JP4835029B2 - Manufacturing method of fuel cell - Google Patents

Description

  The present invention relates to a method for manufacturing a fuel cell, and more particularly to an improvement in a method for heating a cell held by a separator.

A cell used in a fuel cell is configured by a polymer membrane sandwiched between separators. This separator is bonded with an adhesive.
Conventionally, as a manufacturing method of a cell, for example, as disclosed in JP-A No. 6-119928, a solid polymer film is sandwiched between gas separators, and the solid polymer film is directly adhered to the gas separator by hot pressing or the like. It was known (Patent Document 1).
Japanese Patent Laid-Open No. 6-11928 (paragraphs 0010, 0011, etc.) JP-A-5-255645 (paragraphs 0001, 0007, 0016) JP-A-8-78028 Japanese Patent Laid-Open No. 2003-22815

  However, in the heat bonding of the separator by hot pressing, the temperature becomes lower as it approaches the center of the cell stack as compared with the portion in contact with the pressure plate, resulting in uneven bonding strength. Further, in the hot press, it takes time to raise the temperature of the plate itself.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a fuel cell and a method for manufacturing the same that can adhere a fuel cell separator evenly.

  In order to achieve the above object, a method of manufacturing a fuel cell including a cell bonded to a plate member formed of a conductive material of the present invention with an adhesive includes attaching an adhesive around the plate member; A step of stacking a plurality of the cells to which the adhesive has been attached and arranging the cells inside the induction coil; and applying a current to the induction coil, and vortexing each of the plate members by a magnetic field generated in the induction coil. Generating an electric current and curing the adhesive with heat generated by the eddy current, and the curing step generates the eddy current around the plate member to which the adhesive is attached. The current applied to the induction coil is controlled so that the temperature is higher than the temperature at which the adhesive can be cured by heat.

  According to the above method, since a uniform magnetic field is generated inside the induction coil, even if a plurality of cells are stacked, a magnetic field equivalent to the cell located at the end is also applied to the cell located in the middle. Affected. For this reason, the amount of eddy current generated in the plate member is also equal to the amount of current, and thus the generated heat is substantially equal. For this reason, it can suppress that a difference arises in the grade of the hardening of an adhesive agent between the laminated | stacked cells. And even if it arrange | positions by laminating | stacking a cell, since an adhesive agent can be hardened uniformly, productivity can be improved.

Here, there is no limitation on the “plate member formed of a conductive material”, and it is only necessary to have conductivity to such an extent that an eddy current can be generated by supplying a magnetic field. Even a pure metal may be a member mixed with a conductive material.
The adhesive may be attached to bond a pair of plate members to form one cell, but may be attached between the cells to bond two cells to each other.

  The “induction coil” is, for example, a solenoid type coil and does not necessarily have to be a cylindrical type. You may provide magnetic bodies, such as an iron core and a ferrite.

  In the present invention, after heating by the induction coil, it is preferable to heat the stacked cells while pressurizing them in the stacking direction. Since almost the same eddy current flows in each of the stacked cells, the amount of heat generated by the eddy current is almost the same, but the heat at the end cell is easy to escape, and conversely the temperature rise is less than that of the middle cell. There is a case. In this regard, according to the present invention, after induction heating, pressure is heated from both sides of the stacked cells, so that the cells in the region near the end can be heated, and the adhesive in all the cells is not uneven. It can be cured.

  The method of manufacturing a fuel cell according to the present invention includes a step of stacking a plurality of cells each having an adhesive attached to a plate member made of a conductive material and placing the cells inside the induction coil, and supplying a current to the induction coil. Applying and generating an eddy current in each of the plate members by a magnetic field generated in the induction coil, and curing the adhesive with heat generated by the eddy current, and in the curing step, The current applied to the induction coil is controlled by the heat generated by the eddy current around the plate member to which the adhesive is adhered so that the temperature is higher than the temperature at which the adhesive can be cured. Along with the heating, the stacked cells are heated while being pressed in the stacking direction.

  As described above, according to the present invention, since the magnetic field equivalent to the cell located at the end is exerted on the cell located in the middle, the productivity is increased by stacking the cells. The adhesive can be cured without unevenness.

(Embodiment 1)
Embodiment 1 of the present invention relates to a specific example in which an induction coil is used for adhesion for forming a cell of a fuel cell. In FIG. 1, the schematic perspective view of the induction heating apparatus 100 of Embodiment 1 is shown. FIG. 2 is a schematic cross-sectional view of the cut surface including the central axis of the induction heating apparatus 100.
As shown in FIG. 1, the induction heating device 100 includes an induction coil 1 and an AC power supply device 2. The cells 31 to 3n (represented by 3x) shown in FIGS. 1 and 2 exemplify the arrangement of the cells in the induction coil 1.

The induction coil 1 is configured by concentrating and rotating conductive wires in a solenoid shape. The winding method is not limited, but a winding method in which a uniform magnetic field is generated in the space for accommodating the cells is preferable. For example, if the infinite length solenoid coil has n turns and the current flowing through the coil is I, the magnetic field φ generated inside is
φ = nI
As long as it is arranged inside the coil, a uniform magnetic field is obtained regardless of the displacement from the central axis. For this reason, it is preferable to configure the induction coil 1 of the induction heating device 100 so that the cells are arranged in a solenoid coil having a certain length.

  Although there is no limitation on the conductive wire constituting the induction coil 1, since the induction coil 1 generates a considerably high magnetic field, the amount of current flowing inside the coil is expected to increase. For this reason, the electrical resistance is as small as possible and is made of a material that can withstand the heat generated inside the coil, for example, copper or aluminum. The diameter of the conductive wire is also set to a diameter that exhibits a sufficient current capacity with respect to the maximum current value flowing through the induction coil 1.

  In addition, the induction coil 1 is configured to have a prismatic shape as a whole, that is, a cross-sectional shape perpendicular to the axis is a square. If it is rotated in such a shape, the cell 3x to be heated can be placed flat and the volumetric efficiency is good. However, you may comprise the induction coil 1 so that the cross-sectional shape perpendicular | vertical to an axial center may be circular so that other shapes, for example, cylindrical shape, may be exhibited.

  The AC power supply device 2 is a power supply device that can pass an AC current of a predetermined frequency, for example, 50 Hz or 60 Hz, which is a frequency of a commercial power supply, to the induction coil 1. The amount of current is determined according to the amount of heat to be generated in the object to be heated (cell).

  As shown in FIG. 3, in the induction heating apparatus 100 of the present invention, a magnetic field is applied to a cell to be heated to generate an eddy current, and the adhesive 32 is cured by heat generated in accordance with the eddy current. Is. From the relationship between the amount of heat to be applied to the adhesive 32 and the current that is actually supplied to the induction coil 1, the amount of current in the induction coil 1 that is sufficient to cure the adhesive 32 is determined, and the alternating current is supplied with that amount of current. Thus, the output of the AC power supply device 2 is set. That is, between the AC current supplied to the induction coil 1 and the heat finally applied to the adhesive 32, the AC current → the magnetic field generated in the induction coil 1 → the eddy current generated by the magnetic field → the eddy current. It goes through an energy conversion process called heat. It is not necessary to directly grasp the amount of the magnetic field or eddy current that is an intermediate energy state, and it is only necessary to grasp the relationship between the alternating current that is the input and the heat generated by the separator 30 that is the output. For this reason, for example, by measuring the relationship between the applied current from the AC power supply device 2 to the induction coil 1 and the surface temperature of the metal plate disposed inside, it should be applied to the induction coil 1 in this embodiment. AC current can be grasped.

  Although not shown, a casing and a guide made of an insulator are provided in the induction coil 1 so that the stacked cells 3x can be stably placed. Also, a loading / unloading device (such as an arm) for loading the cell 3x into the induction coil 1 or unloading the cell 3x from the inside of the induction coil 1 is provided.

  As shown in FIG. 2, one cell 3 x is configured by sandwiching a power generation body 31 responsible for power generation of a fuel cell with a pair of separators 30 and sealing them with an adhesive 32. . Specifically, the periphery of the power generation body 31 is configured by sealing with an adhesive 32 via a resin frame (gasket) (not shown). The present invention relates to an effective heating method for the adhesive 32.

The power generator 31 has, for example, a MEA structure, that is, a laminated structure in which catalyst electrodes in which a catalyst is supported on a porous support layer are formed on both sides of a polymer electrolyte membrane. Various other options are conceivable for the structure of the power generation body 31 depending on the type of the target fuel cell. For example, a solid oxide fuel cell has a basic structure in which an electrolyte such as zirconia is sandwiched between a cathode electrode such as lanthanum manganite and an anode electrode such as nickel. In the case of a molten carbonate fuel cell, an electrolyte plate in which carbonate is impregnated in a holding material such as LiAlO ₂ is sandwiched between an anode electrode and a cathode electrode. In the case of a polymer electrolyte fuel cell, an electrolyte membrane containing a polymer electrolyte such as a fluorine-based ion exchange membrane is interposed between the anode electrode and the cathode electrode. Those having a sandwiched structure are applicable.

  As shown in FIG. 3, the separator 30 has a flow path 30 disposed on almost the entire surface of the power generation region 35 in order to supply oxidizing gas and hydrogen gas to the cathode electrode side and the anode electrode side of the power generator 31. It has a structure. There is no limitation on the material and structure of the separator, but it is composed of a stainless steel (SUS) flat body called a metal separator or a stainless steel surface obtained with a conductive material and a corrosion-resistant material, and a carbon and resin called a carbon separator. There are things. A metal material that is easy to process, for example, aluminum, iron, titanium, stainless steel, or the like containing carbon is used. In particular, in the present invention, since it is necessary to generate an eddy current in the separator 30 by induction heating, it is necessary that the separator 30 is formed of a conductive material. In this embodiment, a metal separator is used. The separator 30 has a thickness of about 0.05 to 0.3 mm, and is preferably 0.1 mm or less in order to stack a large number.

  A flow path structure 34 is formed in the power generation region 35 of the separator 30. The flow path structure 34 provides a flow path for hydrogen gas, which is a fuel gas, on the surface of the anode-side separator 30 facing the power generator 31, and air, which is an oxidizing gas, on the surface of the cathode-side separator 30. A flow path is provided. The surface of the separator 30 outside the cell 3x provides a coolant flow path. In addition, hydrogen gas, air, and coolant flowing through the flow path structure 34 are supplied from any of a plurality of manifolds 33 provided around the power generation region 35 of the separator 30.

  Here, the cell 3x is arranged so that the surface thereof is perpendicular to the direction of the magnetic field. Further, it is assumed that the geometric center of the cell (separator) and the axis of the induction coil 1 coincide with each other.

  In the configuration of the induction heating apparatus 100, as shown in FIG. 2, cells 3x made of metal are stacked and disposed inside the induction coil 1, and an alternating current is supplied from the alternating current power supply apparatus 2 to the induction coil 1. Then, a magnetic field is generated inside and outside the induction coil 1. As described above, this magnetic field is constant inside the induction coil 1. When a magnetic field penetrates the metallic separator 30, an eddy current ED determined according to the direction of the magnetic field flows as shown in FIG. When this eddy current ED flows, heat is generated. In the present embodiment, the adhesive 32 is cured by heat generated corresponding to the eddy current ED.

  FIG. 4 is a surface temperature distribution diagram showing the relationship between the position of the surface of the separator 30 inside the induction coil 1 and the temperature at that position when a predetermined current is passed. As shown in FIG. 4, an eddy current ED is generated around the geometric center (center of gravity) of the separator 30 that is a metal plate. The farther you go, the higher the amount of heat generated. FIG. 4 is a temperature distribution diagram of the amount of alternating current that flows during processing, Tmax is the maximum temperature around the separator 30, and Tctr is a control temperature at which the adhesive 32 can be cured. The adhesive 32 is applied to the periphery of the separator in order to seal the periphery of the separator 30. When the region bonded by the adhesive 32 is defined as a bonded region, the amount of alternating current is controlled so that the control temperature Tctr is controlled over the entire region of the adhesive region to which the adhesive 32 around the separator 30 is applied. Is controlled, the adhesive 32 is securely bonded.

Next, a method for manufacturing the fuel cell according to Embodiment 1 will be described with reference to the flowchart of FIG. 5 and FIGS.
First, as a first step (S1), as shown in FIG. 6, an adhesive is attached between a pair of separators constituting one cell. Moreover, when manufacturing the laminated body which also made cells adhere | attach, an adhesive agent is made to adhere also between cells. For example, the uncured adhesive 32 is applied to each application surface of the pair of separators 30 using an application means such as the dispenser 5. The area to be applied is an area around the power generation area 35. Although there is no limitation in the kind of the adhesive agent 32, in this embodiment, since it is necessary to harden an adhesive agent by temperature rising, the adhesive agent hardened | cured by heat | fever, such as a thermosetting resin, is utilized. Of course, this adhesive preferably has chemical stability against hydrogen gas, coolant, air (oxygen) and the like used in the fuel cell. For example, an epoxy resin can be applied. The adhesive 32 can be applied to one or both of the pair of separators 30. Here, in addition to the adhesive 32, a pair of separators 30 may be bonded via a spacer.

  As the next step (S2), as shown in the schematic diagram of FIG. 7, the power generator 1 is sandwiched between the anode-side separator 30 and the cathode-side separator 30 while being aligned. In this way, the pair of separators 30 are bonded together to form the structure of the cell 3x. A plurality of such cells 3x are formed. When an adhesive is attached between the cells, the adhesive is attached to one or both separator surfaces, and then the cells are aligned and laminated.

  As the next step (S3), the cells 3x are stacked so that they can be heated by the induction heating device 100, and placed inside the induction coil 1 of the induction heating device 100 by an arm or the like (not shown). At this time, the stacked cells 3x are arranged so that the geometric center of the cells 3x substantially coincides with the axis of the induction coil 1 (see FIG. 1).

  As the next step (S4), an alternating current starts to flow from the alternating current power supply device 2 to the induction coil 1. At this time, a magnetic field is generated inside the induction coil 1 through each cell 3x according to the alternating current (see FIG. 2). Since the separator 30 of each cell 3x is made of metal, an eddy current ED as shown in FIG. 3 is generated, and the periphery of the separator 30 is heated according to the characteristics of FIG. It will harden.

  Waiting for a sufficient time for the adhesive 32 to be cured (S5: NO), and when the time T0 when the adhesive 32 is assumed to be substantially cured has elapsed (S5: YES), the application of the alternating current is stopped. Then, as the next step (S6), the cells 3x stacked by an arm (not shown) or the like are carried out.

  As described above, according to the manufacturing method of the first embodiment, a uniform magnetic field is generated inside the induction coil 1, and therefore, even if a plurality of cells 3x are stacked, the same magnetic field is applied to each cell, and the same vortex An electric current can be generated and similarly generated. For this reason, it is possible to make the degree of hardening of the adhesive 32 uniform between the stacked cells 3x. Moreover, since it can heat-process with the several cell 3x laminated | stacked, productivity can be improved.

  Further, according to the manufacturing method of the first embodiment, since the cell itself generates heat by induction heating and is heated, the heating time of the platen can be shortened compared to the heating method in which the platen is brought into contact.

  In particular, in induction heating, a high-frequency current in the conductor is large on the surface, and a skin effect occurs in which a current that decreases exponentially as it goes inside the conductor, resulting in a high temperature on the separator surface that is applied to the surface. It is suitable as a method for curing the adhesive 32.

(Embodiment 2)
Embodiment 2 of this invention is related with the specific example of the induction heating apparatus which used a fuel induction coil and the pressurization plate together. In FIG. 8, the schematic perspective view of the induction heating apparatus 102 of Embodiment 2 is shown. FIG. 9 is a schematic cross-sectional view of the cut surface including the central axis of the induction heating device 102.

  As shown in FIGS. 8 and 9, the induction heating device 102 is similar to the first embodiment in that the induction heating device 102 includes the induction coil 1 and the AC power supply device 2, but further includes pressure plates 4A and 4B. Is different in that. About the structure of the induction coil 1, the alternating current power supply device 2, and the cell 3x, it is the same as that of Embodiment 1, and abbreviate | omits description.

  The pressurizing plates 4A and 4B constitute a so-called heating press device (hot plate), and can pressurize and heat the laminated body of the cells 3x disposed in the induction coil 1 from the axial direction of the induction coil 1. Is provided. The pressure plates 4A and 4B are provided so as to be transportable in the direction of the arrow in the figure or in the opposite direction by a moving mechanism (not shown). The pressurizing plates 4A and 4B have a shape and size in which the outer shape can be inserted into the induction coil 1 horizontally, and the entire cell 3x that is a pressurized body can be pressed. It has a size. Therefore, the pressure plates 4A and 4B are formed larger than the cell 3x on the plane and smaller than the inner periphery of the induction coil 1. By providing such a structure, the pressure plates 4A and 4B are transported from the axial direction of the induction coil 1 and inserted into the induction coil 1 so that the stacked body of the cells 3x can be pressurized.

  The pressure plates 4A and 4B are configured such that the pressure surface is heated by a heater (not shown). The pressurized object to be pressed, which comes into contact with the pressure plates 4A and 4B, is heated by heat conduction due to heat conduction.

Next, a fuel cell manufacturing method according to Embodiment 2 will be described with reference to the flowchart of FIG.
First, as in the first embodiment, the adhesive 32 is applied to each application surface of the pair of separators 30 using an application means such as the dispenser 5 (see FIG. 6: S10). Next, the power generator 1 is sandwiched between the anode electrode-side separator 30 and the cathode electrode-side separator 30 (see FIG. 7: S11). Next, the cells 3x are stacked so as to be heated by the induction heating device 102, and are placed inside the induction coil 1 of the induction heating device 102 by an arm or the like (not shown) (see FIG. 9: S12). Then, as in the first embodiment, an alternating current is passed from the alternating current power supply device 2 to the induction coil 1, an eddy current ED is generated on the surface of the separator 30, and the adhesive 32 is cured (S13). Then, after waiting for a sufficient time for the adhesive 32 to cure (S14: NO), when the time T1 when the adhesive 32 is assumed to be substantially cured has elapsed (S14: YES), the application of the alternating current is stopped. (S15).

  Now, by induction heating, a current similar to that of the separator disposed at the end is generated for the separator 30 sandwiched in the middle of the stacked body of the cells 3x, and heating is performed, while the separator at the end is Since it is in contact with air, the surface temperature is likely to decrease due to heat dissipation as compared with the internal separator. For this reason, it is considered that the temperature of the adhesive 32 in contact with the separator 30 disposed at the end is lower than that of the adhesive 32 in contact with the separator 30 disposed in the middle, and curing is not sufficiently performed. It is done.

  In the second embodiment, to cope with this, the separator 30 disposed at the end is further heated by the heating plates 4A and 4B. As shown in FIGS. 8 and 9, after the induction heating is finished, the heating plates 4A and 4B are conveyed into the induction coil 1 to sandwich the stacked body of the cells 3x (S16). Then, the surface temperature of the heating plates 4A and 4B is raised with the heater heated (S17), and pressing and heating are continued until heat is also applied to the separator at the end (S18: NO). When a sufficient time T2 has passed to heat the end separator 30 and cure the adhesive 32 (S18: YES), the heating plates 4A and 4B are conveyed in the direction opposite to the arrows in FIGS. Then, the stacked body of the cells 3x is carried out by an arm or the like (not shown) (S19).

  In the above manufacturing method, press heating is performed after induction heating, but there is no problem even if the heating plates 4A and 4B themselves generate heat due to eddy current generated by the magnetic field generated in the induction coil 1. In such a case, the induction heating and the pressure heating may be performed in parallel. That is, pressurization and heating by the heating plates 4A and 4B are performed while supplying current from the AC power supply device 2 to the induction coil 1.

  As described above, according to the heating device and the heating method of the second embodiment, after induction heating, pressure heating is performed by the heating plates 4A and 4B from both sides of the stacked cells 3x. However, sufficient heating can be performed and the adhesive in all cells can be cured without unevenness. Even if induction heating and pressure heating are used simultaneously, the above-described effects can be obtained.

(Other variations)
The present invention is not limited to the above embodiment, and can be applied with various modifications.
For example, in the induction heating device in the above embodiment, magnetic flux induction means such as ferrite and iron core is not provided, but these magnetic flux induction means may be provided around the induction coil 1. By providing such magnetic flux induction means, it is possible to eliminate leakage of magnetic flux, effectively convert electric energy flowing through the induction coil 1 into magnetic flux, and convert it into eddy current on the separator surface.

  In the second embodiment, the magnetic flux guiding means is movable inside the induction coil 1 and further configured to be directly heated by a heater, so that the heating plates 4A and 4B in the second embodiment are also used as the magnetic flux guiding means. It is also possible.

Schematic perspective view of the induction heating apparatus in the first embodiment Schematic cross-sectional view of the induction heating apparatus in the first embodiment Schematic plan view of the separator during induction heating in Embodiment 1 Distribution diagram of induction coil internal position and surface temperature of induction heating device of the present invention Flowchart of fuel cell manufacturing method according to Embodiment 1 Explanatory drawing of the adhesive application process in this embodiment Explanatory drawing of the bonding process of the cell in this embodiment The schematic perspective view of the induction heating apparatus in this Embodiment 2. Schematic sectional view of the induction heating apparatus in the second embodiment Flowchart of fuel cell manufacturing method according to Embodiment 2

Explanation of symbols

1 induction coil, 2 AC power supply, 3,3x, 3 ₁ ~3 _n cell, 5 dispenser 31 generators, 32 adhesive, 33 manifold, 34 channel structure, 35 the power generation area, 100,102 induction heater

Claims (3)

A method of manufacturing a fuel cell comprising a cell bonded with an adhesive to a plate member formed of a conductive material,
Adhering an adhesive around the plate member;
Placing inside the induction coil the cells with attached the adhesive by stacking a plurality of,
It said induction coil a current is applied to the by a magnetic field generated in the induction coil to generate an eddy current in each of said plate member, and a step of curing the adhesive by heat generated by the eddy currents,
In the curing step, the current applied to the induction coil is controlled so that the temperature of the adhesive can be set to be higher than the temperature at which the adhesive can be cured by heat generated by the eddy current around the plate member to which the adhesive is adhered. To do,
A method for producing a fuel cell, characterized by comprising: A method of manufacturing a fuel cell according to claim 1,
A method for manufacturing a fuel cell, comprising heating the stacked cells while pressing them in the stacking direction after heating by the induction coil. A fuel cell manufacturing method comprising:
A step of stacking a plurality of cells each having an adhesive attached to a plate member made of a conductive material and arranging the cells inside the induction coil;
Said induction coil a current is applied to the by a magnetic field generated in the induction coil to generate an eddy current in each of said plate members, comprising the steps of Ru curing the adhesive by heat generated by the eddy currents, the ,
In the curing step,
Controlling the current to be applied to the induction coil so that the temperature of the adhesive is not less than the temperature at which the adhesive can be cured by heat generated by the eddy current around the plate member to which the adhesive is attached;
In parallel with the heating by the induction coil, it is heated under pressure the laminated cell in the lamination direction,
A method for producing a fuel cell, characterized by comprising:

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