JP6690996B2 - Electrochemical reaction cell stack - Google Patents

Description

  The technology disclosed herein relates to an electrochemical reaction cell stack.

  A solid oxide fuel cell (hereinafter referred to as “SOFC”) having an electrolyte layer containing a solid oxide is known as one of the types of fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. Has been. A fuel cell single cell (hereinafter, simply referred to as “single cell”), which is a constituent unit of SOFC, includes an electrolyte layer and air that is opposed to each other in a predetermined direction (hereinafter, referred to as “first direction”) with the electrolyte layer interposed therebetween. Including a pole and a fuel pole.

  The SOFC is generally a structure in which a plurality of single cells are arranged side by side in the first direction (hereinafter referred to as “fuel cell block”) and a pair of flat plate-shaped members that face each other in the first direction with the fuel cell block sandwiched therebetween. And a member (also called “end plate”). In the fuel cell stack, a common gas flow path (also referred to as a “manifold”) that extends over the entire fuel cell block is formed. The shared gas flow path is used for supplying a reaction gas (oxidant gas or fuel gas) to each unit cell included in the fuel cell stack and for discharging an off gas from each unit cell (for example, Patent Document 1). 1).

JP, 2005-88264, A

  In the configuration of the conventional fuel cell stack, the flat plate member is arranged in the first direction at a position overlapping with the shared gas flow path (manifold) in the first direction of one of the pair of flat plate members (end plates). A gas hole penetrating therethrough is formed. The reaction gas is supplied from a gas supply unit such as a pipe provided outside the fuel cell stack to the shared gas flow path through gas holes formed in the flat plate member. Therefore, in the configuration of the conventional fuel cell stack, there is a problem that the temperature of the reaction gas supplied to the shared gas flow channel is not sufficiently high, and as a result, the power generation performance is not sufficiently high. Further, in the configuration of the conventional fuel cell stack, the configuration of the gas pipes provided outside the fuel cell stack becomes large and complicated, and as a result, the fuel pipes and the gas pipes outside the fuel cell stack are provided. There is a problem in that the configuration of the module including is large and complicated.

  It should be noted that such a problem is that the electrolytic single cell, which is a constituent unit of a solid oxide electrolytic cell (hereinafter, referred to as “SOEC”) that generates hydrogen by utilizing an electrolysis reaction of water, has a first direction. This is also a common problem in an electrolysis cell stack including a plurality of electrolysis cell blocks arranged side by side. In this specification, the fuel cell stack and the electrolytic cell stack are collectively referred to as "electrochemical reaction cell stack". Further, such a problem is not limited to SOFC and SOEC, but is common to other types of electrochemical reaction cell stacks.

  This specification discloses a technique capable of solving the above-mentioned problems.

  The technology disclosed in the present specification can be implemented, for example, in the following modes.

(1) The electrochemical reaction cell stack disclosed in the present specification is an electrochemical reaction single cell that includes an electrolyte layer and an air electrode and a fuel electrode that face each other in the first direction with the electrolyte layer interposed therebetween. A plurality of electrochemical reaction blocks arranged side by side in the first direction, and a plurality of flat plates arranged side by side in the first direction at a position on one side of the electrochemical reaction block in the first direction. An electrochemical reaction cell stack in which a shared gas flow channel extending across the electrochemical reaction block is formed, the member being located at the one end in the first direction of the plurality of flat plate-shaped members. On the outer surface that is the one side surface of the outer flat plate member that is the flat plate member, a gas hole is formed at a position that does not overlap the shared gas flow path in the first direction view, The interior of a structure constituted by the serial plurality of plate-like member, communicates a gas flow path communicating with said common gas flow path and the gas hole is formed. In this electrochemical reaction cell stack, the reaction gas introduced into the electrochemical reaction cell stack from the outside flows into the communication gas flow path from the gas holes provided in the outer flat plate-shaped member, and then flows into the common gas flow path. To do. When the reaction gas passes through the communication gas channel, the temperature of the reaction gas rises due to the heat from the electrochemical reaction single cell. Therefore, according to the present electrochemical reaction cell stack, the temperature of the reaction gas flowing into the shared gas flow channel can be controlled as compared with the configuration in which the reaction gas directly flows into the shared gas flow channel from outside the electrochemical reaction cell stack. It can be increased, and the reaction efficiency of power generation and hydrogen generation can be improved, and as a result, the performance of the electrochemical reaction cell stack can be improved. Further, in the present electrochemical reaction cell stack, since the communication gas flow path is formed inside the structure composed of a plurality of flat plate-shaped members, the length of the pipe outside the electrochemical reaction cell stack is shortened. As a result, the module including the electrochemical reaction cell stack and the gas pipe outside the electrochemical reaction cell stack can be downsized and the configuration can be simplified.

(2) In the electrochemical reaction cell stack, on the one side in the first direction of the structure constituted by the flat plate member excluding the outer flat plate member of the plurality of flat plate members, A first recessed portion that forms a communication gas flow path is formed, and the gas hole of the outer flat plate-shaped member is arranged at a position overlapping the first recessed portion when viewed in the first direction, and A portion of the first recess that does not overlap the gas hole may be closed by the outer flat plate member. According to the present electrochemical reaction cell stack, it is possible to form the communicating gas flow channel inside the structure constituted by the plurality of flat plate-shaped members while suppressing the increase in the thickness of the outer flat plate-shaped member. Further, according to the present electrochemical reaction cell stack, since the shape of the communication gas flow channel can be easily changed, it is possible to improve the degree of freedom of arrangement of gas pipes connected to the electrochemical reaction cell stack.

(3) In the electrochemical reaction cell stack, a first welding mark is formed on the outer surface of the outer flat plate member along a first imaginary line that surrounds the communication gas passage in the first direction. May be formed. According to the present electrochemical reaction cell stack, it is possible to enhance the sealing property of the communication gas flow passage and suppress gas leakage from the communication gas flow passage.

(4) In the electrochemical reaction cell stack, a second recess is formed on the outer surface of the outer flat plate-like member, and at least a part of the first welding mark is the second recess. It may be configured to be formed in. According to the present electrochemical reaction cell stack, it is possible to prevent the first welding mark from protruding beyond the outer surface of the outer flat plate-shaped member.

(5) In the electrochemical reaction cell stack, at least a part of the first welding mark formed in the second recess may be separated from the side surface of the second recess. According to the present electrochemical reaction cell stack, the contact portion between the first welding mark and the outer flat plate-shaped member can be reduced, so that metal diffusion between the two can be suppressed, and problems such as deterioration of durability occur. Occurrence can be suppressed.

(6) In the electrochemical reaction cell stack, at least a part of the first welding mark formed in the second recess may be in contact with a side surface of the second recess. According to the present electrochemical reaction cell stack, the width of the first welding mark can be widened and the bondability between the outer flat plate member and the other flat plate member can be improved.

(7) In the electrochemical reaction cell stack, in the first direction, the shape of the outer flat plate-shaped member is a second virtual line which is an outer peripheral line of a minimum virtual rectangular region including the outer flat plate-shaped member. An intersection of a line and a third virtual line that is a virtual straight line orthogonal to a part of the first virtual line is defined as a first point, and the third virtual line and the outer periphery of the outer flat plate-shaped member The point closest to the first point among the intersections with the line is the second point, and the point closest to the first point among the intersections with the third virtual line and the first virtual line. When the point is the third point, the second point may satisfy a specific condition including the condition defined by the following equation (1), and the second point may be present.
L ₂₃ <L ₁₃ (1)
(However, L ₁₃ is the distance between the first point and the third point, and L ₂₃ is the distance between the second point and the third point.)
According to the present electrochemical reaction cell stack, the portion of the outer flat plate-like member outside the first welding mark can be made smaller in the first direction, so that the portion may undergo thermal expansion or deformation, for example. It is possible to reduce the stress generated in the first welding mark at the time of performing, and it is possible to suppress the occurrence of gas leakage from the communication gas flow path due to the separation in the first welding mark.

(8) In the above electrochemical reaction cell stack, the specific condition may include a condition defined by the following formula (2).
L ₂₃ ≦ L ₁₃ × 3/4 (2)
According to the present electrochemical reaction cell stack, the portion of the outer flat plate-like member outside the first welding mark can be made smaller in the first direction, so that the stress generated in the first welding mark is effective. Therefore, it is possible to effectively reduce the occurrence of gas leakage from the communication gas flow path due to separation at the first welding mark.

(9) In the electrochemical reaction cell stack, in the first direction, the shape of the outer flat plate-shaped member is such that the second point is within a predetermined length in the outer peripheral line of the outer flat plate-shaped member. The configuration may be such that the specific condition is always satisfied when According to this electrochemical reaction cell stack, the portion of the outer flat plate member corresponding to the range of the predetermined length on the outer peripheral line can be made smaller than the first welding mark on the outer flat plate member. Therefore, it is possible to reduce the stress generated in the first welding mark in a wide range, and it is possible to effectively suppress the occurrence of gas leakage from the communication gas flow path due to the separation in the first welding mark.

(10) In the electrochemical reaction cell stack, the predetermined length may be ¼ or more of the length of the virtual rectangular region in the direction parallel to the outer peripheral line within the range. According to the present electrochemical reaction cell stack, since the outer flat plate member can be made smaller than the first welding mark in the portion corresponding to the relatively long range in the outer peripheral line of the outer flat plate member, It is possible to reduce the stress generated in the first welding mark in a wide range, and it is possible to effectively suppress the occurrence of gas leakage from the communicating gas flow path due to the separation in the first welding mark.

(11) In the electrochemical reaction cell stack, the outer flat plate-like member has a third recess in the outer peripheral line of the outer flat plate-like member as viewed in the first direction, and The configuration may be such that the specific condition is satisfied when the second point is in the third recess. The third concave portion on the outer peripheral line of the outer flat plate-shaped member is a portion where the stress generated in the first welding mark is likely to become large. Since the portion of the flat plate member outside the first welding mark can be made smaller, the stress generated in the first welding mark can be reduced, and the stress from the first welding mark can be reduced from the communicating gas flow path. Generation of gas leakage can be suppressed.

(12) The electrochemical reaction cell stack further includes a bolt screwed to at least one of two convex portions sandwiching the third concave portion in the outer flat plate-shaped member when viewed in the first direction. It may be configured. In the outer flat plate-shaped member, if a bolt is screwed into each of the two convex portions sandwiching the third concave portion, the stress generated in the first welding mark is likely to be further increased. According to this structure, since the portion of the outer flat plate member outside the first welding mark can be made smaller, the stress generated in the first welding mark can be reduced, and the first welding mark can be reduced. It is possible to suppress the occurrence of gas leakage from the communicating gas flow path due to separation at the mark.

(13) In the electrochemical reaction cell stack, a second welding mark is formed on the outer surface of the outer flat plate member between the second point and the third point satisfying the specific condition. It may be configured to be. If the second welding mark is formed between the second point and the third point satisfying the specific condition on the outer surface of the outer flat plate-like member, the stress generated in the first welding mark is further increased. However, according to the present electrochemical reaction cell stack, in such a structure, the portion of the outer flat plate-like member outside the first welding mark can be made smaller, so that the stress generated in the first welding mark can be reduced. Can be reduced, and the occurrence of gas leakage from the communication gas passage due to peeling at the first welding mark can be suppressed.

(14) In the electrochemical reaction cell stack, in the first direction, the first welding mark has a fourth intersection point at the other intersection of the second virtual line and the third virtual line. In such a case, the structure may be formed so as to satisfy the condition defined by the following expression (3).
L ₁₃ ≧ L ₁₄ × 1/8 (3)
(However, L ₁₄ is the distance between the first point and the fourth point.)
When the distance between the first point and the third point is relatively long, the stress generated in the first welding mark is likely to be further increased. However, according to the present electrochemical reaction cell stack, in such a configuration, Since the portion of the outer flat plate-shaped member outside the first welding mark can be made smaller, the stress generated in the first welding mark can be reduced, and the communication gas flow path due to the separation at the first welding mark It is possible to suppress the occurrence of gas leakage from the inside.

(15) In the electrochemical reaction cell stack, the outer flat plate member and the adjacent flat plate member that is the flat plate member adjacent to the outer flat plate member among the plurality of flat plate members are thermally expanded. The rates may be different from each other. When the outer flat plate member and the adjacent flat plate member have different coefficients of thermal expansion, the stress generated in the first welding mark tends to increase. However, according to the present electrochemical reaction cell stack, in such a structure, Since the portion of the flat plate member outside the first welding mark can be made smaller, the stress generated in the first welding mark can be reduced, and the stress from the first welding mark can be reduced from the communicating gas flow path. Generation of gas leakage can be suppressed.

(16) In the electrochemical reaction cell stack, as viewed in the first direction, at least a part of a side of an outer peripheral line of the outer flat plate-shaped member which is parallel to a second direction orthogonal to the first direction. , A position of at least a part of a side orthogonal to the first direction and parallel to a third direction which is not parallel to the second direction is set to the outer flat plate-shaped member among the plurality of flat plate-shaped members. A configuration may be adopted in which the position coincides with the position of the fourth virtual line that is the outer peripheral line of the smallest virtual rectangular region that includes the adjacent flat plate-shaped member that is the adjacent flat plate-shaped member. According to the present electrochemical reaction cell stack, it is possible to reduce the portion of the outer flat plate member outside the first welding mark while suppressing a decrease in the accuracy of the position of the outer flat plate member. The stress generated in the scar can be reduced.

(17) In the electrochemical reaction cell stack, the side parallel to the second direction and the side parallel to the third direction of the outer peripheral line of the outer flat plate-shaped member in the first direction. At least one of the sides is a portion located inside the outer peripheral line of the adjacent flat plate-shaped member and a portion located inside the outer peripheral line of the adjacent flat plate-shaped member sandwiched between the two, which are coincident with the position of the outer peripheral line of the adjacent flat plate-shaped member. A part may be included. According to the present electrochemical reaction cell stack, it is possible to reduce the position of the outer flat plate-shaped member more effectively, and to reduce the outer portion of the outer flat plate-shaped member from the first welding mark, The stress generated in the first welding mark can be reduced.

(18) In the electrochemical reaction cell stack, the outer flat plate-shaped member includes a plurality of flat plate-shaped members including a first outer flat plate-shaped member and a second outer flat plate-shaped member that are spaced apart from each other. Inside the structure constituted by a member, the first communication gas flow passage that connects the gas hole formed in the first outer flat plate-shaped member and one common gas flow passage, and A second communication gas flow passage that connects the gas hole formed in the second outer flat plate member and the other common gas flow passage is formed, and the first outer flat plate member is formed. The first welding mark may be formed on the outer surface of each of the second outer flat plate member. According to the present electrochemical reaction cell stack, the portion of each outer flat plate-like member outside the first welding mark can be made smaller in the first direction, so that the stress generated in the first welding mark is reduced. Therefore, it is possible to suppress the occurrence of gas leakage from the communication gas flow path due to the separation at the first welding mark.

(19) In the electrochemical reaction cell stack, one of the first communication gas flow path and the second communication gas flow path is one of the plurality of flat plate-shaped members when viewed in the first direction. The adjacent flat plate member, which is the flat plate member adjacent to the outer flat plate member, is arranged so as to overlap with one end region when divided into three regions in a predetermined direction, and the first communication is performed. The other of the gas flow passage and the second communication gas flow passage is in the other end region when the adjacent flat plate-shaped member is divided into three regions in the predetermined direction in the first direction view. It may be configured to be arranged so as to overlap. One of the first communication gas flow passage and the second communication gas flow passage is arranged so as to overlap with one end region when the adjacent flat plate-shaped member is divided into three regions in a predetermined direction, and the other. Is arranged so as to overlap the other end region when the adjacent flat plate-shaped member is divided into three regions in a predetermined direction, the number of outer flat plate-shaped members provided in the electrochemical reaction cell stack is 1 If there are only one, the portion outside the first welding mark on the outer flat plate-shaped member tends to be large. According to the present electrochemical reaction cell stack, since the electrochemical reaction cell stack includes the first outer flat plate-shaped member and the second outer flat plate-shaped member that are arranged apart from each other, The portion outside the first welding mark can be made smaller, the stress generated in the first welding mark can be reduced, and the occurrence of gas leakage from the communicating gas flow path due to separation at the first welding mark can be suppressed. can do.

  The technology disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction cell stack (fuel cell stack or electrolysis cell stack), an electrochemical reaction cell stack and gas piping, etc. It is possible to realize it in the form of an electrochemical reaction module including and a method for manufacturing them.

FIG. 3 is a perspective view showing an external configuration of a fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the YZ cross section structure of the fuel cell stack 100 in the position of II-II of FIG. It is explanatory drawing which shows the YZ cross section structure of the fuel cell stack 100 in the position of III-III of FIG. It is explanatory drawing which shows the XZ cross-section structure of the fuel cell stack 100 in the position of IV-IV of FIG. FIG. 6 is a perspective view showing an external configuration of each of a lower end plate 106 and a cover plate 200. It is an explanatory view showing the composition of the lower surface (XY plane) of the lower end plate 106. It is an explanatory view showing the composition of the lower surface (XY plane) of cover plate 200. It is explanatory drawing which shows the XZ cross-section structure of the cover plate 200 and the end plate 106 in the position of VIII-VIII of FIG. 6 and FIG. It is explanatory drawing which shows the structure of the lower surface (XY plane) of the cover plate 200 in the 1st modification of 1st Embodiment. It is explanatory drawing which shows the XZ cross-section structure of the cover plate 200 vicinity in the 2nd modification of 1st Embodiment. It is explanatory drawing which shows the structure of the lower surface (XY plane) of the lower end plate 106 in the fuel cell stack 100 of 2nd Embodiment. It is explanatory drawing which shows the structure of the lower surface (XY plane) of the cover plate 200 in the fuel cell stack 100 of 2nd Embodiment.

A. First embodiment:
A-1. Constitution:
(Configuration of Fuel Cell Stack 100)
FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment, and FIG. 2 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 at a position II-II in FIG. 3 is an explanatory diagram showing a YZ sectional structure of the fuel cell stack 100 at the position III-III in FIG. 1, and FIG. 4 shows an XZ sectional structure of the fuel cell stack 100 at the position IV-IV in FIG. It is an explanatory view shown. In each drawing, XYZ axes which are orthogonal to each other for specifying the directions are shown. In the present specification, for convenience, the Z-axis positive direction is referred to as the upward direction, and the Z-axis negative direction is referred to as the downward direction, but the fuel cell stack 100 is actually different from such an orientation. It may be installed. Further, in this specification, a direction orthogonal to the Z axis (for example, the X direction or the Y direction) is referred to as a surface direction.

  As shown in FIGS. 2 to 4, the fuel cell stack 100 is installed via columns 20 in a heat insulating container 10 in which a heat insulating material is provided on the inner side surface of a housing made of, for example, stainless steel.

  Further, below the fuel cell stack 100, an auxiliary device 40 that is responsible for intake and exhaust of the fuel cell stack 100 and the like is arranged. Various pipes 70 extending from the outside of the heat insulating container 10 are connected to the auxiliary device 40, and the oxidant gas OG, the raw fuel gas, the reforming water, and the like are introduced into the auxiliary device 40 via the pipe 70. At the same time, the exhaust gas is discharged from the auxiliary device 40. Inside the auxiliary device 40, a reforming chamber for reforming the raw fuel gas to generate the fuel gas FG and a combustion chamber for burning off gas discharged from the fuel cell stack 100 are formed. Further, various pipes 60 are provided between the auxiliary device 40 and the fuel cell stack 100, and the oxidant gas OG and the fuel gas FG are supplied from the auxiliary device 40 to the fuel cell stack 100 via the pipes 60. Is introduced, and off gas is discharged from the fuel cell stack 100 to the auxiliary device 40.

  As shown in FIGS. 1 to 4, the fuel cell stack 100 includes a plurality of (seven in the present embodiment) fuel cell power generation units (hereinafter, simply referred to as “power generation units”) 102 and a pair of end plates 104 and 106. And a cover plate 200. The plurality of power generation units 102 included in the fuel cell stack 100 are arranged side by side in a predetermined array direction (the vertical direction in the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an assembly (hereinafter referred to as “power generation block 103”) composed of a plurality of power generation units 102 from above and below. Further, the cover plate 200 is arranged below the lower end plate 106. The arrangement direction (vertical direction) corresponds to the first direction in the claims, and the power generation block 103 corresponds to the electrochemical reaction block in the claims.

  As shown in FIG. 1 and FIG. 4, a plurality of (eight in this embodiment) holes penetrating in the vertical direction are formed in the peripheral portions of the power generation units 102 and the end plates 104, 106 around the Z direction. The holes formed in each of the power generation units 102 and the end plates 104, 106 correspond to each other in the vertical direction, and extend in the vertical direction from one end plate 104 to the other end plate 106. It constitutes 108. In the following description, a hole formed in each member to form the fastening communication hole 108 may also be referred to as the fastening communication hole 108.

  Bolts 22 extending in the vertical direction are inserted into the respective fastening communication holes 108, and each power generation unit 102 and each end plate 104, 106 are integrally formed by the bolts 22 and the nuts 24 fitted at both ends of the bolts 22. It has been concluded. In addition, between the nut 24 fitted on the upper side of each bolt 22 and the upper surface of the upper end plate 104, and on the lower side of the nut 24 fitted on the lower side of each bolt 22 and the lower end plate 106. An insulating sheet 26 is interposed between the surface and the surface. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust sheet, a glass sheet, a glass-ceramic composite agent or the like.

  Further, as shown in FIGS. 1 to 3, a plurality of (four in the present embodiment) holes penetrating in the vertical direction are formed in the peripheral portion of each power generation unit 102 around the Z direction, and each power generation unit Corresponding holes formed in the unit 102 communicate with each other in the up-down direction to form a flow path communication hole 109 extending in the up-down direction over an assembly (power generation block 103) including a plurality of power generation units 102. . In the following description, the holes formed in each power generation unit 102 to configure the flow passage communication hole 109 may also be referred to as the flow passage communication hole 109.

  As shown in FIGS. 1 and 2, located near the midpoint of one side (the Y-axis positive direction side of the two sides parallel to the X-axis) on the Z-direction outer periphery of the fuel cell stack 100. The flow path communication hole 109 that functions as an oxidant gas introduction manifold 161 that is a gas flow path that supplies the oxidant gas OG introduced into the fuel cell stack 100 to the air chamber 166 of each power generation unit 102 The flow path communication hole 109 located near the midpoint of the opposite side (the Y-axis negative direction side of the two sides parallel to the X-axis) is discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidant gas discharge manifold 162 which is a gas flow path for discharging the oxidant off-gas OOG which is the generated gas to the outside of the fuel cell stack 100. In this embodiment, for example, air is used as the oxidant gas OG.

  In addition, as shown in FIGS. 1 and 3, near the midpoint of one side (the side on the Y axis negative direction side of the two sides parallel to the X axis) on the outer periphery of the fuel cell stack 100 around the Z direction. The communication hole 109 for the flow path located at the position functions as a fuel gas introduction manifold 171 which is a gas flow path for supplying the fuel gas FG introduced into the fuel cell stack 100 to the fuel chamber 176 of each power generation unit 102, The flow path communication hole 109 located near the midpoint of the opposite side (the Y-axis positive direction side of the two sides parallel to the X-axis) is discharged from the fuel chamber 176 of each power generation unit 102. It functions as a fuel gas discharge manifold 172 which is a gas flow path for discharging the fuel off-gas FOG which is the generated gas to the outside of the fuel cell stack 100. In this embodiment, as the fuel gas FG, for example, hydrogen-rich gas obtained by reforming city gas is used. The manifolds 161, 162, 171, 172 correspond to the common gas flow passage in the claims.

(Structure of End Plates 104, 106 and Cover Plate 200)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. The upper end plate 104 is arranged above the power generation block 103 composed of a plurality of power generation units 102, and the lower end plate 106 is arranged below the power generation block 103. A plurality of power generation units 102 are sandwiched by a pair of end plates 104 and 106 in a pressed state. In the present embodiment, the upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

  The cover plate 200 is a flat plate-shaped conductive member, and is made of, for example, stainless steel. The cover plate 200 is arranged adjacent to the lower side of the lower end plate 106.

In the present embodiment, the material forming the cover plate 200 is different from the material forming the lower end plate 106. For example, the lower end plate 106 is formed of ferritic stainless steel (for example, SUS430, SUS434, SUS405, SUS444, etc.), and the cover plate 200 is austenitic stainless steel (for example, SUS201, SUS301, SUS305, SUS304, SUS316, etc.). Therefore, the thermal expansion coefficient of the cover plate 200 is different from the thermal expansion coefficient of the lower end plate 106. More specifically, the coefficient of thermal expansion of the cover plate 200 is greater than the coefficient of thermal expansion of the lower end plate 106. For example, the coefficient of thermal expansion at 700 (° C.) of the cover plate 200 is 11.0 × 10 ^{−6 to} 13.5 × 10 ⁻⁶ (/ ° C.), and the coefficient of thermal expansion at 700 (° C.) of the lower end plate 106. The coefficient of thermal expansion is 11.0 × 10 ^{−6 to} 13.5 × 10 ⁻⁶ (/ ° C.). Further, in the present embodiment, the thickness of the cover plate 200 is smaller than the thickness of the lower end plate 106 in order to improve the workability and reduce the weight. For example, the cover plate 200 has a thickness of 0.1 to 3 (mm), and the lower end plate 106 has a thickness of 5 to 12 (mm). Due to at least one of the relationship of the coefficient of thermal expansion and the relationship of the thickness described above, the cover plate 200 is more likely to be thermally expanded than the lower end plate 106.

  As described above, the lower end plate 106 and the cover plate 200 are arranged side by side in the Z direction at a position on one side (lower side) in the Z direction with respect to the power generation block 103 including the plurality of power generation units 102. It is a plurality of flat plate-shaped members. The cover plate 200 is a flat plate-shaped member located at the end on the one side (lower side) in the Z direction among the plurality of flat plate-shaped members, and corresponds to the outer flat plate-shaped member in the claims. Further, the lower end plate 106 is a flat plate-shaped member that is adjacent to the cover plate 200 among the plurality of flat plate-shaped members, and corresponds to an adjacent flat plate-shaped member in the claims. The configurations of the lower end plate 106 and the cover plate 200 will be described in detail later.

(Configuration of power generation unit 102)
As shown in FIGS. 2 to 4, a power generation unit 102, which is the minimum unit of power generation, includes a fuel cell single cell (hereinafter simply referred to as “single cell”) 110, a separator 120, an air electrode side frame 130, and an air The electrode-side current collector 134, the fuel-electrode-side frame 140, the fuel-electrode-side current collector 144, and the pair of interconnectors 150 forming the uppermost layer and the lowermost layer of the power generation unit 102 are provided. The separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150 are provided with holes corresponding to the above-described fastening communication holes 108 and flow path communication holes 109 at the peripheral edges in the Z direction. There is. Since the power generation unit 102 includes the single cell 110, the above-described power generation block 103 can also be expressed as a structure in which a plurality of single cells 110 are arranged side by side in the vertical direction.

  The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector 150 secures electrical continuity between the power generation units 102 and prevents reaction gas from mixing between the power generation units 102. In this embodiment, when the two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by the two adjacent power generation units 102. That is, the upper interconnector 150 in a certain power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since the fuel cell stack 100 includes the pair of end plates 104 and 106, the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150, but located at the bottom. The power generation unit 102 does not include the lower interconnector 150.

  The unit cell 110 includes an electrolyte layer 112, and an air electrode (cathode) 114 and a fuel electrode (anode) 116 that face each other in the up-down direction (the arrangement direction of the power generation units 102) with the electrolyte layer 112 interposed therebetween. The unit cell 110 of this embodiment is a fuel electrode-supporting unit cell in which the fuel electrode 116 supports the electrolyte layer 112 and the air electrode 114.

  The electrolyte layer 112 is a substantially rectangular plate-shaped member, and includes, for example, YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxide. It is formed of a solid oxide such as. The air electrode 114 is a substantially rectangular plate-shaped member, and is formed of, for example, a perovskite type oxide (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). Has been done. The fuel electrode 116 is a substantially rectangular flat plate-shaped member, and is formed of, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like. As described above, the unit cell 110 (power generation unit 102) of the present embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte.

  The separator 120 is a frame-shaped member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. The peripheral portion of the hole 121 in the separator 120 faces the peripheral portion of the surface of the electrolyte layer 112 on the air electrode 114 side. The separator 120 is joined to the unit cell 110 by a joining portion formed of a brazing material (for example, Ag brazing material) arranged in the facing portion. The separator 120 separates an air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116, and gas leakage from one electrode side to the other electrode side in the peripheral portion of the unit cell 110 is prevented. Suppressed.

 The air electrode side frame 130 is a frame-shaped member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of an insulator such as mica. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. The air electrode side frame 130 is in contact with the peripheral edge portion of the surface of the separator 120 opposite to the side facing the single cell 110 and the peripheral edge portion of the surface of the interconnector 150 facing the air electrode 114. . The air electrode side frame 130 electrically insulates between the pair of interconnectors 150 included in the power generation unit 102. As shown in FIG. 2, the air electrode side frame 130 is provided with an oxidant gas supply communication hole 132 for communicating the oxidant gas introduction manifold 161 and the air chamber 166, an air chamber 166 and an oxidant gas discharge manifold 162. An oxidant gas discharge communication hole 133 that communicates is formed.

  The fuel electrode side frame 140 is a frame-shaped member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The hole 141 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the separator 120 facing the single cell 110 and the peripheral portion of the surface of the interconnector 150 facing the fuel electrode 116. As shown in FIG. 3, in the fuel electrode side frame 140, a fuel gas supply communication hole 142 that connects the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel that connects the fuel chamber 176 and the fuel gas discharge manifold 172. A gas discharge communication hole 143 is formed.

  The fuel electrode side current collector 144 is arranged in the fuel chamber 176. The fuel electrode side current collector 144 is made of, for example, nickel, a nickel alloy, stainless steel, or the like. The fuel electrode side current collector 144 is in contact with the surface of the fuel electrode 116 opposite to the surface facing the electrolyte layer 112 and the surface of the interconnector 150 facing the fuel electrode 116. However, as described above, the lowermost power generation unit 102 in the fuel cell stack 100 does not include the lower interconnector 150. Therefore, the fuel electrode side current collector 144 in the power generation unit 102 is disposed on the lower side. It is in contact with the end plate 106. Since the fuel electrode side current collector 144 has such a configuration, the fuel electrode 116 and the interconnector 150 (or the end plate 106) are electrically connected. In each power generation unit 102, the fuel electrode side current collector 144 and the lower interconnector 150 may be an integral member.

  The air electrode side current collector 134 is arranged in the air chamber 166. The air electrode side current collector 134 is made of, for example, ferritic stainless steel. The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 facing the air electrode 114. However, as described above, since the uppermost power generation unit 102 in the fuel cell stack 100 does not include the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 is the upper end plate. It is in contact with 104. Since the air electrode side current collector 134 has such a configuration, it electrically connects the air electrode 114 and the interconnector 150 (or the end plate 104). In addition, in each power generation unit 102, the air electrode side current collector 134 and the upper interconnector 150 may be an integral member.

(Structures of Lower End Plate 106 and Cover Plate 200)
FIG. 5 is a perspective view showing the external configurations of the lower end plate 106 and the cover plate 200, and FIG. 6 is an explanatory diagram showing the configuration of the lower surface (XY plane) of the lower end plate 106. 7A and 7B are explanatory views showing the configuration of the lower surface (XY plane) of the cover plate 200. Note that, in FIG. 6, the position of the cover plate 200 is shown by a broken line so as to overlap with the configuration of the lower end plate 106. Similarly, in FIG. 7, the position of the lower end plate 106 is shown by a broken line, overlapping the configuration of the cover plate 200.

  As described above, eight fastening communication holes 108 that penetrate the lower end plate 106 in the vertical direction are formed in the peripheral portion of the lower end plate 106 around the Z direction. Further, on the lower surface of the lower end plate 106, four flow path recesses (grooves) 107 extending in the surface direction (Y direction) are formed. The flow path recess 107 corresponds to the first recess in the claims. Further, at the position of each flow path recess 107, a flow path through hole 105 is formed to vertically penetrate the lower end plate 106. As shown in FIGS. 2 and 3, the flow passage through-holes 105 formed at the positions of the four flow passage recesses 107 respectively include an oxidant gas introduction manifold 161, an oxidant gas discharge manifold 162, and a fuel gas introduction. The manifold 171 and the fuel gas discharge manifold 172 are arranged at positions overlapping with each other when viewed in the Z direction, and communicate with the manifolds that overlap with each other when viewed in the Z direction.

  As shown in FIGS. 5 to 7, the outer peripheral shape of the cover plate 200 as viewed in the Z direction is at a position overlapping the outer peripheral shape of the lower end plate 106 with the fastening communication hole 108, that is, four corners and It has a shape in which a notch (outer shape concave portion Pa) is formed at a position substantially in the center of each side. Further, the cover plate 200 is formed with four gas holes 202 penetrating the cover plate 200 in the vertical direction. The four gas holes 202 correspond to the four flow path recesses 107 formed in the lower end plate 106. Each gas hole 202 overlaps with the corresponding flow channel recess 107 and does not overlap with each manifold 161, 162, 171, 172 (that is, a position that does not overlap the flow channel through hole 105) when viewed in the Z direction. It is located in. In the state where the cover plate 200 is arranged on the lower surface of the lower end plate 106, the portion of each flow path recess 107 that does not overlap with the gas hole 202 is closed by the cover plate 200. Therefore, a space constituted by the flow path recesses 107 is secured inside the structure constituted by the cover plate 200 and the lower end plate 106. This space is opened to the outside of the fuel cell stack 100 through the gas holes 202 and communicates with the corresponding manifolds 161, 162, 171, 172 through the passage through holes 105. That is, the space formed by the flow path recesses 107 forms communication gas flow paths that connect the gas holes 202 and the manifolds 161, 162, 171, 172. Hereinafter, the communication gas flow path communicating with the oxidant gas introduction manifold 161 is referred to as an oxidant gas introduction communication flow path 163, and the communication gas flow path communicating with the oxidant gas discharge manifold 162 is referred to as an oxidant gas discharge communication flow path. A communication gas flow path communicating with the fuel gas introduction manifold 171 is called a fuel gas introduction communication flow path 173, and a communication gas flow path communicating with the fuel gas discharge manifold 172 is called a fuel gas discharge communication flow path 174. .

  As shown in FIG. 2, a pipe 60 for introducing the oxidant gas OG from the auxiliary device 40 is connected to the oxidant gas introduction communication channel 163, and the oxidant gas discharge communication channel 164 is connected to the pipe 60. A pipe 60 for discharging the oxidant off-gas OOG to the auxiliary device 40 is connected. Further, as shown in FIG. 3, a pipe 60 for introducing the fuel gas FG from the auxiliary device 40 is connected to the fuel gas introduction communication flow path 173, and the fuel gas discharge communication flow path 174 is connected to the fuel gas discharge communication flow path 174. A pipe 60 for discharging the offgas FOG to the auxiliary device 40 is connected.

  As shown in FIGS. 5 to 7, the cover plate 200 is joined to the lower end plate 106 by welding. More specifically, on the lower surface of the cover plate 200, an outer peripheral welding mark 220 that joins the cover plate 200 and the lower end plate 106 is formed along the vicinity of the outer peripheral line OL of the cover plate 200 when viewed in the Z direction. ing. Further, on the lower surface of the cover plate 200, welding for a flow path that joins the cover plate 200 and the lower end plate 106 along the first imaginary line VL1 that surrounds each flow path recess 107 when viewed in the Z direction. A scar 210 is formed. As a result, the communication gas flow paths (oxidant gas introduction communication flow path 163, oxidant gas discharge communication flow path 164, fuel gas introduction communication flow path 173, fuel gas discharge communication flow) formed by the flow path recesses 107 are formed. The sealing of the passage 174) is enhanced. The flow path welding mark 210 corresponds to the first welding mark in the claims, and the outer peripheral welding mark 220 corresponds to the second welding mark in the claims.

  As shown in FIG. 8 showing the XZ sectional configuration at the position of VIII-VIII in FIGS. 6 and 7, a welding recess 230 is formed on the lower surface (Z-axis negative direction side) of the cover plate 200. The outer peripheral welding mark 220 and the flow path welding mark 210 are formed in the welding recess 230. Further, the outer peripheral welding mark 220 and the flow path welding mark 210 are separated from the side surface of the welding recess 230. The welding recess 230 corresponds to the second recess in the claims.

(Details of the shape of the cover plate 200, etc.)
The shape of the cover plate 200 and the like will be described in more detail. The details of the shape of the cover plate 200 and the like will be described below with reference to the following lines and points when viewed in the Z direction (see FIG. 7).
-First virtual line VL1 (described above): Line for forming flow path welding mark 210-Second virtual line VL2: Outer peripheral line of the smallest virtual rectangular area including cover plate 200-Third virtual line VL3 : Virtual straight line orthogonal to a part of the first virtual line VL1 ・ Fourth virtual line VL4: Outer peripheral line of the smallest virtual rectangular area including the lower end plate 106 ・ First point P1: Second One point of intersection between the virtual line VL2 and the third virtual line VL3 / second point P2: closest to the first point P1 of the intersection points between the third virtual line VL3 and the outer peripheral line OL of the cover plate 200. Point-Third point P3: Point closest to the first point P1 among the intersections of the third virtual line VL3 and the first virtual line VL1. Fourth point P4: Second virtual line VL2. The other intersection with the third virtual line VL3

  As described above, when viewed from the Z direction, the outer peripheral shape of the cover plate 200 is such that the outer shape recessed portions Pa are formed at four corners and substantially central portions of the respective sides with respect to the outer peripheral shape of the lower end plate 106. It has a curved shape. In the following, among the outer shape concave portions Pa on the outer peripheral line OL of the cover plate 200, attention is paid to the outer shape concave portion Pa having a width L1 and a depth L2 formed at a position substantially at the center of the left side of the outer periphery of the end plate 106 in FIG. The shape of the cover plate 200 will be described. However, the same can be said with respect to the other outer shape concave portions Pa formed on the cover plate 200. The outer shape recess Pa corresponds to the third recess in the claims.

As shown in FIG. 7, in the present embodiment, when viewed from the Z direction, the shape of the cover plate 200 has a second point P2 that satisfies the specific condition SC including the condition defined by the following equation (1). It is a shape to do. In this formula (1), at the second point P2, the outer peripheral line OL of the cover plate 200 recedes inward from the second virtual line VL2 which is the outer peripheral line of the smallest virtual rectangular area including the cover plate 200. It means that In the present embodiment, for example, since the outer shape recess Pa is formed in the cover plate 200, the formula (1) is satisfied when the second point P2 is on the line defining the outer shape recess Pa. The length of one side of the second virtual line VL2 is, for example, 140 to 220 (mm).
L ₂₃ <L ₁₃ (1)
(However, L ₁₃ is the distance between the first point P1 and the third point P3, and L ₂₃ is the distance between the second point P2 and the third point P3.)

  Further, in the present embodiment, as viewed in the Z direction, the shape of the cover plate 200 is such that the second point P2 is in the range of the predetermined length L1 on the outer peripheral line OL of the cover plate 200, specifically, the outer shape concave portion Pa. The shape is such that the specific condition SC is always satisfied when it is on the bottom side BL. In the present embodiment, the predetermined length L1 is the virtual rectangular region (first direction) in the direction (Y direction in the example of FIG. 7) parallel to the outer peripheral line OL (that is, the bottom side BL of the outer shape recess Pa) within the range. It is 1/4 or more of the length of the area surrounded by the virtual line VL2.

  In the present embodiment, the position of the side portion Sy1 which is at least a part of the side parallel to the second direction (Y direction, for example) orthogonal to the Z direction in the outer peripheral line OL of the cover plate 200 in the Z direction. And a position of a side portion Sx1 that is at least a part of a side that is orthogonal to the Z direction and that is parallel to the third direction (for example, the X direction) that is not parallel to the second direction, of the fourth virtual line VL4. It matches the position.

  Further, in the present embodiment, the side parallel to the second direction (for example, the Y direction) of the outer peripheral line OL of the cover plate 200 when viewed in the Z direction is located inside the outer peripheral line of the end plate 106. And the two side portions Sy1 which are located on both sides of the side portion Sy2 and which coincide with the position of the outer peripheral line of the end plate 106. Similarly, in the present embodiment, the side parallel to the third direction (for example, the X direction) of the outer peripheral line OL of the cover plate 200 is located inside the outer peripheral line of the end plate 106 when viewed in the Z direction. It includes a side portion Sx2, which is a portion, and two side portions Sx1 that sandwich the side portion Sx2 and coincide with the position of the outer peripheral line of the end plate 106.

  Further, in the present embodiment, the outer peripheral welding mark 220 is formed on the lower surface of the cover plate 200 between the second point P2 and the third point P3 that satisfy the specific condition SC.

Further, in the present embodiment, the flow path welding mark 210 is formed so as to satisfy the condition defined by the following expression (3) when viewed in the Z direction.
L ₁₃ ≧ L ₁₄ × 1/8 (3)
(However, L ₁₄ is the distance between the first point P1 and the fourth point P4.)

A-2. Operation of the fuel cell stack 100:
As shown in FIG. 2, the oxidant gas OG introduced into the auxiliary device 40 via the pipe 70 outside the heat insulating container 10 is an oxidation gas provided in the fuel cell stack 100 from the auxiliary device 40 via the pipe 60. It is introduced into the agent gas introduction communication channel 163. The oxidant gas OG introduced into the oxidant gas introduction communication channel 163 is supplied from the oxidant gas introduction communication channel 163 to the oxidant gas introduction manifold 161, and the oxidant gas introduction manifold 161 oxidizes each power generation unit 102. It is supplied to the air chamber 166 through the agent gas supply communication hole 132. Further, as shown in FIGS. 2 and 3, when the raw fuel gas or the reforming water is introduced into the auxiliary device 40 through the pipe 70 outside the heat insulating container 10, the raw fuel gas is reformed in the reforming chamber of the auxiliary device 40. The gas is reformed to generate the fuel gas FG, and the generated fuel gas FG is introduced into the fuel gas introduction communication channel 173 provided in the fuel cell stack 100 via the pipe 60. The fuel gas FG introduced into the fuel gas introduction communication passage 173 is supplied to the fuel gas introduction manifold 171 from the fuel gas introduction communication passage 173, and the fuel gas supply passage hole 142 of each power generation unit 102 is supplied from the fuel gas introduction manifold 171. Is supplied to the fuel chamber 176 via.

  When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, oxygen contained in the oxidant gas OG and hydrogen contained in the fuel gas FG in the single cell 110. Power is generated by an electrochemical reaction with. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to one interconnector 150 (or the upper end plate 104) via the air electrode side current collector 134, and the fuel electrode 116 is the fuel electrode. It is electrically connected to the other interconnector 150 (or the lower end plate 106) via the side current collector 144. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates power at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is heated by a heater ( It may be heated by (not shown).

  As shown in FIG. 2, the oxidant off-gas OOG discharged from the air chamber 166 to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication hole 133 of each power generation unit 102 is oxidized from the oxidant gas discharge manifold 162. It is discharged to the agent gas discharge communication channel 164 and then discharged from the oxidant gas discharge communication channel 164 to the auxiliary device 40 via the pipe 60 outside the fuel cell stack 100. Further, as shown in FIG. 3, the fuel off-gas FOG discharged from the fuel chamber 176 to the fuel gas discharge manifold 172 through the fuel gas discharge communication hole 143 of each power generation unit 102 is discharged from the fuel gas discharge manifold 172. It is discharged to the communication channel 174, and is discharged from the fuel gas discharge communication channel 174 to the auxiliary device 40 via the pipe 60 outside the fuel cell stack 100. The oxidant offgas OOG and the fuel offgas FOG discharged to the auxiliary device 40 are mixed and burned in the fuel chamber provided in the auxiliary device 40, and are discharged to the outside of the heat insulating container 10 through the pipe 70.

A-3. Effects of this embodiment:
As described above, in the fuel cell stack 100 of the present embodiment, the power generation block 103 in which a plurality of single cells 110 (power generation units 102) are arranged side by side in the vertical direction, and one side in the vertical direction of the power generation block 103 ( The end plate 106, which is a plurality of flat plate-shaped members, and the cover plate 200, which are arranged side by side in the vertical direction, are provided at the (lower side) position. Further, in the fuel cell stack 100, each manifold 161, 162, 171, 172 which is a common gas flow path extending over the power generation block 103 is formed. Further, in the end plate 106 and the cover plate 200, which are the plurality of flat plate-shaped members, in the cover plate 200 (outer flat plate-shaped member), which is a flat plate-shaped member located at the end on the one side (lower side) in the vertical direction. Gas holes 202 are formed on the surface of the one side (lower side) at positions that do not overlap the manifolds 161, 162, 171, 172 when viewed in the Z direction. Further, inside the structure constituted by the plurality of flat plate-shaped members (end plate 106 and cover plate 200), gas holes 202 provided on the lower surface of the cover plate 200 and the manifolds 161, 162, 171, 172 are provided. Communication gas passages (oxidant gas introduction communication passage 163, oxidant gas discharge communication passage 164, fuel gas introduction communication passage 173, fuel gas discharge communication passage 174) are formed. Therefore, in the fuel cell stack 100 of the present embodiment, the oxidant gas OG and the fuel gas FG introduced into the fuel cell stack 100 via the pipe 60 end from the gas holes 202 provided on the lower surface of the cover plate 200. It flows into each communication gas passage (oxidant gas introduction communication passage 163 and fuel gas introduction communication passage 173) formed inside the structure constituted by the plate 106 and the cover plate 200, and then each manifold ( It flows into the oxidant gas introduction manifold 161 and the fuel gas introduction manifold 171). As described above, since the power generation reaction in each unit cell 110 is an exothermic reaction, heat from the unit cell 110 is generated when the oxidant gas OG and the fuel gas FG pass through the communication gas passages 163 and 173. As a result, the temperatures of the oxidant gas OG and the fuel gas FG rise. Therefore, according to the fuel cell stack 100 of the present embodiment, as compared with the configuration in which the oxidant gas OG and the fuel gas FG directly flow into the manifolds 161, 171 from the outside of the fuel cell stack 100, each manifold 161, The temperatures of the oxidant gas OG and the fuel gas FG flowing into 171 can be increased, the reaction efficiency of power generation in each single cell 110 can be improved, and as a result, the power generation performance of the fuel cell stack 100 can be improved. be able to. Further, in the fuel cell stack 100 of the present embodiment, the communication gas flow paths 163, 164, 173, 174 are formed inside the structure constituted by the end plate 106 and the cover plate 200. The length of the pipe 60 outside the 100 can be shortened, and as a result, the module including the fuel cell stack 100 and the gas pipe outside the fuel cell stack 100 can be downsized and the configuration can be simplified. You can

  Further, in the fuel cell stack 100 of the present embodiment, a structure formed by the flat plate-shaped members excluding the cover plate 200, which is the outer flat plate-shaped member, among the plurality of flat plate-shaped end plates 106 and the cover plate 200. (That is, the above-mentioned one side (lower side) of the end plate 106), the flow path recessed portion 107 that constitutes each communication gas flow path 163, 164, 173, 174 is formed, and the gas hole 202 of the cover plate 200. Are arranged at positions overlapping the corresponding channel recesses 107 when viewed in the Z direction, and the portions of the channel recesses 107 that do not overlap the gas holes 202 are blocked by the cover plate 200. Therefore, according to the fuel cell stack 100 of the present embodiment, each communication gas flow channel 163 is provided inside the structure constituted by the cover plate 200 and the end plate 106 while suppressing an increase in the thickness of the cover plate 200. 164, 173, 174 can be formed.

  Further, in the fuel cell stack 100 of the present embodiment, flow path welding is performed on the lower surface of the cover plate 200 along the first imaginary line VL1 surrounding each of the communicating gas flow paths 163, 164, 173, 174 when viewed in the Z direction. A scar 210 is formed. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to enhance the sealing property of each of the communication gas flow paths 163, 164, 173, 174, and the gas from each of the communication gas flow paths 163, 164, 173, 174. Leakage can be suppressed.

  Further, in the fuel cell stack 100 of the present embodiment, a welding recess 230 is formed on the lower surface of the cover plate 200, and the flow path welding mark 210 is formed in the welding recess 230. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to suppress the flow path welding mark 210 from protruding beyond the lower surface of the cover plate 200. Similarly, in the fuel cell stack 100 of the present embodiment, the outer peripheral welding mark 220 is also formed in the welding recess 230, so that the outer peripheral welding mark 220 can be prevented from protruding beyond the lower surface of the cover plate 200. .

  Further, in the fuel cell stack 100 of this embodiment, the flow path welding mark 210 formed in the welding recess 230 is separated from the side surface of the welding recess 230. Therefore, according to the fuel cell stack 100 of the present embodiment, the number of contact points between the flow path welding mark 210 and the cover plate 200 can be reduced, so that metal diffusion between the two can be suppressed and the durability is reduced. It is possible to suppress the occurrence of such problems. Similarly, in the fuel cell stack 100 of the present embodiment, since the outer peripheral welding mark 220 formed in the welding recess 230 is separated from the side surface of the welding recess 230, the outer peripheral welding mark 220 and the cover plate 200 are separated from each other. Since the number of contact points can be reduced, metal diffusion between the two can be suppressed, and problems such as reduced durability can be suppressed.

Further, in the fuel cell stack 100 of the present embodiment, the shape of the cover plate 200 has a second point P2 that satisfies the specific condition SC including the condition defined by the following formula (1) when viewed in the Z direction. It is a shape to do.
L ₂₃ <L ₁₃ (1)
(However, L ₁₃ is the distance between the first point P1 and the third point P3, and L ₂₃ is the distance between the second point P2 and the third point P3.)
Therefore, according to the fuel cell stack 100 of the present embodiment, at the second point P2, the outer peripheral line OL of the cover plate 200 is the second virtual line that is the outer peripheral line of the smallest virtual rectangular region including the cover plate 200. By retreating inward from the line VL2, the portion of the cover plate 200 outside the flow path welding mark 210 can be made smaller, so that the flow path welding is performed, for example, when the portion undergoes thermal expansion or deformation. The stress generated in the trace 210 can be reduced, and the occurrence of gas leakage from each of the communication gas flow channels 163, 164, 173, 174 due to the separation in the flow channel welding trace 210 can be suppressed.

In addition, it is preferable that the specific condition includes a condition defined by the following expression (2).
L ₂₃ ≦ L ₁₃ × 3/4 (2)
With this configuration, the portion of the cover plate 200 outside the flow path welding mark 210 can be made smaller as viewed in the Z direction, so that the stress generated in the flow path welding mark 210 can be effectively reduced. Therefore, it is possible to effectively suppress the occurrence of gas leakage from each of the communication gas flow paths 163, 164, 173, and 174 due to the separation in the flow path welding mark 210.

Further, in order to reduce the stress generated in the flow path welding mark 210 _effectively, more preferably _{L 23} is less than 1/2 of the _{L 13,} it _{L 23} is less than 1/3 of the _{L 13} Is more preferable, and L ₂₃ is more preferably 1/4 or less of L ₁₃ .

  Further, in the fuel cell stack 100 of the present embodiment, when viewed from the Z direction, the shape of the cover plate 200 is such that the second point P2 is in the range of the predetermined length L1 on the outer peripheral line OL of the cover plate 200, specifically, The shape is such that the specific condition SC is always satisfied when it is on the bottom side BL of the outer shape recess Pa. Therefore, according to the fuel cell stack 100 of the present embodiment, a portion of the outer peripheral line OL of the cover plate 200 that corresponds to the range of the predetermined length L1 is a portion outside the flow path welding mark 210 of the cover plate 200. Since it is possible to reduce the stress, it is possible to reduce the stress generated in the flow path welding mark 210 in a wide range, and the gas from each of the communication gas flow paths 163, 164, 173, 174 due to the separation in the flow path welding mark 210. It is possible to effectively suppress the occurrence of leakage. In the present embodiment, the predetermined length L1 is ¼ or more of the length of the virtual rectangular area (the area surrounded by the second virtual line VL2) in the direction parallel to the outer peripheral line OL within the range. Is. Therefore, according to the fuel cell stack 100 of the present embodiment, in the portion corresponding to the relatively long range in the outer peripheral line OL of the cover plate 200, the portion of the cover plate 200 outside the flow path welding mark 210 is made smaller. Therefore, the stress generated in the flow path welding mark 210 can be further reduced in a wide range, and gas leakage from the communication gas flow paths 163, 164, 173, 174 due to separation in the flow path welding mark 210 occurs. Can be suppressed more effectively.

  Further, in the fuel cell stack 100 of the present embodiment, as viewed in the Z direction, the shape of the cover plate 200 is such that the outer peripheral recess Pa exists on the outer peripheral line OL of the cover plate 200, and the second point P2 is the outer peripheral recess Pa. The shape satisfies the specific condition SC when The portion of the outer peripheral recess Pa on the outer peripheral line OL of the cover plate 200 is a portion where the stress generated in the flow path welding trace 210 is likely to be large, but according to the fuel cell stack 100 of the present embodiment, in such a portion. Since the portion of the cover plate 200 outside the flow path welding mark 210 can be made smaller, the stress generated in the flow path welding mark 210 can be reduced, and each communication due to peeling in the flow path welding mark 210 can be achieved. Generation of gas leakage from the gas flow paths 163, 164, 173, 174 can be suppressed.

  Further, in the fuel cell stack 100 of the present embodiment, the outer peripheral welding mark 220 is formed on the lower surface of the cover plate 200 between the second point P2 and the third point P3 that satisfy the specific condition SC. There is. When the outer peripheral welding mark 220 is formed on the lower surface of the cover plate 200 between the second point P2 and the third point P3 that satisfy the specific condition SC, the stress generated in the flow path welding mark 210 is generated. The fuel cell stack 100 according to the present embodiment is likely to become larger, but in such a configuration, the portion outside the flow path welding mark 210 in the cover plate 200 can be made smaller, so that flow path welding is possible. It is possible to reduce the stress generated in the trace 210, and it is possible to suppress the occurrence of gas leakage from each of the communicating gas flow channels 163, 164, 173, 174 due to the separation in the flow channel welding trace 210.

Further, in the fuel cell stack 100 of this embodiment, the flow path welding mark 210 is formed so as to satisfy the condition defined by the following formula (3) when viewed in the Z direction.
L ₁₃ ≧ L ₁₄ × 1/8 (3)
(However, L ₁₄ is the distance between the first point P1 and the fourth point P4.)
When the distance between the first point P1 and the third point P3 is relatively long, the stress generated in the flow path welding mark 210 is likely to be further increased. However, according to the fuel cell stack 100 of the present embodiment, In such a configuration, since the portion of the cover plate 200 outside the flow path welding mark 210 can be made smaller, the stress generated in the flow path welding mark 210 can be reduced, and the flow path welding mark 210 can be reduced. It is possible to suppress the occurrence of gas leakage from each of the communication gas flow paths 163, 164, 173, 174 due to the separation in the above.

Further, in order to reduce the stress generated in the flow path welding mark 210 _effectively, more preferably _{L 13} is 1/4 or more of _{L 14,} it _{L 13} is 1/3 or more of _{L 14} Is more preferable, and L ₁₃ is more preferably 1/2 or more of L ₁₄ .

  Further, in the fuel cell stack 100 of this embodiment, the cover plate 200 and the lower end plate 106 have different coefficients of thermal expansion. When the thermal expansion coefficients of the cover plate 200 and the lower end plate 106 are different from each other, the stress generated in the flow path welding mark 210 is likely to be large due to the thermal expansion difference between the cover plate 200 and the lower end plate 106, but in the fuel cell stack 100 of the present embodiment. According to this structure, the portion of the cover plate 200 outside the flow path welding mark 210 can be made smaller, so that the stress generated in the flow path welding mark 210 can be reduced and the flow path welding mark 210 can be reduced. It is possible to suppress the occurrence of gas leakage from the communication gas flow paths 163, 164, 173, 174 due to the peeling at the welding mark 210.

  Further, in the fuel cell stack 100 of the present embodiment, as viewed in the Z direction, it is at least a part of a side of the outer peripheral line OL of the cover plate 200 that is parallel to the second direction (for example, the Y direction) orthogonal to the Z direction. The position of the side portion Sy1 and the position of the side portion Sx1 which is at least a part of the side orthogonal to the Z direction and parallel to the third direction (eg, the X direction) that is not parallel to the second direction are the fourth position. Coincides with the position of the virtual line VL4. Therefore, according to the fuel cell stack 100 of the present embodiment, at the position of the side portion Sy1 and the position of the side portion Sx1, the direction orthogonal to the second direction of the cover plate 200 with respect to the lower end plate 106 and the third direction. It is possible to perform positioning in a direction orthogonal to the direction, and it is possible to reduce a portion of the cover plate 200 outside the flow path welding mark 210 while suppressing deterioration of the position accuracy of the cover plate 200. It is possible to reduce the stress generated in the welding trace 210 for welding, and as a result, it is possible to suppress the occurrence of gas leakage from each of the communicating gas flow passages 163, 164, 173, 174 due to separation in the welding trace 210 for flow passage. . It is preferable that the second direction and the third direction are substantially orthogonal to each other because the cover plate 200 can be positioned more accurately.

  Further, in the fuel cell stack 100 of the present embodiment, the side parallel to the second direction (for example, the Y direction) of the outer peripheral line OL of the cover plate 200 when viewed from the Z direction is closer to the outer peripheral line of the end plate 106. It includes a side portion Sy2 which is a portion located inside, and two side portions Sy1 which sandwich the side portion Sy2 located inside thereof and which coincide with the position of the outer peripheral line of the end plate 106. Similarly, in the fuel cell stack 100 of the present embodiment, a side parallel to the third direction (for example, the X direction) of the outer peripheral line OL of the cover plate 200 when viewed in the Z direction is the outer peripheral line of the end plate 106. It includes a side portion Sx2 which is a portion located on the inner side and two side portions Sx1 which sandwich the side portion Sx2 located on the inner side and which coincide with the position of the outer peripheral line of the end plate 106. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to more effectively suppress a decrease in the accuracy of the position of the cover plate 200 with respect to the lower end plate 106, and to use the flow path welding traces 210 in the cover plate 200 as compared with the welding marks 210. The outer portion can be made smaller, and the stress generated in the flow path welding mark 210 can be reduced. As a result, the respective communication gas flow paths 163, 164, 173, 174 due to the separation in the flow path welding mark 210. It is possible to suppress the occurrence of gas leakage from the inside.

A-4. Performance evaluation:
Performance evaluation was performed on the fuel cell stack 100 using the cover plates 200 of the examples and the comparative examples. The structure of the cover plate 200 of the embodiment is as shown in FIG. 7, the width L1 of the outer shape recess Pa is 72 (mm), and the depth L2 of the outer shape recess Pa is 20.5 (mm). It was Further, the configuration of the cover plate 200 of the comparative example is different from that of the example in that the outer shape concave portion Pa is not provided. With respect to the fuel cell stack 100 using the cover plates 200 of the example and the comparative example, the stress generated in the flow path welding mark 210 at the position of the third point P3 shown in FIG. 7 was calculated using SIM. The fuel cell stack 100 using the cover plate 200 of the comparative example had a stress of 20 to 35 (MPa), whereas the fuel cell stack 100 using the cover plate 200 of the example had a stress of 5 to 15 (MPa). (MPa). As described above, it was confirmed that the stress generated in the flow path weld mark 210 can be significantly reduced by providing the outer recess Pa on the cover plate 200.

  Further, when the fuel cell stack 100 using the cover plate 200 of the example and the comparative example was actually prepared and heat treatment was performed, in the fuel cell stack 100 using the cover plate 200 of the comparative example, the communication gas flow channel 163 was formed. , 164, 173, 174 were confirmed, but in the fuel cell stack 100 using the cover plate 200 of the example, no gas leakage was confirmed from the communication gas flow paths 163, 164, 173, 174. It was As described above, by providing the external recess Pa in the cover plate 200, the stress generated in the flow path welding mark 210 can be significantly reduced, and as a result, the gas leakage from the communication gas flow paths 163, 164, 173, 174 can be prevented. It was confirmed that the generation could be suppressed.

A-5. First modification of the first embodiment:
FIG. 9 is an explanatory diagram showing the configuration of the lower surface (XY plane) of the cover plate 200 in the first modified example of the first embodiment. In the fuel cell stack 100 of the first modified example of the first embodiment shown in FIG. 9, in the cover plate 200, at least one of the two protrusions Pb sandwiching the outer shape recess Pa in the Z direction, for example, the cover plate 200 and Bolts 204 for joining the end plate 106 are screwed together. In the first modified example of the first embodiment, since the bolt 204 is screwed into at least one of the two convex portions Pb that sandwich the external concave portion Pa in the cover plate 200, the stress generated in the flow path welding trace 210 is generated. More likely to grow. However, also in the first modified example of the first embodiment, since the configuration of the cover plate 200 is the same as that of the above-described first embodiment, the portion of the cover plate 200 outside the flow path welding mark 210 is removed. It is possible to reduce the size, reduce the stress generated in the flow path welding mark 210, and suppress the occurrence of gas leakage from the communicating gas flow paths 163, 164, 173, 174 due to separation in the flow path welding mark 210. can do.

A-6. Second modification of the first embodiment:
FIG. 10 is an explanatory diagram showing an XZ sectional configuration in the vicinity of the cover plate 200 in the second modified example of the first embodiment. FIG. 10 shows an XZ sectional configuration near the cover plate 200 of the second modified example of the first embodiment at a position corresponding to the XZ sectional configuration of the first embodiment shown in FIG. 8 described above. In the second modified example of the first embodiment, similarly to the above-described first embodiment, the welding recess 230 is formed on the surface on the lower side (Z-axis negative direction side) of the cover plate 200, and the outer peripheral welding is performed. The trace 220 and the flow path welding trace 210 are formed in the welding recess 230. However, in the second modification of the first embodiment, the outer peripheral welding mark 220 and the flow path welding mark 210 are in contact with the side surface of the welding recess 230. Therefore, according to the second modified example of the first embodiment, as compared with the configuration in which the outer peripheral welding trace 220 and the flow channel welding trace 210 are separated from the side surface of the welding recess 230, the flow channel welding is performed. The width of the trace 210 and the peripheral welding mark 220 can be increased, and the bondability between the cover plate 200 and the end plate 106 can be improved.

B. Second embodiment:
FIG. 11 is an explanatory view showing the configuration of the lower surface (XY plane) of the lower end plate 106 in the fuel cell stack 100 of the second embodiment, and FIG. 12 is a cover of the fuel cell stack 100 of the second embodiment. FIG. 6 is an explanatory diagram showing a configuration of a lower surface (XY plane) of the plate 200. In the following, among the configurations of the fuel cell stack 100 of the second embodiment, the same configurations as the configurations of the fuel cell stack 100 of the first embodiment described above will be denoted by the same reference numerals and the description thereof will be appropriately omitted. .

  As shown in FIGS. 11 and 12, in the second embodiment, the cover plate 200 is composed of a first cover plate 200a and a second cover plate 200b that are spaced apart from each other. The first cover plate 200a is arranged so as to cover a region on the Y axis negative direction side of the end plate 106 when viewed in the Z direction, and the second cover plate 200b is disposed in the Z direction when viewed from the end plate 106. It is arranged so as to cover the region on the Y axis positive direction side, and the end plate 106 is not covered by the cover plate 200 in the region between the first cover plate 200a and the second cover plate 200b in the Y direction. Exposed. The first cover plate 200a corresponds to the first outer flat plate member in the claims, and the second cover plate 200b corresponds to the second outer flat plate member in the claims.

  Also in the fuel cell stack 100 of the second embodiment, as in the first embodiment, four flow path recesses (in the second embodiment, the X direction) extending in the surface direction (X direction in the second embodiment) are formed on the lower surface of the lower end plate 106. A groove portion) 107 is formed, and a flow path through hole 105 that vertically penetrates the lower end plate 106 is formed at the position of each flow path concave portion 107. Are arranged at positions overlapping the corresponding manifolds 161, 162, 171, 172 when viewed in the Z direction, and communicate with the manifolds that overlap when viewed in the Z direction.

  Further, the first cover plate 200a is formed with two gas holes 202 penetrating the first cover plate 200a in the vertical direction, and each gas hole 202 is for a corresponding flow path when viewed in the Z direction. It is arranged at a position that overlaps the recess 107 and does not overlap the manifolds 161, 162, 171, 172. In a state where the first cover plate 200a is arranged on the lower surface of the lower end plate 106, a portion of each flow path recess 107 that does not overlap with the gas hole 202 is closed by the first cover plate 200a. Therefore, a communication gas flow path (oxidant gas discharge communication flow path 164 and oxidant gas discharge communication flow path 164 and The fuel gas introduction communication channel 173) is secured. In the present embodiment, the oxidant gas discharge communication flow path 164 and the fuel gas introduction communication flow path 173 are substantially equal to each other when the lower end plate 106 is divided into three regions in the Y direction when viewed in the Z direction. It is arranged so as to overlap with one end region (the uppermost region in the example shown in FIG. 12). At least one of the oxidant gas discharge communication channel 164 and the fuel gas introduction communication channel 173 corresponds to the first communication gas channel in the claims.

  Similarly, the second cover plate 200b is formed with two gas holes 202 penetrating the second cover plate 200b in the vertical direction, and each gas hole 202 has a corresponding flow path when viewed in the Z direction. It is arranged at a position that overlaps with the recessed portion 107 and does not overlap with each of the manifolds 161, 162, 171, 172. In the state where the second cover plate 200b is arranged on the lower surface of the lower end plate 106, a portion of each flow path recess 107 that does not overlap with the gas hole 202 is closed by the second cover plate 200b. Therefore, a communication gas flow path (oxidant gas introduction communication flow path 163 and oxidant gas introduction communication flow path 163, which is formed by the flow path recesses 107, is provided inside the structure including the second cover plate 200b and the lower end plate 106. A fuel gas discharge communication channel 174) is secured. In the present embodiment, the oxidant gas introduction communication flow channel 163 and the fuel gas discharge communication flow channel 174 are formed by dividing the lower end plate 106 into three regions in the Y direction in a substantially equal manner when viewed in the Z direction. It is arranged so as to overlap the other end region (the lowermost region in the example shown in FIG. 12). At least one of the oxidant gas introduction communication passage 163 and the fuel gas discharge communication passage 174 corresponds to the second communication gas passage in the claims.

  An outer peripheral weld mark 220 is formed on the lower surface of the first cover plate 200a along the vicinity of the outer peripheral line OL of the first cover plate 200a when viewed in the Z direction, and the flow path recesses are formed when viewed in the Z direction. A welding trace 210 for a flow path is formed along a first imaginary line VL1 that surrounds 107. As a result, the sealability of the communication gas flow paths (the oxidant gas discharge communication flow path 164 and the fuel gas introduction communication flow path 173) formed by the flow path recesses 107 is improved.

  Similarly, on the lower surface of the second cover plate 200b, an outer peripheral welding mark 220 is formed along the vicinity of the outer peripheral line OL of the second cover plate 200b when viewed in the Z direction, and each flow when viewed in the Z direction. A flow path welding mark 210 is formed along a first virtual line VL1 surrounding the road recess 107. As a result, the sealability of the communication gas flow paths (oxidant gas introduction communication flow path 163 and fuel gas discharge communication flow path 174) formed by the flow path recesses 107 is improved.

  Note that, also in the fuel cell stack 100 of the second embodiment, as in the first embodiment, with respect to each of the first cover plate 200a and the second cover plate 200b, the outer peripheral line of the cover plate 200 when viewed in the Z direction. A position of a side portion Sy1 that is at least a part of a side parallel to a second direction (for example, the Y direction) that is orthogonal to the Z direction in the OL and a position that is orthogonal to the Z direction and is not parallel to the second direction. The position of the side portion Sx1, which is at least a part of the side parallel to the direction 3 (for example, the X direction), is the outer peripheral line of the smallest virtual rectangular area including the lower end plate 106 (the fourth virtual line VL4). It matches the position of.

  Further, also in the fuel cell stack 100 of the second embodiment, as in the first embodiment, the outer peripheral line of the cover plate 200 is viewed in the Z direction for each of the first cover plate 200a and the second cover plate 200b. A side of the OL parallel to the third direction (for example, the X direction) is a side portion Sx2 that is a portion located inside the outer peripheral line of the end plate 106, and an outer periphery of the end plate 106 that sandwiches the side portion Sx2. It includes two side portions Sx1 that coincide with the position of the line.

  As described above, the fuel cell stack 100 of the second embodiment has the following actions and effects in addition to the actions and effects of the fuel cell stack 100 of the first embodiment described above. In the fuel cell stack 100 of the second embodiment, the cover plate 200 includes a first cover plate 200a and a second cover plate 200b that are arranged apart from each other. Further, gas holes formed in the first cover plate 200a are provided inside the structure constituted by the cover plate 200 (the first cover plate 200a and the second cover plate 200b) and the lower end plate 106. A communication gas flow path (oxidant gas discharge communication flow path 164 and fuel gas introduction communication flow path 173) that connects 202 and the manifold (oxidant gas discharge manifold 162 and fuel gas introduction manifold 171), and a second cover plate A communication gas flow path (oxidant gas introduction communication flow path 163 and fuel gas discharge communication flow path) that connects the gas hole 202 formed in 200b to another manifold (oxidant gas introduction manifold 161 and fuel gas discharge manifold 172). 174) are formed. In addition, a flow path welding mark 210 is formed on the lower surface of each of the first cover plate 200a and the second cover plate 200b. Therefore, according to the fuel cell stack 100 of the second embodiment, when viewed in the Z direction, the portions of the first cover plate 200a and the second cover plate 200b outside the flow path welding mark 210 are made smaller. Therefore, the stress generated in the flow path welding mark 210 can be reduced, and the occurrence of gas leakage from each communicating gas flow path 163, 164, 173, 174 due to the separation in the flow path welding mark 210 can be suppressed. be able to.

  Further, in the fuel cell stack 100 of the second embodiment, a part of the communication gas flow path (the oxidant gas discharge communication flow path 164 and the fuel gas introduction communication flow path 173) has a lower end plate 106 when viewed in the Z direction. Is arranged so as to overlap with an end region on the Y-axis negative direction side when the region is divided into three regions in a predetermined direction (Y direction in the example shown in FIG. 12) in a substantially equal manner. A part (oxidant gas introduction communication flow path 163 and fuel gas discharge communication flow path 174) is in the Y axis positive direction when the lower end plate 106 is divided into the above three regions in a substantially equal manner when viewed in the Z direction. It is arranged so as to overlap the end region on the side. A part of the communication gas flow channel is arranged so as to overlap with one end region of the three regions, and another part of the communication gas flow channel is disposed with the other end region of the three regions. When the fuel cell stack 100 is provided with only one cover plate 200 when the fuel cell stack 100 and the fuel cell stack 100 are arranged so as to overlap with each other, a portion of the cover plate 200 outside the flow path welding mark 210 tends to be large. According to the fuel cell stack 100 of the second embodiment, the fuel cell stack 100 includes the first cover plate 200a and the second cover plate 200b that are arranged apart from each other, and therefore, for the flow path in each cover plate 200. The portion outside the welding trace 210 can be made smaller, the stress generated in the flow passage welding trace 210 can be reduced, and the peeling at the flow passage welding trace 210 can be achieved. The occurrence of gas leakage from the communication gas channel 163,164,173,174 can be suppressed by.

C. Other variants:
The technique disclosed in this specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof, for example, the following modifications are also possible.

  The configuration of the fuel cell stack 100 in the above embodiment is merely an example, and can be variously modified. For example, in the above embodiment, the communication gas flow paths 163, 164, 173, 174 are formed by forming the flow path recesses 107 in the end plate 106, but instead of the end plate 106, or In addition to the end plate 106, similar communication channel recesses may be formed in the cover plate 200 to form the communication gas channels 163, 164, 173, 174.

  Further, in the above-described embodiment, the communication gas flow paths 163, 164, 173, 174 are formed inside the structure constituted by the two flat plate members, that is, the end plate 106 and the cover plate 200. Each communication gas flow path 163, 164, 173, 174 may be formed inside the structure constituted by three or more flat plate members. For example, in the above-described embodiment, the end plate 106 is composed of a plurality of flat plate-shaped members, and the communication gas flow paths are provided inside the structure composed of the plurality of flat plate-shaped members of the end plate 106 and the cover plate 200. 163, 164, 173, 174 may be formed. In this case, a vertical through hole is formed in one or more of the plurality of flat plate-shaped members constituting the end plate 106, and the side of the through hole facing the power generation block 103 constitutes the end plate 106. The through holes may function as the communication gas passages 163, 164, 173, 174 by being blocked by another flat plate-shaped member.

  Further, at least a part of each of the communication gas flow paths 163, 164, 173, 174 may be formed on the upper side of the fuel cell stack 100. For example, a cover plate may be arranged on the upper surface of the upper end plate 104, and a communication gas channel may be formed inside the structure constituted by the upper end plate 104 and the cover plate. Further, it is not necessary that all of the communication gas passages 163, 164, 173, 174 be formed in the fuel cell stack 100, and at least one communication gas passage may be formed.

  Further, in the above-described embodiment, the flow passage communication hole 109 is provided separately from the fastening communication hole 108, but at least one of the fastening communication holes 108 provided in the fuel cell stack 100 is used for the flow passage. It may also function as the communication hole 109.

  Further, in the above embodiment, the entire flow path welding trace 210 and the outer peripheral welding trace 220 are formed in the welding recess 230, but only a part of the flow channel welding trace 210 and the outer peripheral welding trace 220 are formed. It may be formed in the welding recess 230. Further, in the first embodiment described above, the entire flow path welding mark 210 and the outer peripheral welding mark 220 formed in the welding recess 230 are separated from the side surface of the welding recess 230, but the flow path welding is performed. Only part of the trace 210 or the outer peripheral welding trace 220 may be separated from the side surface of the welding recess 230. However, when the entire flow path welding trace 210 and the outer peripheral welding trace 220 are separated from the side surface of the welding recess 230, metal diffusion between the two is well suppressed and the deterioration of durability is effectively suppressed. It is possible to do so, which is preferable.

  Similarly, in the first modification of the first embodiment, the entire flow path welding mark 210 and the outer peripheral welding mark 220 formed in the welding recess 230 are in contact with the side surface of the welding recess 230. However, only a part of the flow path welding mark 210 or the peripheral welding mark 220 may be in contact with the side surface of the welding recess 230. However, if the entire flow path welding trace 210 and the outer peripheral welding trace 220 are in contact with the side surface of the welding recess 230, the width can be expanded over the entire flow channel welding trace 210 and the outer peripheral welding trace 220, and the cover can be formed. This is preferable because the bondability between the plate 200 and the end plate 106 can be improved satisfactorily.

  It should be noted that some of the flow path welding traces 210 and the outer peripheral welding traces 220 are separated from the side surfaces of the welding recesses 230, and the rest of the flow channel welding traces 210 and the peripheral welding marks 220 are the welding recesses 230. If it is in contact with the side surface of the cover plate 200, it is possible to improve the bondability between the cover plate 200 and the end plate 106 while suppressing deterioration in durability.

  Further, in the above embodiment, at least one of the flow path welding mark 210 and the outer peripheral welding mark 220 may not be formed. Further, in the above embodiment, the welding recess 230 may not be formed in the cover plate 200.

  Further, in the above embodiment, the shape of the cover plate 200 or the like described using the first to fourth virtual lines VL1 to VL4 and the first to fourth points P1 to P4 is not essential and can be variously modified. is there.

  Further, in the first embodiment, when viewed in the Z direction, the side parallel to the second direction (for example, the Y direction) and the third direction (for example, the X direction) of the outer peripheral line OL of the cover plate 200 are parallel. Both sides are portions located inside the outer peripheral line of the end plate 106 (side portions Sy2 and Sx2), and two portions (side portions Sy2 and Sx2) that are sandwiching the side portion and coincide with the outer peripheral line position of the end plate 106 (side portion). Sy1 and Sx1) are included, but only one of the side parallel to the second direction and the side parallel to the third direction may have such a configuration. Even in such a case, the cover plate 200 can be positioned in the direction orthogonal to the direction.

  Further, in the above embodiment, the number of power generation units 102 (single cells 110) included in the fuel cell stack 100 is merely an example, and the number of power generation units 102 (single cells 110) is required for the fuel cell stack 100. It is appropriately determined according to the output voltage and the like. In addition, in the above-described embodiment, a layer having no power generation function and electrical conductivity between one power generation unit 102 and another power generation unit 102 (for example, a layer for ensuring a gas flow path in the surface direction). May intervene. Even in this case, the structure in the range from the uppermost power generation unit 102 to the lowermost power generation unit 102 (that is, the layer that does not have the power generation function and has conductivity) is the power generation block 103. .

  Further, the material forming each member in the above embodiment is merely an example, and each member may be formed of other materials. For example, the cover plate 200 and the end plate 106 may be made of the same material.

  In the present specification, the fact that the member B and the member C face each other with the member (or a portion having the member, the same applies hereinafter) sandwiched therebetween is not limited to the form in which the member A and the member B or the member C are adjacent to each other It includes a form in which another component is interposed between the member A and the member B or the member C. For example, another layer may be provided between the electrolyte layer 112 and the air electrode 114. Even with such a configuration, it can be said that the air electrode 114 and the fuel electrode 116 face each other with the electrolyte layer 112 in between.

  Further, in the above-described embodiment, the SOFC that generates electric power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas is targeted, but the present invention is directed to the electrolysis reaction of water. It is similarly applicable to an electrolysis single cell which is a constituent unit of a solid oxide electrolysis cell (SOEC) that produces hydrogen by utilizing hydrogen, or an electrolysis cell stack including a plurality of electrolysis single cells. The configuration of the electrolysis cell stack is publicly known as described in, for example, Japanese Patent Application Laid-Open No. 2014-207120, and therefore will not be described in detail here. It is a composition. That is, the fuel cell stack 100 in the above embodiment may be read as an electrolysis cell stack, the power generation unit 102 as an electrolysis cell unit, and the unit cell 110 as an electrolysis unit cell. However, during the operation of the electrolysis cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the flow passage communication hole 109 is used. Water vapor as a raw material gas is supplied via. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolysis cell stack through the passage communication hole 109. Even in the electrolytic cell stack having such a configuration, if the configuration is the same as that of the above-described embodiment, the same operation and effect as those of the above-described embodiment are achieved.

 Further, although the solid oxide fuel cell (SOFC) has been described as an example in the above embodiment, the present invention can be applied to other types of fuel cells (or electrolytic single cells) such as a molten carbonate fuel cell (MCFC). Is also applicable.

10: Heat insulation container 20: Support 22: Bolt 24: Nut 26: Insulation sheet 40: Auxiliary device 60: Piping 70: Piping 100: Fuel cell stack 102: Fuel cell power generation unit 103: Power generation block 104: End plate 105: Flow path Through hole 106: End plate 107: Flow channel recess 108: Fastening communication hole 109: Flow channel communication hole 110: Fuel cell single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 120: Separator 121: Hole 130: Air electrode side frame 131: Hole 132: Oxidizing gas supply communication hole 133: Oxidizing gas discharge communication hole 134: Air electrode side current collector 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply communication hole 143 : Fuel gas exhaust communication hole 144: Fuel electrode side current collector 150: Interconnect 161: Oxidizing gas introduction manifold 162: Oxidizing gas discharge manifold 163: Oxidizing gas introduction communication flow path 164: Oxidizing gas discharge communication flow path 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 173: Fuel gas introduction communication flow path 174: Fuel gas discharge communication flow path 176: Fuel chamber 200: Cover plate 202: Gas hole 204: Bolt 210: Flow path welding mark 220: Perimeter welding mark 230: Welding recess

Claims (18)

An electrochemical reaction block in which a plurality of electrochemical reaction single cells each including an electrolyte layer and an air electrode and a fuel electrode facing each other in the first direction with the electrolyte layer interposed therebetween are arranged side by side in the first direction,
A plurality of flat plate-shaped members arranged side by side in the first direction at a position on one side in the first direction with respect to the electrochemical reaction block;
And an electrochemical reaction cell stack in which a shared gas channel extending over the electrochemical reaction block is formed,
The outer surface that is the one side surface of the outer flat plate member that is the flat plate member that is located at the end on the one side in the first direction of the plurality of flat plate members has the first Gas holes are formed in a position that does not overlap with the shared gas flow path when viewed in a direction,
Inside the structure constituted by the plurality of flat plate-shaped members, a communication gas flow path that connects the gas hole and the shared gas flow path is formed ,
A first concave portion forming the communication gas flow path on the one side in the first direction of the structure constituted by the flat plate-shaped member excluding the outer flat plate-shaped member among the plurality of flat plate-shaped members. Is formed,
The gas hole of the outer flat plate-shaped member is arranged at a position overlapping with the first recess in the first direction,
An electrochemical reaction cell stack , wherein a portion of the first recess that does not overlap with the gas hole is closed by the outer flat plate member . The electrochemical reaction cell stack according to claim 1 , wherein
A first welding mark is formed on the outer surface of the outer flat plate member along a first imaginary line surrounding the communication gas flow path in the first direction. Electrochemical reaction cell stack. The electrochemical reaction cell stack according to claim 2 ,
A second recess is formed on the outer surface of the outer plate member,
An electrochemical reaction cell stack, wherein at least a part of the first welding mark is formed in the second recess. The electrochemical reaction cell stack according to claim 3 ,
An electrochemical reaction cell stack, wherein at least a part of the first welding mark formed in the second recess is separated from a side surface of the second recess. The electrochemical reaction cell stack according to claim 3 ,
At least a part of the first welding mark formed in the second recess is in contact with a side surface of the second recess, and the electrochemical reaction cell stack is characterized. In the electrochemical reaction cell stack according to any one of claims 2 to 5 ,
When viewed from the first direction, the shape of the outer flat plate-shaped member is
One of a second virtual line which is a peripheral line of a minimum virtual rectangular area including the outer flat plate-shaped member and a third virtual line which is a virtual straight line orthogonal to a part of the first virtual line. The intersection is the first point,
The point closest to the first point among the intersections of the third virtual line and the outer peripheral line of the outer flat plate-shaped member is the second point,
When the point closest to the first point among the intersections of the third virtual line and the first virtual line is the third point,
An electrochemical reaction cell stack having a shape in which the second point satisfying a specific condition including a condition defined by the following formula (1) is present.
L ₂₃ <L ₁₃ (1)
(However, L ₁₃ is the distance between the first point and the third point, and L ₂₃ is the distance between the second point and the third point.) The electrochemical reaction cell stack according to claim 6 ,
The electrochemical reaction cell stack, wherein the specific condition includes a condition defined by the following formula (2).
L ₂₃ ≦ L ₁₃ × 3/4 (2) The electrochemical reaction cell stack according to claim 6 or 7 , wherein
When viewed from the first direction, the shape of the outer flat plate-shaped member satisfies the specific condition whenever the second point is within a range of a predetermined length on the outer peripheral line of the outer flat plate-shaped member. An electrochemical reaction cell stack, which is characterized in that The electrochemical reaction cell stack according to claim 8 ,
The electrochemical reaction cell stack, wherein the predetermined length is 1/4 or more of a length of the virtual rectangular region in a direction parallel to the outer peripheral line within the range. The electrochemical reaction cell stack according to any one of claims 6 to 9 ,
When viewed from the first direction, the outer flat plate member has a shape in which a third recess is present in the outer peripheral line of the outer flat plate member, and the second point is in the third recess. An electrochemical reaction cell stack, which is characterized in that the specific conditions are sometimes satisfied. The electrochemical reaction cell stack according to claim 10 , further comprising:
An electrochemical reaction cell stack comprising a bolt screwed to at least one of two convex portions sandwiching the third concave portion in the outer flat plate-shaped member in the first direction. The electrochemical reaction cell stack according to any one of claims 6 to 11 ,
On the outer surface of the outer plate member, a second welding mark is formed between the second point and the third point satisfying the specific condition, and an electrochemical characteristic is provided. Reaction cell stack. The electrochemical reaction cell stack according to any one of claims 6 to 12 ,
In the first direction, the first welding mark has the following expression (3) when the other intersection point of the second virtual line and the third virtual line is a fourth point. An electrochemical reaction cell stack, characterized in that it is formed so as to satisfy the conditions defined by.
L ₁₃ ≧ L ₁₄ × 1/8 (3)
(However, L ₁₄ is the distance between the first point and the fourth point.) The electrochemical reaction cell stack according to any one of claims 6 to 13 ,
The outer flat plate-shaped member and an adjacent flat plate-shaped member that is the flat plate-shaped member that is adjacent to the outer flat plate-shaped member among the plurality of flat plate-shaped members have different thermal expansion coefficients from each other. Chemical reaction cell stack. The electrochemical reaction cell stack according to any one of claims 6 to 14 ,
In the first direction, at least a part of a side of the outer flat plate-shaped member that is parallel to a second direction that is orthogonal to the first direction, and is orthogonal to the first direction, and An adjacent flat plate shape in which the position of at least a part of a side parallel to the third direction that is not parallel to the second direction is the flat plate member adjacent to the outer flat plate member of the plurality of flat plate members. An electrochemical reaction cell stack characterized by being coincident with a position of a fourth virtual line which is a peripheral line of a minimum virtual rectangular area including a member. The electrochemical reaction cell stack according to claim 15 , wherein
In the first direction, at least one of the side parallel to the second direction and the side parallel to the third direction of the outer peripheral line of the outer flat plate-shaped member is the adjacent flat plate. A portion located inside the outer peripheral line of the plate-shaped member and two portions sandwiching the portion located inside the outermost line and matching the position of the outer peripheral line of the adjacent flat plate-shaped member are included. Electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 2 to 5 ,
The outer flat plate-shaped member includes a first outer flat plate-shaped member and a second outer flat plate-shaped member that are arranged apart from each other,
Inside the structure constituted by the plurality of flat plate-shaped members, the first communication gas that connects the gas holes formed in the first outer flat plate-shaped member and one of the common gas flow paths. A flow path, and a second communication gas flow path that connects the gas hole formed in the second outer flat plate member and the other common gas flow path,
An electrochemical reaction cell stack, wherein the first welding mark is formed on each of the outer surfaces of the first outer flat plate member and the second outer flat plate member. The electrochemical reaction cell stack according to claim 17 , wherein
One of the first communication gas channel and the second communication gas channel is the flat plate shape adjacent to the outer flat plate member of the plurality of flat plate members in the first direction. When the adjacent flat plate-shaped member, which is a member, is divided into three regions in a predetermined direction, they are arranged so as to overlap with one end region,
The other of the first communication gas flow path and the second communication gas flow path is the other when the adjacent flat plate-shaped member is divided into three regions in the predetermined direction in the first direction view. An electrochemical reaction cell stack, wherein the electrochemical reaction cell stack is arranged so as to overlap with an area at an end of the cell.

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