JP2018129214A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack that suppresses gaps between unit cells due to thickness tolerance of resin frames.SOLUTION: In a fuel cell stack in which a plurality of single cells 140 and a gasket GK5 sandwiched between any two adjacent single cells are stacked, a peripheral edge portion 31R of a resin frame 31 extends outward beyond the outer periphery of a first separator 50, and on the first surface of the resin frame, the peripheral edge portion of the resin frame has a plurality of first protrusions 34 protruding in the stacking direction of the unit cells, and on the second surface of the resin frame, the peripheral edge portion of the resin frame has a second protrusion 35 protruding in the stacking direction at a position between the two adjacent first protrusions, and an outer peripheral portion 42 of a second separator 40 is pressed by the plurality of first protrusions of one of the two adjacent single cells and the second protrusion of the other single cell.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel cell stack.

  Patent Document 1 discloses a fuel cell stack in which a plurality of single cells are stacked. Between two adjacent single cells, a gasket for preventing leakage of reaction gas and cooling medium flowing through each single cell is disposed. The gasket is formed separately from the single cell separator and is disposed on the separator, and seals between the two single cells by pressing the two adjacent single cells.

JP 2006-004851 A

  In general, a single cell has a membrane electrode gas diffusion layer assembly (hereinafter referred to as “MEGA”) and a MEGA plate having a resin frame joined around the MEGA. That is, it is configured by being sandwiched between the anode side separator and the cathode side separator. The gasket is disposed in a region overlapping the resin frame in the stacking direction.

  There is tolerance in the thickness of the resin frame of a single cell. When stacking a plurality of single cells, if the tolerance of the thickness of the resin frame is stacked, there is a problem that a large gap is generated between the single cells and the gasket protrudes to the outside.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, there is provided a fuel cell stack in which a plurality of single cells and a gasket sandwiched between any two adjacent single cells are stacked. In the fuel cell stack, the single cell includes a membrane electrode gas diffusion layer assembly, a resin frame bonded around the membrane electrode gas diffusion layer assembly, and a first separator in contact with the first surface of the resin frame. And a second separator in contact with the second surface of the resin frame. The gasket is disposed between the first separator and the second separator, and at least a part of the gasket runs along the outer periphery of the first separator, and the peripheral portion of the resin frame is formed on the first separator. The resin frame extends outward from the outer periphery, and on the first surface of the resin frame, the peripheral portion of the resin frame has a plurality of first protrusions protruding in the stacking direction of the single cells, and the resin In the second surface of the frame, the peripheral portion of the resin frame has a second protrusion protruding in the stacking direction at a position between two adjacent first protrusions, and the second separator. The outer peripheral portion is pressed by the plurality of first convex portions of one of the two single cells and the second convex portion of the other single cell.
According to the fuel cell stack of this embodiment, the outer peripheral portion of the second separator is pressed by the plurality of first convex portions of one single cell and the second convex portion of the other single cell among two adjacent single cells. Therefore, the outer peripheral portion of the second separator functions as a spring structure. As a result, even when the tolerance of the thickness of the resin frame is piled up, it is possible to suppress a large gap between adjacent resin frames due to the repulsive force of the outer peripheral portion of the second separator, and the gasket pops out to the outside. Can be suppressed.

  The present invention can be implemented in various forms other than the above. For example, it can be realized in the form of a fuel cell stack manufacturing method, a fuel cell single cell, a fuel cell resin frame, or the like.

The disassembled perspective view of the fuel cell stack in one Embodiment of this invention. The schematic of the fuel cell stack seen from the anode side separator side. The perspective view of a part of fuel cell stack. Sectional drawing of a part of fuel cell stack. Sectional drawing of a part of fuel cell stack. The side view of a fuel cell stack. The side view of a fuel cell stack. FIG. 4 is a cross-sectional view of a part of the fuel cell stack in Reference Example 1. FIG. 4 is a cross-sectional view of a part of the fuel cell stack in Reference Example 1. FIG. 4 is a partial cross-sectional view of a fuel cell stack in Reference Example 2. FIG. 4 is a partial cross-sectional view of a fuel cell stack in Reference Example 2.

  FIG. 1 is an exploded perspective view of a fuel cell stack 100 according to an embodiment of the present invention. The fuel cell stack 100 is formed by stacking a plurality of single cells 140 in the Z-axis direction shown in FIG. In the figure, the Z axis and the X axis are parallel to the horizontal plane, the + Y direction indicates a vertically upward direction, and the −Y direction indicates a vertically downward direction. The single cell 140 includes a MEGA plate 30 having a MEGA 32 and a resin frame 31 bonded around the MEGA 32, and two separators 40 and 50 arranged with the MEGA plate 30 interposed therebetween, that is, an anode-side separator 50 (first Separator) and a cathode-side separator 40 (second separator). The fuel cell stack 100 is a so-called polymer electrolyte fuel cell, and constitutes a fuel cell system together with a reaction gas (oxidant gas and fuel gas) supply unit, a cooling medium supply unit, and the like. Such a fuel cell system is mounted on a vehicle or the like as a system for supplying driving power, for example.

  FIG. 2 is a schematic view of the fuel cell stack 100 as viewed along the + Z direction from the surface of the anode-side separator 50. For convenience of illustration, the peripheral portion 31R of the resin frame 31 of the MEGA plate 30 (FIG. 1) is hatched. A peripheral portion 31 </ b> R of the resin frame 31 extends outward from the outer periphery of the anode separator 50. A peripheral convex portion 33 is formed on the peripheral portion 31 </ b> R so as to surround the outer periphery of the anode separator 50. The peripheral convex portion 33 has a rectangular shape in plan view shown in FIG. However, the peripheral convex portion 33 may be omitted.

  A fuel gas inlet manifold hole 62, a cooling medium outlet manifold hole 84, and an oxidant gas inlet manifold hole 72 are arranged in this order from the top to the bottom at one end edge in the longitudinal direction of the anode separator 50. ing. On the other hand, an oxidant gas outlet manifold hole 74, a cooling medium inlet manifold hole 82, and a fuel gas outlet manifold hole 64 are provided in order from the top to the bottom at the other end edge. . A plurality of streaky coolant passage grooves 54 are formed in the central portion of the anode-side separator 50. For the separators 40 and 50, for example, a press-formed plate obtained by press-forming a metal member such as stainless steel or titanium is employed. However, in addition to the press-formed plate, a separator having elasticity, conductivity, and gas impermeability may be used.

  Of the fuel gas supplied from the fuel gas inlet manifold hole 62, the unused fuel gas is collected by the fuel gas outlet manifold hole 64 and discharged to the outside of the fuel cell stack 100 (FIG. 1). Of the oxidant gas supplied from the oxidant gas inlet manifold hole 72, the oxidant gas that has not been used is collected by the oxidant gas outlet manifold hole 74 and discharged to the outside of the fuel cell stack 100. Further, the cooling medium supplied from the cooling medium inlet manifold hole 82 flows through the cooling medium flow channel groove 54, is collected by the cooling medium outlet manifold hole 84, and is discharged to the outside of the fuel cell stack 100.

  In FIG. 2, gaskets GK <b> 1 to GK <b> 4 are arranged on the surface of the anode separator 50 so as to surround the reaction gas manifold holes 62, 64, 72, and 74. Further, a gasket GK5 is disposed so as to surround the cooling medium manifold holes 82 and 84 and the cooling medium flow channel 54. The portion closest to the outer periphery of the anode separator 50 of each of the gaskets GK1 to GK5 is running in parallel with the outer periphery of the anode separator 50.

  The gaskets GK <b> 1 to GK <b> 5 have a function of contacting the surface of two adjacent single cells 140 when the plurality of single cells 140 are stacked, and sealing between the two single cells 140. Specifically, the gaskets GK1 and GK2 are for preventing leakage of fuel gas, the gaskets GK3 and GK4 are for preventing leakage of oxidant gas, and the gasket GK5 is for leakage of cooling medium. It is for preventing. These gaskets GK <b> 1 to GK <b> 5 are formed separately from the anode-side separator 50 and are sandwiched between two adjacent single cells 140. As the gaskets GK1 to GK5, for example, soft gaskets including elastic members such as rubber and resin can be used. In addition, it is preferable that these gaskets GK1 to GK5 have non-adhesiveness.

  FIG. 3 is an enlarged perspective view of a range III surrounded by a broken line shown in FIG. 2, and is a view before a plurality of single cells 140 are tightened. For convenience of illustration, only two single cells 140 are shown, and the gasket GK5 is hatched. Moreover, the cross-sectional shape of the gasket GK5 is simplified. In FIG. 3, the anode side separator 50 is in contact with the first surface S1 (upper surface) of the resin frame 31 of the single cell 140, and the cathode side separator 40 is connected to the second surface S2 (lower surface) of the resin frame 31 of the single cell 140. It touches. The gasket GK5 is running in parallel with the outer periphery of the anode side separator 50.

  In FIG. 3, on the first surface S <b> 1 of the resin frame 31, one peripheral convex portion 33 and two first convex portions 34 that are integrally formed with the peripheral portion 31 </ b> R of the resin frame 31 and extend in a line shape are formed. Yes. The peripheral convex portion 33 surrounds the outer periphery of the anode-side separator 50, extends in the Y direction, and protrudes in the stacking direction (−Z direction). The first convex portion 34 is formed integrally with the peripheral convex portion 33 at a position outside the peripheral convex portion 33, extends in the X direction, and protrudes in the stacking direction (−Z direction). Note that three or more first protrusions 34 may be formed.

  On the second surface S <b> 2 of the resin frame 31, the peripheral portion 31 </ b> R of the resin frame 31 has a streaky second convex portion 35. The second convex portion 35 is formed integrally with the peripheral portion 31R, and protrudes in the stacking direction (+ Z direction) at a position between two adjacent first convex portions 34. In addition, the 1st convex part 34 and the 2nd convex part 35 may have another shape (for example, cylindrical shape) instead of a streak shape. Moreover, the peripheral convex part 33, the 1st convex part 34, and the 2nd convex part 35 may not be formed integrally with the peripheral part 31R, but may be formed separately and adhered to the peripheral part 31R.

  The outer peripheral portion 42 of the cathode side separator 40 extends outward from the outer periphery of the anode side separator 50 and has a step portion 41. The step portion 41 forms a gap G <b> 1 between the cathode separator 40 and the peripheral portion 31 </ b> R of the resin frame 31. In the gap G1, the second convex portion 35 of the peripheral edge portion 31R is formed.

  FIG. 4 is an explanatory diagram of a cross section IV that passes through the center of the second convex portion 35 shown in FIG. 3. The second convex portion 35 of the resin frame 31 is in contact with the outer peripheral portion 42 of the cathode side separator 40. The step portion 41 of the outer peripheral portion 42 is slightly in contact with the peripheral convex portion 33 of the resin frame 31 of another adjacent unit cell 140. When the plurality of single cells 140 are tightened, the stepped portion 41 is pressed by the peripheral convex portion 33. Moreover, the peripheral convex part 33 is aligned in the lamination direction, and has a function of suppressing the gasket GK5 from jumping out.

  FIG. 5 is an explanatory diagram of a cross section V that passes through the center of the first convex portion 34 shown in FIG. 3. The first convex portion 34 of the resin frame 31 is in contact with the outer peripheral portion 42 of the cathode separator 40 of another adjacent unit cell 140.

  FIG. 6 is a side view of the plurality of single cells 140 shown in FIG. 3 as viewed along the −X direction. For convenience of illustration, the cathode separator 40 of the lower unit cell 140 is omitted. For convenience of explanation, “u” is attached to the reference numeral of the upper unit cell 140, and “d” is attached to the lower part of the unit cell 140.

  In FIG. 6, the outer peripheral portion 42u of the cathode separator 40u of the single cell 140u is in contact with the two first protrusions 34d of the single cell 140d, and a gap G2 is formed between the resin frame 31d. The second convex portion 35u of the single cell 140u is in contact with the outer peripheral portion 42u of the cathode side separator 40u at a position between the two first convex portions 34d of the single cell 140d. Further, a gap G1 is formed between the outer peripheral portion 42u and the resin frame 31u of the single cell 140u.

  FIG. 7 is a diagram showing how the single cells 140u and 140d of FIG. 6 are tightened. When the single cells 140u and 140d are tightened, the outer peripheral portion 42u of the cathode separator 40u is pressed by the two first convex portions 34d of the single cell 140d and the second convex portion 35u of the single cell 140u. As a result, the portion of the outer peripheral portion 42u that is in contact with the second convex portion 35u is curved toward the single cell 140d, and the gaps G1 and G2 are reduced. Here, since the cathode-side separator 40u has elasticity, even if the sizes of the gaps G1 and G2 slightly change, they can be absorbed by spring elasticity. In this way, the tolerance of the thickness of the resin frames 31u and 31d can be compensated by the size of the gaps G1 and G2, and the tolerances are stacked to create a large gap between the adjacent resin frames 31u and 31d, thereby causing the gasket GK5. Can be prevented from jumping out.

  As described above, in the embodiment, the two first protrusions 34d of one unit cell 140d and the other unit cell of two unit cells 140u and 140d adjacent to each other on the outer peripheral portion 42 of the cathode-side separator 40. Since it is pressed by the 140u 2nd convex part 35u, the outer peripheral part 42 of the cathode side separator 40 acts as a spring structure. As a result, even when the thickness tolerances of the resin frames 31u and 31d are stacked, it is possible to prevent a large gap from being generated between the adjacent resin frames 31u and 31d due to the repulsive force of the outer peripheral portion 42 of the cathode separator 40. It is possible to suppress the gasket GK5 from jumping out.

Reference example 1:
FIG. 8 is a cross-sectional view of the plurality of single cells 140a in Reference Example 1, and corresponds to FIG. In FIG. 8, the resin frame 31 a does not have the first convex portion 34 and the second convex portion 35.
The peripheral convex portion 33a of the resin frame 31a is formed of an elastic material such as an elastomer. The cathode side separator 40a does not have an outer peripheral portion and is adjacent to the peripheral convex portion 33a.

  FIG. 9 is a diagram showing how the plurality of single cells 140a in FIG. 8 are fastened. The peripheral convex portion 33a of the resin frame 31a is pressed and deformed by the adjacent cathode side separator 40a. In Reference Example 1, the repulsive force of the peripheral convex portion 33a can suppress the occurrence of a large gap between adjacent resin frames 31a due to the thickness tolerances of the resin frames 31a being stacked, and the gasket GK5 can be prevented from popping outward. Can be suppressed.

Reference example 2:
FIG. 10 is a cross-sectional view of the plurality of single cells 140b in Reference Example 2, and corresponds to FIG. 10, the peripheral convex portion 33b of the resin frame 31b is formed of the same material as the resin frame 31b, and is smaller in size than the peripheral convex portion 33a of FIG. An attached elastic portion GK51 having elasticity is integrally formed with the gasket GK5b. The attached elastic part GK51 is arranged between the cathode side separator 40a and the adjacent peripheral convex part 33b. Note that it is also possible to consider the entire attached elastic portion GK51 and the peripheral convex portion 33b as one “convex portion”.

  FIG. 11 is a diagram illustrating a state in which the plurality of single cells 140b in FIG. 10 are fastened. The attached elastic part GK51 of the gasket GK5b is pressed and deformed by the peripheral convex part 33b adjacent to the cathode side separator 40a. In Reference Example 2, the repulsive force of the attached elastic portion GK51 can suppress the occurrence of a large gap between adjacent resin frames 31b due to the thickness tolerances of the resin frames 31b being stacked, and the gasket GK5b can be prevented from popping outward. Can be suppressed.

  As can be understood from the above description, Reference Example 1 and Reference Example 2 are common in that at least a part of the convex portion running on the outer periphery of the first separator is formed of an elastic member. Due to the repulsive force of the elastic material, it is possible to suppress the tolerances of the thickness of the resin frames from being accumulated and to generate a large gap between the adjacent resin frames, and it is possible to suppress the gasket from jumping to the outside.

・ Modification:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

・ Modification 1:
In the above embodiment, the anode side separator 50 is the first separator and the cathode side separator 40 is the second separator. However, the cathode side separator may be the first separator and the anode side separator may be the second separator.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 30 ... MEGA plate 31, 31a, 31b, 31u, 31d ... Resin frame 31R ... Peripheral part 32 ... Membrane electrode gas diffusion layer assembly (MEGA)
33, 33a, 33b ... Peripheral convex part 34, 34d ... First convex part 35, 35u ... Second convex part 40, 40a, 40u ... Cathode side separator 41 ... Step part 42, 42u ... Peripheral part 50 ... Anode side separator 54 ... Cooling medium passage groove 62 ... Fuel gas inlet manifold hole 64 ... Fuel gas outlet manifold hole 72 ... Oxidant gas inlet manifold hole 74 ... Oxidant gas outlet manifold hole 82 ... Coolant inlet manifold hole 84 ... Coolant outlet manifold hole DESCRIPTION OF SYMBOLS 100 ... Fuel cell stack 140,140a, 140b, 140u, 140d ... Single cell GK1-GK5 ... Gasket GK51 ... Attached elastic part GK5b ... Gasket

Claims (1)

A fuel cell stack in which a plurality of single cells and a gasket sandwiched between any two adjacent single cells are laminated,
The single cell includes a membrane electrode gas diffusion layer assembly, a resin frame bonded around the membrane electrode gas diffusion layer assembly, a first separator in contact with the first surface of the resin frame, and the resin frame. A second separator in contact with the second surface,
The gasket is disposed between the first separator and the second separator, and at least a part of the gasket runs along the outer periphery of the first separator,
A peripheral portion of the resin frame extends outward from the outer periphery of the first separator;
In the first surface of the resin frame, the peripheral portion of the resin frame has a plurality of first protrusions protruding in the stacking direction of the single cells,
In the second surface of the resin frame, the peripheral portion of the resin frame has a second protrusion protruding in the stacking direction at a position between the two adjacent first protrusions,
An outer peripheral portion of the second separator is pressed by the plurality of first convex portions of one of the two single cells and the second convex portion of the other single cell. Yes,
Fuel cell stack.

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