JP5028856B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. This fuel cell is environmentally superior and can realize high energy efficiency, and therefore has been widely developed as a future energy supply system.

  Some fuel cells have a structure in which a membrane electrode assembly in which an anode electrode and a cathode electrode are bonded to both sides of a solid polymer electrolyte membrane is laminated via a separator. In a fuel cell having such a configuration, a technique is disclosed in which a seal member is sandwiched between constituent members for the purpose of preventing gas leakage from the constituent members (see, for example, Patent Document 1).

JP 2004-6104 A

  However, in the technique of Patent Document 1, the seal member is supported only by the fastening force of the constituent members. Therefore, there is a risk that gas leakage may occur due to the sealing member being pushed out by gas pressure or the like.

  An object of this invention is to provide the fuel cell which can suppress the gas leak from a sealing member.

  A fuel cell according to the present invention includes a laminate in which a seal gasket-integrated membrane electrode assembly including a seal gasket and separators are alternately laminated, and an external restraining member disposed on a side wall along the lamination direction of the laminate. The load direction conversion means converts the load applied between the external restraining member and the seal gasket into the stacking direction of the stacked body.

  In the fuel cell according to the present invention, the load applied between the external restraining member and the seal gasket is converted into the stacking direction in the stacked body by the load direction converting means. In this case, the seal load between the seal gasket and the separator increases. Thereby, the protrusion of the seal gasket to the external restraint member side can be suppressed. As a result, gas leakage from the seal gasket can be prevented.

  The load direction converting means may be constituted by a protruding member provided on the seal gasket side of the external restraining member and a notch formed on the seal gasket and facing the protruding member. In this case, the projecting member tries to spread the seal gasket in the stacking direction of the laminate when the seal gasket tries to move toward the external restraint member. That is, the load generated between the protruding member and the seal gasket is converted to the stacking direction of the laminate and applied to the seal gasket. Thereby, the seal load between the seal gasket and the separator increases. As a result, gas leakage from the seal gasket can be prevented.

  The protruding member may have a tapered shape whose width increases from the seal gasket side to the external restraint member side. In this case, when the position of the seal gasket is shifted toward the external restraint member, the protruding member serves as a stopper for the seal gasket. Therefore, the position shift of the seal gasket can be suppressed. Further, the protruding member tends to spread the seal gasket in the stacking direction of the laminate when the seal gasket is about to move to the external restraint member side. That is, the load generated between the protruding member and the seal gasket is converted to the stacking direction of the laminate and applied to the seal gasket. Thereby, the seal load between the seal gasket and the separator increases. As a result, gas leakage from the seal gasket can be prevented.

  The tip of the protruding member on the seal gasket side may be spherical. In this case, when the position of the seal gasket is shifted toward the external restraint member, the protruding member serves as a stopper for the seal gasket. Further, when the seal gasket tries to move toward the external restraint member, the sealing load between the seal gasket and the separator increases. As a result, gas leakage from the seal gasket can be prevented.

  The load direction conversion means may be composed of a cut provided on the end face on the external restraint member side in the seal gasket and an insertion member inserted into the cut. In this case, the insertion member tries to spread the seal gasket in the stacking direction of the laminated body when the seal gasket tries to move toward the external restraint member. Thereby, the seal load between the seal gasket and the separator increases. Further, it is easy to align the notch and the insertion member. Further, the insertion member may have a tapered shape whose width increases toward the external restraint member. Further, the tip of the insertion member on the seal gasket side may be spherical.

  A manifold for allowing fluid to flow may be formed in the seal gasket. In this case, when the fluid pressure increases, the seal gasket tends to protrude toward the external restraint member. However, the protruding member can prevent the seal gasket from protruding.

  The external restraint member may be made of a rigid body, and at least the surface of the external restraint member on the seal gasket side may be made of an insulator. In this case, a short circuit in the laminate can be prevented. Further, the external restraining member may be made of an elastic body having insulating properties. In this case, the external restraint member applies a certain load to the laminate. The external restraint member is deformed according to the position of the separator and seal gasket integrated membrane electrode assembly. Thereby, the external restraint member can suppress a rapid load fluctuation in the fuel cell due to an external force or the like.

  According to the present invention, gas leakage from the seal gasket can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a sectional view schematically showing a fuel cell 100 according to a first embodiment of the present invention. As shown in FIG. 1, the fuel cell 100 has a stack structure including a stacked body 50 and an external restraining member 60. In the stacked body 50, a plurality of fuel cells 51 are stacked, and one end thereof is provided with a fluctuation absorbing member 52 (for example, a disc spring) for absorbing fluctuations in the surface pressure of the fuel cells 51, and end plates 53a, The plurality of fuel cells 51 and the fluctuation absorbing member 52 are sandwiched by 53b. The external restraint member 60 is a plate-like member provided on each of the side walls along the stacking direction of the fuel cells 51, and is fastened to the end plate 53a and the end plate 53b. Thereby, a predetermined surface pressure is generated in each fuel cell 51.

  Next, details of the fuel cell 51 and the external restraint member 60 will be described. FIG. 2 is a partially enlarged cross-sectional view of the fuel battery cell 51 and the external restraint member 60. As shown in FIG. 2, the fuel cell 51 has a structure in which a seal gasket-integrated MEA (membrane electrode assembly) 20 is sandwiched between two separators 10. The separator 10 has a structure in which an intermediate plate 12 is sandwiched between a cathode facing plate 11 and an anode facing plate 13. These three plates constituting the separator 10 are joined by hot pressing or the like.

  The seal gasket-integrated MEA 20 includes an MEA 21 and a seal gasket 22. The MEA 21 includes a power generation unit 24 having a catalyst layer formed on both surfaces of an electrolyte membrane having proton conductivity, a gas diffusion layer 23 formed under the power generation unit 24, and a gas diffusion layer 25 formed on the power generation unit 24. . In this embodiment, the upper surface side of the MEA 21 functions as an anode, and the lower surface side of the MEA 21 functions as a cathode.

  Further, the seal gasket 22 is provided with a cut 26 extending from the end surface on the external restraining member 60 side toward the MEA 21 side. The external restraint member 60 is made of a rigid body such as stainless steel. An insulating member is formed on the surface of the external restraint member 60 on the fuel cell 51 side. Thereby, the short circuit of the fuel cell 51 is prevented. A protruding member 61 is provided on the fuel cell 51 side of the external restraining member 60. The protruding member 61 has a tapered shape in which the width in the stacking direction increases from the tip on the fuel cell 51 side to the external restraint member 60 side. The tip of the protruding member 61 on the fuel cell 51 side faces the cut 26.

  FIG. 3 is a diagram for explaining the details of the separator 10 and the seal gasket-integrated MEA 20. 3A is a schematic plan view of the cathode facing plate 11, FIG. 3B is a schematic plan view of the anode facing plate 13, and FIG. 3C is a schematic plan view of the intermediate plate 12. FIG. 3D is a schematic plan view of the seal gasket-integrated MEA 20.

  The cathode facing plate 11 is a rectangular metal plate. As the metal plate, a plate made of titanium, titanium alloy, stainless steel, or the like that has been subjected to plating treatment for corrosion prevention can be used. The cathode facing plate 11 has a thickness of about 0.15 mm, for example.

  As shown in FIG. 3A, a portion of the cathode facing plate 11 facing the MEA 21 (hereinafter referred to as a power generation region X) is a plane. A fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, a cooling medium supply manifold 43a, and a cooling medium discharge manifold 43b are formed on the outer peripheral edge of the cathode facing plate 11. Has been. The cathode facing plate 11 has a plurality of oxidant gas supply holes 44a and a plurality of oxidant gas discharge holes 44b. The manifolds and the holes penetrate the cathode facing plate 11 in the thickness direction.

  The anode facing plate 13 is a rectangular metal plate having substantially the same shape as the cathode facing plate 11 and is made of the same material as the cathode facing plate 11. The anode facing plate 13 has a thickness of 0.15 mm, for example. The power generation region X in the anode facing plate 13 is a plane.

  Similar to the cathode facing plate 11, on the outer peripheral edge of the anode facing plate 13, there are a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, and a cooling medium supply manifold 43a. In addition, a cooling medium discharge manifold 43b is formed. The anode facing plate 13 has a plurality of fuel gas supply holes 45a and a plurality of fuel gas discharge holes 45b. The manifolds and the holes penetrate the anode facing plate 13 in the thickness direction.

  The intermediate plate 12 is a rectangular metal plate having the same shape as the cathode facing plate 11 and is made of the same material as the cathode facing plate 11. The intermediate plate 12 has a thickness of 0.35 mm, for example. Similar to the cathode facing plate 11, a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, and an oxidant gas discharge manifold 42b are formed on the outer peripheral edge of the intermediate plate 12.

  Further, the intermediate plate 12 is formed with a plurality of fuel gas supply passages 46a having one end communicating with the fuel gas supply manifold 41a and the other end communicating with the fuel gas supply hole 45a. Similarly, the intermediate plate 12 is formed with a plurality of fuel gas discharge passages 46b having one end communicating with the fuel gas discharge manifold 41b and the other end communicating with the fuel gas discharge hole 45b.

  Further, the intermediate plate 12 is formed with a plurality of fuel gas supply passages 46a having one end communicating with the oxidant gas supply manifold 42a and the other end communicating with the oxidant gas supply hole 44a. Similarly, the intermediate plate 12 is formed with a plurality of oxidant gas discharge passages 47b having one end communicating with the oxidant gas discharge manifold 42b and the other end communicating with the oxidant gas discharge hole 44b. Further, the intermediate plate 12 is formed with a plurality of cooling medium flow paths 48 having one end communicating with the cooling medium supply manifold 43a and the other end communicating with the cooling medium discharge manifold 43b. Each flow path penetrates the intermediate plate 12 in the thickness direction.

  As shown in FIG. 3 (d), the seal gasket-integrated MEA 20 has a structure in which a seal gasket 22 is joined to the outer peripheral edge of the MEA 21. The seal gasket 22 is made of a resin material such as silicon rubber, butyl rubber, or fluorine rubber, for example. The seal gasket 22 is manufactured by injection-molding the resin material with the outer peripheral end of the MEA 21 facing the mold cavity. According to this method, the MEA 21 and the seal gasket 22 are joined without a gap. Thereby, leakage from the junction of the cooling medium, the oxidant gas, and the fuel gas can be prevented.

  Similar to the cathode facing plate 11, the seal gasket 22 includes a fuel gas supply manifold 41a, a fuel gas discharge manifold 41b, an oxidant gas supply manifold 42a, an oxidant gas discharge manifold 42b, a cooling medium supply manifold 43a, and a cooling medium discharge manifold. 43b is formed. The seal gasket 22 seals the two separators 10 in contact with the upper surface and the lower surface. The seal gasket 22 seals between the outer periphery of the MEA 21 and the outer periphery of each manifold. In FIG. 3 (d), a seal line SL connecting the contact portions between the seal gasket 22 and the separator 10 is shown to make the drawing easier to see.

  Next, an outline of the operation of the fuel cell 100 during power generation will be described. First, a fuel gas containing hydrogen is supplied to the fuel gas supply manifold 41a. This fuel gas is supplied to the gas diffusion layer 25 on the anode side of the MEA 21 via the fuel gas supply channel 46a. Hydrogen in the fuel gas is converted into protons in the catalyst layer of the power generation unit 21. The converted protons are conducted through the electrolyte membrane of the power generation unit 21 and reach the catalyst layer on the cathode side.

  On the other hand, an oxidizing gas containing oxygen is supplied to the oxidizing gas supply manifold 42a. The oxidant gas is supplied to the catalyst layer on the cathode side of the power generation unit 21 via the oxidant gas supply channel 47 a and the gas diffusion layer 23 on the cathode side of the MEA 21. Thereafter, water is generated and electric power is generated from oxygen in the oxidant gas and protons that have reached the catalyst layer on the cathode side. The generated electric power is collected through the separator 10.

  A cooling medium such as cooling water is supplied to the cooling medium supply manifold 43a. This cooling medium flows through the cooling medium flow path 48 to cool the fuel cell 100. Thereby, the temperature of the fuel cell 100 can be adjusted to an appropriate temperature. The cooling medium flowing through the cooling medium flow path 48 is discharged to the outside through the cooling medium discharge manifold 43b. The fuel gas that has not been used for power generation is discharged to the outside through the fuel gas discharge passage 46b and the fuel gas discharge manifold 41b. Further, the oxidant gas that has not been used for power generation is discharged to the outside through the oxidant gas discharge passage 47b and the oxidant gas discharge manifold 42b.

  Next, the operation of the fuel cell 100 when the gas pressure in the manifold increases will be described. FIG. 4 is a diagram showing the operation of the fuel cell 100 when the gas pressure in the manifold increases. As shown in FIG. 4, when the gas pressure in the manifold increases, the outer peripheral portion of the seal gasket 22 tends to protrude toward the external restraint member 60 side. Thereby, the protruding member 61 is inserted into the cut 26. In this case, since the width of the protruding member 61 increases from the tip on the fuel cell 51 side to the external restraint member 60 side, the protruding member 61 serves as a stopper for the seal gasket 22. Therefore, the protrusion of the outer peripheral portion of the seal gasket 22 can be prevented.

  In addition, the protruding member 61 attempts to spread the seal gasket 22 in the stacking direction of the stacked body 50 when the seal gasket 22 is about to move to the external restraint member 60 side. That is, the load generated between the protruding member 61 and the seal gasket 22 is converted into the stacking direction of the fuel cells 51 and applied to the seal gasket 22. Thereby, the seal load between the seal gasket 22 and the separator 10 increases. As a result, gas leakage from the seal gasket 22 can be prevented.

  The protruding member 61 may be a rigid body such as stainless steel having an insulating film formed on the surface thereof, or may be rubber or the like constituting the seal gasket 22. When rubber is used as the protruding member 61, it is preferable that the rubber constituting the protruding member 61 has a higher hardness than the rubber forming the seal gasket 22. This is because the load direction conversion function of the protruding member 61 is enhanced.

  Here, it is difficult to prevent the seal gasket 22 from protruding as described above by the fastening load of the fuel cell 100. This is because the fastening load direction of the fuel cell 100 and the protruding direction of the seal gasket 22 are substantially perpendicular. Therefore, the present invention is very effective for the sticking out of the seal gasket 22.

(Modification)
FIG. 5 is a diagram for explaining a protrusion member 61 a which is a modification of the protrusion member 61. The tip of the protruding member 61a on the fuel cell 51 side has a spherical shape. In this case, the protruding member 61 a tries to spread the seal gasket 22 in the stacking direction of the fuel cells 51 when the seal gasket 22 is about to move toward the external restraint member 60. That is, the load generated between the protruding member 61 a and the seal gasket 22 is converted into the stacking direction of the fuel cells 51 and applied to the seal gasket 22.

  An insertion member 61b inserted into the cut 26 may be provided instead of the protruding members 61 and 61a as described above. FIG. 6 is a diagram for explaining the insertion member 61b. The insertion member 61 b is provided not in the external restraining member 60 but in the cut 26 of the seal gasket 22. The upper surface of the insertion member 61b is connected to the lower surface of the cut 26 by an elastic member, and the lower surface of the insertion member 61b is connected to the upper surface of the cut 26 by an elastic member. Accordingly, the insertion member 61b can move in the cut 26 in a direction substantially perpendicular to the stacking direction. The insertion member 61b is made of the same material as the seal gasket 22.

  In this case, when the insertion member 61 b is pressed against the external restraint member 60 as the seal gasket 22 moves toward the external restraint member 60, the insert member 61 b tends to spread the seal gasket 22 in the stacking direction of the fuel cells 51. . That is, a load generated between the external restraining member 60 and the seal gasket 22 is converted into the stacking direction of the fuel cells 51 and applied to the seal gasket 22.

  Further, the insertion member 61b and the cut 26 can be easily aligned as compared with the case where the protruding members 61 and 61a are provided. Furthermore, it is not necessary to consider the positional change of the cuts 26 in the stacking direction due to thermal expansion or the like. The seal gasket 22 and the insertion member 61b can be manufactured by injection molding or the like. The insertion member 61b may have a tapered shape in which the width in the stacking direction increases from the tip on the fuel cell 51 side to the external restraint member 60 side, and the shape at the tip on the fuel cell 51 side is spherical. It may be a shape.

  Thus, the arrangement location and shape of the protrusion member or the insertion member provided in the fuel cell 100 are not particularly limited. The projecting member or the insertion member may be disposed at any location and shape as long as it converts the load generated between the seal gasket 22 and the external restraint member 60 in the stacking direction of the fuel cells 51. .

  In this embodiment, the seal gasket integrated type 20 corresponds to the seal gasket integrated membrane electrode assembly, and the combination of the cut 26 and the protruding members 61 and 61a or the combination of the cut 26 and the insertion member 61b is the load direction. It corresponds to the conversion means.

  Subsequently, a fuel cell 100a according to a second embodiment of the present invention will be described. The fuel cell 100a differs from the fuel cell 100 of FIG. 1 in that an external restraint member 60a is provided instead of the external restraint member 60. The external restraining member 60a is made of an elastic sheet having insulation properties, and is made of a sheet such as rubber, for example. The external restraint member 60a is provided so as to cover the entire side wall along the stacking direction of the fuel cells 100, similarly to the external restraint member 60 of FIG. A plurality of protruding members 62 having the same shape as the protruding member 61 of the first embodiment are formed on the external restraining member 60a. The protruding member 62 is made of an elastic member such as rubber having a hardness higher than that of the rubber constituting the seal gasket 22.

  FIG. 7 is a partially enlarged cross-sectional view of the fuel battery cell 51 and the external restraint member 60a. In the present embodiment, since the external restraint member 60 a is made of an elastic sheet, the external restraint member 60 a applies a certain load to each fuel cell 51. Further, the external restraining member 60 a is deformed according to the position of each fuel cell 51. Thereby, the external restraint member 60a can suppress a rapid load fluctuation in the fuel cell 100a due to an external force or the like.

  Further, when the position of the seal gasket-integrated MEA 20 is shifted to the external restraint member 60 a side, the protruding member 62 is inserted into the cut 26. In this case, the load generated between the protruding member 62 and the seal gasket 22 is converted into the stacking direction of the fuel cells 51 and applied to the seal gasket 22. Thereby, gas leakage from the seal gasket 22 can be prevented.

  Instead of the protruding member 62, an insertion member as shown in FIG. In this embodiment, the seal gasket integrated type 20 corresponds to a seal gasket integrated type membrane electrode assembly, and the notch 26 and the protruding member 62 correspond to load direction changing means.

It is sectional drawing which shows the outline of the fuel cell which concerns on 1st Example of this invention. It is a partial expanded sectional view of a fuel cell and an external restraint member. It is a figure for demonstrating the detail of a separator and seal gasket integrated MEA. It is a figure which shows operation | movement of a fuel cell when the gas pressure in a manifold increases. It is a figure for explaining the modification of a projection member. It is a figure for demonstrating an insertion member. It is a partial expanded sectional view of the fuel cell and external restraint member concerning the 2nd example.

Explanation of symbols

10 Separator 20 Seal gasket integrated MEA
22 Seal gasket 26 Cut 50 Stack 51 Fuel cell 60 External restraint member 61, 61a, 62 Projection member 61b Insertion member 100, 100a Fuel cell

Claims (10)

A laminate in which a seal gasket-integrated membrane electrode assembly including a seal gasket and separators are alternately laminated;
An external restraining member disposed on a side wall along the laminating direction of the laminate,
A fuel cell comprising load direction conversion means for converting a load applied between the external restraining member and the seal gasket into a stacking direction in the stacked body. The load direction conversion means includes a projecting member provided on the seal gasket side of the external restraining member, and a notch formed on the seal gasket and facing the projecting member. 1. The fuel cell according to 1. 3. The fuel cell according to claim 2, wherein the protruding member has a tapered shape whose width increases from the seal gasket side to the external restraint member side. The fuel cell according to claim 2, wherein a tip portion of the protruding member on the seal gasket side is spherical. 2. The fuel according to claim 1, wherein the load direction changing means is composed of a cut provided on an end surface of the seal gasket on the side of the external restraint member and an insertion member inserted into the cut. battery. The fuel cell according to claim 5, wherein the insertion member has a tapered shape whose width increases toward the external restraint member. 6. The fuel cell according to claim 5, wherein a tip portion of the insertion member on the seal gasket side is spherical. The fuel cell according to claim 1, wherein the seal gasket is formed with a manifold for allowing fluid to flow. The external restraining member is composed of a rigid body,
The fuel cell according to claim 1, wherein at least a surface of the external restraining member on the seal gasket side is made of an insulator. The fuel cell according to claim 1, wherein the external restraining member is made of an elastic body having an insulating property.

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