JP2012190634A - Fuel cell stack and seal formation method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mold a seal member in a separator for power generation cell and a separator for dummy cell by using the same injection molding die while reducing the manufacturing cost well.SOLUTION: The seal formation method of a fuel cell stack 10 includes a step for molding a terminal seal from the edge of a protrusion 58 of a cell voltage monitoring terminal provided in a second metal separator 30 configuring a power generation cell while circulating the inside, and a step for molding a dummy seal in a second metal separator 30D configuring a dummy cell, at a position corresponding to the protrusion 58, by the same mold apparatus 90 as the mold apparatus 90 molding the terminal seal.

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, and a stacked body in which a plurality of power generation cells for generating power are stacked, and both ends in the stacking direction of the stacked body The present invention relates to a fuel cell stack including a dummy cell that is disposed in a portion and corresponds to the power generation cell and that does not generate power, and a seal forming method thereof.

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

  In this type of fuel cell stack, in order to obtain a desired power generation performance, a predetermined number (for example, several tens to several hundreds) of power generation cells are stacked, and each power generation cell has a desired power generation performance. It is necessary to detect whether or not. For this reason, in general, a cell voltage monitoring terminal provided on the separator is connected to a voltage detection device (cell voltage monitor) to detect a cell voltage for each power generation cell during power generation. Yes.

  For example, the connector device disclosed in Patent Document 1 includes a cell-side connector 1 and a monitor-side connector 2 as shown in FIG. The cell-side connector 1 includes a cell-side terminal 3, a cell-side housing 4, and a seal rubber 5. The monitor-side connector 2 includes a monitor-side terminal 6, a monitor-side housing (not shown), and a seal rubber 7. The cell side connector 1 is connected to a cell of the fuel cell, while the monitor side connector 2 is connected to a measuring instrument that measures the cell voltage.

JP 2008-198429 A

  By the way, in the fuel cell stack, there is a power generation cell in which a temperature drop is likely to be caused as compared with other power generation cells due to heat radiation to the outside. In particular, the power generation cell arranged at the end in the stacking direction has a remarkable temperature drop. For this reason, dummy cells that do not contribute to power generation, for example, have gas flow paths but do not have MEAs, are disposed at both ends of the power generation cell stack.

  In this case, in the separator constituting the power generation cell, the seal rubber 5 constituting the cell side connector 1 is formed on the cell side terminal 3 by, for example, injection molding. On the other hand, the cell side connector 1 is not required in the separator constituting the dummy cell.

  Therefore, a mold for injection molding a seal member including the seal rubber 5 with respect to the separator constituting the normal power generation cell and a mold for injection molding the seal member with respect to the separator constituting the dummy cell are used separately. ing. As a result, there is a problem that the equipment cost increases so that it is not economical.

  The present invention solves this type of problem, and the sealing member can be molded using the same injection mold for the power cell separator and the dummy cell separator, resulting in good manufacturing costs. It is an object of the present invention to provide a fuel cell stack and a method for forming a seal thereof that can be reduced to a minimum.

  The present invention includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a metal separator, and a stacked body in which a plurality of power generation cells for generating power are stacked, and in the stacking direction of the stacked body The present invention relates to a fuel cell stack including dummy cells disposed at both ends and corresponding to the power generation cells and not generating power, and a method for forming a seal thereof.

  In this fuel cell stack, a power cell-side metal separator that constitutes a power generation cell is provided with a protrusion for a cell voltage monitoring terminal, and a terminal seal is provided around the tip edge of the protrusion. On the other hand, the dummy cell side metal separator constituting the dummy cell is provided with a dummy seal portion formed by the same die as the die for forming the terminal seal portion at a position corresponding to the protruding portion.

  Further, in this seal forming method, a step of forming the terminal seal portion around the tip edge of the protrusion of the cell voltage monitoring terminal provided on the power generation cell side metal separator constituting the power generation cell, and a dummy cell Forming a dummy seal portion with the same mold as the mold for molding the terminal seal portion at a position corresponding to the protruding portion.

  According to the present invention, using the same mold, the step of forming the terminal seal portion on the protrusion of the cell voltage monitoring terminal provided on the power generation cell side metal separator constituting the power generation cell, and the dummy cell constituting the dummy cell And forming a dummy seal portion on the side metal separator.

  Accordingly, it is not necessary to use dedicated molds for forming the sealing members on the power generation cell side metal separator and the dummy cell side metal separator. Thereby, the number of molds can be reduced, and the manufacturing cost can be reduced well.

1 is a schematic perspective view of a fuel cell stack according to an embodiment of the present invention. FIG. 4 is a partially omitted cross-sectional explanatory view of the fuel cell stack. It is a principal part schematic perspective view of the electric power generation unit which comprises the said fuel cell stack. It is a principal part schematic perspective view of the 1st dummy unit which comprises the said fuel cell stack. It is explanatory drawing of the voltage measurement terminal and connector which comprise the said fuel cell stack. It is principal part cross-sectional explanatory drawing of the metal mold | die apparatus for injection-molding a sealing member. It is explanatory drawing of the state by which the edge part of the 2nd metal separator which comprises a 1st dummy unit is arrange | positioned at the said metal mold apparatus. It is a section explanatory view of the connector device indicated by patent documents 1.

  As shown in FIGS. 1 and 2, the fuel cell stack 10 according to the embodiment of the present invention includes a stacked body 14 in which a plurality of power generation units (power generation cells) 12 are stacked in the arrow A direction. A first end power generation unit 16a and a first dummy unit 18a are disposed outward at one end in the stacking direction of the stacked body 14, and a second end portion is disposed at the other end in the stacking direction of the stacked body 14. The power generation unit 16b and the second dummy unit 18b are arranged outward. Terminal plates 20a and 20b, insulating plates 22a and 22b, and end plates 24a and 24b are disposed outward in the first and second dummy units 18a and 18b.

  The fuel cell stack 10 is integrally held by a box-like casing (not shown) including end plates 24a, 24b configured in a rectangular shape as end plates, or a plurality of fuel cell stacks 10 extending in the direction of arrow A, for example. It is clamped and held together by a tie rod (not shown).

  As shown in FIG. 3, the power generation unit 12 includes a first metal separator 26, a first electrolyte membrane / electrode structure 28a, a second metal separator (power generation cell side metal separator) 30, and a second electrolyte membrane / electrode structure 28b. And the third metal separator 32 in the order of the arrow A.

  In this embodiment, the power generation cell includes the first and second electrolyte membrane / electrode structures 28a and 28b, which are two electrolyte membrane / electrode structures, but three or more electrolyte membrane / electrode structures are provided. Or a power generation cell including one electrolyte membrane / electrode structure may be employed.

  The first metal separator 26, the second metal separator 30, and the third metal separator 32 have a rectangular shape, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a surface for corrosion protection on the metal surface. It is composed of a processed metal plate.

  The first to third metal separators 26, 30, and 32 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing the metal thin plate 34 into a wave shape. The first to third metal separators 26, 30, and 32 circulate around the outer periphery of the thin metal plate 34, and the seal member 35 is integrally formed.

  The upper end edge in the long side direction of the power generation unit 12 communicates with each other in the direction of arrow A, and an oxidant gas supply communication hole 36a for supplying an oxidant gas, for example, an oxygen-containing gas, and a fuel gas, for example, A fuel gas supply passage 38a for supplying a hydrogen-containing gas is provided.

  The lower end edge of the power generation unit 12 in the long side direction communicates with each other in the direction of the arrow A, the fuel gas discharge communication hole 38b for discharging the fuel gas, and the oxidant gas discharge for discharging the oxidant gas. A communication hole 36b is provided.

  A pair of cooling medium supply communication holes 40a for communicating with each other in the direction of arrow A and for supplying a cooling medium are provided at one end edge of the power generation unit 12 in the short side direction (arrow B direction). A pair of cooling medium discharge communication holes 40b for discharging the cooling medium is provided at the other end edge of the unit 12 in the short side direction.

  The first electrolyte membrane / electrode structure 28a and the second electrolyte membrane / electrode structure 28b include, for example, a solid polymer electrolyte membrane 42 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane 42. A cathode side electrode 44 and an anode side electrode 46 sandwiching the electrode.

  The cathode side electrode 44 and the anode side electrode 46 are uniformly coated on the surface of the gas diffusion layer 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. An electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 42.

  A first oxidant gas flow channel 48 communicating the oxidant gas supply communication hole 36a and the oxidant gas discharge communication hole 36b is formed on a surface 26a of the first metal separator 26 facing the first electrolyte membrane / electrode structure 28a. Is formed. The first oxidizing gas channel 48 has a plurality of channel grooves extending in the direction of arrow C. A cooling medium flow path 50 that connects the cooling medium supply communication hole 40 a and the cooling medium discharge communication hole 40 b is formed on the surface 26 b of the first metal separator 26.

  On the surface 30a of the second metal separator 30 that faces the first electrolyte membrane / electrode structure 28a, a first fuel gas flow path 52 that connects the fuel gas supply communication hole 38a and the fuel gas discharge communication hole 38b is formed. The The first fuel gas channel 52 has a plurality of channel grooves extending in the direction of arrow C.

  A second oxidant gas flow channel 54 communicating the oxidant gas supply communication hole 36a and the oxidant gas discharge communication hole 36b is formed on the surface 30b of the second metal separator 30 facing the second electrolyte membrane / electrode structure 28b. Is formed.

  A second fuel gas flow path 56 that connects the fuel gas supply communication hole 38a and the fuel gas discharge communication hole 38b is formed on the surface 32a of the third metal separator 32 that faces the second electrolyte membrane / electrode structure 28b. The A cooling medium flow path 50 that connects the cooling medium supply communication hole 40 a and the cooling medium discharge communication hole 40 b is formed on the surface 32 b of the third metal separator 32.

  The second metal separator 30 is provided with a protrusion 58 of a cell voltage monitoring terminal that is located between the pair of cooling medium discharge communication holes 40b and protrudes outward at the center of one long side. The protrusion 58 may be provided on the first metal separator 26 or the third metal separator 32.

  The protrusions 58 are integrally formed so as to protrude from the outer periphery of the long side or the short side of the thin metal plate 34 constituting the second metal separator 30. A terminal seal portion 35a is provided around the inner edge from the tip edge of the protrusion 58. The terminal seal portion 35 a is integrally formed with the seal member 35.

  As shown in FIG. 2, the first end power generation unit 16a includes, from the power generation unit 12 side, the first metal separator 26, the first electrolyte membrane / electrode structure 28a, the second metal separator 30, the conductive plate (dummy electrolyte / Electrode structure) 60 and third metal separator 32 are laminated in this order. The first end power generation unit 16a is substantially a mixed unit of a part of the power generation unit 12 and a part of the first dummy unit 18a.

  In the first end power generation unit 16a, the heat insulating layer 61a is formed by corresponding to the second fuel gas passage 56 and regulating the flow of the fuel gas. Specifically, the second fuel gas passage 56 is closed from the fuel gas supply communication hole 38a and the fuel gas discharge communication hole 38b.

  A heat insulating layer 61b is formed between the first end power generation unit 16a and the first dummy unit 18a by corresponding to the cooling medium flow path 50 and restricting the flow of the cooling medium. Specifically, the cooling medium flow path 50 is closed from the cooling medium supply communication hole 40a and the cooling medium discharge communication hole 40b.

  As shown in FIG. 4, the first dummy unit 18a includes a first metal separator 26, a first conductive plate (first dummy electrolyte / electrode structure) 62a, and a second metal separator from the first end power generation unit 16a side. (Dummy cell side metal separator) 30D, the second conductive plate (second dummy electrolyte / electrode structure) 62b, and the third metal separator 32 are laminated in this order.

  The first metal separator 26, the second metal separator 30D and the third metal separator 32 of the first dummy unit 18a are the same as the first metal separator 26, the second metal separator 30 and the third metal separator 32 of the power generation unit 12. . The first conductive plate 62a and the second conductive plate 62b may use the first electrolyte membrane / electrode structure 28a and the second electrolyte membrane / electrode structure 28b of the power generation unit 12.

  The conductive plate 60, the first conductive plate 62a, and the second conductive plate 62b are set, for example, to the same thickness as the first electrolyte membrane / electrode structure 28a and do not have a power generation function.

  The second metal separator 30D is provided with a dummy seal portion 35b that is located between the pair of cooling medium discharge communication holes 40b and protrudes outward at the center of one long side. As will be described later, the dummy seal portion 35b is formed by the same mold as the terminal seal portion 35a.

  In the first dummy unit 18a, the first oxidant gas channel 48 and the oxidant gas are used to restrict the oxidant gas from flowing through the first oxidant gas channel 48 and the second oxidant gas channel 54. The supply communication hole 36a and the oxidant gas discharge communication hole 36b are closed via the blocking portions 64a and 64b, while the second oxidant gas flow path 54, the oxidant gas supply communication hole 36a, and the oxidant. The gas discharge communication hole 36b is closed through the blocking portions 64a and 64b.

  In the first dummy unit 18 a, the fuel gas flows along the first fuel gas flow path 52 and the second fuel gas flow path 56, and the cooling medium flows along the cooling medium flow path 50.

  The second end power generation unit 16b is configured similarly to the first end power generation unit 16a, while the second dummy unit 18b is configured similar to the first dummy unit 18a.

  As shown in FIG. 1, at the upper and lower end edges of the end plate 24a, an oxidant gas inlet manifold 66a that communicates with the oxidant gas supply communication hole 36a, a fuel gas inlet manifold 68a that communicates with the fuel gas supply communication hole 38a, An oxidant gas outlet manifold 66b that communicates with the oxidant gas discharge communication hole 36b and a fuel gas outlet manifold 68b that communicates with the fuel gas discharge communication hole 38b are provided at both upper and lower edges.

  Although not shown, a fuel gas supply device and an oxidant gas supply device are coupled to the end plate 24a side. The fuel gas outlet manifold 68b communicates with the fuel gas inlet manifold 68a via a return flow path (not shown) so that the fuel gas circulates and can be reused. This is to prevent wasteful disposal of hydrogen as the fuel gas.

  A cooling medium inlet manifold 70a that communicates with the cooling medium supply communication hole 40a and a cooling medium outlet manifold 70b that communicates with the cooling medium discharge communication hole 40b are provided at both left and right edges of the end plate 24b.

  As shown in FIG. 5, a connector 72 is connected to the protrusion 58 of the cell voltage monitoring terminal provided on the second metal separator 30, and the connector 72 is connected to a voltage measuring device (via a cable 74). ECU) 76 (see FIG. 1).

  As shown in FIG. 5, the connector 72 has a U-shaped connection terminal portion 77 connected to the protrusion 58 of the cell voltage monitoring terminal. A resin casing member 80 is disposed so as to cover the connection portion 78 between the protrusion 58 and the connection terminal portion 77. The casing member 80 includes a first member 82 that holds the protruding portion 58 and a second member 84 that holds the connector 72. An annular seal member 88 is provided on the outer peripheral portion of the cylindrical portion 86 provided in the casing member 80.

  FIG. 6 is a partial cross-sectional view of an injection mold apparatus 90 for integrally molding the seal member 35 on the second metal separators 30 and 30D.

  The mold apparatus 90 includes a first mold 92 and a second mold 94, and a cavity 96 is formed between the first mold 92 and the second mold 94. On the inner surface of the first mold 92 and the inner surface of the second mold 94, pressers 98a and 98b are formed for sandwiching the protrusions 58 of the cell voltage monitoring terminal formed integrally with the second metal separator 30.

  The second metal separator 30D is not provided with the protrusion 58, or the end 30De of the second metal separator 30D shorter than the protrusion 58 is terminated in the cavity 96 (see 2 in FIG. 6). (See dotted line). As shown in FIG. 7, the second electrolyte membrane / electrode structure 28b is not exposed to the metal portion, and is entirely covered with the dummy seal portion 35b.

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

  First, as shown in FIG. 1, in the fuel cell stack 10, in the end plate 24a, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet manifold 66a and a hydrogen-containing gas is supplied to the fuel gas inlet manifold 68a. Etc. are supplied. Further, in the end plate 24b, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet manifold 70a.

  As shown in FIG. 3, the oxidant gas is supplied from the oxidant gas supply communication hole 36 a constituting each power generation unit 12 to the second oxidant gas channel 48 of the first metal separator 26 and the second oxidant gas flow path of the second metal separator 30. It is introduced into the oxidant gas channel 54. For this reason, the oxidizing gas moves vertically downward along the cathode side electrodes 44 of the first and second electrolyte membrane / electrode structures 28a, 28b.

  On the other hand, the fuel gas is introduced into the first fuel gas flow path 52 of the second metal separator 30 and the second fuel gas flow path 56 of the third metal separator 32 from the fuel gas supply communication hole 38a constituting each power generation unit 12. The Therefore, the fuel gas moves vertically downward along the anode-side electrodes 46 of the first and second electrolyte membrane / electrode structures 28a, 28b.

  As described above, in the first and second electrolyte membrane / electrode structures 28a and 28b, the oxidant gas supplied to each cathode side electrode 44 and the fuel gas supplied to each anode side electrode 46 are electrodes. It is consumed by an electrochemical reaction in the catalyst layer and power is generated.

  Next, the oxidant gas supplied to and consumed by the cathode side electrode 44 is discharged from the oxidant gas discharge communication hole 36b to the oxidant gas outlet manifold 66b (see FIG. 1). Similarly, the fuel gas supplied to and consumed by the anode side electrode 46 is discharged from the fuel gas discharge communication hole 38b to the fuel gas outlet manifold 68b.

  Further, the cooling medium is introduced into the cooling medium flow path 50 formed between the power generation units 12 as shown in FIGS. 2 and 3. The cooling medium flows along the arrow B direction (horizontal direction in FIG. 3), and the second electrolyte membrane / electrode structure 28b of one power generation unit 12 and the first electrolyte membrane / electrode structure of the other power generation unit 12 are arranged. The body 28a is cooled. That is, the cooling medium does not cool between the first and second electrolyte membrane / electrode structures 28a and 28b in the power generation unit 12, that is, after so-called thinning cooling, the cooling medium discharge communication hole 40b to the cooling medium outlet manifold 70b. Discharged.

  In this case, in this embodiment, when the sealing member 35 is injection-molded on the metal separator 30 constituting the power generation unit 12, the metal thin plate 34 constituting the second metal separator 30 is used as a mold device as shown in FIG. 90.

  In the mold apparatus 90, the pressing parts 98 a and 98 b of the first mold 92 and the second mold 94 are clamped in a state where the protrusions 58 provided on the metal thin plate 34 are sandwiched. Then, for example, silicone rubber is injected into the cavity 96, so that the seal member 35 is injection-molded so as to cover the metal thin plate 34.

  At that time, the protrusion 58 protrudes outward from the outer peripheral surface of the metal thin plate 34 by a predetermined length and is circulated around the seal member 35. As a result, the seal member 35 is integrally formed with the second metal separator 30 that is the power generation cell side metal separator.

  Next, a metal thin plate 34 for manufacturing the second metal separator 30D constituting the first dummy unit 18a is disposed in the mold apparatus 90. The thin metal plate 34 is not provided with the protruding portion 58 (or shorter than the protruding portion 58), and terminates at a position spaced inward from the end face of the cavity 96.

  In this state, for example, silicone rubber is injected into the cavity 96, so that the seal member 35 is integrally formed around the outer periphery of the thin metal plate 34. Accordingly, the seal member 35 is integrally formed with the second metal separator 30D that is the dummy cell side metal separator.

  Here, the second metal separator 30D has a dummy at a position corresponding to the protrusion 58 of the cell voltage monitoring terminal of the second metal separator 30, that is, without exposing the metal portion around the entire periphery of the end 30De. The seal part 35b is molded. For this reason, using the same mold apparatus 90, the terminal seal portion 35a is formed on the protrusion 58 provided on the second metal separator 30 that is the power generation cell side metal separator, and the second cell that is the dummy cell side metal separator. A dummy seal portion 35b is formed on the metal separator 30D.

  Therefore, it is not necessary to use a dedicated mold device for molding the sealing member 35 on the second metal separator 30 and the second metal separator 30D. Thereby, it can respond by the single metal mold | die apparatus 90, it becomes possible to reduce the number of metal mold | dies, and the effect that a manufacturing cost is reduced favorably is acquired.

  In addition, since there is no need for a dedicated mold device for each, there is an advantage that the space can be narrowed, the wrong assembly of the mold is prevented, and the molding yield can be easily improved.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Electric power generation unit 14 ... Laminated body 16a, 16b ... End part electric power generation unit 18a, 18b ... Dummy unit 26, 30, 30D, 32 ... Metal separator 28a, 28b ... Electrolyte membrane and electrode structure 35 ... Seal Member 35a ... Terminal seal part 35b ... Dummy seal part 42 ... Solid polymer electrolyte membrane 44 ... Cathode side electrode 46 ... Anode side electrodes 48, 54 ... Oxidant gas flow path 50 ... Coolant flow path 52, 56 ... Fuel gas flow Path 58... Projection 60, 62 a, 62 b... Conductive plates 61 a and 61 b... Heat insulation layer 66 a. ... Mold device 92 ... First mold 94 ... Second mold 96 ... Cavity

Claims (2)

A laminate in which a plurality of power generation cells for generating power are stacked, each of which includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of the electrolyte, and a metal separator;
Dummy cells that are disposed at both ends in the stacking direction of the stacked body and correspond to the power generation cells and do not generate power;
A fuel cell stack comprising:
The power generation cell side metal separator constituting the power generation cell is provided with a protrusion of a cell voltage monitoring terminal, and a terminal seal portion is provided around the inner edge from the front edge of the protrusion,
The dummy cell-side metal separator constituting the dummy cell is provided with a dummy seal portion formed of the same mold as the mold for molding the terminal seal portion at a position corresponding to the protrusion. Battery stack. A laminate in which a plurality of power generation cells for generating power are stacked, each of which includes an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of the electrolyte, and a metal separator;
Dummy cells that are disposed at both ends in the stacking direction of the stacked body and correspond to the power generation cells and do not generate power;
A fuel cell stack seal forming method comprising:
Forming a terminal seal part by circling inwardly from the leading edge of the protrusion of the cell voltage monitoring terminal provided on the power generation cell side metal separator constituting the power generation cell;
Forming a dummy seal portion with the same mold as the mold for molding the terminal seal portion at a position corresponding to the protrusion on the dummy cell side metal separator constituting the dummy cell;
A method for forming a seal of a fuel cell stack, comprising:

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