fuel cells

Abstract

The present invention provides a fuel cell capable of ensuring the gas sealing performance of a seal without relying on the mechanical strength of a gas manifold, thereby preventing a reduction in gas sealing performance and reducing costs. The fuel cell comprises: a fuel cell stack; a pair of end plates that secure and retain the fuel cell stack from both ends; and a plurality of gas manifolds secured to the fuel cell stack and the end plates via seals for supplying fuel and oxidant to the fuel gas flow passages and oxidant gas flow passages of the fuel cell stack. The fuel cell comprises a gas manifold fixing band comprising: a pressure plate disposed in contact with the back surface of the gas manifold; a pressure plate connecting portion that connects pressure plates disposed on the back surfaces of adjacent gas manifolds; and a band fastening portion that connects and secures a series of pressure plates to both ends of the pressure plate connecting portion.

Description

Technical Field

[0001] Embodiments of the present invention relate to fuel cells. Background Art

[0002] A fuel cell is a power generation device that uses an electrochemical reaction by feeding a fuel cell stack composed of multiple stacked unit cells with a fuel such as hydrogen and an oxidant such as air. This converts the chemical energy of the fuel directly into electrical energy, which is then extracted externally. Each unit cell in a fuel cell stack consists of an anode and cathode electrodes placed on either side of an electrolyte, along with a separator between these electrodes.

[0003] The diaphragm is formed with fuel gas flow channels and oxidant gas flow channels that connect to the anode and cathode electrodes. Furthermore, a pair of end plates are provided at both ends of the fuel cell stack, securing the fuel cell stack in the stacking direction of the unit cells and thereby maintaining the stack.

[0004] Furthermore, fuel cells are equipped with gas manifolds to supply fuel and oxidant to the fuel gas and oxidant gas passages of the diaphragms. The method of attaching the gas manifold to the outside of the fuel cell stack is called an external manifold method. In an external manifold method fuel cell, the gas manifold is fixed to the end plate.

[0005] When the gas manifold is fixed to the end plate, elastic seals are inserted between the fuel cell stack and the gas manifold, and between the end plate and the gas manifold. In the fuel cell, these seals prevent gas from leaking from the fuel cell stack and the gas manifold to the outside of the fuel cell stack and the gas manifold.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 5086581 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] In fuel cells, during fuel cell operation, gas or cooling water may flow through the fuel cell, causing the gas manifold to swell near the center, causing the gas manifold to deform away from the fuel cell stack. In such cases, deformation of the gas manifold can cause the seal to separate from any of the fuel cell stack, end plate, or gas manifold, potentially compromising the seal's gas sealing performance.

[0011] In recent years, fuel cell capacity has been increasing, and with it, fuel cells are trending toward larger sizes. Consequently, gas manifold deformation increases, making it easier for seals to separate from the gas manifold, etc. This makes it difficult to ensure the seal's gas-tightness.

[0012] In order to prevent the gas sealing performance of the seal from being reduced, it is necessary to suppress the deformation of the gas manifold, and it is important that the gas manifold has sufficient mechanical strength.

[0013] (1) The gas manifold is made of a material that is not easily deformed.

[0014] (2) Make the gas manifold a thick plate structure,

[0015] (3) Take measures such as providing a structure with ribs on the back of the gas manifold.

[0016] However, if the gas manifold is to be given sufficient mechanical strength, the gas manifold itself becomes expensive in the aforementioned (1) and (2), and the manufacturing cost increases in (3), leading to a cost surge. Therefore, in conventional fuel cells, it is desirable to prevent the reduction in gas sealing performance caused by the seals while reducing costs. In particular, in recent years, as fuel cells have become larger in capacity, costs have also tended to increase, making cost reduction a top priority.

[0017] An object of the present invention is to provide a fuel cell capable of ensuring the gas sealing performance of a seal without relying on the mechanical strength of a gas manifold, thereby preventing a decrease in the gas sealing performance and reducing costs.

[0018] Means for solving technical problems

[0019] The fuel cell of the embodiment comprises: a fuel cell stack, which is composed of a plurality of unit cells stacked together, wherein the unit cells are composed of an anode electrode and a cathode electrode arranged on both sides of an electrolyte, and a diaphragm, which is arranged in contact with the anode electrode and the cathode electrode respectively and has a fuel gas flow path and an oxidant gas flow path; a pair of end plates, which fasten and hold the fuel cell stack from both ends; and a plurality of gas manifolds, which are fixed to the fuel cell stack and the end plates via seals, and are used to supply fuel and oxidant to the fuel gas flow paths and the oxidant gas flow paths of each of the fuel cell stacks, the fuel cell having a gas manifold fixing belt, which comprises: a pressure plate, which is arranged in contact with the back side of the gas manifold; a pressure plate connecting portion, which connects the pressure plates arranged on the back sides of adjacent gas manifolds to each other; and a belt fastening portion, which connects and fastens a series of the pressure plates to both ends of the pressure plate connecting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a perspective view of the first embodiment.

[0021] Figure 2A It is a side view of the first embodiment.

[0022] Figure 2B It is an AA cross-sectional view of the first embodiment.

[0023] Figure 3 It is an exploded perspective view of the first embodiment.

[0024] Figure 4 It is an enlarged exploded perspective view of the main parts of the first embodiment.

[0025] Figure 5A This is a side view of the gas manifold fixing band of the first embodiment before being tightened.

[0026] Figure 5B It is a BB cross-sectional view of the state before the gas manifold fixing band is tightened according to the first embodiment.

[0027] Figure 6 It is a perspective view of the second embodiment.

[0028] Figure 7A It is a side view of the second embodiment.

[0029] Figure 7B It is a CC cross-sectional view of the second embodiment.

[0030] Figure 8 It is a perspective view of the third embodiment.

[0031] Figure 9A It is a side view of the third embodiment.

[0032] Figure 9B It is an EE cross-sectional view of the third embodiment.

[0033] Figure 10 It is a perspective view of the fourth embodiment.

[0034] Figure 11 This is a perspective view of a fuel cell equipped with a steel belt.

[0035] Figure 12A It is a side view of a fuel cell equipped with a steel belt.

[0036] Figure 12B This is a FF cross-sectional view of a fuel cell equipped with a steel belt.

[0037] Figure 13 It is a partial cross-sectional view of a fuel cell stack. DETAILED DESCRIPTION

[0038] Hereinafter, a fuel cell according to an embodiment will be described with reference to the drawings.

[0039] (First embodiment)

[0040] Figure 1 is a perspective view showing the structure of a fuel cell according to the first embodiment. Figure 2A It is a side view. Figure 2B yes Figure 2A AA cross-sectional view, Figure 3 As shown in these figures, the fuel cell stack 1 is fixed in a stacked state by fastening a pair of end plates 2 using a plurality of tie rods 3 . Figure 13 1 is a partial cross-sectional view of the fuel cell stack 1. Figure 13 As shown, the fuel cell stack 1 is formed by stacking a plurality of unit cells 11. The unit cells 11 are composed of an anode electrode 111 and a cathode electrode 112 arranged on both sides of an electrolyte 110, and a separator 12. The separator 12 is arranged in contact with the anode electrode 111 and the cathode electrode 112, respectively, and has a fuel gas flow passage F121 and an oxidant gas flow passage F122. The fuel gas flow passage F121 and the oxidant gas flow passage F122 extend in directions perpendicular to each other, for example, and the fuel gas flow passage F121 is disposed at a position perpendicular to the direction of the fuel gas flow passage F121. Figure 13 The oxidant gas flow passage F122 is formed to extend in a direction perpendicular to the paper surface. Figure 13 The center extends in the direction along the paper surface.

[0041] A resin gas manifold 5 is attached to each side of the fuel cell stack 1 and the end plate 2 via a seal 4. The gas manifold 5 is secured to the end plate 2 and the fuel cell stack 1 by screwing gas manifold fixing bolts 6, which pass through holes at both ends of the gas manifold 5, into threaded holes in the end plate 2. The gas manifold 5 is used to supply fuel and oxidant to the fuel gas flow passages and oxidant gas flow passages in the fuel cell stack 1.

[0042] A gas manifold fixing band 7 is provided near the center of the gas manifold 5 so as to be wound around the outside of the gas manifold 5 on four sides. Figure 4 As also shown in FIG, the gas manifold fixing band 7 includes a pressing plate 7a, a pressing plate connecting portion 7b, and a band fastening portion 7c.

[0043] The pressure plate 7a is a plate-shaped member made of steel and has sufficient mechanical strength (rigidity) to prevent significant deformation even when the gas manifold fixing band 7 is tightened. The surface in contact with the gas manifold 5 is smoothed, resulting in low frictional resistance with the gas manifold 5. The pressure plate 7a is thicker and more rigid than the pressure plate connecting portion 7b.

[0044] The pressure plate connecting portion 7b is a thin plate-shaped member made of pre-bent steel. It is placed in contact with the pressure plate 7a and is placed in a state where the pressure plate 7a is pressed toward the gas manifold 5 when the gas manifold fixing band 7 is tightened. The pressure plate connecting portion 7b has a rigidity that allows it to deform when tightened by the band tightening portion 7c. It is made of a member that is thinner and less rigid than the pressure plate 7a. Figure 4 In FIG. 1 , the pressing plate and the fixing screw 7d of the connecting portion for fixing the pressing plate 7a and the pressing plate connecting portion 7b are shown.

[0045] Belt fastening portions 7c are provided at both ends of the series of pressure plates 7a and pressure plate connecting portions 7b. The belt fastening portions 7c are two components connected to the ends of the pressure plate connecting portion 7b. They are configured such that, by tightening them toward each other using bolts 7e and nuts 7f, each pressure plate 7a is pressed against the gas manifold 5. A fastening elastic member 7g, composed of an elastic body such as a disc spring, coil spring, or rubber, is inserted between the bolts of the fastening portion and the belt fastening portions 7c.

[0046] When the gas manifold fixing band 7 is tightened, the seal 4 is compressed and deformed, and the gas manifold 5 moves toward the fuel cell stack 1. Depending on the amount of movement, the pressure plate 7a moves relative to the gas manifold 5. However, even if the pressure plate 7a moves, the pressure plate connecting portion 7b is not in contact with the gas manifold 5. In this embodiment, the length of the pressure plate 7a is made longer than the length of the contact surface with the gas manifold 5. Therefore, even if the pressure plate 7a moves, the pressure plate connecting portion 7b is not in contact with the gas manifold 5. Figure 3 As shown, the gas manifold 5 is provided with a gas manifold pipe connection portion 8 .

[0047] (Function and Effect)

[0048] Figure 2B 1 is a cross-sectional view showing a state where the gas manifold fixing band 7 is fastened in the first embodiment. Figure 2B As shown, the seal 4 between the gas manifold 5 and the fuel cell stack 1 is Figure 5B The state before the gas manifold fixing band 7 is tightened is shown to be thinner and crushed. The gas manifold 5 is also Figure 2B is closer to the fuel cell stack 1 in the state.

[0049] At this time, since the pressure plate connecting portion 7b is a thin plate-shaped member, it is in contact with the corner of the pressure plate 7a. The bending angle of the bent portion of the pressure plate connecting portion 7b changes, so that each pressure plate 7a remains in contact with the back surface of the gas manifold 5. However, since the length of the pressure plate connecting portion 7b hardly changes, the pressure plate 7a moves relative to the gas manifold 5.

[0050] exist Figure 2B In the cross-sectional view, the left and right pressure plates 7a are Figure 5B Towards Figure 2B , it slides upward simultaneously with the change in state. The belt fastening portion 7c also slides toward a position closer to the center. However, even if the pressure plate 7a slides, the fastening force of the gas manifold fixing belt 7 generates a force that presses the gas manifold 5 toward the fuel cell stack 1 via the pressure plate connecting portion 7b and the pressure plate 7a. Furthermore, since the frictional resistance of the contact surface between the pressure plate 7a and the gas manifold 5 is low, the gas manifold 5 does not move horizontally relative to the contact surface with the seal 4, and a uniform compressive load is applied to the sealing surface to ensure sealing.

[0051] For comparison, Figure 11 、 Figure 12A 、 Figure 12B FIG2 shows a conventional fuel cell in which a steel belt 101 is provided. When a thin steel belt 101 is directly provided on the periphery of a gas manifold and fastened with a steel belt fastening portion 11a, if the seal is crushed by the fastening, the steel belt 101 slides and moves on the gas manifold, and the curved portion of the steel belt that contacts the corner of the gas manifold also moves and is stretched, forming a new curved portion in the portion that contacts the corner of the manifold.

[0052] However, if the steel belt 101 is not sufficiently thin, the gas manifold will be stretched by the curved portion of the steel belt 101 as it moves, causing it to move horizontally relative to the contact surface with the seal, or a uniform compressive load will not be applied to the sealing surface. Furthermore, if the steel belt 101 is thin, its low tensile strength will prevent sufficient tightening force from being applied, or it may be used under high tensile stress, resulting in increased deformation and a tendency for the tightening force to decrease over time.

[0053] On the other hand, in the first embodiment, the above-mentioned operations and effects can be obtained.

[0054] (Second embodiment)

[0055] Figure 6 、 Figure 7A 、 Figure 7B The structure of the fuel cell of the second embodiment is shown. In the first embodiment described above, as Figure 4 As shown in the main part of the enlarged exploded perspective view, the pressure plate connecting portion 7b of the gas manifold fixing belt 7 is composed of a thin plate-shaped member of a steel material connected as a whole. In contrast, in the second embodiment, as shown in FIG. Figure 6 、 Figure 7A 、 Figure 7BAs shown, the pressure plate connecting portion 7b of the gas manifold fixing band 7 connects two adjacent pressure plates 7a and is composed of a total of four thin steel plate-shaped members. The remaining structure is the same as that of the first embodiment. The operation and effects are also the same as those of the first embodiment.

[0056] (Third embodiment)

[0057] Figure 8 、 Figure 9A 、 Figure 9B The structure of the fuel cell of the third embodiment is shown in FIG. Figure 8 、 Figure 9A 、 Figure 9B As shown, in each gas manifold 5 of the third embodiment, a convex portion 5a is provided at a portion in contact with the pressure plate 7a of the gas manifold fixing band 7. There are a plurality of convex portions 5a. Figure 8 、 Figure 9A 、 Figure 9B In the example shown, three protrusions 5a are provided at intervals on each gas manifold 5. These protrusions 5a make the vicinity of the sealing portion ( Figure 3 The portion where the seal 4 is located is shown as protruding toward the pressure plate 7a, thereby reducing the contact resistance with the pressure plate 7a. The other structures are the same as those of the first embodiment.

[0058] The function and effect are the same as those of the first embodiment, but since the contact resistance between the gas manifold 5 and the pressure plate 7a is reduced, it is difficult for the gas manifold 5 to move horizontally relative to the contact surface with the seal 4, or the surface pressure of the sealing surface is difficult to become uneven, making it easier to ensure sealing.

[0059] (Fourth embodiment)

[0060] Figure 10 The structure of the fuel cell of the fourth embodiment is shown in FIG. In the first embodiment, both ends of the gas manifold 5 are fixed to the end plate 2 by the gas manifold fixing bolts 6. Figure 10 As shown, in the fourth embodiment, the gas manifold 5 is also secured at both ends with gas manifold securing bands 7. Therefore, a total of three gas manifold securing bands 7 are used. The remaining structure is the same as in the first embodiment, and the functions and effects are also the same as in the first embodiment.

[0061] (Other embodiments)

[0062] The embodiment described above is provided as an example of an embodiment of the present invention and is not intended to limit the scope of the invention. The embodiment of the present invention can be implemented in various other ways and can be omitted, replaced, or modified in various ways without departing from the scope of the invention. These embodiments and their modifications are included in the scope or spirit of the invention and are also included in the invention described in the claims and their equivalents.

[0063] For example, the friction coefficient may be reduced by applying a lubricant to one or both sides of the contact surface of the pressure plate 7 a with the gas manifold 5 or by attaching a member having low friction resistance thereto.

[0064] In addition, for example, even if the pressure plate connecting portion 7b is not made of thin steel, as long as the relative angle of adjacent pressure plates 7a is changed to maintain the state of contact between the back of each pressure plate 7a and the gas manifold 5, it can also be used by using a component with hooks at both ends to hook the hooks on the two ends of the pressure plate 7a, so that the connection angle between the pressure plate connecting portion 7b and the pressure plate 7a can be changed.

[0065] Furthermore, the gas manifold fixing band 7 can be combined with other fixing methods and can be used at any location as long as it is used at one or more locations.

[0066] [Explanation of Reference Numerals]

[0067] 1...fuel cell stack, 2...end plate, 3...pull rod, 4...seal, 5...gas manifold, 5a...protrusion, 6...gas manifold fixing bolt, 7...gas manifold fixing belt, 7a...pressure plate, 7b...pressure plate connecting portion, 7c...belt fastening portion, 7d...fixing screw of pressure plate connecting portion, 7e...connecting portion bolt, 7f...connecting portion nut, 7g...connecting portion elastomer, 8...piping connection portion of gas manifold, 11...unit cell, 12...diaphragm, 110...electrolyte, 111...anode electrode, 112...cathode electrode, F121...fuel gas flow passage, F122...oxidant gas flow passage.

Claims

1. A fuel cell comprising: A fuel cell stack comprising a plurality of stacked unit cells, each comprising an anode electrode and a cathode electrode disposed on opposite sides of an electrolyte, and a separator disposed in contact with the anode electrode and the cathode electrode, respectively, and having a fuel gas flow passage and an oxidant gas flow passage; a pair of end plates for fastening and holding the fuel cell stack from both ends; as well as A plurality of gas manifolds are fixed to the fuel cell stack and the end plate via seals, and are used to supply fuel and oxidant to the fuel gas flow passages and the oxidant gas flow passages of the fuel cell stack. The fuel cell is characterized by having a gas manifold fixing band, the gas manifold fixing band having: a pressure plate disposed in contact with the back surface of the gas manifold; a pressure plate connecting portion connecting the pressure plates provided on the back surfaces of the adjacent gas manifolds; and A belt fastening portion is used to connect and fasten a series of said pressing plates and both ends of said pressing plate connecting portion, When the gas manifold fixing band is tightened, the gas manifold does not move horizontally relative to the contact surface with the seal, but the pressure plate moves relative to the gas manifold, thereby generating a force that presses the gas manifold toward the fuel cell stack.

2. The fuel cell according to claim 1, wherein The pressure plate connecting portion is composed of a thin plate-shaped member that can be deformed when the belt fastening portion is fastened. The pressing plate is formed of a plate-shaped member that is thicker and has higher rigidity than the pressing plate connecting portion.

3. The fuel cell according to claim 2, wherein The pressure plate has the following structure: it is longer than the back side of the gas manifold with which the pressure plate contacts, and the pressure plate connecting portion does not contact the gas manifold in any state: a state before the gas manifold fixing belt is set and the seal is compressed and deformed, and a state after the gas manifold fixing belt is tightened, the seal is compressed and deformed, and the pressure plate moves relative to the gas manifold.

4. The fuel cell according to any one of claims 1 to 3, characterized in that A friction resistance reducing unit is provided for reducing friction resistance between the back surface of the gas manifold and the pressure plate.

5. The fuel cell according to claim 4, characterized in that The friction resistance reducing unit is a convex portion provided on the back surface of the gas manifold so as to reduce the contact area between the back surface of the gas manifold and the pressure plate.

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