JP2009129584A - Manufacturing method of fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel cell stack capable of compressing a cell laminated body even without using a large-scale jig. <P>SOLUTION: After carrying out a laminating process of constituting a cell laminated body 3 by laminating a plurality of unit cells 2, the inside of the cell laminated body 3 is depressurized, whereby, a compression process of compressing the cell laminated body 3 is to be carried out in a cell lamination direction. Depressurization is done by vacuuming the inside of the cell laminated body 3, in which, the cell laminated body 3 is compressed by a difference of pressure from atmospheric pressure outside the cell laminated body 3. Further, at the time of the compression process, leak inspection is also carried out based on a vacuum degree of the cell laminated body 3. If an elastic module 10 is laminated on the cell laminated body 3 before the compression process, the cell laminated body 3 can be compressed with the use of its weight. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a fuel cell stack, and more particularly to a compression technique for a cell stack formed by stacking a plurality of single cells.

  The fuel cell stack has a cell stack formed by stacking a plurality of single cells that are basic units of a fuel cell in series (see, for example, Patent Document 1). A solid polymer type single cell is formed by holding a MEA (Membrane Electrode Assembly) between a pair of separators. In patent document 1, when manufacturing a single cell by lamination | stacking of each structural member, each structural member, such as an electrode, is stabilized with respect to a support structure using a vacuum device.

As a manufacturing process of a fuel cell stack, it is widely known that a cell stack is tightened in a stacking direction and tension plates are applied between end plates at both ends of the fuel cell stack. By tightening the cell stack, the electrolyte membrane is reduced (thinned), and the gasket or the like that seals between the separators is crushed and sealed. At this time, the cell stack is compressed until a tension plate can be applied in the stacking direction. This compression is performed by driving a pressure jig against the stacking jig on which the cell stack is set. Is going on.
JP 2006-505096 A

  Patent Document 1 discloses a method of stacking single cell constituent members. However, Patent Document 1 does not disclose any compression of the cell stack, and it is necessary to use a pressure jig as in the above-described prior art to compress the cell stack. However, in order to receive the fastening load by the pressure jig with the lamination jig, it is necessary to ensure the rigidity of the lamination jig to be high, and the lamination jig itself becomes large.

  An object of the present invention is to provide a method of manufacturing a fuel cell stack capable of compressing a cell stack without using a large jig.

  In order to achieve the above object, a method of manufacturing a fuel cell stack according to the present invention includes a stacking step of stacking a plurality of single cells to form a cell stack, and stacking single cells by reducing the pressure inside the cell stack. A compression step of compressing the cell stack in the direction.

  According to the present invention, the cell stack can be compressed by using a device (for example, a vacuum pump) for reducing the pressure inside the cell stack. This eliminates the need for a pressurization mechanism that has been conventionally required, and the cell stack can be compressed without using a large jig.

  Preferably, in the compression step, the pressure is reduced by evacuating the inside of the cell stack.

  According to this configuration, the inside of the cell stack can be decompressed with a simple method and with certainty.

  More preferably, the cell stack is inspected for leak based on the degree of vacuum inside the cell stack during the compression step.

  By doing so, the cell stack can be compressed and the leak inspection can be performed at the same time, so that it is not necessary to perform the leak inspection in the final process of manufacturing the fuel cell stack. Therefore, a series of manufacturing steps can be shortened.

  Preferably, the compression step is performed outside the cell stack under atmospheric pressure.

  By doing so, the cell stack can be compressed by the differential pressure inside and outside the cell stack without providing a large chamber outside the cell stack.

  Preferably, the cell stack has a fluid flow path therein, and the compression step is preferably performed by sucking a gas in the fluid flow path from one end side of the cell stack.

  By carrying out like this, a cell laminated body can be compressed using the fluid flow path inside a cell laminated body effectively.

  More preferably, the fluid flow path includes a fuel gas flow path, an oxidant gas flow path, and a refrigerant flow path, and the compression step simultaneously sucks the gas in the fuel gas flow path, the oxidant gas flow path, and the refrigerant flow path. It is good to do by.

  By carrying out like this, the pressure reduction effect inside a cell laminated body can be heightened, and a cell laminated body can be compressed rapidly.

  Preferably, the stacking step includes a first insulating plate, a first current collecting plate, a cell stack, a second current collecting plate, a second insulating plate, and an elastic member on the first end plate of the fuel cell stack. The modules are stacked in order in the direction of gravity, and the elastic module is preferably for applying a compressive load to the cell stack by elastic force.

  By doing so, since the elastic modules and the like are laminated before the compression step, it is possible to compress the cell laminate using not only the compression by decompression but also the own weight of the elastic modules and the like.

  More preferably, in the manufacturing method, after the compression step, the second end plate is stacked on the elastic module, and the first end plate and the second end plate are connected by a connecting member outside the cell stack. It is good to further provide an assembly step.

  More preferably, after the assembly process, the compression load applied to the cell laminate by the elastic module may be adjusted using an adjustment screw.

  By carrying out like this, the compressive load to a cell laminated body can be set to a predetermined value easily.

  More preferably, the elastic module is pre-compressed.

  By doing so, the stroke of the adjusting screw after the assembling process can be reduced, and workability can be improved.

  Preferably, the stacking step is performed using a jig that supports the cell stack so that the stacking direction of the single cells is inclined with respect to the direction of gravity, and the jig is opposite to the introduction side of the single cells. It is preferable to support the cell stack so that is lower.

  By doing so, compared to the case where the stacking direction and the gravity direction match, it becomes easier to introduce the single cell into the jig in the stacking step, so that workability can be improved.

  Preferably, the area for executing the lamination process and the area for executing the compression process are on the same production line, and the cell stack after the lamination process is conveyed on the production line toward the area for executing the compression process. Good.

  By carrying out like this, a lamination process and a compression process can be performed in a separate area, respectively, and it becomes possible to divide a series of manufacturing processes. As a result, the fuel cell stack can be rapidly mass-produced. The production line is more preferably a conveyor type.

  According to the method for manufacturing a fuel cell stack of the present invention, the cell stack can be compressed without using a large jig.

  Hereinafter, a fuel cell stack manufacturing method according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. First, the structure of the fuel cell stack will be described. Here, a solid polymer fuel cell stack suitable for a vehicle will be described as an example. This type of fuel cell stack is suitable for a vehicle, but is not limited thereto, and can be mounted on a self-propelled mobile body such as a ship, an airplane, and a robot, or can be used as a stationary power source. Is possible.

  As shown in FIGS. 1 and 2, the fuel cell stack 1 includes a cell stack 3 in which single cells 2 that are basic units are stacked. The cell stack 3 is formed by stacking, for example, about 200 to 400 single cells 2. Current collector plates 5a and 5b, insulating plates 6a and 6b, and end plates 7a and 7b are sequentially stacked on the outside of the single cell 2 positioned at both ends of the cell stack 3, and the cell stack is formed by tension plates 8 and 8. The stacked state of the body 3 and the like is constrained. The tension plates 8, 8 are bridged between the end plates 7 a, 7 b so as to face each other outside the cell stack 3, and are fixed to these with bolts 9. An elastic module 10 is provided in series with the cell stack 3 between one end plate 7b and the insulating plate 6b.

  The elastic module 10 applies a compressive load (fastening force) to the cell stack 3 by an elastic force, and includes, for example, a plurality of elastic bodies 12 between a pair of plates 11 and 11. The compressive load applied to the cell laminate 3 can be adjusted by changing the axial length of the cell stack 3 with, for example, a so-called worm screw adjusting screw 13. The adjusting screw 13 is screwed between the end plate 7b and one plate 11 or both of them, and is configured to be operable from the outer surface side of the end plate 7b. With such a configuration of the fuel cell stack 1, the cell stack 3 is in a state where a predetermined compressive load (fastening force) is applied in the stacking direction of the single cells 2 (hereinafter referred to as “cell stacking direction”). .

  The fuel gas, the oxidizing gas, and the refrigerant are supplied to the manifold 20a in the cell stack 3 from the supply pipe 18 connected to the supply ports 15a, 16a, and 17a of the end plate 7a. Thereafter, the fuel gas, the oxidizing gas, and the refrigerant flow in the planar direction of the single cell 2 while flowing through the manifold 20a extending in the cell stacking direction. Finally, the fuel gas, the oxidizing gas and the refrigerant flow from the manifold 20b in the cell stack 3 extending in the cell stacking direction to the discharge pipe 19 connected to the discharge ports 15b, 16b and 17b of the end plate 7. Then, the fuel cell stack 1 is discharged.

  The supply pipe 18, the discharge pipe 19, and the manifolds 20 a and 20 b are provided corresponding to the fluids of the fuel gas, the oxidizing gas, and the refrigerant. In FIG. . Further, the fuel gas is a hydrogen gas containing hydrogen, and the oxidizing gas is a gas containing an oxidant represented by oxygen or air. The fuel gas and the oxidizing gas may be collectively referred to as a reaction gas. The refrigerant is, for example, cooling water.

As shown in FIG. 3, the single cell 2 includes an MEA 20 and a pair of separators 22A and 22B.
The MEA 20 (membrane-electrode assembly) includes an electrolyte membrane 30 made of an ion exchange membrane and a pair of electrodes 32A and 32B sandwiching the electrolyte membrane 30. The electrodes 32A and 32B are obtained by binding a catalyst layer made of, for example, platinum to a diffusion layer made of, for example, a porous carbon material. The diffusion layer of the electrode 32A (anode) faces the fuel gas flow path 40 of the separator 22A, and has a function of allowing the fuel gas to pass therethrough and a function of electrically connecting the catalyst layer and the separator 22A. On the other hand, the diffusion layer of the electrode 32B (cathode) faces the oxidizing gas channel 42 of the separator 22B, and has a function of allowing the oxidizing gas to pass therethrough and a function of electrically connecting the catalyst layer and the separator 22B. .

  The separators 22A and 22B are made of a gas impermeable conductive material. Examples of the conductive material include carbon, a hard resin having conductivity, and metals such as aluminum and stainless steel. In the present embodiment, the separators 22A and 22B are so-called metal separators whose base material is a plate-like metal, and are formed in a rectangular shape in plan view. A first seal material 51 and a second seal 52 that are gaskets, for example, are provided on the outer peripheral edges of the separators 22A and 22B. The first sealing material 51 seals between the adjacent single cells 2 and 2, and the second sealing material 52 seals between the separator 22 </ b> A and the separator 22 </ b> B in each single cell 2.

  The separator 22A has a fuel gas channel 40 on the front surface and a refrigerant channel 44A on the back surface. The separator 22B has an oxidizing gas channel 42 on the front surface and a refrigerant channel 44B on the back surface. One refrigerant flow path 44A of two adjacent single cells 2 and 2 communicates with the other refrigerant flow path 44B, whereby a refrigerant flow path for supplying a refrigerant between the single cells 2 and 2 is formed. When the fuel gas channel 40 supplies fuel gas to the electrode 32A and the oxidizing gas channel 42 supplies oxidizing gas to the electrode 32B, an electrochemical reaction occurs in the MEA 20 and an electromotive force is obtained. In addition, this electrochemical reaction generates water and generates heat on the electrode 32B side. And since a refrigerant | coolant flows into a refrigerant flow path (44A, 44B), the heat | fever of the single cell 2 is reduced and the operating temperature of the fuel cell stack 1 is maintained in a predetermined range.

  The fuel gas channel 40 and the refrigerant channel 44A on both sides of the separator 22A are simultaneously formed by press molding of the separator 22A, and the oxidizing gas channel 42 and the refrigerant channel 44B on both sides of the separator 22B are formed by press molding of the separator 22B. Formed simultaneously. That is, in the separators 22A and 22B, the concavo-convex shape for forming the fluid flow path is reversed between the front surface and the back surface. The fuel gas passage 40, the oxidizing gas passage 42, and the refrigerant passages 44A and 44B are configured as straight passages in which repetition of unevenness extends in one direction or serpentine passages having a folded portion in the middle.

  Next, a method for manufacturing the fuel cell stack 1 will be described with reference to FIG. Here, a so-called tandem fuel cell stack 1 will be described as an example. Needless to say, the present manufacturing method can also be applied to the fuel cell stack 1 that is not a tandem type as shown in FIGS.

  The tandem fuel cell stack 1 includes two cell stacks 3 and 3 as power generation modules, and the two cell stacks 3 and 3 commonly use a pair of end plates 7a and 7b. Therefore, as shown in FIG. 4F, the current collecting plates 5a and 5b, the insulating plates 6a and 6b, the tension plates 8 and 8 and the elastic module 10 are provided for each cell stack 3. . In order to correspond to the two cell stacks 3 and 3, each of the end plates 7a and 7b is provided with two supply ports 15a, 16a and 17a and two discharge ports 15b, 16b and 17b.

  This manufacturing method is divided so that a series of steps relating to the manufacture of the fuel cell stack 1 is executed in a plurality of areas (stations). For example, in one conveyor-type production line 100, the stacking jig 110 is sequentially conveyed to each area by an endless conveyor. Then, an operator or a working robot sets the end plate 7a on the jig 110 (FIG. 4A), stacks the single cells 2 and the like (FIG. 4B), and stacks the elastic module 10 (FIG. 4). (C)), compression of the cell stack 3 (FIG. 4 (d)), assembly of the tension plate 8 (FIG. 4 (e)), and main pressurization (FIG. 4 (f)) with the adjusting screw 13 are executed. . These are all performed under atmospheric pressure. The conveyor may be a circuit conveyor. Further, a turntable type production line 100 may be adopted instead of the conveyor type.

  First, as shown in FIG. 4A, one end plate 7a is set horizontally on, for example, a plate-like jig 110. For example, the jig 110 is provided with an alignment mark for defining the installation position of the end plate 7a. However, an object (for example, a pressure jig) that becomes an obstacle in the setting work of the end plate 7a is not arranged above the jig 110, and this setting work can be easily performed. Yes. This also applies to FIGS. 4B to 4F.

  Next, as shown in FIG. 4B, an insulating plate 6a and a current collecting plate 5a are stacked on the left and right sides of the end plate 7a, respectively, and a predetermined number of single cells 2 are stacked thereon. The two cell stacks 3 and 3 are formed. Further, the current collector plate 5 b and the insulating plate 6 b are stacked on the cell stack 3. Although not shown, the jig 110 has a portion extending in the vertical direction, and the single cells 2 and the like are stacked using this portion as a reference for stacking. Specifically, the single cell 2 or the like is stacked while adjusting the position of the single cell 2 or the like in the plane direction to a specified position by bringing the end portion of the single cell 2 or the like into contact with a portion serving as a stacking reference. Note that the process shown in FIG. 4B may be further divided according to the production amount.

  Next, as shown in FIG. 4 (c), the elastic modules 10 and 10 are laminated on the insulating plates 6 b and 6 b on the cell laminates 3 and 3. The cell stack 3 is slightly compressed in the cell stacking direction under the weight of the elastic module 10. Further, the cell stack 3 is slightly compressed in the cell stacking direction by its own weight. This compression is mainly due to the crushing of the first sealing material 51 and the second sealing material 52, and the length from the end plate 7a to the elastic module 10 is L after the compression.

  Note that the elastic module 10 to which a preload is applied, that is, the pre-compressed elastic module 10 may be used. By doing so, the stroke of the adjusting screw 13 can be reduced in the step of FIG. Alternatively, a predetermined load or more may be applied to the elastic body 12 of the elastic module 10 using a stopper, and the load of the elastic body 12 may be released by removing the stopper after the step of FIG.

  Subsequently, as illustrated in FIG. 4D, the cell stacks 3 and 3 are further compressed in the cell stacking direction using the vacuum pump 120. The vacuum pump 120 reduces the pressure by evacuating the cell stacks 3 and 3 through the air pipe 121.

  Specifically, the six connection ends of the air pipe 121 are connected to the supply ports 15a, 16a, and 17a and the discharge ports 15b, 16b, and 17b of the one cell stack 3. Similarly, the six connection end portions of the air pipe 121 are connected to the other cell stack 3. Thereafter, the vacuum pump 120 is driven, and the suction of air (gas) in the fuel gas passage 40, the oxidizing gas passage 42, and the refrigerant passages (44A, 44B) is started at the same time. Vacuum.

  Due to this evacuation, the cell stacks 3 and 3 are compressed in the cell stacking direction due to the pressure difference between the outside of the cell stacks 3 and 3 and the inside of the cell stacks 3 and 3 at atmospheric pressure. . This compression is mainly due to the crushing of the first sealing material 51 and the second sealing material 52 and the reduction of the electrolyte membrane 30, and is performed up to a length l that allows the tension plate 8 to be assembled. . The length l is the length from the end plate 7a to the elastic module 10 and is smaller than the length L. In addition, the aspect which branches the air piping 121 is arbitrary, and the hole for inserting the air piping 121 is formed in the jig 110.

  Here, in the step shown in FIG. 4D, the cell stacks 3 and 3 may be inspected for leakage at the same time. Specifically, it is preferable to monitor the degree of vacuum inside the cell stacks 3 and 3 and perform a leak inspection based on the result. For example, the degree of vacuum may be monitored by arranging the sensor 122 between the vacuum pump 120 and the cell stack 3, but here the sensor 122 is provided in the air pipe 121. Preferably, the sensor 122 may be provided in a portion before the branch of the air pipe 121 and close to the vacuum pump 120. When the sensor 122 detects the deterioration of the degree of vacuum, a leak has occurred. As the cause, for example, the first sealing material 51 and the second sealing material 52 are not properly sealed. Is mentioned.

  In this way, by performing the leak inspection during the compression process shown in FIG. 4D, it is not necessary to perform the leak inspection only for confirmation before the power generation inspection after the fuel cell stack 1 is manufactured. Thereby, a series of manufacturing processes of the fuel cell stack 1 can be shortened. Then, after the compression process including the leak inspection is completed, the driving of the vacuum pump 120 is stopped, and the jig 110 is transported to the next assembly process area.

  In the assembling step, as shown in FIG. 4 (e), end plates 7 b are stacked on the elastic modules 10 and 10, and the end plates 7 a and 7 b are connected by a tension plate 8. For example, the front and rear between the end plates 7a and 7b are connected by two tension plates 8, respectively.

  Finally, as shown in FIG. 4 (f), the compression load applied to the cell laminates 3, 3 by the elastic modules 10, 10 is adjusted using the adjusting screws 13, 13. By this adjustment, the compressive load on the cell laminates 3 and 3 is set to a predetermined value (specified load). After this setting, a power generation inspection of the fuel cell stack 1 may be performed on the conveyor.

  According to the manufacturing method of the fuel cell stack 1 of the present embodiment described above, the cell stack 3 is compressed using the differential pressure due to vacuum, so that no pressing mechanism is required for the jig 100. Thereby, it is not necessary to use a large jig, the rigidity of the jig 100 can be set low, the weight can be reduced, and the jig 100 itself can be simplified. Further, since the production line 100 can be a conveyor type, the fuel cell stack 1 can be rapidly mass-produced.

  In addition, in the compression process shown in FIG.4 (d), although the inside of the cell laminated body 3 was pressure-reduced to the vacuum state, if the cell laminated body 3 can be compressed, it does not need to be pressure-reduced to a vacuum state. On the other hand, the external atmosphere of the cell stack 3 can be under a pressure higher than atmospheric pressure.

<Modification>
Next, with reference to FIG. 5, the jig | tool 200 of a preferable aspect is demonstrated. This jig 200 can be used in the production line 100 shown in FIGS. As shown in FIG. 5A, the jig 200 supports the cell stack 3 so that the cell stacking direction is inclined with respect to the direction of gravity.

  Specifically, the jig 200 includes a base plate 210 on which the base plate 7a is placed, and a support plate 220 that supports side portions of the cell stack 3 and the like. The base plate 210 is configured to be transportable on the conveyor of the production line 100. The base plate 110 is configured to be removable from the support plate 220. The base plate 210 is inclined, for example, by 15 ° to 45 °, and the introduction side of the single cell 2 is positioned higher than the opposite side (that is, the support plate 220 side). The support plate 220 extends at a right angle to the base plate 210, and supports the end of the single cell 2 or the like by contacting the end. That is, the support plate 220 is a reference for stacking the single cells 2 and the like.

  By using such a jig 200, each constituent member is introduced into the jig 200 in the stacking process shown in FIGS. 4A to 4C, compared to the case where the cell stacking direction and the gravity direction match. Easy to do. Thereby, workability | operativity in a lamination process can be improved. In addition, after the main pressurization step shown in FIG. 4 (f), the operator tilts the jig 200 to level the fuel cell stack 1 horizontally as shown in FIG. 210 can be removed. If the base plate 210 is removed, the auxiliary machine and the distribution pipe 250 can be assembled to the end plate 7a. In this respect, the workability can be improved.

1 is a perspective view of a fuel cell stack according to an embodiment. It is a sectional side view which shows a part of fuel cell stack concerning an embodiment in section. It is sectional drawing of the cell laminated body of the fuel cell stack which concerns on embodiment. It is a schematic diagram which shows a series of manufacturing processes in the manufacturing method of the fuel cell stack which concerns on embodiment. It is a side view which shows typically the jig | tool which concerns on the modification of embodiment with a fuel cell stack, (a) is a jig | tool before completion | finish of manufacture of a fuel cell stack, (b) inclines after completion | finish of manufacture of a fuel cell stack. (C) shows how the piping is attached to the fuel cell stack on the jig from which the base plate has been removed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack, 2 ... Single cell, 3 ... Cell laminated body, 5a, 5b ... Current collecting plate, 6a, 6b ... Insulating plate, 7a, 7b ... End plate, 8 ... Tension plate (connection member), 10 ... Elastic module, 20 ... MEA, 40 ... fuel gas passage, 42 ... oxidizing gas passage, 44A, 44B ... refrigerant passage, 100 ... production line, 110 ... jig, 120 ... vacuum pump, 200 ... jig

Claims (12)

A stacking step of stacking a plurality of single cells to form a cell stack;
And a compressing step of compressing the cell stack in the stacking direction of the single cells by depressurizing the inside of the cell stack.   The method of manufacturing a fuel cell stack according to claim 1, wherein in the compression step, the pressure is reduced by evacuating the inside of the cell stack.   The method for manufacturing a fuel cell stack according to claim 2, wherein a leak inspection of the cell stack is performed based on a degree of vacuum inside the cell stack during the compression step.   4. The method of manufacturing a fuel cell stack according to claim 1, wherein the compression step is performed outside the cell stack at atmospheric pressure. 5. The cell laminate has a fluid flow path inside,
5. The method for manufacturing a fuel cell stack according to claim 1, wherein the compression step is performed by sucking a gas in the fluid flow path from one end side of the cell stack. The fluid flow path includes a fuel gas flow path, an oxidizing gas flow path, and a refrigerant flow path,
6. The method of manufacturing a fuel cell stack according to claim 5, wherein the compression step is performed by simultaneously sucking gases in the fuel gas channel, the oxidizing gas channel, and the refrigerant channel. The stacking step includes a first insulating plate, a first current collecting plate, the cell stack, a second current collecting plate, a second insulating plate, and an elastic member on a first end plate of the fuel cell stack. Laminate modules in order,
The method of manufacturing a fuel cell stack according to any one of claims 1 to 6, wherein the elastic module is for applying a compressive load to the cell stack by an elastic force.   The assembly further includes a step of stacking a second end plate on the elastic module after the compressing step and connecting the first end plate and the second end plate with a connecting member. 8. A method for producing a fuel cell stack according to 7.   The method for manufacturing a fuel cell stack according to claim 8, wherein after the assembling step, a compression load applied to the cell stack by the elastic module is adjusted using an adjustment screw.   The method of manufacturing a fuel cell stack according to claim 9, wherein the elastic module is pre-compressed. The stacking step is performed using a jig that supports the cell stack so that the stacking direction of the single cells is inclined with respect to the direction of gravity.
The fuel cell stack according to any one of claims 1 to 10, wherein the jig supports the cell stack so that the opposite side of the jig is lower than the introduction side of the single cell. Manufacturing method. The area for performing the lamination step and the area for performing the compression step are on the same production line,
The method of manufacturing a fuel cell stack according to any one of claims 1 to 11, wherein the cell stack after the stacking step is transported on the manufacturing line toward an area where the compression step is performed.

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