JP5543828B2 - Fuel cell stack - Google Patents

Description

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a separator, a reaction gas flow path for flowing a reaction gas in an electrode surface direction, and the reaction gas of the separator. The present invention relates to a fuel cell stack including a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole that are circulated in a stacking direction are formed, and the plurality of power generation cells are stacked in a gravity direction with an electrode surface as a horizontal plane.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (an electrolyte / electrode structure) in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. ) (MEA) is provided with a unit cell (power generation cell) sandwiched between separators.

  This type of fuel cell is usually used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) of unit cells are stacked in order to obtain a desired power generation when used for in-vehicle use. Yes. In that case, the fuel cell stack generally includes a reaction gas flow channel for flowing a reaction gas along the electrode surface in the plane of the separator, and a reaction communicating with the reaction gas flow channel and penetrating in the stacking direction of the unit cells. A so-called internal manifold having a gas communication hole is employed.

  In this type of internal manifold type fuel cell stack, a current flows between the fuel cell stack and the ground (ground) through water droplets, so-called ground fault, or a current flows through the water droplets in the fuel cell stack. In order to prevent so-called liquid junction, it is necessary to ensure the insulation of the entire fuel cell system. Therefore, for example, a fuel cell system disclosed in Patent Document 1 is known.

  As shown in FIG. 10, this fuel cell system includes a fuel cell 1, and the fuel cell 1 includes a set of fuel cell stacks 2 housed in a stack case 3. The fuel cell stack 2 is provided side by side so that the cell modules 2a and 2b are fastened and held between the end plates 4a and 4b. Connected to the end plate 4a are supply pipes 5a, 6a and 7a for humidified hydrogen gas, humidified air and coolant, and discharge pipes 5b, 6b and 7b, respectively. These supply pipes 5a to 7a and discharge pipes 5b to 7b are formed of an electrically insulating member.

JP-A-2005-332673

  However, in the above-mentioned Patent Document 1, for example, the discharge pipes 5b and 6b through which hydrogen gas and air are discharged are formed of an electrically insulating member, but condensate water is connected from the cell modules 2a and 2b. There is a risk of being discharged. For this reason, a liquid junction is caused between the stacked cell modules 2a and 2b. In particular, when a metal separator is used as a separator, a corrosion current tends to be generated on the surface of the metal separator due to a potential difference.

  For this reason, there is a problem that the function of the electrolyte membrane is lowered through metal ions eluted by the corrosion of the metal separator, and the gas barrier function is lowered due to thinning (perforation) of the metal separator due to the corrosion. is there.

  The present invention solves this type of problem, and an object thereof is to provide a fuel cell stack capable of preventing liquid junctions between power generation cells as much as possible with a simple configuration.

The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a separator, a reaction gas flow path for flowing a reaction gas in an electrode surface direction, and the reaction gas of the separator. A solid polymer fuel comprising a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole that are circulated in a stacking direction are formed, and the plurality of power generation cells are stacked in a gravitational direction with an electrode surface as a horizontal plane It relates to a battery stack.

The fuel cell stack includes a piping member that forms a lower end portion of the reactive gas discharge communication hole or the reactive gas supply communication hole. The piping member is integrally formed on an inner peripheral surface of the piping member, and There is provided a water droplet blocking structure comprising at least one of a convex shape or a concave shape that blocks the connection of water droplets moving in the direction of gravity along the surface .

  In the fuel cell stack, a manifold member communicating with the piping member is preferably connected to a lower end portion in the stacking direction of the fuel cell stack.

Furthermore, it is preferable that the water droplet blocking structure includes a spiral groove formed integrally with the inner peripheral surface of the piping member.

Moreover, the water droplet blocking structure comprises a plurality of grooves are formed extending in the direction of gravity, the grooves are parallel along the circumferential direction of the inner peripheral surface on the inner circumferential surface of the pipe member Turkey And are preferred.

Moreover, it is preferable that the water droplet blocking structure includes a protruding portion that protrudes inward and is integrally formed so as to be inclined to the inner peripheral surface of the piping member.

Further, water droplets blocking structure is preferably provided with opening shape changing portion having a different aperture shape or different opening diameter and the pipe member.

  According to the present invention, the piping member forming the reactive gas discharge communication hole or the reactive gas supply communication hole is provided with a water droplet blocking structure for blocking the connection of water droplets. Therefore, the dew condensation water that moves in the gravity direction along the reaction gas discharge communication hole or the reaction gas supply communication hole is reliably disconnected outside the fuel cell stack under the action of the water droplet blocking structure. Discharged. Thereby, it becomes possible to prevent the occurrence of a liquid junction between the power generation cells as much as possible with a simple configuration.

1 is a schematic perspective explanatory view of a fuel cell stack according to a first embodiment of the present invention. It is a disassembled perspective explanatory drawing of the power generation cell which comprises the said fuel cell stack. FIG. 3 is a cross-sectional view of the fuel cell stack taken along line III-III in FIG. 2. It is a schematic perspective view from the lower end part of the fuel cell stack. FIG. 5 is a cross-sectional view of the fuel cell stack taken along line VV in FIG. 4. FIG. 4 is a partial cross-sectional clear view of a fuel cell stack according to a second embodiment of the present invention. FIG. 6 is a partial sectional clear view of a fuel cell stack according to a third embodiment of the present invention. It is a partial cross-section clear view of the fuel cell stack which concerns on the 4th Embodiment of this invention. FIG. 9 is a partial sectional clear view of a fuel cell stack according to a fifth embodiment of the present invention. 2 is an explanatory diagram of a fuel cell system disclosed in Patent Document 1. FIG.

  As shown in FIG. 1, the fuel cell stack 10 according to the first embodiment of the present invention includes a plurality of power generation cells (unit cells) 12 stacked in the direction of gravity (the direction of arrow A) with the electrode surface as a horizontal plane. A laminated body 14 is provided. At one end (upper end) in the stacking direction (arrow A direction) of the stacked body 14, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are disposed upward. A terminal plate 16b, an insulating plate 18b, and an end plate 20b are disposed downward at the other end (lower end) of the stacked body 14 in the stacking direction.

  Both ends of a plurality of connecting bars 21 are fixed to the end plates 20a and 20b, and a tightening load is applied between the end plates 20a and 20b in the stacking direction. A tightening load may be applied between the end plates 20a and 20b in the stacking direction via a tie rod (not shown), or a tightening load may be applied in the stacking direction via a box-shaped casing.

  As shown in FIGS. 2 and 3, each power generation cell 12 includes an electrolyte membrane / electrode structure (MEA) 22, and a first metal separator 24 and a second metal separator 26 that sandwich the electrolyte membrane / electrode structure 22. With.

  The first metal separator 24 and the second metal separator 26 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a vertically long metal plate having a surface treated for anticorrosion on the metal surface. The first and second metal separators 24 and 26 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing a metal thin plate into a corrugated plate shape. Instead of the first metal separator 24 and the second metal separator 26, for example, a carbon separator (not shown) may be used.

  As shown in FIG. 2, an oxidant for supplying an oxidant gas, for example, an oxygen-containing gas, to one end edge of the power generation cell 12 in the arrow B direction (horizontal direction) in communication with each other in the arrow A direction Gas supply communication hole (reaction gas supply communication hole) 28a, cooling medium supply communication hole 30a for supplying a cooling medium, and fuel gas discharge communication hole (reactive gas discharge for discharging a hydrogen-containing gas, for example) (Communication hole) 32b is provided.

  The other end edge of the power generation cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, discharges a fuel gas supply communication hole (reaction gas supply communication hole) 32a for supplying fuel gas, and discharges the cooling medium. A cooling medium discharge communication hole 30b for the purpose and an oxidant gas discharge communication hole (reactive gas discharge communication hole) 28b for discharging the oxidant gas are provided.

  On the surface 24a of the first metal separator 24 on the electrolyte membrane / electrode structure 22 side, for example, an oxidant gas flow path 36 extending in the arrow B direction (electrode surface direction) is provided. The oxidant gas flow path 36 communicates with the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b. A cooling medium flow path 38 is formed on the surface 24 b opposite to the surface 24 a of the first metal separator 24. The cooling medium flow path 38 communicates with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b.

  The surface 26a of the second metal separator 26 on the electrolyte membrane / electrode structure 22 side communicates with the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b and extends in the direction of arrow B (electrode surface direction). A fuel gas flow path 40 is formed. The cooling medium flow communicating with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b is overlapped with the surface 24b of the first metal separator 24 on the surface 26b opposite to the surface 26a of the second metal separator 26. A path 38 is formed.

  In the first metal separator 24, the first seal member 42 is integrally injection-molded on the metal thin plate, and in the second metal separator 26, the second seal member 44 is integrally injection-molded on the metal thin plate.

  The first and second sealing members 42 and 44 are, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, acrylic rubber, or other sealing materials, cushion materials, Alternatively, a packing material is used.

  The first seal member 42 communicates the oxidant gas supply communication hole 28 a and the oxidant gas discharge communication hole 28 b to the oxidant gas flow path 36 on the surface 24 a side of the first metal separator 24. The first seal member 42 is integrally formed with an inlet side bridge portion 46a and an outlet side bridge portion 46b so as to be close to the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b, respectively.

  The second seal member 44 communicates the fuel gas supply communication hole 32 a and the fuel gas discharge communication hole 32 b with the fuel gas flow path 40 on the surface 26 a side of the second metal separator 26. In the second seal member 44, an inlet-side bridge portion 48a and an outlet-side bridge portion 48b are integrally formed adjacent to the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b, respectively.

  The second seal member 44 communicates the cooling medium supply communication hole 30 a, the cooling medium discharge communication hole 30 b, and the cooling medium flow path 38 on the surface 26 b side of the second metal separator 26. In the second seal member 44, an inlet side bridge portion 50a and an outlet side bridge portion 50b are integrally formed adjacent to the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b, respectively.

  As shown in FIGS. 2 and 3, the electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane (electrolyte) 52 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane. A cathode-side electrode 54 and an anode-side electrode 56 sandwiching 52.

  The cathode side electrode 54 and the anode side electrode 56 are formed by uniformly applying a gas diffusion layer 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. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 52.

  As shown in FIG. 4, an oxidant gas supply communication hole 28a, a cooling medium supply communication hole 30a, a fuel gas discharge communication hole 32b, and a fuel gas supply communication are provided on the end plate 20b, which is the lower end of the fuel cell stack 10 in the stacking direction. Manifold members 60a, 62a, 64b, 64a, 62b, and 60b are provided in communication with the hole 32a, the cooling medium discharge communication hole 30b, and the oxidant gas discharge communication hole 28b, respectively.

  The end plate 20b includes supply pipes (pipe members) 66a, 66b, and 66c that form an oxidant gas supply communication hole 28a, a cooling medium supply communication hole 30a, and a fuel gas supply communication hole 32a, and an oxidant gas discharge communication hole 28b. The discharge pipes (pipe members) 68a, 68b and 68c forming the cooling medium discharge communication hole 30b and the fuel gas discharge communication hole 32b are connected.

  As shown in FIG. 5, the discharge pipe 68a is inserted into the end plate 20b and penetrates in the direction of gravity to form the lower end portion of the oxidant gas discharge communication hole 28b. On the inner peripheral surface of the discharge pipe 68a, a water droplet blocking structure for blocking the connection of the water droplet W, for example, a spiral groove portion 70 is provided.

  The other discharge pipes 68b and 68c and the supply pipes 66a to 66c are configured in the same manner as the discharge pipe 68a described above, and a detailed description thereof is omitted. Further, a water droplet blocking structure may be used only at least for the discharge pipes 68a to 68c.

  The operation of the fuel cell stack 10 configured as described above will be described below.

  First, as shown in FIG. 4, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 28a via the manifold member 60a of the end plate 20b, and the fuel is supplied via the manifold member 64a. A fuel gas such as a hydrogen-containing gas is supplied to the gas supply communication hole 32a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium supply communication hole 30a through the manifold member 62a.

  Therefore, the oxidant gas is introduced into the oxidant gas flow path 36 provided in the first metal separator 24 from the oxidant gas supply communication hole 28a as shown in FIG. As a result, the oxidant gas is supplied to the cathode side electrode 54 constituting the electrolyte membrane / electrode structure 22 while moving in the direction of the arrow B in the oxidant gas flow path 36.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 40 provided in the second metal separator 26 from the fuel gas supply communication hole 32a. The fuel gas introduced into the fuel gas flow path 40 is supplied to the anode side electrode 56 constituting the electrolyte membrane / electrode structure 22 while moving in the arrow B direction.

  Therefore, in the electrolyte membrane / electrode structure 22, the oxidant gas supplied to the cathode side electrode 54 and the fuel gas supplied to the anode side electrode 56 are consumed by an electrochemical reaction in the electrode catalyst layer, thereby generating power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode-side electrode 54 is discharged to the oxidant gas discharge communication hole 28b. On the other hand, the used fuel gas consumed by being supplied to the anode electrode 56 is discharged to the fuel gas discharge communication hole 32b.

  The cooling medium flows in the direction of arrow B after being introduced into the cooling medium flow path 38 from the cooling medium supply communication hole 30a. The cooling medium is discharged to the cooling medium discharge communication hole 30b after the electrolyte membrane / electrode structure 22 is cooled.

  By the way, in the oxidant gas flow path 36, the oxidant gas sent from the oxidant gas supply communication hole 28a is used by the power generation reaction and water is generated. The generated water is discharged to the oxidant gas discharge communication hole 28b along with the used oxidant gas.

  In this case, in the first embodiment, for example, as shown in FIG. 5, on the inner peripheral surface of the discharge pipe 68 a that forms the lower end portion of the oxidant gas discharge communication hole 28 b, a spiral that forms a water droplet blocking structure is formed. A groove portion 70 is provided. For this reason, the dew condensation water W that moves in the direction of gravity along the oxidant gas discharge communication hole 28b along with the used oxidant gas flows under the action of the spiral groove 70, that is, the inner periphery of the discharge pipe 68a. Under the action of the long concave-convex shape portion extending spirally along the surface, the continuity (connection) is cut off and reliably discharged into the manifold member 60b.

  Therefore, with a simple configuration, it is possible to prevent as much as possible the occurrence of a so-called liquid junction in which a current flows between the power generation cells 12 via water droplets. Thereby, especially the 1st metal separator 24 and the 2nd metal separator 26 do not generate | occur | produce the corrosion current by an electrical potential difference, and can prevent the fall of the gas interruption | blocking function by thickness reduction well. For this reason, the effect that it becomes possible to use each electric power generation cell 12 efficiently and satisfactorily for a long period of time is acquired.

  Moreover, as shown in FIG. 4, the spiral groove part 70 is similarly provided in the internal peripheral surface of the discharge piping 68c which forms the lower end part of the fuel gas discharge communicating hole 32b. Therefore, the condensed water W that moves in the direction of gravity along the fuel gas discharge communication hole 32b is blocked by the spiral groove 70, and the continuity is satisfactorily cut off, thereby preventing liquid junction.

  The end plate 20b is provided with supply pipes 66a and 66c that form the oxidant gas supply communication hole 28a and the fuel gas supply communication hole 32a. For this reason, the condensed water that moves in the gravity direction along the oxidant gas supply communication hole 28a and the condensed water W that moves in the gravity direction along the fuel gas supply communication hole 32a have good continuity, respectively. Entanglement can be prevented.

  FIG. 6 is a partial cross-sectional explanatory view of a fuel cell stack 80 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. Similarly, in the third and subsequent embodiments described below, detailed description thereof is omitted.

  Here, in the second and subsequent embodiments, only the oxidant gas discharge communication hole 28b will be described, but it goes without saying that other communication holes are similarly configured.

  In the fuel cell stack 80, the end plate 20b is provided with a discharge pipe 82 that forms the lower end of the oxidant gas discharge communication hole 28b. On the inner peripheral surface of the discharge pipe 82, a plurality of groove portions 84 that form a water droplet blocking structure and are formed in parallel in the direction of gravity are formed.

  Accordingly, since the concave and convex portion extending in the direction of gravity is provided on the inner peripheral surface of the discharge pipe 82, the condensed water W descending while circling along the oxidant gas discharge communication hole 28b has good continuity. The same effects as those of the first embodiment can be obtained, such as being able to prevent liquid junctions.

  FIG. 7 is a partial cross-sectional explanatory view of a fuel cell stack 90 according to the third embodiment of the present invention.

  The fuel cell stack 90 includes a discharge pipe 92 that is attached to the end plate 20b and forms the lower end portion of the oxidant gas discharge communication hole 28b. On the inner peripheral surface of the discharge pipe 92, a water droplet blocking structure is formed, and a ring-shaped protrusion 94 protruding inward is formed.

  FIG. 8 is a partial cross-sectional explanatory view of a fuel cell stack 100 according to the fourth embodiment of the present invention.

  The fuel cell stack 100 includes a discharge pipe 102 that is attached to the end plate 20b and forms the lower end of the oxidant gas discharge communication hole 28b. On the inner peripheral surface of the discharge pipe 102, a water droplet blocking structure is formed, and a tapered protrusion 104 that protrudes inwardly is formed.

  FIG. 9 is a partial cross-sectional explanatory view of a fuel cell stack 110 according to the fifth embodiment of the present invention.

  The fuel cell stack 110 includes a discharge pipe 112 that is attached to the end plate 20b and forms a lower end portion of the oxidant gas discharge communication hole 28b. A lower portion of the discharge pipe 112 is provided with an opening shape changing portion 114 that constitutes a water droplet blocking structure and changes the opening shape of the discharge pipe 112. The discharge pipe 112 has an opening shape with a circular cross section, for example, while the opening shape changing unit 114 is set to a small circular shape, an elliptical shape, or the like in addition to a polygonal shape such as a rectangular shape or a triangular shape.

  In the third to fifth embodiments configured as described above, various water droplet blocking structures are configured at the lower end of the oxidant gas discharge communication hole 28b. For this reason, the effect similar to said 1st and 2nd embodiment is acquired, such as the continuity of the condensed water W being interrupted | blocked favorably and a liquid junction being able to be blocked | prevented.

DESCRIPTION OF SYMBOLS 10, 80, 90, 100, 110 ... Fuel cell stack 12 ... Power generation cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulating plate 20a, 20b ... End plate 22 ... Electrolyte membrane and electrode structure 24, 26 ... Metal separator 28a ... Oxidant gas supply communication hole 28b ... Oxidant gas discharge communication hole 30a ... Cooling medium supply communication hole 30b ... Cooling medium discharge communication hole 32a ... Fuel gas supply communication hole 32b ... Fuel gas discharge communication hole 36 ... Oxidation Agent gas flow path 38 ... Cooling medium flow path 40 ... Fuel gas flow path 42, 44 ... Seal member 52 ... Solid polymer electrolyte membrane 54 ... Cathode side electrode 56 ... Anode side electrodes 60a, 60b, 62a, 62b, 64a, 64b ... Manifold members 66a to 66c ... Supply piping 68a to 68c, 82, 92, 102, 112 ... Discharge distribution Pipe 70 ... spiral groove 84 ... groove 94, 104 ... projection 114 ... opening shape changing part

Claims (7)

An electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of the electrolyte and a separator are stacked, a reaction gas flow path for flowing a reaction gas in the electrode surface direction, and a flow of the reaction gas in the stacking direction of the separator A solid polymer fuel cell stack including a power generation cell in which a reaction gas supply communication hole and a reaction gas discharge communication hole to be formed are formed, and the plurality of power generation cells are stacked in a gravitational direction with an electrode surface as a horizontal plane. And
A piping member that forms a lower end portion of the reaction gas discharge communication hole or the reaction gas supply communication hole;
The piping member is formed integrally with the inner peripheral surface of the piping member, and has a water droplet blocking structure formed of at least one of a convex shape and a concave shape that blocks a connection of water droplets moving in the direction of gravity along the inner peripheral surface. A fuel cell stack.   2. The fuel cell stack according to claim 1, wherein a manifold member communicating with the piping member is connected to a lower end portion in the stacking direction of the fuel cell stack. The fuel cell stack according to claim 2, wherein an end plate to which the manifold member is attached is disposed at a lower end portion in the stacking direction of the fuel cell stack .
The fuel cell stack, wherein the piping member is inserted into the end plate.   4. The fuel cell stack according to claim 1, wherein the water droplet blocking structure includes a spiral groove formed integrally with an inner peripheral surface of the piping member. 5. .   The fuel cell stack according to any one of claims 1 to 3, wherein the water droplet blocking structure includes a plurality of grooves formed to extend in a gravitational direction on the inner peripheral surface of the piping member, A fuel cell stack, wherein the groove portions are arranged in parallel along the circumferential direction of the inner peripheral surface.   4. The fuel cell stack according to claim 1, wherein the water droplet blocking structure includes a protruding portion that protrudes inward so as to incline toward an inner peripheral surface of the piping member. A fuel cell stack characterized by The fuel cell stack according to claim 1, wherein the water droplets blocking structure is characterized in that an opening shape changing portion having a different aperture shape or different opening diameter and the pipe member Fuel cell stack.

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