JP2005183221A - Fuel cell sealing structure and sealing method - Google Patents

Abstract

To improve the sealing performance of a fuel cell.
SOLUTION: A fuel cell is configured by sandwiching the outer side of a membrane electrode assembly in which a solid polymer electrolyte membrane 1 is sandwiched between a pair of electrodes 3 and 5 between a pair of separators 7 and 9. The solid polymer electrolyte membrane 1 is provided with a protruding portion 1 a that protrudes from the outer peripheral edge portions 3 a and 5 a of the electrodes 3 and 5, and a separator support portion 11 is provided between the protruding portion 1 a and the separators 7 and 9. Three rows of convex portions 13 are provided on the surface of the separator support portion 11 facing the separator 7 so as to be parallel to each other along the outer peripheral edge portions 3a and 5a of the electrodes 3 and 5. The convex portion 13 has a triangular cross-sectional shape that becomes narrower from the base end portion toward the distal end portion. The concave portion 15 that has a shape corresponding to the convex portion 13 and fits with the convex portion 13 is formed in each separator 7. , 9 respectively.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell sealing structure and a sealing method in which a further outer side of a membrane electrode assembly in which a solid electrolyte membrane is sandwiched between a pair of electrodes is sandwiched between a pair of separators.

  A fuel cell is a device that converts the chemical energy of fuel directly into electrical energy by electrochemically reacting a fuel gas such as a hydrogen-containing gas that is a reactive gas with an oxidant gas such as air. It has excellent characteristics such as high energy efficiency compared to other energy engines and no generation of exhaust gas because there is no need to use fossil fuels that have a problem of resource depletion.

  As such a fuel cell, for example, in a polymer electrolyte fuel cell, a solid polymer electrolyte membrane is sandwiched between a pair of electrodes, used to collect electricity from the electrodes in contact with the electrodes, and for supplying gas to the electrode side. A separator having a gas flow path and a cooling water flow path on the opposite side of the electrode is provided.

As a sealing structure in such a polymer electrolyte fuel cell, for example, there is one described in Patent Document 1 below. In this publication, after applying a liquid seal to the groove portion of the separator corresponding to the protruding portion of the solid polymer electrolyte membrane protruding from the electrode, this is sandwiched between a pair of separators and temporarily assembled. The solid fuel seal is solidified to obtain a unit fuel cell.
JP 2002-246044 A

  However, in the above-described conventional fuel cell seal structure, the seal pressure varies depending on the amount of liquid seal applied. For example, if the amount of liquid seal is too small, the sealing pressure is insufficient and sufficient sealing cannot be performed, and if the amount of liquid seal is too large, the surface pressure between the separator and the electrode is insufficient and the electrical resistance increases. , Causing a decrease in battery performance. For this reason, the conventional sealing structure has insufficient sealing performance.

  Accordingly, an object of the present invention is to improve the sealing performance of a fuel cell.

  In the present invention, a fuel cell is configured by sandwiching a further outer side of a membrane electrode assembly in which a solid electrolyte membrane is sandwiched between a pair of electrodes with a pair of separators, and the solid electrolyte membrane protrudes from an outer peripheral edge portion of the electrodes. A protruding portion is provided, a separator support portion is provided between the protruding portion and the separator, a convex portion is provided on a surface of the separator supporting portion facing the separator, and a concave portion that fits with the convex portion is formed in the concave portion. The main feature is that the separator is provided.

  According to the present invention, the separator support portion is provided between the protruding portion of the solid electrolyte membrane that protrudes from the outer peripheral edge portion of the electrode and the separator, and the convex portion provided in the separator support portion and the concave portion provided in the separator are fitted. Since the mating structure is adopted, the sealing performance can be improved by preventing a change in the sealing pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view in which a part of a fuel cell showing the first embodiment of the present invention is omitted. This fuel cell is a polymer electrolyte fuel cell, and a membrane electrode assembly is constituted by sandwiching a polymer electrolyte membrane 1 from a pair of electrodes 3 and 5 from both sides, and a pair of electrodes outside the membrane electrode assembly. The structure is sandwiched between the separators 7 and 9.

  Usually, in order to obtain a predetermined power, a fuel cell is used as a fuel cell stack by laminating a set of unit fuel cells composed of the above-described membrane electrode assembly and a pair of separators 7 and 9.

  The separators 7 and 9 include gas supply gas flow paths 7 a and 9 a on the electrodes 3 and 5 side, respectively, and a cooling water flow path 9 b on the side opposite to the electrode 5 of one separator 9. Hydrogen serving as a fuel is supplied to the gas flow path 9 a of the one separator 9, and air serving as an oxidant is supplied to the gas flow path 7 a of the other separator 7.

  The solid polymer electrolyte membrane 1 is provided with a protruding portion 1a protruding from the outer peripheral edge portions 3a and 5a of the electrodes 3 and 5 over the entire circumference of the electrodes 3 and 5, and between the protruding portion 1a and the separators 7 and 9. In addition, a separator support portion 11 is provided. That is, the separator support portion 11 is also provided over the entire circumference along the outer peripheral edge portions 3a and 5a of the electrodes 3 and 5.

  On the surface of the separator support portion 11 facing the separator 7, three rows of convex portions 13 are provided in parallel with each other along the outer peripheral edge portions 3 a and 5 a of the electrodes 3 and 5. The convex portion 13 has a triangular cross-sectional shape that becomes thinner as it goes from the base end portion toward the distal end portion. The concave portion 15 that has a shape corresponding to the convex portion 13 and fits with the convex portion 13 is formed in each of the concave portions 15. The separators 7 and 9 are provided respectively.

  Also, the separators 7 and 9 in the vicinity of the outer peripheral edge portions 3a and 5a of the electrodes 3 and 5 are provided with a butting portion 17 having a flat tip, and the abutting portion 17 is brought into contact with the separator support portion 11.

  In the sealing structure described above, sealing is performed by fitting the convex portions 13 of the separator support portion 11 into the concave portions 15 of the separators 7 and 9. At this time, since the inclined surface 13a of the convex portion and the inclined surface 15a of the concave portion 15 are brought into close contact with each other to form a seal alignment surface, the area of the seal alignment surface can be widened efficiently. Furthermore, by providing a plurality of combinations of the convex portion 13 and the concave portion 15, the area of the seal mating surface can be further increased, and the sealing performance can be efficiently secured.

  Further, since the abutting portion 17 of the separators 7 and 9 abuts on the separator support portion 11, the clearance management of the seal surface can be performed, which can contribute to the improvement of the sealing performance.

  Therefore, according to the above-described seal structure, it is not necessary to apply a liquid seal as in the prior art, so that the seal performance can be improved while preventing a change in the seal pressure. Moreover, since it is the fitting structure of the convex part 13 and the recessed part 15, mutual positioning can be performed and assembly workability | operativity improves.

  In the above sealing structure, the surfaces of the separators 7 and 9 facing the convex portions 17 of the separator support portion 11 are made flat without providing the concave portions 15, and the convex portions 13 are bited into the flat surfaces during assembly. A recess may be formed. In this case, if the separators 7 and 9 are made of a metal such as an aluminum alloy, it is effective because cracks do not occur even if they are bitten.

  FIG. 2 is a cross-sectional view showing a part of the fuel cell according to the second embodiment of the present invention before assembly. In this embodiment, the separator support part 11 is provided with a convex part 19 having an R shape at the tip, and the separators 7 and 9 are provided with a concave part 21 having an R shape at the bottom correspondingly. Then, a liquid sealant 23 is applied onto the separator support portion 11 during assembly, thereby providing a seal material between the separator support portion 11 and the separators 7 and 9. As the liquid sealant, an epoxy or olefin resin is used.

  Here, the R portion 19a at the tip of the convex portion 19 has a larger radius of curvature than the R portion 21a of the concave portion 21, and the R portion 19a of the convex portion 19 and the concave portion 21 of the concave portion 21 are shown in FIG. A space is formed between the R portion 21a and the liquid sealant 23 enters the space. At this time, the inclined surface 19b of the convex portion 19 and the inclined surface 21b of the concave portion 21 are in close contact with each other.

  According to the second embodiment described above, since the liquid sealing agent 23 is provided between the convex portion 19 and the concave portion 21, the sealing performance is further improved.

  FIG. 4 is a cross-sectional view showing a part of the fuel cell according to the third embodiment before assembly. In this embodiment, convex portions 13 and concave portions 15 having the same shapes as those in the first embodiment shown in FIG. 1 are provided in the separator support portion 11 and the separator 7 (9), respectively. 15, a sheet-like sealing material 25 is provided between the separator support portion 11 and the separator 7 (9).

  When assembled in a state where the sheet-like sealing material 25 is placed on the separator support portion 11 as shown in FIG. 4, the separator support portion 11 including the convex portion 13 and the concave portion 15 as shown in FIG. The sealing material 25 is sandwiched between the separator 7 (9) and exhibits a sealing function.

  Also in the third embodiment, since the sealing material 25 is provided between the convex portion 13 and the concave portion 15 as in the second embodiment, the sealing performance is further improved. Further, in this example, by using a silicon-based resin as the sealing material 25, the sealing material 25 enters between the convex portion 13 and the concave portion 15 with good followability, and the assembling work becomes easy.

  According to the present invention, the convex portion of the separator support portion has a triangular cross-sectional shape that becomes thinner from the base end portion toward the distal end portion, and the concave portion corresponds to the shape of the convex portion. Can be increased, the assembly work can be facilitated, and the positioning accuracy is improved.

  Since the concave portion of the separator is formed by causing the convex portion of the separator support portion to bite into the flat surface of the separator, there is no need to provide the concave portion in the separator in advance, and in this case, the separator is made of metal. In some cases, cracking is effective because no cracks occur.

  Moreover, since the sealing material is provided between the convex portion and the concave portion, the sealing performance is further improved.

  Since the tip of the convex portion has an R shape and the bottom of the concave portion has an R shape corresponding thereto, and a liquid sealant is provided between the convex portion and the concave portion, the sealing performance is further improved.

  Since a sheet-like sealing material is provided between the separator support part and the separator so as to cover the convex part and the concave part, the sealing performance is further improved.

  Since a plurality of combinations of the convex portion and the concave portion are provided between the inner peripheral side and the outer peripheral side where the outer peripheral edge portion of the electrode is located, the area of the seal mating surface can be increased efficiently and the sealing performance can be increased. Further improvement can be achieved.

  The separator is provided with an abutting part that abuts against the inner peripheral part of the separator support part, so that the abutment part abuts on the separator support part, so that the clearance of the seal surface can be managed and the sealing performance is improved. Can contribute.

It is sectional drawing which abbreviate | omitted a part of fuel cell concerning the 1st Embodiment of this invention. It is sectional drawing which shows a part before the assembly of the fuel cell concerning the 2nd Embodiment of this invention. It is sectional drawing of the principal part after the assembly in 2nd Embodiment. It is sectional drawing which shows a part before the assembly of the fuel cell concerning the 3rd Embodiment of this invention. It is sectional drawing of the principal part after the assembly in 3rd Embodiment.

Explanation of symbols

1 Solid polymer electrolyte membrane (solid electrolyte membrane, membrane electrode assembly)
1a Protruding part 3, 5 electrode (membrane electrode assembly)
3a, 5a Electrode outer peripheral edge portion 7, 9 Separator 11 Separator support portion 13, 19 Protrusion portion 15, 21 Concavity portion 17 Abutting portion 23 Liquid sealant 25 Sheet-like sealing material

Claims (9)

  A fuel cell is constructed by sandwiching the outer side of the membrane electrode assembly, in which the solid electrolyte membrane is sandwiched between a pair of electrodes, with a pair of separators, and the solid electrolyte membrane is provided with a protruding portion protruding from the outer peripheral edge of the electrode. The separator support part is provided between the protruding part and the separator, the convex part is provided on the surface of the separator support part facing the separator, and the concave part that fits the convex part is provided in the separator. A fuel cell seal structure.   2. The fuel cell seal according to claim 1, wherein the convex portion has a triangular cross-sectional shape that becomes narrower from the proximal end portion toward the distal end portion, and the concave portion corresponds to the shape of the convex portion. Construction.   3. The fuel cell seal structure according to claim 2, wherein the concave portion is formed by causing the convex portion to bite into a flat surface of the separator.   The fuel cell sealing structure according to claim 1, wherein a sealing material is provided between the convex portion and the concave portion.   The tip of the convex part is formed into an R shape, and the bottom of the concave part is formed into an R shape correspondingly, and a liquid sealant is provided between the convex part and the concave part. Fuel cell seal structure.   5. The fuel cell sealing structure according to claim 4, wherein a sheet-like sealing material is provided between the separator support part and the separator so as to cover the convex part and the concave part.   The fuel cell according to any one of claims 1 to 6, wherein a plurality of combinations of the convex portion and the concave portion are provided between an inner peripheral side and an outer peripheral side where the outer peripheral edge portion of the electrode is located. Seal structure.   8. The fuel cell seal structure according to claim 1, wherein the separator is provided with an abutting portion that abuts against the separator support portion at an inner peripheral side of the convex portion. 9.   A fuel cell is constructed by sandwiching the outer side of the membrane electrode assembly, in which the solid electrolyte membrane is sandwiched between a pair of electrodes, with a pair of separators, and the solid electrolyte membrane is provided with a protruding portion protruding from the outer peripheral edge of the electrode. A separator support portion is provided between the protruding portion and the separator, and the convex portion provided on the surface of the separator support portion facing the separator is fitted into the concave portion provided in the separator for sealing. A fuel cell sealing method characterized by the above.

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