JP4865238B2 - Fuel cell stack - Google Patents

Description

  The present invention relates to a fuel cell stack in which a stacked body in which a plurality of electrolyte / electrode structures each having a pair of electrodes provided on both sides of an electrolyte and a plurality of separators are stacked is housed in a box-shaped casing.

  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.

  Normally, this fuel cell is used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) is stacked in order to obtain a desired power generation. In this fuel cell stack, the stacked fuel cells need to be reliably pressurized and held in order to prevent an increase in the internal resistance of the fuel cell and a decrease in the sealing performance of the reaction gas.

  Therefore, for example, a fuel cell stack of Patent Document 1 is known. As shown in FIG. 8, the fuel cell stack includes a stacked body 2 in which a plurality of unit cells 1 are stacked, and auxiliary plates 4a with end plates 3 and 3 interposed at both ends in the stacking direction of the stacked body 2. 4b are arranged.

  A pair of fastening bands 5 and 5 are disposed along both side portions of the laminate 2. Cylindrical connecting portions 6 are provided at the ends of the fastening bands 5 and 5 and the auxiliary plates 4a and 4b so that the respective holes are aligned in a straight line. The fastening bands 5 and 5 and the auxiliary plates 4a and 4b are integrally connected by inserting the metal pin 7 into each connecting portion 6.

  A plurality of bolts 8 are screwed onto the auxiliary plate 4a, while a plurality of disc springs 9 are disposed on the auxiliary plate 4b. Therefore, when the bolt 8 is screwed in, the end plate 3 is pressed downward, and the disc spring 9 disposed on the auxiliary plate 4b is compressed, which is necessary for the laminated body 2 via the pair of end plates 3. The fastening pressure is applied.

JP 2001-135344 A (FIG. 5)

  However, in Patent Document 1 described above, a plurality of bolts 8 and a plurality of disc springs 9, which are dedicated parts, are provided in order to adjust the tightening load of the fuel cell stack. Therefore, there is a problem in that the weight of the entire fuel cell stack increases due to the addition of dedicated parts.

  In addition, the fastening bands 5 and 5 and the auxiliary plates 4a and 4b are integrally connected by the metal pin 7, and the fastening load of the fuel cell stack directly acts on the metal pin 7 as a shearing force. Furthermore, during operation of the fuel cell stack, parts are likely to expand and contract, and external forces such as shearing force may frequently act on the metal pins 7. For this reason, for example, the metal pin 7 needs to have a large diameter so that it can withstand a shearing force and the like, and there is a problem that the weight of the entire fuel cell stack increases and the size thereof increases.

  The present invention solves this type of problem, and an object of the present invention is to provide a fuel cell stack that is simple and compact, and that can improve the rigidity of a casing.

  The present invention is a fuel cell stack in which a stacked body in which a plurality of electrolyte / electrode structures each having a pair of electrodes provided on both sides of an electrolyte and a plurality of separators are stacked is housed in a box-shaped casing.

  The casing includes end plates disposed at both ends in the stacking direction of the laminate, a plurality of side plates disposed at the side portions of the laminate, and bolts that connect the end plates and the side plates. The at least one side plate is provided with a bent portion that is bent toward the end plate, and the inner surface of the bent portion and the outer surface of the end plate are in contact with each other to receive a load in the stacking direction. Part.

  Moreover, it is preferable that the end plate is provided with a recess for accommodating the bent portion. This is because the assembly accuracy between the end plate and the side plate can be obtained easily and reliably only by accommodating the bent portion of the side plate in the concave portion of the end plate.

  Furthermore, it is preferable that the bent portion and the end plate are fastened by a bolt whose axis is arranged in the stacking direction. This is because the load acting in the stacking direction can be more reliably received, and the strength of the entire casing can be increased.

  In the present invention, since the inner surface of the bent portion provided on the side plate and the outer surface of the end plate constitute a load receiving portion, the load receiving portion reliably receives the tightening load applied to the laminated body in the stacking direction. be able to. Therefore, an excessive external force such as a shearing force does not act on the bolt that connects the end plate and the side plate. Thereby, it becomes possible to improve the rigidity of a casing favorably with a simple and compact structure.

  FIG. 1 is a partially exploded schematic perspective view of a fuel cell stack 10 according to the first embodiment of the present invention, and FIG. 2 is a partial sectional side view of the fuel cell stack 10.

  As shown in FIG. 1, the fuel cell stack 10 includes a stacked body 14 in which a plurality of unit cells 12 are stacked in the horizontal direction (arrow A direction). A terminal plate 16a, an insulating plate 18 and an end plate 20a are sequentially disposed at one end in the stacking direction (arrow A direction) of the stacked body 14 toward the outside. At the other end in the stacking direction of the stacked body 14, a terminal plate 16b, an insulating spacer member 22 and an end plate 20b are sequentially disposed outward. The fuel cell stack 10 is integrally held by a casing 24 including end plates 20a and 20b each having a rectangular shape as end plates.

  As shown in FIGS. 2 and 3, each unit cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 30, and a thin plate-shaped first and second sandwiching the electrolyte membrane / electrode structure 30. Second metal separators 32 and 34 are provided. Instead of the first and second metal separators 32 and 34, for example, a carbon separator may be used.

  An oxidant gas supply for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the arrow A direction at one end edge of the unit cell 12 in the long side direction (the arrow B direction in FIG. 3). A communication hole 36a, a cooling medium supply communication hole 38a for supplying a cooling medium, and a fuel gas discharge communication hole 40b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided.

  The other end edge in the long side direction of the unit cell 12 communicates with each other in the direction of arrow A, and a fuel gas supply communication hole 40a for supplying fuel gas, and a cooling medium discharge communication hole for discharging the cooling medium. 38b and an oxidizing gas discharge communication hole 36b for discharging the oxidizing gas are provided.

  The electrolyte membrane / electrode structure 30 includes, for example, a solid polymer electrolyte membrane 42 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 44 and a cathode side electrode 46 that sandwich the solid polymer electrolyte membrane 42. With.

  The anode side electrode 44 and the cathode side electrode 46 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. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 42.

  A fuel gas flow path 48 that connects the fuel gas supply communication hole 40 a and the fuel gas discharge communication hole 40 b is formed on the surface 32 a of the first metal separator 32 facing the electrolyte membrane / electrode structure 30. The fuel gas channel 48 is constituted by, for example, a plurality of grooves extending in the arrow B direction. On the surface 32b of the first metal separator 32, a cooling medium flow path 50 that connects the cooling medium supply communication hole 38a and the cooling medium discharge communication hole 38b is formed. The cooling medium flow path 50 is configured by a plurality of grooves extending in the arrow B direction.

  The surface 34a of the second metal separator 34 facing the electrolyte membrane / electrode structure 30 is provided with, for example, an oxidant gas flow path 52 composed of a plurality of grooves extending in the direction of arrow B, and this oxidant gas. The flow path 52 communicates with the oxidant gas supply communication hole 36a and the oxidant gas discharge communication hole 36b. A cooling medium flow path 50 is integrally formed on the surface 34 b of the second metal separator 34 so as to overlap the surface 32 b of the first metal separator 32.

  A first seal member 54 is integrally formed on the surfaces 32 a and 32 b of the first metal separator 32 around the outer peripheral end of the first metal separator 32. A second seal member 56 is integrally formed on the surfaces 34 a and 34 b of the second metal separator 34 around the outer peripheral end of the second metal separator 34.

  As shown in FIG. 2, a seal 57 is interposed between the first and second seal members 54 and 56 in order to prevent the outer periphery of the solid polymer electrolyte membrane 42 from directly contacting the casing 24. Is done.

  As shown in FIG. 1, the casing 24 includes end plates 20a and 20b, which are end plates, a plurality of side plates 60a to 60d arranged on the side of the laminate 14, the end plates 20a and 20b, and the side plates 60a. And a bolt 64 for connecting to 60d. The side plates 60a to 60d are composed of thin metal plates.

  As shown in FIGS. 1 and 4, a plurality of screw holes 66a are formed on the upper and lower sides of the end plate 20a, and a recess 68a is formed by cutting out the outer side of the screw hole 66a. On the outer surface of the end plate 20a, a receiving surface 70a that forms a concave portion 68a and forms a vertical surface is formed. A plurality of screw holes 72a are formed on the left and right sides of the end plate 20a (see FIG. 1).

  As shown in FIG. 1, the end plate 20b is configured in the same manner as the end plate 20a described above, and a plurality of screw holes 66b are formed on the upper and lower sides of the end plate 20b. The end plate 20b is provided with a recess 68b by notching the outer side of the screw hole 66b, and a receiving surface 70b that forms the recess 68b and forms a vertical surface is formed on the outer surface of the end plate 20b. A plurality of screw holes 72b are formed on each of the left and right sides of the end plate 20b.

  At both ends in the short direction (arrow C direction) of the side plates 60a, 60c arranged on both sides in the arrow B direction of the laminate 14, mounting flange portions 74a that bend inwardly (in the laminate 14 side) by approximately 90 degrees. 74b. A plurality of screw holes 76a and 76b are formed in the flange portions 74a and 74b, respectively. At both ends in the longitudinal direction (arrow A direction) of the side plates 60a and 60c, plate-like projections 78a and 78b that protrude outward are provided, respectively. A plurality of hole portions 80a and 80b are formed in the plate-like protrusion portions 78a and 78b, respectively, and relief portions 81a and 81b are provided surrounding the hole portions 80a and 80b.

  The side plates 60b and 60d arranged above and below the laminated body 14 are set to have a width dimension larger than that of the side plates 60a and 60c, and constitute the long side of the casing 24, while the side plates 60a and 60c are the casing 24. The short side of At both ends in the longitudinal direction of the side plates 60b and 60d, bent portions 82a and 82b that are bent inward (end plate 20a and 20b side) by approximately 90 degrees are provided.

  Each bent portion 82a of the side plate 60b is accommodated in the upper concave portions 68a and 68b of the end plates 20a and 20b, and each bent portion 82b of the side plate 60d is lower concave portions 68a and 68b of the end plates 20a and 20b. Is housed in. As shown in FIG. 4, each bent portion 82a has a receiving surface 84a that contacts the upper receiving surfaces 70a and 70b, and each bent portion 82b receives the receiving surface 84b that contacts the lower receiving surfaces 70a and 70b. Have. The receiving surfaces 70a and 70b and the receiving surfaces 84a and 84b are in contact with each other to form a load receiving portion 85.

  As shown in FIGS. 1 and 4, the side plates 60b and 60d are formed with a plurality of holes 86a and 86b in the vicinity of the bent portions 82a and 82b, and surround the holes 86a and 86b. Portions 88a and 88b are provided. A plurality of holes 90a and 90b are formed at both ends of the side plates 60b and 60d in the direction of arrow B, respectively, surrounded by the escape portions 92a and 92b (see FIG. 1).

  As shown in FIGS. 1 and 2, the spacer member 22 has a rectangular shape set to a predetermined size so as to be positioned on the inner periphery of the casing 24. The spacer member 22 is adjusted in thickness in order to absorb a variation in the length of the stacked body 14 in the stacking direction and to apply a desired tightening load to the stacked body 14. Note that the spacer member 22 may not be used if the variation in the length of the stacked body 14 in the stacking direction can be absorbed by the elasticity of the first and second metal separators 32 and 34 themselves.

  Next, an operation of assembling the fuel cell stack 10 configured as described above will be schematically described.

  First, for example, the insulating plate 18 and the terminal plate 16a are laminated on the end plate 20a side, and a plurality of unit cells 12 are arranged on the terminal plate 16a. Then, after the predetermined number of unit cells 12 are stacked, the terminal plate 16b, the spacer member 22, and the end plate 20b are stacked.

  Further, the side plates 60 a to 60 d are arranged on the side portions of the stacked body 14 with a tightening load applied in the stacking direction between the end plates 20 a and 20 b. At that time, as shown in FIG. 2, both the bent portions 82a of the side plate 60b are accommodated in the upper concave portions 68a and 68b of the end plates 20a and 20b, while both the bent portions 82b of the side plate 60b The plates 20a and 20b are accommodated in the lower recesses 68a and 68b.

  As shown in FIG. 4, at one end of the side plates 60b, 60d on the end plate 20a side, bolts 64 are inserted into the holes 86a, 86b, and the respective tips are screw holes provided on the upper and lower sides of the end plate 20a. 66a. Thereby, the one end part of the side plates 60b and 60d is fixed to the end plate 20a.

  As shown in FIGS. 1 and 2, at the other end of the side plates 60b and 60d on the end plate 20b side, similarly, the tips of the bolts 64 introduced into the holes 86a and 86b are located on the upper and lower sides of the end plate 20b. Are screwed into the screw holes 66b. For this reason, the other ends of the side plates 60b and 60d are fixed to the end plate 20b.

  In the side plates 60a and 60b, as shown in FIG. 1, the tips of the bolts 64 inserted into the respective holes 80a and 80b are screwed into the screw holes 72a and 72b of the end plates 20a and 20b, thereby Side plates 60a and 60b are fixed to the end plates 20a and 20b. Furthermore, the front ends of the bolts 64 inserted into the holes 90a and 90b of the side plates 60b and 60d are screwed into the screw holes 76a and 76b provided in the side plates 60a and 60b, thereby the side plates 60a to 60d. They are fixed together.

In this case, in the first embodiment, for example, bent portions 82a that are bent toward the end plates 20a and 20b are provided at both ends in the direction of arrow A of the side plate 60b, and receiving surfaces 84a that constitute the inner surface of each bent portion 82a. However, the load receiving portion 85 is configured in contact with the receiving surfaces 70a and 70b constituting the outer surfaces of the end plates 20a and 20b.

  Therefore, when a tightening load is applied to the stacking direction of the stacked body 14 in which a plurality of unit cells 12 are stacked, or when an external force is generated due to expansion or contraction during operation of the fuel cell stack 10, this tightening load is generated. And external force can be reliably received through the load receiving portion 85. Thereby, excessive shearing force due to tightening load, external force, or the like does not act on the bolt 64 that connects the side plate 60b and the end plates 20a, 20b.

Moreover, since the bent portions 82a are provided at both ends of the side plate 60b in the direction of arrow A , as shown in FIG. 5, the side plate 60b is twisted in the direction of arrow D (deformation at each diagonal position). The rigidity is effectively improved. For this reason, while improving the rigidity of the whole casing 24, the advantage that the thickness reduction of the side plate 60b itself is easily performed will be acquired.

  On the other hand, the side plate 60d is similarly provided with bent portions 82b that are bent toward the end plates 20a, 20b at both ends in the direction of arrow A, and the load receiving portions 84b and the receiving surfaces 70a, 70b come into contact with each other. 85. For this reason, the casing 24 has a simple and compact configuration, and the effect that the rigidity can be improved satisfactorily is obtained.

  Further, the end plates 20a and 20b are provided with recesses 68a and 68b for accommodating the bent portions 82a and 82b. Therefore, there is an advantage that the assembling accuracy between the end plates 20a, 20b and the side plates 60b, 60d can be obtained easily and reliably only by accommodating the bent portions 82a, 82b in the recesses 68a, 68b.

  Further, since the bent portions 82a and 82b are accommodated in the recesses 68a and 68b, the rigidity against torsion of the side plates 60b and 60d is further improved, and in particular, the displacement of the laminate 14 accommodated in the casing 24 is reliably prevented. The Therefore, good power generation can be efficiently performed by each unit cell 12.

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

  In this fuel cell stack 10, first, as shown in FIG. 5, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 36a of the end plate 20a, and hydrogen is supplied to the fuel gas supply communication hole 40a. Fuel gas such as contained gas is supplied. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 38a. For this reason, in the stacked body 14, the oxidant gas, the fuel gas, and the cooling medium are supplied in the arrow A direction to the plurality of unit cells 12 stacked in the arrow A direction.

  As shown in FIG. 3, the oxidant gas is introduced into the oxidant gas flow path 52 of the second metal separator 34 through the oxidant gas supply communication hole 36 a, and along the cathode side electrode 46 of the electrolyte membrane / electrode structure 30. Move. On the other hand, the fuel gas is introduced into the fuel gas passage 48 of the first metal separator 32 through the fuel gas supply communication hole 40 a and moves along the anode side electrode 44 of the electrolyte membrane / electrode structure 30.

  Therefore, in each electrolyte membrane / electrode structure 30, the oxidant gas supplied to the cathode side electrode 46 and the fuel gas supplied to the anode side electrode 44 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 46 flows along the oxidant gas discharge communication hole 36b, and then is discharged to the outside from the end plate 20a. Similarly, the fuel gas consumed by being supplied to the anode side electrode 44 is discharged to the fuel gas discharge communication hole 40b, flows, and is discharged from the end plate 20a to the outside.

  The cooling medium flows in the direction of arrow B after being introduced into the cooling medium flow path 50 between the first and second metal separators 32 and 34 from the cooling medium supply communication hole 38a. The cooling medium cools the electrolyte membrane / electrode structure 30, and then moves through the cooling medium discharge communication hole 38b and is discharged from the end plate 20a.

  In the first embodiment, the load receiving portions 85 are provided on the two upper and lower side plates 60b and 60d and the end plates 20a and 20b. However, the present invention is not limited to this. For example, the side plate 60b Only the load receiving portion 85 may be provided. Similarly, in the other side plates 60a and 60c, the load receiving portion 85 may be provided in at least one of them, or the load receiving portion 85 may be provided in all the side plates 60a to 60d. The same applies to the second embodiment described below.

[Reference example]
FIG. 6 is a partially exploded schematic perspective view of a fuel cell stack 100 according to the second embodiment of the present invention, and FIG. 7 is a partially enlarged cross-sectional view of the fuel cell stack 100. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell stack 100 includes a casing 102, and one or more side plates constituting the casing 102, for example, bent portions 82a bent toward the end plates 20a and 20b, respectively, at both ends in the direction of arrow A of the side plates 60b and 60d, 82b is provided. A plurality of holes 104a and 104b are formed in the bent portions 82a and 82b, respectively, penetrating in the direction of the arrow A.

  In the end plate 20a, screw holes 106a are formed penetrating in the direction of arrow A in receiving surfaces 70a and 70b constituting recesses 68a and 68a provided at both upper and lower edges. Similarly, the end plate 20b penetrates in the direction of arrow A through the receiving surface 70b constituting the recess 68b, and a screw hole 106b is formed.

  In the fuel cell stack 100 configured as described above, the bent portions 82a and 82b provided at one ends of the side plates 60b and 60d are accommodated in the recesses 68a of the end plate 20a. Then, the bolt 64 is inserted into the hole portions 104a and 104b of the bent portions 82a and 82b, and the respective ends thereof are screwed into the screw holes 106a (see FIG. 7). Thereby, one end of the side plates 60b and 60d and the end plate 20a are fixed integrally.

  Similarly, bent portions 82a and 82b provided at the other ends of the side plates 60b and 60d are accommodated in the recesses 68b of the end plate 20b. Further, the bolts 64 are screwed into the screw holes 106b through the holes 10a and 104b, whereby the other ends of the side plates 60b and 60d and the end plate 20b are fixed integrally.

  In this case, in the second embodiment, the axis of the bolt 64 for connecting the side plates 60b, 60d and the end plates 20a, 20b coincides with the stacking direction of the unit cells 12 (arrow A direction). For this reason, the bolt 64 can reliably receive the tightening load or external force in the stacking direction that acts on the fuel cell stack 100, and the casing 102 can further increase the overall strength.

1 is a partially exploded schematic perspective view of a fuel cell stack according to a first embodiment of the present invention. It is a partial cross section side view of the said fuel cell stack. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said fuel cell stack. It is a partial expanded sectional view of the fuel cell stack. It is a perspective view of the fuel cell stack. FIG. 4 is a partially exploded schematic perspective view of a fuel cell stack according to a second embodiment of the present invention. It is a partial expanded sectional view of the fuel cell stack. 2 is an explanatory diagram of a fuel cell stack of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 ... Fuel cell stack 12 ... Unit cell 14 ... Laminated body 20a, 20b ... End plate 24, 102 ... Casing 30 ... Electrolyte membrane and electrode structure 32, 34 ... Metal separator 42 ... Solid polymer electrolyte membrane 44 ... Anode Side electrode 46 ... Cathode side electrode 48 ... Fuel gas flow path 50 ... Cooling medium flow path 52 ... Oxidant gas flow path 60a-60d ... Side plate 64 ... Bolts 66a, 66b, 72a, 72b ... Screw holes 68a, 68b ... Recess 70a , 70b, 84a, 84b ... receiving surfaces 76a, 76b, 106a, 106b ... screw holes 80a, 80b, 86a, 86b, 90a, 90b, 104a, 104b ... holes 82a, 82b ... bent portions 85 ... load receiving portions

Claims (1)

A fuel cell stack that accommodates a laminate in which a plurality of separators and an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte is contained in a box-shaped casing,
The separator is formed in a thin corrugated shape, sandwiching the electrolyte-electrode structure,
The casing includes end plates disposed at both ends in the stacking direction of the stacked body,
A plurality of side plates disposed on the side of the laminate;
A bolt connecting the side surface of the end plate and the side plate;
With
At least one of the side plates is provided with a bent portion that is bent toward the end plate,
The end plate is provided with a recess for accommodating the bent portion,
The fuel cell stack, wherein an inner surface of the bent portion and an outer surface of the concave portion are in surface contact with each other to form a load receiving portion for receiving a load in a stacking direction.

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