JP4635465B2 - Fuel cell and gas separator for fuel cell - Google Patents

Description

  The present invention relates to a fuel cell and a fuel cell gas separator.

  In the fuel cell, water is generated at the cathode as the electrochemical reaction proceeds, and the generated water is vaporized into the oxidizing gas supplied to and discharged from the cathode. Therefore, in the oxidizing gas flow path, the generated water is positively removed from the oxidizing gas flow path in order to prevent inconveniences such as generation water condensing and preventing the flow of the oxidizing gas. It is desirable to provide a configuration. Note that the problem of condensed water does not occur only in the oxidizing gas flow path, but also in the fuel gas flow path supplied to the anode, the water vapor mixed from the oxidizing gas flow path side through the electrolyte layer or the fuel in advance This is a problem that may occur due to water vapor contained in the gas. Thus, the problem of the condensed water is a problem common to the flow path of the reaction gas used for the electrochemical reaction.

  In Patent Document 1, a through-hole penetrating a gas separator disposed between stacked single cells is sealed with a water-permeable resin, and a channel formed between the gas separator and the electrode is defined as an oxidizing gas channel. Thus, a configuration that enables discharge of water from the oxidizing gas via the water-permeable resin is disclosed. If the gas channel adjacent to the oxidizing gas channel via the gas separator is a fuel gas channel, the fuel gas can be humidified using moisture in the oxidizing gas. Further, if the gas channel adjacent to the oxidizing gas channel through the gas separator is a channel through which the oxidizing gas before being introduced into the oxidizing gas channel flows, the moisture in the oxidizing gas is used to oxidize the gas channel. The oxidizing gas before being introduced into the gas flow path can be humidified.

JP-A-9-283157 Japanese National Patent Publication No. 11-508726

  However, according to the configuration of Patent Document 1 described above, the efficiency of discharging the generated water generated at the cathode to the cooling water flow path via the water-permeable resin is affected by the flow rate of the oxidizing gas supplied to the fuel cell. In some cases, the water discharge efficiency is insufficient.

  The present invention has been made to solve the above-described conventional problems. In a fuel cell, when water in a gas flow path is discharged through a gas separator, the efficiency of water discharge is improved. Objective.

In order to achieve the above object, the first fuel cell of the present invention comprises:
An electrolyte layer;
Adjacent the electrode between the electrolyte layer,
Having a first surface that forms a reaction gas flow path through which a reaction gas used in an electrochemical reaction flows, and a second surface that forms a cooling gas flow path through which a cooling gas flows;
A dense region comprising a substrate made of gas-impermeable dense member, and a porous region provided so as to contact between the cooling gas flow path and the reaction gas channel possess,
In the first surface, as the reaction gas flow path, a gas separator that forms a flow path in which a flow path formed in the dense area and a flow path formed in the porous area are continuously formed ;
In addition,
The reaction gas flow path formed in the porous region suppresses the movement of moisture in the flow direction of the reaction gas due to the flow of the reaction gas, compared to the reaction gas flow channel formed in the dense region. and a water discharge suppression unit, wherein the porous flow rate of the reaction gas in the reaction gas flow paths formed in the region, compared to the flow velocity of the reaction gas in the reaction gas channel formed in the dense region The gist is to provide a flow velocity lowering portion to be reduced .

According to the first fuel cell of the present invention configured as described above, in the reaction gas flow path formed in the porous region, the flow of the reaction gas compared to the reaction gas flow channel formed in the dense region. Since the movement of moisture in the gas flow direction due to is suppressed, moisture tends to stay in the reaction gas flow path in the porous region. Therefore, it is possible to improve the efficiency of moisture transfer from the reaction gas channel to the cooling gas channel via the porous region. At this time, by reducing the flow rate of the reaction gas in the reaction gas flow path as compared with the dense region in the porous region, the movement of moisture in the gas flow direction due to the flow of the reaction gas in the porous region is reduced in the dense region. Can be suppressed compared to.

In such a first fuel cell of the present invention, the flow velocity reduction portion is in the porous region having a channel cross-section formed larger than the channel cross-section of the reaction gas channel formed in the dense region. The reaction gas flow path may be used.

  In this way, the reaction gas flow path in the porous region has a larger cross-sectional area than the reaction gas flow path in the dense region, so that the flow velocity of the reaction gas in the porous region is larger than that in the dense region. Can be reduced.

In such a first fuel cell of the present invention,
The gas separator has a recess for forming the gas flow path over the dense region and the porous region on the first surface,
The flow velocity reduction portion may be the reaction gas flow path formed by the concave portion provided in the porous region that is formed deeper than the concave portion provided in the dense region.

  According to such a configuration, it is possible to easily realize a configuration in which the reaction gas channel formed in the porous region has a larger channel cross-sectional area than the reaction gas channel formed in the dense region. .

The second fuel cell of the present invention comprises:
A fuel cell,
An electrolyte layer;
Adjacent the electrode between the electrolyte layer,
Having a first surface that forms a reaction gas flow path through which a reaction gas used in an electrochemical reaction flows, and a second surface that forms a cooling gas flow path through which a cooling gas flows;
A dense region comprising a base material composed of a gas-impermeable dense member, and a porous region provided so as to communicate between the reaction gas channel and the cooling gas channel;
In the first surface, as the reaction gas flow path, a gas separator that forms a flow path in which a flow path formed in the dense area and a flow path formed in the porous area are continuously formed;
In addition,
The reaction gas flow path formed in the porous region suppresses the movement of moisture in the flow direction of the reaction gas due to the flow of the reaction gas, compared to the reaction gas flow channel formed in the dense region. The gist of the present invention is to provide a gas flow obstructing unit that prevents the flow of the reaction gas toward a predetermined direction in the reaction gas flow path formed in the porous region as the moisture discharge suppressing unit .

  With such a configuration, by preventing the flow of the reaction gas in a predetermined direction, the movement of moisture in the gas flow direction due to the flow of the reaction gas is prevented, and the discharge of moisture from the reaction gas flow path is suppressed. Can do. Further, by preventing the flow of the reaction gas toward the predetermined direction, the flow of the reaction gas can be stirred in the reaction gas flow path, and the gas utilization rate during power generation can be improved.

In such a second fuel cell of the present invention,
The gas separator has a concave portion for forming the reaction gas flow channel in the dense region on the first surface, and the reaction gas flow channel is formed in the porous region to form an interior. A porous portion through which the reaction gas passes;
The gas flow obstructing part may be the porous part provided continuously to the concave part.

  In such a case, the reaction gas that has passed through the reaction gas flow path formed by the recess flows in the porous portion, thereby preventing the reaction gas flow, and moisture in the gas flow direction due to the reaction gas flow. Movement is suppressed.

In the first or second fuel cell of the present invention,
It is good also as a connection channel which connects the cooling gas channel and the reaction gas channel, and guides the cooling gas which passed through the cooling gas channel to the reaction gas channel as the reaction gas.

  In such a configuration, the same kind of gas as the reaction gas is used as the cooling gas. Therefore, even if the reaction gas and the cooling gas may be mixed through the porous region, different types of gas are mixed. There is no inconvenience caused by doing this. Moreover, according to the said structure, the reaction gas used for an electrochemical reaction can be humidified by letting a cooling gas flow path pass beforehand. Therefore, when the present invention is applied to a polymer electrolyte fuel cell, it is possible to prevent the electrolyte membrane from drying in the region near the inflow portion where the reaction gas flows. As a result, it is possible to eliminate the need for a device for humidifying the reaction gas supplied to the fuel cell, and to reduce the size of the humidifier.

In the first or second fuel cell of the present invention, the reaction gas may be an oxidizing gas containing oxygen. With such a configuration, moisture can be efficiently discharged from the flow path through which the oxidizing gas containing the generated water generated at the cathode flows through the porous region.

In the first or second fuel cell of the present invention, the porous region may form the reaction gas channel downstream of the reaction gas channel formed in the dense region. . When water is vaporized in the reaction gas flowing through the reaction gas channel, the amount of water in the reaction gas channel increases toward the downstream of the reaction gas channel. Therefore, by providing the porous region in the region where the water content is increased, the efficiency of drainage from the reaction gas channel through the porous region can be improved.

The first or second fuel cell of the present invention further includes
In the porous region, the region corresponding to the downstream side of the cooling gas channel corresponds to the upstream side of the cooling gas channel as a moisture retention preventing part for preventing the retention of moisture in the reaction gas channel. It is good also as providing the said reactive gas flow path in which the flow-path cross-sectional area was formed small compared with the said reactive gas flow path formed in the area | region .

  In the cooling gas channel, moisture is supplied from the reaction gas channel side through the porous region, so that the amount of moisture contained in the cooling gas increases toward the downstream side, and the porous region decreases toward the downstream side of the cooling gas channel. The efficiency of moisture transfer from the reaction gas channel to the cooling gas channel is reduced. Therefore, with the above-described configuration, it is possible to prevent inconvenience caused by moisture remaining in a region corresponding to the downstream side of the cooling gas channel having a low moisture transfer efficiency in the reaction gas channel.

At this time, in the above configuration, in the region corresponding to the downstream side of the cooling gas channel, the flow rate of the reactive gas is higher than that in the region corresponding to the upstream side of the cooling gas channel. Moisture retention can be prevented.

In the first or second fuel cell of the present invention,
The cooling gas flow path is formed in the porous region on the second surface of the gas separator,
The fuel cell further includes:
The cooling gas as a moisture movement promoting part that promotes the movement of moisture from the reaction gas channel to the cooling gas channel via the porous region on the downstream side compared to the upstream side of the cooling gas channel. A cooling gas flow rate adjusting unit that increases the flow rate of the cooling gas on the downstream side of the upstream side of the flow path may be provided.

  With such a configuration, the amount of moisture contained in the cooling gas increases, and on the downstream side of the cooling gas passage where the moisture transfer efficiency from the reaction gas passage through the porous region to the cooling gas passage decreases, Since the moisture movement is promoted, the efficiency of moisture movement can be improved in the entire porous region.

In addition, since the boundary layer becomes thinner by increasing the flow velocity of the cooling gas at the downstream side of the cooling gas channel than at the upstream side, the vaporization of moisture from the porous body to the cooling gas channel is promoted, The efficiency of movement can be improved. Such a cooling gas flow rate adjusting unit can be realized, for example, by reducing the flow path cross-sectional area in the cooling gas flow direction of the cooling gas flow path on the downstream side of the upstream side of the cooling gas flow path.

Alternatively, in the first or second fuel cell of the present invention, the cooling gas flow path is formed in the porous region on the second surface of the gas separator , The cooling gas as a moisture movement promoting part that promotes the movement of moisture from the reaction gas channel to the cooling gas channel via the porous region on the downstream side compared to the upstream side of the cooling gas channel. A porous region having a larger pore diameter and / or porosity than the region forming the upstream side in the region forming the downstream side of the flow path may be provided as the porous region . Even with such a configuration, moisture movement can be promoted on the downstream side of the cooling gas flow path.

Alternatively, in the first or second fuel cell of the present invention, the cooling gas flow path is formed in the porous region on the second surface of the gas separator, Furthermore, as a moisture movement promoting part that promotes the movement of moisture from the reaction gas channel to the cooling gas channel via the porous region on the downstream side compared to the upstream side of the cooling gas channel, A cooling gas flow path forming section that forms the cooling gas flow path on the second surface of the gas separator and that forms the cooling gas flow path with a larger flow area on the downstream side than on the upstream side. provided may be Rukoto. As described above, it is also possible to promote moisture movement on the downstream side of the cooling gas channel by increasing the channel surface area of the cooling gas channel on the downstream side.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in the form of a fuel cell gas separator, a method of humidifying a reaction gas in a fuel cell, or the like.

A. First embodiment:
A-1. Overall configuration of the device:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell according to a first embodiment of the present invention. The fuel cell of the present embodiment includes a fuel cell stack 60 that is a main body of power generation, a fuel gas supply unit 62, a blower 64, a coolant circulation unit 61, and a control unit 68. The fuel cell of the present embodiment is characterized by the internal configuration of the fuel cell stack 60. First, the overall configuration will be described with reference to FIG.

  The fuel cell stack 60 (hereinafter referred to as the stack 60) is a polymer electrolyte fuel cell, and includes a plurality of stacked single cells. A plurality of fluid flow paths are provided inside the stack 60. Specifically, in the stack 60, a fuel gas passage 70 that is a passage for a fuel gas containing hydrogen, an oxidizing gas passage 72 that is a passage for an oxidizing gas containing oxygen, and a cooling gas passage A cooling gas flow path 74 that is a flow path and a cooling liquid flow path 76 that is a flow path of the cooling liquid are provided.

  The fuel gas supply unit 62 is a device for supplying fuel gas to the fuel gas flow path 70 of the stack 60. The fuel gas supply unit 62 can be provided with, for example, a hydrogen tank or a hydrogen cylinder including a hydrogen storage alloy. In this case, high-purity hydrogen gas can be supplied to the stack 60 as a fuel gas. Alternatively, a reformer may be provided as the fuel gas supply unit 62, and a hydrogen-rich reformed gas obtained by reforming a hydrocarbon fuel may be supplied to the stack 60 as a fuel gas. The fuel gas supplied to the stack 60 is subjected to an electrochemical reaction while passing through the fuel gas flow path 70, and the remaining anode off gas is discharged to the outside of the stack 60.

  The blower 64 is a device for supplying air to the cooling gas channel 74 and the oxidizing gas channel 72 of the stack 60. That is, in the fuel cell of this embodiment, the air supplied from the blower 64 is used as a cooling gas for cooling the stack 60 and as an oxidizing gas. An air flow path 80 is provided by connecting the blower 64 and the stack 60, and the air supplied to the stack 60 via the air flow path 80 first cools the stack 60 while passing through the cooling gas flow path 74. To do. A connection flow path 82 is provided by connecting the cooling gas flow path 74 and the oxidizing gas flow path 72, and the air that has passed through the cooling gas flow path 74 is transferred to the oxidation gas flow path 72 via the connection flow path 82. Guided and subjected to electrochemical reaction. The remaining cathode off gas is discharged outside the stack 60. A branch channel 84 is provided by branching from the air channel 80, and the branch channel 84 guides air to the connection channel 82 without passing through the cooling gas channel 74. The branch flow path 84 is provided with a flow rate adjusting valve 63 for adjusting the amount of air passing through the branch flow path 84. Therefore, by controlling the blower 64 and the flow rate adjustment valve 63, the amount of air passing through the cooling gas passage 74 and the amount of air used for the electrochemical reaction can be adjusted.

  The coolant circulation unit 61 includes a circulation pump 65 and a heat exchanger 66. The circulation pump 65 circulates a coolant for cooling the stack 60 between the coolant flow path 76 in the stack 60 and the heat exchanger 66. The coolant is heated by exchanging heat with the stack 60 while passing through the coolant flow path 76, and the cooled coolant is cooled by passing through the heat exchanger 66.

  The control unit 68 is configured as a microcomputer including a CPU, a ROM, a RAM, a timer, and the like. The control unit 68 acquires information regarding the amount of power to be generated by the fuel cell, and acquires information regarding the state of each unit of the fuel cell. Further, the control unit 68 outputs a drive signal to each part of the fuel cell, such as the fuel gas supply unit 62, the blower 64, the circulation pump 65, and the flow rate adjustment valve 63, based on the acquired information.

A-2. Stack 60 configuration:
FIG. 2 is an exploded perspective view showing the configuration of the single cell 10 constituting the fuel cell of the present embodiment. FIG. 3 is a plan view showing a state of the separator 20 constituting the single cell 10.

  As shown in FIG. 2, the unit cell 10 has a membrane-electrode assembly (MEA) 12 sandwiched between gas diffusion layers 13 and 14, and the MEA 12 and the gas diffusion layers 13 and 14 are further sandwiched from both sides. The gas diffusion layer 13 is not shown in FIG. 2 (see FIGS. 5 to 7).

  The MEA 12 is obtained by forming a catalyst layer on both sides of the solid polymer electrolyte membrane. The solid polymer electrolyte membrane is a proton conductive ion exchange membrane formed of, for example, a fluororesin, and exhibits good ion conductivity in a wet state. The catalyst layer is a layer having platinum as a catalyst or an alloy made of platinum and another metal. The gas diffusion layers 13 and 14 can be formed of a gas diffusible conductive member, for example, carbon cloth or carbon paper woven with a yarn made of carbon fiber, or foam metal or metal mesh.

  Between the separators 20 and 22 and the MEA 12 sandwiched between the gas diffusion layers, a reaction gas flow path for an electrochemical reaction is formed. That is, an in-single cell oxidizing gas passage through which an oxidizing gas containing oxygen such as air passes is formed between the separator 20 and the MEA 12 including the gas diffusion layer 13. Further, between the separator 22 and the MEA 12 including the gas diffusion layer 14, an in-single cell fuel gas flow path through which hydrogen-containing fuel gas passes is formed. Further, between the separator 20 constituting one single cell 10 and the separator 22 constituting the adjacent single cell 10, there is an inter-cell coolant flow path through which the coolant passes, and between the cells through which the cooling gas passes. A cooling gas flow path is formed. As described above, in the fuel cell of this embodiment, the inter-cell coolant flow path and the inter-cell cooling gas flow path are formed between all adjacent single cells. It may be formed every time. The separators 20 and 22 are made of a conductive material such as carbon or metal, and include a dense body that does not allow gas and moisture to permeate, and a porous body that allows permeation of moisture (liquid water or water vapor). The arrangement and configuration of the porous body correspond to the main part of the present invention and will be described in detail later.

  3A and 3B are plan views showing a state in which the separator 20 is viewed from each of the two surfaces. FIG. 3A shows a surface that is visible on the near side in the separator 20 shown in FIG. As shown in FIG. 3, the separator 20 has eight holes near its outer periphery. Specifically, it has holes 22a, 22b, 24a, 24b, 26a, 26b, 28a, 28b. As shown in FIG. 2, holes similar to the above eight holes are also provided at corresponding positions of the separator 22, and the holes provided at the corresponding positions overlap in the stack 60. A fluid flow path (manifold) that penetrates the stack 60 in the stacking direction of the single cells 10 is formed.

One side of the separator 20 communicates with the hole 22a and the hole 22b, and forms an oxidizing gas flow path 30 in the single cell between the MEA 12 including the gas diffusion layer 13 and the oxidizing gas flow path forming part 30. (See FIG. 3A). Further, the other surface of the separator 20 is connected to the hole portion 26a and the hole portion 26b, and a coolant flow path forming portion that forms an inter-cell coolant flow path between the separator 20 and the adjacent separator 22 is provided. 32 is provided. The other surface further has a cooling gas flow path forming portion 34 that communicates the hole 28a and the hole 28b and forms an inter-cell cooling gas flow path between the separator 20 and the adjacent separator 22. (See FIG. 3B).

  The air passing through the connection channel 82 is distributed to the oxidizing gas channel in the single cell in each single cell 10 via the oxidizing gas supply manifold (hole 22a), and the cathode off-gas is supplied to the oxidizing gas discharge manifold (hole). Unit 22b) and led outside the stack 60. The coolant supplied to the stack 60 is distributed to the inter-cell coolant flow paths via the coolant supply manifold (holes 26a), and gathers in the coolant discharge manifold (holes 26b). Guided outside. The air supplied to the stack 60 is distributed to the inter-cell cooling gas flow paths via the cooling gas supply manifold (holes 28a), and gathers in the cooling gas discharge manifold (holes 28b) to be connected to the connection flow paths. 82. In FIG. 3, the direction of the flow of each fluid is indicated by arrows.

  The separator 22 has a cooling liquid flow path forming section 33 having a shape corresponding to the cooling liquid flow path forming section 32 and a cooling gas flow having a shape corresponding to the cooling gas flow path forming section 34 on one surface in contact with the separator 20. A path forming portion 35 is formed (see FIG. 2). The cooling liquid flow path forming unit 33 forms an inter-cell cooling liquid flow path together with the adjacent cooling liquid flow path forming part 32, and the cooling gas flow path forming part 35 together with the adjacent cooling gas flow path forming part 34 A cooling gas flow path is formed. In addition, the other surface of the separator 22 communicates with the hole 24a and the hole 24b, and forms a fuel gas flow path in the single cell between the MEA 12 including the gas diffusion layer 14. Are provided (not shown). The fuel gas supplied to the stack 60 is distributed to the fuel gas flow path in the single cell formed in each single cell 10 via the fuel gas supply manifold (hole 24a), and the anode off-gas is discharged from the fuel gas. Collected in the manifold (hole 24b) and guided outside the stack 60.

  In FIG. 1, the entire flow path formed continuously including the manifold in the stack 60 is represented as an oxidizing gas flow path 72, a cooling liquid flow path 76, a gas flow path 74, or a fuel gas flow path 70. Yes.

  Here, in FIGS. 2 and 3, the oxidizing gas flow path forming portion 30 is represented as a concave portion having a flat bottom surface, but the oxidizing gas flow path forming portion 30 and the fuel gas flow path forming portion have predetermined irregularities. It may have a shape. As shown in FIG. 4, the oxidant gas flow path forming part 30 of the present embodiment has a plurality of substantially parallel elongated protrusions 36, and a plurality of substantially parallel groove-shaped flows as oxidant gas flow paths in a single cell. A road group is formed. Alternatively, the oxidizing gas flow path forming portion 30 and the fuel gas flow path forming portion are provided with a plurality of convex portions protruding from the bottom surface of the concave portion, or formed as a concave portion having a flat bottom surface, and gas diffusion into the concave portion The gas flow path may be formed by fitting the layer. Similarly, the cooling gas flow path forming portion 34 may be provided with a predetermined uneven shape.

  5 and 6 are cross-sectional views schematically showing the internal configuration of the single cell 10. 5 shows a state of a cross section corresponding to the 5-5 cross section in the separator 20 shown in FIG. 4, and FIG. 6 shows a state of a cross section corresponding to the 6-6 cross section in the separator 20 shown in FIG. Yes. Both FIG. 5 and FIG. 6 represent a cross section that is parallel to the convex portion 36 and does not include the convex portion 36.

  The separator 20 includes a porous portion 52 formed of a porous body. The porous portion 52 is provided so as to penetrate the separator 20 so as to connect the oxidizing gas channel in the single cell and the cooling gas channel. In the separator 20, a portion other than the porous portion 52 (hereinafter referred to as a separator base portion) is formed of a dense member that is impermeable to moisture and gas. For example, the separator base can be formed of dense carbon obtained by compression molding a carbon powder mixed with a binder, or a press-molded metal plate. The porous portion 52 is preferably formed of the same kind of material as the member constituting the separator base. For example, when the separator base is made of carbon, the porous portion 52 is preferably made of carbon. A carbon porous body can be made into a desired porosity by selecting suitably the shape and size of the carbon powder to be used, or a mixing ratio with a binder. When the separator base is made of metal, the porous portion 52 may be formed of a metal porous body such as a sintered metal or a metal mesh. The separator base portion and the porous portion 52 may be integrally formed, or may be combined with each other after being formed separately.

  In the separator 20, the porous portion 52 formed by the porous body is disposed over the entire region where the cooling gas flow path forming portion 34 is formed. Here, FIGS. 5 and 6 show a state in which the cooling gas flow path forming portion 34 has an uneven shape including a plurality of parallel grooves having the same width. In FIG. 2 and FIG. 3, the region where the porous portion 52 is disposed in the separator 20 is surrounded by a broken line as the porous region 53. In the following description, not only the region where the porous portion 52 is disposed in the separator 20 but also the region corresponding to the region where the porous portion 52 is disposed in the entire stack 60 is referred to as a porous region 53. In the stack 60, a region corresponding to a region where the separator base is disposed and other than the porous region 53 is referred to as a dense region.

  FIGS. 5 and 6 show a state in which the oxidizing gas channel 40 in the single cell is formed between the MEA 12 including the gas diffusion layer 13 and the surface of the separator 20 in the oxidizing gas channel forming unit 30. Yes. 5 and 6, the oxidizing gas supply manifold 44 is formed by the holes 22a provided in the separators 20, 22, and the oxidizing gas discharge manifold 46 is formed by the holes 22b provided in the separators 20, 22. Is shown communicating with the oxidizing gas flow path 40 in the single cell. The porous region 53 in which the porous portion 52 is disposed is a downstream region in the single-cell oxidizing gas flow channel 40, that is, in the vicinity of a connection portion with the oxidizing gas discharge manifold 46 in the single-cell oxidizing gas flow channel 40. It is an area.

  As shown in FIGS. 5 and 6, in the single cell 10, the depth of the oxidizing gas flow path 40 in the single cell is divided into the porous region 53 that is the downstream region of the oxidizing gas flow and the dense region that is the upstream region. The depth of the groove formed between the convex portions 36 is different. 5 and 6, the depth of the oxidizing gas channel 40 in the single cell in the dense region is “a”, and the depth of the oxidizing gas channel 40 in the single cell in the porous region 53 is “b” or “c”. However, a <b and a <c hold. Furthermore, also in the porous region 53, the depth of the oxidizing gas flow path 40 in the single cell differs depending on the location, and b> c is established. That is, the porous region 53 of the separator 20 is provided with a region for forming a deeper in-single cell oxidizing gas flow channel and a region for forming a shallower in-single cell oxidizing gas flow channel. The region where the deeper single-cell oxidizing gas flow path 40 is formed is a half region of the porous region 53 than the hole 28a (cooling gas supply manifold), and is hereinafter referred to as a cooling gas upstream region 50. Further, the region where the shallower single-cell oxidizing gas flow path 40 is formed is a half region of the porous region 53 from the hole 28b (cooling gas discharge manifold), and is hereinafter referred to as a cooling gas downstream region 54 ( (See FIG. 3A). In FIG. 3A, the porous region 53 is divided into two equal parts to provide the cooling gas upstream region 50 and the cooling gas downstream region 54. In this embodiment and the embodiments described later, the cooling gas upstream region is provided. The region 50 and the cooling gas downstream region 54 do not necessarily have the same size. As shown in FIG. 4, the oxidizing gas flow path 40 in the single cell formed by the separator 20 is a parallel groove-shaped flow path having the same width. (The gas flow rate per unit channel cross-sectional area is small). That is, the porous region 53 has a larger cross-sectional area of the oxidizing gas flow channel in the single cell than the dense region, and the cooling gas upstream region 50 is more in the porous region 53 than the cooling gas downstream region 54. Also, the channel cross-sectional area of the oxidizing gas channel in the single cell is large.

  FIG. 7 shows a cross section including the convex portion 36 that is parallel to the 5-5 cross section and the 6-6 cross section shown in FIG. Thus, the cross section including the convex portion 36 shows a common structure regardless of whether it is the cooling gas upstream region 50 or the cooling gas downstream region 54. That is, the convex portion 36 in contact with the gas diffusion layer 13 is formed by the separator base portion in the dense region, and the porous portion 52 is formed in the porous region 53.

  5 and 6, the fuel gas flow path 42 in the single cell is formed between the MEA 12 including the gas diffusion layer 14 and the surface of the separator 22 in the fuel gas flow path forming portion of the separator 22. It is shown. In the separator 22, a predetermined uneven shape corresponding to the shape of the cooling gas flow path forming portion 35 and the cooling liquid flow path forming portion 33 is provided on the surface opposite to the surface facing the MEA 12, similarly to the separator 20. ing. The separator 22 of this embodiment is entirely formed of a dense member similar to the separator base of the separator 20. As shown in FIGS. 5 and 6, in the separator base portion of the separator 20, a sealing member 38 such as an O-ring is disposed around the cooling gas flow path forming portion 34 and the cooling liquid flow path forming portion 32. The inter-cell cooling gas flow path and the inter-cell cooling liquid flow path are sealed.

A-3. Moisture transfer behavior:
In a fuel cell, water is generated at the cathode as the electrochemical reaction proceeds. In the fuel cell according to the present embodiment, the separator 20 is provided with the porous portion 52 in the region corresponding to the downstream side of the single-cell oxidizing gas flow path 40, so that the oxidizing gas in the single cell is provided via the porous portion 52. The water in the flow path 40 can be discharged to the inter-cell cooling gas flow path. Here, when the amount of water in the oxidizing gas passing through the single-cell oxidizing gas channel 40 is lower than the saturated vapor pressure, the cooling gas flow from the single-cell oxidizing gas channel 40 through the porous portion 52 is performed. Moisture moving to the road moves in the state of water vapor. On the other hand, when the amount of water in the oxidizing gas passing through the single-cell oxidizing gas channel 40 is large and the water condenses, the porous portion 52 once absorbs the condensed water, and then the porous Moisture is transferred by vaporizing from the portion 52 into the cooling gas flow path.

  In the fuel cell of this embodiment, the condensed water in the single-cell oxidizing gas channel 40 is easily taken into the porous portion 52 by the capillary suction force and moves to the inter-cell cooling gas channel side. Further, when the condensed water is absorbed in the porous portion 52 in this way, the porous portion 52 is gas-sealed by absorbing the condensed water, and the single-cell oxidizing gas flow path 40 and the inter-cell cooling gas flow are Gas mixing with the road is suppressed. In order to promote such moisture uptake from the oxidizing gas and moisture transfer to the inter-cell cooling gas flow path side, the porous portion 52 is desirably subjected to a hydrophilic treatment to increase the hydrophilicity. For example, when the porous portion 52 is formed of a carbon porous body, the carbon porous body is boiled in hydrogen peroxide water to introduce hydroxyl groups (—OH groups) on the carbon surface. It is possible to easily impart hydrophilicity.

  In the fuel cell of the present embodiment, the cross-sectional area of the oxidizing gas channel 40 in the single cell formed in the porous region 53 is the sectional area of the oxidizing gas channel 40 in the single cell formed in the dense region. The oxidizing gas flow path forming part 30 of the separator 20 is formed so as to be larger than that. As a result, the flow rate of the oxidizing gas passing through the single-cell oxidizing gas flow path 40 is slower when passing through the porous region 53 on the downstream side than when passing through the dense region on the upstream side. . The slower the flow rate of the oxidizing gas, the more the operation of discharging the liquid water in the oxidizing gas channel 40 in the single cell to the outside by the flow of the oxidizing gas is suppressed. Further, the slower the flow rate of the oxidizing gas, the lower the efficiency with which the generated water generated at the cathode is vaporized into the oxidizing gas. Therefore, the lower the flow rate of the oxidizing gas, the easier the moisture stays in the oxidizing gas flow path 40 in the single cell. As described above, the oxidizing gas flow channel in the single cell in the porous region 53 formed deeper than the oxidizing gas flow channel in the single cell formed in the dense region has moisture in the gas flow direction due to the flow of the oxidizing gas. Functions as a moisture discharge suppression unit that suppresses the movement of the gas by the shape of the oxidizing gas flow path in the single cell.

  As described above, according to the fuel cell of the present embodiment, in the porous region 53, the movement of moisture in the gas flow direction due to the flow of the oxidizing gas is suppressed compared to the dense region. Therefore, in the porous region 53, more moisture remains in the single-cell oxidizing gas flow channel 40, and more of the moisture in the single-cell oxidizing gas flow channel 40 passes through the porous portion 52. It becomes possible to move to the cooling gas flow path side. Therefore, it is possible to improve the moisture transfer efficiency from the oxidizing gas flow channel 40 in the single cell to the cooling gas flow channel side through the porous portion 52. In particular, in this embodiment, since the cooling gas that has passed through the inter-cell cooling gas flow path is used as the oxidizing gas, by improving the moisture transfer efficiency from the single-cell oxidizing gas flow path 40 to the cooling gas flow path, It becomes possible to make the humidity of the oxidizing gas supplied to the oxidizing gas flow path 40 in the single cell higher. Therefore, it is possible to prevent water shortage in the electrolyte membrane.

Further, in the fuel cell of the present embodiment, in the porous region 53, the single-cell oxidizing gas flow path 40 formed in the cooling gas downstream region 54 is more oxidized in the single cell formed in the cooling gas upstream region 50. Compared to the gas flow path 40, the flow path cross-sectional area is formed smaller. Thereby, the flow rate of the oxidizing gas passing through the cooling gas downstream region 54 is higher than that of the oxidizing gas passing through the cooling gas upstream region 50. By making the flow rate of the oxidizing gas faster, the efficiency of moving the moisture in the gas flow direction by the flow of the oxidizing gas in the downstream region of the cooling gas in the single-cell oxidizing gas flow path is higher than in the upstream region of the cooling gas. improves. As described above, in this embodiment, the oxidizing gas flow path in the single cell in the downstream region of the cooling gas formed shallower than the upstream region of the cooling gas moves the moisture by the flow of the oxidizing gas and prevents the moisture from staying. Functions as a moisture retention prevention unit. Here, since the cooling gas passing through the inter-cell cooling gas flow path is humidified by the moisture supplied from the oxidizing gas flow path 40 in the single cell via the porous portion 52, the cooling gas downstream of the inter-cell cooling gas flow path. The humidity of the cooling gas increases toward the side. The higher the humidity of the cooling gas, the lower the efficiency of moisture transfer from the intra-single cell oxidizing gas flow channel 40 to the inter-cell cooling gas flow channel via the porous portion 52. The cooling gas downstream region 54 in which the flow path cross-sectional area is reduced and the flow rate of the oxidizing gas is increased is thus a region where the efficiency of moisture movement through the porous portion 52 is low.

  As described above, according to the fuel cell of this example, the porous region 53 as a whole improves the efficiency of moisture movement through the porous portion 52 and compares the efficiency of moisture movement within the porous region 53. It is possible to prevent a decrease in battery performance due to flooding occurring in a part of the region that becomes bad.

B. Second embodiment:
In the first embodiment, as a moisture discharge suppressing portion that suppresses the movement of moisture in the gas flow direction due to the flow of oxidizing gas, the oxidizing gas in the single cell in which the flow path is formed deeper in the porous region 53 than in the dense region. Although the flow path 40 is provided, a different configuration may be used. Hereinafter, as a second embodiment, a description will be given of a fuel cell having a cross-sectional area of the porous region 53 that is larger than that of the dense region and having an in-single cell oxidizing gas flow channel having a shape different from that of the first embodiment. To do. Since the fuel cell of the second embodiment has a configuration similar to that of the fuel cell of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different configurations are described.

  FIG. 8 is a plan view showing the configuration of the separator 120 included in the fuel cell of the second embodiment. The separator 120 is used in place of the separator 20 of the first embodiment, and an oxidizing gas flow path forming unit 130 for forming an oxidizing gas flow path in the single cell is provided between the separator 120 and the MEA 12. In the dense region, the oxidizing gas flow path forming portion 130 has a plurality of elongated convex portions 136 for forming a plurality of groove-shaped flow channel groups substantially parallel to the convex portion 36 of the first embodiment. Yes. Further, the oxidizing gas flow path forming part 130 is a convex part having a square cross section in the porous region 53, and the width (length of one side) of the square is the same length as the width of the convex part 136. A plurality of convex portions 137 are provided. The plurality of convex portions 137 are arranged in a lattice shape, and each column constituting the lattice is provided so as to be arranged on an extension line of each convex portion 136.

  Even in such a case, since the cross-sectional area of the oxidizing gas channel 40 in the single cell can be made larger in the porous region 53 than in the dense region, the flow rate of the oxidizing gas in the porous region 53 is made slower. In addition, the same effect as in the first embodiment can be obtained.

C. Third embodiment:
FIG. 9 is a plan view showing the configuration of the separator 220 provided in the fuel cell of the third embodiment. Since the fuel cell of the third embodiment has a configuration similar to that of the fuel cells of the first and second embodiments, common portions are denoted by the same reference numerals, description thereof is omitted, and only different configurations are described. . The separator 220 is used in place of the separator 20 of the first embodiment, and an oxidizing gas flow path forming unit 230 for forming an oxidizing gas flow path in the single cell is provided between the separator 220 and the MEA 12. The oxidizing gas flow path forming part 230 has a plurality of convex parts 136 similar to those in the second embodiment in the dense region. Further, in the porous region 53, the oxidant gas flow path forming unit 230 forms a plurality of convex portions 237 in a direction in which convex portions having the same shape as the convex portions 137 of the second embodiment are rotated by approximately 90 degrees. It has a shape that is regularly provided at a position that hinders the flow of oxidizing gas (indicated by an arrow in FIG. 9) flowing from the flow path formed by the portion 136. By disposing the plurality of convex portions 237 in this way, the cross-sectional area of the oxidizing gas flow channel 40 in the single cell is made larger in the porous region 53 than in the dense region.

  Even in such a configuration, the flow area of the oxidizing gas channel in the single cell is made larger in the porous region 53 than in the dense region, so that the flow rate of the oxidizing gas in the porous region 53 is further reduced. The same effect as in the first embodiment can be obtained. Furthermore, in the fuel cell of the third embodiment, since the flow of the oxidizing gas flowing from the dense region is blocked by the convex portion 237 formed by the porous body, the moisture (particularly liquid water) carried by the oxidizing gas is made porous. It can be captured by the convex portion 237 formed by the body. Therefore, it is possible to enhance the effect of suppressing the movement of moisture in the gas flow direction due to the flow of the oxidizing gas within the single cell oxidizing gas flow path. Further, according to the fuel cell of the third embodiment, the flow of the oxidizing gas flowing from the dense region is blocked by the convex portion 237, so that the flow of the oxidizing gas flowing through the oxidizing gas flow path in the single cell can be stirred. The supply of oxygen to the cathode is promoted, and the gas utilization rate during power generation can be improved.

D. Fourth embodiment:
FIG. 10 is a plan view showing the configuration of a separator 320 provided in the fuel cell of the fourth embodiment. FIG. 11 is a cross-sectional view schematically showing the internal configuration of a single cell including the separator 320. Since the fuel cell of the fourth embodiment has a configuration similar to that of the fuel cells of the first and second embodiments, common portions are denoted by the same reference numerals, description thereof is omitted, and only different configurations are described. . The separator 320 is used in place of the separator 20 of the first embodiment, and is provided with an oxidizing gas flow path forming unit 330 for forming an in-single cell oxidizing gas flow path with the MEA 12. The oxidizing gas flow path forming part 330 has a plurality of convex parts 136 similar to those in the second embodiment in the dense region. Further, the oxidizing gas flow path forming part 330 does not have a concave structure for forming a flow path in the porous region 53, and a porous flow path part 337 made of a porous body having no uneven shape. I have. The porous body constituting the porous channel portion 337 has a substantial channel cross-sectional area larger than the channel cross-sectional area of the oxidizing gas channel in the single cell formed in the dense region (per unit cross-sectional area). The porosity and the pore diameter are sufficiently large. Further, the separator 320 includes a porous portion 52 similar to that in the first embodiment on the inter-cell cooling gas flow path side in the porous region 53. In the separator 320 of this example, the porous body constituting the porous flow path portion 337 has a larger porosity and pore diameter than the porous body constituting the porous portion 52.

  Also in the fuel cell of the fourth embodiment, the flow rate of the oxidizing gas in the porous region 53 is further increased by making the cross-sectional area of the oxidizing gas flow channel in the single cell larger than the entire dense region in the porous region 53. The effect similar to that of the first embodiment can be obtained by slowing down. Furthermore, in the fuel cell of the fourth embodiment, since the flow of the oxidizing gas flowing from the dense region is blocked by the porous flow path portion 337 formed by the porous body, the moisture (particularly liquid water) carried by the oxidizing gas is It can be captured by the porous channel portion 337. Therefore, the effect of suppressing the movement of moisture in the gas flow direction due to the flow of the oxidizing gas in the oxidizing gas flow path in the single cell can be enhanced. Further, according to the fuel cell of the fourth embodiment, the flow of the oxidizing gas flowing in the predetermined direction from the dense region is blocked by the porous flow path portion 337, so that the flow of the oxidizing gas flowing through the single cell oxidizing gas flow path. Since the supply of oxygen to the cathode is promoted, the gas utilization rate during power generation can be improved.

  The shape of the oxidizing gas flow path in the single cell formed in the dense region may be a shape other than a plurality of substantially parallel groove-shaped flow path groups. Further, in the separator 320, the porous channel portion 337 and the porous portion 52 that form the oxidizing gas flow channel in the single cell are made different in porosity and pore diameter. 337 and the porous portion 52 may be formed. At least on the side where the oxidizing gas flow path in the single cell is formed, the porosity and / or the pore diameter is such that the flow sectional area of the oxidizing gas flow path in the single cell is larger in the porous region 53 than in the dense region. The flow path part 337 should just have. However, the porosity and / or the pore diameter of the porous portion 52 that separates the intra-single cell oxidizing gas flow channel 40 and the inter-cell cooling gas flow channel are sufficiently reduced so that the inter-single cell oxidizing gas flow channel 40 and the inter-cell It is desirable to suppress a decrease in the oxidizing gas utilization rate due to the oxidizing gas moving to the cooling gas flow path.

E. Example 5:
12 and 13 are cross-sectional views schematically showing the internal structure of a single cell included in the fuel cell of the fifth embodiment. Since the fuel cell of the fifth embodiment has a configuration similar to that of the fuel cell of the first embodiment, common portions are denoted by the same reference numerals, description thereof is omitted, and only different configurations are described. The fuel cell according to the fifth embodiment includes a separator 420 instead of the separator 20. The separator 420 includes a porous portion 452 instead of the porous portion 52 in the separator 20. Further, like the separator 20, the separator 420 includes a plurality of convex portions 36 as a concavo-convex shape that forms a plurality of groove-like channel groups having the same width and substantially parallel. 12 shows a state in the cross section corresponding to FIG. 5, and FIG. 13 shows a state in the cross section corresponding to FIG. That is, FIG. 12 shows a cross section that is parallel to the convex portion 36 and does not include the convex portion 36 and that passes through the cooling gas upstream region 50. FIG. 13 shows a cross section that is parallel to the convex portion 36 and does not include the convex portion 36 and that passes through the cooling gas downstream region 54 (see FIGS. 3A and 4).

  In the fuel cell of the present embodiment, as in the first embodiment, the depth of the oxidizing gas flow path 40 in the single cell is formed deeper in the porous region 53 than in the dense region. That is, when the depth of the oxidizing gas channel 40 in the single cell in the dense region is “a” and the depth of the oxidizing gas channel 40 in the single cell in the porous region 53 is “d”, a <d It holds. Thereby, the flow rate of the oxidizing gas is slower in the porous region 53 than in the dense region. Therefore, as in the first embodiment, in the porous region 53, the moisture movement in the gas flow direction due to the flow of the oxidizing gas is suppressed, and the cooling gas is supplied from the oxidizing gas flow path 40 in the single cell via the porous portion 52. It is possible to improve the moisture transfer efficiency to the flow path side. In the fifth embodiment, the depth of the oxidizing gas flow path 40 in the single cell is made uniform in the porous region 53, but the cooling gas upstream region 50 and the cooling gas downstream region 54 are the same as in the first embodiment. And may be different.

  Furthermore, in the fuel cell of the present embodiment, the cooling gas flow path between cells is formed shallower in the cooling gas downstream region 54 than in the cooling gas upstream region 50. That is, when the groove depth forming the inter-cell cooling gas flow path in the cooling gas upstream region 50 is “e” and the groove depth forming the inter-cell cooling gas flow path in the cooling gas downstream region 54 is “f”, e> f holds. Here, since the cooling gas flow path forming portion formed in the porous portion 452 has an uneven shape including a plurality of parallel grooves having the same width as in the first embodiment, a shallow flow path is formed. As the region is larger, the flow path cross-sectional area is smaller (the gas flow rate per unit flow path cross-sectional area is larger). As described above, the cooling gas downstream region 54 has a smaller cross-sectional area of the inter-cell cooling gas flow channel than the cooling gas upstream region 50, so that the cooling gas downstream region 54 has a higher flow velocity of the cooling gas. . Therefore, in the inter-cell cooling gas flow path in the cooling gas downstream region 54, the boundary layer is made thinner by increasing the flow speed of the cooling gas, and the moisture is evaporated from the porous portion 452 to the inter-cell cooling gas flow path. Can be promoted. As described above, the cooling gas has higher humidity on the downstream side, and the cooling gas downstream region 54 is less efficient in vaporizing water from the porous portion 452 into the cooling gas than the cooling gas upstream region 50. In this embodiment, by promoting the vaporization of water from the porous portion 452 into the cooling gas in the cooling gas downstream region 54, the vaporization efficiency of the water from the porous portion 452 into the cooling gas is increased. Can be secured. In this way, the inter-cell cooling gas flow path functions as a flow path area restricting section that narrows the flow cross-sectional area in the cooling gas flow direction of the cooling gas flow path on the downstream side rather than the upstream side, so On the side, it functions as a cooling gas flow rate adjusting unit that increases the flow rate of the cooling gas. Thereby, the inter-cell cooling gas flow path functions as a water movement promoting part that promotes the movement of water from the intra-single cell oxidizing gas flow path 40 to the inter-cell cooling gas flow path on the downstream side of the upstream side.

  In the present embodiment, the flow velocity of the cooling gas is made different between the cooling gas upstream region 50 and the cooling gas downstream region 54 by the uneven shape provided on the surface of the porous portion 452, but different configurations may be adopted. For example, in the separator 22 that forms the inter-cell cooling gas flow path adjacent to the separator 420 and adjacent to the separator 420, the uneven shape for forming the inter-cell cooling gas flow path is changed to the cooling gas upstream region 50 and the cooling gas. It is also possible to change the flow velocity by making it different from the downstream region 54.

F. Example 6:
This is different from the fifth embodiment in order to promote the movement of moisture from the intra-single-cell oxidizing gas flow channel 40 to the inter-cell cooling gas flow channel in a region downstream from the upstream side of the inter-cell cooling gas flow channel. It is also possible to provide a moisture transfer promoting part having the configuration. As a sixth example which is an example, a separator having a porous portion in which the cooling gas downstream region 54 has a larger porosity and / or pore diameter than the cooling gas upstream region 50 is used. It can replace with the separator 20 and can be used. Thereby, in the cooling gas downstream region 54, the water movement from the intra-single cell oxidizing gas flow channel 40 to the inter-cell cooling gas flow channel via the porous portion is promoted more than in the cooling gas upstream region 50, and the fifth embodiment The same effect as the example can be obtained.

G. Seventh embodiment:
In order to promote the movement of moisture from the oxidant gas flow path 40 in the single cell to the inter-cell cooling gas flow path on the downstream side of the upstream side, a configuration in which a different moisture movement promoting portion is provided as a seventh embodiment. This will be described below. In the fuel cell of the seventh embodiment, the porous portion provided in the separator used in place of the separator 20 of the first embodiment is such that the cooling gas downstream region 54 has a lower inter-cell cooling gas flow than the cooling gas upstream region 50. The surface area on the side forming the path is formed large. Thus, in the cooling gas downstream region 54, the vaporization of moisture from the porous portion to the inter-cell cooling gas flow channel is promoted more than in the cooling gas upstream region 50, and the same effect as in the fifth embodiment can be obtained. . Here, in the porous part provided in the separator, in order to adjust the surface area on the side where the inter-cell cooling gas flow path is formed, for example, when the porous part is press-molded, an uneven shape is formed on the mold used for the press. By forming, the surface can be processed into a concavo-convex shape having a desired surface area simultaneously with pressing. Alternatively, after forming the porous portion, it may be processed into a concavo-convex shape having a desired surface area by machining.

  In the porous portion constituting the porous region of the separator, a plurality of combinations of the water movement promoting portions shown in the fifth to seventh embodiments are provided in combination, and the porous portion is provided in the cooling gas downstream region 54. Moisture movement to the inter-cell cooling gas flow path may be further promoted.

E. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

E1. Modification 1 (Modification regarding arrangement of porous body):
In the first to seventh embodiments, the porous region 53 including the porous portion is provided in the downstream region of the oxidizing gas flow channel 40 in the single cell, but may be another region. In order to gradually increase the content of generated water while the oxidizing gas passes through the single-cell oxidizing gas flow path 40, a porous region is provided downstream of the oxidizing gas having a high water content so that the oxidizing gas flow in the single-cell Moisture movement from the passage 40 to the inter-cell cooling gas passage through the porous portion can be effectively performed. However, a porous region may be provided in another region, and by applying the present invention, the single-cell in-cell oxidizing gas channel 40 is passed through the porous body from the intra-cell cooling gas channel in the porous region. The efficiency of moving moisture can be improved.

  In the fuel cells of the first to seventh embodiments, the dense region is constituted by the gas-impermeable separator base, but on the separator base constituting the dense region, the oxidizing gas flow path 40 in the single cell is formed. A porous body may be provided on the surface. If a porous body is disposed on the surface forming the oxidizing gas flow path 40 in the single cell, the water in the oxidizing gas flow path 40 in the single cell is easily taken into the porous body disposed on the surface and flows. It spreads in the oxidizing gas flow path 40 in the single cell without staying at a specific place in the path. Therefore, it is possible to prevent the generated water from blocking the oxidizing gas channel 40 in the single cell. Even if the separator base is provided with a porous body on the surface forming the single-cell oxidizing gas flow channel 40, the single-cell oxidizing gas flow channel 40 and the inter-cell cooling gas flow channel are porous only in the porous region. It suffices to be informed via a physical body. In the porous region in the oxidizing gas flow path 40 in the single cell, if a moisture discharge suppression unit that suppresses the movement of moisture in the gas flow direction due to the flow of the oxidizing gas as compared with the dense region is provided, the same as in the embodiment. The effect is obtained.

In the first to seventh embodiments, the entire porous region is formed of a porous body, but a different configuration may be used. For example, the plurality of protrusions 36 (see FIG. 4) for forming the single-cell oxidant gas flow path 40 are densely formed, and the single-cell oxidant gas flow path 40 and the inter-cell cooling gas flow path are formed. It is good also as forming only a part to separate with a porous body. In the porous region 53, it is desirable that the convex portion 36 is also formed of a porous body, so that the efficiency of retaining moisture in the single-cell oxidizing gas flow path 40 can be improved, but as described above, the porous region 53 It is also possible to form a part of the substrate with a high density.

E2. Modification 2 (Modification regarding cooling gas):
In the first to seventh embodiments, the cooling gas that has passed through the inter-cell cooling gas channel is supplied as the oxidizing gas to the intra-cell oxidizing gas channel 40, but the inter-cell cooling gas channel and the intra-cell oxidizing gas are supplied. Air may be independently supplied to the gas flow path. Alternatively, instead of using a gas of the same type as an oxidizing gas (reactive gas used for electrochemical reaction) as a moisture source for moving moisture to the inter-cell cooling gas flow path side through the porous portion, a different gas is used. May be used as a cooling gas. In this case, it is desirable to select a gas that does not affect the electrochemical reaction even if mixed in the reaction gas as the cooling gas. Further, if the cooling gas pressure is made lower than the reaction gas pressure, it is possible to effectively prevent the cooling gas from being mixed into the reaction gas.

  In the first to seventh embodiments, the cooling gas is supplied to the porous region and the cooling liquid is supplied to the dense region to cool the fuel cell. However, the cooling gas flows to the porous region and the reaction is performed. A different configuration may be used as long as moisture can move from the gas flow path to the cooling gas flow path via the porous portion. In the configuration of the example, the cooling efficiency is improved by cooling the dense region, which is the upstream region where the oxygen concentration in the oxidizing gas is high and the electrochemical reaction proceeds more actively, using a liquid. As an alternative, only the cooling gas may be used.

E3. Modification 3 (Modification regarding the gas flow path to which the invention is applied):
In the first to seventh embodiments, the porous portion is disposed in the gas separator disposed between the single-cell oxidizing gas flow path 40 and the inter-cell cooling gas flow path. A similar porous portion may be disposed in the gas separator disposed between the gas flow path 42 and the inter-cell cooling gas flow path. When the present invention is applied to the flow path of the fuel gas that is a reaction gas used in the electrochemical reaction, the fuel gas flow in the single cell is discharged when the water in the fuel gas flow path in the single cell is discharged to the cooling gas flow path side. The efficiency of moving the moisture in the channel to the cooling gas channel side through the porous part can be improved. In this case, as the cooling gas, it is desirable to use the fuel gas before being supplied to the fuel gas passage in the single cell. That is, it is desirable to use the same kind of gas as the reaction gas to be drained as the cooling gas.

  Or it is good also as providing the porous part similar to the porous part of an Example in both the separator 20 and the separator 22. FIG. With such a configuration, the same effect of improving the efficiency of transferring moisture to the cooling gas via the porous portion in both the single-cell oxidizing gas flow channel 40 and the single-cell fuel gas flow channel 42 can be obtained. Obtainable. At this time, if the cooling gas pressure is sufficiently lower than the fuel gas pressure and the oxidizing gas pressure, it is possible to prevent the fuel gas and the oxidizing gas from being mixed.

E4. Modification 4:
In the first to seventh embodiments, the connection flow path 82 that connects the inter-cell cooling gas flow path and the single-cell oxidizing gas flow path 40 is provided. One end of the stacking direction can be formed by connecting the cooling gas discharge manifold end and the oxidizing gas supply manifold end. Alternatively, the connection flow path 82 can be provided in each cell plane in the stack constituting the fuel cell.

E5. Modification 5:
In the first to seventh embodiments, the fuel cell is a polymer electrolyte fuel cell, but it can also be applied to different types of fuel cells. The present invention is a fuel cell configured by stacking members including a separator, the amount of water in the reaction gas channel being increased during power generation, and a fuel cell that uses a cooling gas to cool the fuel cell. The same effect can be obtained by applying. In particular, when applying a configuration in which a cooling gas containing moisture supplied through the porous portion is used as a reaction gas to a fuel cell including an electrolyte layer used in a wet state, the moisture shortage of the electrolyte layer is prevented. An effect is obtained.

It is explanatory drawing which shows schematic structure of the fuel cell in 1st Example. 2 is an exploded perspective view showing a configuration of a single cell 10. FIG. 3 is a plan view showing a state of a separator 20. FIG. It is a top view showing the separator 20 which forms the substantially parallel groove-shaped flow path group. 2 is a cross-sectional view schematically showing an internal configuration of a single cell 10. FIG. 2 is a cross-sectional view schematically showing an internal configuration of a single cell 10. FIG. 2 is a cross-sectional view schematically showing an internal configuration of a single cell 10. FIG. 3 is a plan view illustrating a configuration of a separator 120. FIG. 3 is a plan view illustrating a configuration of a separator 220. FIG. 3 is a plan view illustrating a configuration of a separator 320. FIG. It is sectional drawing which represents typically the internal structure of the single cell of 4th Example. It is sectional drawing which represents typically the internal structure of the single cell of 5th Example. It is sectional drawing which represents typically the internal structure of the single cell of 5th Example.

Explanation of symbols

10 ... Single cell 12 ... MEA
13, 14 ... Gas diffusion layer 20, 22, 120, 220, 320, 420 ... Separator 22a, 22b ... Hole 24a, 24b ... Hole 26a, 26b ... Hole 28a, 28b ... Hole 30, 130, 230, 330 ... Oxidizing gas flow path forming part 32, 33 ... Coolant liquid flow path forming part 34, 35 ... Cooling gas flow path forming part 36 ... Convex part 38 ... Sealing member 40 ... In-single cell oxidizing gas flow path 42 ... Inside single cell Fuel gas flow path 44 ... Oxidizing gas supply manifold 46 ... Oxidizing gas discharge manifold 50 ... Cooling gas upstream region 52, 452 ... Porous portion 53 ... Porous region 54 ... Cooling gas downstream region 60 ... Fuel cell stack 61 ... Coolant circulation Unit 62 ... Fuel gas supply unit 63 ... Flow rate adjustment valve 64 ... Blower 65 ... Circulation pump 66 ... Heat exchanger 68 ... Control unit 70 ... Fuel gas flow path 72 ... Oxidation gas flow path 74 ... Cooling gas flow path 76 ... Cooling liquid flow path 80 ... Air flow path 82 ... Connection flow path 84 ... Branch flow path 136, 137, 237 ... Projection 337 ... Porous flow path section

Claims (14)

A fuel cell,
An electrolyte layer;
Adjacent the electrode between the electrolyte layer,
Having a first surface that forms a reaction gas flow path through which a reaction gas used in an electrochemical reaction flows, and a second surface that forms a cooling gas flow path through which a cooling gas flows;
A dense region comprising a base material composed of a gas-impermeable dense member, and a porous region provided so as to communicate between the reaction gas flow channel and the cooling gas flow channel,
In the first surface, as the reaction gas flow path, a gas separator that forms a flow path in which a flow path formed in the dense area and a flow path formed in the porous area are continuously formed;
In addition,
The reaction gas flow path formed in the porous region suppresses the movement of moisture in the flow direction of the reaction gas due to the flow of the reaction gas, compared to the reaction gas flow channel formed in the dense region. As a moisture discharge suppression unit, the flow rate of the reaction gas in the reaction gas channel formed in the porous region is reduced as compared with the flow rate of the reaction gas in the reaction gas channel formed in the dense region. A fuel cell including a flow velocity reduction unit. The fuel cell according to claim 1, wherein
The flow velocity reduction portion is the reaction gas channel in the porous region in which a channel cross section is formed larger than a channel cross section of the reaction gas channel formed in the dense region. The fuel cell according to claim 2, wherein
The gas separator has a recess for forming the gas flow path over the dense region and the porous region on the first surface,
The flow velocity reduction portion is the reaction gas flow path formed by the recess provided in the porous region that is formed deeper than the recess provided in the dense region. A fuel cell,
An electrolyte layer;
Adjacent the electrode between the electrolyte layer,
Having a first surface that forms a reaction gas flow path through which a reaction gas used in an electrochemical reaction flows, and a second surface that forms a cooling gas flow path through which a cooling gas flows;
A dense region comprising a base material composed of a gas-impermeable dense member, and a porous region provided so as to communicate between the reaction gas channel and the cooling gas channel;
In the first surface, as the reaction gas flow path, a gas separator that forms a flow path in which a flow path formed in the dense area and a flow path formed in the porous area are continuously formed;
In addition,
The reaction gas flow path formed in the porous region suppresses the movement of moisture in the flow direction of the reaction gas due to the flow of the reaction gas, compared to the reaction gas flow channel formed in the dense region. A fuel cell comprising a gas flow obstructing unit that prevents a flow of the reaction gas toward a predetermined direction in the reaction gas flow path formed in the porous region as a moisture discharge suppressing unit. The fuel cell according to claim 4, wherein
The gas separator has a concave portion for forming the reaction gas flow channel in the dense region on the first surface, and the reaction gas flow channel is formed in the porous region to form an interior. A porous portion through which the reaction gas passes;
The gas flow obstructing part is the porous part provided continuously in the concave part. A fuel cell according to any one of claims 1 to 5,
A fuel cell further comprising: a connection channel that connects the cooling gas channel and the reaction gas channel and guides the cooling gas that has passed through the cooling gas channel to the reaction gas channel as the reaction gas. The fuel cell according to any one of claims 1 to 6,
The reaction gas is an oxidizing gas containing oxygen. The fuel cell according to any one of claims 1 to 7,
The porous region forms the reaction gas channel on the downstream side as compared with the reaction gas channel formed in the dense region. The fuel cell according to any one of claims 1 to 8, further comprising:
In the porous region, the region corresponding to the downstream side of the cooling gas channel corresponds to the upstream side of the cooling gas channel as a moisture retention preventing part for preventing the retention of moisture in the reaction gas channel. A fuel cell comprising the reactive gas flow channel having a flow channel cross-sectional area smaller than the reactive gas flow channel formed in a region. The fuel cell according to any one of claims 1 to 9 ,
The cooling gas flow path is formed in the porous region on the second surface of the gas separator,
The fuel cell further includes:
The cooling gas as a moisture movement promoting part that promotes the movement of moisture from the reaction gas channel to the cooling gas channel via the porous region on the downstream side compared to the upstream side of the cooling gas channel. A fuel cell comprising a cooling gas flow rate adjustment unit that increases a flow rate of cooling gas on the downstream side of the upstream side of the flow path. The fuel cell according to claim 10, wherein
The cooling gas flow rate adjustment unit is a channel area throttle unit that throttles a channel cross-sectional area in the cooling gas flow direction of the cooling gas channel on the downstream side of the upstream side of the cooling gas channel. The fuel cell according to any one of claims 1 to 9 ,
The cooling gas flow path is formed in the porous region on the second surface of the gas separator,
The fuel cell is,
Downstream than on the upstream side of the pre-Symbol cooling gas flow path, as a moisture transfer-promoting portion that promotes the movement of moisture into the cooling gas flow path from said porous the reactant gas flow path through the area, the cooling A fuel cell comprising the porous region in which a region forming a downstream side of a gas flow path has a larger pore diameter and / or porosity than a region forming an upstream side. The fuel cell according to any one of claims 1 to 9 ,
The cooling gas flow path is formed in the porous region on the second surface of the gas separator,
The fuel cell further includes:
The gas separator as a moisture movement promoting part that promotes the movement of moisture from the reaction gas channel to the cooling gas channel via the porous region on the downstream side compared to the upstream side of the cooling gas channel. And a cooling gas flow path forming portion for forming the cooling gas flow path having a flow path surface area on the downstream side larger than that on the upstream side. battery. A gas separator for a fuel cell that has a first surface and a second surface and is laminated together with a member that forms an electrolyte layer and an electrode to form a fuel cell,
A dense portion including a base material composed of a gas impermeable dense member;
A porous portion arranged to allow movement of moisture between the first surface and the second surface;
A fluid channel is formed between the electrode on the first surface over the dense part and the porous part, and a channel cross-sectional area of the fluid channel formed in the porous part is And a flow path forming part having a shape that is larger than the flow path cross-sectional area of the fluid flow path formed in the dense part.

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