JP2005032578A - Separator for fuel cell, fuel cell, and fuel cell vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the degradation of generating characteristics due to increase in contacting resistance and variations in gas flow, by preventing the warping of separators forming a metal thin plate in corrugated form. <P>SOLUTION: The fuel cell separators, which are arranged opposed to each other on each electrode face on both sides of a solid electrolyte and has gas passages 11, 17 by which an oxidant gas or a fuel gas is supplied on the side opposed to the electrode face and cooling water passages 18 on the opposite side face to the electrode face, comprises respectively the gas passages 11, 17 and cooling water passages 18 by forming the plate material in corrugated form and with concave and convex shapes. The sum of the passage width dimension or sum of passage cross section of these gas passages 11, 17 is made equal to the sum of the passage width dimension or passage cross section of the cooling water passages 18 formed on the opposite side face of these. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a separator for a fuel cell, a fuel cell, and a fuel cell vehicle used for a solid oxide fuel cell.

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

  For this reason, from the viewpoint of protecting the global environment, it has been studied to use a fuel cell as a power source of a motor that operates in place of an internal combustion engine of an automobile, and to drive the automobile by this motor.

  Various types of fuel cells such as solid polymer type, phosphoric acid type, molten carbonate type and solid oxide type are known depending on the type of electrolyte provided with electrodes (fuel electrode, oxidant electrode) on both sides. . Among these, the electrode reaction in a polymer electrolyte fuel cell (PEFC) is as follows.

Fuel electrode: H ₂ → 2H ⁺ + 2e ⁻ (1)
Oxidant electrode: (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
Fuel gas is supplied to the fuel electrode, and the reaction of the above formula (1) proceeds to generate protons. In the hydrated state, protons move through the electrolyte, here the solid polymer electrolyte, and reach the oxidant electrode. At the oxidant electrode, the reaction of the above formula (2) proceeds by the proton and oxygen in the supplied oxidant gas. As the reactions of the equations (1) and (2) proceed at each pole, the fuel cell generates an electromotive force.

  As described above, the solid polymer electrolyte fuel cell is a fuel cell that utilizes a function as a proton conductive electrolyte when a polymer resin film having a proton exchange group in a molecule is saturatedly hydrated. Since this can operate at a relatively low temperature and perform efficient power generation, various uses are expected including those for electric vehicles.

In such a polymer electrolyte fuel cell, in order to obtain a high output with a small volume and to obtain a highly efficient fuel cell system, as described in Patent Document 1 below, The gas flow path provided in the opposing separator is separated into a supply gas flow path for supplying the reaction gas to the electrode catalyst layer and a discharge gas flow path for recovering the gas from the catalyst layer. ing.
JP, 11-16591, A Here, at the same time as increasing the reaction area by arranging supply gas passages and discharge gas passages alternately and actively supplying gas to the supply gas passages. The discharge of generated water is improved. As a result, all the gas in the supply gas flow path is discharged to the discharge gas flow path through the gas diffusion electrode and the catalyst layer. For this reason, the catalyst electrode can be used efficiently, and the output per unit volume can be improved while maintaining high efficiency.

  In addition, a solid polymer electrolyte fuel cell has a gas diffusion electrode (consisting of a gas diffusion layer and a catalyst layer, and the surface on which the catalyst exists is in contact with the polymer electrolyte membrane) on both sides of the solid polymer electrolyte membrane. It has a structure in which a membrane electrode assembly (MEA) bonded by means and a carbon or metal gas separator are laminated.

  As a gas separator, a carbon material is very often used, but since it is formed by cutting, the cost is high and the strength is low, so it is necessary to increase the thickness of the separator, which increases the volume of the fuel cell. There is a problem.

Therefore, in a conventional solid polymer electrolyte fuel cell as shown in Patent Document 2 below, a reaction gas flow path is formed between the separator and the MEA, and cooling is performed between the separator plate and the intermediate plate. A water channel is provided.
JP, 2000-228207, A Here, an intermediate board is a partition arranged between a separator provided with a reaction gas channel and a cooling water channel, and a separator provided with a reaction gas channel, and by this composition In this case, a member for forming the cooling water flow path is not required, and the fuel cell is aimed to be reduced in size and weight. However, the presence of the partition wall itself increases the size and weight of the fuel cell.

  Further, since the separator material electrically connects the MEAs, high electrical conductivity and low contact resistance with the constituent materials are required. Therefore, “Development and Practical Use of Polymer Electrolyte Fuel Cell”, p. As disclosed in FIG. 92 (FIG. 8), as the separator, a carbon material formed into a plate shape and a reaction gas flow path surface formed on both sides thereof is used.

  However, although carbon materials are superior in that they have low contact resistance with constituent materials, they are less strong than metal materials, so when a fuel cell is mounted on an automobile or the like, it is required to be made thinner and smaller. However, the thickness is naturally limited, and a thickness of about 1 to 5 mm is common.

In order to reduce the size and cost of the fuel cell as described above, as disclosed in Patent Documents 3 and 4 below, a metal thin plate is used as a separator material, and it is formed into a waveform by processing such as press molding. Thus, attempts have been made to reduce the thickness of the separator.
JP 2000-323149 A JP 2002-190305 A

  In such a solid polymer electrolyte fuel cell, in order to improve the output density, as shown in Patent Document 1 described above, the gas flow path provided in the separator is divided into a supply gas flow path and a discharge gas flow. Use a flow path pattern (also called an interdigitate type) that separates the gas flow paths and alternately supplies these gas flow paths and actively supplies gas to the supply gas flow paths. Is valid.

  However, in such a configuration, the separator is warped due to the difference in the concave and convex shapes of the separator material in the cross-sectional shape orthogonal to the flow path. For this reason, the deterioration of assemblability occurs, and the contact resistance between the electrode after assembly and the rib surface of the separator (the corrugated convex portion on the surface) is uneven, which increases the total contact resistance, Deterioration of power generation characteristics due to variations becomes a problem.

  In view of this, an object of the present invention is to prevent a separator having a corrugated metal thin plate from being warped, thereby preventing a decrease in power generation characteristics due to an increase in contact resistance and a variation in gas distribution.

  In order to achieve the above object, the present invention is provided with a gas flow path that is disposed to face each electrode surface on both sides of a solid electrolyte and that is supplied with an oxidant gas or a fuel gas on the surface facing this electrode surface. In addition, in the fuel cell separator provided with a cooling water channel on the side opposite to the electrode surface, a plate material is formed in a corrugated shape, and the gas channel and the cooling water channel are respectively formed on both surfaces thereof. In addition, the respective areas of the cooling water channel in plan view as viewed from the direction facing the surface of the separator are set to be equal to each other.

  According to the present invention, the gas flow path and the cooling water flow path are respectively formed on both surfaces of the corrugated plate material, and the gas flow path and the cooling water flow path are viewed in a plan view from the direction facing the separator surface. Since the respective areas are equal to each other, the tension on both surfaces of the separator in which the gas flow path and the cooling water flow path are formed with unevenness can be equalized, and the warpage of the separator can be reduced. As a result, assemblability of the fuel cell is improved, non-uniform surface pressure between the electrode and the separator in the assembled fuel cell can be prevented, the total contact resistance can be reduced, and the variation in gas distribution can be reduced, improving the power generation characteristics. It becomes possible to do.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1-8 is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells (henceforth only called a separator) by 1st Embodiment-8th Embodiment of this invention. 9 to 11 are schematic views showing the cross-sectional shapes of the separators of Comparative Examples 1 to 3. The separator described below is a separator on the fuel electrode side formed with the gas flow path facing the fuel electrode, but the oxidant electrode formed with the gas flow path facing the oxidant electrode. It may be a separator on the side.

  The separator 1 according to each of the embodiments and the comparative examples described above has a gas flow path shape as shown in a perspective view of FIG. 12 on one surface (surface on the front side in FIG. 12). In this gas flow path shape, a supply gas flow path 3 for supplying fuel gas to the electrode and a discharge gas flow path 5 for discharging the fuel gas from the electrode are provided independently of each other.

  The supply gas flow path 3 includes a fuel gas supply main flow path 9 communicating with the fuel gas supply hole 7 as a supply port, and a fuel gas supply branch flow path 11 branched from the fuel supply main flow path 9. On the other hand, the discharge gas flow path 5 has a fuel gas discharge main flow path 15 communicating with the fuel gas discharge hole 13 as a discharge port, and a fuel gas discharge branch flow path 17 branched from the fuel gas discharge main flow path 15. A plurality of fuel gas supply branch passages 11 and fuel gas discharge branch passages 17 are alternately arranged.

  Further, a cooling water flow path (indicated by reference numeral 18 in FIGS. 1 to 11) is formed on the other surface of the separator 1 (the surface on the back side in FIG. 12). 8 corresponds to a part of the AA cross section of FIG.

  Further, the separator 1 is provided with an oxidant gas supply hole 19, a discharge hole 21, a cooling water supply hole 23, and a discharge hole 25, respectively.

  Such a separator 1 is formed by press-molding a SUS16L plate having a thickness of 0.1 mm into a predetermined corrugated shape as shown in FIG. In all of the present embodiments and comparative examples, the depth of the gas flow path and the cooling water flow path is 0.5 mm.

  FIG. 13 is an exploded perspective view of a fuel cell stack 45 configured by stacking a plurality of single cells of a fuel cell using the separator 1 described above. In this fuel cell stack 45, a separator 1 on the fuel electrode side and a separator 1 on the oxidizer electrode side are arranged on both sides of the MEA 27 to form a single cell, and a large number of single cells are stacked and end plates 29 are arranged on both ends thereof. These are fastened with fastening bolts 31. As described in the prior art, the MEA 27 is a membrane electrode assembly in which a gas diffusion electrode composed of a gas diffusion layer and a catalyst layer is bonded to both surfaces of a solid polymer electrolyte membrane by means such as hot pressing. .

  For this fuel cell stack 45, a fuel supply port 33, a discharge port 35, an oxidant supply port 37, a discharge port 39, a cooling water supply port 41, and a discharge port 43 are formed in one end plate 29, respectively. . Each of these supply ports and discharge ports penetrates the entire fuel cell stack 45 in the stacking direction. The fuel gas supply hole 7 shown in FIG. 12 corresponds to the fuel supply port 33, the fuel gas discharge hole 13 corresponds to the fuel discharge port 35, and the oxidant gas supply hole 19 corresponds to the oxidant supply port 37. The oxidant gas discharge hole 21 corresponds to the oxidant discharge port 39, the cooling water supply hole 23 corresponds to the cooling water supply port 41, and the cooling water discharge hole 25 corresponds to the cooling water discharge port 43, respectively. Yes.

  Next, each embodiment of FIGS. 1-8 is demonstrated.

  In the first embodiment shown in FIG. 1, the flow path width B1 of the fuel gas supply branch flow path 11 is increased to 2 mm, and the flow path width B2 of the fuel gas discharge branch flow path 17 is decreased to 1 mm. Then, the fuel gas supply branch flow channel 11 having the flow channel width B1 is made equal to the width dimension L1 of the cooling water flow channel 18 adjacent to the fuel gas supply branch flow channel 11 on the opposite side to the fuel gas supply branch flow channel B1. The width L2 of the cooling water flow path 18 adjacent to the path 17 on the opposite side is equal to B2. In other words, the cooling water passages 18 having narrow passages and wide passages are alternately arranged along the direction in which the cooling water passages 18 are arranged.

  Further, by forming the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17, the end surfaces 11 a and 17 a of the projecting portions projecting on the opposite side surface and the cooling water channel 18 are formed on the opposite side. Each of the end surfaces 18a of the convex portions protruding on the surface is flat.

  The cross-sectional shape perpendicular to the gas flow direction (direction perpendicular to the paper surface in FIG. 1) of the separator 1 shown in FIG. 1 is a gas flow path (fuel gas supply branch flow path 11 and fuel gas discharge branch flow path 17). It is point-symmetric with respect to a point P that is the center in the arrangement direction.

  Further, in the cross-sectional shape, the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 along the gas channel arrangement direction, and the cooling water channel The sum of the channel width dimensions or the sum of the channel cross-sectional areas of the cooling water channels 18 along the 18 arrangement directions is equal to each other.

  Thus, the fuel gas supply branch passage 11 and the fuel gas discharge branch passage formed on one surface of the separator 1 including the fuel gas supply main passage 9 and the fuel gas discharge main passage 15 shown in FIG. 17, that is, the total area in a plan view as viewed from the direction facing one surface of the separator 1 in the entire gas flow path, and the plane as viewed from the direction facing the other surface of the separator 1 in the entire cooling water flow path 18. The sum of the visual areas is equivalent to each other.

  In the second embodiment shown in FIG. 2, the supply gas flow path 3, the discharge gas flow path 5 and the cooling water flow path 18 have the same flow width and arrangement as in the first embodiment, and the fuel gas The end surfaces 11a and 17a of the projections projecting to the opposite side surface by the formation of the supply branch channel 11 and the fuel gas discharge branch channel 17 and the opposite side surface by the formation of the cooling water channel 18 are formed. Each of the end surfaces 18a of the convex portions is a convex curved surface.

  More specifically, the curvature radii RB1 and RL1 of the end surfaces 11a and 18a corresponding to the fuel gas supply branch channel 11 and the coolant channel 18 having the same channel widths B1 and L1 are 4.5 mm, which are equivalent to each other. The curvature radii RB2 and RL2 of the end surfaces 17a and 18a corresponding to the fuel gas discharge branch channel 17 and the coolant channel 18 having the channel widths B2 and L2 are 2 mm.

  The shape of the cross section perpendicular to the gas flow direction of the separator 1 according to the second embodiment is also point-symmetric with respect to the point P as in the first embodiment. Further, in this cross-sectional shape, the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 along the gas channel arrangement direction, and the cooling water channel 18 is equal to the sum of the channel width dimensions or channel cross-sectional areas of the cooling water channels 18 along the 18 arrangement direction.

  The third embodiment shown in FIG. 3 is different from the second embodiment shown in FIG. 2 in that each of the fuel gas discharge branch flow path 17 and the cooling water flow path 18 having flow path widths B2 and L2 that are equivalent to each other. The curvature radii RB2 and RL2 of the end faces 17a and 18a are 0.2 mm. Other configurations are the same as those of the second embodiment.

  Therefore, in the third embodiment, as in the first embodiment, the cross-sectional shape orthogonal to the gas flow direction of the separator 1 is symmetric with respect to the point P. In the cross-sectional shape, the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 along the gas channel arrangement direction, and the arrangement of the cooling water channel 18 This is equal to the sum of the channel width dimension or channel cross-sectional area of the coolant channel 18 along the direction.

  The fourth embodiment shown in FIG. 4 is that the flow width B1 of the fuel gas supply branch flow path 11 is increased to 2 mm and the flow path width B2 of the fuel gas discharge branch flow path 17 is reduced to 1 mm. This is the same as the first embodiment.

  On the other hand, the flow path width of the cooling water flow path 18 is opposite to the flow path width L1 of the cooling water flow path 18 adjacent to the fuel gas supply branch flow path 11 on the opposite side and the fuel gas discharge branch flow path 17. Both of the channel widths L2 of the cooling water channels 18 adjacent on the side surface are made equal to each other so that (B1 + B2) /2=1.5 mm.

  Further, by forming the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17, the end surfaces 11 a and 17 a of the projecting portions projecting on the opposite side surface and the cooling water channel 18 are formed on the opposite side. Each of the end surfaces 18a of the convex portions protruding on the surface is flat.

  Also in the fourth embodiment, the shape of the cross section orthogonal to the gas flow direction of the separator 1 shown in FIG. 4 (the direction orthogonal to the paper surface in FIG. 4) is the fuel gas supply branch along the gas flow path arrangement direction. The sum of the channel width dimensions or the sum of the channel cross-sectional areas of the channel 11 and the fuel gas discharge branch channel 17 and the sum or flow of the channel width dimensions of the cooling water channel 18 along the direction in which the cooling water channels 18 are arranged. The sum of the road cross-sectional areas is equal to each other.

  The fifth embodiment shown in FIG. 5 is different from the fourth embodiment shown in FIG. 4 in the width and arrangement of the supply gas passage 3, the discharge gas passage 5, and the cooling water passage 18. Similarly, the formation of the fuel gas supply branch passage 11 and the fuel gas discharge branch passage 17 is opposite to this by the formation of the end faces 11a and 17a of the convex portions protruding on the opposite surface and the cooling water passage 18. The end surface 18a of each convex portion protruding on the side surface is a convex curved surface.

  Specifically, the curvature radius RB1 of the end face 11a corresponding to the fuel gas supply branch flow path 11 is 4.5 mm, the curvature radius RB2 of the end face 17a corresponding to the fuel gas discharge branch flow path 17 is 2 mm, and the cooling water flow path 18 The curvature radii RL1 and RL2 corresponding to the end face 18a are 3 mm.

  Also in the fifth embodiment, the shape of the cross section perpendicular to the gas flow direction of the separator 1 is the flow path width of the fuel gas supply branch flow path 11 and the fuel gas discharge branch flow path 17 along the arrangement direction of the gas flow paths. The sum of dimensions or the sum of channel cross-sectional areas is equal to the sum of channel width dimensions or the sum of channel cross-sectional areas of the coolant channels 18 along the arrangement direction of the coolant channels 18.

  In the sixth embodiment shown in FIG. 6, the end surfaces 11 a and 17 a of the projecting portions projecting to the opposite surface by the formation of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 are flat. This is different from the fifth embodiment. Other configurations are the same as those of the fifth embodiment.

  In the seventh embodiment shown in FIG. 7, the fuel gas supply branch flow path 11, the fuel gas discharge branch flow path 17 and the cooling water flow path 18 are all equal to 1.5 mm in width.

  Further, by forming the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17, the end surfaces 11 a and 17 a of the projecting portions projecting on the opposite side surface and the cooling water channel 18 are formed on the opposite side. Each of the end surfaces 18a of the convex portions protruding on the surface is flat.

  The shape of the cross section perpendicular to the gas flow direction of the separator 1 according to the seventh embodiment is also point-symmetric about the point P as in the first embodiment shown in FIG. Further, in this cross-sectional shape, the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 along the gas channel arrangement direction, and the cooling water channel The sum of the channel width dimensions or the sum of the channel cross-sectional areas of the cooling water channels 18 along the 18 arrangement directions is equal to each other.

  The eighth embodiment shown in FIG. 8 is different from the seventh embodiment shown in FIG. 7 in the width and arrangement of the supply gas passage 3, the discharge gas passage 5, and the cooling water passage 18. Similarly, the formation of the fuel gas supply branch passage 11 and the fuel gas discharge branch passage 17 is opposite to this by the formation of the end faces 11a and 17a of the convex portions protruding on the opposite surface and the cooling water passage 18. The end surface 18a of each convex portion protruding on the side surface is a convex curved surface.

  Specifically, the radii of curvature RB1, RB2 of the end faces 11a, 17a and 18a corresponding to the fuel gas supply branch channel 11, the fuel gas discharge branch channel 17 and the cooling water channel 18 having the same channel width, respectively. And RL1 and RL2 are both 3 mm.

  FIG. 9 shows Comparative Example 1. In this comparative example 1, the flow widths B1 and B2 of the fuel gas supply branch flow path 11 and the fuel gas discharge branch flow path 17 are equal to each other, and the flow of the cooling water flow path 18 on the opposite surface is provided. It is thicker than the road width L1.

  Specifically, the flow path widths B1 and B2 of the fuel gas supply branch flow path 11 and the fuel gas discharge branch flow path 17 are 1.8 mm, and the flow path width L1 of the cooling water flow path 18 is 1.2 mm.

  For this reason, this comparative example 1 is the sum of the channel width dimensions of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 along the gas channel arrangement direction in the cross-sectional shape shown in FIG. Alternatively, the sum of the channel cross-sectional areas is larger than the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the cooling water channels 18 along the direction in which the cooling water channels 18 are arranged, and is different from each other.

  As a result, the fuel gas supply branch passage 11 and the fuel gas discharge branch flow formed on one surface of the separator 1 including the fuel gas supply main passage 9 and the fuel gas discharge main passage 15 shown in FIG. The total area in a plan view as viewed from the direction facing the one surface of the separator 17 in the entire path 17, that is, the gas flow path, and the direction facing the other surface of the separator 1 in the entire cooling water path 18. The total area in plan view is different from each other.

  FIG. 10 shows Comparative Example 2. The comparative example 2 is different from the comparative example 1 in that the end surface 18a of each convex portion that protrudes on the opposite side surface due to the formation of the cooling water flow path 18 is a convex curved surface having a curvature radius RL1 = RL2 = 2 mm. ing. Other configurations are the same as those of the first comparative example.

  Therefore, also in this comparative example 2, the sum of the channel width dimensions of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 or the channel in the cross-sectional shape of FIG. The sum of the cross-sectional areas is larger than the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the coolant channels 18 along the direction in which the coolant channels 18 are arranged, and is different from each other.

  FIG. 11 shows Comparative Example 3. In this comparative example 3, the end surfaces 11a and 17a of the convex portions projecting to the opposite surface by the formation of the fuel gas supply branch flow path 11 and the fuel gas discharge branch flow path 17 have the curvature radii RB1 = RB2 = 4 mm. This is different from Comparative Example 2 in that it is a convex curved surface. Other configurations are the same as those of the second comparative example.

  Therefore, also in this comparative example 3, the sum of the channel width dimensions of the fuel gas supply branch channel 11 and the fuel gas discharge branch channel 17 or the channel in the cross-sectional shape of FIG. The sum of the cross-sectional areas is larger than the sum of the channel width dimensions or the sum of the channel cross-sectional areas of the coolant channels 18 along the direction in which the coolant channels 18 are arranged, and is different from each other.

Next, in the separator 1 according to each of the above-described embodiments and comparative examples, the active area, that is, the area corresponding to the power generation portion is 10 cm ^2, and the separator 1 having the interdigitated flow path schematically shown in FIG. After press molding, the amount of warpage was measured. The amount of warpage here means that the separator 1 is placed on a plane, and the end of the separator 1 that comes into contact with the plane and the portion farthest from the plane out of the portion raised from the plane due to warpage. Interval.

  Furthermore, the separators 1 of these embodiments and comparative examples are used as fuel electrode side separators, and the oxygen agent electrode side separators have the same channel widths for the supply gas channel and the discharge gas channel. As the polymer electrolyte membrane, a perfluorocarbon polymer membrane having a sulfonic acid group (trade name; Nafion 112, DuPont Co., Ltd.) was applied with a platinum catalyst supported by carbon black as a gas diffusion electrode. Using carbon paper (TGP-H-090) manufactured by Toray Industries, Inc., as shown in FIG. 13, a large number of these are laminated on the end plate 29 having sufficient rigidity, and a surface pressure of 1 MPa is applied from both sides. The fuel cell stack 45 was configured by tightening, and the power generation characteristics were evaluated.

表１に示すように、セパレータ１の反り量は、セパレータ１の断面形状を点対称とした第１〜第３，第７，第８の各実施形態が小さく、中でも各端面１１ａ，１７ａ，１８ａを凸曲面とした第２，第３，第８の各実施形態が特に小さくなっている。 These evaluation results are shown in Table 1.

As shown in Table 1, the amount of warping of the separator 1 is small in each of the first to third, seventh, and eighth embodiments in which the cross-sectional shape of the separator 1 is point-symmetric, and among these, the end faces 11a, 17a, and 18a are particularly small. Each of the second, third, and eighth embodiments having a convex curved surface is particularly small.

  Compared to these embodiments, the amount of warping of the separator 1 according to the fourth to sixth embodiments is slightly larger, but is significantly smaller than those of Comparative Examples 1 to 3.

On the other hand, the power generation performance was evaluated by the electromotive force of the fuel cell when a current of 0.5 A / cm ² was taken out. Regarding the power generation characteristics, the first to sixth embodiments in which the flow width of the fuel gas supply branch flow path 11 of the separator 1 on the fuel electrode side is wider than the fuel gas discharge branch flow path 17 are excellent. Of these, the second, third, and fifth embodiments in which the end surfaces 11a, 17a, and 18a are convex curved surfaces and the sixth embodiment in which the end surface 18a is a convex curved surface are particularly excellent.

  The seventh and eighth embodiments are superior to Comparative Examples 1 to 3, although the power generation performance is slightly inferior to those of the first to sixth embodiments.

  Moreover, although the temperature of the reaction area center part of the fuel cell stack 45 at this time was measured, each of the fourth to eighth embodiments in which the channel width of the cooling water channel 18 is uniform as a whole is the lowest temperature. Excellent performance. Compared with each of these embodiments, the first to third embodiments having portions where the channel width of the cooling water channel 18 differs as a whole are slightly higher in temperature and inferior in cooling performance. Compared to ˜3, the temperature is low and the cooling performance is excellent.

  In addition, it is preferable that the curvature radius of the convex curved surface of each end surface 11a, 17a, 18a in each of the second, third, fifth, sixth, and eighth embodiments is 0.8 mm to 4.5 mm. It is more preferable to set it as 2 mm-4 mm. In this case, the end face 18a of the convex portion that is formed on the opposite surface of the cooling water flow path 18 and is in contact with the electrode surface of the solid electrolyte is formed into a convex curved surface, which can contribute to improvement in power generation performance.

  As described above, according to each embodiment of the present invention, the gas flow path (supply gas flow path 3, discharge gas flow path 5) and the cooling water flow path 18 are formed on both surfaces of the corrugated plate material, respectively. In addition, since the respective areas in a plan view of the gas flow paths 3 and 5 and the cooling water flow path 18 when viewed from the direction facing the separator 1 are made equal to each other, the gas flow paths 3 and 5 and the cooling water flow The tension on both surfaces of the separator 1 in which the path 18 is formed with unevenness can be equalized, and the warpage of the separator 1 can be reduced.

  As a result, the assemblability of the fuel cell is improved, the non-uniform surface pressure between the electrode (MEA 27) and the separator 1 in the assembled fuel cell can be prevented, the total contact resistance can be reduced, and the variation in gas distribution can be reduced. The power generation characteristics can be improved.

  In each of the above-described embodiments, the separator 1 has a strength suitable for downsizing the fuel cell by forming a stainless steel plate subjected to corrosion-resistant and conductive surface treatment into a predetermined shape by press molding. 1 can be supplied at low cost.

  In each of the first to sixth embodiments, at least in the separator 1 on the fuel electrode side, the flow path width of the fuel gas supply branch flow path 11 is made larger than the flow path width of the fuel gas discharge branch flow path 17, or The cross-sectional area of the fuel gas supply branch channel 11 is configured to be larger than the cross-sectional area of the fuel gas discharge branch channel 17.

  Here, the fuel gas (hydrogen) becomes a proton on the electrode catalyst surface, and this proton passes through the electrolyte membrane and moves to the oxidant gas electrode side. In comparison, the amount of gas discharged from the fuel electrode side is reduced. For this reason, in each of the first to sixth embodiments, the flow width of the fuel gas discharge branch flow path 17 is narrower than that of the fuel gas supply branch flow path 11 as the amount of gas decreases. Accordingly, the separator 1 can be reduced in size.

  Further, in each of the fourth to sixth embodiments, since the channel width dimension of the cooling water channel 18 is made uniform as a whole, the cooling performance can be effectively maintained.

  Further, as shown in FIG. 14, a fuel cell stack 45 having high power generation efficiency using the separator 1 of the present invention is mounted in a small space of an automobile 47 and used as a power source. Contributes to improved energy efficiency, and at the same time improves the freedom of styling.

  In addition, this invention is not necessarily limited to each above-mentioned embodiment, It cannot be overemphasized that a various change is possible within the range of the technical idea as described in a claim.

It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 1st Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 2nd Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 3rd Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 4th Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 5th Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 6th Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 7th Embodiment of this invention. It is the schematic diagram which showed the cross-sectional shape of the separator for fuel cells by 8th Embodiment of this invention. 6 is a schematic diagram showing a cross-sectional shape of a fuel cell separator according to Comparative Example 1. FIG. 6 is a schematic view showing a cross-sectional shape of a fuel cell separator according to Comparative Example 2. FIG. 6 is a schematic view showing a cross-sectional shape of a fuel cell separator according to Comparative Example 3. FIG. It is a perspective view which shows the gas flow path shape of the separator for fuel cells by each embodiment and each comparative example. It is a disassembled perspective view of the fuel cell stack using the separator for fuel cells by each embodiment and each comparative example. (A) is a side view of an automobile equipped with a fuel cell stack using a fuel cell separator according to each embodiment and each comparative example, and (b) is a plan view thereof.

Explanation of symbols

1 Fuel Cell Separator 3 Supply Gas Channel (Gas Channel)
5 Discharge gas channel (gas channel)
7 Fuel gas supply hole (supply port)
11 Fuel gas supply branch channel (gas channel)
13 Fuel gas discharge hole (discharge port)
17 Fuel gas discharge branch channel (gas channel)
18 Cooling water flow path 18a End face of convex part in contact with electrode surface (convex curved surface)
45 Fuel cell stack 47 Automobile

Claims (14)

A gas flow path is provided to face each electrode surface on both sides of the solid electrolyte, and an oxidant gas or fuel gas is supplied to the surface facing this electrode surface, and a cooling water flow is provided on the opposite side to the electrode surface. In a fuel cell separator having a channel, a plate material is formed in a corrugated shape, and the gas flow path and the cooling water flow path are formed on both surfaces thereof, and the gas flow path and the cooling water flow path are opposed to the surface of the separator. A separator for a fuel cell, characterized in that each area in a plan view as viewed from the direction to be made equal to each other. The gas flow path includes a supply gas flow path having one end opened to the outside as a supply port for supplying oxidant gas or fuel gas to the electrode surface, and a discharge port for discharging oxidant gas or fuel gas from the electrode surface A discharge gas flow path having one end opened to the outside, and the supply gas flow path and the discharge gas flow path are provided independently of each other, and a plurality of gas flow paths are alternately arranged. The fuel cell separator according to claim 1. The sum of the channel width dimensions or the sum of the channel cross-sectional areas along the arrangement direction of the supply gas channel and the discharge gas channel is calculated on the surface opposite to the gas channel. 3. The sum of the passage width dimensions or the sum of the passage cross-sectional areas along the arrangement direction of the cooling water passages formed between the passage and the discharge gas passage formation is equal to the sum of the passage cross-sectional areas. The fuel cell separator as described. At least on the side where the fuel gas circulates in the gas flow path, the sum of the flow path dimensions of the supply gas flow path or the total cross-sectional area of the gas flow path is the sum of the flow path width dimensions of the discharge gas flow path. 4. The fuel cell separator according to claim 3, wherein the separator is larger than the sum of the cross-sectional areas of the flow paths. The flow width or cross-sectional area of the cooling water flow path formed adjacent to the supply gas flow path and the discharge gas flow path on the opposite side is defined as the supply gas flow path and the discharge gas. The fuel cell separator according to any one of claims 2 to 4, wherein the fuel cell separator is equivalent to a flow path. 6. The separator for a fuel cell according to claim 5, wherein the cooling water flow paths are alternately arranged with narrow and wide flow paths. 7. The fuel cell separator according to claim 5, wherein a cross-sectional shape perpendicular to the gas flow direction of the gas flow path is point-symmetric with respect to a center portion in the arrangement direction of the gas flow paths. . 8. The fuel cell separator according to claim 1, wherein the cooling water passage has a uniform passage width as a whole. 9. The fuel cell according to claim 1, wherein an end surface of a convex portion that is formed on a surface opposite to the cooling water flow path and is in contact with an electrode surface of the solid electrolyte is a convex curved surface. Separator. 10. The fuel cell separator according to claim 9, wherein a radius of curvature of the convex curved surface is set to 0.8 mm to 4.5 mm. 11. The fuel cell separator according to claim 10, wherein the curvature radius of the convex curved surface is 2 mm to 4 mm. The fuel cell separator according to any one of claims 1 to 11, wherein the gas flow path and the cooling water flow path are formed by press-molding a stainless steel plate subjected to a corrosion-resistant and conductive surface treatment. A fuel cell comprising the fuel cell separator according to any one of claims 1 to 12. A fuel cell vehicle comprising a fuel cell stack configured by stacking a plurality of single cells of the fuel cell according to claim 13 and mounting the fuel cell stack as a power source.

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