JP2017123301A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent short-circuiting caused by electric conduction between separators when a foreign object enters a communication hole.SOLUTION: A fuel cell comprises: a power generation module having a membrane-electrode assembly, and first and second gas diffusion layers laminated on respective sides of the membrane-electrode assembly; a separator arranged along a surface on the first gas diffusion layer side of the power generation module; and a tabular seal member arranged, on a surface on the power generation module side of the separator, outside the power generation module. The separator has an opening at a position located outer side than a position opposite to the power generation module. The tabular seal member comprises: a manifold hole which communicates with the opening so as to configure a manifold for distributing reaction gas to the power generation module; and a communication hole which brings an internal space, where the first gas diffusion layer is arranged, into communication with the manifold hole. On a range, on the surface on the power generation module side of the separator, opposite to the communication hole, an insulating material is covered.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel cell.

  In general, a fuel cell includes a power generation module in which gas diffusion layers are arranged on both surfaces of a membrane electrode assembly, and two separators that sandwich the power generation module. The outside of the power generation module between the two separators is sealed by a resin seal member (see Patent Documents 1 and 2). Patent Document 1 discloses a configuration in which an opening communicating with an internal space in which a gas diffusion layer is disposed is formed in a resin frame member as a seal member.

JP 2014-63727 A JP 2013-251253 A

  In the prior art described above, the manifold penetrating between a pair of separators and the opening may be connected by a communication hole. In this configuration, the upper and lower surfaces of the communication hole are covered with the separator. In this structure, when foreign matter is mixed in the communication hole, there is a possibility that the separator is energized and short-circuited.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) One embodiment of the present invention is a fuel cell. The fuel cell includes a power generation module having a membrane electrode assembly and first and second gas diffusion layers stacked on both sides of the membrane electrode assembly, and the first gas diffusion layer of the power generation module. And a plate-shaped sealing member disposed outside the power generation module on the power generation module side surface of the separator. The separator includes an opening at a position outside the position facing the power generation module. The plate-like seal member communicates with the opening, and forms a manifold hole for distributing a reaction gas to the power generation module, an internal space in which the first gas diffusion layer is disposed, and the manifold hole A communication hole that communicates with each other. An insulating material is coated in a range facing the communication hole on the surface of the separator on the power generation module side.

  According to the fuel cell of this embodiment, the internal space where the first gas diffusion layer is disposed and the manifold hole are connected by the communication hole, and in a range facing the communication hole on the power generation module side surface of the separator, Since the insulating material is coated, it is possible to prevent the separator from being short-circuited with another pair of separators when foreign matter is mixed into the communication hole.

It is explanatory drawing which shows schematic structure of the fuel cell system in one Embodiment of this invention. It is the schematic plan view which looked at the anode side separator of the cell from the opposite side to MEGA. It is explanatory drawing which shows the AA cross section of the anode side separator shown in FIG. It is explanatory drawing which shows the method of forming a thin film layer. It is explanatory drawing which shows the cross section of the fuel cell in 2nd Embodiment. It is explanatory drawing which shows the cross section of the fuel cell in 3rd Embodiment.

A. First embodiment:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system 10 according to the first embodiment of the present invention. The fuel cell system 10 includes a fuel cell stack 100 as a fuel cell. The fuel cell stack 100 includes an end plate 110, an insulating plate 120, a current collecting plate 130, a plurality of fuel cell units (hereinafter also simply referred to as “cells”) 140, a current collecting plate 130, an insulating plate 120, The end plate 110 has a stack structure that is laminated in this order. Note that the stacking direction of the cells 140 is a direction X perpendicular to the vertical direction Y in this embodiment. The front-back direction in the figure perpendicular to the vertical direction Y and the stacking direction X is the front-rear direction Z. The front-rear direction Z is referred to as such because it corresponds to the front-rear direction of the vehicle when the fuel cell system 10 of the present embodiment is mounted on the vehicle.

  Hydrogen as fuel gas is supplied to the fuel cell stack 100 from a hydrogen tank 150 that stores 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 via 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 the air pump 160 and the pipe 161. The oxidant gas (cathode off gas) that has not been 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 reaction gas.

  Further, 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 in order to cool the fuel cell stack 100. 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 this example, water (also referred to as “cooling water”) is used as the cooling medium.

  Each cell 140 provided in the fuel cell stack 100 includes a membrane electrode gas diffusion layer assembly (MEGA) 30 as a power generation module, and a pair of separators 40 and 50 sandwiching the MEGA 30. ing. The MEGA 30 includes a membrane electrode assembly (MEA) 31 and a pair of gas diffusion layers 32 and 33 disposed on both surfaces of the MEA 31. One separator 50, that is, the anode-side separator 50, includes a plurality of streaky fuel gas passage grooves 52 on the MEGA 30 side surface, and a plurality of streaky cooling medium passage grooves 54 on the surface opposite to the MEGA 30. Is provided. The other separator 40, that is, the cathode-side separator 40 includes a plurality of oxidant gas flow channel grooves 42 in a streak shape on the surface on the MEGA 30 side.

  Each cell 140 further includes a plate-like seal member 80 disposed on the outer side (outer periphery) of the MEGA 30 between the anode side separator 50 and the cathode side separator 40 in the surface direction (YZ direction in the drawing). . The plate-like seal member 80 is a frame having a plate shape and a large hole on the inside and six manifold holes to be described later. The plate-shaped sealing member 80 seals between the anode side separator 50 and the cathode side separator 40 in a state where the MEGA 30 is disposed in the inner hole. As the plate-like seal member 80, for example, a resin such as PE, PP, PET, PEN can be used. The plate-like seal member 80 is adhered by adhesive layers 81 and 82 applied on both sides. As an adhesive constituting the adhesive layers 81 and 82, EPDM, epoxy, PIB or the like can be used. The adhesive layers 81 and 82 have insulating properties and water repellency.

  FIG. 2 is a schematic plan view of the anode separator 50 of the cell 140 as viewed from the side opposite to the MEGA 30. In FIG. 2, the front / back direction is the stacking direction X, the up / down direction is the vertical direction Y, and the left / right direction is the front / rear direction Z. The anode-side separator 50 and the cathode-side separator 40 are composed of members having gas barrier properties and electron conductivity. For example, a carbon-made member such as dense carbon that is made gas impermeable by compressing carbon particles, It is made of a press-molded metal member such as stainless steel or titanium steel. In the present embodiment, the separators 40 and 50 are metal press separators.

  A fuel gas inlet manifold 62, a coolant outlet manifold 78, and an oxidant gas inlet manifold 72 are arranged in order from the top along the vertical direction Y at one edge of the anode separator 50 in the front-rear direction Z. Yes. On the other hand, an oxidant gas outlet manifold 74, a cooling medium inlet manifold 76, and a fuel gas outlet manifold 64 are arranged along the vertical direction Y in order from the top at the other end edge. . The fuel gas inlet manifold 62 and the fuel gas outlet manifold 64, the oxidant gas inlet manifold 72 and the oxidant gas outlet manifold 74, and the cooling medium inlet manifold 76 and the cooling medium outlet manifold 78 are outer edge portions on both sides in the front-rear direction Z. Are arranged so as to face each other. Each manifold 62, 64, 72, 74, 76, 78 corresponds to a “manifold hole” in one embodiment of the present invention described in the “Summary of the Invention” column.

  The fuel gas supplied through the fuel gas pipe 153 (FIG. 1) is distributed to the fuel gas flow channel grooves 52 (FIG. 1) of the respective cells 140 by the fuel gas inlet manifold 62. Thereafter, the fuel gas that has not been used in the fuel gas passage groove 52 is collected by the fuel gas outlet manifold 64 and discharged to the outside of the fuel cell stack 100 through the discharge pipe 163 (FIG. 1). Further, the oxidant gas supplied via the oxidant gas pipe 161 (FIG. 1) is distributed to the oxidant gas flow channel 42 (FIG. 1) of each cell 140 by the oxidant gas inlet manifold 72. . Thereafter, the oxidant gas that has not been used in the oxidant gas passage groove 42 is collected by the oxidant gas outlet manifold 74 and discharged to the outside of the fuel cell stack 100 via the discharge pipe 154 (FIG. 1).

  The cooling medium inlet manifold 76, the cooling medium flow channel 54, and the cooling medium outlet manifold 78 communicate with each other in the front-rear direction Z on the plane of the anode side separator 50 as viewed from the side opposite to the MEGA 30. A flow path surface 190 is formed. The cooling medium supplied via the cooling medium pipe 172 (FIG. 1) is distributed to the cooling medium flow channel 54 of each cell 140 by the cooling medium inlet manifold 76. Thereafter, the cooling medium is collected by the cooling medium outlet manifold 78 and discharged to the outside of the fuel cell stack 100 via the pipe 173 (FIG. 1).

  Each manifold 62, 64, 72, 74, 76, 78 has a substantially rectangular opening. Each manifold 62, 64, 72, 74, 76, 78 has a shape extending in the stacking direction X of the fuel cell stack 100.

  As described above, the plate-shaped sealing member 80 is bonded to the outside in the surface direction (YZ direction in the drawing) of the anode-side separator 50 on the MEGA 30 side surface (that is, the back surface in FIG. 2). The plate-like seal member 80 includes a plurality of communication holes 90. Each communication hole 90 extends in the front-rear direction Z, and communicates the fuel gas inlet manifold 62 and the internal space SP (FIG. 1) in which the anode-side gas diffusion layer 33 of the MEGA 30 is disposed. That is, the communication hole 90 serves as a flow path that guides the fuel gas discharged from the fuel gas inlet manifold 62 to the anode gas diffusion layer 33 through the plate-shaped seal member 80. Although three communication holes 90 are shown in the drawing, the number of communication holes 90 is not limited to three, and may be another number (or even one).

  FIG. 3 is an explanatory view showing an AA section of the anode-side separator 50 shown in FIG. As illustrated, the plate-shaped seal member 80 described above is disposed between the anode-side separator 50 and the cathode-side separator 40. As described above with reference to FIG. 1, the plate-like seal member 80 is bonded to the separators 40 and 50 by the adhesive layers 81 and 82 arranged on both surfaces. Further, the plate-like seal member 80 includes a plurality of communication holes 90 as described above with reference to FIG. The front-rear direction Z, which is the direction in which the communication hole 90 extends, is the front-back direction in FIG.

  The opening of the communication hole 90 is substantially rectangular. Inner walls on both sides of the communication hole 90 in the stacking direction X are configured by the MEGA 30 side surfaces 40 a and 50 a of the separators 40 and 50. The thin film layers 81a and 82a are covered in a range facing the communication holes 90 on these surfaces 40a and 50a. As a result, the wall surfaces on the separator 40, 50 side in the communication hole 90 are covered with the thin film layers 81a, 82a. The cross-sectional shape shown in FIG. 3 is the configuration of the main part of the communication hole 90. In the communication hole 90, the portion close to the internal space SP where the anode-side gas diffusion layer 33 is arranged is the size of the aperture. Becomes smaller and is connected to the internal space SP.

  As described above, the separators 40 and 50 and the plate-like seal member 80 are bonded with an adhesive such as EPDM, epoxy, or PIB. These adhesives exhibit an adhesive function by applying heat and a load after being applied between the separators 40 and 50 and the plate-like seal member 80 (see FIG. 4). In the present embodiment, the amount of heat, load, and bonding time applied at the time of manufacture are increased as compared with the case where the separators 40 and 50 and the plate-shaped seal member 80 are simply bonded, and the adhesive is used for the plate-shaped seal. The thin film layers 81a and 82a are formed by melting the portion between the member 80 and the separators 40 and 50 (portions that become the adhesive layers 81 and 82) to the surroundings and the adhesive flowing out from both sides of the communication hole 90 connected. I did it. As a result, the thin film layers 81 a and 82 a are formed of the same material as that of the plate-shaped sealing member 80. In the present embodiment, the amount of heat, the load, and the bonding time are adjusted so that the thickness of the thin film layers 81a and 82a is several tens of μm. The thin film layers 81a and 82a thus formed have insulating properties and water repellency.

  Also between the anode side gas diffusion layer 33 and the fuel gas outlet manifold 64, between the oxidant gas inlet manifold 72 and the cathode side diffusion layer 32, and between the cathode side diffusion layer 32 and the oxidant gas outlet manifold 74. A communication hole (not shown) is provided. These communication holes have the same configuration as the communication hole 90 provided between the fuel gas inlet manifold 62 and the anode side gas diffusion layer 33 described above, and a thin film layer (not shown) is formed on the surface facing the separators 40 and 50. ) Is covered.

  As described in detail above, according to the fuel cell stack 100 of the present embodiment, the plate-shaped seal member 80 is provided between the internal space in which the anode-side gas diffusion layer 33 is disposed and the fuel gas inlet manifold 62. The thin film layers 81a and 82a are covered in a range facing the communication hole 90 on the surfaces 40a and 50a on the MEGA 30 side of the separators 40 and 50. For this reason, when a foreign material penetrates into the communication hole 90, it is possible to prevent the separators 40 and 50 from being energized and short-circuited.

  Further, according to the fuel cell stack 100, the thin film layers 81a and 82a have water repellency, so that the drainage of the fuel cell stack 100 can be improved. Furthermore, according to the fuel cell stack 100, the thin film layers 81a and 82a are made of the same material as the adhesive layers 81 and 82 to which the plate-like seal member 80 is bonded, and the plate-like seal member 80 and the separators 40 and 50 are joined. Since the thin film layers 81a and 82a are formed, the thin film layers 81a and 82a can be formed without increasing the number of parts. For this reason, the number of parts can be reduced and the productivity can be improved.

B. Second embodiment:
FIG. 5 is an explanatory view showing a cross section of the fuel battery cell 240 according to the second embodiment. This cross section shows a cross section at the same position as the AA cross section shown in FIG. Compared with the fuel cell 140 (FIG. 3) of the first embodiment, the fuel cell 240 of the second embodiment differs in the configuration of the thin film layers 281a and 282a and matches in the remaining points. In the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The thin film layers 281a and 282a correspond to the thin film layers 81a and 82a in the first embodiment. In the first embodiment, the thin film layers 81 a and 82 a are disposed only on the surface of the communication hole 90 facing the separators 40 and 50. On the other hand, in the second embodiment, the separator 40 in the communication hole 290. The thin film layers 281a and 282a are covered not only on the surface facing the surface 50, but also on the entire surfaces facing each other of the separators 40 and 50. In the present embodiment, thin sheets having insulating properties and water repellency are used as the thin film layers 281a and 282a. Thereby, the adhesive layers 81 and 82 of the plate-shaped sealing member 80 are joined to the separators 40 and 50 via the thin film layers 281a and 282a.

  The fuel cell 240 of the second embodiment configured as described above is energized between the separators 40 and 50 when a foreign object enters the communication hole 290, as in the fuel cell 140 of the first embodiment. Thus, it is possible to prevent a short circuit.

C. Third embodiment:
FIG. 6 is an explanatory view showing a cross section of the fuel battery cell 340 in the third embodiment. This cross section shows a cross section at the same position as the AA cross section shown in FIG. The fuel cell 340 of the third embodiment differs from the fuel cell 140 (FIG. 3) of the first embodiment in the configuration of the seal member 380 and matches the remaining points. In the third embodiment, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  The seal member 380 corresponds to the plate-like seal member 80, the adhesive layers 81 and 82, and the thin film layers 81a and 82a in the first embodiment, and is configured by one component. The seal member 380 is formed of a material having insulating properties and water repellency, and has a communication hole 390. Similar to the communication hole 90 of the first embodiment, the communication hole 390 communicates the internal space in which the anode-side gas diffusion layer 33 is disposed with the fuel gas outlet manifold 64. Further, the seal member 380 covers a range facing the communication hole 390 on the surface of the separators 40 and 50 on the MEGA 10 side.

  The fuel cell 340 of the third embodiment configured as described above is energized between the separators 40 and 50 when a foreign object enters the communication hole 390, like the fuel cell 140 of the first embodiment. Thus, it is possible to prevent a short circuit.

D. Variations:
In each of the embodiments and the modifications thereof, both the range facing the communication hole on the MEGA 30 side surface of the cathode side separator 40 and the range facing the communication hole on the MEGA 30 side surface of the anode side separator 50 are insulated. Coated with sex material. On the other hand, as a modification, only one of the two ranges may be covered with an insulating material.

  The present invention is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or one of the above-described effects. In order to achieve part or all, replacement or combination can be appropriately performed. Moreover, elements other than the elements described in the independent claims among the constituent elements in the respective embodiments described above are additional elements and can be omitted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 30 ... Membrane electrode gas diffusion layer assembly (MEGA)
31 ... Membrane electrode assembly (MEA)
32 ... Cathode side diffusion layer 33 ... Anode side gas diffusion layer 40 ... Cathode side separator 42 ... Oxidant gas passage groove 50 ... Anode side separator 52 ... Fuel gas passage groove 54 ... Cooling medium passage groove 62 ... Fuel gas inlet Manifold 64 ... Fuel gas outlet manifold 72 ... Oxidant gas inlet manifold 74 ... Oxidant gas outlet manifold 76 ... Cooling medium inlet manifold 78 ... Cooling medium outlet manifold 80 ... Plate seal member 81, 82 ... Adhesive layer 81a, 82a ... Thin film Layer 90 ... Communication hole 100 ... Fuel cell stack 110 ... End plate 120 ... Insulating plate 130 ... Current collecting plate 140 ... Fuel cell 150 ... Hydrogen tank 151 ... Shut valve 152 ... Regulator 153 ... Pipe 154 ... Discharge pipe 160 ... Air pump 161 ... Piping 163 ... Discharge piping DESCRIPTION OF SYMBOLS 70 ... Radiator 171 ... Water pump 172 ... Piping 173 ... Piping 190 ... Cooling medium channel surface 240 ... Fuel cell 281a, 22a ... Thin film layer 290 ... Communication hole 340 ... Fuel cell 380 ... Seal member 390 ... Communication hole SP ... Inside Space X ... stacking direction Y ... vertical direction Z ... front-back direction

Claims (1)

A fuel cell,
A power generation module having a membrane electrode assembly, and first and second gas diffusion layers laminated on both sides of the membrane electrode assembly;
A separator disposed along a surface on the first gas diffusion layer side of the power generation module;
A plate-like sealing member disposed outside the power generation module on the power generation module side surface of the separator;
With
The separator is
An opening is provided at a position outside the position facing the power generation module,
The plate-like sealing member is
A manifold hole that communicates with the opening and forms a manifold for distributing reaction gas to the power generation module;
A communication hole communicating the internal space in which the first gas diffusion layer is disposed and the manifold hole;
With
In a range facing the communication hole on the power generation module side surface of the separator, an insulating material is coated,
Fuel cell.

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