Manufacturing apparatus for use with a membrane electrode assembly and method for manufacturing same

Disclosed herein is a membrane electrode assembly with a superior power generating efficiency and a method of manufacturing the same. Also disclosed is a manufacturing apparatus thereof wherein a gasket with an optimum thickness can be easily applied to the membrane electrode assembly without preparing various types of gaskets. A method of manufacturing the membrane electrode assembly with catalytic layers and gas diffusion layers on surfaces of the electrolyte membrane comprises controlling a molding thickness according to thicknesses of the catalytic layers and the gas diffusion layers and integrally molding the gasket portions formed with resin materials on at least one surface of the electrolyte membrane.

CROSS REFERENCE RELATED TO APPLICATIONS

This application claims priority to Japanese Patent Application Serial No. 2007-070874, filed Mar. 19, 2007 and Japanese Patent Application Serial No. 2007-304692, filed Nov. 26, 2007, each of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The invention relates to a membrane electrode assembly and a method of manufacturing the same. The invention also relates to a manufacturing apparatus thereof.

BACKGROUND

Generally, a fuel cell is formed by stacking a membrane electrode assembly that forms a catalytic layer and a gas diffusion layer on each of the surfaces of an electrolyte membrane and interposing a separator therebetween. WO 01/017048 discloses an electrolyte membrane exposed to the catalytic layer. The gas diffusion layer is not formed at an outer peripheral portion of the membrane electrode assembly. Further, a gasket formed with a resin material for providing sealing between the outer peripheral portion and the separator is applied thereto. An optimum thickness of such a gasket is determined based on a thickness of the gas diffusion layer. Thus, when there is a change in size of the gas diffusion layer, it is necessary to prepare various types of gaskets with different thicknesses to accommodate the changing thickness of the gas diffusion layer. However, gaskets of varying thicknesses are limited, and it is possible that a gasket having the optimum thickness for a gas diffusion layer cannot be used. For example, when the gasket is not thick enough, the gas diffusing performance and the drainage performance deteriorate since the gas diffusion layer is excessively pressed and crushed. Alternatively, when the gasket is too thick, the power generating efficiency deteriorates since the electrical resistance of the gas diffusion layer increases.

BRIEF SUMMARY

Disclosed herein are methods of manufacturing a membrane electrode assembly wherein the membrane electrode assembly has both a catalytic layer and a gas diffusion layer on opposing surfaces of an electrolyte membrane. One such method comprises measuring thicknesses of the catalytic layer and the gas diffusion layer, determining a thickness of a gasket portion according to the thicknesses of the catalytic layer and the gas diffusion layer and molding the gasket portion having the determined thickness around the catalytic layer and the gas diffusion layer on the electrolyte membrane.

Also disclosed are embodiments of a manufacturing apparatus to be used with a membrane electrode assembly. One embodiment of the manufacturing apparatus comprises a mold cast including a gripping portion configured to grip an edge portion of the catalytic and the gas diffusion layers, a measuring portion configured to measure thicknesses of the catalytic layer and the gas diffusion layer, a moveable block operable to move forward and backward against the electrolyte membrane along an inner side surface of the gripping portion, the moveable block having a side opposite the gripping portion and adjacent to an outer peripheral end of the gas diffusion layer, and a control portion configured to control the forward-backward movement of the moveable block according to the thicknesses of the catalytic layer and the gas diffusion layer.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown inFIGS. 1 and 2, a membrane electrode assembly1in accordance with a first embodiment has a stacking structure wherein a solid polymer electrolyte membrane2is inserted between an anode3and a cathode4. The solid polymer electrolyte membrane2may include a perfluorocarbon polymer membrane having a sulfonic acid base. An example of this is Nafion 1128®. The anode3comprises a first catalytic layer5A and a first gas diffusion layer6A, while the cathode4comprises a second catalytic layer5B and a second gas diffusion layer6B. At the edges of the membrane electrode assembly1, a first gasket portion8A and a second gasket portion8B formed with resin materials are integrally installed on each side of the electrolyte membrane2and around the edges of the catalytic layers5A and5B and the gas diffusion layers6A and6B. Thicknesses H1and H2of the first and second gasket portions8A and8B, respectively, are formed such that the surfaces of gasket portions8A and8B opposite the electrolyte membrane2do not extend as high as the surfaces of the first and second gas diffusion layers6A and6B. The first and second gas diffusion layers6A and6B extend higher than the first and second gasket portions8A and8B by step heights H3and H4, respectively. Outer peripheral edge portions of the gasket portions8A and8B are inclined to form inclined surfaces10A and10B.

As shown inFIG. 3, the membrane electrode assembly1overlaps with a separator9when constituting a fuel cell. At this time, the gasket portions8A and8bare adhered to the separator9, thereby functioning to prevent leakage of fuel gas or coolant. Since the gas diffusion layers6A and6B are formed higher than the gasket portions8A and8B, they are compressed until their surfaces are planar with the surfaces of the gasket portions8A and8B. If the gas diffusion layers6A and6B are excessively pressed and crushed, then the gas diffusing performance and the drainage performance deteriorate. Further, if the gas diffusion layers6A and6B are not compressed enough, then the electrical resistance increases. Thus, it is desirable that the thicknesses H1and H2of the gasket portions8A and8B are manufactured to optimize the gas diffusing performance, the drainage performance and the electrical resistance. In the present embodiment, the thicknesses H1and H2of the gasket portions8A and8B are established such that the step heights H3and H4become, for example, predetermined values within a range of 30 to 200 μm. However, the invention is not specifically limited to values within such a range.

The manufacturing apparatus of the membrane electrode assembly in accordance with the first embodiment comprises an apparatus for installing a pre-assembly21as illustrated inFIGS. 4 and 5, which forms the catalytic layers5A and5B and the gas diffusion layers6A and6B on both surfaces of the electrolyte membrane2. The apparatus also integrally injection-molds or injection thermal compression-molds the gasket portions8A and8B by injecting the resin materials to the electrolyte membrane2. The pre-assembly21has a plurality of through-holes22along the edge portion of the electrolyte membrane2.

As shown inFIGS. 6 to 9, the manufacturing apparatus20of the membrane electrode assembly comprises a pair of first and second mold casts25A and25B, respectively including a first moveable block24A and a second moveable block24B therein. The manufacturing apparatus20further comprises a pressing device (not shown) for pressing the first and second mold casts25A and25B, a first driving portion26A and a second driving portion26B for driving the first and second moveable blocks24A and24B, a first control portion28A and a second control portion28B (shown inFIG. 9) for controlling the first and second driving portions26A and26B, a first measuring portion29A for measuring a total thickness of the first catalytic layer5A and the first gas diffusion layer6A, and a second measuring portion29B for measuring a total thickness of the second catalytic layer5B and the second gas diffusion layer6B. The first and second measuring portions29A and29B are arranged on the first and second mold casts25A and25B, respectively.

Referring toFIG. 9, the first mold cast25A and the second mold cast25B can be relatively closely spaced by the pressing device. A first gripping portion31A and a second gripping portion31B for inserting and gripping the edge portion of the electrolyte membrane2are formed on outer peripheries of each opposite surface of the first and second mold casts25A,25B. A plurality of projections32are formed on a surface of the second gripping portion31B opposite to the first gripping portion31A in a circumferential direction, while a fitting portion33is formed on a surface of the first gripping portion31A opposite to the second gripping portion31B. The projections32are matingly received by the fitting portions33. Since inner side corner portions of the first and second gripping portions31A and31B are inclined against a surface of fitting and supporting the electrolyte membrane2, gripping portion inclined surfaces35A and35B are formed. Also, one or more gates36A and36B for injecting the resin materials are installed on the gripping portion inclined surfaces35A and35B.

The gates36A and36B are formed of a pin gate or a film gate having a width in a shape of a film. The gates36A and36B are in communication with supply pipes37A and37B connected to the mold casts25A and25B from the outside. The resin materials are supplied from the supply pipes37A and37B.

In each opposite surface of the first mold cast25A and the second mold cast25B, a first block receiving portion39A and a second block receiving portion39B, each in a shape of a recessed groove, are formed along the inner side surfaces of the gripping portions31A and31B. The first moveable block24A is received in the first block receiving portion39A, while the second moveable block24B is received in the second block receiving portion39B. As shown inFIGS. 7 and 8, corresponding to the shapes of the first block receiving portion39A and the second block receiving portion39B, the first moveable block24A and the second moveable block24B are installed by being divided into four blocks in a circumferential direction. However, the four blocks are provided as a non-limiting example, and the number of divisions is not limited. Further, the blocks need not be divided.

The first moveable block24A is configured to be forwardly and backwardly moveable toward a direction of the installed pre-assembly21by the first driving portion26A having a servo motor, cylinder, or the like. Further, the second moveable block24B is also configured to be forwardly and backwardly moveable toward a direction of the installed pre-assembly21by the second driving portion26B having a servo motor, cylinder, or the like. In the first moveable portion24A and the second moveable portion24B, a first opposite surface and a second opposite surface opposed to the pre-assembly21are formed. Opposite surface inner side portions41A and41B in opposite side (inner side) of the gripping portions31A and31B of each opposite surface are positioned opposite to outer peripheral ends of the gas diffusion layers6A and6B. The forward and backward movements of the first and second moveable blocks24A and24B are controlled by the first and second control portions28A and28B, respectively.

The first control portion28A and the second control portion28B are generally implemented by software stored on, for example, memory of a computer and operated by a central processing unit (CPU).

In the first mold cast25A, one or more first measuring portions29A for measuring the thickness of the first catalytic layer5A and the first gas diffusion layer6A are installed at a position opposite to the first gas diffusion layer6A of the pre-assembly21. The first measuring portion29A is, for example, a pressure gauge wherein the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A are converted from a pressure when contacting the first gas diffusion layer6A with a predetermined protruding amount. Further, the first measuring portion29A, for example, may include a displacement gauge. Each first measuring portion29A is connected to the first control portion28A, and a measuring signal from the first measuring portion29A is input to the first control portion28A. The first control portion28A calculates an average of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A based on signals from a plurality of the first measuring portions29A. According to the result of such a measurement, the first moveable block24A can be forwardly and backwardly moved.

Similarly, in the second mold cast25B, one or more second measuring portions29B for measuring the thickness of the second catalytic layer5B and the second gas diffusion layer6B are installed at a position opposite to the second gas diffusion layer6B of the pre-assembly21. The second measuring portion29B is, for example, a pressure gauge wherein the thicknesses of the second catalytic layer5B and the second gas diffusion layer6B are converted from a pressure when contacting the second gas diffusion layer6B with a predetermined protruding amount. Further, the second measuring portion29B, for example, may include a displacement gauge. Each second measuring portion29B is connected to the second control portion28B, and a measuring signal from the second measuring portion29B is input to the second control portion28B. The second control portion28B calculates an average of the thicknesses of the second catalytic layer5B and the second gas diffusion layer6B based on signals from a plurality of the second measuring portions29B. According to a result of such a measurement, the second moveable block24B can be forwardly and backwardly moved.

Next, a manufacturing method of the membrane electrode assembly1in accordance with the first embodiment is explained.

First, as shown inFIG. 10, the pre-assembly21is installed in the second mold cast25B. At this time, the projection32of the second mold cast25B is inserted through the through hole22of the pre-assembly21. As a result, the pre-assembly21can be securely retained and supported at the time of the injection molding operation.

Thereafter, as shown inFIG. 11, the first mold cast25A and the second mold cast25B are closed by the pressing device, thereby being mold-clamped. By doing so, the electrolyte membrane2of the pre-assembly21is inserted and gripped between the first gripping portion31A and the second gripping portion31B. The projection32of the second gripping portion31B is fitted into the fitting portion33of the first gripping portion31A. Further, as the first moveable block24A and the second moveable block24B approach each other, the opposite surface inner side portions41A and41B press the first and second gas diffusion layers6A and6B. Consequently, a first injection space42A and a second injection space42B are formed on an outer side of the gas diffusion layers6A and6B and the catalytic layers5A and5B of the electrolyte membrane2.

Next, based on the pressure value from the plurality of the first measuring portions29A sent to the first control portion28A, an average of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A is calculated. Then, the first moveable block24A is forwardly and backwardly moved by controlling the first driving portion26A by a predetermined amount according to such a calculated result. Here, it is desirable that the pressure value measured by the first measuring portion29A and the average of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A are stored and calculated by previously measuring a relationship between the pressure value and the thickness by an experiment. Further, instead of measuring the pressure value, the measurement can be performed by using a displacement gauge or laser measuring instrument. However, at this time, it is not necessary to convert the thickness from the pressure by a previous experiment. As described above, since known techniques can be appropriately applied to measure the thickness, the details thereof are omitted herein.

Similar to the above, based on the signal input from the plurality of the second measuring portions29B to the second control portion28B, an average of the thicknesses of the second catalytic layer5B and the second gas diffusion layer6B is calculated. Then, the second moveable block24B is forwardly and backwardly moved by controlling the second driving portion26B by a predetermined amount according to such a calculated result. The thicknesses of the catalytic layers5A and5B are very thin, being within a range of 3 to 20 μm, and variation thereof is very small. In contrast, the thicknesses of the gas diffusion layers6A and6B are comparatively thick, being within a range of 200 to 600 μm, and variation thereof is large. As such, it is also possible to form the pre-assembly21by previously measuring only the thicknesses of the gas diffusion layers6A and6B and attaching them to the solid polymer electrolyte membrane2and simply adding the approximate thicknesses of the catalytic layers (about 3 to 20 μm or 0 since the value is extremely small). However, operating performance may be deteriorated as this is not as accurate as the present embodiment.

Thereafter, as shown inFIG. 12, the resin materials are injected from the supply pipes37A and37B through the gates36A and36B to the first injection space42A and the second injection space42B.

When the resin material is a thermoplastic resin, the membrane electrode assembly1is extracted wherein the first gasket portion5A and the second gasket portion8B are molded by releasing the first mold cast25A and the second mold cast25B after the resin material is injected in a fused state and the resin material is hardened due to a drop in temperature.

When the resin material is a thermosetting resin, the membrane electrode assembly1is extracted wherein the first gasket portion8A and the second gasket portion8B are molded by releasing the first mold cast25A and the second mold cast25B after the resin material in a liquid phase is injected. The resin material is then hardened by heating at a temperature higher than a hardening temperature by a heater (not shown) installed in the first mold cast25A and the second mold cast25B.

According to the membrane electrode assembly1manufactured as above, since the resin material is injected from the inclined surfaces10A and10B, resin remaining in the gates36A and36B and protruding in an outer peripheral direction after the gates are removed can be prevented from contacting the separator9. Further, adhesion with the separator9can be favorably maintained when constituting the fuel cell.

According to the thicknesses of the catalytic layer5A and the gas diffusion layer6A, as well as the catalytic layer5B and the gas diffusion layer6B, since each moveable block24A and25B is moved, the catalytic layers5A and5B and the gasket portions8A and8B can be molded to have optimum thicknesses corresponding to the gas diffusion layers6A and6B.

Such an optimum thickness is, for example, established such that the thicknesses H1and H2of the gaskets are respectively determined as 80% of the thicknesses of the catalytic layer5A and the gas diffusion layer6A and the thicknesses of the catalytic layer5B and the gas diffusion layer6B. Further, such a ratio can be appropriately varied according to the types of the gas diffusion layers.

Also, at the time of the injection-molding operation, since the moveable blocks24A and24B are contacted while compressing the gas diffusion layers6A and6B, the resin materials can be restrained from penetrating into the gas diffusion layers6A and6B. Moreover, the deterioration of the gas diffusing performance of the gas diffusion layers6A and6B and the drainage performance can be restrained.

Further, the thicknesses H1and H2of the gasket portions8A and8B can be established by measuring the thicknesses of the catalytic layer5A and the gas diffusion layer6A, as well as the catalytic layer5B and the gas diffusion layer6B, by the measuring portions29A and29B, even when the thicknesses of the gas diffusion layers6A and6B are changed. Thus, it is possible to maintain the step heights H3and H4with the optimum value. In addition, the deterioration of the power generating efficiency of the fuel cell can be suppressed by restraining the deterioration of the gas diffusing performance and the drainage performance of the gas diffusion layers6A and6B.

Because the step heights H3and H4can be established separately, even when the materials of an anode side and a cathode side of the gas diffusion layers6A and6B are different, each side can be maintained with the optimum step heights H3and H4.

The gasket portions8A and8B can be integrally molded with an optimum size, making it unnecessary to have various types of gaskets prepared, thereby reducing costs.

According to the membrane electrode assembly1of this embodiment, since the gasket portions8A and8B are integrally molded, the number of components can be reduced, and position precision can be improved. Further, when the gasket is installed as a separate member, there may be a concern that bubbles or impurities are intermixed between the gasket and the electrolyte membrane. However, according to the manufacturing method disclosed herein, the likelihood of intermixing a bubble or impurities is very low. Because it is not necessary to bond the gasket as a separate member when assembling the fuel cell, the number of operations can be reduced.

A manufacturing apparatus50of a membrane electrode assembly and a manufacturing method in accordance with a second embodiment differ from the manufacturing apparatus20and the manufacturing method in accordance with the first embodiment. Specifically, the gasket portions8A and8B are compression-molded in the second embodiment, whereas the gasket portions8A and8B are injection-molded or injection thermal compression-molded in the first embodiment. Further, the membrane electrode assembly1manufactured in the second embodiment has the same structure of the membrane electrode assembly1in the first embodiment.

As to the portions having the same functions as in the first embodiment, same reference numerals are denoted and explanations thereof are omitted in order to avoid repetition.

The manufacturing apparatus50of the membrane electrode assembly in accordance with the second embodiment comprises an apparatus for installing the pre-assembly21as inFIGS. 4 and 5, which forms the catalytic layers5A and5B and the gas diffusion layers6A and6B on both surfaces of the electrolyte membrane2. The apparatus also integrally compression-molds the gasket portions8A and8B on the electrolyte membrane2.

As shown inFIG. 13, the manufacturing apparatus50comprises a pair of a first mold cast52A and a second mold cast52B, respectively including a first moveable block51A and a second moveable block51B therein.

The first moveable block51A comprises a first heating portion53, which is used to heat the first moveable block51A. The first heating portion53has is elongated along a length direction of the first moveable block51A. A heat transfer heater unit is preferable used for the first heating portion53in the present embodiment, although other structures (e.g., a structure of using a high frequency heater or leaking a high temperature fluid) may be applied. Further, since the heat transfer heater unit is a known device, the detailed explanations thereof is omitted herein. The first heating portion53is connected to an external power source unit (not shown), and a temperature of the first heating portion53can be arbitrarily established by controlling the power source unit.

The second moveable block51B comprises a second heating portion54for heating the second moveable block51B and a block cooling portion55for cooling the second moveable block51B. The second heating portion54is elongated along a length direction of the second moveable block51B. A high frequency heater unit capable of rapid heating is preferable as the second heating portion54in the present embodiment although other structures (e.g., a structure of using a heat transfer heater or leaking a high temperature fluid) may be applied. Further, since the high frequency heater unit is a known device, the detailed explanations thereof are omitted herein. The second heating portion54is connected to an external power source unit (not shown), and a temperature of the second heating portion54can be arbitrarily established by controlling the power source unit.

The block cooling portion55is elongated along a length direction of the second moveable block51B. A Peltier system cooling element is preferable for the block cooling portion55in the present embodiment, although other structures (e.g., a structure of leaking a low temperature fluid) may be applied. The block cooling portion55is connected to an external power source unit (not shown), and a temperature of the block cooling portion55can be arbitrarily established by controlling the power source unit.

In a first center portion56A of the first mold cast52A surrounded by the first moveable block51A, a first mold cast cooling portion57A is installed. Further, in a second center portion56B of the second mold cast52B surrounded by the second moveable block52B, a second mold cast cooling portion57B is installed.

The first mold cast cooling portion57A and the second mold cast cooling portion57B comprise a first cooling flow path58A and a second cooling flow path58B, respectively. A cooling medium (e.g., coolant water) can be supplied from an external cooling fluid supply source (not shown) via cooling fluid supply pipes59A and59B to the first cooling flow path58A and the second cooling flow path58B. The first cooling flow path58A is formed as a plurality of flow paths along a length direction of each first moveable block51A so as to surround four sides of the first center portion56A. The second cooling flow path58B is also formed as a plurality of flow paths along a length direction of each second moveable block51B so as to surround four sides of the second center portion56B. Shapes of the flow paths are not specifically limited but may include a formation of a single path rather than a plurality of paths bent in a rectangular shape along length directions of the first and second moveable block51A and51B.

Next, a manufacturing method of the membrane electrode assembly in accordance with the second embodiment is explained.

First, the first center portion56A and the second center portion56B of the first mold cast52A and the second mold cast52B are cooled by supplying the cooling medium from the cooling fluid supply source to the first and second cooling flow paths58A and58B. Simultaneously, the first moveable block51A is heated by operating the first heating portion53. Heating of the first moveable block51A while cooling the first center portion56A and the second center portion5613is maintained all the time during a processing cycle.

Then, the second moveable block51B is cooled by operating the block cooling portion55.

Next, as shown inFIG. 14, a second resin filling material60B is loaded on the second moveable block51B of the second mold cast52B. Then, the pre-assembly21is installed on the second mold cast52B. At this time, since the projection32of the second mold cast52B is inserted through the through-hole22of the pre-assembly21, the pre-assembly21can be securely retained and supported at the time of a compression-molding operation, which is explained below. Thereafter, as shown inFIG. 15, a first resin filling material60A is loaded on a position corresponding to the first moveable block51A of the pre-assembly21.

The first and second filling materials60A and60B described above are materials in the shape of a sheet mainly consisting of thermosetting resins. For example, such materials can be input in any position by suctioning with a suction pad in the shape of a sponge. Further, the first and second filling materials60A and60B may include a powder material, a semi-hardened material obtained by pre-heating the powder material or a gel material (i.e., slurry material). In the case of the powder or gel, the first and second filling materials60A and60B can be injected on any position by being discharged from a nozzle. Also, the first and second filling materials60A and60B are formed in an annular shape surrounding an outer periphery of the gas diffusion layers6A and61B, although the first and second filling materials60A and60B may be installed by being divided into a plurality of pieces.

Thereafter, as shown inFIG. 16, the first mold east52A and the second mold cast52B are closed by the pressing means to thereby become mold-clamped, while being rapidly heated by stopping operation of the block cooling portion55of the second moveable block51B and operating the second heating portion54. At this time, the electrolyte membrane2of the pre-assembly21is inserted and gripped between the first gripping portion31A and the second gripping portion31B. Further, the projection32of the second gripping portion31B is fitted in the fitting portion33of the first gripping portion31A. Also, the first moveable block51A and the second moveable block51B are pressed toward each other so that the opposite surface inner side portions41A and41B press the first and second gas diffusion layers6A and6B.

The first and second filling materials60A and60B are fused by the first moveable block51A and the second moveable block51B heated by the first heating portion53and the second heating portion54. While the first and second filling materials60A and60B are in a fused state, an average value of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A is calculated by a plurality of the first measuring portions29A. Based on a predetermined amount according to the calculated average value of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A, the first moveable block51A is forwardly and backwardly moved by controlling the first driving portion26A.

Likewise, while the first and second filling materials60A and60B are in a fused state, an average value of the thicknesses of the second catalytic layer5B and the second gas diffusion layer6B is calculated by a plurality of the second measuring portions29B. Based on a predetermined amount according to such a calculated result, the second moveable block51B is forwardly and backwardly moved by controlling the second driving portion26B.

Thereafter, until the first and second filling materials60A and GOB are hardened, the positions and heating temperatures of the first and second moveable blocks51A and51B are maintained. At a point of time when a hardening reaction is ended until the shapes of the first and second filling materials can be maintained despite being released, the first mold cast52A and the second mold cast52B are released. By doing so, the membrane electrode assembly1wherein the first gasket portion8A and the second gasket portion8B are molded is extracted.

Next, the heating is ended by stopping the operation of the second heating portion54. The second moveable block51B is cooled by operating the block cooling portion55. After a temperature of the second moveable block51B is decreased to a predetermined temperature, the manufacturing of the membrane electrode assembly1below is started.

As in the above manufacturing apparatus50and the manufacturing method in accordance with the second embodiment, despite using the compression-molding operation and not the injection-molding or injection thermal compression-molding operation, the gasket portions8A and8B can be molded to have an optimum thickness corresponding to the thicknesses of the catalytic layer5A and the gas diffusion layer6A, as well as the catalytic layer5B and the gas diffusion layer6B as in the first embodiment.

Further, as an effect differing from the first embodiment, since the first and second mold cast cooling portions57A and57B are installed in the first and second center portion56A and56B adjacent or adhered to the gas diffusion layers6A and6B of the pre-assembly21, a region of the pre-assembly21can be protected from an excessive temperature increase, as it is not required to be heated.

Moreover, since the second filling material60B is arranged under the pre-assembly21before the first mold cast52A and the second mold cast52B are mold-clamped, a downward suspension of the pre-assembly21is prevented by the second filling material60B. The pre-assembly21can be retained and supported at a more appropriate position.

Also, since the first and second heating portions53and54are installed in the first and second moveable blocks51A and51B, a region required to be heated can be intensively heated.

Further, since the block cooling portion55is installed in the second moveable block51B, the second moveable block51B wherein the second filling material60B is arranged can be intensively cooled. Thus, when the membrane electrode assembly1is sequentially manufactured, since the second moveable block51B can be cooled in a short time, the working hours can be reduced.

Also, the first and second mold cast cooling portions57A and57B, the first and second heating portions53and54and the block cooling portion55of the manufacturing apparatus50, which are in accordance with the second embodiment, are applicable to the first embodiment.

A manufacturing apparatus70of a membrane electrode assembly and a manufacturing method in accordance with a third embodiment differ from the manufacturing apparatuses20and50and manufacturing methods in accordance with the first and second embodiments since the gasket portion8A at one side is injection-molded or injection thermal compression-molded while the gasket portion8A at the other side is compression-molded. Further, the membrane electrode assembly1in the third embodiment has the same structure as the membrane electrode assembly1in the first and second embodiments. As to the portions having the same functions as in the first embodiment, same reference numerals are denoted, and the explanations thereof are omitted herein in order to avoid repetition.

The manufacturing apparatus70of the membrane electrode assembly in accordance with the third embodiment comprises an apparatus for installing the pre-assembly21as seen inFIGS. 4 and 5, which forms the catalytic layers5A and5B and the gas diffusion layers6A and6B on both surfaces of the electrolyte membrane2, and for injection molding or injection thermal compression-molding the gasket portion8A at one side and compression-molding the gasket portion8B at the other side of the electrolyte membrane2.

Such a manufacturing apparatus70of the membrane electrode assembly is the same as the manufacturing apparatus50in accordance with the second embodiment, except that a gate72is formed on a first mold cast71A, and a supply pipe73for supplying a resin material is connected to the gate72. Similar to the gate36A in the first embodiment, the gate72is formed of a pin gate or a film gate having a width in the shape of a film.

Next, a manufacturing method of the membrane electrode assembly in accordance with the third embodiment is explained below.

First, the first center portion56A and the second center portion56B of the first mold cast71A and the second mold cast71B are cooled by supplying the cooling medium from the cooling fluid supply source to the first and second cooling flow paths58A and5813. Simultaneously, the first moveable block51A is heated by operating the first heating portion53. Heating the first moveable block51A while cooling the first center portion56A and the second center portion56B are maintained all the time during a processing cycle. Then, the second moveable block51B is cooled by operating the block cooling portion55.

Next, as shown inFIG. 18, a second resin filling material74is loaded on the second moveable block51B of the second mold cast71B. Then, the pre-assembly21is installed on the second mold cast71B. At this time, since the projection32of the second mold cast71B is inserted through the through-hole22of the pre-assembly21, the pre-assembly21can be securely retained and supported at the time of a compression-molding operation, as explained below.

The second filling material74described above is a material in the shape of a sheet mainly consisting of thermosetting resins as in the second embodiment. For example, such a material can be injected in any position by suctioning with a suction pad in the shape of a sponge. Further, the second filling material74may include a powder material, a semi-hardened material obtained by pre-heating the powder material or a gel material (i.e., slurry material). In the case of the powder or gel, the second filling material74can be input at an arbitrary position by being discharged from a nozzle. Also, the second filling material74is formed in an annular shape surrounding an outer periphery of the gas diffusion layer6B, although the second filling material74may be installed by being divided into a plurality of pieces.

Thereafter, as shown inFIG. 19, the first mold cast71A and the second mold cast71B are closed by the pressing device to thereby become mold-clamped, while being rapidly heated by stopping operation of the block cooling portion55of the second moveable block51B and operating the second heating portion54. At this time, the electrolyte membrane2of the pre-assembly21is inserted and gripped between the first gripping portion31A and the second gripping portion31B. Further, the projection32of the second gripping portion31B is fitted in the fitting portion33of the first gripping portion31A. The first moveable block51A and the second moveable block51B are in contact so that the opposite surface inner side portions41A and41B press the first and second gas diffusion layers6A and6B. As a result, a first injection space75is formed at outer sides of the gas diffusion layer6A and the catalytic layer5A of the electrolyte membrane2.

The second filling material74is fused by the second moveable block51B heated by the second heating portion54. While the second filling material74is in a fused state, an average value of the thicknesses of the first catalytic layer5A and the first gas diffusion layer6A is calculated by a plurality of the first measuring portions29A. Based on a predetermined amount according to the calculated result, the first moveable block51A is forwardly and backwardly moved by controlling the first driving portion26A.

Likewise, while the first and second filling materials60A and60B are in a fused state, an average value of the thicknesses of the second catalytic layer5B and the second gas diffusion layer6B is calculated by a plurality of the second measuring portions29B. Based on a predetermined amount according to such a calculated result, the second moveable block51B is forwardly and backwardly moved by controlling the second driving portion26B.

Thereafter, as shown inFIG. 20, the resin material is injected from the supply pipe73through the gate72to the first injection space75. Also, it is desirable if the same material as the second filling material74is used for the resin material, although the invention is not limited to such a configuration.

Until the second filling material74and the injected resin material are hardened, the positions and temperatures of the first and second moveable blocks51A and51B are maintained. Also, when a hardening reaction is ended, meaning the shapes of the second filling material74and the resin material can be maintained despite being released, the first mold cast71A and the second mold cast71B are released. By doing so, the membrane electrode assembly1with the molded first gasket portion8A and the second gasket portion8B is extracted. Thereafter, the heating is ended by stopping the operation of the second heating portion54.

Then, the second moveable block51B is cooled by operating the block cooling portion55. After a temperature of the second moveable block51B is decreased to a predetermined temperature, the manufacturing of the membrane electrode assembly1is started.

As in the above manufacturing apparatus70and the manufacturing method in accordance with the third embodiment, even when using a mixture of the compression-molding operation with the injection molding operation or the injection thermal compression-molding operation, the gasket portions8A and8B can be molded to have an optimum thickness corresponding to the thicknesses of the catalytic layer5A and the gas diffusion layer6A, as well as the catalytic layer5and the gas diffusion layer6B, as in the first and second embodiments.

While certain embodiments of the invention are described above, the invention may include other embodiments and modifications without deviating from the subject matter or scope of the present invention and may be varied in the range of the claims. For example, the projection32may be formed on the first mold cast25A. Further, as long as the pre-assembly21can be retained and supported at the time of the injection-molding operation, the projection is not necessarily formed.