JP2005190760A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce pressing force actuated on the membrane electrode assembly caused by a seal material in a fuel cell. <P>SOLUTION: A second seal part 61 is arranged between a cooling liquid flow passage 50 and a cooling gas flow passage 55 on a second face 22b of each separator 22. The second seal part 61 is constructed so that it has a lower reaction force against the pressing force than a first seal part 60 and so that the same sealing capacity as that of the first seal part 60 will be exerted. Concretely, a sealing material having a lower reaction force than the first sealing material is used as the sealing material to constitute the second seal part 61. Therefore, the reaction force at the second seal part 61 is lower than that of the first seal part 60, thereby the pressing force via the cathode separator 22 on an electrolyte membrane 211 of the membrane electrode assembly can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell composed of single cells or a fuel cell in which a plurality of single cells are stacked.

  In a solid electrolyte membrane type fuel cell, a plurality of single cells are usually stacked in a stack. A single cell is generally sandwiched between an anode separator and a cathode separator having one surface on which a flow path forming portion for coolant is formed, and another surface for sandwiching a membrane electrode assembly, and the other surfaces of both separators. The membrane electrode assembly is provided. When stacking single cells, a sealing material is disposed at a predetermined position on one surface of an adjacent anode separator and a predetermined position on one surface of a cathode separator, and both separators are brought into contact with each other (see, for example, Patent Document 1). ).

  Further, when the coolant channel forming part is formed in a partial region of one surface of each separator, the coolant channel is formed from the region where the coolant channel forming part is formed. A sealing material is required to prevent the coolant from moving to the region where the formation portion is not formed. That is, it is necessary to prevent leakage of the cooling liquid from the cooling liquid flow path, to prevent a decrease in the amount of cooling liquid, and an unexpected leakage of the cooling liquid.

Japanese National Patent Publication No. 11-508726

  However, since the sealing material for preventing the movement of the cooling liquid is usually disposed near the center of the separator, the sealing material is pressed against the membrane electrode assembly held on the other surface due to the sealing material. There was a problem that pressure acted. The pressing force acting on the membrane electrode assembly may cause damage to the membrane electrode assembly and may hinder good diffusion of the reaction gas.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce a pressing force acting on a membrane electrode assembly due to a sealing material in a fuel cell.

In order to solve the above problems, a first aspect of the present invention provides a fuel cell. The fuel cell according to the first aspect of the present invention includes a membrane electrode assembly, a dense portion that does not allow liquid permeation, and a porous portion that permits liquid permeation, and is in contact with the membrane electrode assembly. A first surface having a reaction gas flow path forming portion that forms a reaction gas flow path when formed, a first coolant flow path forming portion formed in the dense portion, and a porous portion. A first separator having a second surface having a first cooling gas flow path forming portion, and a reactive gas flow path forming portion that forms a reactive gas flow path when contacting the membrane electrode assembly. A unit cell comprising: a first separator having a second separator comprising a first surface having a second surface having a second coolant flow passage forming portion and a second cooling gas passage forming portion;
When the unit cells are stacked and the second surface of the first separator and the second surface of the second separator are combined,
A first seal portion disposed between an outer edge portion of the second surface of the first separator and an outer edge portion of the second surface of the second separator; and formation of the first coolant flow path. A coolant flow path through which the coolant flows, and the first cooling gas flow path formation section and the second cooling gas flow path formation section. And a cooling gas flow path through which a cooling gas flows, and a second sealing portion that is disposed between and has a lower reaction force than the first sealing portion.

  According to the fuel cell of the first aspect of the present invention, the second seal portion disposed between the coolant flow path and the cooling gas flow path has a reaction force generated more than that of the first seal section. Since it is low, the pressing force applied to the membrane electrode assembly due to the reaction force of the seal portion can be reduced. As a result, it is possible to prevent damage to the membrane electrode assembly due to the pressing force, and it is possible to prevent hindering good diffusion of the reaction gas in the reaction gas flow path due to the pressing force. Moreover, the unexpected movement of the coolant from the coolant channel to the coolant gas channel can be prevented by the second seal portion.

  In the fuel cell according to the first aspect of the present invention, the first seal portion is a first seal material, and the second seal portion has a lower reaction force than the first seal material. The 2nd sealing material which has may be sufficient. In such a case, even if the same stress as the stress applied to the first seal portion is applied to the second seal portion, the second seal material has a low reaction force, and thus the second seal portion has a low reaction force. The reaction force generated at the portion can be made lower than the reaction force generated at the first seal portion.

  In the fuel cell according to the first aspect of the present invention, the second seal portion includes a first sandwiching portion formed on the second surface of the first separator, and a second separator. Formed by a second sandwiching portion formed on the second surface, and a sealing material sandwiched by the first sandwiching portion and the second sandwiching portion, and the sandwiching surface of the first sandwiching portion and the A seal distance increasing portion may be formed on the clamping surface of the second clamping portion. In such a case, since the seal distance (seal length) is increased by the seal distance increasing portion, sufficient sealing performance can be obtained even with a pressing force smaller than the pressing force applied to the first seal portion. . Therefore, the reaction force generated in the second seal portion can be made lower than the reaction force generated in the first seal portion.

  In the fuel cell according to the first aspect of the present invention, the sealing distance increasing portion may be a plurality of uneven portions. In such a case, since the surface area on the clamping surface can be increased and the pressure per unit area can be reduced, the reaction force generated in the second seal portion is made lower than the reaction force generated in the first seal portion. Can do.

  In the fuel cell according to the first aspect of the present invention, the depth of at least one recess among the plurality of recesses and projections may be deeper than the depth of other recesses. In such a case, the cooling liquid can be retained by a recess having a deeper depth than other recesses.

  In the fuel cell according to the first aspect of the present invention, the second seal portion includes a first holding portion formed on the second surface of the first separator, and a second portion of the second separator. Formed by a second clamping part formed on the second surface and a sealing material clamped by the first and second clamping parts, and the clamping surface of the first and second clamping parts and the sealing material May be modified with a predetermined functional group. In such a case, a bonding force is formed between the sealing material and the contact surfaces of the first and second holding portions by physical and chemical interaction between the functional groups, so that a smaller pressing force ( A sufficient sealing performance can be obtained by the pressure-bonding force) or without depending on the pressure-bonding force. Therefore, the reaction force generated at the second seal portion can be reduced.

  In the fuel cell according to the first aspect of the present invention, the second seal portion includes a first second seal portion forming portion formed on the second surface of the first separator, and the second seal portion. A second second seal portion forming portion formed on the second surface of the separator, and a substantially U-shaped opening, and the cooling in the first and second seal portion forming portions. You may form with the sealing material arrange | positioned facing the said substantially U-shaped opening part with respect to a liquid flow path. In such a case, since the sealing function for the coolant is realized by the internal pressure applied to the opening from the coolant channel, a sufficient sealing performance can be obtained without depending on the pressing force. Therefore, the reaction force generated at the second seal portion can be reduced.

  In the fuel cell according to the first aspect of the present invention, the sealing material may further include a substantially U-shaped opening directed to the cooling gas flow path. In such a case, since the sealing function is realized also by the internal pressure applied from the cooling gas flow path to the opening, further sufficient sealing performance can be obtained.

  In the fuel cell according to the first aspect of the present invention, the second separator includes a dense portion that does not allow liquid permeation and a porous portion that allows liquid permeation, and the second coolant flow The path forming part may be formed in the dense part, and the second cooling gas flow path forming part may be formed in the porous part. In such a case, liquids such as generated water can be discharged from the porous portion.

  In the fuel cell according to the first aspect of the present invention, the downstream end of the cooling gas channel may be in communication with the reaction gas channel formed by the first separator and the membrane electrode assembly. In such a case, since the cooling gas humidified by the porous portion can be used as the reaction gas, a humidifier for humidifying the reaction gas is unnecessary, or the humidifier can be downsized.

  In the fuel cell according to the first aspect of the present invention, the first separator is a cathode-side separator, the second separator is an anode-side separator, and the cooling gas is air as an oxidizing gas. May be. In such a case, the cooling gas can be used as the oxidizing gas as the reaction gas.

  In the fuel cell according to the first aspect of the present invention, the coolant may be an aqueous ethylene glycol solution. In such a case, freezing of the cooling liquid can be prevented. Further, in the fuel cell according to the first aspect of the present invention, even when an antifreeze liquid is used as the coolant, the membrane electrode assembly, particularly the electrolyte membrane, can be prevented from being damaged by the antifreeze liquid. Accordingly, an antifreeze liquid can be used as the cooling liquid.

  According to a second aspect of the present invention, there is provided a pair of separators, at least one of which includes a dense part that does not allow liquid permeation and a porous part that allows liquid permeation, and a membrane electrode sandwiched between the pair of separators. Provided is a fuel cell in which a plurality of unit cells including a joined body are stacked. The fuel cell according to the second aspect of the present invention is formed in a portion corresponding to the dense portion in the adjacent portion of each unit cell, and corresponds to the coolant flow path through which the coolant flows and the porous portion. A cooling gas flow path formed in a portion to be formed, a first seal portion disposed at an outer edge, and the cooling liquid flow path and the cooling gas flow path are disposed between the cooling liquid flow path and the cooling gas flow path. And a second seal portion that separates the cooling gas flow path and has a lower reaction force to stress than the first seal portion.

  According to the fuel cell according to the second aspect of the present invention, the same effect as the fuel cell according to the first aspect of the present invention can be obtained, and the fuel cell according to the second aspect of the present invention provides In the same manner as the fuel cell according to the first aspect of the present invention, it can be realized in various aspects.

  Hereinafter, a fuel cell according to the present invention will be described based on several embodiments with reference to the drawings.

First embodiment:
A schematic configuration of the fuel cell according to the first embodiment will be described with reference to FIGS. FIG. 1 is an explanatory view schematically showing an example of the external configuration of the fuel cell according to the first embodiment. FIG. 2 is an explanatory view schematically showing the configuration of the first surface (contact surface with the membrane electrode assembly) of the cathode separator which is a component of the fuel cell of the first embodiment. FIG. 3 is an explanatory diagram schematically showing the configuration of the second surface (cooling flow channel side surface) of the cathode separator, which is a component of the fuel cell of the first embodiment. FIG. 4 is an explanatory diagram schematically showing the configuration of the first surface (contact surface with the membrane electrode assembly) of the anode separator which is a component of the fuel cell of the first embodiment. FIG. 5 is an explanatory view schematically showing a longitudinal section obtained by cutting a part of the fuel cell 10 according to the first embodiment in the longitudinal direction (for example, along line 5-5 in FIG. 2).

  The fuel cell 10 according to the first embodiment includes a plurality of single cells 20, an end plate 30, and a tension plate 31. The plurality of single cells 20 are sandwiched between two end plates 30, and a tension plate 31 is coupled to each end plate 30 by bolts 32, thereby forming a stacked fuel cell 10.

  The single cell 20 includes a membrane electrode assembly 21, a cathode separator 22, and an anode separator 23. A plurality of single cells 20 are stacked such that the cathode separator 22 and the anode separator 23 are in contact with each other.

  As shown in detail in FIG. 5, the membrane electrode assembly 21 includes an electrolyte membrane 211 made of an ion exchange membrane and an electrode made of a catalyst layer disposed on one surface of the electrolyte membrane 211 (for example, an anode electrode, not shown). 1), an electrode (for example, a cathode electrode, not shown) made of a catalyst layer disposed on the other surface of the electrolyte membrane 211, and a diffusion layer 212 disposed on the separator facing surface of each catalyst layer. The membrane / electrode assembly 21 is composed of an electrolyte membrane 211 and a catalyst layer (electrode), and a diffusion layer may be provided as a separate component. In any case, the electrolyte membrane 211, the catalyst layer, and the diffusion layer are sandwiched between the separators 22 and 23.

  The cathode separator 22 is made of a conductive material such as carbon, metal, or conductive resin. Although most of the cathode separator 22 is formed of a dense portion, the cathode separator 22 is formed of a porous portion 40 in the lower central region in FIGS. The porous portion 40 can be formed of the same material as the dense portion by using a porous metal such as carbon, sintered metal, or metal mesh formed in a porous shape, for example. The porous portion 40 may be molded integrally with the dense portion, or may be joined or bonded to the dense portion after being separately molded.

  The cathode separator 22 includes a first surface 22a that is a contact surface with the membrane electrode assembly 21 (cathode electrode) and a second surface 22b in which a cooling channel is formed. The cathode separator 22 includes an oxidizing gas supply manifold forming portion 221a, an oxidizing gas exhaust manifold forming portion 221b, a fuel gas supply manifold forming portion 222a, and a fuel gas exhaust manifold forming portion 222b. These forming portions 221a, 221b, 222a, and 222b form an oxidizing gas supply manifold, an oxidizing gas exhaust manifold, a fuel gas supply manifold, and a fuel gas exhaust manifold, respectively, when stacked. Note that air is generally used as the oxidizing gas, and hydrogen is generally used as the fuel gas. Further, both the oxidizing gas and the fuel gas are also called reaction gases.

  The cathode separator 22 further includes a coolant supply manifold forming portion 223a, a coolant discharge manifold forming portion 223b, a coolant gas supply manifold forming portion 224a, and a coolant gas exhaust manifold forming portion 224b. Each of these forming portions 223a, 223b, 224a, 224b forms a cooling liquid supply manifold, a cooling liquid discharge manifold, a cooling gas supply manifold, and a cooling gas exhaust manifold, respectively, when stacked. As is clear from FIGS. 2 and 3, the cooling gas exhaust manifold forming portion 224b and the oxidizing gas supply manifold forming portion 221a are realized by the same opening, and also function as a cooling gas exhaust portion and an oxidizing gas supply portion, respectively. To do. These coolant and cooling gas are used to cool the fuel cell 10. As the cooling liquid, for example, an antifreezing liquid containing ethylene glycol as a component is used in order to prevent freezing in a sub-freezing environment. As the cooling gas, for example, air that can be used as an oxidizing gas is used.

  The first surface 22a of the cathode separator 22 will be described in detail with reference to FIG. An oxidizing gas (reactive gas) flow path forming portion that forms an oxidizing gas flow path (reactive gas flow path) by being in contact with and covered with the membrane electrode assembly 21 at substantially the center of the first surface 22a of the cathode separator 22. 225 is formed. The oxidizing gas flow path forming part 225 is partitioned into a plurality of linear flow path forming parts by the ribs 70. A first seal portion 60 (seal material) is disposed around the outer peripheral edge portion of the first surface 22a of the cathode separator 22 and around each manifold forming portion in order to prevent leakage and mixing of each fluid. ing.

  In addition, as an oxidizing gas flow path, you may take the shape of a serpentine flow path other than a linear flow path. Further, the oxidizing gas flow path forming unit 225 may include a plurality of protrusions instead of the ribs 70 and partition the oxidizing gas flow path by the plurality of protrusions.

  The oxidant gas introduced from the oxidant gas supply part 221a into the oxidant gas flow path forming part 225 flows, for example, as shown in FIG. 2, and passes from the oxidant gas exhaust manifold formation part 221b to the outside of the separator (oxidant gas exhaust manifold). Discharged.

  Generally, on the cathode side of the fuel cell 10, water (product water) is generated due to the electromotive reaction, so that the region DA close to the oxidizing gas supply unit 221 a in the region of the oxidizing gas flow path forming unit 225 is While relatively dry, the area WA close to the oxidizing gas exhaust manifold forming portion 221b tends to be wet. On the other hand, in the first embodiment, since the lower part of the cathode separator 22 is composed of the porous part 40, the generated water is absorbed by the porous part 40, and a cooling gas passage 55 described later. So that so-called flooding is prevented.

  The second surface 22b of the cathode separator 22 will be described in detail with reference to FIG. The second surface 22 b of the cathode separator 22 includes a cooling liquid flow path forming part 226 that is a dense part and a cooling gas flow path forming part 227 including the porous part 40. The coolant flow path forming portion 226 and the cooling gas flow path forming portion 227 are combined with the second surface 22b of the cathode separator 22 and the second surface 23b of the anode separator 23 having the same flow path forming portions. As a result, the coolant channel 50 and the coolant gas channel 55 are formed.

  The coolant flow path forming part 226 communicates with the coolant supply manifold forming part 223a and the coolant discharge manifold forming part 223b, and cools the fuel cell 10 by liquid cooling. The cooling gas flow path forming unit 227 communicates with the cooling gas supply unit 224a and the cooling gas exhaust manifold forming unit 224b, and cools the fuel cell 10 by air cooling.

  The cooling gas passing through the cooling gas flow path forming part 227 is humidified when passing through the porous part 40. Since the porous portion 40 contains generated water as described above, when the dry cooling gas passes (contacts), moisture contained by capillary phenomenon and vaporization phenomenon is taken away by the cooling gas, that is, The cooling gas is humidified. The humidified cooling gas is guided from the cooling gas exhaust manifold forming part 224b, that is, the oxidizing gas supply part 221a, to the oxidizing gas flow path forming part 225. Therefore, the humidified cooling gas can be used as the oxidizing gas.

  On the second surfaces 22b and 23b of the separators 22 and 23, there is a second gap between the cooling liquid flow path 50 (cooling liquid flow path forming part 226) and the cooling gas flow path 55 (cooling gas flow path forming part 227). The sealing portion 61 (intermediate sealing material) is disposed. The second seal portion 61 is provided to prevent movement (leakage) of the coolant into the cooling gas flow path.

  In general, the peripheral area of the intermediate seal material on the second surface of the cathode separator 22 is pushed higher than the other areas on the second surface of the cathode separator 22 by the intermediate seal material that provides a sealing function by the pressure seal. This is the area where pressure is generated. Therefore, a high pressing force acts on the membrane electrode assembly 21 via the rib 70 on the first surface of the cathode separator 22.

  However, the second seal portion 61 in the first embodiment is such that the reaction force against the pressing force is lower than the reaction force of the first seal portion 60, and even with a low reaction force, the first seal portion 60. It is configured to exhibit the same sealing ability as That is, as will be described later, as the sealing material constituting the second sealing portion 61, a sealing material having a lower reaction force than the sealing material in the first sealing portion is used. Therefore, the reaction force in the second seal portion 61 is lower than the reaction force in the first seal portion 60, and the pressing force applied to the electrolyte membrane 211 of the membrane electrode assembly 21 through the cathode separator 22 is reduced. Can do.

  The anode separator 23 is formed of a conductive material such as carbon, metal, or conductive resin, for example, in the same manner as the cathode separator 22. The anode separator 23 in the first embodiment is formed of a dense portion and a porous portion 40 in the same manner as the cathode separator 22. The anode separator 23 includes a first surface 23a that is a contact surface with the membrane electrode assembly 21 (anode electrode), and a second surface 23b in which a cooling channel is formed.

  The anode separator 23 includes an oxidizing gas supply manifold forming portion 231a, an oxidizing gas exhaust manifold forming portion 231b, a fuel gas supply manifold forming portion 232a, and a fuel gas exhaust manifold forming portion 232b. These forming portions 231a, 231b, 232a, and 232b form an oxidizing gas supply manifold, an oxidizing gas exhaust manifold, a fuel gas supply manifold, and a fuel gas exhaust manifold, respectively, when stacked.

  The anode separator 23 further includes a coolant supply manifold forming portion 233a, a coolant discharge manifold forming portion 233b, a coolant gas supply manifold forming portion 234a, and a coolant gas exhaust manifold forming portion 234b. Each of these forming portions 233a, 233b, 234a, 234b forms a cooling liquid supply manifold, a cooling liquid discharge manifold, a cooling gas supply manifold, and a cooling gas exhaust manifold when stacked.

  The first surface 23a of the anode separator 23 will be described in detail with reference to FIG. A fuel gas (reactive gas) flow path forming portion that forms a fuel gas flow path (reactive gas flow path) by being in contact with and covered with the membrane electrode assembly 21 at substantially the center of the first surface 23a of the anode separator 23. 235 is formed. The fuel gas flow path forming portion 235 is partitioned into a plurality of linear flow path forming portions by the ribs 70.

  Similarly to the second surface 22 b of the cathode separator 22, the cooling liquid flow path 50 (cooling liquid flow path forming portion 226) and the cooling gas flow path 55 (cooling gas flow 55) are also formed on the second surface 23 b of the anode separator 23. A second seal portion 61 is disposed (formed) between the passage forming portion 227). In addition, a first seal portion 60 is disposed (formed) around the outer edge portion of the second surface 23b of the anode separator 23 and around each manifold forming portion.

  In addition to the linear flow path, the fuel gas flow path may take the shape of a serpentine flow path. Further, the fuel gas flow path forming unit 225 may include a plurality of protrusions instead of the ribs 70 and partition the fuel gas flow path by the plurality of protrusions.

  The fuel gas introduced from the fuel gas supply manifold forming portion 232a into the fuel gas flow path forming portion 235 flows, for example, as indicated by the arrow in FIG. 4, and is discharged from the fuel gas exhaust manifold forming portion 232b to the outside of the separator. Is done.

  Since the configuration of the second surface 23b of the anode separator 23 is the same as that of the second surface 22b of the cathode separator 22, the same components are denoted by the same reference numerals and the description thereof is omitted.

  A specific configuration of the second seal portion 61 in the first embodiment will be described with reference to FIG. FIG. 6 is an enlarged view schematically showing the second seal portion 61 in the first embodiment. The second seal portion 61 formed (arranged) on the cathode separator 22 and the anode separator 23 in the first embodiment has a lower reaction force than the seal material used for the first seal portion 60 against stress. In the low reaction force seal material 611 shown, the seal material pool portion 612 that stores the excess low reaction force seal material 611, the bead portion 613 that realizes the seal function by sandwiching the low reaction force seal material 611, and the second seal portion 61 A partition portion 614 that partitions the bead portion 613 from the coolant flow path and the coolant gas flow path is provided.

  As the low reaction force sealing material 611, for example, a rubber material (elastic material) with reduced hardness, a gelling agent, and an adhesive are suitable. As a gelling agent, for example, Tetrax manufactured by Nippon Oil Corporation, which is a semi-solid polymer polyisobutylene, can be used. Moreover, the adhesive generally does not cause a reaction force due to the adhesive.

  Here, generally, the sealing characteristics are determined by the length of the sealing portion (bead portion 613), and the longer the sealing portion length, the better the sealing characteristics. On the other hand, in order to reduce the pressing force applied to the membrane electrode assembly 21 by the second seal portion 61, the pressing force on the membrane electrode assembly 21 can be reduced as the gap between the bead portions 613 is thicker. Therefore, the length of the bead part 613 is taken as long as possible, and the height of the bead part 613 is formed lower than the height of the partition part 614.

  Furthermore, the height of the bead portion 613 may be lower than the height of these ribs when the ribs that define the flow paths are formed in the cooling liquid flow path 50 and the cooling gas flow path 55. preferable. By forming the bead portion 613 to be lower than the rib height, a gap is secured in the bead portion 613, and coupled with the low reaction force low reaction force seal material 611, the membrane electrode assembly is formed by the second seal portion 61. The stress given to 21 can be reduced.

  Another configuration example of the second seal portion using the low reaction force seal material 611 will be described with reference to FIGS. 7 and 8. FIG. 7 is an explanatory view schematically showing a first modification of the second seal portion in the first embodiment. FIG. 8 is an explanatory view schematically showing a second modification of the second seal portion in the first embodiment.

  The second seal portion 61a formed (arranged) on the cathode separator 22 and the anode separator 23 according to the first modification shown in FIG. 7 is provided with a low reaction force seal material 611a instead of the bead portion 613. The receiving portion 615 is provided. The low reaction force sealing material 611a has a convex shape and is disposed (filled) over the entire area of the accommodating portion 615, and achieves good sealing characteristics depending on the distance.

  The second seal portion 61b formed (arranged) in the cathode separator 22 and the anode separator 23 according to the second modification shown in FIG. 8 is the same as the second seal portion 61a according to the first modification. Although having the configuration, a plurality of low reaction force sealing materials 611b having a convex shape are provided to achieve good sealing characteristics. Note that the low reaction force sealing material 611b may be configured such that one sealing material includes a plurality of convex portions (mountain portions).

  As described above, in the fuel cell 10 according to the first embodiment, the reaction force against the pressing force is greater than the reaction force of the first seal portion 60 disposed (formed) at the outer edge portion of each separator 22, 23. A low second seal portion 61 (low reaction force seal material 611) is provided. Accordingly, the reaction force at the second seal portion 61 can be made lower than the reaction force at the first seal portion 60, and the pressing force applied to the electrolyte membrane 211 of the membrane electrode assembly 21 via the cathode separator 22. Can be reduced. As a result, it is possible to prevent damage to the electrolyte membrane of the membrane electrode assembly 21 due to the pressing force caused by the second seal portion 61. In addition, since the second seal portion 61 can prevent or suppress the collapse of the diffusion layer 212 due to the pressing force caused by the second seal portion 61, it is possible to maintain good diffusibility of the reaction gas. Therefore, the battery life can be extended.

  Further, since the second seal portion 61 is configured to exhibit the same sealing ability as the first seal 60 even with a low reaction force, the cooling gas flow path 50 (cooling gas flow path 226) to the cooling gas flow path. The movement and leakage of the coolant to 55 (cooling gas flow path forming part 227) can be prevented. Therefore, even when an antifreeze such as ethylene glycol is used as the coolant, the coolant does not reach the membrane electrode assembly 21 from the porous portion 40, and the dissolution of the electrolyte membrane 211 by the alcohol component of the antifreeze can be prevented. it can. In addition, even when pure water is used as the cooling liquid, it is possible to prevent the situation where pure water is supplied to the membrane electrode assembly 21 without any adjustment.

  In the fuel cell according to the first aspect of the present invention, the downstream ends of the cooling gas flow paths in the cathode separator 22 and the anode separator 23 are communicated with the oxidizing gas flow path forming part 225 of the cathode separator 22. Therefore, since the cooling gas humidified by the porous portion 40 can be used as the oxidizing gas, a humidifier for humidifying the oxidizing gas is unnecessary, or the humidifier can be downsized.

Second embodiment:
The second seal portion in the fuel cell according to the second embodiment will be described with reference to FIGS. FIG. 9 is an explanatory view schematically showing a first mode of the second seal portion in the second embodiment. FIG. 10 is an explanatory view schematically showing a second mode of the second seal portion in the second embodiment. FIG. 11 is an explanatory view schematically showing a third mode of the second seal portion in the second embodiment.

  Since the fuel cell according to the second embodiment has the same configuration as that of the fuel cell 10 according to the first embodiment except for the configuration of the second seal portion, description of each component will be given in the first embodiment. The description is omitted by using the same reference numerals as those used in the examples.

  In the second embodiment, the second seal portion 62 formed (arranged) on the cathode separator 22 and the anode separator 23 achieves good sealing characteristics without depending on the pressing force by taking a long seal length. At the same time, the pressing force per unit area is reduced by increasing the surface area, thereby reducing the reaction force. This will be specifically described using the first mode shown in FIG. The first aspect of the second seal portion 62 includes a bead portion 621 having an irregular shape formed in a mountain shape, and a sealing material 622 disposed between the bead portions 621. The bead portion 621 has a chevron-shaped uneven portion, thereby increasing the surface area and consequently increasing the seal length as compared to a smooth surface-like body.

  When the surface area of the bead portion 621 is increased, the pressure per unit area with respect to the same pressing force is reduced, and the pressing force applied to the sealing material 622 is reduced, so that the reaction force of the sealing material 622 is also reduced. In addition, by increasing the seal length of the bead portion 621, it is possible to realize good sealing characteristics and improve gas barrier properties. In addition, as the sealing material 622, the same sealing material as the sealing material used for the first seal portion 60 may be used, and further, a sealing material having a low reaction force characteristic is preferably used.

  The second seal portion 62a formed (arranged) in the cathode separator 22 and the anode separator 23 in the second mode shown in FIG. 10 includes a bead portion 623 whose surface is unevenly roughened. Such a bead portion 623 also increases the seal length and the bead portion surface area.

  The second seal portion 62b formed (arranged) in the cathode separator 22 and the anode separator 23 in the third mode shown in FIG. 11 includes a bead portion 624 having a plurality of hemispherical seal material pool portions 625. Yes. Such a bead portion 624 also increases the seal length and the bead portion surface area. Further, since the permeated gas contained in the sealing material stays in the sealing material collected in the sealing material pool portion 625, the gas barrier property can be improved.

  As described above, the second seal portion 62 (62a, 62b, 62c) in the second embodiment has a shape that increases the surface area of the bead portion (seal portion) on the surface (contact surface). Therefore, the surface pressure in the second seal portion 62 can be lowered, and as a result, the reaction force of the second seal portion 62 can be reduced. Therefore, the pressing force applied to the electrolyte membrane 211 of the membrane electrode assembly 21 through the cathode separator 22 is reduced, and the electrolyte membrane of the membrane electrode assembly 21 due to the pressing force caused by the second seal portion 62 is prevented. be able to. In addition, since the second seal portion 62 can prevent or suppress the collapse of the diffusion layer 212 due to the pressing force caused by the second seal portion 62, it is possible to maintain good diffusibility of the reaction gas. Therefore, the battery life can be extended.

  Furthermore, since the second seal part 62 has a shape that increases the seal length of the bead part (seal part), it is possible to realize a good sealing characteristic against antifreeze and improve the gas barrier property. Therefore, the movement and leakage of the cooling liquid from the cooling liquid flow path 50 (cooling gas flow path 226) to the cooling gas flow path 55 (cooling gas flow path forming portion 227) can be prevented. As a result, even when an antifreeze such as ethylene glycol is used as the cooling liquid, the cooling liquid does not reach the membrane electrode assembly 21 from the porous portion 40, and the dissolution of the electrolyte membrane 211 by the alcohol component of the antifreezing liquid is prevented. Can do.

Third embodiment:
A second seal portion in the fuel cell according to the third embodiment will be described with reference to FIGS. FIG. 12 is an explanatory view schematically showing a first aspect of the second seal portion in the third embodiment. FIG. 13 is an explanatory view schematically showing a second mode of the second seal portion in the third embodiment. FIG. 14 is an explanatory view schematically showing a third mode of the second seal portion in the third embodiment. FIG. 15 is an explanatory view schematically showing a fourth aspect of the second seal portion in the third embodiment.

  The fuel cell according to the third embodiment has the same configuration as that of the fuel cell 10 according to the first embodiment except for the configuration of the second seal portion. The description is omitted by using the same reference numerals as those used in the examples.

  In the third embodiment, the second seal portion 63 formed (arranged) on the cathode separator 22 and the anode separator 23 is excellent without depending on the pressing force by modifying the seal surface with a predetermined functional group. By realizing the sealing characteristics and not depending on the pressing force, the reaction force caused by the second seal portion 63 is reduced. This will be specifically described using the first mode shown in FIG. The 1st aspect of the 2nd seal | sticker part 63 is equipped with the bead part 631 by which the hydrophilic functional group was modified, and the sealing material 632 containing the functional group with high affinity with the modified functional group.

  In the example of FIG. 12, the bead portion 631 is modified with a molecular chain having a hydroxyl group at the end (—R—OH), and the sealing material 632 also has a molecular chain having a hydroxyl group at the end (—R—OH). ) Is included. Therefore, when an acid solution such as an ethylene glycol aqueous solution comes into contact with the bead part 631 and the sealing material 632 after the sealing material 632 is inserted, a condensation reaction occurs between the hydroxyl groups of both molecular chains, water molecules are removed, and the functionality of the bead part 631 is detected. Since the base and the functional group of the sealing material 632 are combined to form a stronger sealing surface, the penetration of ethylene glycol is prevented without impairing the contact property of the sealing portion even under a low load. In addition to the hydroxyl group, for example, a carboxylic acid group (—COOH) may be used as a functional group. In such a case, an acid solution such as an ethylene glycol aqueous solution functions as an acid catalyst, and a crosslink is formed by dehydration polymerization of a carboxylic acid and an alcohol to form a strong sealing surface.

  That is, a bonding force is generated between the bead portion 631 and the sealing material 632 by physical and chemical interaction between the functional groups, and good sealing characteristics for preventing the penetration of the cooling liquid are realized. As described above, since the sealing function is realized by utilizing the physical and chemical interaction between the functional groups, the sealing characteristic in the second sealing portion 63 does not depend on the pressing force. In addition to this, an aldehyde group, a ketone group, an acetyl group, and an amino group can be used as the hydrophilic functional group. That is, any functional group that causes a cross-linking reaction may be used using a chemical species contained in the coolant as a cross-linking agent.

In the second mode shown in FIG. 13, the second seal portion 63a formed (arranged) on the cathode separator 22 and the anode separator 23 includes a bead portion 633 that has been subjected to a hydrophobic treatment, and a seal material that includes a hydrophobic group. 634. In such a case, when the ethylene glycol aqueous solution touches the bead portion 633 and the sealing material 634, a hydrophobic bond is formed. Therefore, such chemical bonding prevents further penetration of the aqueous ethylene glycol solution. As the hydrophobic group, an alkyl group (—C _n H _{2n + 1} ), a phenyl group (—C ₆ H ₅ ), or an inorganic compound such as fluorine or silica can be used. As the hydrophobic treatment, silane coupling with dimethylcyclosilane (C ₂ H ₆ Cl ₂ Si) or the like can be used.

  The second mode shown in FIG. 13 can also be realized as the third mode shown in FIG. In the third embodiment, the second seal portion 63b formed (arranged) on the cathode separator 22 and the anode separator 23 includes a bead portion 635 having a hydrophilic treatment applied to the end portion on the coolant flow path side and a hydrophobic group. A sealing material 636 is included. In such a case, the sealing material 636 is sealed between the bead portions 635 by the repulsive force between the hydrophilic group and the hydrophobic group. Therefore, good sealing characteristics can be obtained without depending on the pressing force.

  In the fourth embodiment shown in FIG. 15, the second seal portion 63c formed (arranged) on the cathode separator 22 and the anode separator 23 has a high electronegativity of hydrogen atoms such as amino groups, hydroxyl groups, and carboxyl groups. A bead portion 637 that has been subjected to a hydrophilic treatment with a functional group bonded to an atom, and a sealing material 638 having a surface that has been subjected to a hydrophilic treatment with a similar functional group containing a hydrogen atom are provided. In such a case, a hydrogen bond is formed between the bead portion 637 and the sealing material 638. Therefore, such chemical bonding prevents further penetration of the aqueous ethylene glycol solution.

  As described above, the second seal portion 63 (63a, 63b, 63c) in the third embodiment modifies the seal surface of the bead portion with a predetermined functional group, and the seal material is used to modify the bead portion. A functional group having high affinity with the functional group used is included. Therefore, a non-covalent bond such as a covalent bond or a hydrogen bond or a hydrophobic bond is formed in the second seal portion 63 by a chemical / physical interaction, and good seal characteristics can be realized by the formed bond. it can. Therefore, the second seal part 63 can prevent the coolant from moving and leaking from the coolant channel 50 (cooling gas channel 226) to the coolant gas channel 55 (cooling gas channel forming part 227). it can. As a result, even when an antifreeze such as ethylene glycol is used as the cooling liquid, the cooling liquid does not reach the membrane electrode assembly 21 from the porous portion 40, and the dissolution of the electrolyte membrane 211 by the alcohol component of the antifreezing liquid is prevented. Can do.

  In addition, since the seal characteristic in the second seal portion 63 is obtained by the bonding force formed by the chemical / physical interaction, it does not depend on the pressing force (crimping force) and is attributed to the second seal portion 63. The reaction force to be reduced can be reduced. Therefore, the pressing force applied to the electrolyte membrane 211 of the membrane electrode assembly 21 through the cathode separator 22 is reduced, and the electrolyte membrane of the membrane electrode assembly 21 is prevented from being damaged by the pressing force caused by the second seal portion 63. be able to. In addition, since the second seal portion 63 can prevent or suppress the collapse of the diffusion layer 212 due to the pressing force due to the second seal portion 63, it is possible to maintain good diffusibility of the reaction gas. Therefore, the battery life can be extended.

Fourth embodiment:
A second seal portion in the fuel cell according to the fourth embodiment will be described with reference to FIG. FIG. 16 is an explanatory view schematically showing a second seal portion in the fourth embodiment. The fuel cell according to the fourth embodiment has the same configuration as that of the fuel cell 10 according to the first embodiment except for the configuration of the second seal portion. By using the same reference numerals as those used in the embodiment, the description is omitted.

  In the fourth embodiment, the second seal portion 64 formed (arranged) on the cathode separator 22 and the anode separator 23 has the working pressure (internal pressure) of the coolant from the coolant channel and the coolant gas channel. The sealing function is realized by the working pressure (internal pressure) of the cooling gas.

  The second seal portion 64 has a seal member 642 in which each opening 641 is directed to the coolant channel and the coolant gas channel, a storage portion 643 for storing the seal member 642, and the position of the central portion of the seal member 642. In order to define, a defining part 644 formed substantially at the center of the storage part 643, a cooling liquid introducing part 645 for introducing the cooling liquid from the cooling liquid flow path, and a cooling gas introducing part 646 for introducing the cooling gas from the cooling gas flow path are provided. I have.

  In the second seal portion 64, the opening 641 of the seal material 642 is expanded by the coolant introduced via the coolant introduction portion 645 and abuts against the inner wall surface 643 a of the storage portion 643, and the coolant gas introduction portion 646 is The opening 641 of the sealing material 642 is pushed and expanded by the cooling gas introduced through the cooling gas and comes into contact with the inner wall surface 643b of the storage portion 643. Therefore, in the second seal portion 64, the seal 642 (643a, 643b) is brought into contact with the respective opening portions 641 of the seal material 642 expanded by the internal pressure from the coolant flow path and the coolant gas flow path. Function is realized. With such a shape, almost no reaction force is generated in the second seal portion 64.

  Note that the sealing material 642 may have the shape shown in FIG. FIG. 17 is an explanatory view schematically showing another aspect of the second seal portion in the fourth embodiment. That is, if good sealing characteristics can be exhibited with respect to the coolant channel, damage to the membrane electrode assembly 21 (electrolyte membrane 211) due to leakage of the coolant can be prevented.

  As described above, the second seal portion 64 in the fourth embodiment uses the internal pressure from the coolant flow path and the coolant gas flow path to expand and widen each opening 641 of the seal material 642, A sealing function is realized by bringing the opening portion 641 and the storage portion 643 (643a, 643b) into contact with each other. Therefore, the second seal part 64 can prevent the coolant from moving and leaking from the coolant channel 50 (cooling gas channel 226) to the coolant gas channel 55 (cooling gas channel forming part 227). it can. As a result, even when an antifreeze such as ethylene glycol is used as the cooling liquid, the cooling liquid does not reach the membrane electrode assembly 21 from the porous portion 40, and the dissolution of the electrolyte membrane 211 by the alcohol component of the antifreezing liquid is prevented. Can do.

  Further, the sealing characteristic of the second seal portion 64 does not depend on the pressing force, and the reaction force caused by the second seal portion 64 can be reduced. Therefore, the pressing force applied to the electrolyte membrane 211 of the membrane electrode assembly 21 via the cathode separator 22 is reduced, and the electrolyte membrane of the membrane electrode assembly 21 due to the pressing force caused by the second seal portion 64 is prevented. be able to. In addition, since the second seal portion 64 can prevent or suppress the collapse of the diffusion layer 212 due to the pressing force due to the second seal portion 64, it is possible to maintain good diffusibility of the reaction gas. Therefore, the battery life can be extended.

Other examples:
In the above embodiment, both the cathode separator 22 and the anode separator 23 are provided with the porous portion 40, but only the cathode separator 22 may be provided with the porous portion 40. This is because the generated water is generated by the cathode separator 22 and the deterioration of the battery performance is remarkable on the cathode separator 22 side.

In the above embodiment, air is used as the cooling gas, but a fuel gas such as hydrogen may be used. In such a case, humidified hydrogen can be supplied to the anode side, which tends to be dried, without providing a separate humidifier.

  In the above embodiment, the supply mode of the oxidizing gas, the fuel gas, the cooling liquid, and the cooling gas is not described in detail. . As for the fuel gas, when high-pressure fuel gas is used, the supply amount may be adjusted by pressure control without using a pump.

  As described above, the fuel cell according to the present invention has been described based on the embodiments. However, the above-described embodiments of the present invention are for facilitating understanding of the present invention and do not limit the present invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

It is explanatory drawing which shows typically an example of the external appearance structure of the fuel cell which concerns on a 1st Example. It is explanatory drawing which shows typically the structure of the 1st surface (contact surface with a membrane electrode assembly) of the cathode separator which is a component of the fuel cell of a 1st Example. It is explanatory drawing which shows typically the structure of the 2nd surface (cooling flow path side surface) of the cathode separator which is a component of the fuel cell of a 1st Example. It is explanatory drawing which shows typically the structure of the 1st surface (contact surface with a membrane electrode assembly) of the anode separator which is a component of the fuel cell of a 1st Example. FIG. 5 is an explanatory diagram schematically showing a longitudinal section obtained by cutting a part of the fuel cell 10 according to the first embodiment in the longitudinal direction (for example, along line 5-5 in FIG. 2). It is an enlarged view which shows the 2nd seal part 61 in the 1st example typically expanding. It is explanatory drawing which shows typically the 1st modification of the 2nd seal | sticker part in a 1st Example. It is explanatory drawing which shows typically the 2nd modification of the 2nd seal | sticker part in a 1st Example. It is explanatory drawing which shows typically the 1st aspect of the 2nd seal | sticker part in a 2nd Example. It is explanatory drawing which shows typically the 2nd aspect of the 2nd seal | sticker part in a 2nd Example. It is explanatory drawing which shows typically the 3rd aspect of the 2nd seal | sticker part in a 2nd Example. It is explanatory drawing which shows typically the 1st aspect of the 2nd seal | sticker part in a 3rd Example. It is explanatory drawing which shows typically the 2nd aspect of the 2nd seal | sticker part in a 3rd Example. It is explanatory drawing which shows typically the 3rd aspect of the 2nd seal | sticker part in a 3rd Example. It is explanatory drawing which shows typically the 4th aspect of the 2nd seal | sticker part in a 3rd Example. It is explanatory drawing which shows typically the 2nd seal | sticker part in a 4th Example. It is explanatory drawing which shows typically the other aspect of the 2nd seal | sticker part in a 4th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 20 ... Single cell 21 ... Membrane electrode assembly 22 ... Cathode separator 221a ... Oxidation gas supply manifold formation part 221b ... Oxidation gas exhaust manifold formation part 222a ... Fuel gas supply manifold formation part 222b ... Fuel gas exhaust manifold formation part 223a ... Coolant supply manifold forming part 223b ... Coolant discharge manifold forming part 224a ... Cooling gas supply manifold forming part 224b ... Cooling gas exhaust manifold forming part 225 ... Oxidizing gas flow path forming part 226 ... Cooling liquid flow path forming part 227 ... Cooling gas flow path forming portion 22a ... first surface 22b ... second surface 23 ... anode separator 231a ... oxidizing gas supply manifold forming portion 231b ... oxidizing gas exhaust manifold forming portion 232a ... fuel gas supplying manifold forming portion 232b ... fuel gas Exhaust manifold forming portion 233a ... Coolant supply manifold forming portion 233b ... Coolant discharge manifold forming portion 234a ... Cooling gas supply manifold forming portion 234b ... Cooling gas exhaust manifold forming portion 23a ... First surface 23b ... Second surface 235 ... Fuel gas flow path forming part 30 ... End plate 31 ... Tension plate 40 ... Porous part 50 ... Coolant liquid flow path 55 ... Cooling gas flow path 60 ... First seal part 61, 62, 63, 64 ... Second seal 611, 611a, 611b ... Low reaction force sealing material 612, 625 ... Sealing material pool part 613, 621, 623, 624, 631, 633, 635, 637 ... Bead part 614 ... Partition part 615 ... Housing part 622, 632, 634, 636, 638, 642 ... Sealing material 641 ... Opening 643 ... Storage 643 a, 643b ... inner wall surface 644 ... regulating portion 645 ... coolant introduction portion 646 ... cooling gas introduction portion 70 ... rib

Claims (14)

A fuel cell,
A membrane electrode assembly;
A dense portion not allowing liquid permeation and a porous portion allowing liquid permeation, and having a reaction gas flow path forming portion that forms a reaction gas flow path when contacting the membrane electrode assembly. 1 surface, and a second surface having a first coolant flow path forming portion formed in the dense portion and a first cooling gas flow path forming portion formed in the porous portion. A first separator;
A first surface having a reaction gas flow path forming part that forms a reaction gas flow path when abutting against the membrane electrode assembly, a second coolant flow path forming part, and a second cooling gas flow A unit cell comprising: a second separator comprising a second surface having a path forming part;
When the unit cells are stacked and the second surface of the first separator and the second surface of the second separator are combined,
A first seal portion disposed between an outer edge portion of the second surface of the first separator and an outer edge portion of the second surface of the second separator;
Formed by the first cooling liquid flow path forming portion and the second cooling liquid flow path forming portion, a cooling liquid flow path through which the cooling liquid flows, the first cooling gas flow path forming portion, and the A second cooling gas flow path forming section and a cooling gas flow path through which cooling gas flows, and a second reaction force generated lower than that of the first seal section. A fuel cell comprising a seal portion. The fuel cell according to claim 1, wherein
The first seal portion is a first seal material;
The fuel cell, wherein the second seal portion is a second seal material having a lower reaction force characteristic than the first seal material. The fuel cell according to claim 1, wherein
The second seal portion includes a first holding portion formed on the second surface of the first separator and a second holding portion formed on the second surface of the second separator. Part and a sealing material sandwiched between the first sandwiching part and the second sandwiching part,
A fuel cell in which a sealing distance increasing portion is formed on a clamping surface of the first clamping unit and a clamping surface of the second clamping unit. The fuel cell according to claim 3, wherein
The sealing distance increasing portion is a fuel cell that is a plurality of uneven portions. The fuel cell according to claim 4, wherein
The depth of at least one recess among the plurality of recesses and projections is a fuel cell deeper than the depth of other recesses. The fuel cell according to claim 1, wherein
The second seal portion includes a first clamping portion formed on the second surface of the first separator, and a second clamping portion formed on the second surface of the second separator. And a sealing material sandwiched between the first and second sandwiching portions,
The fuel cell in which the clamping surfaces of the first and second clamping parts and the sealing material are modified with predetermined functional groups. The fuel cell according to claim 1, wherein
The second seal portion includes a first second seal portion forming portion formed on the second surface of the first separator and a second surface formed on the second surface of the second separator. Two second seal portion forming portions and a substantially U-shaped opening, and the first and second second seal portion forming portions are substantially U-shaped with respect to the coolant flow path. A fuel cell formed by a sealing material arranged with an opening directed. The fuel cell according to claim 7, wherein
The sealing material further includes a substantially U-shaped opening directed to the cooling gas flow path. The fuel cell according to any one of claims 1 to 8,
The second separator includes a dense portion that does not allow liquid permeation and a porous portion that allows liquid permeation, and the second coolant flow path forming portion is formed in the dense portion, The second cooling gas flow path forming part is a fuel cell formed in the porous part. The fuel cell according to any one of claims 1 to 9,
A fuel cell, wherein a downstream end of the cooling gas channel is in communication with a reaction gas channel formed by the first separator and a membrane electrode assembly. The fuel cell according to claim 10, wherein
The first separator is a cathode-side separator;
The second separator is an anode-side separator;
The fuel cell, wherein the cooling gas is air as an oxidizing gas. The fuel cell according to any one of claims 1 to 11,
The fuel cell, wherein the coolant is an aqueous ethylene glycol solution. A plurality of unit cells each provided with a pair of separators, each of which includes at least one dense part that does not allow liquid permeation and a porous part that allows liquid permeation, and a membrane electrode assembly sandwiched between the pair of separators A stacked fuel cell,
In the adjacent part of each unit cell,
A coolant flow path formed in a portion corresponding to the dense portion and through which the coolant flows;
A cooling gas passage formed in a portion corresponding to the porous portion;
A first seal portion disposed on the outer edge portion;
A second liquid gas is disposed between the cooling liquid flow path and the cooling gas flow path, separates the cooling liquid flow path and the cooling gas flow path, and has a lower reaction force against stress than the first seal portion. A fuel cell. The fuel cell according to claim 13, wherein
The fuel cell, wherein the coolant is an aqueous ethylene glycol solution.

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