Fuel-cell-stack manufacturing method and manufacturing device

A method is provided for manufacturing a fuel-cell stack that has a laminate including of a plurality of fuel cells that are laminated together. In each of these fuel cells, an MEA has an anode and a cathode joined respectively to the two sides of an electrolyte membrane is sandwiched between a pair of separators. The aforementioned method has the following steps: a sealing member layout step, in which fuel cells with sealing members applied at least between adjacent fuel cells are laminated together, forming a fuel cell module; and a pressure application step, in which pressure is applied to the fuel cell module in the lamination direction of the fuel cells, forming sealed regions from the sealing members. The lamination-direction thickness of the fuel cell module is controlled by controlling the amount of pressure applied to the fuel cell module in the pressure application step.

This application is a U.S. National stage application of International Application No. PCT/JP2014/057900, filed Mar. 20, 2014, which claims priority to Japanese Patent Application No. 2013-085251 filed in Japan on Apr. 15, 2013. The entire disclosure of Japanese Patent Application No. 2013-085251 is hereby incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a fuel cell stack manufacturing method and a manufacturing device.

Background Information

A fuel cell stack is obtained by laminating a plurality of fuel cell modules, which are obtained by laminating a predetermined number of fuel cells, to make a laminate that covers the side faces of the laminate with a chassis, disposing plates on both ends in the lamination direction and fastening them with bolts or the like. The area between a fuel cell and another fuel cell that configure a fuel cell module, as well as the area between fuel cell modules, is sealed so that fuel, oxidizing agents, and cooling water that flow inside of the laminate will not leak. The central portion, when viewing the fuel cell module in a planar view, is a region where fuel gas and oxidizing agents flow and where power generation occurs; therefore, the sealing member cannot be provided to this region, and thus, the sealing member is provided to the outer peripheral part of the fuel cell module.

In this manner, the sealing member is provided only to the outer peripheral part of the fuel cell module; as a result, there are cases in which the thickness of the module in the lamination direction is uneven between the outer peripheral part to which a sealing member is provided and the central portion to which a sealing member is not provided. If there is a difference between the thickness of the central portion and the thickness of the outer peripheral part of the module, there is the risk that a good sealing property cannot be obtained due to the sealing member being insufficiently compressed. Accordingly, the keeping the thickness of the module uniform between the central portion and the outer peripheral part is desirable. As a technique to keep the thickness of the module uniform, for example, there is that which disposes a gap-maintaining structure (a so-called spacer) on the outer periphery of a membrane electrode assembly, which is clamped by a separator, between the membrane electrode assembly and the separator (refer to Japanese Laid-Open Patent Application No. 2010-272474).

SUMMARY

When trying to regulate the thickness of the fuel cell module with a spacer, such as in Patent Document 1, if the spacer is formed to be thinner than expected due to dimensional variability, the outer peripheral part of the module will be more excessively crushed than expected to match the spacer. If the outer peripheral part of the module is excessively crushed and the sealed portion by the sealing member is formed, there are cases in which, even if a necessary number of fuel cell modules for the fuel cell stack are laminated and plates are disposed to clamp both ends in the lamination direction, the central portion will not be crushed to the thickness of the outer peripheral part; as a result, the thickness of the fuel cell module cannot be made to be uniform. In such a case, there is the problem that the sealing member is not sufficiently compressed due to the bulging of the central portion, and a good sealing property cannot be obtained.

Therefore, in order to solve the problems described above, an object of the present invention is to provide a fuel cell stack manufacturing method and a manufacturing device that are able to secure the compression amount of the sealing member disposed on the fuel cell module.

The present invention, which achieves the object described above, is a fuel cell stack manufacturing method comprising a fuel cell module in which are laminated a plurality of fuel cells, whose membrane electrode assembly is clamped by a pair of separators. The fuel cell stack manufacturing method according to the present invention comprises a sealing member layout step, in which a sealing member is disposed on the outer peripheral part of the end surfaces that face each other between at least one fuel cell and another adjacent fuel cell, and a fuel cell module is formed by laminating the fuel cells; the method also comprises a pressure application step in which pressure is applied to the fuel cell module in the lamination direction of the fuel cells, forming sealed regions from the sealing members. In the fuel cell stack manufacturing method according to the present invention, the lamination-direction thickness of the fuel cell module is controlled by controlling the amount of pressure applied to the fuel cell module.

In addition, the fuel cell stack manufacturing device according to the present invention comprises: a sealing member layout unit for disposing a sealing member on the outer peripheral part of end surfaces that face each other between at least one fuel cell and another adjacent fuel cell; a laminating unit that forms a fuel cell module by laminating the fuel cells to which the sealing member is disposed; a pressure application unit that applies pressure to the fuel cell module in the lamination direction of the fuel cells; and a control unit for controlling the operation of at least the pressure application unit. In the fuel cell stack manufacturing device according to the present invention, the lamination-direction thickness of the fuel cell module is controlled by the control unit controlling the amount of pressure that is applied to the fuel cell module via the pressure application unit.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be explained below, with reference to the appended drawings. The description below does not limit the technical scope or the meanings of the terms described in the Claims. The dimensional ratios in the drawings are exaggerated for the convenience of the explanation, and they are different from the actual ratios.

First Embodiment

FIG. 1AandFIG. 1Bare a time chart and a flowchart, respectively, illustrating the fuel cell stack manufacturing method according to the first embodiment of the present invention;FIG. 1Cis a flowchart illustrating in detail the module manufacturing step from the above-described manufacturing method.FIG. 2andFIG. 3are explanatory views illustrating the sealing member layout step in the laminate assembly step according to the first embodiment;FIG. 4is an explanatory view illustrating the pressure application step of the laminate; andFIG. 5andFIG. 6are explanatory views illustrating the formation (stacking) of the laminate.

The fuel cell stack manufacturing method according to the present invention generally comprises the manufacturing of the module (refer to the drawings and ST10inFIG. 1B), comprising a sealing member layout step (refer toFIG. 1A,FIG. 2, andFIG. 3) and the pressure application step (refer toFIG. 1AandFIG. 4); also included is an assembly step (refer to ST30inFIG. 1B,FIG. 5, andFIG. 6), in which the modules are laminated and fastened to form a stack. The details are described below.

FIG. 7is an explanatory view illustrating the fuel cell stack according to the embodiment.FIG. 8is an exploded perspective view illustrating the configuration of the fuel cell stack.FIG. 9Ais a cross-sectional view along the section line9-9ofFIG. 8, illustrating the cell structure of the fuel cell stack.FIG. 9Bis a cross-sectional view illustrating a modified example ofFIG. 9A.FIG. 10is a plan view illustrating the fuel cell module.

The fuel cell stack100according to the first embodiment, with reference toFIG. 7-FIG. 10, comprises a fuel cell30, in which a membrane electrode assembly (hereinafter referred to as an MEA)31, configured by joining an anode31band a cathode31con both sides of an electrolyte membrane31a, is clamped by a pair of separators32a,32b. The fuel cell30is configured as a fuel cell module40by, for example, laminating about eight cells. The fuel cell module40is configured as a laminate50by laminating two or more thereof. When manufacturing the fuel cell stack100, the first embodiment relates to a step in which a sealing member70is disposed between the MEA31and the separator32a, between the MEA31and the separator32b, and between the separator32aand the adjacent separator32bin order to apply a pressing load and to form a seal region. In addition, a sealing member80is disposed between the fuel cell modules40in a state of being attached to a plate member81. In the first embodiment, when forming a sealing member by pressing the laminate50, to which are disposed the sealing members70,80, the lamination direction thickness of the laminate50is controlled by controlling the load pressing on the laminate50. The details are described below.

First, the fuel cell stack100according to the present embodiment will be described. In the fuel cell stack100, a predetermined number of unit battery cells (fuel cells)30, which generate electromotive force via the reaction of an anode gas, such as hydrogen, and a cathode gas, such as oxygen, are laminated to make the fuel cell module40, and a predetermined number of the fuel cell modules40are laminated to form a laminate50, as illustrated inFIG. 8andFIG. 9A. However, the laminate50is not a necessary configuration and may be configured from one fuel cell module. A collector plate34, an insulating plate35, and an end plate36are disposed on both ends of the laminate50.

The fuel cell30comprises an MEA31, separators32a,32b, which are respectively disposed on both sides of the MEA31, and a frame33, as illustrated inFIG. 9A. Herein below, the separator that is disposed on the anode side of the MEA31is referred to as the anode separator32a, and the separator that is disposed on the cathode side is referred to as the cathode separator32b.

The MEA31comprises a cathode31c, an anode31b, and a solid polymer electrolyte membrane31a, which is a polymer electrolyte membrane that passes, for example, hydrogen ions, as illustrated inFIG. 9A. The MEA31is configured to have a laminated structure, in which the solid polymer electrolyte membrane31ais sandwiched from both sides thereof, by the anode31band the cathode31c. The anode31b, which comprises an electrode catalyst layer, a watering layer, and a gas diffusion layer, is formed into a thin plate shape. The cathode31c, which comprises an electrode catalyst layer, a watering layer, and a gas diffusion layer, is formed into a thin plate shape in the same way as the anode31b. The electrode catalyst layer of the anode31band the cathode31cincludes a polymer electrolyte and an electrode catalyst in which the catalyst component is held on a conductive carrier. The gas diffusion layer of the anode31band the cathode31cis formed from, for example, carbon paper, carbon felt, or the like.

The separators32a,32bare formed by forming a conductive metal plate with a thin plate thickness into a predetermined shape with a die. The separators32a,32bhave a waveform shape (a so-called corrugated shape) in which a convex portion and a concave portion are alternately formed in an active area that contributes to power generation (the area of the central portion that is in contact with the MEA)32c, as illustrated inFIG. 9A.

From the convex/concave shape of the anode separator32a, an anode gas flow channel37afor circulating the anode gas is formed in the area of the side that is in contact with the anode21b. Similarly, from the convex/concave shape of the cathode separator32b, a cathode gas flow channel37bis formed in the area of the side that is in contact with the cathode. In addition, the anode separator32aforms a cooling flow path37cfor a cooling medium, such as cooling water, for cooling the fuel cell module40on the surface on the opposite side of the side that is in contact with the anode31b. Similarly, the cathode separator32bforms a cooling flow path37cfor a cooling medium, such as cooling water, for cooling the fuel cell module40on the surface on the opposite side of the side that is in contact with the cathode31c.

The frame33is a rectangular plate-like member made of a resin or the like having electrical insulating properties. The frame33holds the outer periphery of the MEA31.

The collector plate34is joined to both ends of the laminate50. The collector plate34is formed from a conductive member that does not permeate gas, such as dense carbon. A protrusion34ais formed on the collector plate34, which is configured so that the power that is collected by the collector plate34can be transferred outside.

The insulating plate35is formed into a plate shape made of rectangles and is disposed at both ends of the laminate50to insulate the collector plate34.

The end plate36is made of, for example, metal, and a pair thereof hold a pair of insulating plates35while biasing them from both sides. The separators32a,32b, the frame33, the collector plate34, the insulating plate35, the end plate36, and a plate member81, which are mentioned below, are formed into a plate shape made of rectangles; a cathode gas inlet38a, a medium inlet38b, and an anode gas inlet38care formed on one end in the longitudinal direction by through-holes, and an anode gas outlet38d, a medium outlet38e, and cathode gas outlet38fare formed on the other end in the longitudinal direction by through-holes.

The tension plates39a,39bare flat plate members that cover the side surface corresponding to the long side of the fuel cell30, from the side surface of the fuel cell30in the lamination direction. Flange portions are provided on both ends of the tension plates39a,39bin the lamination direction of the cells, and the fuel cell30is pressurized by being fastening to the end plate36from both ends with a bolt43or the like.

The tension guides39c,39dare members with a C-shaped cross section that are attached to the surface that is perpendicular to the tension plates39a,39b. The positional displacement of the fuel cell30in the horizontal direction is prevented with the tension guides39c,39dbeing attached to the side surface, corresponding to the short side of the fuel cell30inFIG. 5andFIG. 6.

The sealing member70is disposed between the MEA31and the anode separator32a, between the MEA31and the cathode separator32b, and between the anode separator32aand the adjacent cathode separator32b, as illustrated inFIG. 9A. The material of the sealing member70is not particularly limited, and may be, for example, a thermosetting resin.

The plate member81is disposed between a fuel cell module40and an adjacent fuel cell module40. A sealing member80is provided to the outer peripheral part of both surfaces of the plate member81. The material of the sealing member80is not particularly limited and may be an elastic member such as rubber.

The sealing member70seals between the MEA31and the anode separator32a, where fuel flows, between the MEA31and the cathode separator32b, where an oxidizing agent flows, and between the separator32aand the separator32b, where the cooling medium flows, inside of the fuel cell module40. In addition, the cooling medium that flows between fuel cell modules40is sealed by the sealing member80being disposed between the fuel cell modules40. The present Specification disposes the sealing member70between the MEA31and the anode separator32aand between the MEA31and the cathode separator32b, which configure the fuel cell module40, and disposes the sealing member80between adjacent fuel cell modules40, corresponding to disposing the sealing member on the outer peripheral part of the end surfaces that face each other between adjacent fuel cells. The position of the sealing member is not limited toFIG. 9A. Fuel, an oxidizing agent, and a cooling medium may be sealed by disposing the sealing member70between the frames33of the adjacent MEA31, as illustrated inFIG. 9B. This is because the fuel, the oxidizing agent, and the cooling medium that flow inside of the fuel cell module can be sealed, even if the sealing member70is disposed as shown inFIG. 9B.

Next, the laminate assembly device in which a plurality of fuel cell modules according to the present embodiment are laminated will be described. The laminate assembly device200and the mounting device300according to the first embodiment are a part of the manufacturing device of the fuel cell stack; since the other device configurations in the manufacturing device of the fuel cell stack are well known, the explanations thereof are omitted.FIG. 11is a schematic perspective view, illustrating the laminate assembly device according to the first embodiment;FIG. 12is a perspective view illustrating a state in which the fuel cell module is clamped by a jig.FIG. 13is an explanatory view illustrating a case in which the laminate is pressed and a case in which the laminate is not pressed by the pressure application unit.FIG. 14andFIG. 15are explanatory views showing the formation of the seal region by the pressing via the fuel cell module.

The assembly device200of the laminate50comprises a coating unit20for coating the sealing member70(corresponding to the sealing member layout unit); a lamination unit90that forms the fuel cell module40and the laminate50by laminating an MEA31; separators32a,32band a plate member81; a pressure application unit10that presses the fuel cell module40from the lamination direction of the fuel cell30, in the fuel cell module40; and a control unit60that controls the operation of at least the pressure application unit10(refer toFIG. 2-FIG. 4andFIG. 11).

The pressure application unit10comprises a pressing jig11that presses the laminate50by approaching and separating in the lamination direction of the laminate50, as well as a receiving jig12that receives the laminate50that has been pressed by the pressing jig11by setting the laminate50thereon. In addition, the pressure application unit10comprises an elastic member13that is connected to the pressing jig11(corresponding to the buffer member), a detection unit14for detecting the pressing load that the pressing jig11applies, a retaining unit15for retaining the state in which the laminate50is pressed by the pressing jig11and the receiving jig12, and a pressing member16.

The pressing jig11approaches and separates from the receiving jig12in conjunction with the movement of the pressing member16, which generates a force to move the pressing jig11toward the receiving jig12. The pressing jig11has a sufficiently larger area than the area of the laminate50when viewing the laminate50in plain view; in the first embodiment, the pressing surface is formed to be flat.

The MEA31and the separators32a,32bare set on the receiving jig12, whose placement surface is formed to be flat and which is formed to have an area that is the same as the pressing surface of the pressing jig11. In addition, insertion holes for inserting connecting bolts17, which position the pressing jig11and the receiving jig12, are formed on the four corners of the pressing jig11and the receiving jig12.

The retaining unit15comprises connecting bolts17that are inserted in the insertion holes that are provided to the pressing jig11and the receiving jig12and connect the pressing jig11and the receiving jig12, along with nuts18that are fastened to the threaded portions of the connecting bolts17. The pressing jig11and the receiving jig12are positioned by fastening the nut18to the connecting bolt17, and the adjustment of the gap and the retention of the gap between the pressing jig11and the receiving jig12are carried out.

The elastic member13prevents cracks from forming on the laminate50due to an excessive force being applied abruptly to the laminate50, when pressing the laminate50with a predetermined load. In addition, if there is a temperature change when curing by applying the sealing member70, the sealing member70causes shrinkage, etc., and the load that is applied to the laminate50fluctuates; however, by providing the elastic member13, the change in the load of the sealing member70due to a temperature change is released, and preventing the generation of flaws, etc., on the laminate50due to stress concentration is possible.

FIG. 17is an explanatory view illustrating a modified example of a jig structure in the laminate assembly device according to the first embodiment. In the first embodiment, the elastic member13is configured by a coil spring, as illustrated inFIG. 4, etc.; however, other than the above, the elastic member may also be configured by a plate spring13a, as illustrated inFIG. 15. By using a configuration such as a coil spring or a plate spring, forming the seal region by the sealing members70,80with a simple configuration, without damaging the laminate50, becomes possible.

The detection unit14is a member for detecting the pressing load with which the pressing jig11presses the laminate50; while a, a load cell is used in the present embodiment, the embodiment is not limited thereto.

In addition, the separators32a,32bthat configure the MEA31in the fuel cell30have the uneven, so-called corrugated shape32c, as described above. Since the central portion41of the fuel cell module illustrated inFIG. 10, in which the fuel cells30are laminated, corresponds to the power generation portion, the sealing member70cannot be applied thereto, and the sealing member70is applied only on the outer peripheral part42. Accordingly, if load is applied upon curing the sealing member70, stress is likely to be concentrated at the boundary of the outer peripheral part42to which the sealing member70is applied and the central portion41to which the sealing member70is not applied. In contrast, by providing a corrugated shape32cto the central portion41, which is the power generation portion, the load is absorbed by the corrugated shape32cin the same way as the elastic member13; damage to the laminate50is prevented by preventing stress from being concentrated at the boundary of the central portion41and the outer peripheral part42; and managing the thickness of the laminate50by the pressing load becomes possible.

The coating unit20comprises an applicator21, an arm22for moving the applicator21in a set direction, and a rail23for moving the arm22in a direction that intersects the direction in which the applicator21moves.

An example of an applicator21is, for example, a gun-shaped, injection-type one; however, the applicator is not limited thereto. The arm22positions the applicator21to predetermined positions of the MEA31and the separators32a,32b, which configure the laminate50, by movably attaching the applicator21and moving the applicator21. The movement of the applicator21can be realized by, for example, providing rotatable rollers to the applicator21and by providing an arm rail to the arm22, which becomes a path for the rollers of the applicator21; however, the configuration is not limited thereto.

The rail23is, for example, installed on the sidewall of the assembly device200and is disposed in a direction that is different from the movement direction of the applicator21to be a path that allows for the movement of the arm22. Accordingly, if the applicator21and the arm22are moved; the applicator21can be disposed in a predetermined position of the MEA31or the separators32a,32b, by combining the movement direction of the applicator21and the movement direction of the arm22; and the sealing member70can be applied. The movement of the arm22can be realized by providing a rotatable arm roller to the arm22and having the arm roller move the rail23; however, the configuration is not limited thereto.

The lamination unit90is configured from the MEA31and the separators32a,32b, which configure the laminate50, and a hand robot on which the plate member81is set, as illustrated inFIG. 3. Besides the above, the lamination work may be performed, for example, manually.

The control unit60is configured from a CPU, a RAM, a ROM, and an I/O interface, etc., and this unit controls the operation of the pressure application unit10, the coating unit20, and the lamination unit50; however, this unit may also be configured to control only the operation of the pressure application unit10.

The assembly device300, which forms the laminate, comprises a supporting platform110, a reference table120(corresponding to the clamping member), pillars131,132, a pillar spacing adjustment jig150, reference side pillars161,162, a control unit180, a load application member310(corresponding to the clamping member), and a pressing member320(corresponding to the clamping member). The reference table120is placed on the supporting platform110; constituent components of the fuel cell stack, such as the fuel cell module40and the plate member81, are stacked on the reference table120. The stacked constituent components of the fuel cell stack are positioned and aligned with the pillars131,132being inserted in the positions of the medium inlet or the medium outlet. The pillar spacing adjustment jig150is placed on the reference side pillars161,162. The pillar spacing adjustment jig150adjusts the gap between the pillar131and the pillar132. The load application member310and the pressing member320are controlled by the control unit180, clamping the constituent components of the fuel cell stack along with the reference table120, in a state in which the laminate50, the collector plate34, the insulating plate35, and the end plate36are stacked; thus, the pressing load is applied. In this state, the fuel cell stack is completed by attaching and bolt-fastening the tension plates39a,39band the tension guides39c,39d.

Next, the laminate assembly method according to the present embodiment will be described. The laminate assembly step according to the first embodiment comprises a sealing member layout step, in which the sealing member70is applied to the outer peripheral part42of the separator32a, which configures the laminate50, the MEA31is stacked, the separator32bis stacked, the sealing member70is applied to form the fuel cell30, a plurality of fuel cells30are laminated to form the fuel cell module40, and the sealing member80is disposed between the fuel cell modules40to form the laminate50; and a pressure application step, in which the laminate50is pressed from the lamination direction of the cells30by the pressure application unit10. In the first embodiment, an example is described in which the fuel cell module40is configured from two fuel cells30and the laminate50is configured from two fuel cell modules40; however, the above is only one example, and the invention is not limited thereto.

When manufacturing the module (step ST10inFIG. 1B), in the sealing member layout step, first, the MEA31or the separators32a,32bthat configure the fuel cell module30are set on the receiving jig12in the assembly device200, as illustrated inFIG. 2; the sealing member70is disposed on the separator32avia a coating on the upper surface of the placed member (step ST11inFIG. 1(C)). In the first embodiment, an anode separator32ais placed thereon as one example.

Next, the MEA31on which the sealing member70is disposed by the coating unit20is set on the separator32a, and a cathode separator32bon which the sealing member70is disposed is set on the MEA31(step ST12inFIG. 1(C)). The fuel cell30is thereby formed. When one more fuel cell30is formed in the same way, the parts that configure the fuel cell module40are stacked.

In this state, structures, such as the pressing jig11, the elastic member13, the detection unit14, the retaining unit15, and the pressing member16, are disposed, and the pressing load is applied (step ST13inFIG. 1(C)). The applied load is adjusted unless the applied load is within ±10% of the target value F (step ST14inFIG. 1(C): NO). If the applied load is within F±10% (step ST14inFIG. 1(C): YES), the nut18is fastened on the connecting bolt17to fix the thickness of the fuel cell module40to cure the sealing member70(step ST15inFIG. 1(C)). The value off 10% is an example, and this may be set to be another value. The fuel cell module40is completed with the step described above. When completed, the fuel cell module40is removed from the assembly device200.

In the next step, a leak test and an insulation and resistance test are performed (step ST20inFIG. 1B) in order to check if the module has any problems. If there is a problem in the test (step ST20inFIG. 1B: NO), the manufacturing of the module is performed again (step ST10inFIG. 1B). If there is no problem (step ST20inFIG. 1B: YES), the operation proceeds to the manufacturing of the laminate (stack)50. In the manufacturing of the laminate, the end plate36, the insulating plate35, the collector plate34, and the fuel cell module40are set on the pillars131,132of the assembly device300, and a plate member81, on both sides of which is applied the sealing member80, is stacked on the fuel cell module40. In the present embodiment, two fuel cells30are laminated, and two fuel cell modules40are prepared.

When two fuel cell modules40are stacked, the collector plate34, the insulating plate35, and the end plate36are set thereon. Then, the tension plates39a,39band the tension guides39c,39d, which configure the chassis, are attached and fastened with the bolt43(step ST30inFIG. 1B). Then, a leak test and a checking of the power generation performance as a laminate50are performed; if there is a problem (step ST40inFIG. 1B: NO), the load application on the laminate, etc., are performed again (step ST30inFIG. 1B). If there is no problem in the performance of the laminate50(step ST40inFIG. 1B: YES), the laminate is shipped.

The load when curing the sealing member that is applied to the fuel cell module will be described here.FIG. 16is an explanatory view illustrating the relationship between the load that is applied to the laminate and the thickness of the laminate in the lamination direction. As can be seen fromFIG. 16, the thickness of the laminate50decreases as the load that is applied to the laminate50increases.

In addition, as described above, since power generation is performed in the central portion41, the sealing member70cannot be applied to the central portion41, and the sealing member70is applied only to the outer peripheral part42.

Since the application site of the sealing member70is limited to the outer peripheral part42in this way, when the pressure from the pressing jig11is released, a phenomenon occurs in which a difference in the thicknesses is generated, such as the thickness of the central portion41of the fuel cell module40being H1and the thickness of the outer peripheral part42being H2, as illustrated inFIG. 13-FIG. 15. In view of such a phenomenon, the load that is applied when curing the sealing member70by pressing the laminate50(hereinafter referred to as the curing load of the sealing member70) must be equal to or less than the clamping pressure load when, for example, mounting the end plate36to the laminate50and clamping from both sides.

When the curing load of the sealing member70is greater than the clamping pressure load from the end plate36(when a1inFIG. 16is the curing load of the sealing member70and a2is the clamping pressure (mounting) load when stacking), the central portion41cannot be crushed to the thickness of the outer peripheral part, to which is coated the sealing member70when stacking; additionally, the difference between the thickness of the central portion41(b1inFIG. 12) and the thickness of the outer peripheral part42(b2inFIG. 12) cannot be eliminated.

By making the curing load of the sealing member70equal to or less than the clamping pressure load from the end plate36, the outer peripheral part42being excessively crushed is prevented, a difference occurring between the central portion41and the outer peripheral part42is prevented when stacking, and reliably forming the seal region becomes possible.

In addition, the curing load of the sealing member70may be configured to be equal to or less than the minimum load in an environment in which the fuel cell stack100is used (at the time of non-power generation); in addition, this load may be equal to or less than the clamping pressure load from the end plate36. When using the fuel cell stack100, fuel, the oxidizing agent, and cooling water are supplied inside the fuel cell stack100; as a result, the fuel cell stack100expands more than when mounting and clamping the end plate36. That is, the minimum load in an environment in which the fuel cell stack100is used will be smaller than the load when clamping, as described above. The seal member70must form a seal region in an environment in which the fuel cell stack100is used; therefore, even if the curing load of the sealing member70is configured to be equal to or less than the minimum load in the use environment, a seal region can be reliably formed by preventing the occurrence of a difference between the thicknesses of the central portion41and the outer peripheral part42in the module40.

Furthermore, besides the above, the curing load of the sealing member70may be configured to be equal to or less than the minimum load at which the separators32a,32bcome in contact with the MEA31, in the power generation portion41. In order for the fuel cell stack100to generate power, at least the separators32a,32bmust be put in contact with the MEA31so that space for the fuel and the oxidizing agent to flow is formed on both sides of the MEA31by the separators32a,32b. The minimum load with which the separators32a,32bcome in contact with the MEA31is equal to or less than the clamping pressure load described above and is equal to or less than the minimum load in an environment in which the fuel cell stack is used; however, this can cause the fuel cell stack to generate power. Accordingly, securing the power generation of the fuel cell stack and reliably forming the seal region are also possible by configuring the curing load of the sealing member70to be equal to or less than the minimum load at which the separators32a,32bcome in contact with the MEA31.

The action and effect of the invention according to the first embodiment will be described next.

When disposing the sealing members70,80on the laminate50, in order to seal the fuel, the oxidizing agent, etc., the sealing members70,80are disposed on the outer peripheral part42since disposing them on the central portion41, which is the power generation portion, is not possible. A seal region is not formed if the sealing members70,80(especially the sealing member80) are not sufficiently crushed, and the sealing member is not sufficiently crushed if there is a difference between the thicknesses of the central portion41and the outer peripheral part42. Accordingly, when assembling the fuel cell stack100by laminating the fuel cells30, the difference in the thicknesses between the central portion41and the outer peripheral part42must be eliminated so that a seal region is formed. However, for example, even if the gap between the MEA31and the separators32a,32is adjusted using a spacer or the like, there are cases in which the difference in the thicknesses between the central portion41and the outer peripheral part42cannot be eliminated due to variability.

In contrast, the first embodiment is configured to control the thickness of the laminate50by controlling, not the thickness of the laminate50, but the pressing load for pressing the laminate50, when pressing the laminate50with the pressure application unit10. Accordingly, in the first embodiment, variation in the thickness of the laminate50, etc. when assembling the fuel cell stack100can be considered, the laminate50can be pressed so that a difference in the thicknesses between the central portion41and the outer peripheral part42is not generated, and the sealing property can be improved by securing the compression amount of the sealing member.

In addition, the pressing load, when curing the sealing member70by pressing the laminate50in the pressure application step, is configured to be equal to or less than the clamping pressure load for clamping the laminate50with the load application member310and the pressing member320, when assembling the fuel cell stack100. Accordingly, if the laminate50is clamped from both ends by the end plate36when forming the fuel cell stack100, the central portion41can be crushed to the thickness of the outer peripheral part42, and a seal region can be reliably formed by making the thickness of the laminate50uniform.

In addition, the pressing load, when curing the sealing member70by pressing the laminate50in the pressure application step, may be configured to be equal to or less than the minimum load in an environment in which the fuel cell stack100is used (at the time of non-power generation). Since the minimum load in the use environment is equal to or less than the clamping pressure load from the end plate36, the central portion41can be crushed to the thickness of the outer peripheral part42at the time of assembling the fuel cell stack and in an environment in which the fuel cell stack is used in the same way as described above; as a result, reliably forming the seal member becomes possible.

In addition, the pressing load, when curing the sealing member70by pressing the laminate50in the pressure application step, may be configured to be equal to or less than the minimum load at which the separators32a,32bcome in contact with the MEA31. The minimum load at which the separators32a,32bcome in contact with the MEA31is equal to or less than the load at the time of clamping by the end plate36and in an environment in which the fuel cell stack is used. Accordingly, by configuring the above-described pressing load to be equal to or less than the minimum load at which the separators32a,32bcome in contact with the MEA31, securing the power generation of the fuel cell stack100while reliably forming the seal region by crushing the central portion41to the thickness of the outer peripheral part42is possible, even when assembling the fuel cell stack and in an environment in which the fuel cell stack100is used.

In addition, the embodiment is configured so that, when applying the pressing load with the pressing jig11, the pressing load is monitored by a detection unit14consisting of a load cell, etc., and so that a state in which the laminate50is pressed is retained by the retaining unit15. Accordingly, an excessive pressing load being applied to the laminate50can be reliably prevented, a difference occurring between the central portion41and the outer peripheral part42is prevented, and reliably forming the seal region becomes possible.

Additionally, if a state is maintained in which the laminate50is pressed along with the retaining unit15, using an elastic member13comprising a plate spring13a, etc., for the pressing jig11, the load fluctuation can be released even when a load fluctuation to the laminate50is generated due to a temperature change when curing the sealing member70. Therefore, scratches, etc. being generated due to an occurrence of a concentration of stress on the laminate50can be prevented.

In addition, the uneven, so-called corrugated shape32c, which is formed on the separators32a,32b, may function as an elastic member, such as a plate spring. Accordingly, damage to the laminate50is prevented by preventing stress from concentrating at the boundary of the central portion41and the outer peripheral part42even when applying the pressing load for curing the sealing member70; as a result, managing of the thickness of the laminate50via the pressing load becomes possible.

Second Embodiment

FIG. 18is a cross-sectional view illustrating the jig structure in the laminate assembly device according to the second embodiment. In the first embodiment, the laminate50was pressed by a single jig, the pressing jig11, but the invention may also be configured as follows.

In the fuel cell stack assembly device200aof the second embodiment, the pressing jig is configured from a pressing jig11athat presses the central portion41, corresponding to the power generation portion in the laminate50, and an annular pressing jig11bthat presses an outer portion42that is outward of the central portion41, as illustrated inFIG. 18. The load that is applied by the pressing jig11aand the load that is applied by the pressing jig11bmay be made different loads by adjusting the spring constant of the elastic member13band the elastic member13c, which are connected to the pressing member16. The other configurations of the assembly device200aare the same as those in the first embodiment, aside from the detection units14a,14bfor respectively detecting the pressing weight of the pressing jigs11a,11b; therefore, the descriptions thereof are omitted.

The assembly device200aof the laminate50according to the second embodiment is configured so that the loads that are applied to the central portion41and the outer portion42in the laminate50are applied separately. Accordingly, even if the variation in the thickness dimension in the planar direction of the laminate50is greater, the difference in the thicknesses of the central portion41and the outer peripheral part42is more easily eliminated by being able to separately press the central portion41and the outer peripheral part42; as a result, reliably forming the seal region becomes possible.

Third Embodiment

FIG. 19is an explanatory view illustrating the jig structure in the laminate assembly device according to the third embodiment. In the first embodiment, a pressing jig11in which the pressing surface that presses the laminate50is flat was used to press the laminate50and to cure the sealing member70; however, the pressing jig may also be configured as follows.

The pressing jig11cthat configures the assembly device200bof the fuel cell module in the third embodiment has a pressing surface for pressing the laminate50that is not flat and comprises a power generation portion pressing portion11dfor pressing the central portion41, corresponding to the power generation portion, and an outer pressing portion11efor pressing the outer side of the power generation portion pressing portion11d. Since use in cold regions must be guaranteed for automobiles equipped with the fuel cell stack100, forming a seal region with the sealing member70must be considered for the laminate50even when cold. In contrast, in the assembly device200bof the laminate50according to the third embodiment, the pressing jig31cis configured so that the power generation portion pressing portion11dcomprises a step11fin the lamination direction, with respect to the outer portion pressing portion11e. The height of the step11finFIG. 17may be the heat-shrinkage amount of the sealing member70within a guaranteed temperature; however, this is not limited thereto.

By providing a step11fto the pressing jig11cwith consideration for shrinkage or the like due to the temperature change of the sealing member70, a difference occurring between the central portion41and the outer peripheral part42is prevented even when the shrinkage amount is different between the central portion41and the outer peripheral part42in the laminate50; as a result, reliably forming the seal region becomes possible.

The present invention is not limited to the embodiment described above, and various modifications are possible within the scope of the claims.

FIGS. 20, 21are explanatory views illustrating a modified example of a jig structure in the laminate assembly device according to the third embodiment. In the third embodiment, the description explained that the seal region is allowed to be formed even when the sealing member70undergoes heat shrinkage by providing a step11fto the pressing jig11c; however, the invention is not limited thereto. In the pressing jig11gto which is provided a step, the corner of the power generation portion pressing portion11d, which presses the central portion41, may be formed in a curved shape11h. By forming the corner of the power generation portion pressing portion11din a curved shape11h, the contact surface pressure between the laminate50and the curved shape11hwill not be excessive even when pressing them; as a result, a seal region can be formed without an occurrence of scratches and the like on the laminate50.

In addition, step11f, which is provided in consideration of heat shrinkage or the like caused by the temperature change of the sealing member70, may be provided not only to the pressing jig but also to the receiving jig, as illustrated inFIG. 21. In addition, in the first to the third embodiments, a plurality of fuel cells were laminated to form the fuel cell module, and a plurality of fuel cell modules were laminated to configure the laminate; however, the invention is not limited thereto; the present invention may also be applied to a case in which a seal region is formed by disposing the sealing member70on a single fuel cell module in which a plurality of fuel cells are laminated.

In addition, of the spaces between the MEA31and the separators32a,32b, which configure the fuel cell module40, a corrugated shape32cof the separators32a,32band a gas diffusion layer that configures the MEA31are present in the portion of the central portion41; however, such a configuration does not exist in the portion of the outer peripheral part42. Consequently, there are cases in which the collapsing degree when a load is applied will vary between the lateral direction of the outer peripheral part42, which is relatively far from the central portion41, and the longitudinal direction, which is relatively near the central portion41of the outer peripheral part42when curing the sealing member, etc., by pressing the fuel cell module40, which may have impact the sealing property. With respect to this, the difference in the collapsing degree between the longitudinal direction and the lateral direction of the outer peripheral part42may be eliminated by providing a hole to a part of the jig11in a region that is in contact with the lateral direction of the jig11inFIG. 4and that connects to a pump. By providing such a configuration, the difference in the collapsing amount between the central portion41and the outer peripheral part42when curing the sealing member can be eliminated or reduced.