JP5214260B2 - Fuel cell stack - Google Patents

Description

  The present invention includes a unit cell in which an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is contained in a box-shaped casing. It relates to a battery stack.

  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 disposed 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 disclosed in Patent Document 1 is known. As shown in FIG. 7, the fuel cell stack includes a cell row 2 in which several single cells 1 are stacked, and a cylinder with a movable end plate 3 disposed at one end of the cell row 2. 4 is accommodated. The movable end plate 3 is movable in the stacking direction of the single cells 1 with respect to the cylinder 4.

  A fixed end plate 5 is disposed at the end of the cell row 2 opposite to the movable end plate 3, and the opening end of the cylinder 4 on the movable end plate 3 side is closed via a spring retainer 6. ing.

  The movable end plate 3 is divided into an inner part 3a and an outer part 3b, and individual springs are provided between the inner part 3a and the spring retainer 6 and between the outer part 3b and the spring retainer 6, respectively. An inner spring 7a and an outer spring 7b as elements are interposed.

JP 2004-335336 A

  By the way, in the fuel cell stack described above, the cell row 2 is accommodated in the cylinder 4, and the movable end plate 3, the inner spring 7 a and the outer spring 7 b are disposed at one end of the cell row 2. ing. For this reason, the fuel cell stack is considerably elongated in the stacking direction (arrow L direction) of the cell rows 2, and there is a problem that the fuel cell stack cannot be reduced in size. In particular, when used as an in-vehicle fuel cell stack, it is necessary to effectively use a small space, and there is a possibility that the above-described conventional technology cannot cope with it.

  The present invention solves this type of problem, and an object thereof is to provide a fuel cell stack capable of reliably applying a desired load to a laminate for a long period of time with a simple and compact configuration. .

  The present invention includes a unit cell in which an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is contained in a box-shaped casing. It relates to a battery stack.

  The casing is provided on the end plate disposed at both ends in the stacking direction of the laminate, the plurality of side plates disposed on the side of the laminate, the end plate and the side plate, and for inserting the connection pin. An end plate side support portion and a side plate side support portion, and the end plate side support portion and the side plate side support portion are arranged in the axial direction of the connection pin in order to cause elastic bending deformation of the connection pin. They are alternately arranged apart from each other.

And when the tightening load at the time of mounting in the stacking direction is applied to the stacked body, the distance between the axes of the side plate side support portions provided at both ends of the side plate in the stacking direction is the end plate side support provided on each end plate. It is set to be shorter than the distance between the axes of the parts.

  Furthermore, the end plate side support portion and the side plate side support portion preferably have a curved surface that bulges toward the center of the hole on the inner wall surface of the hole into which the connecting pin is inserted.

  In the present invention, when the connecting pin is inserted into the end plate side support part and the side plate side support part, the end plate side support part and the side plate side support part are separated from each other, and the connecting pin is elastically bent and deformed. Will occur. For this reason, when expansion and contraction in the stacking direction occurs in the stacked body, the expansion and contraction amount of the stacked body can be absorbed by the elasticity of the connecting pin. Therefore, even if a sag or the like is caused in the laminated body, a stable tightening force can be applied to the laminated body by the elastic action of the connecting pin. As a result, the fuel cell stack can be used satisfactorily for a long period of time with a simple and compact configuration.

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

  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 (the insulating plate 18 may be used) 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.

  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 edge of the first metal separator 32. The first seal member 54 surrounds the fuel gas supply communication hole 40a, the fuel gas discharge communication hole 40b, and the fuel gas flow path 48 on the surface 32a so as to communicate with each other, and on the surface 32b, the cooling medium supply communication hole 38a, The medium discharge communication hole 38b and the cooling medium flow path 50 are surrounded and communicated with each other.

  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 edge of the second metal separator 34. The second seal member 56 surrounds and communicates the oxidant gas supply communication hole 36a, the oxidant gas discharge communication hole 36b, and the oxidant gas flow path 52 on the surface 34a, while the cooling medium supply communication hole on the surface 34b. 38a, the cooling medium discharge communication hole 38b, and the cooling medium flow path 50 are surrounded and communicated.

  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, rod-shaped terminal portions 58a and 58b projecting in the stacking direction are formed at substantially the center portions of the terminal plates 16a and 16b. For example, a load such as a traveling motor is connected to the terminal portions 58a and 58b.

  The casing 24 is an angle member that connects end plates 20a and 20b, which are end plates, a plurality of side plates 60a to 60d disposed on the side of the laminated body 14, and end portions of the side plates 60a to 60d that are close to each other. (For example, L angle) 62a to 62d, and connection pins 64a and 64b having different lengths for connecting the end plates 20a and 20b and the side plates 60a to 60d, respectively.

  The side plates 60a to 60d are made of, for example, a thin metal plate. The side plates 60a to 60d are fixed to each other via angle members 62a to 62d and bolts 65, and the casing 24 is configured (see FIG. 4).

  Two first support portions (end plate side support portions) 66a and 66b are formed to protrude on the upper and lower sides of the end plates 20a and 20b, respectively, and one first support portion is provided on each side of each side. (End plate side support portions) 66c and 66d are formed to protrude. Holes 67a to 67d are formed through the first support portions 66a to 66d.

  Two second support portions (side plate side support portions) 70a and 70b are formed at both ends in the longitudinal direction (arrow A direction) of the side plates 60a and 60c arranged on both sides in the arrow B direction of the laminate 14. Three second support portions (side plate side support portions) 72a and 72b are formed at both ends in the longitudinal direction of the side plates 60b and 60d disposed on the upper and lower sides of the laminate 14 respectively. Holes 71a and 71b are formed in the second support portions 70a and 70b, and holes 73a and 73b are formed in the second support portions 72a and 72b.

  As shown in FIG. 4, between the second support portions 70a, 70b of the side plates 60a, 60c, first support portions 66c, 66d on both sides of the end plates 20a, 20b are arranged. A short connecting pin 64a is inserted integrally.

  Similarly, the second support portions 72a and 72b of the side plates 60b and 60d are alternately arranged with the first support portions 66a and 66b on the upper side and the lower side of the end plates 20a and 20b, and the long connecting pins 64b. Are integrally inserted.

  As shown in FIG. 5, the first support portions 66a and 66b and the second support portion 72a are mutually connected in the axial direction (arrow B direction) of the connection pin 64b in order to cause elastic bending deformation of the connection pin 64b. Alternatingly spaced apart by a distance S. This distance S is set based on the rigidity and diameter of the connecting pin 64b, the elasticity of the entire laminate 14, the required tightening load, and the like.

  When a tightening load is applied to the laminate 14 in the stacking direction, the distance L1 between the axes of the second support portions 72a and 72a provided at both ends of the side plate 60b in the stacking direction (arrow A direction) The distance is set shorter than the distance L2 between the axes of the first support portions 66a and 66b provided on the plates 20a and 20b (distance L1 <distance L2).

  As shown in FIG. 6, a curved surface 74 bulging toward the center of the hole is provided on the inner wall surface of the holes 67a and 67b of the first support portions 66a and 66b. A curved surface 76 that bulges toward the center of the hole is provided on the inner wall surface of the hole 73a of the second support portion 72a. The curved surfaces 74 and 76 constitute a guide surface for satisfactorily performing elastic bending deformation of the connecting pin 64b, and may be provided at least on the inner wall surface in the bending direction.

  The relationship between the first support portions 66a and 66b and the second support portions 72b and 72b, the relationship between the first support portions 66c and 66d and the second support portions 70a and 70a, and the first support portions 66c and 66d. The relationship between the second support portions 70b and 70b is the same as the relationship between the first support portions 66a and 66b and the second support portions 72a and 72a, and a detailed description thereof will be omitted.

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

  First, when assembling the fuel cell stack 10, the side plates 60 a to 60 d are fixed to each other via the angle members 62 a to 62 d and the bolts 65, and the laminated body 14 in which a predetermined number of unit cells 12 are stacked includes the side plate. It arrange | positions in 60a-60d.

  Next, end plates 20a and 20b are disposed at both ends in the stacking direction of the stacked body 14, while a load larger than the tightening load at the time of mounting is once applied to the stacked body 14 in the stacking direction. Therefore, in the laminate 14, the electrolyte membrane / electrode structure 30, the first metal separator 32, and the second metal separator 34 are compressed in the stacking direction, and the entire stack 14 is compressed and held in the stacking direction.

  In this state, the connecting pin 64a is integrally inserted into the second support portions 70a and 70b of the side plates 60a and 60c and the first support portions 66c and 66d of the end plates 20a and 20b. Similarly, the connecting pin 64b is integrally inserted into the second support portions 72a and 72b of the side plates 60b and 60d and the first support portions 66a and 66b of the end plates 20a and 20b. Thereby, the casing 24 is assembled.

  As described above, after the casing 24 is assembled, the application of the load to the stacked body 14 is released. Therefore, since the compressive force in the stacking direction is released, the stacked body 14 is expanded outward in the stacking direction by its own elasticity.

  In this case, in the present embodiment, as shown in FIG. 5, the first support portions 66a and 66b and the second support portions 72a and 72a are alternately arranged with a distance S therebetween, and the stacked body 14 When the tightening load at the time of mounting is applied in the stacking direction, the distance L1 between the axes of the second support portions 72a and 72a is set shorter than the distance L2 between the axes of the first support portions 66a and 66b. Has been.

  Therefore, the end plates 20a and 20b are pressed and moved outward in the stacking direction, and the connecting pins 64a and 64b are elastically bent and deformed. Accordingly, the connecting pins 64a and 64b have a spring function and press the end plates 20a and 20b inward in the stacking direction.

  Here, for example, as shown in FIG. 6, curved surfaces 74 and 76 are provided on the inner wall surfaces of the holes 67a and 67b of the first support portions 66a and 66b and the inner wall surface of the hole 73a of the second support portion 72a. ing. Thereby, the elastic bending deformation of the connecting pin 64b is performed satisfactorily and reliably.

  Next, when the fuel cell stack 10 is operated, first, as shown in FIG. 4, 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 the fuel A fuel gas such as a hydrogen-containing gas is supplied to the gas supply communication hole 40a. 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 this case, in the fuel cell stack 10 described above, the connecting pins 64a and 64b are elastically bent and deformed to press the end plates 20a and 20b toward each other in the stacking direction (see FIG. 5). ). For this reason, when expansion / contraction occurs in the laminate 14, the expansion / contraction amount of the laminate 14 can be absorbed by the elasticity of the connecting pins 64a and 64b itself.

  Therefore, even when a sag or the like is caused in the laminated body 14 due to the long-term use, it is possible to reliably give a stable fastening force to the laminated body 14 under the elastic action of the connecting pins 64a and 64b. It becomes possible. Thereby, the effect that the fuel cell stack 10 can be used satisfactorily for a long time with a simple and compact configuration is obtained. Moreover, there is an advantage that an elastic member such as a disc spring for absorbing the expansion and contraction of the laminated body 14 is unnecessary at the end of the laminated body 14.

1 is a partially exploded schematic perspective view of a fuel cell stack according to an embodiment of the present invention. 2 is a cross-sectional side view of the fuel cell stack. FIG. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said fuel cell stack. It is a perspective view of the fuel cell stack. FIG. 2 is an explanatory plan view of the fuel cell stack. FIG. 4 is a partially enlarged plan explanatory view of the fuel cell stack. 2 is a cross-sectional view of a fuel cell stack disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Unit cell 14 ... Laminated body 16a, 16b ... Terminal plate 18 ... Insulating plate 20a, 20b ... End plate 22 ... Spacer member 24 ... Casing 30 ... Electrolyte membrane and electrode structure 32, 34 ... Metal separator DESCRIPTION OF SYMBOLS 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 54, 56 ... Sealing member 60a-60d ... Side plate 62a-62d ... Angle members 64a, 64b ... Connecting pins 66a-66d, 70a, 70b, 72a, 72b ... Support portions 67a-67d, 71a, 71b, 73a, 73b ... Holes 74, 76 ... Curved surfaces

Claims (2)

A fuel cell stack comprising a unit cell in which a pair of electrodes provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is housed in a box-shaped casing. And
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;
An end plate side support portion and a side plate side support portion that are provided on the end plate and the side plate and for inserting a connection pin;
Equipped with a,
And said end plate side supporting portion and the side plate side support portion, in order to generate an elastic bending deformation to the connecting pins, with Ru are alternately arranged spaced apart from one another in the axial direction of the connecting pins,
When a tightening load is applied to the laminate in the stacking direction, the distance between the axes of the side plate support portions provided at both ends of the side plate in the stacking direction is the end plate side support provided on each end plate. A fuel cell stack, characterized in that the fuel cell stack is set to be shorter than the distance between the axes of the parts . The fuel cell stack according to claim 1 Symbol mounting, said end plate side supporting portion and the side plate side support portion, the hole inner wall surface in which the connecting pin is inserted, to have a curved surface bulging into the hole center side A fuel cell stack characterized by

Images