JP3616787B2 - Fuel cell stack separator and method of manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell stack separator and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, this type of embodiment is described in JP-A-10-255824. The purpose of this conventional example is to mass-produce stack separators that are excellent in airtightness without causing leakage of reaction gas. Generally, it is an object of this type of invention to provide a separator that can achieve airtightness, lightness, mass productivity (low cost) and the like.
[0003]
However, it cannot be said that the conventional example sufficiently fulfills the object of the invention with respect to airtightness, lightness and mass productivity. One reason for this is that, when forming a separator as an electromotive portion, a method is employed in which the upper and lower side surfaces of the separator base material are pressed to form the flow paths.
[0004]
In the conventional example, in order to improve the airtightness, it is necessary to doublely provide a protruding wall (lip) around the peripheral edge portion of the separator substrate. Therefore, the separator base material itself needs to have a certain thickness. For example, when the separator base material is molded, it is necessary to stack a plurality of flexible graphite sheets. This idea is excellent in that the protruding wall (lip) is pressure-bonded to improve the airtightness of the part, but it is contrary to the idea of making the separator substrate itself thin. Further, there is an idea that the elastic packing is fitted into the double projecting wall provided around the peripheral edge, but the operation of fitting the elastic packing into the circumferential groove is not easy.
[0005]
[Problems to be solved by the invention]
The first object of the present invention is to provide a fuel cell stack separator S that is excellent in light weight and does not require the use of elastic packing. The second object is to provide a method of manufacturing the separator S suitable for mass production. The third object is that the width of the frame member itself having a packing function can be narrowed (the frame is lightened).
[0006]
[Means for Solving the Problems]
The fuel cell stack separator of the present invention comprises a thin sheet-like flexible expanded graphite base plate 1 having through-holes 2 at four corners, a notch for flow passage 4, a supply hole 5 that can communicate with the through-hole, and a discharge. A pair of thin sheet-like expanded graphite channel plates 3 having holes 6 and a pair of thin frame-like expanded graphite frame plates 8 having a wide opening window portion 19 and having a packing function and having a packing function. An expanded graphite channel plate 3 is joined to both sides of the expanded graphite base plate 1 in a sandwich manner with the graphite base plate 1 as a reference, and the expanded graphite frame is attached to the wall surfaces of the upper and lower expanded graphite channel plates 3 and 3. The plates 8 and 8 are joined and pressure-bonded in a sandwich shape.
[0007]
Further, the method for manufacturing a separator for a fuel cell stack according to the present invention includes an expanded graphite base plate forming step A for forming a thin sheet-like expanded graphite base plate 1 cut into a predetermined size and having through holes 2 at four corners; A thin sheet-like expanded graphite channel plate forming step B for forming the expanded graphite channel plate 3 having the channel notch 4, the supply hole 5 and the discharge hole 6, and a thin frame shape having a wide opening window 19. The expanded graphite frame plate forming step C for forming the expanded graphite frame plate 8 and the expanded graphite base plate 1 formed in the expanded graphite base plate forming step A are positioned in the middle, and the expanded graphite base plate 1 is used as a reference. The expanded graphite channel plate 3 formed in the expanded graphite channel plate forming step B is joined to both sides of the expanded graphite base plate 1 in a sandwich shape so as to be back to back. Road boards 3, 3 Characterized in that it comprises a five plate bonding and pressure bonding step of bonding the expanded graphite frame plate 8, 8 which is the form in expanded graphite frame plate forming step C on the wall in a sandwich-like D.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
First, before explaining the invention of the manufacturing method of the present invention, the structure of a stack separator S for a fuel cell obtained by the method will be described. 1 to 3 are explanatory schematic diagrams showing an example of the stack separator S. FIG.
[0009]
The separator S of the present invention is characterized in that each of the five thin sheet-like members is an expanded graphite sheet having a certain degree of hardness and flexibility, such as an underlay. Further, the separator S of the present invention is characterized in that no packing annular groove (rectangular groove, circular groove or the like) surrounding the flow path is formed, and therefore no packing is provided to fit into the annular groove. .
[0010]
Reference numeral 1 denotes a sheet positioned in the middle of the five thin sheet-like members. This sheet will be referred to as an “expanded graphite base plate”. The expanded graphite base plate 1 is a rectangular plate having a thickness of about 1 mm in this embodiment. Regarding the size, for example, the length is 200 mm in length and 180 mm in width. Of course, the vertical and horizontal lengths can be freely set from the viewpoints of what pattern the flow path is formed in and how the size of the holes for the manifold (through holes = supply holes, discharge holes) is to be handled. . The thickness is preferably about 1 mm because there may be a case in which an iron or steel metal fiber or an extremely thin sheet is used as a core material. The expanded graphite base plate 1 is required to be a member having a certain degree of hardness and at least flexibility regardless of whether or not the core material such as the metal fiber is included.
[0011]
Reference numeral 2 denotes a plurality of through holes for the manifold, and these through holes 2 are formed at the four corners of the expanded graphite base plate 1, respectively.
[0012]
Reference numeral 3 denotes a sheet in which the expanded graphite base plate 1 is sandwiched between five thin sheet members. This sheet will be referred to as an “expanded graphite channel plate”. The expanded graphite flow path plate 3 has the same thickness, shape, size, through-hole, flexibility and the like as the expanded graphite base plate 1.
[0013]
Thus, reference numeral 4 denotes a notch for a channel formed entirely in a double line shape on the expanded graphite channel plate 3 except for the edge 3a. In the present embodiment, the channel cutout 4 is formed from the start side 4a to the end side 4b by drawing a regular meandering line. In general, a separator having such a regular meandering flow path has a manifold discharge hole 6 formed on the diagonal side with respect to the manifold supply hole formed at the corner. Therefore, the expanded graphite channel plate 3 of this embodiment also has a supply hole 5 formed at one of its corners, and the supply hole 5 communicates with the start end 4a of the channel cutout 4. Yes. On the other hand, a discharge hole 6 is formed on the diagonal side with respect to the supply hole 5, and the discharge hole 6 communicates with the terminal end 4 b of the flow path cutout portion 4. The supply hole 5 and the discharge hole 6 are only part of the partitioned flow path.
[0014]
Reference numeral 7 denotes the supply hole 5 on the IN side and the OUT side when the expanded graphite flow path plates 3 and 3 are bonded back to back on the upper and lower side wall surfaces of the expanded graphite base plate 1 with reference to the expanded graphite base plate 1. Communication holes (= parts of flow paths) communicating with the respective discharge holes 6. In FIG. 2, the upper and lower expanded graphite channel plates 3 and 3 are the same, but the lower expanded graphite channel plate 3 is turned upside down on the basis of the expanded graphite base plate 1, and the upper expanded graphite channel It becomes the back-to-back appearance with respect to the road board 3 (note the position of the sign in FIG. 2).
[0015]
These communication holes 7 and 7 are located on the diagonal side with respect to the supply hole 5 and the discharge hole 6. Accordingly, similarly to the expanded graphite base plate 1, the expanded graphite channel plate 3 is also formed with supply holes 5, discharge holes 6 and communication holes 7 at the four corners so as to communicate with the through holes 2 of the expanded graphite base plate 1. .
[0016]
Reference numeral 8 denotes a thin frame-shaped expanded graphite frame plate, and this expanded graphite frame plate 8 is matched to the wall surface of the expanded graphite channel plate 3 in order to exhibit a packing function. The expanded graphite flow path plate 3 is not related to the flow path, but is a member for exhibiting the packing function. Therefore, the expanded graphite flow path plate 3 does not block the supply hole 5, the discharge hole 6 and the like described above. It is crimped in a sandwich shape up and down. In this embodiment, in order to reduce the weight of the expanded graphite frame plate 8, the width of the edge portion 8a is narrowed.
[0017]
Although FIG. 1 is conceptually illustrated for convenience of explanation regardless of the thickness and dimensions, as shown in FIGS. 2 and 3, the expanded graphite base plate 1 positioned in the middle is used as a reference. The flow path plate 3 and the expanded graphite frame plate 8 are integrally laminated in a sandwich shape from above and below to form one separator S.
[0018]
Therefore, a method for manufacturing the separator S will be described. In the description of the method, the reference numeral of the separator S is used as it is, and a duplicate description is omitted.
[0019]
FIG. 4 shows an expanded graphite base plate forming step A. In the expanded graphite base plate forming step A, the rolled expanded graphite sheet 10 is guided to the lower side of the cutting machine 12 through a plurality of guide rollers 11 and is expanded by the cutter 13 that moves up and down of the cutting machine 12. A cutting process A1 for appropriately cutting the graphite sheet 10 into a predetermined dimension, a predetermined dimension expanded graphite sheet 10A obtained by the cutting process A1 as a base material, press working using a through-hole forming die 14, and And a manifold through-hole forming step A2 for forming the expanded graphite base plate 1 having the through-holes 2 at the four corners.
[0020]
Next, B moves up and down a flat plate-like notch forming machine 16 having a flow path forming blade 15 on one side to a predetermined position, so that an expanded graphite flow having a flow path notch part 4, a supply hole 5 and a discharge hole 6 is obtained. This is an expanded graphite channel plate forming step for forming the channel plate 3. In this expanded graphite channel plate forming step B, for example, a meandering opening = notch is formed by the channel forming blade 15 of the notch forming machine 16, and not a groove.
[0021]
Next, C is a thin frame shape having a wide rectangular opening window 19 by moving a flat frame-shaped frame forming machine 18 having a frame forming blade 17 projecting in a rectangular shape on one side surface to a predetermined position. This is an expanded graphite frame plate forming step for forming the expanded graphite frame plate 8.
[0022]
Finally, D is a sandwich in which the expanded graphite base plate 1 is positioned in the middle and the expanded graphite channel plate 3 is placed on both sides of the expanded graphite base plate 1 with the expanded graphite base plate 1 as a reference. In addition, the expanded graphite frame plates 8 and 8 are joined to the wall surfaces of the upper and lower expanded graphite flow path plates 3 and 3 in a sandwich shape. Thereby, the separator S of the present invention is completed.
[0023]
In the five-plate joining / crimping step D, when the expanded graphite channel plate 3 is placed on the upper and lower wall surfaces of the expanded graphite base plate 1, the notched portion 4 of the expanded graphite channel plate 3 is cut into grooves. It will be like a state. Therefore, when the expanded graphite channel plate 3 is fixed integrally to the expanded graphite base plate 1, a channel for oxidant gas or fuel gas is completed. Further, when thin expanded graphite sheets of a total of 5 sheets are laminated integrally, the edge portion 8a of the expanded graphite frame plates 8, 8 fulfills the function of packing. Therefore, the expanded graphite frame plates 8 and 8 themselves of the separator S serve as packing materials.
[0024]
The separator S obtained by the above production method is used for producing a fuel cell stack. When assembling the separator S, for example, as shown in FIG. 5, the separators S have a porous support plate 20, a support current collector 21 having through holes (not shown), and permeable ions having electrodes on both sides. The exchange membrane 22 is interposed, and finally, the fixing plate is fixed integrally by using fixing means such as a fixing plate (not shown), a screw threaded through the hole of the fixing plate, and a nut. There are various fixing methods when assembling the separator S. In the present embodiment, other manifold holes and the like are omitted.
[0025]
【Example】
In the example described in the embodiment of the invention, the notch portion 4 for the expanded graphite channel plate is formed from the start side 4a to the end side 4b in a regular meandering line, It need not be regular serpentine. For example, it may be spiral. The expanded graphite base plate 1 has a thickness of 1 mm and a size of 200 mm in length and 180 mm in width in this embodiment, but the size and shape thereof are not particularly limited. However, the thickness is preferably around 1 mm. Further, the edge portion 8a of the expanded graphite frame plate 8 may be formed wide and a through hole for a manifold may be formed at an appropriate portion, but it is desirable to reduce the size of the edge portion 8a as in this embodiment.
[0026]
【The invention's effect】
(1) Since all the base plates are made of thin sheet-like flexible expanded graphite, they are excellent in lightness and airtightness. In particular, since it is not necessary to use the elastic packing when manufacturing the stack, the manufacturing efficiency can be improved and the disadvantage of work (forgetting to put the elastic packing) can be eliminated.
(2) Since the upper and lower thin sheet-like expanded graphite channel plates 3 and the expanded graphite frame plate 8 do not need to use elastic packing, the separator S suitable for mass production can be provided at low cost.
(3) The width of the frame member itself having a packing function can be reduced (the frame can be reduced in weight).
[Brief description of the drawings]
1 to 4 are explanatory views showing an embodiment of the present invention. FIG. 5 is a schematic explanatory view showing an example of an embodiment of the invention.
FIG. 1 is a conceptual illustration when five expanded graphite sheets constituting a separator are superposed.
FIG. 2 is an exploded perspective view of a separator.
FIG. 3 is a schematic explanatory diagram when five expanded graphite sheets are integrally joined.
FIG. 4 is a process diagram showing a separator manufacturing method.
FIG. 5 is an explanatory diagram illustrating an example of an embodiment.
[Explanation of symbols]
S ... Separator, 1 ... Expanded graphite base plate, 2 ... Through hole, 3 ... Expanded graphite flow path plate, 4 ... Flow path notch, 4a ... Start end, 4b ... Termination, 5 ... Supply hole, 6 ... Discharge hole, DESCRIPTION OF SYMBOLS 7 ... Communication hole, 8 ... Expanded graphite frame board, 8a ... Edge, 10 ... Roll-shaped expanded graphite sheet, 12 ... Cutting machine, 10A ... Predetermined dimension expanded graphite sheet, 16 ... Notch forming machine, 18 ... Frame forming machine, A ... expanded graphite base plate forming step, B ... expanded graphite channel plate forming step, C ... expanded graphite frame plate forming step, D ... five-sheet joining / crimping step D.

Claims (4)

A pair of thin sheet-like expanded graphite having a thin sheet-like flexible expanded graphite base plate 1 having through-holes 2 at four corners, a channel cutout portion 4, and a supply hole 5 and a discharge hole 6 that can communicate with the through-holes, respectively. The expanded graphite base plate is composed of a pair of expanded graphite frame plates 8 having a flow path plate 3, a wide opening window portion 19 and an edge portion 8a having a packing function, and having a packing function. The expanded graphite channel plate 3 is joined to both sides of the plate 1 in a sandwich shape, and the expanded graphite frame plates 8 and 8 are joined and crimped to the wall surfaces of the upper and lower expanded graphite channel plates 3 and 3. A separator for a fuel cell stack. 2. The fuel cell stack separator according to claim 1, wherein the expanded graphite base plate 1, the expanded graphite channel plate 3, and the expanded graphite frame plate 8 are at least flexible materials. 3. The fuel cell stack separator according to claim 2, wherein the expanded graphite base plate 1 has a thickness of about 1 mm. An expanded graphite base plate forming step A for forming a thin sheet-like expanded graphite base plate 1 which is cut to a predetermined size and has through-holes 2 at four corners, a flow path notch portion 4, a supply hole 5 and a discharge hole 6 A thin sheet-like expanded graphite channel plate forming step B for forming the expanded graphite channel plate 3 and an expanded graphite frame plate forming step C for forming the thin frame-like expanded graphite frame plate 8 having the wide opening window 19. The expanded graphite base plate 1 formed in the expanded graphite base plate forming step A is positioned in the middle, and the expanded graphite flow path is formed on both sides of the expanded graphite base plate 1 with reference to the expanded graphite base plate 1. The expanded graphite channel plate 3 formed in the plate forming step B is joined in a sandwich shape so that they are back to back, and the expanded graphite frame plate forming step is formed on the wall surfaces of the upper and lower expanded graphite channel plates 3 and 3. Expanded graphite frame formed of C Five plates bonded and bonding process D and the manufacturing method of a separator for a fuel cell stack comprising a that joins 8,8 the sandwich.

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