JP2012018883A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new technique contributive to improvement in water drainage in a fuel cell having an interdigital branch channel having closed flow channel ends.SOLUTION: A fuel cell 10 has gas inflow channels 48in and gas outflow channels 48out arranged alternately. In the gas inflow channel 48in, weir portions 49a extending obliquely from the surface side of a gas diffusion layer 24 to the upstream side, and recesses 49b facing them are provided. Since the weir portions 49a dam air flowing through the gas inflow channel 48in, the water carried by the air is stored in the weir portions 49a and enters the gas outflow channel 48out contiguous to the gas inflow channel 48in by penetrating the gas diffusion layer 24.

Description

  The present invention relates to a fuel cell.

  A fuel cell generates electricity by an electrochemical reaction between fuel and its oxidant, for example, hydrogen and oxygen. This fuel cell generally includes a membrane electrode assembly (power generator) in which anode and cathode electrodes are formed on both membrane surfaces of an electrolyte membrane (for example, a solid polymer membrane having proton conductivity), and a gas diffusion layer interposed. And then sandwiched between separators.

  In such a fuel cell, various proposals have been made to improve the cell performance by improving the gas utilization rate. As one of them, the configuration of the flow path of the fuel gas or the oxidizing gas is a configuration in which a plurality of flow paths that are branched in a comb shape and closed at the end of the flow path are alternately arranged so that the closed sides are staggered. It has been proposed (for example, Patent Document 1). In the fuel cell having such a flow path configuration, the supplied gas first flows into the flow path whose gas inlet side is opened and whose end is closed. The gas that has flowed into the flow path passes through the gas diffusion layer where the ribs between the flow paths abut due to the blockage of the flow path ends, and flows into the adjacent flow path. Since this adjacent flow path is closed on the gas inlet side and released on the gas outlet side contrary to the previous flow path, the gas flowing into the adjacent flow path is along the surface of the gas diffusion layer. Since the gas is discharged while flowing, the efficiency of the gas spreading throughout the gas diffusion layer is increased, and the gas utilization rate is improved over the entire electrode surface.

JP-A-11-16591 JP 2004-296198 A

  In the fuel cell having the comb-like branching channels alternately closing the channel ends as described above, although improvement in cell performance can be expected by improving the gas utilization rate, the following problems Came to be pointed out. On the cathode side, water is generated by an electrochemical reaction, and the generated water is carried by the gas flowing through the flow path and stored at the closed flow path end. The generated water stored at the end of the flow path passes through the gas diffusion layer near the end of the flow path in the same manner as the gas, reaches the adjacent flow path, and is discharged outside the battery. Since the movement of the generated water is caused by the difference in static pressure between adjacent flow paths, the generated water movement in the gas diffusion layer takes a certain amount of time. For this reason, in the vicinity of the end of the flow path where all the generated water accumulates and the generated water moves, the gas diffusion is inhibited by the generated water in the gas diffusion layer in the range where the generated water enters, and this is effective. The power generation area will be reduced.

  The present invention has been made in order to solve at least a part of the above-described conventional problems, and in a fuel cell having a comb-like branched flow path with the flow path end closed, the water drainage is improved. The purpose is to provide a new method that contributes to

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the following configuration is adopted.

[Application 1: Fuel cell]
A membrane electrode assembly in which electrodes are formed on both membrane surfaces of the electrolyte membrane, a gas diffusion layer provided on at least one electrode surface of the membrane electrode assembly, and a reaction that is subjected to an electrochemical reaction in the gas diffusion layer A fuel cell having a gas flow path for supplying gas,
The gas flow path is
A plurality of gas inflow passages extending from the side of the gas supply manifold for supplying the reaction gas, blocked at the end of the flow passage, and flowing the reaction gas flowing in from the gas supply manifold along the surface of the gas diffusion layer; ,
A gas that extends side by side from the gas discharge manifold side for gas discharge and that is blocked at the end of the flow path and that has passed through the gas diffusion layer from the gas flow path, receives the gas A plurality of gas outflow passages for flowing out to the gas discharge manifold while flowing along the surface of the gas diffusion layer,
The gas inflow channel is
A dam section located on the surface side of the gas diffusion layer to block the gas, and a dam portion for converting the gas flow direction to the side away from the surface of the gas diffusion layer;
Receiving the gas converted into the flow on the side away from the surface of the gas diffusion layer by the dam part, and converting the gas in the flow path over the dam part and flowing toward the surface side of the gas diffusion layer And having a part.

  In the fuel cell having the above configuration, the reaction gas flowing in from the gas supply manifold is allowed to enter a plurality of gas inflow channels. Since the flow channel is closed at the end, the reaction gas that has entered the gas inflow channel passes through the gas diffusion layer and enters the adjacent gas outflow channel. The reaction gas entering the gas outflow passage in this manner flows out from the gas discharge manifold while flowing along the surface of the gas diffusion layer. The reaction gas is supplied to the membrane electrode assembly through the gas diffusion layer when passing through the gas inflow channel, through the gas diffusion layer, and when passing through the gas outflow channel.

  In a fuel cell having the above-described configuration, water (for example, produced water) that has entered the gas inflow channel is discharged as follows along with the gas supply described above. The gas flowing along the gas inflow channel is blocked by the dam portion of the gas inflow channel, flows in a direction away from the surface of the gas diffusion layer, and thereafter is received by the in-channel conversion unit. After flowing over the weir part, it flows toward the surface of the gas diffusion layer. The water carried along the gas inflow channel by the flowing gas collides with the weir when the gas is blocked in the weir, accumulates in the weir, and closes the end of the blocked channel (hereinafter referred to as channel blockage). It also accumulates at the end. Then, the water accumulated in the weir part and the closed end of the channel passes through the gas diffusion layer from the gas inflow channel and enters the adjacent gas outflow channel due to the static pressure difference between the adjacent channels. It is transported along the flow path and discharged. That is, in the fuel cell having the above-described configuration, the water storage locations (hereinafter referred to as water storage locations) are dispersed in the flow passage closed end and the weir portion, so that The amount stored can be reduced. As a result, according to the fuel cell having the above-described configuration, it is possible to shorten the time required for water movement and improve the drainage performance associated therewith.

  The fuel cell described above can be configured as follows. For example, the damming surface on which the gas collides toward the upstream side of the gas flow can be inclined toward the upstream side so that the angle formed with the surface of the gas diffusion layer becomes an acute angle. In this way, the dam part forms an acute-angled so-called return region that covers the surface of the gas diffusion layer on the upstream side of the dam on the upstream side of the gas flow. For this reason, the dam part reliably stores water in the return region between the damming surface and the surface of the gas diffusion layer, and prevents the stored water from flowing into the downstream flow path. Therefore, according to said aspect, dispersion | distribution of a water storage location becomes reliable and it is useful for shortening of the time which water movement requires, and the improvement of the drainage property accompanying this.

  Further, the in-channel conversion portion may be opened toward the dam portion as a recess in the channel formed on the side of the back wall of the channel facing the surface of the gas diffusion layer. In this way, the gas that has been converted into the flow away from the surface of the gas diffusion layer by the weir part, and then the gas flow over the gas weir part and the gas flow toward the surface side of the gas diffusion layer The effectiveness of the conversion can be increased. And since the flow-path area from the upstream of a weir part to downstream can be made substantially uniform, after stabilizing a gas flow, the above-mentioned time reduction and drainage improvement can be aimed at.

  And the said dam part and the said in-flow-path conversion part can be provided in the multiple places of the said gas inflow flow path. If it carries out like this, since the amount of the weir part which stores water will increase, dispersion | distribution of a water storage location will advance, and since the quantity of the water stored in each water storage location can also be reduced, the further drainage improvement can be aimed at.

  Further, the gas inflow channel and the gas outflow channel are adjacent to each other as a meandering path that meanders in the surface of the gas diffusion layer, and the gas inflow channel is further connected to the weir portion and the channel. A conversion unit may be provided in the meandering path. In this way, in the meandering portion where the gas flows along the meandering path, the gas flow advances from the gas inflow passage through the gas diffusion layer and enters the adjacent gas outflow passage due to the change in the gas flow. Therefore, the movement of water on the gas from the gas inflow channel to the gas outflow channel side is also promoted. Therefore, the drainage can be further improved.

It is a cross-sectional schematic diagram showing the schematic structure of the single cell 15 which comprises the fuel cell 10 as one Example of this invention. It is explanatory drawing which shows an example of the specific shape of the gas separator 26 by planar view. It is a schematic sectional drawing of the 3-3 line in FIG. FIG. 4 is a schematic cross-sectional view taken along line 4-4 in FIG. It is a schematic sectional drawing of line 5-5 in FIG. FIG. 6 is a schematic cross-sectional view taken along line 6-6 in FIG. It is explanatory drawing which shows an example of the mode of formation of the dam part 49a and the recess 49b in the gas inflow channel 48in. It is explanatory drawing for demonstrating the flow of the gas in the gas inflow channel 48in in association with the weir part 49a and the recess 49b. It is explanatory drawing which shows the modification of the recess 49b. It is explanatory drawing which shows another modification of the recess 49b. It is explanatory drawing which shows the other modification of the dam part 49a and the recess 49b. It is explanatory drawing which shows the modification which made the gas inflow flow path 48in and the gas outflow flow path 48out meander.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a single cell 15 constituting a fuel cell 10 as an embodiment of the present invention. The fuel cell 10 of the present embodiment has a stack structure in which a plurality of single cells 15 having the configuration shown in FIG. 1 are stacked. The fuel cell 10 of the present embodiment is a solid polymer fuel cell, but can be similarly applied to different types of fuel cells, for example, solid oxide fuel cells.

  The single cell 15 includes both electrodes of an anode 21 and a cathode 22 on both sides of the electrolyte membrane 20. The anode 21 and the cathode 22 are formed on both membrane surfaces of the electrolyte membrane 20 to form a membrane electrode assembly (MEA). In addition, the single cell 15 includes gas diffusion layers 23 and 24 and gas separators 25 and 26 that sandwich the electrolyte membrane 20 on which electrodes have been formed from both sides, and both gas diffusion layers are joined to corresponding electrodes. The gas separator 25 is provided with an in-cell fuel gas flow channel 47 for flowing a fuel gas containing hydrogen on the gas diffusion layer 23 side. The gas separator 26 includes an in-cell oxidizing gas flow channel 48 through which an oxidizing gas containing oxygen (air in this embodiment) flows, on the gas diffusion layer 24 side. Although not shown in FIG. 1, for example, an inter-cell refrigerant flow path through which a refrigerant flows can be formed between adjacent single cells 15.

  The electrolyte membrane 20 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good electrical conductivity in a wet state. The anode 21 and the cathode 22 include a catalyst (for example, platinum or a platinum alloy), and are formed by supporting these catalysts on a conductive carrier (for example, carbon particles). The gas diffusion layers 23 and 24 can be formed of a conductive member having gas permeability, such as carbon paper or carbon cloth. The gas separators 25 and 26 are made of a gas-impermeable conductive member, for example, a dense carbon made by compressing carbon and impermeable to gas, baked carbon, or a metal material such as stainless steel. The gas separators 25 and 26 are members that form the wall surfaces of the in-cell fuel gas flow path 47 and the in-cell oxidizing gas flow path 48 described above, and the surface has an uneven shape for forming the gas flow path. Is formed.

  Although not shown in FIG. 1, a plurality of holes are formed at predetermined positions in the vicinity of the outer peripheries of the gas separators 25 and 26. The plurality of holes overlap each other when the gas separators 25 and 26 are laminated together with other members and the fuel cell 10 is assembled, thereby forming a flow path that penetrates the fuel cell 10 in the lamination direction. That is, a manifold for supplying and discharging fuel gas, oxidizing gas, or refrigerant is formed with respect to the in-cell fuel gas channel 47, the in-cell oxidizing gas channel 48, or the inter-cell refrigerant channel.

  Next, the details of the in-cell oxidizing gas channel 48 in the gas separator 26 on the cathode 22 side will be described. 2 is an explanatory view showing an example of a specific shape of the gas separator 26 in plan view, FIG. 3 is a schematic sectional view taken along line 3-3 in FIG. 2, and FIG. 4 is a schematic sectional view taken along line 4-4 in FIG. 5 is a schematic sectional view taken along line 5-5 in FIG. 2, and FIG. 6 is a schematic sectional view taken along line 6-6 in FIG. In the following description, for the convenience of description, the long side direction of the rectangular shape formed by the gas separator 26 is referred to as a horizontal direction, and the rectangular short side direction is referred to as a vertical direction.

As shown in the drawing, the gas separator 26 includes holes 40 to 45 in the vicinity of the outer periphery along two sides in the vertical direction. The hole 40 forms a fuel gas supply manifold (indicated as H ₂ in in the figure), the hole 41 forms a refrigerant supply manifold (indicated as CLT in in the figure), and the hole 42 supplies oxidizing gas. A manifold is formed (indicated as O ₂ in in the figure), a hole 43 forms a refrigerant discharge manifold (indicated as CLT out in the figure), and a hole 44 forms an oxidizing gas discharge manifold (in the figure, O ₂ shows the out), the hole portion 45 forms a fuel gas discharge manifold (in the figure, indicated as H ₂ out). Since the gas separator 26 is on the cathode 22 side, the air (oxidizing gas) flowing into the cell from the oxidizing gas supply manifold in the hole 42 is a gas flow path described later formed by the gas separator 26. And is discharged from the oxidizing gas discharge manifold of the hole 44. Such gas supply is performed in each of the stacked single cells 15. In the gas separator 25 on the anode 21 side, the hydrogen gas (fuel gas) that has flowed into the cell from the fuel gas supply manifold in the hole 40 passes through the gas flow path formed by the gas separator 25 and passes through the hole. 45 is discharged from the fuel gas discharge manifold.

  The gas separator 26 shown in FIG. 2 has a substantially rectangular area formed in the middle thereof, in which an in-cell fuel gas flow path is formed and overlaps the cathode 22 and communicates with the hole 42 and the hole 44, and the power generation area 50. To do. The gas separator 26 is provided with streak-like gas flow paths (in-cell oxidizing gas flow paths 48) arranged alternately in the horizontal direction in the power generation region 50. That is, the gas separator 26 is provided with the inter-flow-path ribs 30 and the groove portions 32 alternately in the horizontal direction in the power generation region 50, and the respective groove portions 32 are alternately formed by the inlet-side blocking portions 34 and the outlet-side blocking portions 35. Block. In this case, both the closing portions on the inlet / outlet side may close the groove portion 32 with a member different from the rib 30 between the channels (for example, another member formed of ceramics, carbon, metal, resin or rubber). It is also possible to perform cutting or the like so that the groove portion 32 is alternately closed by the inlet side closing portion 34 and the outlet side closing portion 35. In order to reduce the contact resistance between the gas separator 26 and the gas diffusion layer 24, it is desirable that the inlet side blocking portion 34 and the outlet side blocking portion 35 be made of a conductive material.

  Both the above-mentioned closed portions close the groove portion 32 at the installation location, that is, at the end or end of the flow path. For this reason, the gas separator 26 includes a plurality of groove portions 32 that do not include the inlet side blocking portion 34 on the hole portion 42 side but have the outlet side blocking portion 35 on the hole portion 44 side. The gas supply manifold (hole 40) branches into a comb-like shape and is blocked at the end of the flow path, and the inflowed air flows into the gas inflow path 48in that flows along the surface of the gas diffusion layer 24 of the cathode 22. . On the other hand, the gas separator 26 includes a plurality of the gas separators 26 even in the groove portion 32 which includes the inlet side blocking portion 34 on the hole portion 42 side and does not have the outlet side blocking portion 35 on the hole portion 44 side. The plurality of grooves 32 are branched into comb teeth from the side of the gas discharge manifold (hole 44), closed at the channel ends, and gas outlet channels 48out arranged alternately with the gas inlet channels 48in. Become. That is, the single cell 15 has alternately the gas inflow channel 48in and the gas outflow channel 48out branched in a comb-teeth shape with the inter-channel rib 30 interposed therebetween. As shown in FIG. 5, the gas inflow channel 48in has a weir portion 49a inclined with respect to the gas flow direction indicated by an arrow in the figure and a recess 49b opposite to the weir portion 49a. The configuration of the location and the state of gas passage in both flow paths will be described later. In the gas outflow channel 48out, as shown in FIG. 6, such a weir and recess are not provided, and a simple channel starting from the inlet side blocking portion 34 is provided.

  Further, in the power generation region 50, the gas separator 26 includes a region between the end portions of the plurality of inter-channel ribs 30 and the hole portions 40 to 42, and an end portion and the hole portion 43 of the plurality of inter-channel ribs 30. In the region between ˜45, a plurality of convex portions 36 formed to be spaced apart from each other are provided. In the fuel cell 10, the plurality of convex portions 36 are in contact with the gas diffusion layer 24 and constitute part of the wall surface of the in-cell gas flow path. The air that has flowed into the in-cell fuel gas flow path from the gas supply manifold formed by the hole 42 is guided to the space formed between the convex portions 36 on the upstream side, and is distributed to the plurality of gas inflow paths 48in. The

  The air that has flowed into the gas inflow channel 48in is closed at the end thereof by the outlet side blocking portion 35. Therefore, as shown in FIG. 3, the gas inflow channel 48in and the gas outflow channel 48out Permeate through the gas diffusion layer 24 in a range where the inter-flow-path ribs 30 are in contact with each other and enter the adjacent gas outflow flow-path 48out. Since the gas outflow passage 48out is a simple passage as described above, the reaction gas that has entered the gas outflow passage 48out flows without resistance along the surface of the gas diffusion layer 24. Part 44). The air passes through the gas inflow passage 48in and passes through the gas diffusion layer 24 in the range where the inter-passage ribs 30 abut (hereinafter, the air permeation at this time is referred to as rib abutment location air permeation). And when passing through the gas outflow passage 48out, the gas is supplied to the MEA through the gas diffusion layer 24. This rib contact location air permeation occurs due to a static pressure difference between the adjacent gas inflow channel 48in and gas outflow channel 48out. Also on the anode 21 side, the above-described flow path configuration can be made in the gas separator 25.

  Next, the dam 49a and the recess 49b will be described. FIG. 7 is an explanatory view showing an example of the formation of the weir 49a and the recess 49b in the gas inflow channel 48in, and FIG. 8 relates the gas flow in the gas inflow channel 48in to the weir 49a and the recess 49b. It is explanatory drawing for demonstrating.

  As shown in FIG. 7, for example, the groove portions 32 are alternately formed in the gas separator 26, and the inlet end blocking portion 34 is attached to the groove portion 32 that becomes the gas outflow passage 48out to close the end portion of the flow passage. For the groove portion 32 to be the gas inflow channel 48in, a plurality of recesses 49b are formed in advance on the bottom surface of the groove portion, and a frame body 60 in which the weir portions 49a are incorporated in a ladder shape is attached to the groove portion opening recess 49c. In this case, the depth of the groove opening recess 49c and the size of the frame body 60 are the same, and the lower surface of the frame body 60 and the lower surface of the dam portion 49a in the figure are adjusted to be flush with each other. Further, the formation pitch of the plurality of recesses 49 b in the groove portion 32 and the formation pitch of the plurality of dam portions 49 a in the frame body 60 are the same. Therefore, as shown in FIG. 8, the gas separator 26 that has been fitted with the frame body 60 forms a gas inflow channel 48in so that the gas flows along the surface of the gas diffusion layer 24. After the lower surface of the portion 49a is brought into contact with the gas diffusion layer 24, the weir portion 49a and the recess 49b face each other.

  The weir portion 49a is a triangular wave-shaped convex body extending to the gas inflow channel 48in so as to rise from the surface of the gas diffusion layer 24, and blocks the gas (air) flowing through the gas inflow channel 48in. Further, the weir portion 49a converts the flow direction of the gas flowing through the gas inflow channel 48in to the side away from the surface of the gas diffusion layer 24, that is, the side of the recess 49b as shown in FIG. In addition, the weir portion 49a has an acute angle with the surface of the gas diffusion layer 24, which is the damming surface of the weir where the gas collides toward the upstream side of the gas (air) flow through the gas inflow channel 48in. Inclined toward the upstream side.

  As shown in FIGS. 7 and 8, the recess 49b is formed on the back wall side of the gas inflow channel 48in facing the surface of the gas diffusion layer 24 and is open toward the weir portion 49a. Has been. Then, as shown in FIG. 8, the recess 49b receives the gas converted into the flow away from the surface of the gas diffusion layer 24 by the dam portion 49a, and gets over the dam portion 49a. It flows toward the surface side of the gas diffusion layer 24 above.

  In the fuel cell 10 of this embodiment, as described above, the supply of air to the cathode 22 by the in-cell oxidizing gas channel 48 of the gas inflow channel 48in and the gas outflow channel 48out, and the in-cell fuel gas channel 47 In response to the supply of hydrogen to the anode 21, power is generated, and water is generated at the cathode 22 along with the power generation. This generated water enters the gas inflow channel 48in and the gas outflow channel 48out. In the fuel cell 10 of the present embodiment, this generated water is discharged as follows.

  As shown in FIGS. 5 and 7 to 8, the fuel cell 10 according to the present embodiment includes a plurality of weir portions 49 a and recesses 49 b facing the gas inflow channel 48 in, and gas flowing through the gas inflow channel 48 in. (Air) is once blocked by the weir portion 49a. The air thus dammed flows in a direction away from the surface of the gas diffusion layer 24, and thereafter, is received by the recess 49b and gets over the dam 49a and then on the surface side of the gas diffusion layer 24. It flows toward. The air blocking and the flow direction change are repeated at the positions where the weir portions 49a and the recesses 49b are installed. The generated water carried along the gas inflow channel 48in by the flowing air collides with the dam 49a when the gas (air) is dammed in the dam 49a and is stored in the dam 49a. Since the dynamic pressure of air conveyance is applied in the gas inflow channel 48in, the generated water remains stored in the weir portion 49a under the dynamic pressure, and the generated water carried to the air over the weir portion 49a is The gas is stored in the outlet side blocking portion 35 of the gas inflow channel 48in. The water accumulated in the respective weir portions 49a and the outlet side blocking portions 35 is diffused from the gas inflow channel 48in due to the static pressure difference between the gas inflow channel 48in and the gas outflow channel 48out on both sides thereof. It passes through the layer 24 and enters the gas outflow channel 48out on both sides thereof. Since the gas outflow passage 48out is a simple passage as shown in FIG. 6, the generated water that has entered the gas outflow passage 48out is carried to the air along the gas outflow passage 48out, and the fuel is discharged. The battery 10 is discharged.

  As described above, in the fuel cell 10 of the present embodiment, not only the generated water is stored in the outlet side blocking portion 35 but also the plurality of dam portions 49a extending from the surface side of the gas diffusion layer 24 to the gas inflow channel 48in. Is also distributed and stored, the amount of generated water stored in the outlet side blocking portion 35 and each weir portion 49a can be reduced. As a result, according to the fuel cell 10 of the present embodiment, the time required for water movement can be shortened and the drainage can be improved. In addition, since the amount of generated water stored in the outlet side blocking portion 35 and each dam portion 49a is small, water movement can be completed in a short time, so that the generated water stays in the gas diffusion layer 24 can be suppressed. As a result, battery performance can be maintained.

  Further, in the fuel cell 10 of the present embodiment, when the dam portion 49a is extended from the surface of the gas diffusion layer 24, the angle between the dam portion 49a and the damming surface of the dam that the gas collides with the surface of the gas diffusion layer 24 is used. Is inclined toward the upstream side of the flow of the gas inflow channel 48in so as to have an acute angle. For this reason, an acute angle so-called return region in which the upstream side surface of the dam covers the surface of the gas diffusion layer 24 can be formed at the base of the dam portion 49a (see FIG. 8). Therefore, in the fuel cell 10 of the present embodiment, The generated water can be reliably stored in the return region between the upstream surface of the weir portion 49a and the surface of the gas diffusion layer, and the stored generated water can be prevented from flowing into the downstream flow path. Therefore, according to the fuel cell 10 of the present embodiment, since the generated water can be dispersed and stored in the respective dam portions 49a, the effectiveness of shortening the time required for water movement and improving drainage can be improved. Can do.

  Further, in the fuel cell 10 of the present embodiment, a dynamic pressure that causes air conveyance along the gas inflow passage 48in is applied to the weir portion 49a inclined and extending to the gas inflow passage 48in as described above. For this reason, since the dynamic pressure for air conveyance is also made to act so that the generated water stored in the weir portion 49a can move through the gas diffusion layer 24 and move to the adjacent gas outflow passage 48out, the time required for water movement The effectiveness of shortening and improving drainage can be further increased.

  In addition, the fuel cell 10 of the present embodiment is provided with a recess 49b facing the weir 49a extending from the surface of the gas diffusion layer 24, and the recess 49b is opened toward the weir 49a. Therefore, according to the fuel cell 10 of the present embodiment, the dam portion 49a receives the gas (air) converted into the flow away from the surface of the gas diffusion layer 24, and the dam portion of the gas (air) thereafter. The effectiveness of overcoming 49a and converting the flow of gas toward the surface side of the gas diffusion layer 24 can be enhanced. Moreover, since the flow passage area from the upstream to the downstream of the weir portion 49a can be made almost uniform, according to the fuel cell 10 of the present embodiment having the recess 49b, the flow of gas (air) is stabilized, The above-described time reduction and drainage improvement can be achieved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and can be implemented in various modes without departing from the scope of the present invention. For example, in this embodiment, the air flow path (intra-cell oxidizing gas flow path 48) on the cathode 22 side has alternating comb-shaped branch flow paths with closed flow path ends, The inflow channel 48in is a channel having the weir portion 49a and the recess 49b facing each other, but the in-cell fuel gas channel 47 of the anode 21 is the same as the in-cell oxidizing gas channel 48. The gas inflow channel (hydrogen gas inflow channel) can be a channel having weir portions 49a and recesses 49b facing each other. When the hydrogen gas is supplied to the anode 21, the gas may be humidified, so that the water vapor added for humidification may become water droplets in the in-cell fuel gas flow channel 47. Then, in the same manner as described for the cathode 22, the water droplets are dispersed and stored in the closed portions at the end of the channel and the respective weir portions 49 a in the gas inflow channel (hydrogen gas inflow channel), and discharged. Therefore, drainage on the anode side can also be enhanced.

  Moreover, about the dam part 49a and the recess 49b, various deformation | transformation are possible, such as a mode of formation in a corresponding flow path, and a recess shape. FIG. 9 is an explanatory view showing a modification of the recess 49b, and FIG. 10 is an explanatory view showing another modification of the recess 49b. As shown in FIG. 9, in the gas separator 26 </ b> A of this modified example, the back wall surface (upper wall surface in the figure) of the gas inflow channel 48 in facing the surface of the gas diffusion layer 24 is a recess 49 b. Further, the gas separator 26B of the modification of FIG. 10 includes a concave portion 49b that is recessed in a spherical shape so as to face the weir portion 49a. Even in such a modified example, receiving the gas (air) converted into the flow away from the surface of the gas diffusion layer 24 by the weir portion 49a, and then overcoming the gas (air) weir portion 49a The gas flow toward the surface side of the gas diffusion layer 24 can be converted, and the above-described effects can be achieved.

  FIG. 11 is an explanatory view showing another modification of the weir portion 49a and the recess 49b. As shown in the figure, in the gas separator 26C of this modification, the weir portion 49a is a rectangular convex body extending upward from the surface of the gas diffusion layer 24, and a recess 49b facing the weir portion 49a is formed. Also, the recess 49b is recessed in a rectangular shape. Even in this modification, the above-described effects can be achieved.

  Further, although the in-cell oxidizing gas channel 48 (the gas inflow channel 48in and the gas outflow channel 48out) is a linear and adjacent channel, it can be modified as follows. FIG. 12 is an explanatory view showing a modification in which the gas inflow channel 48in and the gas outflow channel 48out are meandering trajectories. As shown in the figure, the gas separator 26D has a gas inflow channel 48in and a gas outflow channel 48out that overlap the surface of the gas diffusion layer 24 adjacent to each other as a meandering path meandering in the surface of the gas diffusion layer 24 in a triangular wave shape. As described above, the flow path ends are closed by the inlet side blocking portion 34 and the outlet side blocking portion 35 as described above. The gas inflow channel 48in has a plurality of dam portions 49a and recesses 49b facing the same as in the gas separator 26 of the embodiment described above. In this modified example, the weir portion 49a is provided on the long side of the meandering path and the cross section taken along the line XX in the figure is the same as the cross section shown in FIGS. Even in this modified example, the water (product water) carried by the gas flowing along the flow path (meandering path flow path) of the gas inflow flow path 48in as indicated by the arrow YA in the figure is the respective. Since dispersion storage is performed at the weir portion 49a, the above-described effects can be achieved. And this modification has the following advantages.

  Since the flowing gas as shown by the arrow YA in the figure collides with the rib 30A between the flow paths at the meandering location of the meandering locus and changes the direction of the flow, the generated water carried by this gas is also It collides with the inter-passage rib 30A and accumulates on the side of the meandering passage. Since the gas receives the dynamic pressure of air conveyance toward the meandering portion channel side surface in the direction indicated by the arrow YA, the gas permeates through the gas diffusion layer 24 below the inter-passage rib 30A that hits the meandering portion channel side surface. As shown by the arrow YB in the middle, it enters the side of the adjacent gas outflow channel 48out. Such gas permeation through the diffusion layer and entering the flow path causes the generated water stored on the side surface of the meandering portion flow path to enter the gas outflow path 48out. As a result, according to this modification, it is possible to further shorten the time required for water movement and further improve drainage. The meandering trajectory may be a curved meandering trajectory, a trajectory meandering into a rectangular wave shape, in addition to the triangular wave shape shown in the figure.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 15 ... Single cell 20 ... Electrolyte membrane 21 ... Anode 22 ... Cathode 23 ... Gas diffusion layer 24 ... Gas diffusion layer 25 ... Gas separator 26, 26A-26D ... Gas separator 30 ... Rib between flow paths 30A ... Flow path Inter-rib 32 ... Groove 34 ... Inlet side closed part 35 ... Outlet side closed part 36 ... Convex part 40-45 ... Hole 47 ... In-cell fuel gas flow path 48 ... In-cell oxidizing gas flow path 48out ... Gas outflow flow path 48in ... Gas inflow channel 49a ... Weir part 49b ... Recess 49c ... Groove opening recess 50 ... Power generation area 60 ... Frame

Claims (5)

A membrane electrode assembly in which electrodes are formed on both membrane surfaces of the electrolyte membrane, a gas diffusion layer provided on at least one electrode surface of the membrane electrode assembly, and a reaction that is subjected to an electrochemical reaction in the gas diffusion layer A fuel cell having a gas flow path for supplying gas,
The gas flow path is
A plurality of gas inflow passages extending from the side of the gas supply manifold for supplying the reaction gas, blocked at the end of the flow passage, and flowing the reaction gas flowing in from the gas supply manifold along the surface of the gas diffusion layer; ,
A gas that extends side by side from the gas discharge manifold side for gas discharge and that is blocked at the end of the flow path and that has passed through the gas diffusion layer from the gas flow path, receives the gas A plurality of gas outflow passages for flowing out to the gas discharge manifold while flowing along the surface of the gas diffusion layer,
The gas inflow channel is
A dam section located on the surface side of the gas diffusion layer to block the gas, and a dam portion for converting the gas flow direction to the side away from the surface of the gas diffusion layer;
Receiving the gas converted into the flow on the side away from the surface of the gas diffusion layer by the dam part, and converting the gas in the flow path over the dam part and flowing toward the surface side of the gas diffusion layer And a fuel cell.   The said dam part inclines the damming surface which a gas collides toward the upstream of the flow of gas to the said upstream so that the angle | corner with the surface of the said gas diffusion layer may become an acute angle. The fuel cell as described.   The in-channel conversion part is formed on the back wall side facing the surface of the gas diffusion layer, and is a recess in the channel that opens toward the dam part. 2. The fuel cell according to 2.   The fuel cell according to any one of claims 1 to 3, wherein the gas inflow channel includes the dam portion and the in-channel conversion unit at a plurality of locations of the gas inflow channel. The gas inflow channel and the gas outflow channel are adjacent to each other as a meandering path meandering in the surface of the gas diffusion layer,
The fuel cell according to any one of claims 1 to 4, wherein the gas inflow passage includes the weir portion and the in-flow passage conversion portion in the meandering path.

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