JP4417135B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is sandwiched between a pair of metal separators.

  For example, a polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane. A fuel cell is configured by sandwiching an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of the electrolyte membrane with a separator. Each of the anode side electrode and the cathode side electrode has a noble metal-based electrode catalyst layer bonded to a base material mainly composed of carbon.

  In this fuel cell, a fuel gas, for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is supplied to the anode side electrode, while an oxidant gas, for example, A gas or air mainly containing oxygen (hereinafter also referred to as oxygen-containing gas) is supplied. In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  By the way, although the separator is usually made of a carbon-based material, it has been pointed out that the carbon-based material cannot be thinned due to factors such as strength. Therefore, recently, a separator made of a thin metal plate (hereinafter also referred to as a metal separator), which is superior in strength to this type of carbon separator and can be easily thinned, is subjected to press working on the metal separator to obtain a desired reaction gas. By shaping the flow path, a contrivance has been made to reduce the thickness of the metal separator to reduce the size and weight of the entire fuel cell.

  In this case, the metal separator is provided with a resin seal that performs electrical insulation and has a sealing function. For example, in the manufacturing method disclosed in Patent Document 1, as shown in FIG. 9, the metal thin plate 3 is formed on the mating surface of the fixed mold plate 2a and the movable mold plate 2b constituting the injection mold 1. Is retained. In the mold cavity, a resin flow path 4 is formed at the peripheral edge portion of the thin metal plate 3 via the cross-sectional portion 3a.

  Then, by injecting the liquid silicone resin 6 from the gate 5 of the metal thin plate 3 into the mold cavity, a silicone resin layer 7 is formed on both surfaces of the metal thin plate 3 so as to cover the peripheral edge.

JP-A-11-309746 (FIG. 1)

  By the way, the fuel cell normally forms a stack by stacking several tens to several hundreds of single cells. At that time, it is necessary to accurately position each single cell, and for this reason, an operation of inserting a knock pin into a positioning hole formed in the single cell is performed. However, as the number of stacked single cells increases, the operation of inserting the knock pin becomes difficult, the workability is lowered, the position of the member is easily displaced, and the sealing function is lowered.

  Therefore, if positioning of the unit cell is performed using the outer periphery of the unit cell, for example, two adjacent sides, a knock pin can be eliminated, and workability can be improved. However, in said patent document 1, the silicone resin layer 7 is formed covering the outer peripheral part of the metal thin plate 3, and there exists a problem that this silicone resin layer 7 cannot be used as a positioning reference. This is because the silicone resin layer 7 is easily deformed and the outer peripheral position of the unit cell cannot be set accurately.

  The present invention solves this kind of problem, and aims to provide a fuel cell capable of performing accurate positioning through the outer periphery of a metal separator and improving the formability of a coating member. To do.

  The present invention is a fuel cell in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is sandwiched between a pair of metal separators, the metal separators covering the outer peripheral edge of the metal plate Is integrally molded. At least one metal exposed portion having a positioning function when the fuel cell is assembled is provided on the outer periphery of the metal plate so as to be exposed to the outside from the covering member.

  Moreover, it is preferable that the edge part of the coating | coated member which surrounds a metal exposure part is set to the obtuse angle | corner which protrudes outside.

  Furthermore, the metal exposed portion is preferably provided on two adjacent sides of the metal plate.

  Furthermore, the pair of metal separators is preferably provided with a metal exposed portion at the same position on the outer periphery thereof. For this reason, positioning of a pair of metal separators is performed correctly.

  According to the present invention, the metal exposed portion is provided on the outer periphery of the metal plate so as to be exposed to the outside, and the positioning accuracy during assembly of the fuel cell is improved satisfactorily through the metal exposed portion.

  And since the edge part which protrudes outside the edge part of a coating | coated member is set to an obtuse angle, the intensity | strength of the said corner part improves. Therefore, it is possible to effectively prevent the corners from being damaged during the formation and improve the moldability.

  Furthermore, even if burrs are generated at the corners, the necessary parts when peeling the burrs are peeled together, such as right-angled corners or acute corners, and the corners are chipped. There is nothing. Thereby, while improving the insulation quality of a coating | coated member, it becomes possible to obtain a metal separator efficiently.

  FIG. 1 is a schematic exploded perspective view of a fuel cell 10 according to an embodiment of the present invention.

  The fuel cell 10 includes an electrolyte membrane (electrolyte) / electrode structure 12, and first and second metal separators 14 and 16 that sandwich the electrolyte membrane / electrode structure 12. The fuel cell 10 may be configured as a single unit or may be stacked to form a fuel cell stack 60 (described later).

  One end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, which is the stacking direction, and an oxidant gas supply communication hole 20a for supplying an oxidant gas, for example, an oxygen-containing gas. A cooling medium discharge communication hole 22b for discharging the medium and a fuel gas discharge communication hole 24b for discharging a fuel gas, for example, a hydrogen-containing gas, are arranged in the direction of arrow C (vertical direction).

  The other end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas supply communication hole 24a for supplying fuel gas, and a cooling medium supply communication hole for supplying a cooling medium. 22a and an oxidant gas discharge communication hole 20b for discharging the oxidant gas are arranged in the direction of arrow C.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 26 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 28 and a cathode side provided on both surfaces of the solid polymer electrolyte membrane 26. An electrode 30.

  The anode side electrode 28 and the cathode side electrode 30 include a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles having a platinum alloy supported on the surface are uniformly applied to the surface of the gas diffusion layer. Respectively. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 26.

  As shown in FIG. 2, on the surface 14a of the first metal separator 14 facing the electrolyte membrane / electrode structure 12, there is a fuel gas passage 32 communicating with the fuel gas supply communication hole 24a and the fuel gas discharge communication hole 24b. It is formed. The fuel gas channel 32 includes, for example, a plurality of grooves extending linearly in the arrow B direction.

  As shown in FIG. 1, between the surface 14b opposite to the surface 14a of the first metal separator 14 and the surface 16b of the second metal separator 16, there are a cooling medium supply communication hole 22a and a cooling medium discharge communication hole 22b. A cooling medium flow path 34 communicating with is formed. The cooling medium flow path 34 is constituted by, for example, a plurality of straight flow path grooves extending in the arrow B direction.

  The surface 16a of the second metal separator 16 facing the electrolyte membrane / electrode structure 12 is provided with an oxidant gas flow path 36 communicating with the oxidant gas supply communication hole 20a and the oxidant gas discharge communication hole 20b. The oxidant gas flow path 36 includes, for example, a plurality of grooves extending linearly in the arrow B direction.

  As shown in FIG. 2, the first metal separator 14 includes a metal plate 40 that is pressed into a corrugated shape, and the outer periphery of the metal plate 40 is provided on both surfaces of the metal plate 40, that is, the surfaces 14 a and 14 b. A resin-made first seal member (covering member) 42 is integrally formed by injection molding or the like.

  The metal plate 40 is, for example, a thin plate-like metal plate having a thickness of 0.05 mm to 1.0 mm, such as a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, a metal thin plate having a surface subjected to anticorrosion treatment, or the like. Used and formed into a desired shape by press molding. The first seal member 42 uses, for example, a seal material such as EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do.

  The first seal member 42 covers the fuel gas supply communication hole 24a, the fuel gas discharge communication hole 24b, and the fuel gas passage 32 on the surface 14a to prevent fuel gas from leaking (see FIG. 2). The cooling medium supply communication hole 22a, the cooling medium discharge communication hole 22b, and the cooling medium flow path 34 are covered to prevent leakage of the cooling medium (see FIG. 1).

  On the outer periphery of the first metal separator 14, two adjacent sides 44a and 44b, that is, a side 44a that is long in the direction of arrow B (horizontal direction) and a side 44b that is short in the direction of arrow C (vertical direction) In addition, two exposed metal portions 46 a and 46 b and one exposed metal portion 46 c are respectively exposed from the first seal member 42 to the outside. The first seal member 42 is provided with a corner portion 48a projecting to the outside at an end portion surrounding the metal exposed portion 46a, and the corner portion 48a is set to an obtuse angle θ ° (θ °> 90 °).

  An end portion that surrounds the metal exposed portion 46b of the first seal member 42 is provided with a corner portion 48b that protrudes to the outside, and the corner portion 48b is set to an obtuse angle θ °. Similarly, a corner portion 48c that protrudes to the outside is provided at an end portion surrounding the metal exposed portion 46c of the first seal member 42, and the corner portion 48c is set to an obtuse angle θ °.

  As shown in FIG. 1, the second metal separator 16 circulates around the outer peripheral edge of a metal plate 50 that has been pressed into a wave shape, and a second seal member (covering member) 52 made of resin is formed by injection molding or the like. It is integrally molded. The second seal member 52 covers the oxidant gas supply communication hole 20a, the oxidant gas discharge communication hole 20b, and the oxidant gas flow path 36 on the surface 16a to prevent leakage of oxidant gas, while on the surface 16b, The cooling medium supply communication hole 22a, the cooling medium discharge communication hole 22b, and the cooling medium flow path 34 are covered to prevent leakage of the cooling medium.

  On the outer periphery of the metal plate 50, two metal exposed portions 56a and 56b and one metal exposed portion 56c are exposed to the outside from the second seal member 52 on two adjacent sides 54a and 54b, respectively. Provided. In the second seal member 52, corner portions 58a to 58c projecting to the outside are provided at end portions surrounding the metal exposed portions 56a to 56c, and the corner portions 58a to 58c are respectively set to an obtuse angle θ °. .

  FIG. 3 is a schematic perspective view of an assembling apparatus 80 for assembling the fuel cell stack 60 by stacking a plurality of fuel cells 10, and FIG. 4 is a side view of the assembling apparatus 80.

  The assembling apparatus 80 includes a frame member 82. The frame member 82 includes fixing plates 84a and 84b disposed at both ends of the arrow A direction, four parallel guide bars 86 disposed at the four corners of the fixing plates 84a and 84b and extending in the arrow A direction, An intermediate fixing plate 84c supported by the guide bar 86 and disposed between the fixing plates 84a and 84b. The intermediate fixing plate 84c is close to the fixing plate 84b.

  A pair of pulleys 90 is attached to one fixing plate 84a constituting the frame member 82 via a block 88a. A pair of support rod portions 92 are fixed to a lower portion of the other fixing plate 84b constituting the frame member 82 via a block 88b so that the height can be adjusted.

  The pulley unit 90 is held by the stopper 94 and disposed on the horizontal floor surface F, while the support rod unit 92 is disposed on the horizontal floor surface F. In general, the frame member 82 has a tip end in the arrow A1 direction (fixed plate 84a side) inclined downward from a tip end in the arrow A2 direction (fixed plate 84b side).

  The frame member 82 includes at least a stacking part including the unitized fuel cells 10 stacked in the direction of the arrow A2 from the pulley unit 90 side to obtain the fuel cell stack 60, and the fuel cell stack 60. And a pressurizing unit 98 for applying a pressing force in the direction of the arrow A1.

  As shown in FIG. 5, the mounting portion 96 includes first and second positioning portions 102 and 104 that position and support a laminated component, for example, a unitized fuel cell 10. The fuel cell 10 is provided with exposed metal portions 46a, 46b, 56a and 56b on one long side (sides 44a and 54a), and provided with exposed metal portions 46c and 56c on one short side (sides 44b and 54b). It is done. The first positioning portion 102 is provided with lower support rods 106a and 106b that are parallel to each other in the arrow A direction and have different heights (arrow C direction), while the second positioning portion 104 extends in the arrow A direction. Side support rods 108 are provided. The lower support rod 106a supports the metal exposed portions 46a and 56a, the lower support rod 106b supports the metal exposed portions 46b and 56b, and the side support rod 108 supports the metal exposed portions 46c and 56c.

  As shown in FIGS. 3 and 4, the pressurizing unit 98 includes a cylinder 110 that is fixed to a fixing plate 84 b that constitutes the frame member 82. A pressing portion 114 is connected to the tip of the rod 112 protruding from the cylinder 110 in the arrow A1 direction, and the pressing portion 114 engages with the pressing plate 116.

  The pressing plate 116 is supported by the four guide bars 86 and can advance and retreat in the direction of arrow A. At both ends of the pressing plate 116 in the longitudinal direction (arrow B direction), handle portions 120 that can be gripped by the operator are provided.

  As shown in FIG. 4, on the horizontal floor surface F, an elevating unit 122 that engages with the lower part of the frame member 82 and swings the frame member 82 in the direction of arrow G at a position close to the pulley unit 90 side. Is placed. The elevating part 122 is constituted by, for example, a jack or the like, and the fuel cell stack 60 can be disposed in a horizontal posture by swinging upward in the stacking direction upstream of the fuel cell stack 60. The elevating unit 122 can employ various actuators that can be operated manually or automatically.

  An operation for manufacturing the fuel cell 10 configured as described above will be described below.

  As shown in FIGS. 6 and 7, an injection mold 130 that covers the outer peripheral edge portions of the metal plates 40 and 50 and integrates the first and second seal members 42 and 52 is a mold member 132 that can be opened and closed with respect to each other. , 134. With the mold members 132 and 134 closed, a cavity 136 corresponding to the shape of the first and second seal members 42 and 52 is formed. For example, the mold members 132 and 134 are provided with bulging portions 138 and 140 corresponding to the shapes of the metal exposed portions 46a and 56a (see FIG. 7).

  Therefore, for example, the resin material is filled in the cavity 136 in a state where the metal plate 40 is disposed between the mold members 132 and 134 and the mold is clamped. Therefore, the first seal member 42 is formed so as to cover the outer peripheral edge portion of the metal plate 40, and metal exposed portions 46a, 46b and 46c are provided at predetermined portions via the bulging portions 138, 140. The first metal separator 14 is manufactured.

  In this case, in this embodiment, as shown in FIG. 2, an end portion that surrounds the metal exposed portion 46 a of the first seal member 42 is provided with a corner portion 48 that protrudes to the outside, and the corner portion 48 a The obtuse angle θ ° is set. Therefore, when the first metal separator 14 is released from the injection mold 130, it is possible to effectively prevent breakage or the like in the vicinity of the corner portion 48a and to improve moldability. An effect is obtained.

  Moreover, even if burrs or the like are generated at the corners 48a, portions necessary for peeling the burrs are not peeled together. Thereby, it is possible to satisfactorily prevent the corner portion 48 from being chipped.

  For example, as shown in FIG. 8, when a corner 48 aa set at a right angle is provided at an end surrounding the metal exposed portion 46 a of the first seal member 42, the mold is released from the injection mold 130. At this time, a chipped ka is likely to occur in the corner portion 48aa. In addition, when the finishing process is performed, breakage or the like is likely to occur in the right-angled corners 48aa, and it is difficult to guarantee the insulation quality.

  Therefore, in this embodiment, it is only necessary to set the corner portion 48a to an obtuse angle θ °, the moldability can be improved with a simple configuration, the insulation quality of the first seal member 42 is improved, and the first It becomes possible to obtain the metal separator 14 efficiently. Furthermore, when the first seal member 42 is injection-molded, the metal exposed portions 46a to 46c can be formed, and workability is improved at a stroke. In the second metal separator 16, the same effect as the first metal separator 14 can be obtained.

  Next, the operation of assembling the fuel cell stack 60 using the assembling apparatus 80 will be described below.

  First, in the fuel cell 10, the first and second metal separators 14 and 16 are disposed with the electrolyte membrane / electrode structure 12 interposed therebetween, and the fuel cell 10 is assembled by being fixed integrally with a fixture (not shown). It is done. Further, the fuel cell stack 60 is assembled by stacking a plurality of the fuel cells 10 via the assembly device 80.

  Specifically, as shown in FIG. 4, the frame member 82 constituting the assembling apparatus 80 is inclined with respect to the horizontal direction by arranging the pulley portion 90 and the support rod portion 92 on the horizontal floor surface F. is doing. Therefore, the end plate 150a, the insulating plate 152a, and the terminal plate 154a are sequentially arranged on the mounting portion 96 of the frame member 82 from the fixed plate 84a side. Further, the plurality of fuel cells 10 are disposed on the mounting portion 96 so as to be stacked on the terminal plate 154a.

  In this case, in the fuel cell 10, as shown in FIG. 1, the metal exposed portions 46 a and 56 a are provided on one long side (sides 44 a and 54 a) at a position overlapping with the arrow A direction, and the metal exposed portions 46 b and 56 b. Is also provided at a position overlapping in the direction of arrow A. Further, on one short side (sides 44 b and 54 b) of the fuel cell 10, metal exposed portions 46 c and 56 c are provided at positions that overlap in the arrow A direction.

  Therefore, as shown in FIG. 5, in each fuel cell 10, the metal exposed portions 46a and 56a are directly supported by the lower support rod 106a, and the metal exposed portions 46b and 56b are directly supported by the lower support rod 106b. Further, the exposed metal portions 46c and 56c are directly supported by the side support rods 108. Accordingly, the fuel cell 10 can be positioned and supported more accurately and reliably than when the outer peripheral portions of the first and second seal members 42 and 52 are supported by the first and second positioning portions 102 and 104.

  Thereby, in this embodiment, the fuel cells 10 are accurately positioned with respect to each other only by sequentially stacking the fuel cells 10 on the mounting portion 96, and the stacking operation of the fuel cells 10 can be performed with high accuracy. The effect of being executed quickly is obtained.

  Next, after a predetermined number of fuel cells 10 are stacked on the mounting portion 96, a terminal plate 154b, an insulating plate 152b, and an end plate 150b are stacked as shown in FIG. And the cylinder 110 which comprises the pressurization part 98 is driven, and the press part 114 is extruded through the rod 112 in the arrow A1 direction. Accordingly, the pressing unit 114 presses the pressing plate 116 in the direction of the arrow A1, and a predetermined pressing force is applied to the fuel cell stack 60 mounted on the mounting unit 96 along the stacking direction.

  Furthermore, the fuel cell stack 60 is tightened via a tightening rod or the like (not shown), and a predetermined tightening load is applied between the end plates 150a and 150b. Instead of the tightening rod, a configuration in which the entire fuel cell stack 60 is fixed by a casing (not shown) may be employed.

  After the fuel cell stack 60 is assembled, the elevating part 122 is driven and the frame member 82 is swung in the direction of arrow G in FIG. Thereby, the fuel cell stack 60 is arranged in a horizontal posture, and the fuel cell stack 60 can be easily taken out from the frame member 82.

  Next, the operation of the fuel cell 10 will be described.

  As shown in FIG. 1, the fuel cell 10 is supplied with an oxidant gas that is an oxygen-containing gas such as air, a fuel gas such as a hydrogen-containing gas, and a cooling medium such as pure water, ethylene glycol, or oil. For this reason, the oxidant gas is introduced from the oxidant gas supply communication hole 20 a into the oxidant gas flow path 36 of the second metal separator 16, and the oxidant gas constitutes the cathode side electrode 30 constituting the electrolyte membrane / electrode structure 12. Move along.

  Further, the fuel gas is introduced into the fuel gas flow path 32 of the first metal separator 14 from the fuel gas supply communication hole 24 a and moves along the anode side electrode 28 constituting the electrolyte membrane / electrode structure 12. Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode side electrode 30 and the fuel gas supplied to the anode side electrode 28 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  The oxidant gas consumed by being supplied to the cathode side electrode 30 is discharged in the direction of arrow A along the oxidant gas discharge communication hole 20b. Similarly, the fuel gas supplied to and consumed by the anode side electrode 28 is discharged in the direction of arrow A along the fuel gas discharge communication hole 24b.

  Further, the cooling medium supplied to the cooling medium supply communication hole 22a is introduced into the cooling medium flow path 34 between the first and second metal separators 14 and 16, and then flows along the arrow B direction. The cooling medium is discharged from the cooling medium discharge communication hole 22b after the electrolyte membrane / electrode structure 12 is cooled.

1 is a schematic exploded perspective view of a fuel cell according to an embodiment of the present invention. It is a front view of the 1st metal separator which comprises the said fuel cell. It is a schematic perspective view of an assembling apparatus for assembling a fuel cell stack. It is a side view of the said assembly apparatus. It is a front view of the said assembly apparatus. FIG. 5 is a cross-sectional view taken along the line VI-VI in FIG. 2 of an injection mold for injection molding a seal member on the metal separator. It is the VII-VII sectional view taken on the line of the said injection mold in FIG. It is explanatory drawing of the sealing member which has a right-angled corner | angular part. It is a partial cross section explanatory drawing of the conventional injection mold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Electrolyte membrane and electrode structure 14, 16 ... Metal separator 26 ... Solid polymer electrolyte membrane 28 ... Anode side electrode 30 ... Cathode side electrode 32 ... Fuel gas flow path 34 ... Cooling medium flow path 36 ... Oxidation Agent gas flow path 40, 50 ... Metal plates 42, 52 ... Seal members 46a-46c, 56a-56c ... Metal exposed portions 48a-48c, 58a-58c ... Corner 60 ... Fuel cell stack 80 ... Assembly device 82 ... Frame member 96 ... Placement part 98 ... Pressurization part 130 ... Injection mold

Claims (4)

A fuel cell in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is sandwiched between a pair of metal separators,
The pair of metal separators are integrally formed with a covering member covering the outer peripheral edge of the metal plate,
The fuel cell portion of the outer periphery of the metal plate, as at least one metal exposure portion having a positioning function during assembly of the fuel cell, which is characterized that you exposed outside from the cover member.   2. The fuel cell according to claim 1, wherein an end portion of the covering member surrounding the exposed metal portion is set to have an obtuse angle at a corner portion protruding outward. 3.   3. The fuel cell according to claim 1, wherein the metal exposed portion is provided on two adjacent sides of the metal plate.   4. The fuel cell according to claim 1, wherein the pair of metal separators are provided with the exposed metal portion at the same position on the outer periphery thereof. 5.

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