention, and FIGS. 9 and 10 show the present invention. Example 4 is shown, and FIGS. 11 and 12 show Example 5 of the present invention. FIG. 13 is commonly applicable to any of the embodiments of the present invention.
Components common to any embodiment of the present invention are labeled with the same reference numerals throughout all embodiments of the present invention.

First, a configuration common to all the embodiments of the present invention will be described with reference to FIGS. 2, 3, and 13, for example.
The fuel cell of the present invention is a solid polymer electrolyte fuel cell 10. The fuel cell 10 is mounted on, for example, a fuel cell vehicle. However, it may be used other than an automobile.

As shown in FIGS. 2, 3, and 13, the solid polymer electrolyte fuel cell 10 includes a laminate of a membrane-electrode assembly (MEA) and a separator 18. The stacking direction is arbitrary. The membrane-electrode assembly includes an electrolyte membrane 11 made of an ion exchange membrane, an electrode (anode, fuel electrode) 14 having a catalyst layer 12 disposed on one surface of the electrolyte membrane, and a catalyst disposed on the other surface of the electrolyte membrane 11. It comprises an electrode (cathode, air electrode) 17 having a layer 15. Between the membrane-electrode assembly and the separator 18, diffusion layers 13 and 16 for diffusing gas are provided on the anode side and the cathode side, respectively.
The membrane-electrode assembly and the separator 18 are overlapped to form a cell 19, a module is formed from at least one cell, the modules are stacked to form a cell stack, and terminals 20 and insulators are formed at both ends of the cell stack in the cell stacking direction. 21, end plate 22 is arranged, the cell stack is clamped in the cell stacking direction, and is fixed with a fastening member (for example, tension plate 24) extending in the cell stacking direction outside the cell stack, bolts and nuts 25, The stack 23 is configured.

The separator 18 is made of carbon, metal, metal and resin, or resin imparted with conductivity, or a combination thereof.
The separator 18 is formed with a fuel gas flow path 27 for supplying fuel gas (hydrogen) to the anode 14 and an oxidizing gas flow path 28 for supplying oxidizing gas (oxygen, usually air) to the cathode 17. Is formed. In addition, a coolant channel (not shown) for flowing a coolant (usually cooling water) is also formed on the surface of the separator 18 opposite to the gas channels 27 and 28. The refrigerant flow path is provided for each cell or for each of a plurality of cells (for example, for each module). The gas flow passages 27 and 28 are formed of concave portions formed in the separator 18, and a convex portion 29 described later is formed in a striped manner at the bottom of the concave portion, and gas flows into a space between the convex portions 29.

  As shown in FIG. 3, the fuel gas channel 27 includes a gas inlet 27a, a gas outlet 27b, one or more bent portions (folded portions) 27c, the bent portions 27c, or the bent portions 27c and the gas inlet 27a or gas. It has a plurality of straight portions 27d connecting the outlets 27b. Similarly, the oxidizing gas channel 28 connects the gas inlet 28a, the gas outlet 28b, one or more bent portions (folded portions) 28c, the bent portions 28c or between the bent portions 28c, and the gas inlet 28a or the gas outlet 28b. It has a plurality of straight portions 28d. Between the adjacent straight portions 27d and 28d, rib portions 27e and 28e for separating the adjacent straight portions 27d and 28d are provided.

The separator 18 is formed with a plurality of convex portions 29 projecting from the bottom surfaces of the gas flow paths 27 and 28 toward the electrodes 14 and 17.
Among the convex portions 29, the convex portions at the bent portions 27c and 28c of the gas flow path extend short in the gas flow direction, for example, are approximately square-shaped (however, not limited to the square, but circular, elliptical, etc. It may be a short land. Further, the convex portions on the straight portions 27d and 28d of the gas flow path may be formed of long lands extending substantially in the gas flow direction, for example, a substantially rectangular shape (but not limited to a rectangle). Or short land).

Among the plurality of convex portions 29, at least some of the convex portions (may be all convex portions), a groove 31 is provided at the top of the convex portion 29. The groove 31 may be provided only on the convex portion 29 of the fuel gas flow path 27, or may be provided only on the convex portion 29 of the oxidizing gas flow path 28, or the fuel gas flow path 27 and the oxidizing gas flow path. 28 may be provided on the convex portions 29 of both the flow paths. The groove 31 allows gas to flow through the portion of the diffusion layers 13 and 16 that is pressed by the top surface of the convex portion 29, and also supplies gas to the portions of the electrodes 14 and 17 directly below the convex portion 29. The groove 31 also serves as a gas flow guide by cutting in the gas flow direction. In this sense, the “groove” 31 may be referred to as a “guide”. Further, the groove 31 also serves as drainage from the contact portion of the convex portion 29 with the diffusion layers 13 and 16.
Each convex part 26 is in contact with the diffusion layers 14 and 17 at the top, except for the groove 31 in the convex part in which the groove 31 is formed, and is electrically connected to the diffusion layers 14 and 17. Forming. Here, the “current collector” 30 refers to a portion of the top surface of the convex portion 26 excluding the groove 31. When the top part of the convex part 29 is divided | segmented into the some current collection part 30 by the groove | channel 31, the one convex part 29 has the some current collection part 30 in the top part. When the top portion is not divided by the groove portion 31, one convex portion 29 has one current collecting portion 30 on the top portion.

  The groove 31 on the top surface of the convex portion 29 is set so that the current collecting portion 30 formed by dividing the top surface of the convex portion 29 in the in-plane direction has a substantially uniform area. Since the current collector 30 has a substantially uniform area, the surface pressure (pressing load per unit area) at which the current collector 30 presses the diffusion layers 13 and 16 becomes substantially uniform. When the convex portion 29 is a long land, a large surface pressure may be exerted compared to the case of a short land, and the variation in the surface pressure of the current collector 30 is large, but the area of the current collector 30 is substantially reduced by the groove 31. By making it uniform, the surface pressure of the current collector 30 becomes substantially uniform.

The depth of the groove 31 is equal to or greater than the amount by which the diffusion layers 13 and 16 are crushed when the diffusion layers 13 and 16 are pushed by the current collector 30, and the depths (convex portions) of the gas flow paths 27 and 28 of the separator 18. It is also smaller than 29).
By setting the depth of the groove 31 to be equal to or greater than the collapse amount of the diffusion layers 13 and 16, the groove 31 remains even when the diffusion layers 13 and 16 are pushed by the current collector 30, so that Circulate the gas.
Further, since the depth of the groove 31 is smaller than the height of the convex portion 29 of the separator 18, the root of the convex portion 29 remains even in the portion where the groove 31 exists, and the side surface of the base of the convex portion 29 is the gas flow path. 27 and 28 are guided to maintain the flow velocity in the gas flow direction. On the other hand, only by reducing the area of the conventional striped convex part without providing the groove 31, a part of the gas enters between the convex parts in the gas flow direction and hits the surface of the opposing convex part. Therefore, the convex portion has a large flow resistance, and the flow velocity in the gas flow direction is easily weakened.

Next, operations and effects of the components common to all the embodiments of the present invention will be described.
Since the groove 31 is provided on the top surface of the convex portion 29 in the portion pressed by the top surface of the convex portions 29 of the diffusion layers 13 and 16, the gas flows through the groove 31, whereby the diffusion layer 13, The gas wraps around the portion pressed by the top surface of the 16 convex portions 29. As a result, the power generation performance of the fuel cell is improved.
Further, by setting the depth of the groove 31 provided in the convex portion 29 appropriately (for example, by making the depth of the groove 31 smaller than the height of the convex portion 29), the straight flow path Then, the gas flowing through the gas flow passages 27 and 28 can be guided by the convex portion 29 by elongating the convex portion 29 in the gas flow direction, and the gas flow rate can be kept large. As a result, the gas contact amount of the electrodes 14 and 17 per unit time can be maintained, and the power generation efficiency can be maintained well.

  In addition, since the grooves 31 are set so that a plurality of current collecting portions 30 formed by dividing the top surface of the convex portion 29 in the in-plane direction by the grooves 31 have a substantially uniform area over the entire current collecting portions, the current collecting portions The surface pressure at which 30 presses the diffusion layers 13 and 16 is made uniform, and the surface pressure applied to the electrolyte membrane 11 can be made uniform. As a result, compared with the case where the surface pressure varies, the gas is supplied to the entire region of the membrane, so that the entire membrane is used well, power generation performance is improved, and the membrane 11 is damaged at a portion where the surface pressure is high. The problem that the durability of the fuel cell 10 is reduced can also be solved.

Since the depth of the groove 31 is equal to or greater than the amount by which the diffusion layers 13 and 16 are crushed when the diffusion layers 13 and 16 are pressed by the current collector 30, the diffusion layer portion pressed by the convex portion 29 by the stack fastening force Even if the gas is crushed, the gas can still enter the groove 31, and the power generation in that portion is maintained.
Further, since the depth of the groove 31 is smaller than the height of the convex portion 29, even if the convex portion is a straight land and a long land, the root of the convex portion 29 still remains in the formation portion of the groove 31, The gas can be guided to maintain the gas flow rate.

Next, parts specific to each embodiment of the present invention will be described.
In the first embodiment of the present invention, as shown in FIGS. 1 to 3, the bent portions 27c and 28c and the straight portions 27d and 28d are the same in at least one of the gas flow channels 27 and 28. A convex portion 29 having a shape (for example, square in plan view) is formed, and each convex portion 29 has at least one first groove 31a and at least one second groove 31b orthogonal thereto. It is cut. In the example of FIGS. 1 and 2, the first groove 31a is one, the second groove 31b is one, and the cross groove 31 is cut. The space between the convex portions constitutes a flow path through which gas flows. The depth of the groove 31 is smaller than the height of the convex portion 29.
The effect | action and effect of Example 1 of this invention are that the wraparound of the gas to the diffusion layer part right under a convex part and the drainage of the part are ensured, and can maintain a gas flow rate favorably.

In Example 2 of the present invention, as shown in FIGS. 4 to 7, a convex portion 31 is formed in at least one of the gas flow channels 27, 28, and the convex portions 27c, 28c are convex. The shape of the portion 31 is a short land (for example, a square in plan view), and the shape of the convex portion 31 in the straight portions 27d and 28d is a long land extending long in the gas flow direction (for example, the long side is a gas flow in plan view). Rectangle extending in the direction). At least one first groove 31a and at least one second groove 31b (the same number as the first grooves 31a) perpendicular to the first groove 31a are cut in the convex portion 29 of the short land. In the example of FIGS. 1 and 2, the first groove 31a is one, the second groove 31b is one, and the cross groove 31 is cut. The long land convex portion 29 has at least one first groove 31a parallel to the gas flow direction and at least one second groove 31b perpendicular to the first groove 31a (a number greater than the first groove 31a). is there. In the example of FIGS. 1 and 2, the first groove 31a is one, the second groove 31b is three, and the groove 31 is cut. The space between the convex portions constitutes a flow path through which gas flows. The depth of the groove 31 is smaller than the height of the convex portion 29.
The operation and effect of the second embodiment of the present invention are as follows. The gas wraps around the diffusion layer portion immediately below the convex portion and the drainage of the portion is ensured, and the gas flow rate is good (better than the first embodiment). It can be done. The short land collector 31 and the long land collector 31 have substantially the same area and uniform surface pressure. Conventionally, the durability of the film 11 immediately below the long land has been reduced due to variations in the surface pressure of the long land. However, in Example 2 of the present invention, the durability of the film immediately below the long land is lower than that of the film immediately below the short land. The durability is improved.

In Example 3 of the present invention, as shown in FIG. 8, a convex portion 31 is formed in at least one of the gas flow paths 27 and 28. The shape of the convex portion 31 in the straight portions 27d and 28d is a long land extending long in the gas flow direction. The long land protrusion 29 has at least one first groove 31a parallel to the gas flow direction and at least one second groove 31b obliquely intersecting with the first groove 31a (a larger number than the first groove 31a). It is. In the example of FIGS. 1 and 2, the first groove 31a is one, the second groove 31b is four grooves 31 on one side of the first groove 31a, and eight grooves 31 are cut on both sides.
With regard to the operation and effect of the third embodiment of the present invention, the second groove 31b is provided so as to cross obliquely with respect to the first groove 31a. Become. The generated water in the first groove 31a is extruded in the gas flow direction by the gas that has entered the first groove 31a, and the generated water in the oblique second groove 31b is changed from the first groove 31a to the second groove 31b. While being pushed out by the gas entering, it is drawn out by the gas flow flowing on the side surface of the convex portion 29. By improving the drainage, the contact of the electrode with the gas is less likely to be hindered by the generated water, the flooding is suppressed, and the power generation performance particularly in the downstream area of the oxidizing gas flow is improved.

In Example 4 of the present invention, as shown in FIGS. 9 and 10, the gas flow paths 27, 28 have bent portions (folded portions) 27 c, 28 c, and convex portions 31 are formed in the flow passages of the portions. Is formed. The shape of the convex portion 31 in the bent portions 27c and 28c is a short land, for example, a square (in plan view) having vertical and horizontal sides extending in parallel with the vertical and horizontal sides of the separator.
The groove 31 includes a first groove 31a extending in the same direction as the gas flow in the gas flow path (the second groove is not provided in the illustrated example), and the first groove 31a includes the gas flow path 27, The 28 bent portions 27c and 28c are inclined in a direction along the gas flow flowing through the bent portions 27c and 28c. Regarding the operation and effect of the fourth embodiment of the present invention, the first groove 31a is inclined in the direction along the gas flow flowing through the bent portions 27c and 28c in the bent portions 27c and 28c. The groove 31a serves as a gas flow guide to reduce the pressure loss. As a result, the flow passage pressure loss is small over the entire length of the gas flow passages 27 and 28 including the bent portions 27c and 28c, and the power generation efficiency can be improved. In addition, since the gas flow in the bent portions 27c and 28c of the gas flow paths 27 and 28 can be maintained satisfactorily and the gas contact amount of the electrode per unit time can be maintained large, the power generation efficiency can be improved.

In the fifth embodiment of the present invention, as shown in FIGS. 11 and 12, the convex portion 29 includes a short land provided at a bent portion of the gas flow paths 27 and 28, and a straight portion of the gas flow paths 27 and 28. And the groove 31 is formed of a low portion of the step provided in the long land, and the groove formed of the low portion of the step allows the area of the current collector 30 of the long land to be reduced. The groove 31 is cut into a long land so as to be approximately equal to the area of the current collector 30. The groove 31 is not cut in the convex portion 29 of the short land, the groove 31 is cut only in the convex portion 29 of the long land, and the groove 31 is a second groove extending in a direction orthogonal to the gas flow direction. It consists only of 31b. The width of the second groove 31b is wider than that of the other embodiments and has substantially the same width as that of the current collector 30. The second groove 31b extends between the two side surfaces of the long land.
Regarding the operation and effect of the fifth embodiment of the present invention, the groove 31 makes the area of each current collecting part 30 of the long land substantially equal to the area of the current collecting part 30 of the short land of the flow path bending part. The surface pressure of each current collecting portion of the long land and the surface pressure of the current collecting portion 30 of the short land are substantially uniform, and the damage to the electrolyte membrane 11 can be reduced by eliminating the protruding surface pressure. As a result, the durability of the fuel cell 10 can be improved.

It is a perspective view of the convex part in the gas flow path of the separator of the fuel cell of Example 1 of this invention. It is sectional drawing of a part of single cell of the fuel cell of Example 1 of this invention. It is a front view of the separator of the fuel cell of Example 1 of the present invention. It is sectional drawing of a part of single cell of the fuel cell of Example 2 of this invention. It is a top view of the convex part in the straight part of the gas flow path of the separator of the fuel cell of Example 2 of this invention. It is a top view of the convex part in the bending part of the gas flow path of the separator of the fuel cell of Example 2 of this invention. It is a front view of the separator of the fuel cell of Example 2 of the present invention. It is a top view of the convex part in the straight part of the gas flow path of the separator of the fuel cell of Example 3 of this invention. It is a front view of the separator of the fuel cell of Example 4 of the present invention. It is a top view of the some convex part in the bending part of the gas flow path of the separator of the fuel cell of Example 4 of this invention. It is a top view of the convex part in the straight part of the gas flow path of the separator of the fuel cell of Example 5 of this invention. It is sectional drawing of the convex part in the straight part of the gas flow path of the separator of the fuel cell of Example 5 of this invention. It is a side view of a stack of fuel cells applicable to any embodiment of the present invention.

Explanation of symbols

10 (Solid Polymer Electrolyte Type) Fuel Cell 11 Electrolyte Membrane 12, 15 Catalyst Layer 13, 16 Diffusion Layer 14 Electrode (Anode, Fuel Electrode)
17 electrodes (cathode, air electrode)
18 Separator 19 Cell 20 Terminal 21 Insulator 22 End plate 23 Stack 24 Fastening member (tension plate)
25 Bolt 27 Fuel gas flow path 27a Gas inlet 27b Gas outlet 27c Bent part (folded part)
27d Straight part (step part)
27e Partition rib 28 Oxidizing gas flow path 28a Gas inlet 28b Gas outlet 28c Bent part (folded part)
28d Straight part (step part)
28e Partition rib 29 Convex part 30 Current collecting part 31 Groove 31a First groove 31b Second groove

Claims (6)

  A plurality of unit cells are stacked, and the unit cell includes a pair of electrodes sandwiching an electrolyte, a separator having a gas flow path and a plurality of protrusions in the gas flow path, the electrode and the separator. A fuel cell comprising a diffusion layer provided between the first and second protrusions, wherein the top surface of the projection is provided with a groove for flowing a gas in a portion pressed by the top surface of the projection of the diffusion layer. battery.   2. The fuel cell according to claim 1, wherein the groove on the top surface of the convex portion is set so that a current collecting portion formed by dividing the top surface of the convex portion in the in-plane direction by the groove has a substantially uniform area. .   3. The fuel according to claim 2, wherein a depth of the groove is equal to or greater than an amount by which the diffusion layer is crushed when the diffusion layer is pushed by the current collector, and is smaller than a depth of the gas flow path of the separator. battery.   The groove has a first groove extending in the same direction as the gas flow of the gas flow path, and the first groove is a gas flow flowing through the bent portion in the bent portion of the gas flow path of the separator. The fuel cell according to claim 1, wherein the fuel cell is inclined in a direction along the direction.   The groove has a first groove extending in the same direction as the gas flow of the gas flow path and a second groove extending in a direction intersecting the first groove, and the second groove is defined as the first groove. The fuel cell according to claim 1, wherein the fuel cell is provided obliquely with respect to the groove.   The convex part has a short land provided at a bent part of the gas flow path and a long land provided at a straight part of the gas flow path, and the groove has a low step difference provided in the long land. The groove is cut into the long land so that the area of the current collecting portion of the long land is substantially equal to the area of the current collecting portion of the short land by the groove comprising the portion and the lower portion of the step. The fuel cell according to claim 1.

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