JP2005100755A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an end plate thinner and allow mounting members to be fixed to the end plate firmly and surely by screw. <P>SOLUTION: A plurality of first to third bosses 74a to 74c are mounted on a first end plate 20a by protruding from the outer surface 68a corresponding to mounting positions of a mount bracket 70 and manifold piping members 72a, 72b. Male screws 76a to 76c are formed in the bosses 74a to 74c respectively. The mount bracket 70 and the manifold piping members 72a, 72b are mounted on the first end plate 20a through bolts 82 screwed with the male screws 76a to 76c. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a unit cell in which an electrolyte / electrode structure having electrodes provided on both sides of an electrolyte is sandwiched between a pair of separators, and a fuel in which a stack in which a plurality of the unit cells are stacked is sandwiched between a pair of end plates. 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 (cation exchange membrane). The electrolyte membrane / electrode structure in which the anode side electrode and the cathode side electrode in which a noble metal-based electrode catalyst layer is bonded to a base material mainly composed of carbon is disposed on both sides of the electrolyte membrane is sandwiched by a separator to A battery is configured.

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

  Usually, this type of fuel cell is a fuel in which a predetermined number (for example, several tens to several hundreds) is laminated to form a laminated body, and the laminated body is sandwiched between a pair of end plates in order to obtain a desired power generation. Battery stack is in use. 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, the chemical electric fuel cell stack of Patent Document 1 is known. In this fuel cell stack, as shown in FIG. 9, a plurality of fuel cells 1 are stacked on a lower end plate 2, and a current collecting plate 3 is disposed on the stacked fuel cells 1. An upper end plate 4 is disposed on the current collecting plate 3, and a plurality of screw holes 5 are formed in the upper end plate 4, and screws 6 are screwed into the screw holes 5.

  The lower end plate 2 and the upper end plate 4 are clamped and held via a tie rod assembly 7. The tie rod assembly 7 includes tie rods 8 disposed at the four corners of the fuel cell stack, and nuts 9 that are screwed into the tips of the tie rods 8.

  In this fuel cell stack, the outer peripheral side of the fuel cell stack is tightened and held by the tie rod assembly 7, while the selected screw 6 is tightened with a uniform torque, so that a uniform tightening load is applied to the surface of the current collecting plate 3. Is granted. Therefore, the upper end plate 4 can be thinned by using the screws 6.

European patent application EP1094536 (Fig. 1)

  By the way, in the above Patent Document 1, it is possible to reduce the thickness of the upper end plate 4, but it is difficult to fix an attachment member such as a pipe manifold to the upper end plate 4. Has been pointed out. This is because when a screw hole is formed in the upper end plate 4 itself, a desired axial length cannot be ensured and it is difficult to maintain the tightening strength by screwing.

  The present invention solves this type of problem, and aims to provide a fuel cell stack capable of reducing the thickness of the end plate and firmly and securely screwing the mounting member.

  The fuel cell stack of the present invention includes a unit cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte is sandwiched by a pair of separators, and a stacked body in which a plurality of the unit cells are stacked is a pair of end plates. It is pinched with. At least one of the end plates is provided with a boss portion that protrudes from the outer surface opposite to the laminated body and is formed with an internal thread. For example, an attachment member is screwed to the boss portion. In that case, it is preferable that the attachment member is provided with a relief portion for avoiding the boss portion on the contact surface with the end plate.

  Further, a box-shaped casing that accommodates the laminated body is provided, and the box-shaped casing is connected to the end plate that is disposed on both ends of the laminated body in the stacking direction, and is disposed on a side portion of the stacked body. It is preferable to provide a plurality of side plates.

  According to the present invention, since the boss portion protruding from the outer surface of the end plate is provided, a relatively long female screw can be formed on the boss portion even if the end plate is configured to be thin. Therefore, the end plate can be satisfactorily thinned, and the mounting member can be firmly and securely screwed.

  Further, since the boss portion is accommodated in the relief portion provided in the attachment member, the attachment member can be reliably brought into contact with the outer surface of the end plate. As a result, the attachment member can be firmly fixed to the end plate.

  Furthermore, since the laminate is accommodated in the box-shaped casing and the end plate constitutes the box-shaped casing, the entire fuel cell stack can be easily reduced in size. In addition, the end plate can be made thinner by holding the laminate in the entire box-like casing.

  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.

  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 18a, and a first end plate 20a are sequentially arranged 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 plate 18b, and a second end plate 20b are sequentially disposed outward. The fuel cell stack 10 is integrally held by a box-shaped casing 24 that includes first and second end plates 20a, 20b configured in a substantially 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 composed of a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles carrying a platinum alloy on the surface are uniformly applied to the surface of the gas diffusion layer. And have. The electrode catalyst layers are bonded to both surfaces of the solid polymer electrolyte membrane 42 so as to face each other with the solid polymer electrolyte membrane 42 interposed therebetween.

  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. 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 end 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 box-shaped casing 24. The The outer peripheral ends of the first and second seal members 54 and 56 may have a slight gap with the inner surface of the box-shaped casing 24, or may be in contact with the inner surface. This is to restrict the first and second metal separators 32 and 34 from bending beyond a predetermined amount.

  As shown in FIGS. 1 and 2, plate-like terminal portions 58a and 58b protruding in the surface direction are formed at the ends 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.

  As shown in FIG. 1, the box-shaped casing 24 includes first and second end plates 20 a and 20 b which are end plates, a plurality of side plates 60 a to 60 d disposed on the side of the laminated body 14, and the first And connecting pins 64a and 64b having different lengths for connecting the second end plates 20a and 20b and the side plates 60a to 60d.

  Two tab portions 66a and 66b project from the upper and lower sides of the first and second end plates 20a and 20b, respectively, and one tab portion 66a and 66b project from the sides on both sides. Is done.

  As shown in FIG. 4, a mounting bracket (mounting member) 70 is attached to the outer surface (the outer surface opposite to the laminated body 14) 68 a of the first end plate 20 a at the center lower side in the width direction (arrow B direction). Manifold piping members (attachment members) 72a and 72b are attached to both sides in the width direction of the outer surface 68a.

  As shown in FIG. 5, a plurality of, for example, four first boss portions 74a are provided on the lower side of the center of the first end plate 20a so as to protrude from the outer surface 68a corresponding to the mounting position of the mount bracket 70. On both sides in the width direction of the first end plate 20a, a plurality of, for example, eight second and third boss portions 74b and 74c respectively protrude from the outer surface 68a corresponding to the mounting positions of the manifold piping members 72a and 72b. Provided.

  As shown in FIG. 6, the first boss portion 74a is fixed by welding, adhesion or the like in a state of being inserted into the first end plate 20a, and a female screw 76a is formed on the first boss portion 74a. The The axial length H1 of the female screw 76a is set to a dimension larger than the thickness (thickness) H2 of the first end plate 20a. The second and third boss portions 74b and 74c are configured in the same manner as the first boss portion 74a, and female screws 76b and 76c each having a desired axial length are formed (see FIG. 5).

  As shown in FIGS. 5 and 6, the mount bracket 70 is provided with a plurality of relief portions 80 for avoiding the first boss portions 74a on the contact surface 78 with the first end plate 20a. The mount bracket 70 is fixed to the first end plate 20a by screwing the bolt 82 into the female screw 76a of the first boss portion 74a, and is fixed to the mounting portion via the bolt 84, whereby the fuel cell stack. 10 is mounted on a vehicle, for example.

  As shown in FIG. 5, the manifold piping member 72a includes pipings 86a, 88a, and 90b connected to the oxidant gas supply communication hole 36a, the cooling medium supply communication hole 38a, and the fuel gas discharge communication hole 40b, respectively. The manifold piping member 72a is provided with a relief portion 94a for avoiding the second boss portion 74b on the contact surface 92a with the first end plate 20a. The manifold piping member 72a is fixed to the first end plate 20a by screwing the bolt 82 into the female screw 76b of the second boss portion 74b.

  The manifold piping member 72b includes piping 90a, 88b, and 86b connected to the fuel gas supply communication hole 40a, the cooling medium discharge communication hole 38b, and the oxidant gas discharge communication hole 36b, respectively. The manifold piping member 72b is provided with a relief portion 94b for avoiding the second boss portion 74b on the contact surface 92b with the first end plate 20a. The manifold piping member 72b is fixed to the first end plate 20a by screwing the bolt 82 into the female screw 76c of the third boss portion 74c.

  As shown in FIG. 2, a mounting bracket 70 is similarly attached to the outer surface 68b of the second end plate 20b via bolts 82, and detailed description thereof is omitted.

  As shown in FIGS. 1 and 4, two tab portions 100 a and 100 b are formed at both longitudinal ends of the side plates 60 a and 60 c arranged on both sides of the laminate 14. The side plates 60b and 60d arranged above and below the laminated body 14 are bent and formed in a U-shaped cross section, and three tab portions 102a and 102b are formed at both ends in the longitudinal direction.

  Between the tab portions 100a and 100b of the side plates 60a and 60c, tab portions 66a and 66b on both sides of the first and second end plates 20a and 20b are arranged, and a short connecting pin 64a is integrally formed therewith. Inserted, the side plates 60a, 60c are attached to the first and second end plates 20a, 20b.

  Similarly, the tab portions 102a and 102b of the side plates 60b and 60d are alternately arranged with the tab portions 66a and 66b on the upper side and the lower side of the first and second end plates 20a and 20b, and the long connecting pins 64b are connected thereto. Are integrally inserted, and the side plates 60b and 60d are attached to the first and second end plates 20a and 20b.

  A plurality of holes 104 are formed in both lateral edges of the side plates 60a and 60b, respectively, while a plurality of screw holes 106 corresponding to the holes 104 are formed in the bent portions of the side plates 60c to 60d. It is formed. When the screws 108 inserted into the holes 104 are screwed into the screw holes 106, the side plates 60a to 60d are fixed to each other. Thereby, the box-shaped casing 24 is comprised (refer FIG. 4).

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

  First, as shown in FIGS. 4 and 5, in the fuel cell stack 10, an oxidant gas such as an oxygen-containing gas is supplied from the pipe 86a of the manifold pipe member 72a to the oxidant gas supply communication hole 36a. Fuel gas such as hydrogen-containing gas is supplied from the pipe 90a of the member 72b to the fuel gas supply communication hole 40a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied from the piping 88a of the manifold piping member 72a to the cooling medium supply communication hole 38a.

  For this reason, as shown in FIGS. 1 and 2, in the stacked body 14, the oxidant gas, the fuel gas, and the cooling medium are supplied in the direction of arrow A to the plurality of unit cells 12 stacked in the direction of arrow A. The

  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 supplied to and consumed by the cathode side electrode 46 flows along the oxidant gas discharge communication hole 36b, and then is discharged to the outside from the pipe 86b of the manifold pipe member 72b (FIGS. 4 and 4). 5). Similarly, the fuel gas consumed by being supplied to the anode side electrode 44 is discharged and flows into the fuel gas discharge communication hole 40b, and is discharged to the outside from the pipe 90b of the manifold pipe member 72a.

  Further, as shown in FIG. 3, the cooling medium is introduced along the cooling medium flow path 50 between the first and second metal separators 32 and 34 from the cooling medium supply communication hole 38a, and then flows along the arrow B direction. To do. After cooling the electrolyte membrane / electrode structure 30, the cooling medium moves through the cooling medium discharge communication hole 38b and is discharged to the outside from the pipe 88b of the manifold pipe member 72b (see FIGS. 4 and 5).

  In this case, in the present embodiment, as shown in FIG. 5, the first end plate 20a is provided with first to third boss portions 74a, 74b and 74c protruding from the outer surface 68a, and the first to first bosses are provided. Female screws 76a, 76b and 76c are formed on the three boss portions 74a, 74b and 74c. The mount bracket 70 is fixed to the first end plate 20a by screwing the bolt 82 into the female screw 76a of the first boss portion 74a. Similarly, the manifold piping members 72a and 72b are fixed to the first end plate 20a by screwing the bolts 82 into the female threads 76b and 76c of the second and third boss portions 74b and 74c.

  At that time, the axial length H1 of the female screw 76a is set to be larger than the thickness H2 of the first end plate 20a (see FIG. 6). For this reason, even if the 1st end plate 20a is comprised thinly, the comparatively long internal thread 76a can be formed in the 1st boss | hub part 74a. Similarly, relatively long female screws 76b and 76c are formed in the second and third boss portions 74b and 74c.

  Accordingly, the first end plate 20a is thinned well, and the mounting bracket 70 and the manifold piping members 72a and 72b, which are mounting members, can be firmly and securely screwed to the first end plate 20a. The effect of becoming is obtained.

  Further, the mount bracket 70 is provided with a relief portion 80, and the first boss portion 74 a is accommodated in the relief portion 80. Accordingly, the contact surface 78 of the mount bracket 70 can be reliably brought into contact with the outer surface 68a of the first end plate 20a, and the mount bracket 70 can be firmly fixed to the first end plate 20a. Become. The manifold piping members 72a and 72b also have the same effect as the mount bracket 70.

  Furthermore, while the laminated body 14 is accommodated in the box-shaped casing 24, the box-shaped casing 24 includes first and second end plates 20a, 20b disposed at both ends of the laminated body 14 in the stacking direction, A plurality of side plates 60a to 60d disposed on the side of the laminate 14 and connected to the first and second end plates 20a and 20b are provided.

  For this reason, the first and second end plates 20a and 20b are connected to the side plates 60a to 60d and the parallelism is reliably maintained, and the laminated body 14 can be held by the entire box-shaped casing 24. Thereby, the first and second end plates 20a and 20b have an advantage that a uniform tightening force is applied to the laminated body 14 and thinning is further promoted better.

  In the present embodiment, as shown in FIG. 6, the first boss portion 74a (the same applies to the second and third boss portions 74b and 74c) is fixed to the first end plate 20a by welding or adhesion. However, the present invention is not limited to this. For example, as shown in FIG. 7, the first boss portion 74a may be integrally formed with the first end plate 20a by casting or the like, and as shown in FIG. 8, two third boss portions 74c are formed. It may be integrated and fixed to the first end plate 20a.

1 is a partially exploded schematic perspective view of a fuel cell stack according to an 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 perspective view of the fuel cell stack. It is a disassembled perspective explanatory drawing of the 1st end plate and attachment member which comprise the said fuel cell stack. FIG. 3 is a partial cross-sectional view of the first end plate. FIG. 4 is a partial cross-sectional view of a state where a boss portion is integrally formed with the first end plate. FIG. 5 is a partial perspective view of a state in which two boss portions are integrated and fixed to the first end plate. 2 is a schematic explanatory diagram of a fuel cell stack of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Unit cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulating plate 20a, 20b ... End plate 24 ... Box-shaped 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 ... Coolant flow path 52 ... Oxidant gas flow path 60a-60d ... Side plates 68a, 68b ... Outer surface 70 ... Mount bracket 72a, 72b ... manifold piping members 74a-74c ... bosses 76a-76c ... female threads 78, 92a, 92b ... contact surfaces 80, 94a, 94b ... relief parts 82, 84 ... bolts 86a, 86b, 88a, 88b, 90a, 90b …Piping

Claims (3)

A fuel cell stack comprising a unit cell in which an electrolyte / electrode structure having electrodes provided on both sides of an electrolyte is sandwiched by a pair of separators, and a laminate in which a plurality of the unit cells are stacked is sandwiched by a pair of end plates. And
At least one of the end plates is provided with a boss portion that protrudes from the outer surface opposite to the laminated body and in which an internal thread is formed. The fuel cell stack according to claim 1, further comprising an attachment member screwed to the boss portion.
The fuel cell stack, wherein the attachment member is provided with a relief portion for avoiding the boss portion on a contact surface with the end plate. The fuel cell stack according to claim 1 or 2, further comprising a box-shaped casing that accommodates the stack.
The box-shaped casing includes the end plates disposed at both ends in the stacking direction of the stacked body,
A plurality of side plates arranged on the side of the laminate and connected to the end plate;
A fuel cell stack comprising:

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