JP2021012852A - Separator for fuel cell - Google Patents

Abstract

To suppress a difference in drainage and gas diffusivity in the plane, and suppress a decrease in the uniformity of in-plane power generation in a separator for a fuel cell.SOLUTION: A separator for a fuel cell includes a reaction gas inlet for introducing reaction gas to the inside of the fuel cell, an off-gas outlet for discharging off-gas, and a plurality of wavy ribs for forming a plurality of gas channels connecting the reaction gas inlet and the off-gas outlet, and each of the ribs has a concave cross-sectional shape with an opening on the opposite side to a gas diffusion layer used in the fuel cell, projects in a direction away from the gas diffusion layer, and meanders along a flow path direction from the reaction gas inlet side to the off-gas outlet side in the separator for the fuel cell, and the wave-shaped amplitudes of the other plurality of ribs except the end rib which is the rib closest to the end of the separator for the fuel cell in the crossing direction intersecting the flow path direction from among the plurality of ribs are equal to each other, and the wave-shaped amplitude of the end rib is smaller than the wave-shaped amplitude of the plurality of other ribs.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a fuel cell separator.

The separator used in the fuel cell has a function of supplying a reaction gas to an adjacent gas diffusion layer in each fuel cell and discharging off-gas discharged from the gas diffusion layer to the outside of the fuel cell. In order to increase the contact area of the reaction gas and off-gas in the separator with respect to the power generation surface and improve the power generation performance, a plurality of corrugated ribs are lined up on the surface of the separator and a plurality of gas flows between the separator and the gas diffusion layer. Roads may be formed (see Patent Document 1). The reaction gas is directly supplied from the gas flow path to the portion of the gas diffusion layer facing the gas flow path, and the off-gas is directly discharged to the gas flow path. On the other hand, since the portion of the gas diffusion layer that does not face the gas flow path (hereinafter referred to as "gas flow path non-face-to-face portion") is in contact with the surface of the separator, the gas flow path non-face-to-face portion may be included. The reaction gas is diffused and supplied from the portion of the gas diffusion layer facing the gas flow path. Further, the off-gas discharged to the non-facing portion of the gas flow path diffuses in the gas diffusion layer and is discharged to the outside of the fuel cell from the portion facing the gas flow path.

Japanese Unexamined Patent Publication No. 2013-2010091

In the configuration in which the wave-shaped gas flow path is provided as described above, the gas flow path closest to the separator end in the intersecting direction intersecting the macroscopic flow direction of the gas flowing on the power generation surface (hereinafter, "endmost gas"). There is no gas flow path on the separator end side, as opposed to the "flow path"). Therefore, in the gas flow path non-facing portion existing on the separator end side of the end gas flow path, the reaction gas is supplied only from the end gas flow path, and the off gas is discharged only from the end gas flow path. Will be done. In such a configuration, due to the wavy shape of the terminal gas flow path, the distance to the gas flow path in the gas flow path non-facing portion existing on the separator end side of the terminal gas flow path is increased. It will vary greatly depending on the location. For this reason, in-plane differences in drainage and gas diffusivity may occur, leading to a decrease in the uniformity of in-plane power generation. Therefore, in a configuration in which a wave-shaped gas flow path is provided between the separator and the gas diffusion layer, a technique capable of suppressing a decrease in in-plane power generation uniformity is desired.

The present disclosure can be realized in the following forms.

According to one form of the present disclosure, a fuel cell separator used in a fuel cell is provided. The fuel cell separator includes a reaction gas inlet for introducing the reaction gas supplied to the fuel cell into the fuel cell, and an off-gas discharge port for discharging the off-gas to the outside of the fuel cell. The ribs are provided with a plurality of wavy ribs for forming a plurality of gas flow paths connecting the reaction gas inlet and the off-gas outlet, and each rib is provided with a gas diffusion layer used in the fuel cell. It has a concave cross-sectional shape with the facing side open, and while projecting in the direction away from the gas diffusion layer, it meanders along the flow path direction from the reaction gas inflow port side to the off gas discharge port side in the fuel cell separator. Of the plurality of ribs, the ribs of the other plurality of ribs except the end rib, which is the rib closest to the end of the fuel cell separator in the crossing direction intersecting the flow path direction. The wave-shaped amplitudes are equal to each other, and the wave-shaped amplitude of the endmost rib is smaller than the wave-shaped amplitude of the other plurality of ribs.

According to the fuel cell separator of this form, the wave-shaped amplitude of the endmost rib is smaller than the wave-shaped amplitude of the other plurality of ribs. Therefore, it is suppressed that the distance to the gas flow path in the non-face-to-face portion of the gas flow path existing on the end side in the crossing direction with respect to the end end gas flow path varies greatly depending on the location. Therefore, it is possible to suppress in-plane differences in drainage and gas diffusivity, and to suppress a decrease in uniformity of in-plane power generation.

It is a perspective view which shows the schematic structure of the fuel cell to which the separator for a fuel cell as one Embodiment of this disclosure is applied. It is an exploded perspective view which shows the schematic structure of the unit cell which comprises a fuel cell. It is a top view which looked at the separator in the −Z direction. It is a top view which shows the partial region of the gas diffusion layer on the anode side enlarged. It is a top view which enlarges and shows the partial region of the anode side gas diffusion layer in the single cell which used the separator of the comparative example. FIG. 5 is a plan view of the fuel cell separator of the second embodiment as viewed in the −Z direction. It is explanatory drawing which shows the relationship between the gas flow path part of the fuel cell separator of the comparative example, and the gas diffusion layer. FIG. 5 is an enlarged plan view schematically showing a gas flow path on the end side of the separator of the second embodiment in the intersecting direction. It is explanatory drawing which shows the relationship between the gas flow path part of the fuel cell separator of 2nd Embodiment, and a gas diffusion layer.

A. First Embodiment:
FIG. 1 is a perspective view showing a schematic configuration of a fuel cell 100 to which a fuel cell separator according to an embodiment of the present disclosure is applied. FIG. 2 is an exploded perspective view showing a schematic configuration of a unit cell 20 constituting the fuel cell 100. In FIG. 1, the X-axis, Y-axis, and Z-axis that are orthogonal to each other are shown. In the present embodiment, the + X direction and the −X direction are referred to as the X-axis direction. Similarly, the + Y direction and the −Y direction are referred to as the Y axis direction, and the + Z direction and the −Z direction are referred to as the Z axis direction. The X-axis, Y-axis, and Z-axis in other drawings described later correspond to the X-axis, Y-axis, and Z-axis of FIG.

The fuel cell 100 includes a large number of unit cells 20 (hereinafter, referred to as “fuel cell stack 20S”) stacked in the Z-axis direction. Each unit cell 20 is a polymer electrolyte fuel cell that generates electricity by being supplied with a fuel gas containing hydrogen and an oxidizing gas containing oxygen as reaction gases. As the fuel gas, for example, hydrogen gas may be used. Further, as the oxidation gas, for example, air may be used. The fuel cell stack 20S is sandwiched by a pair of end plates (not shown) in the stacking direction, that is, in the Z-axis direction, and is fastened in a state where a predetermined load is applied by a fastening member (not shown) extending in the stacking direction. Is housed in.

As shown in FIG. 1, a plurality of manifolds are formed inside the fuel cell 100 along the stacking direction. Specifically, an oxidation gas supply manifold 121, a cathode off gas discharge manifold 122, a fuel gas supply manifold 171, an anode off gas discharge manifold 172, a cooling water supply manifold 161 and a cooling water discharge manifold 162 are formed. The oxidation gas supply manifold 121 guides the oxidation gas to each unit cell 20. The cathode off gas discharge manifold 122 guides the cathode off gas discharged from each unit cell 20 to the outside of the fuel cell 100. The fuel gas supply manifold 171 guides the fuel gas to each unit cell 20. The anode off-gas discharge manifold 172 guides the anode-off gas discharged from each unit cell 20 to the outside of the fuel cell 100. The cooling water supply manifold 161 guides the cooling water to each unit cell 20. The cooling water discharge manifold 162 guides the cooling water discharged from each unit cell 20 to the outside of the fuel cell 100.

As shown in FIG. 2, the unit cell 20 includes a pair of fuel cell separators 80 that sandwich the membrane electrode gas diffusion layer joint body 18, the resin frame 82, and the membrane electrode gas diffusion layer joint body 18 and the resin frame 82. It includes 81. In the present embodiment, the fuel cell separators 80 and 81 are also simply referred to as "separators 80 and 81". Further, the membrane electrode gas diffusion layer assembly 18 is also referred to as MEGA (Membrane Electrode Gas diffusion layer assembly) 18 for convenience of explanation.

MEGA18 has a configuration in which a gas diffusion layer having gas permeability and electron conductivity is arranged on each surface of an anode side and a cathode side of a membrane electrode assembly (MEA) in which electrodes are arranged on both sides of an electrolyte membrane. Have. A gas diffusion layer may not be provided as long as the gas can be sufficiently diffused when the fuel gas and the oxide gas are supplied. On the contrary, in order to improve the gas diffusivity, a layer made of a porous body may be additionally provided in addition to the gas diffusion layer. MEGA can be obtained, for example, by sandwiching MEA (Membrane Electrode Assembly) between a pair of gas diffusion layers and press-bonding them.

The resin frame 82 is formed into a frame shape using a thermoplastic resin, and MEGA 18 is held in the central opening thereof. The resin frame 82 may be formed using, for example, a modified polyolefin such as modified polypropylene to which adhesiveness is imparted by introducing a functional group (for example, Admer manufactured by Mitsui Chemicals, Inc .; Admer is a registered trademark). The resin frame 82 is in contact with the separators 80 and 81 to ensure the gas sealability of the gas flow path on the anode side and the gas flow path on the cathode side.

The separators 80 and 81 serve to supply the reaction gas to the gas diffusion layer of the adjacent MEGA 18 and to discharge the off gas discharged from the gas diffusion layer to the outside of the fuel cell 100. The separators 80 and 81 are brought into close contact with the resin frame 82 so as to be in contact with the gas diffusion layer in MEGA18. The separator 80 forms a gas flow path with the gas diffusion layer on the anode side, and the separator 81 forms a gas flow path with the gas diffusion layer. The separators 80 and 81 are formed of a thin plate-like member having gas permeability and electron conductivity. For example, the separators 80 and 81 may be formed of a metal member such as foamed metal or metal mesh, or a carbon member such as carbon cloth or carbon paper.

The separators 80 and 81 and the resin frame 82 are formed with openings at the edges in the X-axis direction for forming the manifolds arranged inside the fuel cell 100 described above. Specifically, the separators 80 and 81 and the resin frame 82 have an oxide gas inflow port 12a forming the oxide gas supply manifold 121, a cathode off gas discharge port 12b forming the cathode off gas discharge manifold 122, and a fuel gas, respectively. The fuel gas inflow port 17a forming the supply manifold 171, the anode off gas discharge port 17b forming the anode off gas discharge manifold 172, the cooling water inflow port 16a forming the cooling water supply manifold 161 and the cooling water discharge manifold 162 are formed. A cooling water discharge port 16b is formed. The formation positions of the openings coincide with each other in the separators 80 and 81 and the resin frame 82. As a result, the separators 80 and 81 and the resin frame 82 are laminated, and the unit cells 20 are laminated to form the above-mentioned manifolds inside the fuel cell 100.

FIG. 3 is a plan view of the separator 80 as viewed in the −Z direction. On the surface of the separator 80 facing the MEGA 18 and the resin frame 82 (hereinafter referred to as the "power generation facing surface"), the portion of the MEGA 18 facing the −Z direction surface (hereinafter referred to as the "power generation surface") generates power. A rectangular recess 88 having a plan view shape that is substantially the same as the plan view shape of the surface is provided. Further, on the power generation facing surface of the separator 80, a gas inflow distribution section 89a, a gas discharge aggregation section 89b, and wave-shaped six ribs 83a to 83f are formed.

The gas inflow distribution unit 89a distributes the fuel gas supplied to the fuel gas inflow port 17a to the six ribs 83a to 83f. The gas inflow / distribution section 89a is composed of six linear ribs. Each rib has a concave cross-sectional shape with an opening on the side facing the resin frame 82, and extends linearly from the fuel gas inflow port 17a to one of the six ribs 83a to 83f. Therefore, in the state where the unit cell 20 is assembled, between the gas inflow / distribution unit 89a and the resin frame 82, the ribs 83a to 83f of the six ribs from the fuel gas inflow port 17a (gas flow paths 84a to 84f described later). A linear gas flow path is formed.

The gas discharge consolidating unit 89b collects the anode off gas discharged from the ribs 83a to 83f (the gas flow paths 84a to 84f described later) of the six rows and guides the anode off gas to the anode off gas discharge port 17b. The gas discharge consolidating unit 89b is composed of six linear ribs, similarly to the gas inflow and distribution unit 89a described above. Each rib has a concave cross-sectional shape with an opening on the side facing the resin frame 82, and extends linearly from one of the six ribs 83a to 83f to the anode off-gas discharge port 17b. Therefore, in the state where the unit cell 20 is assembled, the anode off gas discharge port 17b is connected between the gas discharge consolidating portion 89b and the resin frame 82 from the ribs 83a to 83f of the six rows (gas flow paths 84a to 84f described later). A linear gas flow path is formed.

The six ribs 83a to 83f have a concave cross-sectional shape in which the side facing the gas diffusion layer of MEGA 18 is open, and while projecting in the direction away from the gas diffusion layer (-Z direction), the anode from the fuel gas inflow port 17a side. It extends in a meandering manner along the direction toward the off-gas discharge port 17b (hereinafter, referred to as "flow path direction"). In the present embodiment, the “fuel gas inflow port 17a side” is the side on which the fuel gas inflow port 17a is formed along the X-axis direction when the fuel cell separator 80 is viewed in a plan view in the −Z direction, that is, , Means that it is on the + X direction side of the center. Further, the "anode off gas discharge port 17b side" is the side in which the anode off gas discharge port 17b is formed along the X-axis direction when the fuel cell separator 80 is viewed in a plan view in the −Z direction in the present embodiment. That is, it means that it is on the -X direction side of the center. Further, the above-mentioned "flow path direction" means a direction parallel to the X-axis direction. In the present embodiment, the widths of the six ribs 83a to 83f, in other words, the dimensions in the direction perpendicular to the flow direction of the gas passing through the ribs, are uniform at any position in the flow path direction. Further, in the present embodiment, the widths of the six ribs 83a to 83f are equal to each other.

As shown in FIG. 3, since the six ribs 83a to 83f are formed on the power generation facing surface in the fuel cell separator 80, the power generation surface is in the Y-axis direction in the state where the unit cell 20 is assembled. A plurality of wave-shaped gas channels meandering side by side are formed. Specifically, a gas flow path 84a is formed between the rib 83a and the power generation surface. Similarly, a gas flow path 84b between the rib 83b and the power generation surface, a gas flow path 84c between the rib 83c and the power generation surface, a gas flow path 84d between the rib 83d and the power generation surface, and a rib 83e. A gas flow path 84e is formed between the surface and the power generation surface, and a gas flow path 84f is formed between the rib 83f and the power generation surface. All of these six gas flow paths 84a to 84f connect the fuel gas inflow port 17a and the anode off-gas discharge port 17b via the gas inflow distribution section 89a and the gas discharge aggregation section 89b. The six gas flow paths 84a to 84f supply the fuel gas supplied from the fuel gas inflow port 17a to the MEGA 18, and guide the anode off gas discharged from the MEGA 18 to the anode off gas discharge port 17b. As described above, since the six ribs 83a to 83f meander in a waveform, the six gas flow paths 84a to 84f also meander in a waveform. As a result, the contact area of the reaction gas and the off-gas with respect to the power generation surface becomes larger than that of the linear gas flow path, and the power generation performance is improved.

As shown in FIG. 3, the six ribs 83a to 83f coincide with each other in the positions of the corrugated convex portions when viewed in the Y-axis direction (hereinafter, also referred to as “intersection direction”) orthogonal to the flow path direction. As shown above, they are arranged at equal intervals in the crossing direction. The amplitude of the wave shape at each rib 83a to 83f, that is, the dimension in the Y-axis direction is constant over the entire flow path direction. That is, taking the rib 83c as an example, from the end portion in the + X direction (that is, the connection portion with the gas inflow / distribution portion 89a) to the end portion in the −X direction (that is, the connection portion with the gas discharge aggregation portion 89b). The amplitude of the wave shape of the rib 83c is constant. However, in the present embodiment, of the six ribs 83a to 83f, the two ribs 83a and 83f closest to the end in the intersecting direction of the separator 80, that is, the end in the + Y direction and the end in the −Y direction ( The wave-shaped amplitude of the "most end ribs 83a and 83f") is smaller than the wave-shaped amplitude of the other four ribs 83b to 83e excluding the most end ribs 83a and 83f. In this embodiment, the amplitudes of the wave shapes of the four ribs 83b to 83e are equal to each other. Further, the amplitudes of the wave shapes of the two end ribs 83a and 83f are equal to each other. Here, in the present embodiment, the amplitude of the wave shape in each of the ribs 83a to 83f is the width direction (Y-axis direction) from the end in the + X direction to the end in the −X direction in each of the ribs 83a to 83f. It means the amplitude of the curve of the virtual waveform connecting the center positions.

FIG. 4 is an enlarged plan view showing a partial region Ar10 of the anode-side gas diffusion layer. The partial region Ar10 is a region of the anode-side gas diffusion layer in MEGA 18 facing the partial region Ar1 of the separator 80 shown in FIG. As shown in FIG. 4, in the MEGA 18, the partial region Ar10 includes three gas flow path facing portions 181a to 181c and three gas flow path non-facing portions 182a to 182c.

The gas flow path facing portion 181a faces the rib 83a and faces the gas flow path 84a. Similarly, the gas flow path facing portion 181b faces the rib 83b and faces the gas flow path 84b. Further, the gas flow path facing portion 181c faces the rib 83c and faces the gas flow path 84c. Fuel gas is directly supplied from the gas flow paths 84a to 84c to these three gas flow path facing portions 181a to 181c. Further, off-gas is directly discharged to the gas flow paths 84a to 84c from the three gas flow path facing portions 181a to 181c.

The gas flow path non-facing portion 182a does not face the gas flow path. Specifically, the + Y direction end of the gas flow path non-facing portion 182a corresponds to the + Y direction end 18E of the MEGA 18, and the −Y direction end is in contact with the gas flow path facing portion 181a. .. Further, the gas flow path non-face-to-face portion 182b is sandwiched between the gas flow path facing portion 181a and the gas flow path facing portion 181b in the Y-axis direction and does not face the gas flow path. Similarly, the gas flow path non-face-to-face portion 182c is sandwiched between the gas flow path facing portion 181b and the gas flow path facing portion 181c in the Y-axis direction and does not face the gas flow path. These three gas flow path non-facing portions 182a to 182c are in contact with portions on the power generation facing surface of the separator 80 where the ribs 83a to 83f are not formed.

Fuel gas is indirectly supplied to the gas flow path non-face-to-face portion 182b from two adjacent gas flow paths 84a and 84b via the two gas flow path facing portions 181a and 181b. Further, the anode off gas discharged from the gas flow path non-facing portion 182b is indirectly discharged to the two gas flow paths 84a and 84b via the two adjacent gas flow path facing portions 181a and 181b. Similarly, fuel gas is indirectly supplied to the gas flow path non-face-to-face portion 182c from two adjacent gas flow paths 84b and 84c via the two gas flow path facing portions 181b and 181c. Further, the anode off gas discharged from the gas flow path non-facing portion 182c is indirectly discharged to the two gas flow paths 84b and 84c via the two adjacent gas flow path facing portions 181b and 181c.

On the other hand, there are no ribs in the + Y direction with respect to the gas flow path non-facing portion 182a, and therefore there is no gas flow path. Therefore, fuel gas is indirectly supplied to the gas flow path non-face-to-face portion 182a from one adjacent gas flow path 84a via one gas flow path facing portion 181a. Further, the anode off gas discharged from the gas flow path non-facing portion 182a is indirectly discharged to one gas flow path 84a via one adjacent gas flow path facing portion 181a.

Here, the distances from the gas flow path at the two positions P11 and P12 in the gas flow path non-face-to-face portion 182c are examined. The total distance of the distance L111 from the gas flow path 84b to the position P11, the distance L112 from the gas flow path 84c to the position P11, the distance L121 from the gas flow path 84b to the position P12, and the distance P12 from the gas flow path 84c to the position P12. The total distance to and from L122 is approximately equal to each other. This is because, as described above, the positions of the convex portions of the ribs 83b and 83c forming the two gas flow paths 84b and 84c that sandwich the gas flow path non-face-to-face portion 182c coincide with each other in the X-axis direction and have a wavy shape. This is because the amplitudes of are equal to each other. Such a relationship is not limited to the two positions P11 and P12 illustrated in FIG. 4, but also holds at any other two positions. Therefore, the gas diffusivity and drainage property in the gas flow path non-face-to-face portion 182c are substantially uniform in the plane.

On the other hand, the distances from the gas flow path at the two positions P1 and P2 in the gas flow path non-facing portion 182a are examined. As described above, the fuel gas is supplied to the gas flow path non-facing portion 182a only from the gas flow path 84a. The distance L1 from the gas flow path 84a to the position P1 and the distance L2 from the gas flow path 84a to the position P2 are different from each other. More specifically, the distance L1 is larger than the distance L2. The positions of the two positions P1 and P2 along the Y-axis direction are equal to each other. This difference in distance from the gas flow path is due to the fact that the end of the gas flow path non-face-to-face portion 182a in the −Y direction is wavy, whereas the end in the + Y direction is linear. To do. Due to such a difference in distance from the gas flow path, more fuel gas can be supplied at position P2 than at position P1. Further, at position P2, more anode off gas can be discharged as compared with position P1. However, in the present embodiment, the wave-shaped amplitude of the rib 83a is configured to be smaller than the wave-shaped amplitude of the ribs 83b and 83c, in other words, the wave-shaped curve of the rib 83a is formed by the rib 83b. , The difference between the distances L1 and L2 is suppressed to be small because the curve is gentler than the wave-shaped curve of 83c.

FIG. 5 is an enlarged plan view showing a partial region of the anode-side gas diffusion layer in a single cell using the separator of the comparative example. The partial region Ar20 is a region of the anode-side gas diffusion layer of MEGA of Comparative Example, and is a region at substantially the same position as the partial region Ar10 shown in FIG.

The separator of the comparative example is different from the separators 80 and 81 of the first embodiment in that the amplitude of the wave shape of the endmost rib is equal to the amplitude of the wave shape of the other ribs. In FIG. 5, the gas flow path facing portion 181 g facing the endmost rib is shown by a solid line, and the gas flow path facing portion 181a facing the rib 83a, which is the end end rib of the first embodiment, is shown by a broken line. The two positions P21 and P22 shown in the gas flow path non-face-to-face portion 182 g sandwiched between the gas flow path facing portion 181 g and the end portion 18E have relative positions in MEGA that are not facing the gas flow path shown in FIG. It is the same position as the two positions P1 and P2 in the portion 182a. As shown in FIG. 5, the distance L21 from the gas flow path 84a (gas flow path facing portion 181 g) to the position P21 is larger than the distance L1 shown in FIG. 4 described above. On the other hand, the distance L22 from the gas flow path 84a (gas flow path facing portion 181 g) to the position P22 is smaller than the distance L2 shown in FIG. 4 described above. Therefore, the difference between the distance L21 and the distance L22 is large. Therefore, in the comparative example, the gas diffusivity and drainage property in the gas flow path non-face-to-face portion 182 g differ greatly depending on the location, and the in-plane power generation uniformity and drainage uniformity are low. On the other hand, in the fuel cell 100 using the fuel cell separator 80 of the first embodiment, there is an in-plane difference (non-uniformity) in the distance from the gas flow path 84a in the gas flow path non-facing portion 182a. It has been reduced, and the decrease in in-plane power generation uniformity and drainage uniformity is suppressed. It should be noted that such an effect is not limited to the gas flow path non-facing portion 182a, but is sandwiched in the Y-axis direction between the gas flow path facing portion facing the gas flow path 84f and the end portion of the MEGA 18 in the −Y direction. It also plays in the non-face-to-face part of the gas flow path.

The configuration of the separator 81 is almost the same as the configuration of the separator 80 described above. That is, the separator 81 on the cathode side is also provided with a gas inflow distribution section, six ribs, and a gas discharge aggregation section. Therefore, the effect caused by the structure of the separator 80 described above, that is, the in-plane difference (non-uniformity) in the distance from the end gas flow path is reduced, and the in-plane power generation uniformity and drainage uniformity are reduced. The decrease in gas is suppressed. In addition, the description of the detailed configuration of the separator 81 will be omitted.

The fuel gas inlet 17a in the separator 80 and the oxidation gas inlet 12a in the separator 81 correspond to the reaction gas inlet in the present disclosure. Further, the anode off-gas discharge port 17b in the separator 80 and the cathode off-gas discharge port 12b in the separator 81 correspond to the off-gas discharge port in the present disclosure.

According to the fuel cell separators 80 and 81 of the first embodiment described above, the fuel cell separators 80 and 81 used in the fuel cell 100 are provided. The fuel cell separators 80 and 81 have a fuel gas inlet 17a and an oxide gas inlet 12a corresponding to a reaction gas inlet for introducing the reaction gas supplied to the fuel cell 100 into the fuel cell 100. A plurality of gas flow paths connecting the anode off-gas discharge port 17b and the cathode off-gas discharge port 12b, which correspond to the off-gas discharge port for discharging the off-gas to the outside of the fuel cell 100, and the reaction gas inflow port and the off-gas discharge port. It is provided with a plurality of wavy ribs 83a to 83f for forming, and each rib has a concave cross-sectional shape with an opening facing the gas diffusion layer used in the fuel cell 100, and is separated from the gas diffusion layer. While protruding in the direction, the fuel cell separators 80 and 81 meander and extend along the flow path direction from the reaction gas inlet side to the off-gas discharge port side, and the flow path among the plurality of ribs 83a to 83f. The wave-shaped amplitudes of the plurality of ribs 83b, 83c, 83d, 83e excluding the most extreme ribs 83a, 83f, which are the ribs closest to the ends of the fuel cell separators 80, 81 in the crossing direction intersecting the directions, are Equal to each other, the wave-shaped amplitude of the terminalmost ribs 83a, 83f is smaller than the wave-shaped amplitude of the other plurality of ribs 83b, 83c, 83d, 83e. Therefore, it is suppressed that the distance to the gas flow path 84a in the gas flow path non-face-to-face portion 182a existing on the end side in the crossing direction with respect to the endmost gas flow path varies greatly depending on the location. Therefore, it is possible to suppress in-plane differences in drainage and gas diffusivity, and to suppress a decrease in uniformity of in-plane power generation.

B. Second embodiment:
In the fuel cell separator 80a of the second embodiment, the wave-shaped amplitude of the plurality of ribs formed in the intersecting direction of the power generation surface gradually decreases from the central portion to the end side in the intersecting direction. It differs from the fuel cell separator 80 of the first embodiment in that it is used. Further, in the fuel cell separator 80a of the second embodiment, the width of the rib, in other words, the dimension in the direction orthogonal to the flow direction of the gas passing through the rib is uniform when viewed in the X-axis direction in each rib. It is different from the fuel cell separator 80 of the first embodiment in that it is not. Since the configuration of the fuel cell separator 80a of the second embodiment other than these is the same as that of the fuel cell separator 80 of the first embodiment, the same reference numerals are given and the description thereof will be omitted. ..

FIG. 6 is a plan view of the fuel cell separator 80a of the second embodiment as viewed in the −Z direction. Wave-shaped six ribs 43a to 43f are formed on the power generation facing surface of the separator 80a. In the present embodiment, of the six ribs 43a to 43f, the wave-shaped amplitudes of the ribs 43c and 43d formed in the central portion of the separator 80a in the intersecting direction are the largest. As it approaches the end in the crossing direction, the amplitude of the wave shape of the rib gradually decreases, and the amplitude of the wave shape of the outermost ribs 43a and 43f becomes the smallest. In this embodiment, the wave-shaped amplitudes of the two end ribs 43a and 43f are equal to each other. Therefore, also in the separator 80a in the second embodiment, it is suppressed that the distance to the gas flow path in the gas flow path non-face-to-face portion existing on the end side in the crossing direction with respect to the end end gas flow path varies greatly depending on the location. To.

FIG. 7 is an explanatory diagram showing the relationship between the gas flow path portions R30a and R30b of the fuel cell separator of the comparative example and the gas diffusion layer G30. The left side in FIG. 7 represents a flow path portion formed from the waveform of the rib on the end side in the crossing direction (the same position as Ar1 in FIG. 3) as in FIGS. 3 and 6. Further, the right side in FIG. 7 schematically shows a cross-sectional view when the separator is cut in the intersecting direction.

The wave-shaped amplitude of the ribs in the fuel cell separator of the comparative example has a structure in which the amplitude gradually decreases from the central portion in the crossing direction toward the end portion side. Further, the width of the flow path portion formed by the wave shape of the ribs in the fuel cell separator of the comparative example in the intersecting direction is constant when viewed in the flow path direction.

As shown on the left side in FIG. 7, the gas flow path portion R30a is formed on the end side of the gas flow path portion R30b, and the gas flow path portion R30a is gentler than the gas flow path portion R30b. It is a curve. Further, the flow path widths of the flow path portions R30a and R30b are constant over the entire flow path direction (X-axis direction). Specifically, the flow path width of the flow path portion R30a is the flow path width L30a over the entire X-axis direction. The flow path width of the flow path portion R30b is the flow path width L30b over the entire X-axis direction.

As shown in FIG. 7, of the gas flow path non-facing portions sandwiched between the gas flow path portion R30a and the gas flow path portion R30b, the gas diffusion layer corresponding to the portion of the separator that is convex toward the center of the power generation surface. The width L301 in the intersecting direction of the contact surface G301 (hereinafter referred to as “GDL”) is the power generation surface of the separator among the gas flow path non-facing portions sandwiched between the gas flow path portion R30a and the gas flow path portion R30b. It is larger than the width L302 in the intersecting direction of the GDL contact surface G302 corresponding to the portion convex toward the end side.

Therefore, in the comparative example, the distance to the gas flow path in the non-face-to-face portion of the gas flow path varies greatly depending on the location. Specifically, the total distance from any of the GDL contact surfaces G301 to the gas flow paths R30a and R30b and the gas flow path from any of the GDL contact surfaces G302. The total distance to parts R30a and R30b varies greatly from place to place. Therefore, when viewed in the direction of the flow path in the separator of the comparative example, the location of the non-face-to-face portion of the gas flow path may cause non-uniformity in the power generation surface of gas diffusivity to GDL and drainage from GDL. ..

In contrast to the above comparative example, in the separator 80a of the second embodiment, the in-plane non-uniformity of gas diffusivity to GDL and drainage from GDL is suppressed by adjusting the width of each rib. Hereinafter, a detailed description will be given with reference to FIGS. 8 and 9.

FIG. 8 is a plan view schematically showing an enlarged gas flow path on the end side of the separator of the second embodiment in the intersecting direction. In FIG. 8, each of the three gas flow paths non-facing portions sandwiched between the gas flow paths R1 to R3 and the outer edge of the recess 88, which will be described later, is convex toward the central portion in the crossing direction (-Y direction in FIG. 8). The convex portion and the convex portion having a convex shape in the crossing direction end side (+ Y direction in FIG. 8) are represented by different hatches for convenience of explanation.

In the present embodiment, the widths of the ribs 43a to 43c forming the gas flow paths R1 to R3 are not constant in the intersecting direction. Specifically, in each of the ribs 43a to 43c, the width in the intersecting direction (Y direction) of the convex portion convex in the −Y direction is the intersection direction of the convex portion in which the rib is convex in the + Y direction. Greater than width. Further, in the convex portion of each of the ribs 43a to 43c, which is convex in the central portion side in the crossing direction (-Y direction in FIG. 8), the curved portion on the end side in the crossing direction is formed at the same position in the X-axis direction. The amplitude of the side surface extending along the X-axis direction (hereinafter referred to as "end side side surface") is the curved side surface on the central portion side in the crossing direction and extending along the X-axis direction (hereinafter referred to as "end side side surface"). Hereinafter, it is referred to as “central side surface”), which is smaller than the amplitude. On the other hand, in the convex portion of each rib 43a to 43c that is convex in the crossing direction end side (+ Y direction in FIG. 8), the amplitude of the end side side surface is the same at the same position in the X-axis direction. It is almost equal to the amplitude of the side surface on the central side. The width of each of the ribs 43a to 43c and the degree of amplitude of the curved side surface of each of the ribs 43a to 43c are determined so that the width L501 and the width L502 are substantially the same in FIG. There is.

The flow path width depends on the shape of the rib. That is, if the width of the rib in the crossing direction is large, the flow path width in the crossing direction is also large, and if the width of the rib in the crossing direction is small, the flow path width in the crossing direction is also small. As described above, in each of the ribs 43a to 43c, the width in the crossing direction of the convex portion convex toward the central portion in the crossing direction is larger than the width in the crossing direction of the convex portion convex toward the end side in the crossing direction. Also, in the convex part that is convex toward the center in the intersection direction, the amplitude of the side surface of the end is smaller than the amplitude of the side surface of the center at the same position in the X-axis direction, and the end in the intersection direction. In the convex portion having a convex shape on the portion side, at the same position in the X-axis direction, the amplitude of the side surface of the end portion and the amplitude of the side surface of the central portion are substantially equal, so that in the present embodiment, as shown in FIG. Of the region formed by the flow path R1 formed by the endmost rib and the outer edge (end on the + Y direction side) of the recess 88 in the separator, the area of the convex portion S1 in the −Y direction and the + Y direction. The difference from the area of the convex portion T1 is smaller than that in which the width of the rib is constant in the intersecting direction. Similarly, the difference between the area of the convex portion S2 in the −Y direction and the area of the convex portion T2 in the + Y direction among the gas flow path non-corresponding portions sandwiched between the flow paths R1 and the flow path R2 is rib. The width of the is smaller than that of a constant structure in the crossing direction. Further, among the gas flow path non-corresponding parts sandwiched between the flow paths R2 and the flow path R3, the difference between the area of the convex portion S3 in the −Y direction and the area of the convex portion T3 in the + Y direction is the rib. The width is smaller than that of a constant width in the crossing direction. With such a configuration, the in-plane difference in gas diffusivity to the GDL is reduced depending on the location of the non-facing portion of the gas flow path.

FIG. 9 is an explanatory diagram showing the relationship between the gas flow path portions 44a and 44b of the fuel cell separator 80a of the second embodiment and the gas diffusion layer G50. FIG. 9 is a diagram corresponding to FIG. 7 of the comparative example.

As described above, the amplitude of the wave shape of the ribs in the fuel cell separator 80a of the second embodiment has a structure in which the amplitude gradually decreases from the central portion in the crossing direction toward the end portion side. Further, in the gas flow paths 44a and 44b, the width in the crossing direction of the convex portion convex toward the central portion in the crossing direction is larger than the width in the crossing direction of the convex portion convex toward the end side in the crossing direction, respectively. Also, in the convex part that is convex toward the center in the intersection direction, the amplitude of the side surface of the end is smaller than the amplitude of the side surface of the center at the same position in the X-axis direction, and the end in the intersection direction. In the convex portion having a convex shape on the portion side, the amplitude of the side surface of the end portion and the amplitude of the side surface of the central portion are substantially equal at the same position in the X-axis direction. With such a configuration, the width L501 in the crossing direction of the gas flow path non-face-to-face portion sandwiched by the convex portions that are convex toward the center portion in the crossing direction of the two gas flow path portions 44a and 44b is the end portion in the crossing direction. It is substantially the same as the width L502 in the intersecting direction of the gas flow path non-face-to-face portion sandwiched by the convex portion that is convex to the side.

Therefore, in the second embodiment, the distance to the gas flow path in the non-facing portion of the gas flow path does not differ greatly depending on the location. Specifically, for example, the total distance from any of the GDL contact surfaces G501 to the gas flow paths 44a1 and 44b1 and the gas from any of the GDL contact surfaces G502. The total distance to the flow paths 44a2 and 44b2 does not vary significantly from place to place. Therefore, in the separator 80a of the second embodiment, it is suppressed that the location of the non-facing portion of the gas flow path causes a difference in the gas diffusivity to the GDL and the drainage property from the GDL in the power generation surface.

According to the fuel cell separator 80a of the second embodiment described above, it has the same effect as the separator 80 of the first embodiment. In addition, since the widths of the ribs 43a to 43f in the intersecting direction of the gas non-face-to-face portions are configured to be substantially constant over the entire flow path direction (X-axis direction), the gas flow path non-face-to-face portions are formed. The distance to the gas flow path in the section does not differ greatly depending on the location. Therefore, in the separator 80a of the second embodiment, it is suppressed that the location of the non-facing portion of the gas flow path causes a difference in the gas diffusivity to the GDL and the drainage property from the GDL in the power generation surface, and the in-plane power generation is performed. It is possible to suppress a decrease in uniformity.

C. Other embodiments:
(C1) The amplitude of the wave shape of the ribs in the fuel cell separator 80a of the second embodiment has a structure in which the amplitude gradually decreases from the central portion in the crossing direction toward the end portion side. Further, the width of the convex portion in the crossing direction, which is convex toward the central portion in the crossing direction, is larger than the width in the crossing direction of the convex portion, which is convex toward the end side in the crossing direction. In the convex portion having a convex shape, the amplitude of the side surface of the end portion is smaller than the amplitude of the side surface of the central portion at the same position in the X-axis direction, and in the convex portion having a convex shape toward the end side in the crossing direction. , At the same position in the X-axis direction, the amplitude of the side surface of the end portion and the amplitude of the side surface of the central portion are substantially equal. On the other hand, the shape of the rib may be any shape such that the width between the flow paths, that is, the width in the crossing direction of the gas flow path non-face-to-face portions sandwiched between the flow paths is constant.

(C2) In the above embodiment, the ribs in the separator are arranged in the intersecting direction at equal intervals, but they may not be arranged at equal intervals.

(C3) In the above embodiment, the number of ribs in the separator is 6, but the number may be any number of 4 or more.

(C4) In the fuel cell separator 80a of the second embodiment, it is assumed that one cycle of the waveform of the flow path in the X-axis direction is constant, but it does not have to be constant. Specifically, in FIG. 8, the length of the flow path in the X-axis direction, which is one cycle of R1 to R3, is constant, but it does not have to be constant.

The present disclosure is not limited to the above-described embodiment, and can be realized by various configurations within a range not deviating from the gist thereof. For example, the technical features of the embodiments corresponding to the technical features in each embodiment described in the column of the outline of the invention are for solving a part or all of the above-mentioned problems, or a part of the above-mentioned effects. Or, in order to achieve all of them, it is possible to replace or combine them as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be appropriately deleted.

12a ... Oxidation gas inlet, 12b ... Cathode off gas outlet, 16a ... Cooling water inlet, 16b ... Cooling water outlet, 17a ... Fuel gas inlet, 17b ... Anode off gas outlet, 18 ... Membrane electrode gas diffusion layer junction , 18E ... end, 20 ... unit cell, 20S ... fuel cell stack, 44a, 44a1, 44a2 ... gas flow path, 80, 80a, 81 ... separator, 82 ... resin frame, 43a, 43b, 43c, 43d, 43e , 43f, 83a, 83b, 83c, 83d, 83e, 83f ... Rib, 44a, 44b, 44c, 44d, 44e, 44f, 84a, 84b, 84c, 84d, 84e, 84f ... Gas flow path, 88 ... Recess, 89a ... Gas inflow distribution unit, 89b ... Gas discharge aggregation unit, 100 ... Fuel cell, 121 ... Oxidation gas supply manifold, 122 ... Cathode off gas discharge manifold, 161 ... Cooling water supply manifold, 162 ... Cooling water discharge manifold, 171 ... Fuel gas Supply manifold, 172 ... Anode off gas discharge manifold, 181a, 181b, 181c, 181g ... Gas flow path facing portion, 182a, 182b, 182c, 182g ... Gas flow path non-facing portion, Ar1, Ar10, Ar20 ... Partial region, G30, G50 ... Gas diffusion layer, G301, G302, G501, G502 ... GDL contact surface, L1, L111, L112, L121, L122, L2, L21, L22 ... Distance, L301, L302, L501, L502 ... Width, L30a, L30b ... Flow path width, P1, P11, P12, P2, P21, P22 ... Position, R1, R2, R3 ... Flow path, R30a, R30b ... Flow path, S1, S2, S3, T1, T2, T3 ... Convex Department

Claims (1)

A fuel cell separator used in fuel cells.
A reaction gas inlet for introducing the reaction gas supplied to the fuel cell into the inside of the fuel cell, and
An off-gas discharge port for discharging off-gas to the outside of the fuel cell,
A wave-shaped plurality of ribs for forming a plurality of gas flow paths connecting the reaction gas inlet and the off-gas outlet,
With
Each rib has a concave cross-sectional shape with an opening on the side facing the gas diffusion layer used in the fuel cell, and while projecting in a direction away from the gas diffusion layer, from the reaction gas inflow port side of the fuel cell separator. It is extended in a meandering manner along the flow path direction toward the off-gas discharge port side.
Among the plurality of ribs, the wave-shaped amplitudes of the plurality of ribs other than the end rib, which is the rib closest to the end of the fuel cell separator in the crossing direction intersecting the flow path direction, are Equal to each other
The wavy amplitude of the farthest rib is smaller than the wavy amplitude of the other plurality of ribs.
Separator for fuel cells.

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