JP2006179402A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell allowing fastening of a laminate of unit cells not to apply an excessive load to a power generating part, while securing excellent sealability in its seal part. <P>SOLUTION: This fuel cell is composed by laminating and fastening a plurality of the unit cells 10. This structure has fastening load applying mechanisms (21, 22, 23a, 23b, 24a, 24b, 24c, 24d, 25, 26) to apply different fastening loads to the power generating part and the sealing part in the laminate of a plurality of the unit cells 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell having a structure in which a plurality of single cells are stacked and fastened.

  For example, a polymer electrolyte fuel cell has a structure in which a plurality of single cells, which are units of a battery, are stacked, and the plurality of stacked single cells are fastened. Each single cell basically includes a membrane / electrode assembly (hereinafter referred to as MEA (Membrane Electrode Assembly) including an electrolyte membrane, a pair of catalyst layers sandwiching the electrolyte membrane, and a pair of diffusion layers positioned outside each catalyst layer. )) Is sandwiched between a pair of separators. In a fuel cell having such a structure, conventionally, a plurality of single cells are fastened as follows (see, for example, Patent Document 1).

  The lower holder and the plate-like pressing member are connected to each other with a predetermined distance by a plurality of rods, and a plurality of single cells are stacked between the lower holder and the upper holder positioned inside the pressing member. The tips of a plurality of adjustment bolts screwed to the holding member are in contact with the upper holder, and the upper holder is pressed toward the lower holder by tightening each adjustment bolt, so that the gap between the upper holder and the lower holder is reduced. A plurality of single cells stacked on each other are fastened.

In a conventional fuel cell having such a structure, it is possible to fasten a plurality of stacked single cells with a uniform fastening load by appropriately adjusting the tightening torque of the adjusting bolt.
JP 2000-208163 A

  By the way, as described above, each single cell has the MEA and two separators sandwiching the MEA, and the outer peripheral portions of the two separators are sealed with, for example, an adhesive. Further, the outer peripheral portions of adjacent single cells are also sealed with, for example, silicon rubber. Thus, the outer peripheral part of the laminated body (stack) of a plurality of single cells is a seal part, and the inner side of the outer peripheral part is a power generation part that substantially includes the MEA and generates power.

  In order to improve the sealing performance at the seal portion, it is preferable to fasten a plurality of stacked single cells with as large a fastening load as possible. On the other hand, since the MEA included in the power generation unit is composed of a thin film, when a plurality of stacked single cells are fastened with an excessive fastening load, the MEA collapses or the MEA is formed in the gas flow path formed in the separator. If it protrudes, problems such as a decrease in performance and durability of the fuel cell occur.

  In a conventional fuel cell in which a plurality of stacked single cells are fastened with a uniform fastening load, if the fastening load is suitable for a seal portion, the fastening load is not applied to the MEA (power generation portion). There is a possibility that the problems described above may occur due to being too large. On the other hand, if the fastening load is suitable for MEA, conversely, the sealing performance at the seal portion may not be sufficiently secured.

  The present invention has been made to solve such a conventional problem, and a single-cell laminate is formed so that an excessive load is not applied to the power generation unit while ensuring good sealing performance at the seal unit. A fuel cell that can be fastened is provided.

  The fuel cell according to the present invention is a fuel cell having a structure in which a plurality of single cells are stacked and fastened, and different fastening loads are applied to the power generation section and the seal section in the stack of the plurality of single cells. It becomes the structure which has a fastening load provision mechanism.

  With such a configuration, in a state where the fastening load applied to the power generation unit in the laminated body of single cells is different from the fastening load applied to the seal part in the laminated body, the laminated body of the single cells It is concluded. For this reason, it becomes possible to apply an appropriate fastening load to both the power generation section and the seal section in the single cell laminate.

  The power generation unit refers to a portion that substantially generates power by a reaction between a fuel gas (hydrogen-containing gas) and an oxidant gas (oxygen-containing gas) in the presence of water in a single cell laminate. Further, the seal portion refers to a portion where a seal is applied without performing practical power generation in a single cell laminate.

  In the fuel cell according to the present invention, the fastening weight applying means includes a first partial fastening load applying mechanism that applies a fastening load to the seal portion, and a second that applies a fastening load to the power generation portion. It can be set as the structure which has a partial fastening load provision mechanism.

  With such a configuration, different fastening loads can be applied to the seal portion and the power generation portion in the single cell laminate.

  Further, in the fuel cell according to the present invention, the first partial fastening load applying mechanism includes a first plate body and a second plate body that sandwich the stacked body of the plurality of single cells, and the first plate body and At least one of the second plate bodies is in contact with an outer peripheral portion corresponding to the seal portion of the end single cell without contacting a portion corresponding to the power generation portion of the end single cell in the stacked body, It can be set as the structure which has a fastening mechanism which fastens 1 plate and the said 2nd plate with a predetermined fastening load.

  With such a configuration, when the tightening mechanism tightens the first plate body and the second plate body with a predetermined fastening load, the predetermined fastening load is applied to the seal portion in the single cell laminate. .

  Furthermore, the fuel cell according to the present invention may be configured such that the tightening mechanism includes means for regulating a distance between the first plate body and the second plate pair to a predetermined value.

  With such a configuration, a fastening load according to the distance between the first plate body and the second plate body, which is regulated to a predetermined value, is a plurality of single units sandwiched between the first plate body and the second plate body. Added to the seal for each of the cells.

  Further, in the fuel cell according to the present invention, the second partial fastening load applying mechanism corresponds to the power generation unit of the end single cell in which at least one of the first plate body and the second plate body does not contact. It can be set as the structure which provides a fastening load with respect to the performed site | part.

  With such a configuration, a fastening load is applied from the second partial fastening load applying mechanism to the power generation unit in the stacked body of a plurality of single cells sandwiched between the first plate body and the second plate body.

  In the fuel cell according to the present invention, the second partial fastening load applying mechanism may have an adjustment mechanism for adjusting the fastening load.

  With such a configuration, it is possible to adjust the fastening load on the power generation unit in the single cell stack.

  According to the fuel cell of the present invention, the single cell in a state where the fastening load applied to the power generation unit in the stacked body of single cells is different from the fastening load applied to the seal portion in the stacked body. Therefore, an appropriate fastening load can be applied to both the power generation section and the seal section in the single cell stack. As a result, it is possible to fasten a laminate of a plurality of single cells so that an excessive load is not applied to the power generation unit while ensuring good sealing performance at the seal unit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The fuel cell according to the first embodiment of the present invention is configured as shown in FIG.

  In FIG. 1, this fuel cell has a structure in which a stacked body (stack) of a plurality of single cells 10 is sandwiched between a pair of end plates 21 and 22 (first plate body, second plate body). One end plate 21 has a substantially flat plate shape, and the entire end surface of the unit cell 10 (end unit cell) located at one end of the stacked body of unit cells 10 is in contact with the end plate 21. The other end plate 22 includes a cup portion 22b having a concave portion 22c formed at the center and a flange portion 22a protruding outward from the outer periphery of the cup portion 22b. Then, the outer peripheral portion of the single cell 10 (end single cell) located at the other end of the laminated body of the single cells 10 hits a predetermined portion that continues from the edge of the cup portion 22b of the end plate 22 to the flange portion 22a. It touches.

  A spring box 25 is accommodated in a recess 22c formed in the cup portion 22b of the end plate 22, and the pressure applied to the spring box 25 is adjusted by a load adjuster 26 attached to the cup portion 22b. A predetermined portion inside the outer peripheral portion of the single cell 10 positioned at the other end of the stacked body of the single cells 10 is in contact with the spring box 25.

  Four corners of the end plate 21 and four corners of the flange portion 22a of the end plate 22 are connected by through bolts 23a and 23b (only two are shown in the drawing), and are nuts that are screwed into both ends of the through bolts 23a and 23b. The end plate 21 and the end plate 22 are fastened by 24a, 24b, 24c, and 24d (tightening mechanism).

  A more detailed structure will be described with reference to FIG. 2 showing the detailed structure of the A part in FIG.

  In FIG. 2, each of the stacked unit cells 10 includes an MEA (Membrane Electrode Assembly) 11 including an electrolyte membrane, a pair of catalyst layers sandwiching the electrolyte membrane, and a pair of diffusion layers positioned outside each catalyst layer. The structure is sandwiched between a pair of separators 12 and 13. Each separator 12 and 13 becomes uneven | corrugated in cross section, and the gas flow path and the water flow path are formed. An outer peripheral part of the single cell 10 in which the gas flow path or the like of the pair of separators 12 and 13 is not formed is bonded with an adhesive 14, thereby sealing the outer peripheral part. Further, the outer peripheral portions of the adjacent single cells 10 are sealed with a gasket seal 15 such as silicon rubber. Thus, the outer peripheral part of the laminated body of the several single cell 10 becomes the seal | sticker part 100a (The adhesive agent 14 and the gasket seal | sticker 15 are included.). And in the laminated body of the single cell 10, the electric power generation part 100b used as the site | part by which MEA11 produces electric power substantially is located inside the seal | sticker part 100a.

The predetermined part E following the flange part 22a from the end edge part of the cup part 22b of the end plate 22 is in contact with the outer peripheral part of the end unit cell corresponding to the seal part 100a in the laminated body of the unit cells 10. . Further, the spring box 25 is in contact with a predetermined portion of the end unit cell corresponding to the power generation unit 100 b in the stacked body of the unit cells 10.
The

  In the fuel cell having such a structure, the end plates 21 and 22 are fastened by nuts 24a, 24b, 24c and 24d attached to both ends of the through bolts 23a and 23b, whereby the end plate 21 and the end plate 22 are predetermined. A plurality of single cells 10 sandwiched between the parts E are fastened. Then, a fastening load generated by tightening each nut is applied to the seal portion 100a in the laminated body of the single cells 10, and the seal portion 100a is compressed. The fastening load applied to the predetermined number (plurality) of single cells 10 corresponds to the distance L between the end plate 21 and the flange portion 22 a of the end plate 22. Therefore, the end plate by the nut is set so that the distance L between the end plate 21 and the flange portion 22a of the end plate 22 corresponds to a fastening load that can secure a sufficient sealing performance at the seal portion 100a. 21 and 22 are tightened.

  Thus, in the state where the fastening load is applied to the seal portion 100a in the laminated body of the single cells 10, for example, the fastening load is not applied to the power generation portion 100b in the laminated body, or a slight fastening is performed. The dimensions of the gasket seal 15 and the thicknesses of the separators 12 and 13 are set so that only a load is applied.

  In this state, the applied pressure of the spring box 25 is adjusted by the load adjuster 16, and a fastening load corresponding to the applied pressure is applied from the spring box 25 to the power generation unit 100 b in the stacked body of the single cells 10. The fastening load applied to the power generation unit 100b is within a range in which the MEA 11 (thin film) included in the power generation unit 100b is not crushed, and the MEA 11 does not protrude into the gas flow paths formed in the separators 12 and 13, etc. Set to

  Thus, in the fuel cell according to the first embodiment of the present invention, by tightening the end plates 21 and 22 by the nuts 24a, 24b, 24c and 24d attached to both ends of the through bolts 23a and 23b, A fastening load that can satisfactorily maintain the sealing performance can be applied to the seal portion 100a in the laminate of the single cells 10. In addition, the spring box 25 whose pressure is adjusted by the load adjuster 26 can apply an appropriate fastening load that does not impair the power generation action to the power generation unit 100b in the stacked body of the single cells 10.

  Next, a fuel cell according to a second embodiment of the present invention will be described.

  The basic structure of the fuel cell according to the second embodiment is the same as that shown in FIG. 1, but a mechanism for applying a fastening load to the seal portion 100a in the laminate of the single cells 10 is shown in FIG. ) Is different from what is shown.

  In the fuel cell according to the second embodiment, as shown in FIG. 3, the end plate 22 includes a cup portion 22b having a recess 22c formed in the center, and a flange portion 22d protruding inward from the outer periphery of the cup portion 22b. It is composed of The pressing plate 27 is disposed so as to be in contact with the outer surface of the flange portion 22d, and the distal end portion of the pressing plate 27 is in contact with the outer peripheral portion of the end single cell corresponding to the seal portion 100a in the stacked body of the single cells 10. Yes. The through bolts 23a and 23b pass through the pressing plate 27 and the flange portion 22d of the end plate 22, and each through bolt 23a (23b) enters the recess 22c of the cup portion 22b from the flange portion 22d of the end plate 22. The nuts 24a and (24c) are attached to the tip of the bracket.

  In the fuel cell having such a structure, the single cell 10 is interposed via the pressing plate 27 by tightening the end plates 21 and 22 with nuts 24a, 24b, 24c and 24d attached to both ends of the through bolts 23a and 24a. A fastening load is applied to the seal portion 100a in the laminate. In this case, the end plate 21 made of the nut is used so that the distance L between the end plate 21 and the pressing plate 27 corresponds to a fastening load that can sufficiently secure the sealing performance at the seal portion 100a. 22 is tightened.

  Next, a fuel cell according to a third embodiment of the present invention will be described.

  The basic structure of the fuel cell according to the third embodiment is the same as that shown in FIG. 1, but the structure of the through bolts 23a and 23b is different from that shown in FIG. 1 (FIG. 2).

  In the fuel cell according to the third embodiment, as shown in FIG. 4, the end plates 21 and 22 are connected by stepped through bolts 23a (23b). The stepped through bolt 23a has a large diameter portion having a length L and small diameter portions formed at both ends of the large diameter portion, and a step 230 is formed at the boundary between the large diameter portion and the small diameter portion. The through hole of the stepped through bolt 23a formed in each of the flange portion 22a of the end plate 22 and the end plate 21 (not shown) matches the diameter of the small diameter portion.

  In such a fuel cell, the end plate 21 and the end plate 22 are fastened to each other by tightening the end plate 21 and the flange portion 22a of the end plate 22 with nuts 24a, 24b, 24c, and 24d attached to both ends of the stepped bolts 23a and 23b. The distance from the flange portion 22a of the plate 22 is regulated to a distance L corresponding to the length of the large diameter portion of the stepped through bolt 23a. As a result, a fastening load corresponding to the distance L between the end plate 21 and the flange portion 22 a of the end plate 22 is applied to the seal portion 100 a in the stacked body of the single cells 10.

  In this case, the length of the large-diameter portion of each stepped through bolt 23a, 23b is such that the end plate 21 and the flange portion 22a of the end plate 22 correspond to a fastening load sufficient to ensure sufficient sealing performance at the seal portion 100a. Is set to a value corresponding to the distance L between the nuts 24a, 24b, 24c, and 24d without measuring the distance between the end plate 21 and the flange portion 22a of the end plate 22 and tightening the nuts 24a, 24b, 24c, and 24d. However, by simply tightening each nut to the maximum, the distance between the end plate 21 and the flange portion 22a of the end plate 22 is automatically regulated to the distance L, and the seal portion 100a can be sufficiently secured. A correct fastening load is applied.

  Next, a fuel cell according to a fourth embodiment of the present invention will be described.

  The basic structure of the fuel cell according to the fourth embodiment is the same as that shown in FIG. 1 except that a cylindrical or prismatic angle member is used instead of the through bolts 23a and 23b. Different from the first and third embodiments.

  As shown in FIG. 5, in the fuel cell according to the fourth embodiment, the end plates 21 and 22 are connected by angle members 28a (28b). Screw holes are formed in both end faces of the angle member 28a (28b). The screws 29a (29b) are screwed into the screw holes formed on both end faces of the angle member 28a (28b) through the flange portion 22a of the end plate 22 and the through holes formed in the end plate 21. By tightening the flange portion 22a, the length between the end plate 21 and the end plate 22 is regulated by the length of the angle member 28a. As a result, a fastening load corresponding to the distance between the end plate 21 and the flange portion 22 a of the end plate 22 is applied to the seal portion 100 a in the stacked body of the single cells 10.

  In this case, the length of the angle member 28a (28b) is set to a distance L between the end plate 21 and the flange portion 22a of the end plate 22 corresponding to a fastening load that can sufficiently secure the sealing performance at the seal portion 100a. By setting the corresponding values, the screws 29a (29b) are simply screwed into the angle members 28a (28b) as much as possible to automatically connect the end plate 21 and the flange portion 22a of the end plate 22 to each other. The distance is restricted to the distance L, and an appropriate fastening load that can sufficiently secure the sealing performance is applied to the seal portion 100a.

  Next, a fuel cell according to a fifth embodiment of the invention will be described.

  The basic structure of the fuel cell according to the fourth embodiment is the same as that shown in FIG. 1 except that a plate material is used instead of the through bolts 23a and 23b as described above. Different from the first and third embodiments.

  In the fuel cell according to the fifth embodiment, as shown in FIG. 6, the end plates 21 and 22 are connected by a plate material 30a (30b). Step portions 300 are formed at both ends of the plate material 30a (30b). Each step portion 300 of the plate material 30a (30b) is engaged with an end portion of the flange portion 22a of the end plate 22 and an end portion (not shown) of the end plate 21. Then, one end of the plate material 30a (30b) and the end of the flange portion 22a of the end plate 22 are screwed with screws 31a, and the other end of the plate material 30a (30b) and the end of the end plate 21 are connected. Screwed with a screw (31b). Thereby, the distance between the end plate 21 and the end plate 22 is regulated by the length between the step portions 300 of the plate material 30a (30b), and corresponds to the distance between the end plate 21 and the flange portion 22a of the end plate 22. The fastening load thus applied is applied to the seal portion 100a in the laminated body of the single cells 10.

In this case, the length between the step portions 300 of the plate material 30a (30b) is set between the end plate 21 and the flange portion 22a of the end plate 22 corresponding to a fastening load that can ensure a sufficient sealing performance at the seal portion 100a. By setting the value corresponding to the distance L between them, the plate material 30a (30b) is simply screwed to the flange portion 22a of the end plate 21 and the end plate 22 by each screw 31a (31b), The distance between the end plate 21 and the flange portion 22a of the end plate 22 is automatically regulated to the distance L, and an appropriate fastening load that can sufficiently secure the sealing performance is applied to the seal portion 100a.
The fastening load can be restricted only by the length of the plate members 30a and 30b.

  Next, a fuel cell according to a sixth embodiment of the present invention will be described.

  The fuel cell according to the sixth embodiment is the fuel according to each embodiment described above in that a fastening load is applied to the seal portion 100a in the stacked body of the single cells 10a by a spring box in the same manner as the power generation portion 100b. Different from battery.

  The fuel cell according to the sixth embodiment is configured as shown in FIG.

  In FIG. 7, this fuel cell has a structure in which a stack of a plurality of single cells 10 is sandwiched between a pair of end plates 21 and 22. The entire end surface of the end unit cell on one side of the stacked body of the unit cells 10 is in contact with the end plate 21. A ring-shaped spring box 32 between the end plate 22 and the outer peripheral portion (corresponding to the seal portion 100a (see FIGS. 2 to 6)) of the end single cell located on the other end side of the stacked body of the single cells 10. Is arranged. In addition, a predetermined portion inside the outer peripheral portion of the end single cell located on the other end side of the stacked body of the single cells 10 is in contact with the spring box 25. As in the case shown in FIG. 1, the end plates 21 and 22 are connected by through bolts 23a and 23b, and are fastened by nuts 24a, 24b, 24c and 24d attached to both ends of the through bolts 23a and 23b. .

  In the fuel cell having such a structure, a fastening load corresponding to the pressurizing force generated in the spring box 32 is applied to the outer peripheral portion corresponding to the seal portion in the stacked body of the single cells 10. A fastening load corresponding to the applied pressure generated by the spring box 25 adjusted by the load adjuster 26 is applied to a predetermined portion inside the outer peripheral portion corresponding to the power generation unit. Accordingly, by appropriately setting the pressure generated in the spring box 32 and adjusting the pressure generated in the spring box 25 or appropriately by the load adjuster 26, In addition to applying a fastening load that can maintain the sealing performance well, an appropriate fastening load that does not impair the power generation action can be applied to the power generation section in the stacked body of the single cells 10.

In the first to fifth embodiments described above (see FIGS. 1 to 6), the spring box 25 is arranged on one end plate 22 side. The end plate 21 can have the same structure as the end plate 22, and a spring box can also be arranged on the end plate 21 side.
The embodiments of the present invention have been described above. The mechanism for applying the fastening load is not limited to the spring box, and may be an elastic resin (rubber or the like).

  As described above, the fuel cell according to the present invention can fasten a single-cell stack so that an excessive load is not applied to the power generation unit while ensuring good sealing performance at the seal unit. Therefore, it is useful as a fuel cell having a structure in which a plurality of single cells are stacked and fastened.

It is a figure which shows the fuel cell which concerns on 1st embodiment of this invention. It is a figure which shows the A section detailed structure in FIG. It is a figure which shows the partial detailed structure of the fuel cell which concerns on 2nd embodiment of this invention. It is a figure which shows the partial detailed structure of the fuel cell which concerns on 3rd embodiment of this invention. It is a figure which shows the partial detailed structure of the fuel cell which concerns on 4th embodiment of this invention. It is a figure which shows the partial detailed structure of the fuel cell which concerns on 5th embodiment of this invention. It is a figure which shows the fuel cell which concerns on the 6th Embodiment of this invention.

Explanation of symbols

10 Single cell 11 Membrane / electrode assembly (MEA)
12, 13 Separator 14 Adhesive layer 15 Gasket seal 21, 22 End plate 22a Flange 22b Cup 22c Recess 23a, 23b Through bolt (stepped through bolt)
24a, 24b, 24c, 24d Nut 25 Spring box 26 Load adjuster 27 Pushing plate 28a Angle material 29a, 31a Screw 30a Plate material 32 Spring box 100a Seal part 100b Power generation part

Claims (6)

A fuel cell having a structure in which a plurality of single cells are stacked and fastened,
A fuel cell, comprising: a fastening load applying mechanism that applies different fastening loads to the power generation section and the seal section in the laminate of the plurality of single cells. The fastening weight applying means includes a first partial fastening load applying mechanism that applies a fastening load to the seal portion;
The fuel cell according to claim 1, further comprising a second partial fastening load applying mechanism that applies a fastening load to the power generation unit.   The first partial fastening load applying mechanism includes a first plate body and a second plate body that sandwich the stacked body of the plurality of single cells, and at least one of the first plate body and the second plate body includes the first plate body and the second plate body. Without contacting the portion corresponding to the power generation part of the end single cell in the laminated body, it contacts the outer peripheral part corresponding to the seal part of the end single cell, and the first plate and the second plate are connected to each other. The fuel cell according to claim 2, further comprising a tightening mechanism for tightening with a tightening load.   4. The fuel cell according to claim 3, wherein the tightening mechanism has means for restricting a distance between the first plate body and the second plate body to a predetermined value.   The second partial fastening load applying mechanism applies a fastening load to a portion corresponding to the power generation portion of the end unit cell where at least one of the first plate body and the second plate body does not contact. The fuel cell according to claim 3 or 4, wherein 5. The fuel cell according to claim 2, wherein the second partial fastening load application mechanism includes an adjustment mechanism that adjusts the fastening load. 6.

Images