JP6520666B2 - Fuel cell seal structure - Google Patents

Description

  The present invention relates to a fuel cell seal structure.

  Generally, a fuel cell has a stack structure in which a plurality of single cells are stacked. Each single cell has a membrane electrode assembly and two separators sandwiching the membrane electrode assembly. The separator is formed with a reaction gas flow path for flowing a reaction gas into the single cell and a cooling medium flow path for flowing a cooling medium into the single cell. Further, the separator is formed with a reaction gas manifold that functions as an inlet and an outlet of the reaction gas, and a cooling medium manifold that functions as an inlet and an outlet of the cooling medium channel. Seal members (gaskets) for suppressing leakage of the respective fluids are appropriately provided around the reaction gas flow channel, the cooling medium flow channel, the reaction gas manifold, and the cooling medium manifold. In addition, the shape of the seal member is devised to secure the sealability. For example, according to Patent Document 1, a seal structure in which a seal intersection where an increase in local linear pressure is caused when the seal member is compressed is formed of a material having a lower elastic modulus than other linear seals. Is disclosed. With this seal structure, application of excessive linear pressure to the seal intersection portion can be suppressed, and a decrease in seal performance can be prevented.

JP, 2013-145713, A

  Here, the inventor of the present invention found that the sealability of the seal member provided at the position (specific corner portion) corresponding to the corner portion of the separator among the seal members provided at the corner portion of the manifold is insufficient. I found that it could be. Specifically, when an internal pressure is applied to the seal member surrounding the periphery of the manifold, the seal member disposed at a specific corner of the manifold expands outward to reduce the thickness, and the linear pressure decreases. , I found a problem that the sealability may be reduced.

  The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following modes.

(1) According to one aspect of the present invention, a fuel cell seal structure is provided. The fuel cell seal structure is disposed between unit cells of the fuel cell, and is provided so as to surround the manifold of the unit cell separator. The seal structure includes: a central seal that seals between the unit cells; and a peripheral seal that is integrally formed with the central seal on both sides of the central seal and that is thinner than the central seal. Prepare. Among the corner portions of the manifold, the width of the peripheral seal portion disposed at the specific corner portion located at the corner portion of the separator is larger than the width of the peripheral seal portion disposed at the linear portion of the manifold while being the width of the central sealing portion arranged in a particular corner portion is configured to the same the width of the central sealing portion arranged in the linear portion of the manifold.

  According to the seal structure of this aspect, when an internal pressure is applied to the seal structure in a state where a plurality of unit cells are stacked, the seal member disposed at a specific corner of the manifold is unlikely to expand outward, and local elongation The linear pressure drop is suppressed. At the same time, the leakage of gas from the connection portion between the seal member at the specific corner of the manifold and the seal member at the straight portion of the manifold is prevented, and sufficient sealing performance can be ensured.

  The present invention can also be realized in various forms other than the above-described seal structure. For example, the present invention can be realized in the form of a fuel cell separator provided with the seal structure of the above embodiment, a single cell of a fuel cell provided with the separator, a fuel cell provided with the single cell, a fuel cell system provided with the fuel cell, and the like.

It is an explanatory view showing a schematic structure of a fuel cell system in a 1st embodiment of the present invention. It is the schematic plan view which looked at the anode side separator of the single cell from the opposite side to MEA. It is a schematic plan view which expands and shows oxygen gas outlet manifold vicinity in a 1st embodiment. It is an explanatory view showing the section of the seal structure which surrounds the oxidant gas outlet manifold in a 1st embodiment. It is a schematic plan view which expands and shows oxygen gas outlet manifold vicinity in a 2nd embodiment. It is a schematic plan view which expands and shows oxygen gas outlet manifold vicinity in a 3rd embodiment. It is explanatory drawing which shows the cross section of the seal structure which encloses the oxidant gas outlet manifold in 3rd Embodiment.

A. First embodiment:
FIG. 1 is an explanatory view showing a schematic configuration of a fuel cell system 10 according to a first embodiment of the present invention. The fuel cell system 10 includes a fuel cell stack 100. In the fuel cell stack 100, an end plate 110, an insulating plate 120, a current collector plate 130, a plurality of unit cells 140, a current collector plate 130, an insulating plate 120, and an end plate 110 are stacked in this order. Have a stacked structure. The stacking direction of the single cells 140 is a direction X perpendicular to the vertical direction Y.

  Hydrogen as a fuel gas is supplied to the fuel cell stack 100 from a hydrogen tank 150 storing high pressure hydrogen via a shut valve 151, a regulator 152, and a pipe 153. The fuel gas (anode off gas) not used in the fuel cell stack 100 is discharged to the outside of the fuel cell stack 100 through the discharge pipe 163. The fuel cell system 10 may have a recirculation mechanism that recirculates the anode off gas to the pipe 153 side. The fuel cell stack 100 is also supplied with air as an oxidant gas via an air pump 160 and a pipe 161. The oxidant gas (cathode off gas) not used in the fuel cell stack 100 is discharged to the outside of the fuel cell stack 100 via the discharge pipe 154. The fuel gas and the oxidant gas are also called reactive gases.

  Furthermore, to cool the fuel cell stack 100, the cooling medium cooled by the radiator 170 is supplied to the fuel cell stack 100 via the water pump 171 and the pipe 172. The cooling medium discharged from the fuel cell stack 100 is circulated to the radiator 170 via the pipe 173. As the cooling medium, for example, water, antifreeze water such as ethylene glycol, air or the like is used. In the present example, water (also referred to as "cooling water") is used as the cooling medium.

  The unit cell 140 provided in the fuel cell stack 100 has a membrane electrode assembly (also called MEA) 30 in which an anode and a cathode are disposed on both sides of an electrolyte membrane, respectively. It is configured to be held by the separator 40. The anode side separator 50 is provided with a plurality of streaked fuel gas flow grooves 52 on the surface on the MEA 30 side, and a plurality of streaks of cooling medium flow grooves 54 on the surface opposite to the MEA 30. The cathode side separator 40 is provided with a plurality of streaky oxidant gas flow grooves 42 on the surface on the MEA 30 side. A sealing member 32 made of an insulating resin is provided on the outer periphery of the MEA 30 sandwiched by the anode side separator 50 and the cathode side separator 40.

  FIG. 2 is a schematic plan view of the anode side separator 50 of the unit cell 140 as viewed from the side opposite to the MEA 30. In FIG. 2, the front and back direction is the stacking direction X, and the vertical direction is the vertical direction Y. The horizontal direction in the figure perpendicular to the vertical direction Y and the stacking direction X is the horizontal direction Z. The anode side separator 50 and the cathode side separator 40 are made of a member having a gas barrier property and an electron conductivity, and for example, a carbon member such as dense carbon or the like in which carbon particles are compressed to be gas impermeable, It is formed of a metal member such as press-formed stainless steel or titanium steel. In the present embodiment, the separators 40 and 50 are metal press separators.

  The fuel gas inlet communication manifold 62, the cooling medium outlet manifold 84, and the oxidant gas inlet communication manifold 72 are arranged in order from the top along the vertical direction Y at one end of the anode separator 50 in the horizontal direction Z. It is done. On the other hand, at the other end edge, the oxidant gas outlet manifold 74, the cooling medium inlet communication manifold 82, and the fuel gas outlet manifold 64 are arranged in order from the top along the vertical direction Y, There is. The fuel gas inlet communication manifold 62 and the fuel gas outlet manifold 64, the oxidant gas inlet communication manifold 72 and the oxidant gas outlet manifold 74, the coolant inlet communication manifold 82 and the coolant outlet manifold 84 are both sides of the horizontal direction Z The outer edge portions are arranged to face each other.

  The fuel gas supplied from the fuel gas inlet manifold (not shown) of the cathode side separator 40 is distributed to the fuel gas flow channel 52 (FIG. 1) of the unit cell 140, and the fuel gas flow is carried out by the fuel gas outlet manifold 64. The fuel gas not utilized in the passage groove 52 is collected and supplied to the adjacent single cell fuel gas inlet manifold. Further, after the oxidant gas supplied from the oxidant gas inlet manifold (not shown) of the cathode side separator 40 is distributed to the oxidant gas flow channel 42 (FIG. 1) of the unit cell 140, the oxidant gas outlet The manifold 74 collects oxidant gas that has not been utilized in the oxidant gas flow channel 42 and supplies it to the oxidant gas inlet manifold of the next adjacent single cell. Further, the cooling medium supplied from the cooling medium inlet manifold (not shown) of the cathode side separator 40 is diffused through one end provided with the dimple 56 of the anode side separator 50 and flows through the cooling medium flow channel 54. The coolant is collected by the coolant outlet manifold 84 from the coolant channel groove 54 through the other end provided with the dimples 56 and supplied to the coolant inlet manifold of the next adjacent single cell. Further, the cooling medium inlet communication manifold 82, the cooling medium channel groove 54, and the cooling medium outlet manifold 84 communicate with each other in the horizontal direction Z in a plane viewed from the side opposite to the MEA 30 of the anode side separator 50. The cooling medium flow channel surface 200 is configured. Each of the manifolds 62, 64, 72, 74, 82, 84 has a substantially rectangular opening. Each manifold has a shape extending in the stacking direction X of the fuel cell stack 100.

  Seal structures SL1 to SL5 (also referred to as “gaskets”) surrounding the reaction gas manifolds 62, 64, 72, 74 and the cooling medium flow channel surface 200, respectively, in the plane of the anode side separator 50 seen from the opposite side to the MEA 30. It is formed. The seal structures SL1 to SL5 have a function of coming into contact with the surface of another adjacent single cell 140 and sealing between the two single cells 140 when the plurality of single cells 140 are stacked. Specifically, seal structures SL1 and SL2 are for suppressing the leakage of fuel gas, seal structures SL3 and SL4 are for suppressing the leakage of oxidant gas, and seal structure SL5 is a cooling medium. To prevent the leakage of These seal structures SL1 to SL5 are formed by injection molding, press molding or the like, and have a central seal portion m and a peripheral seal portion r (FIG. 3). Rubber, a thermoplastic elastomer, etc. can be used as a material of seal structure SL1-SL5. The seal structures SL1 to SL5 are fixed by being bonded to the separator by an adhesive. A groove 80 is formed in a region where the seal structures SL1 to SL5 are arranged (a part of a plane viewed from the side opposite to the MEA 30 of the anode side separator 50).

  FIG. 3 is a schematic plan view showing the vicinity of the oxidant gas outlet manifold 74 of the anode side separator 50 shown in FIG. 2 in an enlarged manner. The seal structure SL4 surrounding the oxidant gas outlet manifold 74 includes corner members c1 to c4 disposed at corners of the oxidant gas outlet manifold 74 and straight members s1 to s4 disposed at straight portions of the oxidant gas outlet manifold 74. and s4. The corner members c1 to c4 are formed in substantially the same shape and size, and the linear members s1 to s4 are also formed in substantially the same shape and size. Next to the seal structure SL4, a seal structure SL5 for a cooling medium is formed. That is, the linear member s12 of the seal structure SL5 is formed next to the linear member s2 of the seal structure SL4, and the linear member s13 of the seal structure SL5 is formed next to the linear member s3 of the seal structure SL4.

  FIG. 4 is an explanatory view showing a cross section of four locations A, B, C and D of a seal structure SL4 surrounding the oxidant gas outlet manifold 74 shown in FIG. The seal structure SL4 is integrally formed with the central seal parts m1 to m4 and the central seal parts m1 to m4 on both sides of each central seal part m1 to m4, and the peripheral seal parts smaller in thickness than the central seal parts m1 to m4 and r1 to r4. In the present specification, “thickness” means the dimension in the stacking direction of the single cell 140. The central seal portions m1 to m4 function in sealing between the two single cells 140 in a state in which the plurality of single cells 140 are stacked. FIG. 4A is an explanatory view showing an A cross section of the linear member s4 of the seal structure SL4. FIG. 4B is an explanatory view showing a B cross section of the corner member c1 of the seal structure SL4. FIG. 4C is an explanatory view showing a C cross section of the linear member s2 of the seal structure SL4. FIG. 4D is an explanatory view showing a cross section D of the linear member s3 of the seal structure SL4. In FIGS. 4 (c) and 4 (d), a seal structure SL5 for the cooling medium is also depicted.

  The corner member c1 is disposed at a specific corner located at the corner of the anode side separator 50 among the four corners of the oxidant gas outlet manifold 74, and the straight member s4 is a straight part of the oxidant gas outlet manifold 74. Are arranged (Figure 3). Comparing FIG. 4A and FIG. 4B, the width Wc of the peripheral seal portion r1 of the corner member c1 is designed to be larger than the width Ws of the peripheral seal portion r4 of the linear member s4. On the other hand, the central seal portion m1 of the corner member c1 is designed with substantially the same shape and dimensions as the central seal portion m4 of the linear member s4. The straight member s2 in FIG. 4 (c) is designed with substantially the same shape and dimensions as the straight member s4. Further, the linear member s3 in FIG. 4 (d) is also designed with substantially the same shape and dimensions as the linear member s4. In the first embodiment, the shape characteristic of the corner member c1 is the same as that of the other corner members c2 to c4. Further, the geometrical features of the corner members and the straight members in the seal structure SL4 are the same as in the seal structures SL1 to SL3 surrounding the other reaction gas manifolds.

  In FIGS. 4A to 4D, the peripheral seal portions r1 to r4 are formed substantially in an L shape, and gaps G are provided on both sides of the central seal portions m1 to m4. Due to the presence of the gap G, when pressure is applied to the central seals m1 to m4 to seal between the single cells 140, the sealability of the central seals m1 to m4 can be enhanced. However, the gap G may be omitted, and a shape in which the seal member also exists in the gap G may be adopted.

  As described above, the width Wc of the peripheral seal portion of the corner members c1 to c4 of the seal structure SL4 is designed to be larger than the width Ws of the peripheral seal portion of the linear members s1 to s4, and the center of the corner members c1 to c4 is The seal is designed with substantially the same shape and dimensions as the central seal of the linear member. Thereby, when an internal pressure is applied to the seal structure SL4, the corner members c1 to c4 are difficult to expand outward, and the linear pressure decrease due to local elongation is suppressed, and the corner members c1 to c4 and the linear members s1 to s4 Since the leak of gas from the connection part of is prevented, sufficient sealing performance can be secured.

B. Second embodiment:
FIG. 5 is a schematic plan view showing the vicinity of the oxidant gas outlet manifold 74 in the second embodiment in an enlarged manner. The difference from the first embodiment shown in FIG. 3 is only in the shape of the three corner members c2a to c4a of the seal structure SL4a surrounding the oxidant gas outlet manifold 74, and the other configuration is the same as that of the first embodiment. Since it is the same, illustration and explanation are omitted.

  In the seal structure SL4a according to the second embodiment, the width of the peripheral seal portion is only the corner member c1 disposed at the specific corner portion located at the corner portion of the anode separator 50a among the corner portions of the oxidant gas outlet manifold 74 It is designed to be larger than the width of the peripheral seal portion of each of the linear members s1 to s4. That is, in each of the other corner members c2a to c4a, the width of the peripheral seal portion is formed to be substantially the same as the width of the peripheral seal portion of each of the linear members s1 to s4. When an internal pressure is applied to the seal structure SL4a, the corner member c1 is difficult to expand outward as described in the first embodiment, so that a decrease in linear pressure due to local elongation is suppressed, and sufficient sealing performance can be ensured. On the other hand, in the other corner members c2a to c4a, since the straight members s12 and s13 of the other seal structure SL5 exist next to the straight members s2 and s3 connecting the adjacent corner members to each other, the corner members c2a to c2 It provides a certain cushioning effect as c4a expands outward. Thereby, the linear pressure fall by local extension of corner members c2a-c4a is also controlled, and sufficient sealability is securable. As can be understood from this second embodiment, among the four corner members of the seal structures SL4 and SL4a surrounding the periphery of the manifold, at least the corner member c1 located at the corner portion of the separator, the width of the peripheral seal portion is other It is preferable that the width of the peripheral seal portion of the linear members s1 to s4 is designed to be larger than the width of the linear seal members s1 to s4. The geometrical characteristics of the corner member and the straight member in the seal structure SL4a are the same as in the seal structure surrounding the other reactive gas manifolds in the second embodiment.

C. Third embodiment:
FIG. 6 is a schematic plan view showing the vicinity of the oxidant gas outlet manifold 74 in the third embodiment in an enlarged manner. The only difference from the second embodiment shown in FIG. 5 is that the seal structure SL4b surrounding the oxidant gas outlet manifold 74 is integrated with the seal structure SL5 for the cooling medium, and the other configuration is the same as that of the second embodiment. Since the second embodiment is the same as the second embodiment, the illustration and the description will be omitted.

  FIG. 7 is an explanatory view showing a cross section of four locations A, B, C and D of a seal structure SL 4 b surrounding the oxidant gas outlet manifold 74 shown in FIG. FIG. 7A is an explanatory view showing a cross section A of the linear member s4 of the seal structure SL4b. FIG. 7B is an explanatory view showing a B cross section of the corner member c1 of the seal structure SL4b. FIG. 7C is an explanatory view showing a C cross section of the linear members s2b and s12b of the seal structures SL4b and SL5b. FIG. 7D is an explanatory view showing a D cross section of the linear members s3b and s13b of the seal structures SL4b and SL5b.

  The seal structure SL4b according to the third embodiment is the peripheral seal portion of the seal structure SL5b in which the portion of the peripheral seal portion of the seal structure SL4b extending from the linear member s2b to the linear member s3b in the clockwise direction in FIG. It is comprised so that it may connect integrally to the part of. For example, as shown in FIG. 7C, the peripheral seal portion r2b of the linear member s2b of the seal structure SL4b is connected to the peripheral seal portion r12b of the linear member s12b of the seal structure SL5. For example, as shown in FIG. 7D, the peripheral seal portion r3b of the linear member s3b of the seal structure SL4b is connected to the peripheral seal portion r13b of the linear member s13b of the seal structure SL5b.

  When an internal pressure is applied to the seal structure SL4b, the corner member c1 is difficult to expand outward as described in the first embodiment, so that a decrease in linear pressure due to local elongation is suppressed, and sufficient sealing performance can be ensured. On the other hand, since the other corner members c2b to c4b are connected to the adjacent seal structure SL5b, the corner members c2b to c4b are hard to expand outward and the linear pressure drop due to local elongation is suppressed, so sufficient. Good sealing performance. The geometrical characteristics of the corner members and the linear members in the seal structure SL4b are the same as in the seal structure surrounding the other reactive gas manifolds in the third embodiment.

・ Modification:
In the above embodiment, the reaction gas manifolds 62, 64, 72, 74 are provided at the corners of the anode separator 50. Instead, the manifolds 82, 84 for the cooling medium are at the corners of the anode separator 50. May be provided. In this case, the shape and dimensions described in the above embodiment may be applied to a corner member disposed at a specific corner of the anode separator 50 in the seal structure SL5 for the cooling medium. Is preferred.

  The present invention is not limited to the above-described embodiment and modification, and can be realized in various configurations without departing from the scope of the invention. For example, the technical features in the embodiments corresponding to the technical features in each of the modes described in the section of the summary of the invention can be used to solve some or all of the problems described above, or one of the effects described above. It is possible to replace or combine as appropriate to achieve part or all. Moreover, elements other than the element described in the independent claim in the constituent elements in each embodiment and modification mentioned above are additional elements, and can be omitted appropriately.

10: Fuel cell system 30: Membrane electrode assembly (MEA)
Reference Signs List 32 seal member 40 cathode side separator 42 oxidant gas flow channel groove 50, 50a anode side separator 52 fuel gas flow channel 54 cooling medium flow channel 56 dimples 62 fuel gas inlet communication manifold 64 Fuel gas outlet manifold 72 ... oxidant gas inlet communication manifold 74 ... oxidant gas outlet manifold 80 ... groove part 82 ... cooling medium inlet communication manifold 84 ... cooling medium outlet manifold 100 ... fuel cell stack 110 ... end plate 120 ... insulating plate 130 ... Current collector plate 140: Single cell 150: Hydrogen tank 151: Shut valve 152: Regulator 153: Piping 154: Discharge piping 160: Air pump 161: Piping 163: Discharge piping 170: Radiator 171: Water pump 172: Piping 173: Distribution 200: cooling medium flow path surface G: gap SL1 to SL5: seal structure SL4a, SL4b: seal structure SL5b: seal structure X: lamination direction Y: vertical direction Z: horizontal direction c1 to c4: corner member c2a to c4a: corner member c2b C4b: corner member m: central seal portion m1 to m4: central seal portion r: peripheral seal portion r1 to r4: peripheral seal portion r12 b: peripheral seal portion r13 b: peripheral seal portion r2 b: peripheral seal portion r3 b: peripheral seal portion s1 ~ S4 ... linear member s2b ... linear member s3b ... linear member s12, s12b ... linear member s13, s13b ... linear member

Claims (1)

A seal structure disposed between unit cells of a fuel cell and provided so as to surround the manifold of the separators of the unit cells,
The seal structure includes: a central seal that seals between the unit cells; and a peripheral seal that is integrally formed with the central seal on both sides of the central seal and that is thinner than the central seal. Equipped
Among the corner portions of the manifold, the width of the peripheral seal portion disposed at the specific corner portion located at the corner portion of the separator is larger than the width of the peripheral seal portion disposed at the linear portion of the manifold while being the width of the central sealing portion arranged in a particular corner portion is configured to the same the width of the central sealing portion arranged in the linear portion of the manifold,
Fuel cell seal structure.

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