JP5029813B2 - Fuel cell separator - Google Patents

Description

  The present invention relates to a fuel cell separator. More specifically, the present invention relates to an improvement in the structure of a separator constituting a fuel cell.

  Many separators for fuel cells are provided with integral fluid flow paths on the front and back sides and configured such that coolant such as cooling water (LLC) flows through the gap when the separators are overlapped. ing. In addition, as such a separator, for example, a separator having a flow path portion composed of about several tens of fluid flow paths and a distribution flow path for allowing cooling water to flow evenly in the plurality of fluid flow paths is proposed. (For example, refer to Patent Document 1).

It is important that the distribution channel in such a separator has a structure that ensures electrical contact (conduction) between the separators and between the separator and the membrane-electrode assembly while distributing fluid (for example, cooling water) evenly. is there. Therefore, conventionally, a separator having a structure in which protrusions on the front surface and protrusions on the back surface of the separator are alternately arranged so that the protrusions of adjacent separators face each other has been proposed.
JP-A-2005-243651

  However, the separator having the above-described structure does not have sufficient fluid distribution capacity (sometimes referred to as flow distribution in this specification) to a plurality of fluid flow paths, and the flow rate may vary. For example, if the flow rate of the cooling water varies for each flow path, the temperature in the cell surface increases, and the power generation performance may decrease.

  In view of the above, an object of the present invention is to provide a fuel cell separator in which the flow rate of the cooling water is prevented from varying for each flow path, and thus the power generation performance of the fuel cell can be prevented from being lowered. .

  In the distribution flow path described above, it is desirable that the cooling water is evenly distributed. In order to achieve this, there is also a structure in which the cooling water inlet side manifold and the outlet side manifold are arranged on the diagonal of the separator so that the cooling water spreads over the entire separator. However, as described above, when the protrusions are formed on both surfaces of the separator and the fluid is allowed to flow on each of the both surfaces, the flow channel depth in the distribution flow channel is the same as that in the flow channel portion formed in a wave shape. It becomes about half of the channel depth. In this case, since the fluid flow path portion has a smaller pressure loss than the distribution flow path, the coolant flow rate in the flow path close to the inlet side manifold and the outlet side manifold located diagonally tends to increase (see FIG. 7). In this regard, for example, in Japanese Patent Application Laid-Open No. 2000-251913 and Japanese Patent Publication No. 2002-539583, a fuel cell is proposed in which the cross-sectional area of the fluid flow path is changed between the anode side and the cathode side. It is difficult to improve the flow distribution only by changing. The present inventor, who has repeatedly studied with reference to an actual measurement example of the cooling water flow rate (FIG. 7), has obtained new knowledge that leads to the solution of such a problem.

  The present invention is based on such knowledge, and includes a plurality of refrigerant channels for circulating the refrigerant on one surface, a refrigerant inlet side manifold and a refrigerant outlet side manifold for supplying or discharging the refrigerant, and the refrigerant In the separator for a fuel cell having a structure including an inlet side manifold and a refrigerant distribution channel formed between the refrigerant outlet side manifold and the refrigerant channel, the refrigerant inlet side manifold and the refrigerant outlet side manifold are respectively The separator is disposed on one side and the other side on both sides of the refrigerant flow direction, and the distribution channel is formed such that the refrigerant channel area is smaller toward the both sides of the separator in the refrigerant flow direction than the central part of the separator. It is said.

  In the separator having such a structure, the area of the distribution channel connected to the channel through which the refrigerant (for example, cooling water) easily flows is configured to be small. For this reason, since it becomes easier for the refrigerant to flow closer to the center of the separator than to both sides of the refrigerant flow direction where the pressure loss is large, the flow distribution of the refrigerant is improved, and the flow rate variation (bias) for each flow path is suppressed.

  In such a separator, it is preferable that the flow path area of the refrigerant is continuously changed from the center toward both sides of the refrigerant flow direction.

  The separator according to the present invention is a press metal separator in which a refrigerant distribution flow path and a fuel cell reaction gas distribution flow path are integrally formed on the front and back sides, and a reduced flow area in the refrigerant distribution flow path. Is the flow path area increase of the reactive gas distribution flow path on the back side of the separator. For example, in the case of a separator in which hydrogen gas (fuel gas) flows on one surface (front surface) side on the other surface (back surface) side of the refrigerant, the hydrogen on the back surface is reduced by the amount by which the refrigerant distribution channel area is reduced. It is possible to increase the gas distribution channel area.

  In addition, it is also preferable that the cross-sectional shape of the refrigerant distribution flow path that is formed at least in a flow path area smaller than that of other parts is substantially rectangular. For example, if the distribution channel formed by the two-stage protrusions is made to have a substantially rectangular cross section in this way, the shape becomes simple, and the shape of the pressing mold becomes simple as well.

  According to the present invention, it is possible to suppress the variation of the flow rate of the cooling water for each flow path. Therefore, it is possible to suppress a decrease in the power generation performance of the fuel cell.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 6 show an embodiment of the present invention. The separator 20 for the fuel cell 1 according to the present invention includes a cooling water flow path 36 composed of a plurality of concave grooves, an inlet side manifold 17a and an outlet side manifold 17b, and an inlet side manifold 17a and an outlet of the cooling water. The cooling water distribution channel 26 is formed between the side manifold 17 b and the cooling water channel 36. In this embodiment, the cooling water distribution channel 26 is formed such that the channel area becomes smaller toward the both sides in the refrigerant flow direction than the central portion of the separator 20 (see FIG. 5 and the like).

  In the embodiment described below, first, a schematic configuration of a fuel cell stack in which a cell (power generation cell) 2 and a plurality of cells 2 constituting the fuel cell 1 are stacked will be described, and then a separator 20 and a cooling water will be described. The structure of the distribution channel 26 will be described.

  FIG. 1 shows a schematic configuration of a cell 2 of a fuel cell 1 in the present embodiment. The cells 2 configured as shown in the figure are sequentially stacked to form a cell stack 3 (see FIG. 2). Further, in the fuel cell stack composed of the cell stack 3 or the like, for example, both ends of the stack are sandwiched between a pair of end plates 7, and a restraining member including a tension plate 8 is disposed so as to connect the end plates 7 to each other. In this state, a load in the stacking direction is applied and fastened (see FIG. 2).

  The fuel cell 1 configured by such a fuel cell stack or the like can be used in, for example, an in-vehicle power generation system of a fuel cell vehicle (FCHV; Fuel Cell Hybrid Vehicle), but is not limited thereto. It can also be used in power generation systems mounted on various mobile bodies (for example, ships, airplanes, etc.), self-propelled devices such as robots, and stationary power generation systems.

  The cell 2 includes an electrolyte, specifically, a membrane-electrode assembly (hereinafter referred to as MEA; Membrane Electrode Assembly) 30 and a pair of separators 20 that sandwich the MEA 30 (in FIGS. 1 and 4, etc., indicated by reference numerals 20a and 20b, respectively). Etc.) (see FIG. 1). The MEA 30 and the separators 20a and 20b are formed in a substantially rectangular plate shape. Further, the MEA 30 is formed so that its outer shape is smaller than the outer shape of each separator 20a, 20b.

  The MEA 30 includes a polymer electrolyte membrane (hereinafter also simply referred to as an electrolyte membrane) 31 made of a polymer material ion exchange membrane, and a pair of electrodes (an anode side diffusion electrode and a cathode side diffusion electrode) sandwiching the electrolyte membrane 31 from both sides. 32a and 32b (see FIG. 1). The electrolyte membrane 31 is formed larger than the electrodes 32a and 32b. The electrodes 32a and 32b are joined to the electrolyte membrane 31 by, for example, a hot press method while leaving the peripheral edge portion 33.

  The electrodes 32a and 32b constituting the MEA 30 are made of, for example, a porous carbon material (diffusion layer) carrying a catalyst such as platinum attached to the surface thereof. One electrode (anode) 32a is supplied with hydrogen gas as a fuel gas (reactive gas), and the other electrode (cathode) 32b is supplied with an oxidizing gas (reactive gas) such as air or an oxidant. An electrochemical reaction is generated in the MEA 30 by the gas, and the electromotive force of the cell 2 is obtained.

  The separator 20 (20a, 20b) is made of a gas impermeable conductive material. Examples of the conductive material include carbon and a hard resin having conductivity, and metals such as aluminum and stainless steel. The base material of the separator 20 (20a, 20b) of the present embodiment is formed of a plate-like metal (metal separator), and a film having excellent corrosion resistance is formed on the surface of the base material on the electrodes 32a, 32b side. (For example, a film formed by gold plating) is formed.

  Further, a groove-like flow path constituted by a plurality of concave portions is formed on both surfaces of the separators 20a and 20b. These flow paths can be formed by press molding in the case of the separators 20a and 20b of the present embodiment in which the base material is formed of, for example, a plate-like metal. The groove-shaped flow path formed in this way constitutes an oxidizing gas flow path 34, a hydrogen gas flow path 35, or a cooling water flow path 36. More specifically, a gas channel 35 for hydrogen gas is formed on the inner surface of the separator 20a on the electrode 32a side, and a cooling water channel 36 is formed on the back surface (outer surface) ( (See FIG. 1). Similarly, a gas flow path 34 for oxidizing gas is formed on the inner surface on the electrode 32b side of the separator 20b, and a cooling water flow path 36 is formed on the back surface (outer surface) (see FIG. 1). . For example, in the case of the present embodiment, regarding the two adjacent cells 2, 2, when the outer surface of the separator 20 a of one cell 2 and the outer surface of the separator 20 b of the cell 2 adjacent to this are combined, The channel 36 is integrated so that a channel having a rectangular or honeycomb cross section is formed.

  Furthermore, as described above, the separators 20a and 20b have a relationship in which at least the uneven shape for forming a fluid flow path is reversed between the front surface and the back surface. More specifically, in the separator 20a, the back surface of the convex shape (convex rib) forming the hydrogen gas gas flow path 35 is a concave shape (concave groove) forming the cooling water flow path 36, and the gas flow path The back surface of the concave shape (concave groove) forming 35 is a convex shape (convex rib) forming the cooling water channel 36. Furthermore, in the separator 20b, the back surface of the convex shape (convex rib) that forms the gas flow path 34 of the oxidizing gas has a concave shape (concave groove) that forms the cooling water flow path 36, and the concave that forms the gas flow path 34. The back surface of the shape (concave groove) is a convex shape (convex rib) forming the cooling water flow path 36.

  Further, in the vicinity of the longitudinal ends of the separators 20a and 20b (in the case of this embodiment, in the vicinity of one end shown on the left side in FIG. 1), the manifold 15a on the inlet side of the oxidizing gas, hydrogen gas An outlet side manifold 16b and a cooling water inlet side manifold 17a are formed. For example, in the case of this embodiment, these manifolds 15a, 16b, and 17a are formed by substantially rectangular or trapezoidal holes provided in the respective separators 20a and 20b, or long and thin rectangular through holes having semicircular ends (FIG. 1). Etc.). Further, an oxidizing gas outlet side manifold 15b, a hydrogen gas inlet side manifold 16a, and a cooling water outlet side manifold 17b are formed at opposite ends of the separators 20a and 20b. In the case of this embodiment, these manifolds 15b, 16a, and 17b are also formed by a substantially rectangular or trapezoidal shape, or a long and narrow rectangular through hole having semicircular ends (see FIG. 1). In FIG. 2, the symbols of the manifolds are shown in a form in which the suffixes a and b are omitted.

  Of the manifolds as described above, the inlet side manifold 16a and the outlet side manifold 16b for the hydrogen gas in the separator 20a are connected via the inlet side communication passage 61 and the outlet side communication passage 62 formed in the separator 20a. Each communicates with a gas flow path 35 of hydrogen gas. Similarly, the inlet side manifold 15a and the outlet side manifold 15b for the oxidizing gas in the separator 20b are each formed of an oxidizing gas via an inlet side connecting passage 63 and an outlet side connecting passage 64 formed in the separator 20b. It communicates with the flow path 34 (see FIG. 1). Further, the inlet side manifold 17a and the outlet side manifold 17b of the cooling water in each separator 20a, 20b are respectively connected via an inlet side communication passage 65 and an outlet side communication passage 66 formed in each separator 20a, 20b. It communicates with the cooling water flow path 36. With the configuration of the separators 20a and 20b as described above, the cell 2 is supplied with oxidizing gas, hydrogen gas, and cooling water. As a specific example, when the cells 2 are stacked, for example, hydrogen gas passes from the inlet side manifold 16a of the separator 20a through the communication passage 61 and flows into the gas flow path 35, and is supplied to the power generation of the MEA 30. After that, the fluid passes through the communication passage 62 and flows out to the outlet side manifold 16b.

  In the present embodiment, the cooling water inlet-side manifold 17a and the outlet-side manifold 17b are respectively arranged on one side and the other side of the separator 20 in the cooling water flow direction (see FIGS. 1 and 3). . That is, in this embodiment, the inlet side manifold 17a and the outlet side manifold 17b of the cooling water are arranged on the diagonal line of the separator 20 so that the cooling water can easily spread over the separator 20 over the entire surface. .

  The first seal member 13a and the second seal member 13b are both formed of a plurality of members (for example, four independent small rectangular frames and a large frame for forming a fluid flow path). (See FIG. 1). Among these, the first seal member 13a is provided between the MEA 30 and the separator 20a. More specifically, a part of the first seal member 13a is a peripheral portion 33 of the electrolyte membrane 31 and a gas flow path 35 of the separator 20a. It is provided so that it may interpose between the surrounding parts. The second seal member 13b is provided between the MEA 30 and the separator 20b. More specifically, a part of the second seal member 13b is a peripheral portion 33 of the electrolyte membrane 31 and the gas channel 34 of the separator 20b. It is provided so as to be interposed between the surrounding portions.

  Further, a plurality of members (for example, four independent small rectangular frames and a large frame for forming a fluid flow path) are formed between the separators 20b and 20a of the adjacent cells 2 and 2. A third seal member 13c is provided (see FIG. 1). The third seal member 13c is provided so as to be interposed between a portion around the cooling water passage 36 in the separator 20b and a portion around the cooling water passage 36 in the separator 20a, and seals between them. It is.

  In addition, as the first to third seal members 13a to 13c, an elastic body (gasket) that seals a fluid by physical contact with an adjacent member, or an adhesive that is bonded by chemical bonding with an adjacent member. An agent or the like can be used. For example, in this embodiment, a member that is physically sealed by elasticity is employed as each of the seal members 13a to 13c, but instead, a member that is sealed by a chemical bond such as the adhesive described above may be employed.

  The frame-shaped member 40 is a member made of, for example, resin (hereinafter also referred to as a resin frame) that is sandwiched between the separators 20a and 20b together with the MEA 30. For example, in this embodiment, a thin frame-shaped resin frame 40 is interposed between the separators 20a and 20b, and the resin frame 40 sandwiches at least a part of the MEA 30, for example, a portion along the peripheral edge 33 from the front side and the back side. I have to. The resin frame 40 provided in this way functions as a spacer between the separators 20 (20a, 20b) that supports the fastening force, functions as an insulating member, and as a reinforcing member that reinforces the rigidity of the separator 20 (20a, 20b). Demonstrate the function.

  Next, the configuration of the fuel cell 1 will be briefly described (see FIG. 2). The fuel cell 1 according to the present embodiment includes a cell stack 3 formed by stacking a plurality of cells 2, and sequentially heat-insulating cells outside the cells (end cells) 2 and 2 located at both ends of the cell stack 3. 4 and a terminal plate 5 with an output terminal 5a, an insulator (insulating plate) 6, and an end plate 7. A predetermined compressive force in the stacking direction is applied to the cell stack 3 by a tension plate 8 that is bridged so as to connect both end plates 7. Further, a pressure plate 9 and a spring mechanism 9a are provided between the end plate 7 on one end side of the cell stack 3 and the insulator 6, so that the fluctuation of the load acting on the cell 2 is absorbed. ing.

  The heat insulation cell 4 has a heat insulation layer formed of, for example, two separators and a seal member, and plays a role of suppressing heat generated by power generation to be radiated to the atmosphere. That is, in general, the temperature of the end portion of the cell stack 3 is likely to be lowered by heat exchange with the atmosphere, and thus heat exchange (heat dissipation) is suppressed by forming a heat insulating layer at the end of the cell stack 3. Has been done. As such a heat insulating layer, for example, there is a structure in which a heat insulating member 10 such as a conductive plate is sandwiched between a pair of separators similar to those in the cell 2 instead of the membrane-electrode assembly. The heat insulating member 10 used in this case is more suitable as it has better heat insulating properties. Specifically, for example, a conductive porous sheet or the like is used. Moreover, an air layer is formed by sealing the circumference | surroundings of such a heat insulation member 10 with a sealing member.

  The terminal plate 5 is a member that functions as a current collecting plate, and is formed in a plate shape from a metal such as iron, stainless steel, copper, or aluminum. The surface of the terminal plate 5 on the heat insulating cell 4 side is subjected to a surface treatment such as a plating treatment, and the contact resistance with the heat insulating cell 4 is ensured by the surface treatment. Examples of the plating include gold, silver, aluminum, nickel, zinc, tin, and the like. For example, in this embodiment, tin plating is performed in consideration of conductivity, workability, and low cost.

  The insulator 6 is a member that functions to electrically insulate the terminal plate 5 from the end plate 7 and the like. In order to fulfill such a function, the insulator 6 is formed in a plate shape from a resin material such as polycarbonate.

  The end plate 7 is formed in a plate shape with various metals (iron, stainless steel, copper, aluminum, etc.) like the terminal plate 5. For example, in the present embodiment, the end plate 7 is formed using copper, but this is merely an example, and the end plate 7 may be formed of another metal.

  The tension plate 8 is provided so as to bridge between the end plates 7 and 7 and is disposed so that, for example, a pair is opposed to both sides of the cell stack 3 (see FIG. 2). The tension plate 8 is fixed to the end plates 7 and 7 with bolts or the like, and maintains a state in which a predetermined fastening force (compression force) is applied in the stacking direction of the single cells 2. An insulating film is formed on the inner surface of the tension plate 8 (the surface facing the cell stack 3) in order to prevent leakage or sparks. Specifically, the insulating film is formed by, for example, an insulating tape attached to the inner surface of the tension plate 8 or a resin coating applied so as to cover the surface.

  Next, the structure of the separator 20 and the distribution channel will be described (see FIG. 3 and the like).

  The distribution channel 21 is formed between the manifold 15a and the like and the gas channels 34 and 35 or the cooling water channel 36, and the fluid flowing in from the manifold 15a and the like is supplied to the gas channels 34 and 35 or the cooling water channel. It distributes to each concave groove which comprises 36, or the fluid which flowed out from each concave groove joins, and flows out from the manifold 15b etc. FIG. In FIG. 3 and FIG. 4, the cooling water distribution flow path connected to the cooling water flow path 36 is indicated by reference numeral 26. Further, in FIG. 4, an oxidant gas distribution channel connected to the oxidant gas channel 34 is indicated by reference numeral 24, and a hydrogen gas distribution channel connected to the hydrogen gas gas channel 35 is indicated by reference numeral 25 ( (See FIG. 4).

  In this embodiment, portions where the fluids flowing out from the respective concave grooves join are also called distribution channels 24 to 26. In other words, the distribution channels 24 to 26 in this case do not substantially distribute the fluid, but have a symmetrical structure and can flow the fluid in any direction, so that the distribution channels (Refer to FIG. 3).

  In the separator 20b, a protrusion 52 protruding in a substantially circular shape toward the MEA 30 and a protrusion 51 protruding in a substantially circular shape toward the facing separator 20a are alternately formed at equal intervals (see FIG. 4). . A dimple-like recess is integrally formed on the back side of each of the protrusions 51 and 52. Each of the protrusions 51 and 52 functions as a spacer that contacts the opposing separator 20a or MEA 30 to secure a space for forming the oxidizing gas distribution channel 24 and the cooling water distribution channel 26, and at the time of cell stacking, the separator 20b. It acts to receive the fastening load that acts on (see FIG. 4).

  On the other hand, the separator 20a is formed so that protrusions 42 that protrude in a substantially circular shape toward the MEA 30 and protrusions 41 that protrude in a generally circular shape toward the opposing separator 20b are alternately spaced at equal intervals (FIG. 4). reference). A dimple-like recess is integrally formed on the back side of each protrusion 41, 42 (in FIG. 3, the dimple-like recess formed on the back side of the protrusion 42 is indicated by reference numeral 42d). Each of the protrusions 41 and 42 functions as a spacer that contacts the opposing separator 20b or MEA 30 to secure a space for forming the hydrogen gas distribution flow path 25 and the cooling water distribution flow path 26, and at the time of cell stacking, the separator 20a. It acts to receive the fastening load that acts on (see FIG. 4).

  In the separator 20 (20a, 20b) described above, the oxidizing gas that has flowed from the inlet side manifold 15a of the oxidizing gas flows through the distribution flow path 24, flows through the gas flow path 34 of the oxidizing gas, and further, the distribution flow path 24 on the opposite side. And flows out from the outlet side manifold 15b. Similarly, the hydrogen gas that has flowed in from the inlet side manifold 16a of hydrogen gas flows through the distribution channel 25, flows through the gas channel 35 of hydrogen gas, and further flows through the distribution channel 25 on the opposite side, from the outlet side manifold 16b. leak. Further, the cooling water flowing in from the inlet side manifold 17a of the cooling water flows through the distribution channel 26, flows through the cooling water channel 36, further flows through the distribution channel 26 on the opposite side, and flows out from the outlet side manifold 17b.

  Here, in the case of the distribution flow path 26 having a uniform flow path area, a large amount of cooling water flows into the flow paths close to the cooling water inlet side manifold 17a and the outlet side manifold 17b that are positioned diagonally, and cooling in the central portion. The water flow rate may be extremely low (see FIG. 7 shown as a reference). In this case, the distribution characteristics of the cooling water are insufficient, and cooling with the cooling water is not sufficiently performed due to the variation in the flow rate, and as a result, the power generation performance of the fuel cell 1 may be deteriorated.

  In this regard, in the present embodiment, the cooling water distribution flow path 26 is formed so that the flow path area becomes smaller toward the both sides in the cooling water flow direction (see the arrow in FIG. 3) than the central portion of the separator 20. (See FIG. 5). That is, the distribution of the cooling water is improved by intentionally reducing the flow channel area of the distribution flow channel 26 connected to the cooling water flow channel 36 where a large amount of the cooling water easily flows (see FIG. 6). . In such a structure, the cooling water easily flows not only near both sides of the refrigerant flow direction where the pressure loss is large, but also near the center of the separator 20, thereby improving flow distribution and variation in flow rate for each flow path ( (Bias) is suppressed. The pressure loss referred to in this specification means that energy such as pressure of the fluid is consumed due to the shape of the fluid channel, the smoothness of the surface of the fluid channel, and the like. For example, in the case of the present embodiment, it can also be expressed as a differential pressure acting on the cooling water at the boundary portion between the cooling water distribution channel 26 and the cooling water channel 36.

  6 and 7 exemplify the distribution characteristics of the cooling water when the number of channels (concave grooves) of the cooling water channel 36 is 50. In addition, “upper stage” and “lower stage” in the figure represent the upper side and the lower side in the vertical direction, respectively. Incidentally, in many cases, the cooling water inlet-side manifold 17a is arranged at the lower stage (lower side) and the outlet-side manifold 17b is arranged at the upper stage (upper side), but the arrangement is not limited to this.

  Here, a specific example of a structure for improving flow distribution will be described. In the present embodiment, the protrusion 41 of the separator 20a is formed to have a larger diameter than the protrusion 51 of the opposing separator 20b (see FIG. 5). In such a case, the back side region (area) of the projection 41 is increased, and the back side region (area) of the adjacent projection 42 is relatively decreased. Therefore, the pressure loss of the fluid (cooling water) increases accordingly. If another expression is made using FIG. 3, the cooling water is less likely to flow in the portion where the gap between the adjacent protrusions 41, 41 is narrowly formed. Therefore, it is possible to improve the uneven flow distribution property that the flow rate increases toward both ends in the flow direction, and to suppress the variation (bias) in the flow rate for each flow path (see FIG. 6).

  Further, when the cooling water distribution channel 26 is formed to be small, the cross-sectional shape of the separator 20a (the cross-sectional shape of the protrusion 41 and the protrusion 42) is preferably substantially rectangular. For example, the separator 20b has a flat portion between the protrusion 51 and the protrusion 52 and has a two-step sectional shape, whereas the opposing separator 20a of the present embodiment has a substantially rectangular or trapezoidal sectional shape. The projection 41 and the projection 42 have a relatively simple wave shape in which the projection 41 and the projection 42 are continuously connected.

  Furthermore, when the cooling water distribution channel 26 is formed to be small, it is also preferable that the channel area of the distribution channel 26 is continuously changed from the central portion of the separator 20a toward both sides of the refrigerant flow direction. For example, in the present embodiment, only the cross-sectional shape of the VV line in FIG. 3 is shown (see FIG. 5), but the cross-sectional area increases toward the center of the VV line, and both ends (outside) of the VV line. The shape of the cooling water distribution flow path 26 is continuously changed so that the cross-sectional area decreases as the distance to () increases. In such a case, the flow distribution can be further improved by further suppressing variation (bias) in the flow rate (see FIG. 6).

  As described so far, according to the separator 20 (20a) of the present embodiment in which a part of the distribution flow path 26 is appropriately reduced, the distribution of the cooling water is improved and the flow rate variation (bias) for each flow path is improved. ) Can be suppressed, it is possible to suppress the power generation performance of the fuel cell 1 from being deteriorated. Moreover, if the flow distribution is improved by using CFD (computational fluid dynamics) analysis data, the flow rate variation (dispersion) degree in the conventional shape is 67.4, but in the case of this embodiment, it is 17.3. It has improved (refer FIG. 6, FIG. 7).

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the shape of the separator 20a is appropriately modified so that the decrease in the cooling water channel area is allocated to the increase in the hydrogen gas channel area (see FIG. 5). The shape may be modified as appropriate. In such a case, the decrease in the cooling water channel area can be assigned to the increase in the oxidation gas channel area. Alternatively, both separators 20a and 20b may be similarly deformed to have a symmetrical shape.

  Further, the shape of the separator 20 (20a) shown in the present embodiment is merely an example, and the shape is not particularly limited as long as the shape can appropriately reduce the cooling water flow rate. For example, the flow rate of the cooling water may be reduced by forming the groove portion of the separator 20 forming the distribution flow path 26 shallow, or the flow rate of the cooling water may be reduced by forming the groove portion of the separator 20 to be narrow. May be reduced.

It is a disassembled perspective view which shows the structural example of the cell of the fuel cell in this embodiment. It is a side view which shows the structural example of a fuel cell. It is a top view which shows the structural example by the side of the cooling water flow path of a separator. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along the line VV in FIG. It is a graph which shows an example of the cooling water flow rate for every flow path in the separator of this embodiment. It is a graph which shows an example of the cooling water flow rate for every flow path in the conventional separator as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Cell, 3 ... Cell laminated body, 17a ... Cooling water inlet side manifold (refrigerant inlet side manifold), 17b ... Cooling water outlet side manifold (refrigerant outlet side manifold), 20 (20a, 20b) ) Separator, 24 ... Oxidizing gas distribution channel (reaction gas distribution channel), 25 ... Hydrogen gas distribution channel (reaction gas distribution channel), 26 ... Cooling water distribution channel (refrigerant distribution) Flow path), 36 ... cooling water flow path (refrigerant flow path)

Claims (4)

A plurality of refrigerant flow paths for circulating the refrigerant on one surface; a refrigerant inlet side manifold and a refrigerant outlet side manifold for supplying or discharging the refrigerant; and the refrigerant inlet side manifold and the refrigerant outlet side manifold; In the separator for a fuel cell having a structure provided with the refrigerant distribution channel formed between the refrigerant channel,
The refrigerant inlet side manifold and the refrigerant outlet side manifold are respectively arranged on one side and the other side on both sides of the refrigerant flow direction of the separator,
The separator is characterized in that the flow path area of the refrigerant is formed smaller toward the both sides in the refrigerant flow direction than the central portion of the separator.   The separator according to claim 1, wherein the flow path area of the refrigerant continuously changes from the central portion toward both sides of the refrigerant flow direction.   The refrigerant distribution flow path and the fuel cell reactive gas distribution flow path are press-metal separators formed integrally with each other, and the flow path area decrease in the refrigerant distribution flow path is the back side of the separator. 3. The separator according to claim 1, wherein the amount of the reaction gas distribution channel is increased by an area of the flow path area.   4. The separator according to claim 1, wherein at least one of the refrigerant distribution channels having a channel area smaller than the other part has a substantially rectangular cross-sectional shape. 5.

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