Fuel cell stack gas connection structure and manufacturing process thereof and fuel cell having the same

Abstract

The present invention relates to a stack gas connection structure, a manufacturing process thereof, and a fuel cell having the same. The stack gas connection structure includes a stack end plate and a gas connector, wherein the stack end plate is provided with a mounting through-hole; further comprising a rivet adapted to the mounting through-hole; the rivet is sleeved at the mounting through-hole and riveted to the stack end plate; the gas connector is adapted to the rivet and is arranged in the hollow cavity of the rivet. The solution provided in the present application can replace the threaded connection between the stack end plate and the gas connector by connecting the rivet to the axial hole of the stack end plate. When the stack end plate and the rivet are deformed, the stress on the contact position is dispersed. Without changing the material of the stack end plate and the gas connector to ensure the existing performance, the problem of gas leakage caused by poor sealing due to cracking of the stack end plate is effectively solved, thereby further improving the performance of the stack and the service life of the fuel cell. In addition, the structure is simple and easy to install.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a fuel cell stack gas connection structure, a manufacturing process thereof, and a fuel cell having the same. Background Art

[0002] A hydrogen fuel cell is a device that converts hydrogen energy into chemical energy. Its working principle is that hydrogen and oxygen react to produce water, providing energy and releasing heat. It has the advantages of being clean, environmentally friendly, and having high energy conversion efficiency.

[0003] The hydrogen fuel cell stack (stack) is the site where the chemical reaction of hydrogen fuel occurs in the fuel cell and is the core of the fuel cell. The stack includes various components such as the stack connector and stack end plates. The stack connector functions as the input and output connector for the stack's hydrogen, oxygen, and cooling water circuits and is generally installed on the stack end plates. When the stack is operating, hydrogen and oxygen respectively provide gas supply and exhaust to the fuel cell through the stack gas channels formed by the gas connectors (including the input and output connectors for the hydrogen and oxygen circuits) and the stack end plates. Therefore, the stack's inlet and outlet gas connections are particularly important.

[0004] In the existing technology, the end plate of the fuel cell stack is generally made of composite materials or epoxy resin plates, and the gas connector is generally made of stainless steel S316, and the gas connector is fixed to the end plate of the fuel cell stack by means of male and female threads. With the rapid development of fuel cells, they are gradually optimized towards small size and high specific power. Changing the gas connector to a small gas connector as much as possible will further cause stress concentration at the contact position between the end plate of the fuel cell stack and the gas connector. At the same time, when the gas supply flow pressure is frequently switched, more heat will be generated. Due to the large difference in material properties between the end plate of the fuel cell stack and the gas connector, and the rigid collision they will produce during the fuel cell stack reaction, when subjected to large stress, the contact position between the end plate of the fuel cell stack and the gas connector is prone to plastic deformation, which will cause cracking due to brittleness problems. Moreover, during the long-term operation of the hydrogen fuel cell, due to the different degrees of thermal deformation of the gas connector and the end plate of the fuel cell stack, long-term gas leakage will affect the performance of the fuel cell stack and may even cause the failure of the hydrogen fuel cell, resulting in immeasurable safety and economic losses.

[0005] Therefore, there is an urgent need to design a fuel cell gas connection structure that can effectively solve the gas leakage problem caused by different degrees of thermal deformation of different materials without changing the material of the fuel cell end plate and gas joint to ensure the existing performance, further improve the performance of the fuel cell and the service life of the hydrogen fuel cell, and the structure is simple and easy to install. Summary of the Invention

[0006] In order to overcome the problems existing in the related art, the present application provides a fuel cell stack gas connection structure, a manufacturing process thereof, and a fuel cell having the same. The fuel cell stack gas connection structure can replace the threaded connection between the fuel cell stack end plate and the gas joint by connecting the fuel cell stack end plate with the axial hole through a rivet. When the fuel cell stack end plate and the rivet are deformed, the stress at the contact position is dispersed, thereby effectively solving the problem of cracking of the fuel cell stack end plate due to brittleness, further improving the performance of the fuel cell stack and the service life of the hydrogen fuel cell, and the structure is simple and easy to install.

[0007] The first aspect of the present application provides a fuel cell stack gas connection structure, including a fuel cell stack end plate and a gas connector, wherein the fuel cell stack end plate is provided with a mounting through hole; and further comprising a rivet adapted to the mounting through hole; the rivet is sleeved on the mounting through hole and riveted to the fuel cell stack end plate; the gas connector is adapted to the rivet and is arranged in the hollow cavity of the rivet.

[0008] In one embodiment, a sealing ring is further included, and the sealing ring is sleeved on the rivet.

[0009] In one embodiment, a stepped through hole is coaxially provided at the end of the mounting through hole, and the stepped through hole includes a first step through hole and a second step through hole with gradually decreasing apertures from the outside to the inside.

[0010] In one embodiment, the cross-sectional shape of the rivet is an I-shape; the first stepped through hole is tightly fitted with both ends of the rivet.

[0011] In one embodiment, the hole height of the second stepped through hole is greater than the height of the sealing ring, and the width of the step of the second stepped through hole is less than or equal to the thickness of the sealing ring.

[0012] In one embodiment, an internal thread is provided on the cavity wall of the hollow cavity; and an external thread matching the internal thread is provided on the gas connector.

[0013] In one embodiment, the sealing rings include two, which are respectively arranged at both ends of the rivet.

[0014] In one embodiment, the rivet is made of stainless steel S316.

[0015] A second aspect of the present application provides a fuel cell, comprising the above-mentioned fuel cell stack gas connection structure.

[0016] A third aspect of the present application provides a manufacturing process for a fuel cell stack gas connection structure, which is used to manufacture the fuel cell stack gas connection structure. The specific steps include:

[0017] Setting mounting through holes on the stack end plate through a through-hole processing step;

[0018] Sleeve the rivet on the installation through hole and rivet it to the stack end plate;

[0019] Use a riveting tool to press the rivets into an I-shape;

[0020] Connect the gas fitting with the rivet.

[0021] The technical solution provided by the present application may include the following beneficial effects: when it is necessary to fix the gas connector on the stack end plate, a rivet that is compatible with the mounting through hole on the stack end plate is first riveted to the stack end plate, and then a gas connector that is compatible with the rivet is set in the hollow cavity of the rivet, so that the gas connector can be fixed on the stack end plate; compared with the prior art method of directly fixing the gas connector on the stack end plate through the threads on the stack end plate and the gas connector, since the contact between the threads is point or line contact, the stress on the contact position is relatively large, and when the stack generates heat during operation, the deformation degree is different due to different materials, which can easily cause the stack end plate to be brittle. This causes the thread to crack. When the gas connection structure of the fuel cell stack of the present application is adopted, since the fuel cell stack end plate and the rivet are matched with the through hole and the shaft, compared with the threaded matching in the prior art, the contact position is a surface, which effectively improves the problem of stress concentration at the contact position. The rivet is connected to the shaft hole of the fuel cell stack end plate instead of the threaded connection between the fuel cell stack end plate and the gas connector. When the fuel cell stack end plate and the rivet are deformed, the stress at the contact position is dispersed. Without changing the material of the fuel cell stack end plate and the gas connector to ensure the existing performance, the gas leakage problem caused by poor sealing due to cracking of the fuel cell stack end plate is effectively solved, thereby further improving the performance of the fuel cell stack and the service life of the hydrogen fuel cell. In addition, the structure is simple and easy to install.

[0022] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0024] Figure 1 is a cross-sectional schematic diagram of a gas connection structure of a fuel cell stack shown in an embodiment of the present application;

[0025] Figure 2 is a cross-sectional schematic diagram of the fuel cell stack gas connection structure shown in an embodiment of the present application when no rivets are installed;

[0026] Figure 31 is a schematic structural diagram of a rivet shown in an embodiment of the present application;

[0027] Figure 4 It is a flow chart of the manufacturing process of the fuel cell gas connection structure shown in the embodiment of the present application.

[0028] Reference numerals:

[0029] 1. Stack end plate; 12. Mounting through-hole; 121. First step through-hole; 122. Second step through-hole; 2. Gas connector; 3. Rivet; 31. Hollow cavity; 32. First transverse portion; 33. Vertical portion; 34. Second transverse portion; 4. Sealing ring. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0031] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0032] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] In the existing technology, the stack end plate and the gas connector are generally fixed to the stack end plate through the cooperation of male and female threads. When the gas supply flow pressure is frequently switched, a lot of heat will be generated. Due to the large difference in material properties between the stack end plate and the gas connector, and the rigid collision they will produce during the stack reaction, when subjected to large stress, the contact position of the stack end plate is prone to plastic deformation, which will cause cracking due to brittleness problems, resulting in a decrease in sealing performance, and even cause the failure of the hydrogen fuel cell, resulting in immeasurable safety and economic losses.

[0034] In response to the above problems, an embodiment of the present application provides a fuel cell stack gas connection structure, which can replace the threaded connection between the fuel cell stack end plate and the gas joint by connecting the fuel cell stack end plate with the axial hole of the fuel cell stack end plate through a rivet. When the fuel cell stack end plate and the rivet are deformed, the stress at the contact position is dispersed, thereby effectively solving the cracking problem caused by the brittleness of the fuel cell stack end plate, further improving the performance of the fuel cell stack and the service life of the hydrogen fuel cell. In addition, the structure is simple and easy to install.

[0035] The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0036] Example 1

[0037] See also Figure 1-Figure 3 , Figure 1 It is a cross-sectional schematic diagram of the fuel cell stack gas connection structure shown in an embodiment of the present application.

[0038] The fuel cell gas connection structure of the present application includes a fuel cell end plate 1, a gas connector 2 and a rivet 3. The fuel cell end plate 1 is made of composite material or epoxy resin injection molding, and the gas connector 2 and the rivet 3 are made of stainless steel S316.

[0039] The stack end plate 1 is provided with a mounting through hole 12; the rivet 3 is adapted to the mounting through hole 12, so that the rivet 3 can be sleeved on the mounting through hole 12 and riveted to the stack end plate 1; the rivet 3 includes a hollow cavity 31, and the shape and size of the hollow cavity 31 are adapted to the gas connector 2, so that the gas connector 2 can be arranged in the hollow cavity 31 of the rivet 3 and communicated with the hollow cavity 31, and the gas connector 2 is fixed to the stack end plate 1. Specifically, an internal thread is provided on the cavity wall of the hollow cavity 31; the gas connector 2 is provided with an external thread adapted to the internal thread.

[0040] When supplying gas, the gas enters the hollow cavity 31 of the rivet 3 from the gas connector 2, and then enters the interior of the fuel cell stack from the hollow cavity 31; when exhausting gas, the gas enters the hollow cavity 31 of the rivet 3 from the interior of the fuel cell stack, and then enters the gas connector 2 from the hollow cavity 31, thereby exhausting the gas.

[0041] In order to further reduce the problems of cracking and gas leakage caused by different degrees of thermal deformation and brittleness of the stack end plate 1 and the rivet 3, the stack gas connection structure also includes a sealing ring 4. The cross-section of the sealing ring 4 is O-shaped and is adapted to the vertical portion 33 of the rivet 3, so that the sealing ring 4 can fit tightly with the vertical portion of the rivet 3 after being sleeved on the rivet 3; in order to increase the service life of the sealing ring 4, the material of the sealing ring 4 is made of hydrogen-resistant material, including any one of polytetrafluoroethylene, ethylene propylene diene monomer (EPDM) and composite polyurethane material; in order to further improve the sealing performance while reducing unnecessary waste, preferably, the sealing ring 4 includes 2, which are respectively arranged at both ends of the rivet 3.

[0042] Specifically, in order to limit the rivet 3 and the sealing ring 4, the end of the mounting through hole 12 is coaxially provided with a stepped through hole. Since the gas connector 2 may be excessively reduced when the number of layers of the stepped through hole is too many, in order to meet the gas supply of the gas connector 2 as much as possible, preferably, the stepped through hole includes a first step through hole 121 and a second step through hole 122 with a gradually decreasing aperture from the outside to the inside; that is, the aperture of the first step through hole 121 is larger than the aperture of the second step through hole 122, and the first step through hole 121 is closer to the outer end than the second step through hole 122; the first step through hole 121 is tightly connected to both ends of the rivet 3 Matching, specifically, the rivet 3 includes a first transverse portion 32 and a second transverse portion 34 and a vertical portion 33 located between the first transverse portion 32 and the second transverse portion 34, so that the cross-sectional shape of the rivet 3 is an I-shape; the aperture and hole height of the first step through hole 121 are adapted to the width and height of the two ends of the rivet 3, that is, the aperture and hole height of the first step through hole 121 are adapted to the width and height of the first transverse portion 32 and the second transverse portion 34 of the rivet 3, respectively, so that the first transverse portion 32 and the second transverse portion 34 of the rivet 3 can be placed just in the first step through hole 121 and tightly matched with the stack end plate 1.

[0043] In order to leave enough space for the sealing ring 4 to deform and prevent the sealing ring 4 from being damaged due to excessive extrusion, the hole height of the second step through hole 122 is greater than the height of the sealing ring 4; and the width of the step of the second step through hole 122 is less than or equal to the thickness of the sealing ring 4, so that when the sealing ring 4 is sleeved on the vertical part of the rivet 3 and the rivet 3 is assembled on the mounting through hole 12, the sealing ring 4 can be limited at the second step through hole 122 and tightly cooperate with the rivet 3 and the stack end plate 1 respectively, thereby further strengthening the seal between the stack end plate 1 and the rivet 3.

[0044] It should be noted that, firstly, the sizes of the first transverse portion 32 and the second transverse portion 34 can be the same or different, that is, the sizes of the first step through holes 121 at both ends of the mounting through hole 12 can be the same or different, which is not limited here; secondly, Figure 2 The direction of rivet assembly (i.e., the direction of the arrow) is the height direction, and the direction perpendicular to the arrow direction is the width direction. The height in this application is the length in the height direction, and the width is the length in the width direction. The thickness of the sealing ring is the length of the sealing ring in the width direction, and the width of the second step through hole step is the width of the step on one side thereof.

[0045] In the first embodiment of the present invention, when it is necessary to fix the gas connector on the end plate of the stack, a rivet that is compatible with the mounting through hole on the end plate of the stack is first riveted to the end plate of the stack, and then a gas connector that is compatible with the rivet is arranged in the hollow cavity of the rivet, so that the gas connector can be fixed to the end plate of the stack. Compared with the prior art method of directly fixing the gas connector to the end plate of the stack through the threads on the end plate of the stack and the gas connector, since the contact between the threads is point or line contact, the stress on the contact position is relatively large. When the stack generates heat during operation, the deformation degree is different due to different materials, which can easily cause the threads of the end plate of the stack to crack due to brittleness. When the stack gas connection structure of the present application is adopted, since the stack end plate and the rivet are matched with the through hole and the shaft, compared with the threaded match in the prior art, the contact position is a surface, which effectively improves the problem of stress concentration at the contact position. The rivet is connected to the shaft hole of the stack end plate instead of the threaded connection between the stack end plate and the gas connector. Therefore, when the stack end plate and the rivet are deformed, the stress at the contact position can be dispersed. Without changing the material of the stack end plate and the gas connector to ensure the existing performance, the gas leakage problem caused by poor sealing due to cracking of the stack end plate can be effectively solved, thereby further improving the performance of the stack and the service life of the hydrogen fuel cell. In addition, the structure is simple and easy to install.

[0046] Example 2

[0047] At present, the cross-sectional shape of the rivet is generally T-shaped. In order to facilitate connection, a cold riveting process is used to rivet the rivet nut before riveting. For example, in CN108627116A, the internal thread is installed in the blind hole of the insulation cotton through the rivet nut. However, the traditional rivet nut is not suitable for riveting materials with larger thickness, and there is a gap between the rivet rod and the hole, and sealing cannot be achieved. Therefore, the traditional rivet nut cannot be used in the gas connection structure of the fuel cell stack in the field of fuel cells.

[0048] In order to solve the above problems, this application proposes a corresponding solution, please refer to Figure 4 , specifically:

[0049] The present application also provides a manufacturing process for a fuel cell stack gas connection structure, which is used to manufacture the fuel cell stack gas connection structure. The specific steps include:

[0050] S1. Setting mounting through holes on the stack end plate through a through-hole processing step;

[0051] S2. Sleeve the rivet on the mounting through hole and rivet it to the stack end plate;

[0052] S3, using a riveting tool to press the rivet into an I-shape;

[0053] S4. Connect the gas connector with the rivet.

[0054] In S1, the through-hole processing step includes forming the mounting through-hole by machining or direct mold injection molding, and the mounting through-hole is a stepped through-hole.

[0055] In S2, before the rivet is placed on the mounting hole, a sealing ring is placed on the position where the vertical portion of the rivet is connected to the first horizontal portion, and then the rivet is inserted from one end of the mounting hole (such as Figure 2 ), so that the sealing ring is located at the position of the second step through hole, and then the rivet is riveted to the stack end plate. At this time, the first transverse portion of the rivet is located at the upper end of the vertical portion.

[0056] In S3, before using a riveting tool to press the rivet into an I-shape, the stack end plate is rotated 180 degrees. At this time, the first transverse portion of the rivet is located at the lower end of the vertical portion. A sealing ring is then placed on the vertical portion of the rivet so that the sealing ring can be located at the position of the other second step through hole. Then, a riveting tool is used to press the top of the vertical portion of the rivet into a second transverse portion. The shape and size of the second transverse portion are compatible with the other first step through hole, and the sealing ring can also be limited at the second step through hole to prevent the sealing ring from falling.

[0057] In S4, the gas connector is connected to the rivet by engaging the external thread on the gas connector with the internal thread on the rivet, thereby completing the manufacture of the fuel cell stack gas connection structure.

[0058] In an embodiment of the present application, a mounting through hole is formed in the stack end plate by machining or direct mold injection molding, and the rivet is then riveted into an I-shaped structure that matches the mounting through hole by a riveting tool. This allows the rivet to be suitable for stack end plates with a thicker material, thereby achieving connection between the gas connector and the stack end plate, reducing gas leakage caused by cracking of the stack end plate due to brittleness. Moreover, the mutual cooperation between the mounting through hole and the rivet can also effectively limit the sealing ring, further improving the airtightness of the stack gas connection structure.

[0059] Example 3

[0060] Based on the above embodiments, the present application also provides a fuel cell, including the above-mentioned fuel cell stack gas connection structure.

[0061] The specific structure of the fuel cell gas connection structure is detailed in the above embodiment and will not be repeated here.

[0062] In an embodiment of the present application, a fuel cell using the stack gas connection structure provided by the present application is adopted. Since the stack end plate and the rivet are matched with a through hole and an axis, compared with the threaded match in the prior art, the contact position is a surface, which effectively improves the problem of stress concentration at the contact position. Therefore, when the stack end plate and the rivet are deformed, the stress at the contact position is dispersed, thereby effectively solving the cracking of the stack end plate caused by brittleness, further improving the airtightness of the stack gas connection structure, and thus improving the service life and safety performance of the fuel cell.

[0063] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated again here.

[0064] The scheme of the present application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also be aware that the actions and modules involved in the description are not necessarily required for this application. In addition, it is understood that the steps in the method of the embodiment of the present application can be adjusted in sequence, merged and deleted according to actual needs, and the modules in the device of the embodiment of the present application can be merged, divided and deleted according to actual needs.

[0065] The flow charts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems and methods according to multiple embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a part of a module, program segment or code, and the part of the module, program segment or code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0066] The embodiments of the present application have been described above. The above description is illustrative and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements to the technology in the market, or to enable other persons skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell gas connection structure, comprising a fuel cell end plate (1) and a gas connector (2), wherein the fuel cell end plate (1) is provided with a mounting through hole (12); characterized in that: It also includes a rivet (3) adapted to the mounting through hole (12); the rivet (3) is an I-shaped structure adapted to the mounting through hole (12); The rivet (3) is sleeved on the mounting through hole (12) and riveted to the stack end plate (1); The gas connector (2) is adapted to the rivet (3) and is arranged in the hollow cavity (31) of the rivet (3).

2. The fuel cell stack gas connection structure according to claim 1, characterized in that: It also includes a sealing ring (4), which is sleeved on the rivet (3).

3. The fuel cell stack gas connection structure according to claim 2, characterized in that: A stepped through hole is coaxially provided at the end of the mounting through hole (12), and the stepped through hole comprises a first stepped through hole (121) and a second stepped through hole (122) whose apertures decrease step by step from the outside to the inside.

4. The fuel cell stack gas connection structure according to claim 3, characterized in that: The cross-sectional shape of the rivet (3) is an I-shaped shape; The first stepped through hole (121) is tightly fitted with both ends of the rivet (3).

5. The fuel cell stack gas connection structure according to claim 3, characterized in that: The hole height of the second stepped through hole (122) is greater than the height of the sealing ring (4), and the width of the step of the second stepped through hole (122) is less than or equal to the thickness of the sealing ring (4).

6. The fuel cell stack gas connection structure according to claim 1, characterized in that: The cavity wall of the hollow cavity (31) is provided with an internal thread; The gas connector (2) is provided with an external thread that matches the internal thread.

7. The fuel cell stack gas connection structure according to claim 2, characterized in that: The sealing rings (4) include two, which are respectively arranged at the two ends of the rivet (3).

8. The fuel cell stack gas connection structure according to claim 1, characterized in that: The material of the rivet (3) is stainless steel S316.

9. A manufacturing process for a fuel cell gas connection structure, characterized in that: For manufacturing the fuel cell stack gas connection structure according to any one of claims 1 to 8, the specific steps include: Providing a mounting through hole (12) on the stack end plate (1) through a through hole processing step; The rivet (3) is sleeved on the mounting through hole (12) and riveted to the stack end plate (1); Using a riveting tool to press the rivet (3) into an I-shaped shape; Connect the gas connector (2) with the rivet (3).

10. A fuel cell, characterized in that: It comprises the fuel cell stack gas connection structure as described in any one of claims 1 to 8.

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