JP6050158B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell.

  In general, a fuel cell has a structure in which a membrane electrode assembly and a separator are arranged to face each other, and a reaction gas flow path for supplying a reaction gas along the surface of the membrane electrode assembly is formed therebetween. doing. A manifold that allows reaction gas to flow in the stacking direction is formed at the outer edge of the separator, and the reaction gas channel and the manifold are connected by a connection channel.

  Conventionally, Patent Document 1 proposes a configuration in which a plurality of protrusions are provided in an outlet buffer portion that connects a discharge-side manifold and a reactive gas flow channel, that is, an outlet-side connection flow channel. The plurality of projections are for preventing the generated water of the fuel cell from collecting, and according to this configuration, the drainage of the fuel cell can be improved.

JP 2006-278247 A

  When the fuel cell is started in a sub-freezing environment, the generated water of the fuel cell may freeze in the outlet side connection channel. Even in the fuel cell described in Patent Document 1, when the generated water uniformly enters the outlet side connection path, there is a possibility that the entire flow path formed by the protrusions freezes and the outlet side connection path is completely blocked. It was.

  In addition, when a plurality of unit cells including a membrane electrode assembly and a separator are stacked, sealing is performed by a gasket, but since no consideration is given to the surface pressure applied to the seal line by the protruding portion, the sealing is not performed. Sometimes it was incomplete. In addition, cold startability, cost reduction, resource saving, high quality, and easy manufacturing have been desired.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) One embodiment of the present invention is a fuel cell. In this fuel cell, a membrane electrode assembly and a separator are arranged to face each other, and a reaction gas flow path for supplying a reaction gas along the surface of the membrane electrode assembly is formed between them. And a discharge manifold that discharges the reaction gas by flowing the reaction gas in a direction intersecting the surface of the separator; located between the reaction gas flow path and the discharge manifold; And an outlet-side connection flow channel for flowing the reaction gas discharged from the reaction gas flow channel to the discharge manifold. Further, the outlet-side connection flow path includes: a wide flow path having a first flow path width; a narrow flow path having a second flow path width narrower than the first flow path width; And a connecting channel that has a channel width that is equal to or greater than the second channel width and that connects the wide channel and the narrow channel. .

  According to the fuel cell of this embodiment, the generated water is induced by the capillary phenomenon from the wide channel to the connection channel and the narrow channel. For this reason, the connection flow channel and the narrow flow channel become a retention portion of the generated water, and the generated water does not remain in the wide flow channel. Therefore, at the time of starting below the freezing point, at least the wide channel can be prevented from being blocked by freezing. As a result, at the time of starting below freezing, the outlet-side connection channel is not completely blocked, and power generation can be continued.

(2) In the fuel cell of the above aspect, the separator is provided with a plurality of types of convex portions that form the wide channel and the narrow channel; one type of the plurality of types of convex portions is A long convex portion that is continuous along the flow direction of the reaction gas; and another type of the plurality of types of convex portions has a length in the flow direction of the reaction gas that is the long protrusion. It is good also as a structure which is a convex part shorter than a cylindrical member, Comprising: A short convex part which forms the said connection flow path by arranging two or more along the gap in the flow direction of the said reaction gas. According to the fuel cell of this embodiment, it is easy to create a wide flow channel, a narrow flow channel, and a connection flow channel, and the reactive gas easily flows.

(3) In the fuel cell of the above aspect, the long convex portion may have a configuration in which one end in the longitudinal direction exceeds the edge of the discharge manifold. According to the fuel cell of this embodiment, the long convex portion can prevent icing from spreading to the adjacent flow path, so that the blockage due to freezing can be further avoided.

(4) In the fuel cell of the above aspect, the long convex portion may have a configuration in which the other end in the longitudinal direction reaches a region occupied by the membrane electrode assembly. According to this type of fuel cell, it is possible to further avoid blockage due to freezing.

(5) The fuel cell according to the above aspect includes a seal member that forms a seal line for suppressing leakage of the reaction gas or the cooling medium by being in contact with the separator, from the thickness direction of the separator. In the plan view, the connection channel may be arranged so as not to overlap the seal line. According to the fuel cell of this embodiment, it is possible to reliably ensure the seal surface pressure at the time of stacking.

(6) In the fuel cell of the above aspect, when the length in the flow direction of the reaction gas is a vertical width and the length in a direction perpendicular to the flow direction is a horizontal width, The ratio of the vertical width to the width may be in the range of 1.05 to 5.0. According to the fuel cell of this aspect, the size of the short convex portion can be made appropriate, and further, it is easier to secure the seal surface pressure by the seal line.

  According to another aspect of the invention, another fuel cell is provided. In this fuel cell, a membrane electrode assembly and a separator are arranged to face each other, and a reaction gas flow path for supplying a reaction gas along the surface of the membrane electrode assembly is formed between them. And a discharge manifold that discharges the reaction gas by flowing the reaction gas in a direction intersecting the surface of the separator; located between the reaction gas flow path and the discharge manifold; An outlet-side connection channel for flowing the reaction gas discharged from the reaction gas channel to the discharge manifold; and the outlet-side connection channel; a wide channel having a first channel width; And a narrow channel having a second channel width that is narrower than the first channel width. According to the fuel cell of this configuration, the narrow flow path is narrower than the wide flow path, so that it is easy to block, but the wide flow path is difficult to block. For this reason, at the time of starting below freezing point, there is little possibility that the outlet side connecting flow path is completely blocked.

  The present invention can be realized in various forms other than the fuel cell of the above-described form. For example, it is realizable with forms, such as a fuel cell system provided with the fuel cell of the above-mentioned form.

It is explanatory drawing which decomposes | disassembles and shows the single cell inside a fuel cell. It is an AA arrow end view in the time of the assembly state of the single cell shown in FIG. It is explanatory drawing which shows the planar view from the lamination direction of the periphery of the through-hole which comprises the manifold for cathode offgas discharge | emission. It is explanatory drawing which shows the mode of induction | guidance | derivation of produced water in detail. It is explanatory drawing which shows the periphery of the exit side connection flow path formed in the 2nd separator in 2nd Embodiment. It is explanatory drawing which shows the periphery of the exit side connection flow path formed in the 2nd separator in 3rd Embodiment. It is explanatory drawing which shows the relationship between a pitch and the height of a convex-shaped part.

Next, an embodiment of the present invention will be described.
A. First embodiment:
A-1. Overall configuration of the fuel cell:
FIG. 1 is an exploded view showing a single cell 10 inside a fuel cell. This fuel cell is a polymer electrolyte fuel cell and has a stack structure in which a plurality of single cells 10 shown in FIG. 1 are stacked and connected in series.

  As shown in FIG. 1, the single cell 10 includes a power generator 100, a first separator 300, and a second separator 400. The power generation body 100 includes a membrane-electrode assembly (MEA) 110 and a pair of gas diffusion layers 120 and 130 disposed so as to sandwich both surfaces of the MEA 110, thereby forming a power generation region.

  The MEA 110 includes an electrolyte membrane 112 and a pair of catalyst electrode layers 114 and 116 disposed so as to sandwich both surfaces of the electrolyte membrane 112. The electrolyte membrane 112 is a polymer electrolyte membrane formed of a fluorine-based sulfonic acid polymer as a solid polymer material, and has good proton conductivity in a wet state. As the electrolyte membrane 112, in addition to the fluorine-based sulfonic acid film, a fluorine-based phosphonic acid film, a fluorine-based carboxylic acid film, or the like may be used. The catalyst electrode layers 114 and 116 as anodes and cathodes include, for example, a catalyst-supporting carrier (for example, carbon particles) supporting a catalyst metal (for example, platinum) that progresses an electrochemical reaction, and a polymer electrolyte having proton conductivity. (For example, fluorine resin). As the catalyst-supporting carrier, in addition to carbon particles, for example, carbon materials such as carbon black, carbon nanotubes, carbon nanofibers, carbon compounds represented by silicon carbide, and the like may be used. Moreover, as a catalyst metal, you may use platinum alloy, palladium, rhodium etc. other than platinum, for example.

  The pair of gas diffusion layers 120 and 130 is a layer for diffusing a reaction gas used for the electrode reaction along the surface direction of the electrolyte membrane 112, and is composed of a porous gas diffusion layer base material. As the gas diffusion layer substrate, for example, a carbon porous body such as carbon paper or carbon cloth, or a metal porous body such as a metal mesh or a foam metal can be used.

  The first separator 300 and the second separator 400 are disposed so as to sandwich the power generation body 100 and the gas closing / electrical insulating materials 210 and 220 (FIG. 2) from both sides.

  FIG. 2 is an end view taken along line AA when the unit cell 10 shown in FIG. 1 is assembled. The gas closing / electrical insulating material 210, 220 is located between the pair of separators 300, 400, particularly on the outer periphery of the power generating body 100 between the pair of separators 300, 400, so that the separators 300, 400 are short-circuited. In addition, the reaction gas and the cooling medium passing through the inside of the single cell 10 are prevented from leaking outside. The gas closing / electrical insulating materials 210 and 220 are made of polypropylene. The gas closing / electrical insulating materials 210 and 220 may be formed using other resins such as a phenol resin and an epoxy resin.

  Returning to FIG. 1, the first separator 300 is disposed on the anode (gas diffusion layer 120) side, which is one side of the MEA 110, and the second separator 400 is on the cathode (gas diffusion layer 130) side, which is the other side. Is arranged.

  The first and second separators 300 and 400 are made of a member having gas barrier properties and electronic conductivity, and the outer shape is rectangular. The first and second separators 300 and 400 are formed of, for example, a carbon member such as dense carbon that is made gas impermeable by compressing carbon particles, or a metal member such as press-molded stainless steel.

  The first and second separators 300 and 400 are formed with through holes 421, 422, 431, 432, 441, and 442 that constitute a part of the manifold, respectively. Specifically, the through hole 421 constitutes a part of the manifold M1 for circulating the anode supply gas (hydrogen gas) supplied from the outside, and the through hole 422 is a part of the manifold M2 for circulating the anode off gas. Parts. The through hole 431 constitutes a part of the manifold M3 for circulating the cathode supply gas (air) supplied from the outside, and the through hole 432 constitutes a part of the manifold M4 for circulating the cathode off gas. . The through hole 441 constitutes a part of the manifold M5 for circulating the cooling medium supplied from the outside, and the through hole 442 constitutes a part of the manifold M6 for circulating the discharged cooling medium.

  The gas closing / electrical insulating materials 210 and 220 (FIG. 2) disposed on the outer periphery of the power generation body 100 described above have six through holes corresponding to the through holes 421, 422, 431, 432, 441, and 442, respectively. Holes (FIG. 2: 232) are formed, and the through holes 421 to 442 and the six through holes are arranged in the stacking direction of the first separator 300, the power generation body 100, and the second separator 400 (hereinafter simply referred to as “separate holes”). (Referred to as the “stacking direction”) For communicating with the Y, the air supply, the hydrogen gas supply, the hydrogen gas discharge, the air discharge, the cooling medium supply, and the cooling medium discharge in a shape extending in the stacking direction Y The manifolds M1 to M6 are configured. The stacking direction Y is also the thickness direction of each separator 300, 400. In the present embodiment, the flow direction of the fluid in each of the manifolds M1 to M6 is the direction along the stacking direction Y, but it is not always necessary to completely match the stacking direction, and the direction intersecting the surfaces of the separators 300 and 400 Any direction may be used.

  As shown in FIG. 1, a groove channel 450 ca (only a part is shown on the back side in the drawing) is formed on the surface of the second separator 400 facing the power generation body 100. The groove channel 450ca has a meandering shape that extends in a direction along one side of the second separator 400 (X direction in the drawing) and turns back on the surface facing the power generation body 100. The groove channel 450ca communicates with the manifolds M3 and M4, supplies the air flowing through the manifold M3 to the gas diffusion layer 130 serving as the cathode of the power generation body 100, and distributes the cathode off-gas that has circulated through the power generation body 100 to the manifold M4. The groove channel 450ca and the manifold M3 communicate with each other through an inlet-side connection channel 460 formed in the second separator 400. Further, the groove channel 450ca and the manifold M4 are communicated with each other by an outlet side connection channel 470 formed in the second separator 400. A groove channel (not shown) is formed on the surface of the second separator 400 opposite to the side where the power generator 100 is located. This groove flow path communicates with the manifolds M5 and M6, and the cooling medium flows therethrough.

  A groove flow path 450an (only a part is shown on the back side in the figure) is formed on the surface of the first separator 300 facing the power generation body 100. The groove channel 450an has a meandering shape that extends in a direction (X direction in the drawing) along one side of the first separator 300 on the surface facing the power generation body 100 and turns back. The groove channel 450an communicates with the manifold M1, supplies the hydrogen gas flowing through the manifold M1 to the gas diffusion layer 120 serving as the cathode of the power generation body 100, and distributes the anode off-gas flowing through the power generation body 100 to the manifold M2. The groove channel 450an and the manifold M1 communicate with each other through an inlet-side connection channel (not shown) formed in the first separator 300. The groove channel 450an and the manifold M2 communicate with each other through an outlet-side connection channel (not shown) formed in the first separator 300. A groove channel 490 (only a part of which is shown) is formed on the surface of the first separator 300 opposite to the side where the power generation body 100 is located. The groove channel 490 communicates with the manifolds M5 and M6, and the cooling medium flows therethrough.

  Furthermore, the outer peripheral edge of the first separator 300, the through holes 421 and 422 for hydrogen gas, on the surface of the first separator 300 opposite to the side where the power generator 100 is located, Seal lines SL are formed to surround the air through holes 431 and 432, respectively. This seal line SL is constituted by a gasket 510 shown in FIG. The gasket 510 is formed by injection molding and has a convex cross section. When a plurality of single cells 10 are stacked, the single cell 10 is in close contact with the surface of another adjacent single cell 10 to form a seal line SL (FIG. 1). The seal line SL is for suppressing leakage of hydrogen gas, air, and a cooling medium. The cooling medium flows between the first separator 300 and the second separator 400 by the seal line SL. The gasket 510 that forms the seal line SL corresponds to the “seal member” described in the “Summary of Invention” section.

  In the present embodiment, the X direction along one side of the first and second separators 300 and 400 described above is perpendicular to the stacking direction Y. The Z direction in the drawing perpendicular to the X direction and the stacking direction Y is a direction along the other side of the first and second separators 300 and 400. The fuel cell is installed so that the Z direction is vertically downward.

A-2. Configuration of outlet side connection flow path:
Next, the outlet side connection channel 470 formed in the second separator 400 will be described in detail. As described above, the outlet-side connection flow path 470 connects the groove flow path 450ca and the manifold M4, and is formed by a plurality of convex portions as shown in the blow-out view of FIG. . There are two types of convex portions, and one of the two types is the long convex portion 480L, and the other is the short convex portion 480S. The length of the long convex portion 480L in the longitudinal direction is longer than the length of the short convex portion 480S in the longitudinal direction. The long convex portions 480L and the short convex portions 480S are arranged so that their longitudinal directions are along the aforementioned X direction, which is the cathode off-gas flow direction from the groove flow channel 450ca. Three short convex portions 480S are arranged in the direction X with a gap (see also FIG. 2). Each flow path is formed by alternately arranging one long convex portion 480L and three short convex portions 480S in the Z direction. In the present embodiment, the end of the long convex portion 480L on the groove channel 450ca side is not connected to the groove channel 450ca, and the end of the long convex portion 480L on the manifold M4 side Is configured so as not to reach the edge of the manifold M4.

  In the present embodiment, the three short convex portions 480S constitute a row along the flow direction of the reaction gas, but instead, in other plural such as two, four, five, A line along the flow direction of the reaction gas may be formed. According to this structure, the clearance gap between the adjacent short convex-shaped parts as a connection flow path can be made into numbers other than two.

  A channel 470W formed by the arrangement of the three short convex portions 480S and one side of the two adjacent long convex portions 480L has a first flow channel width a. On the other hand, the flow path 470N formed by the arrangement of the three short convex portions 480S and the other side of the two adjacent long convex portions 480L is a second narrower than the first flow passage width a. It has a channel width b. Hereinafter, the flow path 470W is referred to as a wide flow path 470W, and the flow path 470N is referred to as a narrow flow path 470N.

  Furthermore, in the present embodiment, the width c (referred to as “gap width”) c between the adjacent short convex portions 480S and 480S is shorter than the first flow path width a, and the second It is longer than the channel width b. That is, the first flow path width a> the gap width c> the second flow path width b. Alternatively, the gap width c may be the same as the first channel width a or the second channel width b. That is, the gap width c may be any length as long as it is not more than the first channel width a and not less than the second channel width b. The gap 482 corresponds to the “connection channel” described in the “Summary of the Invention” column.

  FIG. 3 is an explanatory view showing a plan view from the stacking direction Y around the through hole 432 constituting the manifold M4 for discharging the cathode off gas. In FIG. 3, the first separator 300 is indicated by a solid line, and the second separator 400 is indicated by a broken line. As shown in the drawing, in plan view from the stacking direction Y, the position of the seal line SL and the short convex portions 480S and 480S is such that the seal line SL does not overlap the gap 482 between the short convex portions 480S and 480S. Is stipulated. Here, overlapping means that at least a part of the gap 482 overlaps at least a part of the seal line SL. In the present embodiment, the gap 482 is a plan view from the stacking direction Y with respect to the seal line SL. However, it is stipulated that not only the whole but also the part does not overlap.

  Furthermore, in the present embodiment, the size of the short convex portion 480S is defined as follows. As shown in the blow-out diagram of FIG. 1, the length in the flow direction X of the reaction gas with respect to the short convex portion 480 </ b> S is the vertical width L <b> 1, and the direction perpendicular to the flow direction X in plan view from the stacking direction Y When the length of Z is the horizontal width L2, the ratio (L1 / L2) of the vertical width L1 to the horizontal width L2 is 2.5. This ratio may be varied within the range of 1.05 to 5.0. The lateral width L2 is 0.2 to 2 [mm] in the present embodiment. With such a configuration, it becomes easy to overlap the seal line SL on the portion of the short convex portion 480S.

  Note that the inlet-side connection flow path 460 formed in the second separator 400 also has an arrangement of one long convex portion and three short convex portions, similar to the outlet-side connection flow path 470 described above. However, each flow path has a structure formed by being alternately arranged. Also, the inlet-side connection channel and the outlet-side connection channel formed in the first separator 300 also have one long convex portion and three short convex portions, like the outlet-side connection channel 470 described above. The arrangement of the shape portions is alternately arranged, so that each flow path is shaped.

A-3. effect:
According to the fuel cell of the first embodiment configured as described above, the gap between the wide flow path 470W and the narrow flow path 470N in the outlet-side connection flow path 470 is between the adjacent short convex portions 480S and 480S. The gap width c is shorter than the flow path width a of the wide flow path 470W, and is longer than the flow path width b of the narrow flow path 470N. For this reason, the generated water is induced by the capillary phenomenon from the wide channel 470W to the gap 482 and the narrow channel 470N.

  FIG. 4 is an explanatory diagram showing in detail how the generated water is guided. The generated water W is generated in the power generation body 100 (and is discharged from the groove channel 450ca. As shown in the drawing, the generated water W flowing from the groove channel 450ca once enters the wide channel 470W. However, due to the capillary force and gravity due to the capillary phenomenon, it flows into the narrow flow path 470N through the gap 482. The narrow flow path 470N is narrower than the wide flow path 470W and is likely to be blocked by the above flow. When the amount of water is large or the flow rate is low, the generated water W stays in the narrow flow path 470N or further in the portion including the gap 482. Therefore, the generated water W stays in the wide flow path 470W. In other words, the gap 482 and the narrow channel 470N serve as a retained portion of the produced water, and the produced water does not remain in the wide channel 470W.

  At the time of starting below the freezing point, the generated water W mainly stays in the narrow channel 470N because the generated water is small and the flow velocity is low. Here, when some supercooled product water freezes up for some reason and becomes frozen nuclei, the nuclei grow and freeze at the site of the narrow channel 470N, so even if icing occurs, The wide flow path 470W is not blocked. Therefore, at the time of starting below the freezing point, the wide flow path 470W is free from blockage due to freezing. As a result, according to the fuel cell of the first embodiment, the power generation can be continued without the outlet-side connecting flow path 470 being completely blocked at the time of starting below freezing.

  Further, according to the first embodiment, as described with reference to FIG. 3, the gap 482 between the adjacent short convex portions 480S and 480S in the plan view from the stacking direction Y is the first separator 300. The seal line SL is positioned so as not to overlap with the seal line SL provided on the surface, and the seal line SL is located at a site where the long convex portion 480L and the short convex portion 480S exist, so that the seal surface pressure during the stacking is ensured. Can be secured. Therefore, the fluid sealing performance in the fuel cell can be improved.

B. Second embodiment:
FIG. 5 is an explanatory view showing the periphery of the outlet-side connection flow path formed in the second separator 1400 in the second embodiment. This figure is a view of the periphery of the outlet-side connection flow channel as viewed from the stacking direction. The fuel cell in the second embodiment is different from the fuel cell in the first embodiment in that the length of the long convex portion 1480L in the longitudinal direction is longer. Since the other configurations of the fuel cell including the short convex portion 480S are the same as the configuration of the fuel cell in the first embodiment, the same components as those in the first embodiment are denoted by the same reference numerals. The description is omitted.

  As shown in the drawing, one end ed1 in the longitudinal direction of the long convex portion 1480L reaches the power generation region 100X, and the other end ed2 in the longitudinal direction of the long convex portion 1480L extends to the edge M4ed of the manifold M4. It has a configuration that exceeds. The power generation region 100X is a region in contact with the separator 400 of the power generation body 100, that is, a region occupied by the MEA in a plan view from the stacking direction.

  Note that the outlet-side connection flow path formed in the first separator 300 also has a length in the longitudinal direction of the long convex portion 1480L, similar to the above-described outlet-side connection flow path formed in the second separator 400. Is longer than that of the first embodiment.

  According to the fuel cell of the second embodiment configured as described above, the long convex portion 1480L becomes so long that it exceeds the edge M4ed of the manifold M4, so that icing spreads to the adjacent flow path. Can be prevented. Further, the long convex portion 1480L can be prevented from spreading to the adjacent flow path by being long enough to reach the power generation region 100X. From these things, the blockage by freezing can be avoided more. Therefore, at the time of starting below the freezing point, the outlet-side connecting flow path is more reliably prevented from being completely blocked, and power generation can be continued.

  As a modification of the second embodiment, one end ed1 in the longitudinal direction of the long convex portion 1480L may not reach the power generation region 100X, or the longitudinal direction of the long convex portion 1480L. The other end ed2 may be configured not to exceed the edge M4ed of the manifold M4.

C. Third embodiment:
FIG. 6 is an explanatory view showing the periphery of the outlet-side connection flow path formed in the second separator in the third embodiment. In each of the first and second embodiments described above, the wide channel, the narrow channel, and the connection channel are formed by the long convex portion and the short convex portion. In the third embodiment, the wide channel 2470W, the narrow channel 2470N, and the connecting channel 2482 are formed only by the short convex portion 2480S having the same size. The short convex portion 2480S is the same as the short convex portion 480S of the first embodiment. Similarly to the first embodiment, the width c of the connection channel 2482 is shorter than the first channel width a and longer than the second channel width b. The other configuration of the fuel cell is the same as that of the first embodiment.

  Even with the fuel cell of the third embodiment configured as described above, as in the first embodiment, the outlet-side connection flow path is prevented from being completely blocked during sub-freezing start and power generation is continued. Can be made.

  In addition, each said embodiment and its modification prescribe | regulate the width | variety of the flow path formed with a convex-shaped part, and the distance (henceforth a "pitch") between convex parts and convex-shaped. The relationship with the height of the section has not been mentioned in particular, but this relationship is as follows. FIG. 7 is an explanatory diagram showing the relationship between the pitch and the height of the convex portion in the first embodiment. Fig.7 (a) is a top view and is the same as the blowing figure of FIG. FIG.7 (b) is a BB arrow directional view of Fig.7 (a). As shown in FIG. 7B, in the outlet side connection channel 470, the distance between the vertex of the long convex portion 480L and the vertex of the short convex portion 480S sandwiching the wide channel 470W is defined as the first pitch P1. When the distance between the apex of the short convex portion 480S and the apex of the long convex portion 480L across the narrow channel 470N is the second pitch P2, P1 and P2 are both the height h of the convex portion. Is in the range of 0.2 to 2.0 times the length. The height h of the convex portion is the apex and the other side on one side of the corrugated sheets forming the long convex portion 480L and the short convex portion 480S (the positive side and the negative side in the Y direction in FIG. 1). It is the length in the Y direction between the vertices. “0.2 to 2.0 times” is a range that satisfies the condition of being larger than 0.2 times and smaller than 2.0 times. In this way, the surface pressure applied to the seal can be maintained by limiting the pitches P1 and P2 to the range defined by the height h.

  The relationship between the pitches P1, P2 between the vertices of the convex portions and the height of the convex portions has the same relationship not only in the first embodiment, but also in the second embodiment and their modifications. ing. Furthermore, this relationship, that is, when the pitch is P and the height is h, is 0.2h <P <2.0h. The present invention can also be applied to a fuel cell having a constant outlet-side connection flow path.

D. Variations:
・ Modification 1:
In each of the above-described embodiments and variations thereof, the cathode-side groove flow channel 450ca and the anode-side groove flow channel 450an have a meandering shape, but may be replaced with other shapes such as a straight shape.

・ Modification 2:
In each of the embodiments and variations thereof, the inlet-side connection flow path and the outlet-side connection flow path formed in the first separator, and the inlet-side connection flow path and the outlet-side connection flow path formed in the second separator. However, each flow path is formed by alternately arranging one long convex portion and an arrangement of three short convex portions, but instead, Only both outlet side connection flow paths of the first and second separators may have the above structure. Further, only the outlet side connection flow path formed in the first separator may have the above structure, or only the outlet side connection flow path formed in the second separator may have the above structure. Since the outlet-side connecting flow path formed in the second separator is on the cathode side of the MEA, the generated water is larger than that on the anode side. Therefore, the outlet-side connecting flow path formed in the second separator has the above structure. Therefore, the startability at the time of starting below freezing can be further improved.

-Modification 3:
In each of the above-described embodiments and variations thereof, the polymer electrolyte fuel cell is used as the fuel cell, but various fuel cells such as a phosphoric acid fuel cell, a molten carbonate fuel cell, and a solid oxide fuel cell are used. The present invention may be applied.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Moreover, elements other than the elements described in the independent claims among the constituent elements in the above-described embodiments and modifications are additional elements and can be omitted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Single cell 100 ... Electric power generation body 110 ... Membrane electrode assembly (MEA)
DESCRIPTION OF SYMBOLS 112 ... Electrolyte membrane 114 ... Catalyst electrode layer 120 ... Gas diffusion layer 130 ... Gas diffusion layer 210, 220 ... Electrical insulating material 300 ... 1st separator 400 ... 2nd separator 421,422 ... Through-hole 431,432 ... Through-hole 441, 442 ... Through hole 450ca ... Groove channel 450an ... Groove channel 460 ... Inlet side connection channel 470 ... Outlet side connection channel 470N ... Narrow channel 470W ... Wide channel 480L ... Long convex part 480S ... Short convex part 482 ... Gap 490 ... Groove flow path 510 ... Gasket 1400 ... Second separator 1470W ... Wide flow path 1480L ... Long convex part 2470 ... Outlet side connection flow path 2470N ... Narrow flow path 2470W ... Wide flow Road 2480S ... Short convex part

Claims (6)

A fuel cell in which a membrane electrode assembly and a separator are arranged to face each other, and a reaction gas flow path for supplying a reaction gas along the surface of the membrane electrode assembly is formed between the two,
In the separator,
A discharge manifold for discharging the reaction gas by flowing the reaction gas in a direction intersecting the surface of the separator;
An outlet-side connection channel that is located between the reaction gas channel and the discharge manifold, and that allows the reaction gas discharged from the reaction gas channel to flow to the discharge manifold;
Is provided,
The outlet-side connection flow path is
A wide channel having a first channel width;
A narrow channel having a second channel width narrower than the first channel width;
A connecting channel that has a channel width that is less than or equal to the first channel width and that is greater than or equal to the second channel width and that connects the wide channel and the narrow channel; ,
Including a fuel cell. The fuel cell according to claim 1,
The separator is provided with a plurality of types of convex portions that form the wide channel and the narrow channel,
One type of the plurality of types of convex portions is a long convex portion that is continuous along the flow direction of the reaction gas,
Another type of the plurality kinds of convex portions has a length in the flow direction of the reaction gas is a said elongate protruding portion by remote short convex portions, the flow direction of the reaction gas A fuel cell, which is a short convex portion that forms the connection flow path by arranging a plurality of lines along a gap. The fuel cell stack according to 請 Motomeko 2,
The long convex portion is a fuel cell having a configuration in which one end in a longitudinal direction exceeds an edge of the discharge manifold. The fuel cell according to claim 3, wherein
The long convex portion is a fuel cell having a configuration in which the other end in the longitudinal direction reaches a region occupied by the membrane electrode assembly. A fuel cell according to any one of claims 1 to 4, wherein
A seal member that forms a seal line for suppressing leakage of the reaction gas or the cooling medium by being in contact with the separator;
The fuel cell, wherein the connection channel is disposed so as not to overlap the seal line in a plan view from the thickness direction of the separator. The fuel cell according to claim 2 , wherein
When the length in the flow direction of the reaction gas is defined as the vertical width and the length in the direction perpendicular to the flow direction is defined as the horizontal width, the ratio of the vertical width to the horizontal width is 1.05. A fuel cell in the range up to 5.0.

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