JP2015002061A - Fuel cell stack - Google Patents

Abstract

[PROBLEMS] To easily discharge generated water with a simple and compact configuration, and to secure desired power generation performance.
A fuel cell constituting a fuel cell stack includes a cathode separator. The cathode-side separator 14 includes an oxidant gas passage 30 and an inlet buffer portion 32a and an outlet having a plurality of connecting passage grooves 36a and 38a connected to the inlet side and the outlet side of the oxidant gas passage 30, respectively. And a buffer unit 32b. The oxidant gas flow path 30, the inlet buffer part 32a, and the outlet buffer part 32b are provided with a depth variation part 40 in which the flow path depth partially decreases in the oxidant gas flow direction.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell stack having a fuel cell in which an electrolyte membrane / electrode structure provided with electrodes on both sides of an electrolyte membrane and a separator are stacked, and a plurality of the fuel cells are stacked.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure in which an anode electrode is provided on one side of an electrolyte membrane made of a polymer ion exchange membrane and a cathode electrode is provided on the other side of the electrolyte membrane ( MEA). The electrolyte membrane / electrode structure is sandwiched between a pair of separators to constitute a unit cell (power generation cell). This type of fuel cell is normally used as an in-vehicle fuel cell stack by stacking a predetermined number of unit cells.

  In the above fuel cell, a fuel gas channel (hereinafter also referred to as a reaction gas channel) for flowing fuel gas is provided in the surface of one separator so as to face the anode electrode. In addition, an oxidant gas flow path (hereinafter also referred to as a reaction gas flow path) for flowing an oxidant gas is provided in the surface of the other separator so as to face the cathode electrode. Furthermore, between each separator which comprises each fuel cell and adjoins mutually, the cooling medium flow path for flowing a cooling medium in the electrode range is formed along the separator surface.

  Meanwhile, in the oxidant gas flow path, the generated water generated by the power generation reaction tends to stay, whereas in the fuel gas flow path, the generated water obtained by reverse diffusion of the MEA may stay. Furthermore, in the surface of the separator, the introduced water is condensed and condensed water is likely to be generated. For this reason, the inside of a flow path is obstruct | occluded by a stagnant water or dew condensation water, the supply shortage of a reactive gas is caused, and the membrane degradation of MEA and the fall of power generation performance may generate | occur | produce.

  Thus, for example, a fuel cell disclosed in Patent Document 1 is known. This fuel cell includes a cell in which an anode electrode is formed on one surface of an electrolyte body and a cathode electrode is formed on the other surface, a fuel plate, and an oxidizer plate. The fuel plate has a plurality of fuel chambers through which fuel gas flows, a fuel introduction path for supplying the fuel gas to the fuel chamber, and a fuel discharge path for discharging fuel exhaust gas discharged from the fuel chamber. Yes. The oxidant plate is provided independently for each of the plurality of oxidant chambers through which the oxidant gas flows, the oxidant introduction path for supplying the oxidant gas to the oxidant chamber, and the plurality of oxidant chambers. And an oxidant discharge path for discharging the oxidant exhaust gas discharged from the oxidant chamber.

  In this fuel cell, a cell unit is constituted by sandwiching the cell between a fuel plate and an oxidant plate so that a fuel chamber faces the anode side of the cell and an oxidant chamber faces the cathode side. The oxidant discharge path includes a first opening communicating with the oxidant chamber and a second opening communicating with the outside air. At that time, the cross-sectional area is formed so as to gradually decrease from the first opening toward the second opening, and the main planar shapes of the ribs are all the same.

  Therefore, in the oxidant discharge path, the gas pressure increases from the first opening toward the second opening, and the flow rate of the oxidant gas increases, so that moisture is discharged from the oxidant discharge path vigorously. It is said.

Japanese Patent No. 3679789

  However, in the fuel cell described above, an oxidant discharge path that is a flow passage is provided outside the oxidant chamber that is a power generation unit. For this reason, it is necessary to provide a non-power generation region in addition to the power generation unit, and there is a problem that the power generation efficiency of the entire fuel cell is reduced and the size is increased.

  The present invention solves this type of problem, and provides a fuel cell stack that can discharge generated water satisfactorily with a simple and compact configuration and can ensure desired power generation performance. For the purpose.

  The fuel cell stack according to the present invention has a fuel cell in which an electrolyte membrane / electrode structure provided with electrodes on both sides of an electrolyte membrane and a separator are laminated, and a plurality of the fuel cells are laminated. The fuel cell stack is formed with a reaction gas inlet communication hole and a reaction gas outlet communication hole through which the reaction gas flows in the stacking direction.

  In this fuel cell stack, the separator is provided with a reaction gas flow path that communicates with the reaction gas inlet communication hole and the reaction gas outlet communication hole and distributes the reaction gas along the separator surface. The separator is provided with a buffer portion having a plurality of connection channels connected to the inlet side and the outlet side of the reaction gas channel. At least the reaction gas flow path or the connection flow path of the buffer part is provided with a depth varying portion in which the flow path depth partially decreases in the reaction gas flow direction.

  Further, in this fuel cell stack, a plurality of depths at which the flow path depth is partially reduced by discontinuously disposing a plurality of convex members in at least the reaction gas flow path or the connection flow path. It is preferable that a variable part is provided.

  Furthermore, in this fuel cell stack, it is preferable that the convex member includes at least a plurality of types of the convex members having different height dimensions or shapes.

  According to the present invention, the depth variation portion is provided in the reaction gas flow path or the connection flow path of the buffer portion, and the pressure loss (pressure loss) increase portion is reduced in the flow path by decreasing the flow path depth. Partially provided. For this reason, in the flow path, the staying generated water and dew condensation water are discharged well by the increase and decrease of the pressure loss, and the drainage is easily improved. Therefore, the generated water can be discharged satisfactorily with a simple and compact configuration, and desired power generation performance can be ensured.

1 is an exploded perspective view of a main part of a fuel cell constituting a fuel cell stack according to a first embodiment of the present invention. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is front explanatory drawing of the cathode side separator which comprises the said fuel cell. It is a perspective explanatory view of the depth variation part provided in the cathode side separator. FIG. 5 is a cross-sectional view of the depth varying portion taken along line VV in FIG. 4. FIG. 6 is a cross-sectional view of the depth varying portion taken along line VI-VI in FIG. 4. It is the VII-VII sectional view taken on the line of FIG. 4 of the said depth fluctuation | variation part. It is front explanatory drawing of the anode side separator which comprises the said fuel cell. It is a principal part disassembled perspective explanatory drawing of the fuel cell which comprises the fuel cell stack which concerns on the 2nd Embodiment of this invention.

  As shown in FIGS. 1 and 2, the fuel cell stack 10 according to the first embodiment of the present invention includes a plurality of fuel cells 11 in the standing direction (the electrode surface is parallel to the vertical direction) in the arrow A direction. Laminated. The fuel cell 11 may be stacked in the arrow C direction in a horizontal posture (the electrode surface is parallel to the horizontal direction).

  The fuel cell 11 includes an electrolyte membrane / electrode structure 12, and a cathode side separator 14 and an anode side separator 16 that sandwich the electrolyte membrane / electrode structure 12. The cathode side separator 14 and the anode side separator 16 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a thin plate-like metal separator whose surface is subjected to anticorrosion treatment.

  The metal separator has a rectangular planar shape, and is formed into a concavo-convex shape by pressing into a wave shape. The cathode side separator 14 and the anode side separator 16 may be constituted by, for example, a carbon separator instead of the metal separator.

  The cathode-side separator 14 and the anode-side separator 16 have a horizontally long shape, and the short sides are directed in the direction of gravity (arrow C direction) and the long sides are directed in the horizontal direction (arrow B direction) (horizontal stacking). Composed. In addition, you may comprise so that a short side may face a horizontal direction and a long side may go to a gravitational direction.

  The oxidant gas inlet communication hole (reactive gas inlet communication hole) 18a and the fuel gas outlet communication hole (reaction) communicate with each other in the arrow A direction at one end edge of the long side direction (arrow B direction) of the fuel cell 11. Gas outlet communication hole) 20b. The oxidant gas inlet communication hole 18a supplies an oxidant gas, for example, an oxygen-containing gas. The fuel gas outlet communication hole 20b discharges fuel gas, for example, hydrogen-containing gas. The oxidant gas inlet communication hole 18a and the fuel gas outlet communication hole 20b have a substantially rectangular shape (may be substantially triangular), and the oxidant gas inlet communication hole 18a is larger than the fuel gas outlet communication hole 20b. The opening area is set.

  A fuel gas inlet communication hole (reactive gas inlet communication hole) 20a for supplying fuel gas, which communicates with each other in the direction of arrow A, and an oxidant gas are communicated with the other end edge in the long side direction of the fuel cell 11. An oxidant gas outlet communication hole (reaction gas outlet communication hole) 18b for discharging is provided. The oxidant gas outlet communication hole 18b and the fuel gas inlet communication hole 20a have a substantially rectangular shape, and the oxidant gas outlet communication hole 18b is set to have a larger opening area than the fuel gas inlet communication hole 20a.

  Two cooling medium inlet communication holes 22 a for communicating with each other in the direction of arrow A and for supplying a cooling medium are provided at one end of both ends in the short side direction (arrow C direction) of the fuel cell 11. Two cooling medium outlet communication holes 22b for discharging the cooling medium are provided on the other end of both ends in the short side direction of the fuel cell 11.

  The opening shape of the cooling medium inlet communication hole 22a is set to a substantially rectangular shape that is long along the arrow B direction. The opening shape of the cooling medium outlet communication hole 22b is set to be a substantially rectangular shape that is long along the arrow B direction.

  As shown in FIG. 2, the electrolyte membrane / electrode structure 12 includes, for example, a fluorine-based or hydrocarbon-based solid polymer electrolyte membrane 24 and a cathode electrode 26 and an anode electrode 28 that sandwich the solid polymer electrolyte membrane 24. With.

  The cathode electrode 26 and the anode electrode 28 are formed by uniformly applying a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) to be formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 24.

  As shown in FIG. 3, on the surface 14a of the cathode-side separator 14 facing the electrolyte membrane / electrode structure 12, an oxidant gas flow path that connects an oxidant gas inlet communication hole 18a and an oxidant gas outlet communication hole 18b. 30 is formed. The oxidant gas flow path 30 extends in the horizontal direction (arrow B direction), and has a plurality of linear (or wave-shaped) flow path grooves 30a through which the oxidant gas flows in the long side direction along the separator surface. Have.

  The flow channel 30a is formed between the convex portions 30b extending in parallel with each other in the arrow B direction. The convex portion 30b is provided so as to protrude toward the surface 14a by forming the cathode side separator 14 into a wave shape in the thickness direction.

  An inlet buffer portion 32 a is provided in the vicinity of the inlet of the oxidant gas flow path 30, and an outlet buffer portion 32 b is provided in the vicinity of the outlet of the oxidant gas flow path 30. The inlet buffer portion 32a has a substantially triangular shape along the shape of the oxidant gas inlet communication hole 18a and the fuel gas outlet communication hole 20b, and a plurality of the protrusions projecting toward the surface 14a in the vicinity of the oxidant gas inlet communication hole 18a. The emboss 34a is provided.

  The inlet buffer portion 32a has a plurality of connecting flow channel grooves 36a that allow the inlet of the oxidant gas flow channel 30 to communicate with the oxidant gas inlet communication hole 18a. The connecting flow channel groove 36a is set so as to become longer in order from the upper side to the lower side of the cathode separator 14. The connection channel groove 36a is formed between the connection convex portions 36b that are inclined downward in the direction of the arrow B and extend substantially parallel to each other. The connecting convex portion 36b is provided so as to protrude toward the surface 14a by forming the cathode side separator 14 into a wave shape in the thickness direction.

  The outlet buffer portion 32b has a substantially triangular shape along the shapes of the oxidant gas outlet communication hole 18b and the fuel gas inlet communication hole 20a, and a plurality of the outlet buffer parts 32b project toward the surface 14a in the vicinity of the oxidant gas outlet communication hole 18b. The emboss 34b is provided.

  The outlet buffer section 32b has a plurality of connecting flow channel grooves 38a that allow the outlet of the oxidant gas flow channel 30 and the oxidant gas outlet communication hole 18b to communicate with each other. The connection channel groove 38a is set to be shorter in order from the upper side to the lower side of the cathode separator 14. The connection flow path groove 38a is formed between the connection convex portions 38b inclined downward in the direction of the arrow B and extending substantially parallel to each other. The connecting convex portion 38b is provided so as to protrude toward the surface 14a by forming the cathode side separator 14 into a wave shape in the thickness direction.

  In the first embodiment, at least one of the oxidant gas flow channel 30, the inlet buffer unit 32 a and the outlet buffer unit 32 b, for example, all have a flow channel depth in the flow direction of the oxidant gas. A depth variation portion 40 that is partially reduced is provided. In the oxidant gas flow path 30, a plurality of, for example, three depth varying portions 40 are formed in the flow path grooves 30 a on both ends in the width direction (arrow C direction) where the oxidant gas easily flows and the generated water tends to stay. Provided. In the oxidant gas flow channel 30, for example, two depth variation portions 40 are provided in the flow channel groove 30 a on the inner side in the width direction, and further, for example, one depth is formed in the flow channel groove 30 a on the inner side. A thickness variation unit 40 is provided. The depth changing portion 40 may not be provided in the flow channel 30a on the center side in the width direction. The number of the depth varying portions 40 decreases toward the center in the width direction of the oxidant gas flow path 30. The depth varying portions 40 are arranged in a staggered manner in the channel grooves 30a adjacent to each other in the flow direction of the channel grooves 30a.

  After the depth varying portion 40 is formed as an individual member, it is fixed to the cathode-side separator 14 by welding or adhesion. Note that the depth varying portion 40 may be integrally formed with the cathode separator 14. The depth varying portion 40 is preferably connected in a smooth R shape at the intersection with the surface of the cathode separator 14. The same applies to the anode separator 16 side.

  As shown in FIG. 4, the depth varying portion 40 includes a plurality of types of convex members 42 a, 42 b and 42 c having at least different height dimensions or shapes. As shown in FIGS. 4 and 5, the convex member 42 a is configured by a block body, is disposed in the flow channel groove 30 a, and projects in a cross-sectional mountain shape from the flow channel groove 30 a. The convex member 42a preferably has a symmetrical cross section. The convex member 42a has a top 42ae and is set to a depth D2 that is shallower than the depth D1 of the flow channel 30a (D1> D2).

  As shown in FIGS. 4 and 6, the convex member 42b is formed of a block body and is disposed in the flow channel groove 30a. The convex member 42b has a recess 42br cut out from the top of the mountain-shaped cross section protruding toward the flow channel groove 30a. Have. The convex member 42b preferably has a symmetrical cross section. The depth D3 of the convex member 42b is set to be shallower than the depth D1 of the flow channel groove 30a, and is set to be deeper than the depth D2 of the convex member 42a (D1> D3> D2).

  As shown in FIGS. 4 and 7, the convex member 42 c is configured by a block body, is disposed in the flow channel groove 30 a, and has a flat surface 42 cf protruding toward the flow channel groove 30 a. The depth D4 of the convex member 42c is set shallower than the depth D1 of the flow channel 30a, and is set deeper than the depth D2 of the convex member 42a and the depth D3 of the convex member 42b ( D1> D4> D3> D2). For example, the convex members 42a and the convex members 42b are alternately arranged in the gas flow direction in the flow channel 30a, while one convex member 42c is arranged in the flow channel 30a. The In addition, the depth fluctuation | variation part 40 is not limited to said convex-shaped member 42a-42c, The convex-shaped member from which 4 or more types of depth or shapes differ can be used.

  As shown in FIG. 3, in the inlet buffer portion 32a, the oxidant gas easily flows and the generated water stays in the upper side in the width direction (arrow C direction), that is, in the shortest connecting flow channel groove 36a. A plurality of, for example, three depth varying portions 40 are provided. In the long-side connecting flow channel groove 36a, two depth varying portions 40 may be provided, one depth varying portion 40 may be provided, or the depth varying portion 40 may not be provided. The depth variation unit 40 decreases the number from the upstream side toward the downstream side. The outlet buffer portion 32b side has the same shape as the inlet buffer portion 32a and has the same configuration.

  As shown in FIG. 8, a fuel gas flow path 44 that connects the fuel gas inlet communication hole 20 a and the fuel gas outlet communication hole 20 b is formed on the surface 16 a of the anode separator 16 facing the electrolyte membrane / electrode structure 12. Is done. The fuel gas channel 44 extends in the horizontal direction (arrow B direction), and has a plurality of linear (or wavy) channel grooves 44a that allow the fuel gas to flow in the long side direction along the separator surface.

  The channel groove 44a is formed between the convex portions 44b extending in parallel with each other in the arrow B direction. The convex portion 44b is provided so as to protrude toward the surface 16a by forming the anode separator 16 into a wave shape in the thickness direction.

  An inlet buffer portion 46 a is provided near the inlet of the fuel gas passage 44, and an outlet buffer portion 46 b is provided near the outlet of the fuel gas passage 44. The inlet buffer portion 46a has a substantially triangular shape along the shapes of the fuel gas inlet communication hole 20a and the oxidant gas outlet communication hole 18b, and a plurality of the inlet buffer portions 46a project toward the surface 16a in the vicinity of the fuel gas inlet communication hole 20a. Of embossing 48a.

  The inlet buffer portion 46a has a plurality of connecting flow channel grooves 50a that connect the inlet of the fuel gas flow channel 44 and the fuel gas inlet communication hole 20a. The connecting flow channel groove 50a is set so as to become longer in order from the upper side to the lower side of the anode separator 16. The connection channel groove 50a is formed between the connection convex portions 50b that are inclined downward in the direction of the arrow B and extend substantially parallel to each other. The connecting convex portion 50b is provided so as to protrude toward the surface 16a by forming the anode separator 16 into a wave shape in the thickness direction.

  The outlet buffer portion 46b has a substantially triangular shape along the shapes of the fuel gas outlet communication hole 20b and the oxidant gas inlet communication hole 18a, and a plurality of the outlet buffer portions 46b project toward the surface 16a in the vicinity of the fuel gas outlet communication hole 20b. Embossing 48b.

  The outlet buffer portion 46b has a plurality of connecting flow channel grooves 52a that allow the outlet of the fuel gas flow channel 44 and the fuel gas outlet communication hole 20b to communicate with each other. The connecting channel groove 52a is set so as to become shorter in order from the upper side to the lower side of the anode-side separator 16. The connection channel groove 52a is formed between the connection convex portions 52b that are inclined downward in the direction of the arrow B and extend substantially parallel to each other. The connecting convex portion 52b is provided so as to protrude toward the surface 16a by forming the anode separator 16 into a wave shape in the thickness direction.

  In the first embodiment, at least one, for example, all of the fuel gas flow path 44, the inlet buffer section 46a, and the outlet buffer section 46b have a partial flow path depth in the fuel gas flow direction. A depth variation unit 40 is provided which decreases to a minimum. The depth variation unit 40 is configured in the same manner as the oxidant gas flow path 30 side, and a detailed description thereof is omitted.

  As shown in FIG. 1, between the surface 16b of the anode-side separator 16 and the surface 14b of the cathode-side separator 14, cooling that communicates with the cooling medium inlet communication holes 22a, 22a and the cooling medium outlet communication holes 22b, 22b. A medium flow path 54 is formed. The cooling medium flow channel 54 circulates the cooling medium over the electrode range of the electrolyte membrane / electrode structure 12.

  In the anode-side separator 16, the cooling medium flow path 54 has a back surface shape of the fuel gas flow path 44, and in the cathode-side separator 14, the cooling medium flow path 54 has a back surface shape of the oxidant gas flow path 30.

  A first seal member 56 is integrally formed on the surfaces 14 a and 14 b of the cathode-side separator 14 around the outer peripheral edge of the cathode-side separator 14. A second seal member 58 is integrally formed on the surfaces 16 a and 16 b of the anode separator 16 around the outer peripheral edge of the anode separator 16. As the first seal member 56 and the second seal member 58, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion material Alternatively, an elastic seal member such as a packing material is used.

  The operation of the fuel cell 11 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 18a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 20a. Supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the pair of cooling medium inlet communication holes 22a.

  Therefore, as shown in FIGS. 1 and 3, the oxidant gas is introduced from the oxidant gas inlet communication hole 18a through the inlet buffer portion 32a into the oxidant gas flow path 30 of the cathode-side separator 14. The oxidant gas moves in the arrow B direction (horizontal direction) along the oxidant gas flow path 30 and is supplied to the cathode electrode 26 of the electrolyte membrane / electrode structure 12.

  On the other hand, as shown in FIG. 8, the fuel gas is supplied from the fuel gas inlet communication hole 20a to the fuel gas passage 44 of the anode separator 16 through the inlet buffer 46a. The fuel gas moves in the horizontal direction (arrow B direction) along the fuel gas flow path 44 and is supplied to the anode electrode 28 of the electrolyte membrane / electrode structure 12 (see FIG. 1).

  Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode electrode 26 and the fuel gas supplied to the anode electrode 28 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is called.

  Next, as shown in FIGS. 1 and 3, the oxidant gas supplied to the cathode electrode 26 of the electrolyte membrane / electrode structure 12 is consumed from the outlet buffer 32b along the oxidant gas outlet communication hole 18b. It is discharged in the direction of arrow A. On the other hand, the fuel gas supplied to and consumed by the anode electrode 28 of the electrolyte membrane / electrode structure 12 is discharged from the outlet buffer portion 46b in the direction of arrow A along the fuel gas outlet communication hole 20b as shown in FIG. Is done.

  The cooling medium supplied to the pair of cooling medium inlet communication holes 22 a is introduced into the cooling medium flow path 54 between the cathode side separator 14 and the anode side separator 16. As shown in FIG. 1, the cooling medium once flows in the direction of arrow C (gravity direction) and then moves in the direction of arrow B (horizontal direction) to cool the electrolyte membrane / electrode structure 12. This cooling medium moves outward in the direction of arrow C, and is then discharged to the pair of cooling medium outlet communication holes 22b.

  In this case, in the first embodiment, as shown in FIG. 3, a predetermined number of depth varying portions 40 are provided in the flow channel 30 a constituting the oxidant gas flow channel 30 as necessary. . The depth varying unit 40 includes, for example, convex members 42a, 42b, and 42c, and any or all of them are installed as necessary.

  For this reason, in the flow channel groove 30a, the flow channel depth of the portion where the depth varying portion 40 is provided is reduced from the maximum depth D1 to the shallower depth D2, D3, or D4. For example, as shown in FIG. 4, convex members 42 a, convex members 42 b, and convex members 42 a are alternately arranged in the flow channel 30 a, and the pressure loss (pressure loss) of the oxidant gas passing through these members. ) Is changing synchronously and increasing.

  Therefore, the pressure loss increasing portion is partially provided in the flow channel 30a. Thereby, in the channel groove 30a, the staying generated water and dew condensation water are discharged well by the increase / decrease in pressure loss, and the drainage can be easily improved. For this reason, with the simple and compact configuration, the produced water can be discharged well, and an effect that desired power generation performance can be secured is obtained.

  Furthermore, in the first embodiment, a predetermined number of depth varying portions 40 are provided in the connection flow channel grooves 36a and the connection flow channel grooves 38a constituting the inlet buffer portion 32a and the outlet buffer portion 32b, respectively, as necessary. It has been. In addition, in the inlet buffer section 32a, a plurality of, for example, three depth varying sections 40 are provided in the shortest connecting channel groove 36a in which the oxidant gas easily flows and the generated water easily stays. The number of the depth changing portions 40 decreases toward the center in the width direction of the inlet buffer portion 32a. The depth varying portions 40 are arranged in a staggered manner in the connecting flow channel grooves 36a adjacent to each other in the flow direction of the connecting flow channel grooves 36a. The same applies to the outlet buffer 32b.

  Therefore, in the connection flow path groove 36a and the connection flow path groove 38a, the staying generated water and dew condensation water are discharged well by increasing and decreasing the pressure loss, and the drainage performance can be easily improved. Thereby, with the simple and compact configuration, the produced water can be discharged well, and an effect that desired power generation performance can be secured is obtained.

  The fuel gas channel 44 is configured in the same manner as the oxidant gas channel 30 side. For this reason, the produced water and dew condensation water which are retained are discharged well by the increase / decrease in the pressure loss, and the drainage performance is easily improved, so that the same effect as that on the oxidant gas flow path 30 side can be obtained.

  FIG. 9 is an exploded perspective view of a main part of the fuel cell 62 constituting the fuel cell stack 60 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell 62 includes an electrolyte membrane / electrode structure 12, and a cathode separator 64 and an anode separator 66 that sandwich the electrolyte membrane / electrode structure 12. The cathode side separator 64 and the anode side separator 66 are made of, for example, a carbon separator, but may be made of a metal separator.

  An oxidant gas flow path 68 that connects the oxidant gas inlet communication hole 18 a and the oxidant gas outlet communication hole 18 b is formed on the surface 64 a of the cathode separator 64 facing the electrolyte membrane / electrode structure 12. The oxidant gas flow path 68 has meandering flow path grooves 68a having inversion portions on both ends in the direction of arrow B. The meandering channel groove 68a is formed between the meandering convex portions 68b.

  In the second embodiment, the depth varying portion 40 is provided in the meandering channel groove 68a. The installation site, the installation number, and the type of the depth varying unit 40 are set according to a location where the accumulated water is likely to accumulate, a location where the pressure loss is low, and the like.

  A fuel gas flow path 70 that connects the fuel gas inlet communication hole 20 a and the fuel gas outlet communication hole 20 b is formed on a surface 66 a of the anode separator 66 facing the electrolyte membrane / electrode structure 12. The fuel gas flow channel 70 has meandering flow channel grooves 70a having inversion portions on both ends in the direction of arrow B. The meandering channel groove 70a is formed between the meandering convex portions 70b.

  In the second embodiment, although not shown, the depth varying portion 40 is provided in the meandering channel groove 70a. The installation site, the installation number, and the type of the depth varying unit 40 are set according to a location where the accumulated water is likely to accumulate, a location where the pressure loss is low, and the like.

  In the second embodiment configured as described above, a predetermined number of depth varying portions 40 are provided in the meandering channel groove 68a constituting the oxidant gas channel 68 as necessary. For this reason, in the meandering channel groove 68a, a pressure loss increasing portion is partially provided, and the generated water and the dew condensation water staying in the meandering channel groove 68a are well discharged by increasing or decreasing the pressure loss. The same effects as those of the first embodiment can be obtained. The same applies to the fuel gas channel 70 side.

DESCRIPTION OF SYMBOLS 10, 60 ... Fuel cell stack 11 ... Fuel cell 12 ... Electrolyte membrane and electrode structure 14, 64 ... Cathode side separator 16, 66 ... Anode side separator 18a ... Oxidant gas inlet communication hole 18b ... Oxidant gas outlet communication hole 20a ... fuel gas inlet communication hole 20b ... fuel gas outlet communication hole 22a ... cooling medium inlet communication hole 22b ... cooling medium outlet communication hole 24 ... solid polymer electrolyte membrane 26 ... cathode electrode 28 ... anode electrodes 30, 68 ... oxidant gas flow Channels 30a, 44a ... Channel grooves 32a, 46a ... Inlet buffer portions 32b, 46b ... Outlet buffer portions 36a, 38a, 50a, 52a ... Connection channel grooves 40 ... Depth varying portions 42a-42c ... Convex members 44, 70 ... Fuel gas passage 54 ... Cooling medium passage 68a, 70a ... Meandering passage groove

Claims (3)

A reaction gas inlet having a fuel cell in which an electrolyte membrane / electrode structure provided with electrodes on both sides of the electrolyte membrane and a separator are stacked, and a plurality of the fuel cells are stacked and a reaction gas is circulated in the stacking direction A fuel cell stack in which a communication hole and a reaction gas outlet communication hole are formed,
The separator communicates with the reaction gas inlet communication hole and the reaction gas outlet communication hole, and a reaction gas flow path for allowing the reaction gas to flow along the separator surface;
A buffer unit having a plurality of connection channels each connected to the inlet side and the outlet side of the reaction gas channel;
Is provided,
At least the reactive gas flow path or the connection flow path of the buffer unit is provided with a depth varying portion in which the flow path depth partially decreases in the flow direction of the reactive gas. Battery stack.   2. The fuel cell stack according to claim 1, wherein a plurality of convex members are intermittently disposed at least in the reaction gas flow channel or the connection flow channel, whereby the flow channel depth is partially reduced. A fuel cell stack, wherein a plurality of the depth varying portions are provided.   3. The fuel cell stack according to claim 2, wherein the convex member includes at least a plurality of types of the convex members having different height dimensions or shapes.

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