JP2008293743A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable uniform reactant gas supply from a reactant gas communicating hole to the whole surface of a reactant gas passage, and to secure desired power generation performance, using a simple structure. <P>SOLUTION: A fuel cell 10 includes a first metallic separator 18 and a second metallic separator 20, between which an electrolyte membrane-electrode structure 16 is held. The first metallic separator 18 is provided with an inlet buffer portion 36a, which communicates with the upstream of a fuel gas passage 34 and has a generally triangular shape and width dimension which is comparable to that of the fuel gas passage 34. An embossment 38a of the inlet buffer portion 36a is set so that the arrangement density at the center side of the inlet buffer portion 36a is lower than that at the end side of the inlet buffer portion 36a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are laminated, and a reaction gas flow path for supplying a reaction gas is formed along the electrode surface. The present invention relates to a fuel cell in which a reaction gas communication hole for flowing gas in a stacking direction is formed.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane is sandwiched by separators. It has a power generation cell. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of power generation cells.

  In the fuel cell described above, a fuel gas flow path (hereinafter also referred to as a reaction gas flow path) for flowing a fuel gas to the anode side electrode and an oxidation for flowing an oxidant gas to the cathode side electrode in the plane of the separator. An agent gas channel (hereinafter also referred to as a reaction gas channel) is provided. Furthermore, a cooling medium flow path for flowing a cooling medium is provided along the surface direction of the separator for each power generation cell or for each of the plurality of power generation cells.

  The fuel cell may constitute a so-called internal manifold in which a reaction gas communication hole and a cooling medium communication hole penetrating in the stacking direction of the separator are provided inside the fuel cell. At this time, generally, a buffer portion is provided between the reaction gas communication hole and the reaction gas channel so as to uniformly distribute and supply the reaction gas to the reaction gas channel.

  For example, the fuel cell disclosed in Patent Document 1 includes a separator 1 as shown in FIG. The separator 1 flows gas along the gas inflow portion 2, the electromotive portion inflow portion 3, the electromotive portion, the electromotive portion outflow portion 4, and the gas outflow portion 5. In the separator 1, trapezoidal fin groups 7 a, 7 b and 7 c are arranged in the gas flow path 6 as flow path resistance members. And the pressure of the gas in the electromotive part inflow part 3 is set so that it may become substantially constant by setting each arrangement | positioning angle of the trapezoid fin group 7a-7c.

JP-A-6-267559

  However, in Patent Document 1 described above, the arrangement direction (angle) of each trapezoidal fin constituting the trapezoidal fin groups 7a to 7c must be set, and the configuration becomes complicated. Moreover, the trapezoidal fin groups 7a to 7c are arranged in a region slightly beyond the central portion from one end portion in the width direction (arrow H direction) of the electromotive portion. Therefore, although the gas supplied from the gas inflow part 2 to the gas flow path 6 is supplied to the one end part side of the power generation part, it is difficult to supply it to the other end part side of the power generation part. Thereby, there exists a problem that gas cannot flow uniformly over the whole electric power generation part.

  The present invention solves this type of problem, and with a simple configuration, the reaction gas can be uniformly supplied from the reaction gas communication hole to the entire surface of the reaction gas flow path, thereby ensuring the desired power generation performance. An object is to provide a possible fuel cell.

  In the present invention, an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are laminated, and a reaction gas flow path for supplying a reaction gas is formed along the electrode surface. The present invention relates to a fuel cell in which a reaction gas communication hole for flowing gas in a stacking direction is formed.

  The separator is located on the inlet side of the reaction gas channel, and has a substantially triangular inlet buffer portion having a width dimension equivalent to that of the reaction gas channel, and the reaction located on one ridge line side of the inlet buffer portion. A gas communication hole supply side is provided. The inlet buffer unit has a plurality of convex portions, and the convex portions are arranged such that the arrangement density on the central portion side of the inlet buffer portion is sparse compared to the arrangement density on the end side of the inlet buffer portion. Is set to

  The separator is positioned on the outlet side of the reaction gas flow path, and has a substantially triangular outlet buffer portion having a width dimension equivalent to that of the reaction gas flow path, the supply side of the reaction gas communication hole, and the position of the point target And the outlet side of the reaction gas communication hole located on one ridge line side of the outlet buffer portion is provided, the outlet buffer portion has a plurality of convex portions, and the convex portion is the outlet It is preferable that the arrangement density on the central side of the buffer unit is set so as to be sparse compared to the arrangement density on the end side of the outlet buffer unit.

  According to the present invention, the arrangement density of the projections on the center side of the inlet buffer unit is set so as to be sparser than the arrangement density of the projections on the end side of the inlet buffer unit. Accordingly, the arrangement density of the protrusions is sparse particularly in the width direction central portion side of the inlet buffer portion where the reaction gas easily passes, so that the flow rate of the reaction gas is reduced and the reaction gas is reduced to the width of the reaction gas flow path. It can guide to the channel groove of the direction center part side.

  Moreover, the inlet buffer section has a width dimension equivalent to that of the reaction gas flow path. For this reason, it becomes possible to distribute and supply the reaction gas over the entire length in the width direction of the reaction gas channel from the inlet buffer. Accordingly, the reaction gas can be supplied uniformly and smoothly from the reaction gas communication hole to the entire surface of the reaction gas flow path with a simple configuration, and desired power generation performance can be ensured.

  FIG. 1 is an exploded schematic perspective view of a fuel cell 10 according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory view of the fuel cell 10 taken along line II-II in FIG.

  As shown in FIG. 1, in the fuel cell 10, an electrolyte membrane / electrode structure 16 is sandwiched between a first metal separator 18 on the anode side and a second metal separator 20 on the cathode side. The first and second metal separators 18 and 20 have a concavo-convex shape by pressing a metal thin plate into a wave shape.

  The first and second metal separators 18 and 20 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface is subjected to anticorrosion treatment. Moreover, instead of the first and second metal separators 18 and 20, for example, a carbon separator may be adopted.

  An oxidant gas supply for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the direction of the arrow A at the upper edge of the long side direction (the direction of arrow C in FIG. 1) of the fuel cell 10. A communication hole (reaction gas communication hole) 22a and a fuel gas supply communication hole (reaction gas communication hole) 24a for supplying a fuel gas, for example, a hydrogen-containing gas, are provided.

  The lower end edge of the long side direction of the fuel cell 10 communicates with each other in the direction of the arrow A, and a fuel gas discharge communication hole (reaction gas communication hole) 24b for discharging the fuel gas and an oxidant gas are discharged. An oxidant gas discharge communication hole (reaction gas communication hole) 22b is provided. The oxidant gas supply communication hole 22a and the oxidant gas discharge communication hole 22b are provided corresponding to the positions to be pointed, and the fuel gas supply communication hole 24a and the fuel gas discharge communication hole 24b are similarly pointed. Are provided corresponding to the positions.

  At one edge of the fuel cell 10 in the short side direction (arrow B direction), there is provided a cooling medium supply communication hole 26a that communicates with each other in the arrow A direction and supplies a cooling medium. A cooling medium discharge communication hole 26b for discharging the cooling medium is provided at the other end edge.

  The electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 28 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 30 and a cathode side electrode 32 that sandwich the solid polymer electrolyte membrane 28. With. The anode side electrode 30 has a smaller surface area than the cathode side electrode 32.

  The anode-side electrode 30 and the cathode-side electrode 32 are uniformly coated with 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. An electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 28.

  A fuel gas flow path 34 that connects the fuel gas supply communication hole 24 a and the fuel gas discharge communication hole 24 b is formed on the surface 18 a of the first metal separator 18 facing the electrolyte membrane / electrode structure 16. As shown in FIG. 3, the fuel gas channel 34 has a plurality of wave-like channel grooves 34a extending in the direction of arrow C, and is located at the upper and lower ends of the wave-like channel groove 34a in the direction of arrow C. An inlet buffer part 36a and an outlet buffer part 36b are provided.

  The inlet buffer portion 36a and the outlet buffer portion 36b have a substantially triangular shape and are set to have the same width dimension (dimension in the direction of arrow B) as the fuel gas flow path 34. The fuel gas supply communication hole 24a is located along one ridge line side of the inlet buffer portion 36a (in the direction of arrow B1), and the fuel gas discharge communication hole 24b is one ridge line of the outlet buffer portion 36b (in the direction of arrow B2). Located along the side.

  The inlet buffer portion 36a and the outlet buffer portion 36b have a plurality of embossed (convex portions) 38a and 38b. The embossing 38a has an arrangement density on the central portion (arrow B direction central portion) side of the inlet buffer portion 36a to an arrangement density on the end portion (arrow B1 direction end portion and arrow B2 direction end portion) side of the inlet buffer portion 36a. It is set so as to be sparse.

  The surface 18a of the first metal separator 18 has a plurality of receiving portions 41a for forming a communication path that communicates the fuel gas supply communication hole 24a and the inlet buffer portion 36a, a fuel gas discharge communication hole 24b, and an outlet buffer portion 36b. And a plurality of receiving portions 41b for forming communication passages communicating with each other. A plurality of supply hole portions 42a and discharge hole portions 42b are formed in the vicinity of the receiving portions 41a and 41b, respectively. The supply hole portion 42a communicates with the fuel gas supply communication hole 24a on the surface 18b side, while the discharge hole portion 42b similarly communicates with the fuel gas discharge communication hole 24b on the surface 18b side.

  As shown in FIG. 4, an oxidant gas supply communication hole 22a and an oxidant gas discharge communication hole 22b are communicated with the surface 20a of the second metal separator 20 facing the electrolyte membrane / electrode structure 16 through an oxidant gas. A flow path 44 is formed. The oxidant gas channel 44 has a plurality of wave-like channel grooves 44a extending in the direction of the arrow C, and is located at the upper and lower ends of the wave-like channel groove 44a in the direction of the arrow C. A buffer unit 46b is provided.

  The inlet buffer portion 46 a and the outlet buffer portion 46 b have a substantially triangular shape, and are set to have a width dimension (dimension in the arrow B direction) equivalent to that of the oxidant gas flow path 44. The oxidant gas supply communication hole 22a is located along the ridge line side of one of the inlet buffer portions 46a (in the direction of arrow B2), and the oxidant gas discharge communication hole 22b is one of the outlet buffer portions 46b (in the direction of arrow B1). ) Along the ridgeline side.

  The inlet buffer portion 46a and the outlet buffer portion 46b have a plurality of embossments (convex portions) 48a and 48b. The embossing 48a has an arrangement density on the side of the central portion (arrow B direction central portion) side of the inlet buffer portion 46a, on the end portion (arrow B1 direction end portion and arrow B2 direction end portion) side of the inlet buffer portion 46a. It is set so as to be sparse.

  On the surface 20a of the second metal separator 20, a plurality of receiving portions 51a for forming a communication path that communicates the oxidant gas supply communication hole 22a and the inlet buffer portion 46a, an oxidant gas discharge communication hole 22b, and an outlet buffer portion. A plurality of receiving portions 51b for forming communication passages communicating with 46b are provided.

  As shown in FIG. 1, the cooling medium communicating with the cooling medium supply communication hole 26 a and the cooling medium discharge communication hole 26 b between the surface 20 b of the second metal separator 20 and the surface 18 b of the first metal separator 18. A flow path 54 is formed. The cooling medium channel 54 is formed to extend in the direction of arrow B by overlapping the back surface shape of the fuel gas channel 34 and the back surface shape of the oxidant gas channel 44.

  A first seal member 56 is integrally formed on the surfaces 18 a and 18 b of the first metal separator 18 around the outer peripheral edge of the first metal separator 18. A second seal member 58 is integrally formed on the surfaces 20 a and 20 b of the second metal separator 20 so as to go around the outer peripheral edge of the second metal separator 20. As the first and second sealing members 56, 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, a packing material is used.

  As shown in FIGS. 1 and 3, the first seal member 56 includes a seal portion 56a provided on the surface 18a side so as to surround the fuel gas flow path 34, and a seal portion 56b provided outside the seal portion 56a. And have. The seal portion 56a constitutes a convex seal that goes around the fuel gas flow path 34, the inlet buffer portion 36a, the outlet buffer portion 36b, the supply hole portion 42a, and the discharge hole portion 42b.

  As shown in FIG. 4, the second seal member 58 is formed on the surface 20a side of the second metal separator 20 with the oxidant gas flow path 44, the inlet buffer part 46a, the outlet buffer part 46b, the oxidant gas supply communication hole 22a, and the oxidation gas. A seal portion 58a is formed so as to surround the agent gas discharge communication hole 22b.

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

  First, as shown in FIG. 1, in the fuel cell 10, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 22a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply communication hole 24a. Is supplied. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 26a.

  The oxidant gas is introduced into the oxidant gas flow path 44 of the second metal separator 20 from the oxidant gas supply communication hole 22a and moves vertically downward along the cathode side electrode 32 of the electrolyte membrane / electrode structure 16. .

  At that time, as shown in FIG. 4, on the surface 20a of the second metal separator 20, the oxidant gas flowing through the oxidant gas supply communication hole 22a is supplied to the inlet buffer part 46a through the plurality of receiving parts 51a. The The oxidant gas supplied to the inlet buffer 46a is dispersed in the direction of arrow B and flows vertically downward along the plurality of undulating channel grooves 44a constituting the oxidant gas channel 44. It is supplied to the cathode side electrode 32 of the membrane / electrode structure 16.

  On the other hand, as shown in FIGS. 1 and 3, the fuel gas is supplied to the surface 18 a side through the plurality of supply holes 42 a from the fuel gas supply communication holes 24 a on the surface 18 b of the first metal separator 18. The fuel gas is introduced into the inlet buffer portion 36a through the receiving portion 41a. The fuel gas dispersed in the direction of the arrow B by the inlet buffer portion 36a moves vertically downward along the plurality of wave-like channel grooves 34a constituting the fuel gas channel 34, and the anode of the electrolyte membrane / electrode structure 16 It is supplied to the side electrode 30.

  Therefore, in each electrolyte membrane / electrode structure 16, the oxidant gas supplied to the cathode side electrode 32 and the fuel gas supplied to the anode side electrode 30 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed (see FIG. 2).

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 32 is sent to an outlet buffer part 46 b communicating with the lower part of the oxidant gas flow path 44 as shown in FIG. 4. Further, the oxidant gas is discharged from the outlet buffer part 46b to the oxidant gas discharge communication hole 22b along the space between the plurality of receiving parts 51b.

  Similarly, as shown in FIGS. 1 and 3, the fuel gas that is consumed by being supplied to the anode electrode 30 is sent to an outlet buffer portion 36 b that communicates with the lower portion of the fuel gas flow path 34, and then a plurality of fuel gases are supplied. It flows between the receiving parts 41b. The fuel gas passes through the plurality of discharge holes 42b and moves toward the surface 18b, and is discharged to the fuel gas discharge communication hole 24b.

  The cooling medium flows in the direction of arrow B (horizontal direction) after being introduced into the cooling medium flow path 54 between the first and second metal separators 18 and 20 from the cooling medium supply communication hole 26a. The cooling medium is discharged from the cooling medium discharge communication hole 26b after the electrolyte membrane / electrode structure 16 is cooled.

  In this case, in the first embodiment, as shown in FIG. 3, the inlet buffer portion 36 a has a substantially triangular shape and is set to have a width dimension equivalent to that of the fuel gas flow path 34. The arrangement density of the emboss 38a on the center side of the inlet buffer 36a is set so as to be sparse compared to the arrangement density of the emboss 38a on the end of the inlet buffer 36a.

  Therefore, when the fuel gas supplied from the fuel gas supply communication hole 24a through the supply hole 42a to the inlet buffer 36a is dispersed in the direction of the arrow B2 along the inlet buffer 36a, the fuel gas is particularly The flow velocity of the fuel gas decreases at the center in the width direction of the inlet buffer portion 36a that easily passes. Therefore, the fuel gas is smoothly supplied to the wave-like channel groove 34a of the fuel gas channel 34 from the widthwise center portion side of the inlet buffer portion 36a.

  Moreover, the inlet buffer portion 36 a has a width dimension equivalent to that of the fuel gas flow path 34. Therefore, the fuel gas can be distributed and supplied from the inlet buffer portion 36a over the entire length in the width direction of the fuel gas flow path 34. As a result, the fuel gas can be uniformly and smoothly supplied to the entire surface of the fuel gas flow path 34 from the fuel gas supply communication hole 24a with a simple configuration, and the desired power generation performance can be ensured. can get.

  As shown in FIG. 4, the inlet buffer portion 46a, which is set to have a width dimension equivalent to that of the oxidant gas flow path 44, has an arrangement density of the embosses 48a on the center side in the width direction of the inlet buffer portion 46a. It is set so as to be sparse compared to the arrangement density of the embossing 48a on the end side. Accordingly, there is an advantage that the oxidant gas can be uniformly supplied from the inlet buffer portion 46 a over the entire width direction of the oxidant gas flow path 44.

  FIG. 5 is an exploded schematic perspective view of a fuel cell 60 according to the second embodiment of the present invention. Note that the same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the fuel cell 60, the electrolyte membrane / electrode structure 16 is sandwiched between a first metal separator 62 on the anode side and a second metal separator 64 on the cathode side. The first metal separator 62 has an outlet buffer part 36b, and the embossing 38b of the outlet buffer part 36b has an arrangement density on the side of the center part in the width direction of the outlet buffer part 36b. It is set to be sparse compared to the arrangement density of.

  As shown in FIG. 6, the second metal separator 64 has an outlet buffer portion 46b, and the emboss 48b constituting the outlet buffer portion 46b has an arrangement density on the central side of the outlet buffer portion 46b. It is set so as to be sparse compared with the arrangement density of the buffer unit 46b.

  Thereby, in 2nd Embodiment, the smooth flow to the arrow B direction of the fuel gas and oxidizing gas in outlet buffer part 36b, 46b is obtained. Therefore, the fuel gas and the oxidant gas can flow uniformly and smoothly over the entire surfaces of the fuel gas flow path 34 and the oxidant gas flow path 44, and it is possible to obtain a desired power generation performance.

  In the first and second embodiments, the fuel gas flow path 34 and the oxidant gas flow path 44 are configured by the plurality of wave-shaped flow path grooves 34a and 44a. However, the present invention is not limited to this. Even if it is constituted by a plurality of linear channel grooves, the same effect can be obtained.

1 is an exploded schematic perspective view of a fuel cell 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 a front view of the 1st metal separator which comprises the said fuel cell. It is a front view of the 2nd metal separator which comprises the said fuel cell. It is a disassembled schematic perspective view of the fuel cell which concerns on the 2nd Embodiment of this invention. It is front explanatory drawing of the 2nd metal separator which comprises the said fuel cell. It is explanatory drawing of the separator of patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 60 ... Fuel cell 16 ... Electrolyte membrane electrode assembly 18, 20, 62, 64 ... Metal separator 22a ... Oxidant gas supply communication hole 22b ... Oxidant gas discharge communication hole 24a ... Fuel gas supply communication hole 24b ... Fuel Gas discharge communication hole 26a ... Cooling medium supply communication hole 26b ... Cooling medium discharge communication hole 28 ... Solid polymer electrolyte membrane 30 ... Anode side electrode 32 ... Cathode side electrode 34 ... Fuel gas flow path 34a, 44a ... Wave-shaped flow path groove 36a , 46a ... Inlet buffer part 36b, 46b ... Outlet buffer part 38a, 38b, 48a, 48b ... Emboss 42a ... Supply hole part 42b ... Discharge hole part 44 ... Oxidant gas flow path 54 ... Cooling medium flow path

Claims (2)

An electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of the electrolyte membrane and a separator are stacked, and a reaction gas flow path for supplying a reaction gas along the electrode surface is formed, and the reaction gas is stacked in the stacking direction. A fuel cell in which a reaction gas communication hole to be circulated is formed,
The separator is positioned on the inlet side of the reaction gas channel, and has a substantially triangular inlet buffer portion having a width dimension equivalent to that of the reaction gas channel;
A supply side of the reaction gas communication hole located on one ridge line side of the inlet buffer unit;
Is provided,
The inlet buffer portion has a plurality of convex portions, and the convex portions are arranged so that the arrangement density on the central portion side of the inlet buffer portion is sparse compared to the arrangement density on the end portion side of the inlet buffer portion. A fuel cell characterized by being set. 2. The fuel cell according to claim 1, wherein the separator is positioned on an outlet side of the reaction gas channel, and has a substantially triangular outlet buffer portion having a width dimension equivalent to that of the reaction gas channel;
Corresponding to the supply side of the reaction gas communication hole and the position of the point object, the discharge side of the reaction gas communication hole located on one ridge line side of the outlet buffer unit,
Is provided,
The outlet buffer portion has a plurality of convex portions, and the convex portions are arranged such that the arrangement density on the central portion side of the outlet buffer portion is sparse compared to the arrangement density on the end portion side of the outlet buffer portion. A fuel cell characterized by being set.

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