JP7322720B2 - fuel cell case - Google Patents

Description

The present invention relates to a fuel cell case.

Conventionally, this type of fuel cell case is arranged so as to surround a power generation section having a fuel cell that generates power using anode gas and cathode gas, and a combustion section that burns anode off-gas to generate flue gas. A first cylindrical member having a through hole, a second cylindrical member disposed so as to surround the first cylindrical member and having a through hole in the side wall, and formed between the outer wall of the power generation section and the inner surface of the first cylindrical member. a first flow path through which combustion exhaust gas flows; a second flow path formed between the outer surface of the first tubular member and the inner surface of the second tubular member through which the cathode gas flows; the first flow path and the second tubular member; and a second communicating pipe member communicating between the second flow path and the outside of the second cylinder member (see, for example, Patent Document 1). . In this fuel cell case, the first communication pipe member and the first and second cylindrical members are formed by connecting one open end of the first communication pipe member and the through holes of the superimposed first and second cylindrical members. It is joined by crimping the peripheral portion.

JP 2015-141758 A

However, it is difficult to completely fix the combustion exhaust gas discharge pipe (first communicating pipe member) to the inner case (first tubular member) and the outer case (second tubular member) by joining by caulking. There is a risk that the exhaust pipe will rotate about its axis, or that the joint will loosen when an external force acts on the flue gas exhaust pipe in the radial direction. It is also conceivable to weld flue gas exhaust pipes to the respective through holes of both cases over the entire circumference so as to ensure the airtightness of the space (second flow path) between the inner case and the outer case. However, it is necessary to precisely align both through-holes so that there is no excessive clearance between the through-holes and the flue gas exhaust pipe, which requires high processing accuracy, resulting in an increase in manufacturing costs. Resulting in.

A main object of the fuel cell case of the present invention is to provide a fuel cell case in which a combustion exhaust gas discharge pipe for discharging combustion exhaust gas from a combustion section can be joined reliably at a low cost.

The fuel cell case of the present invention employs the following means in order to achieve the above main object.

The fuel cell case of the present invention is
an inner case containing a fuel cell and a combustion section for burning off-gas from the fuel cell and having a through hole in the wall surface;
an outer case that covers the inner case with a gap from the outer surface of the inner case so as to form a predetermined gas flow path, and has a through hole in a wall surface that communicates with the through hole of the inner case;
a combustion exhaust gas discharge pipe for discharging combustion exhaust gas from the combustion unit;
with
The flue gas discharge pipe is welded along the entire circumference to a through hole of one of the inner case and the outer case,
The inner case and the outer case have annular contact portions that contact each other around the through holes, and are joined by welding along the entire circumference of the contact portions.
This is the gist of it.

The fuel cell case of the present invention includes an inner case that accommodates a fuel cell and a combustion section and has a through hole in the wall surface; and an outer case having a through hole in its wall surface communicating with the combustion unit, and a combustion exhaust gas discharge pipe for discharging combustion exhaust gas from the combustion unit. The combustion exhaust gas discharge pipe is welded along the entire circumference to the peripheral portion of the through hole of one of the inner case and the outer case. The inner case and the outer case have annular contact portions that contact each other around the through holes, and are joined by welding along the entire circumference of the contact portions. When the flue gas discharge pipe is welded to the peripheries of the through holes of both the inner case and the outer case, the gap between the outer peripheral surface of the flue gas discharge pipe and the perimeter of the through hole of the inner case and the flue gas discharge It is necessary to precisely align the through-holes of the inner case and the outer case so that there is no excessive gap between the outer peripheral surface of the pipe and the periphery of the through-hole of the outer case. High precision is required. On the other hand, in the fuel cell case of the present invention, the combustion exhaust gas discharge pipe needs to be joined to only one of the inner case and the outer case. There is no need for alignment, and high precision is not required for the processing. As a result, it is possible to provide a fuel cell case in which the combustion exhaust gas discharge pipe can be joined more reliably at low cost.

In the fuel cell case of the present invention, the combustion exhaust gas discharge pipe may pass through the through hole of the outer case and be welded along the entire circumference to the peripheral portion of the through hole of the inner case. good.

Moreover, in the fuel cell case of the present invention, the inner case and the outer case may be joined by penetration welding at the contact portion. By doing so, the welding process can be easily automated, and the manufacturing cost can be further reduced.

1 is a schematic configuration diagram of a fuel cell system including a power generation module; FIG. 1 is a schematic configuration diagram of a power generation module; FIG. 1 is an external perspective view of a power generation module; FIG. FIG. 4 is an exploded perspective view of part of the module case; It is a partially enlarged view showing a joint portion of the flue gas discharge pipe of the present embodiment. It is a partially enlarged view showing a joint portion of a combustion exhaust gas discharge pipe of a comparative example. It is a partially enlarged view showing a joint portion of a flue gas discharge pipe of another embodiment.

A mode for carrying out the present invention will be described with reference to the drawings.

1 is a schematic configuration diagram of a fuel cell system including a power generation module, FIG. 2 is a schematic configuration diagram of the power generation module, FIG. 3 is an external perspective view of the power generation module, and FIG. 4 is a module case. 1 is an exploded perspective view of a portion of the . As shown in FIG. 1, the fuel cell system 20 of this embodiment includes a fuel cell stack 31 that generates power through an electrochemical reaction between hydrogen in the anode gas (fuel gas) and oxygen in the cathode gas (oxidant gas). a power generation module 30 including a power generation module 30, a raw fuel gas supply device 50 for supplying a raw fuel gas (for example, natural gas or LP gas) as a raw material of anode gas to the power generation module 30, and a raw fuel gas to the anode gas in the power generation module 30 A reformed water supply device 55 that supplies reformed water necessary for reforming, a cathode gas supply device 60 that supplies cathode gas to the power generation module 30 (fuel cell stack 31), and an output terminal of the fuel cell stack 31 are connected. A power conditioner (not shown) connected to the electric power system via a relay, an exhaust heat recovery device 70 for recovering exhaust heat generated by the power generation module 30, and a housing 21 that accommodates these and

The power generation module 30 includes a fuel cell stack 31, a vaporizer 32, and two reformers 33, which are housed in a module case 40 as the fuel cell case of this embodiment. In this embodiment, the power generation module 30 has two fuel cell stacks 31, as shown in FIG. It is installed on the manifold 34 that has been installed. Each fuel cell stack 31 has an electrolyte such as zirconium oxide and an anode electrode and a cathode electrode sandwiching the electrolyte, and a plurality of solid oxide type single cells arranged in the left-right direction (horizontal direction) in FIG. have cells. An anode gas passage (not shown) is formed in the anode electrode of each unit cell so as to extend in a direction perpendicular to the arrangement direction of the unit cells, that is, in the vertical direction. A cathode gas passage (not shown) through which cathode gas flows is formed around the cathode electrode of each unit cell so as to extend in a direction perpendicular to the arrangement direction of the unit cells, that is, in the vertical direction. The anode gas passage of each single cell communicates with the manifold 34 .

The vaporizer 32 and the reformer 33 of the power generation module 30 are arranged above the two fuel cell stacks 31 in the module case 40 with a space therebetween. In this embodiment, the vaporizer 32 and the reformer 33 are arranged above one fuel cell stack 31 , and the other reformer 33 is arranged above the other fuel cell stack 31 . Furthermore, between one fuel cell stack 31 and the vaporizer 32 and one reformer 33, and between the other fuel cell stack 31 and the other reformer 33, the operation of the fuel cell stack 31 and A combustion section 35 is defined to generate the heat necessary for the reactions in the vaporizer 32 and reformer 33 . An ignition heater 36 is installed in each combustion unit 35 .

The vaporizer 32 heats the raw fuel gas from the raw fuel gas supply device 50 and the reformed water from the reformed water supply device 55 with the heat from the combustion unit 35, preheats the raw fuel gas, and heats the reformed water. evaporate to form water vapor. The raw fuel gas preheated by the vaporizer 32 is mixed with steam, and the mixed gas flows from the vaporizer 32 into the reformer 33 . The reformer 33 has, for example, a Ru-based or Ni-based reforming catalyst filled therein, and in the presence of heat from the combustion section 35, the mixed gas from the vaporizer 32 reacts with the reforming catalyst. A (steam reforming reaction) produces hydrogen gas and carbon monoxide. Furthermore, the reformer 33 produces hydrogen gas and carbon dioxide through a reaction (carbon monoxide shift reaction) between carbon monoxide produced in the steam reforming reaction and steam. As a result, the reformer 33 generates anode gas containing hydrogen, carbon monoxide, carbon dioxide, water vapor, unreformed raw fuel gas, and the like. Anode gas generated by the reformer 33 is supplied to the anode electrode of each single cell through a pipe or manifold 34 .

Also, the cathode electrode of each unit cell of the fuel cell stack 31 is supplied with air as a cathode gas containing oxygen through a cathode gas passage 48 defined in the module case 40 . Oxide ions (O ₂ ⁻ ) are generated at the cathode electrode of each single cell, and the oxide ions permeate the electrolyte and react with hydrogen and carbon monoxide at the anode electrode to obtain electrical energy. The anode gas (hereinafter referred to as "anode off-gas") and cathode gas (hereinafter referred to as "cathode off-gas") not used for the electrochemical reaction (power generation) in each single cell are discharged from the anode gas passage and the cathode gas of each single cell. It flows out of the passage to the upper combustion section 35 .

The anode off-gas that has flowed into the combustion section 35 from each single cell is a combustible gas containing fuel components such as hydrogen and carbon monoxide, and is mixed with the oxygen-containing cathode off-gas that has flowed into the combustion section 35 from each single cell. . A mixed gas of the anode off-gas and the cathode off-gas is hereinafter referred to as "off-gas". When offgas (anode offgas) is ignited by the ignition heater 36 and ignited in the combustion unit 35, the combustion of the offgas activates the fuel cell stack 31, preheats the raw fuel gas in the vaporizer 32, and produces water vapor. Heat necessary for production, steam reforming reaction in the reformer 33, and the like is generated. In addition, combustion exhaust gas containing water vapor is generated in the combustion unit 35 as the off-gas is burned. The flue gas generated in the combustion section 35 passes through the flue gas passage 49 formed in the module case 40 and is discharged from the flue gas discharge pipe 45 to the outside of the module case 40 .

The raw fuel gas supply device 50 includes a raw fuel gas supply pipe 51 that connects the raw fuel gas supply source 10 that supplies the raw fuel gas and the vaporizer 32, and a raw fuel gas supply pipe 51 incorporated in the raw fuel gas supply pipe 51. A valve (electromagnetic on-off valve) 52, a raw fuel gas pump 53, and a desulfurizer 54 such as a room temperature desulfurization type desulfurizer 54 incorporated in the raw fuel gas supply pipe 51 so as to be positioned between the vaporizer 32 and the raw fuel gas pump 53. have. The raw fuel gas is pumped (supplied) from the raw fuel supply source 10 to the vaporizer 32 via the desulfurizer 54 by operating the raw fuel gas pump 53 .

The reforming water supply device 55 includes a reforming water tank 57 that stores reforming water, a reforming water supply pipe 56 that connects the reforming water tank 57 and the vaporizer 32, and a reforming water supply pipe 56. and a reformed water pump 58 . The reformed water in the reformed water tank 57 is pumped (supplied) to the vaporizer 32 by the reformed water pump 58 by operating the reformed water pump 58 .

The cathode gas supply device 60 has a cathode gas supply pipe 61 connected to the cathode gas passage 48 formed inside the module case 40 and a blower 62 incorporated in the cathode gas supply pipe 61 . Air as the cathode gas is pumped (supplied) from an air filter (not shown) to each fuel cell stack 31 through the cathode gas passage 48 by operating the blower 62 .

The exhaust heat recovery device 70 includes a hot water storage tank 71 for storing hot water, a heat exchanger 72 for exchanging heat between hot water and flue gas introduced from the combustion section 35 of the power generation module 30 through the flue gas passage 49, and hot water storage. It has a circulation pipe 73 connecting the tank 71 and the heat exchanger 72 and a circulation pump 74 incorporated in the circulation pipe 73 . The hot water stored in the hot water storage tank 71 is introduced into the heat exchanger 72 by operating the circulation pump 74, and after being heated in the heat exchanger 72 by heat exchange with the combustion exhaust gas, the hot water is stored. It is returned to tank 71 . Water vapor in the combustion exhaust gas is condensed by heat exchange with hot water in the heat exchanger 72, thereby obtaining condensed water.

In addition, the heat exchanger 72 (passage of combustion exhaust gas) of the exhaust heat recovery device 70 is connected to a water purifier 76 connected to the reforming water tank 57 via a pipe 75, and water vapor in the combustion exhaust gas is Condensed water obtained by condensation passes through the pipe 75 , is purified by the water purifier 76 , and is introduced into the reforming water tank 57 . Furthermore, the flue gas passage of the heat exchanger 72 is connected to a flue gas discharge pipe 77 . As a result, the exhaust gas discharged from the combustion section 35 of the power generation module 30 and from which moisture has been removed by the heat exchanger 72 is discharged into the atmosphere through the combustion exhaust gas discharge pipe 77 .

As shown in FIG. 2, the module case 40 includes a box-shaped inner case 41 having a bottom wall portion 411 formed with one through hole 411o (see FIG. 4) and an outer surface of the inner case 41 spaced apart from each other. The outer case 42 is disposed so as to cover the inner case 41 and has two through holes 421o and 421o2 (see FIG. 4) formed in the bottom wall portion 421, and one through hole 421o2 of the outer case 42 is inserted. A cathode gas introduction pipe 44 (see FIG. 3) that communicates with a cathode gas passage 48 formed between the inner case 41 and the outer case 42 and introduces the cathode gas into the cathode gas passage 48; a combustion exhaust gas discharge pipe 45 inserted through the hole 411o and the other through hole 421o of the outer case 42 and communicating with the combustion exhaust gas passage 49 defined in the inner case 41 to discharge the combustion exhaust gas from the combustion exhaust gas passage 49; have

The cathode gas passage 48 communicates with a lower passage 481 extending along the bottom surfaces of the inner case 41 and the outer case 42, and extends along side surfaces of the inner case 41 and the outer case 42 while communicating with the lower passage 481. an upper passage 483 communicating with the side passage 482 and extending along the ceiling surfaces of the inner case 41 and the outer case 42; communicating with the upper passage 483 and between the two fuel cell stacks 31; and a stack side passageway 484 extending through.

The lower passage 481 of the cathode gas passage 48 is composed of the bottom wall portion 411 of the inner case 41 extending in the horizontal direction and the bottom wall of the outer case 42 facing the bottom wall portion 411 with a gap therebetween. 421 . The lower passage 481 communicates with the cathode gas introduction pipe 44 . The cathode gas introduction pipe 44 is formed in a cylindrical shape with both ends open. are joined by welding. A cathode gas supply pipe 61 of a cathode gas supply device 60 is connected to the other open end of the cathode gas introduction pipe 44 . The side passage 482 of the cathode gas passage 48 consists of a side wall portion 412 of the inner case 41 extending in the vertical direction and a side wall portion 422 of the outer case 42 arranged to face the side wall portion 412 with a gap therebetween. formed by The upper passage 483 of the cathode gas passage 48 is composed of the upper wall portion 413 of the inner case 41 extending in the horizontal direction and the upper wall portion of the outer case 42 arranged to face the upper wall portion 413 with a gap therebetween. 423. The upper wall portion 413 of the inner case 41 is formed with an elongated opening 413o extending in the direction in which the unit cells of the fuel cell stack 31 are arranged. one end of a duct 43 is connected. The duct 43 extends vertically between the two fuel cell stacks 31 so as to form a stack-side passage 484. At the other end of the duct 43, the cathode gas that has passed through the duct 43 is supplied to the two fuel cell stacks. Apertures 43o are formed for emitting to the cathode electrodes of 31, respectively.

Also, the combustion exhaust gas passage 49 is formed in the space between the heat insulating material 39 arranged around the two fuel cell stacks 31 and the inner case 41 . The combustion exhaust gas passage 49 includes an upper passage 491 extending along the ceiling surface of the inner case 41, a side passage 492 communicating with the upper passage 491 and extending along the side surface of the inner case 41, and a side passage. 492 and a lower passage 493 extending along the bottom surface of the inner case 41 . Upper passage 491 is formed by the upper surface of heat insulating material 39 and upper wall portion 413 of inner case 41 . Side passage 492 is formed by the side surface of heat insulating material 39 and side wall portion 412 of inner case 41 . The lower passage 493 is formed by the bottom surface of the heat insulating material 39 and the bottom wall portion 411 of the inner case 41 . The lower passage 493 communicates with the flue gas discharge pipe 45 .

As shown in FIG. 5 , the flue gas discharge pipe 45 is formed in a cylindrical shape with both ends open, and one end of the flue gas discharge pipe 45 extends through a through hole 421 o formed in the bottom wall portion 421 of the outer case 42 . , and is welded along the entire periphery to the peripheral portion of a through hole 411o formed in the bottom wall portion 411 of the inner case 41 . In this embodiment, the peripheral portion of the through hole 411o is press-formed to extend inwardly of the inner case 41 in a cylindrical shape, and one end of the combustion exhaust gas discharge pipe 45 is inserted into the cylindrical portion, An edge joint is formed. The through hole 411o of the bottom wall portion 411 of the inner case 41 and the combustion exhaust gas discharge pipe 45 are joined by welding the edge joint portion by, for example, TIG (Tungsten Inert Gas) welding or laser welding. As a result, the flue gas discharge pipe 45 communicates with the flue gas passage 49 formed in the inner case 41 , and the flue gas that has passed through the flue gas passage 49 from the combustion section 35 is heated through the flue gas discharge pipe 45 . It is supplied to exchanger 72 . The combustion exhaust gas discharge pipe 45 is filled with a combustion catalyst 37 as shown in FIG.

Further, as shown in FIG. 5, the periphery of the through hole 421o of the outer case 42 (bottom wall portion 421) is formed flat, and the periphery of the through hole 411o of the inner case 41 (bottom wall portion 411) is formed flat. It is bent toward the outer case 42 side, overlapped with the periphery of the through hole 421o of the outer case 42, and is in surface contact. The circumference of the through hole 411o of the inner case 41 and the circumference of the through hole 421o of the outer case 42 are welded over the entire circumference at the surface contact portion A (the area surrounded by the dashed line in FIG. 5). is joined by In this embodiment, one of the inner case 41 and the outer case 42 is joined by penetration welding by irradiating the surface of one of the inner case 41 and the outer case 42 with a laser beam. As a result, the space between the bottom wall portion 411 of the inner case 41 and the bottom wall portion 421 of the outer case 42 around the through holes 411o and 421o, that is, the cathode gas passage 48 (lower passage 481) is airtightly formed. As a result, leakage of the cathode gas can be prevented.

Now, as shown in the comparative example of FIG. 6, the combustion exhaust gas discharge pipe 45 is welded over the entire circumference to each peripheral portion of the through hole 411o of the inner case 41 and the through hole 421Bo of the outer case 42B. Consider the case. In this case, between the outer peripheral surface of the combustion exhaust gas discharge pipe 45 and the peripheral portion of the through hole 411o of the inner case 41, and between the outer peripheral surface of the combustion exhaust gas discharge pipe 45 and the peripheral portion of the through hole 421Bo of the outer case 42B. Both through-holes 411o and 421Bo must be precisely aligned in order to prevent the formation of excessive gaps that cause poor welding. For this reason, high precision is required for processing, resulting in poor yield and increased manufacturing cost. On the other hand, in the present embodiment, the through hole 421o of the outer case 42 only needs to be formed to the extent that the combustion exhaust gas discharge pipe 45 can pass therethrough, and high precision is not required for the machining. Therefore, the inner case 41 and the outer case 42 including the through holes 411o and 421o can be manufactured at low cost.

In the fuel cell case of the present embodiment described above, the flue gas discharge pipe 45 is welded along the entire circumference to the peripheral portion of the through hole 411o formed in the bottom wall portion 411 of the inner case 41. 41 (bottom wall portion 411) and the periphery of the through hole 421o of the outer case 42 (bottom wall portion 421) are in surface contact, and the surface contact portions are joined by welding over the entire circumference. be. As a result, the space between the inner case 41 and the outer case 42 around the through holes 411o and 421o, ie, the cathode gas passage 48, can be airtightly formed, and leakage of the cathode gas can be prevented. Further, since the through-hole 421o of the outer case 42 is not directly connected to the combustion exhaust gas discharge pipe 45, it is sufficient if it is formed to the extent that the combustion exhaust gas discharge pipe 45 can pass through, and high accuracy is not required. . As a result, the through holes 411o and 421o can be formed by inexpensive press working, and the fuel cell case can be manufactured at low cost.

Further, in the fuel cell case of the present embodiment, since the surface contact portion A between the inner case 41 and the outer case 42 is joined by penetration welding, high accuracy of welding position is not required. As a result, the welding process can be easily automated, and the manufacturing cost can be further reduced.

In the embodiment, the combustion exhaust gas discharge pipe 45 is welded along the entire circumference to the peripheral portion of the through hole 411o formed in the bottom wall portion 411 of the inner case 41. The entire periphery of the annular surface contact portion A, which is in surface contact around the holes 411o and 421o, is joined by welding. However, as shown in FIG. 7, the inner case 141 and the outer case 142 are joined by welding over the entire circumference at the annular surface contact portions A that are in surface contact around the through holes 1411o and 1421o. The discharge pipe 45 may be welded to the through hole 1421o of the outer case 142 along the entire circumference.

In the embodiment, the surface contact portion A between the inner case 41 and the outer case 42 is joined by penetration welding, but may be joined by non-penetration welding.

The correspondence relationship between the main elements of the embodiments and the main elements of the invention described in the column of Means for Solving the Problems will be described. In the embodiment, the module case 40 corresponds to the "fuel cell case", the fuel cell stack 31 corresponds to the "fuel cell", the combustion section 35 corresponds to the "combustion section", and the inner case 41 corresponds to the "inner case". , the outer case 42 corresponds to the "outer case", and the combustion exhaust gas discharge pipe 45 corresponds to the "combustion exhaust gas discharge pipe".

Note that the correspondence relationship between the main elements of the embodiment and the main elements of the invention described in the column of Means for Solving the Problem indicates that the embodiment implements the invention described in the column of Means to Solve the Problem. Since it is an example for specifically explaining the mode for solving the problem, it does not limit the elements of the invention described in the column of the means for solving the problem. That is, the interpretation of the invention described in the column of Means to Solve the Problem should be made based on the description in that column, and the embodiment should be based on the description of the invention described in the column of Means to Solve the Problem. This is only a specific example.

As described above, the mode for carrying out the present invention has been described using the embodiment, but the present invention is not limited to such an embodiment at all, and various forms can be used without departing from the scope of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICABILITY The present invention is applicable to the manufacturing industry of fuel cell cases.

10 raw fuel supply source, 20 fuel cell system, 21 housing, 30 power generation module, 31 fuel cell stack, 32 vaporizer, 33 reformer, 34 manifold, 35 combustion section, 36 ignition heater, 37 combustion catalyst, 40 fuel Battery case 41, 141 Inner case 42, 42B, 142 Outer case 43 Duct 44 Cathode gas introduction pipe 45 Combustion exhaust gas discharge pipe 50 Raw fuel gas supply device 51 Raw fuel gas supply pipe 52 Raw fuel gas Supply valve 53 Raw fuel gas pump 54 Desulfurizer 55 Reformed water supply device 56 Reformed water supply pipe 57 Reformed water tank 58 Reformed water pump 60 Cathode gas supply device 61 Cathode gas supply pipe 62 blower, 70 exhaust heat recovery device, 71 hot water storage tank, 72 heat exchanger, 73 circulation pipe, 74 circulation pump, 75 pipe, 76 water purifier, 77 combustion exhaust gas discharge pipe, 411, 421 bottom wall portion, 411o, 421o , 421Bo, 1411o, 1421o through hole, 412, 422 side wall portion, 413, 423 upper wall portion, 481 lower passage, 482 side passage, 483 upper passage, 484 stack side passage, 491 upper passage, 492 side passage, 493 Lower Passage, A Face Contact Section.

Claims (3)

an inner case containing a fuel cell and a combustion section for burning off-gas from the fuel cell and having a through hole in the wall surface;
an outer case that covers the inner case with a gap from the outer surface of the inner case so as to form a predetermined gas flow path, and has a through hole in a wall surface that communicates with the through hole of the inner case;
a combustion exhaust gas discharge pipe for discharging combustion exhaust gas from the combustion unit;
with
The combustion exhaust gas discharge pipe is welded along the entire circumference to a peripheral portion of the through hole of one of the inner case and the outer case,
The inner case and the outer case have annular contact portions that contact each other around the through holes, and are joined by welding along the entire circumference of the contact portions.
fuel cell case. The fuel cell case according to claim 1,
The combustion exhaust gas discharge pipe passes through the through hole of the outer case and is welded along the entire circumference to the peripheral edge of the through hole of the inner case.
fuel cell case. 3. The fuel cell case according to claim 1 or 2,
The inner case and the outer case are joined by penetration welding at the contact portion,
fuel cell case.

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