Fuel cell stack

Abstract

To ensure that even if the end face of the air vent tube abuts against the wall of the end unit, the discharge of air bubbles by the tube is not obstructed, and air bubbles can be discharged. [Solution] The dry-side end unit 18 of the fuel cell stack 10 has an end receiving portion 98 that receives the rear end 80B of the pipe 80 provided in the cooling medium discharge channel PA6. The end receiving portion 98 has a first recessed portion 100 which is recessed in a direction opposite to the side of the cell stack 12 and opens toward the side of the cell stack 12, and has a first wall surface 100B to which the end face 83 of the pipe 80 can abut, and a second recessed portion 102 which is recessed from a part of the first wall surface 100B in the same direction as the first recessed portion 100 and opens toward the first wall surface 100B, and communicates with the internal passage 82 of the pipe 80.

Description

Technical Field

[0001] The present invention relates to a fuel cell stack.

Background Art

[0002] In recent years, in order to enable more people to access affordable, reliable, sustainable, and advanced energy, research and development have been conducted on fuel cells that contribute to energy efficiency.

[0003] A fuel cell stack has a cell stack formed by laminating a plurality of power generation cells. In the fuel cell stack, a cooling medium flow path through which a liquid cooling medium (refrigerant) containing water or the like flows in the stacking direction of the cell stack is provided for cooling the cell stack. In such a fuel cell stack, in order to capture bubbles generated in a cooling medium discharge flow path that discharges the cooling medium supplied to the fuel cell stack from the fuel cell stack and discharge them to the outside, a fuel cell stack in which a tubular body, a so-called air vent pipe, is disposed in the cooling medium discharge flow path is known (for example, Patent Document 1).

[0004] The air vent pipe extends in the stacking direction of the power generation cells in the cell stack through the cooling medium discharge flow path, and both ends are supported by end units disposed at the ends of the fuel cell stack. The support structure of the air vent pipe by the end units preferably allows for manufacturing assembly, such as stacking errors of each power generation cell in the cell stack. Therefore, the air vent pipe is supported by the end units so as to be displaceable in the radial direction and the longitudinal direction (the stacking direction of the cell stack) within a range necessary for allowing stacking errors and the like.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In the fuel cell stack described above, the vent pipe is supported so as to be displaceable in the longitudinal direction relative to the end unit, which may cause the end face of the vent pipe to abut against the wall of the end unit. When the end face of the vent pipe abuts against the wall of the end unit, the opening at the end of the vent pipe may be blocked by the wall of the end unit, which may hinder the discharge of air bubbles by the vent pipe. [Problems that the invention aims to solve]

[0007] In view of the above background, the present invention aims to enable the discharge of air bubbles by the air vent pipe even when the end face of the pipe constituting the air vent pipe abuts against the wall of the end unit, thereby preventing obstruction of bubble discharge. This will ultimately contribute to energy efficiency. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the present invention provides a fuel cell stack comprising: a cell stack formed by stacking a plurality of power generation cells in a predetermined direction; a first end unit and a second end unit respectively arranged at both ends of the cell stack in the stacking direction; a cooling medium flow path that penetrates the cell stack in the stacking direction and includes a cooling medium discharge flow path for discharging the cooling medium supplied to the cell stack to the outside; and a tubular body arranged in the cooling medium discharge flow path extending in the stacking direction, with its ends supported by the first end unit and the second end unit, and including an internal passage with open ends, wherein the second end unit has an end receiving portion for receiving the end of the tubular body on the second end unit side, the end receiving portion has a first recessed portion that is recessed in a direction opposite to the cell stack and opens toward the cell stack, and has a first wall surface to which the end face of the tubular body can abut; and a second recessed portion provided in a part of the first recessed portion, recessed from the first wall surface in the same direction as the first recessed portion and opening toward the first wall surface, and communicating with the internal passage. [Effects of the Invention]

[0009] According to the present invention, even if the end face of the tube abuts against the wall of the end unit, the discharge of air bubbles by the tube is not hindered, and air bubbles can be discharged. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic perspective view showing the overall configuration of the fuel cell stack according to this embodiment. [Figure 2] Longitudinal cross-sectional view of the fuel cell stack according to this embodiment [Figure 3] Enlarged vertical cross-sectional view of the main part (dry side end unit portion) of the fuel cell stack according to this embodiment. [Figure 4] Enlarged cross-sectional view along line IV-IV in Figure 3 [Figure 5] Enlarged cross-sectional view along line VV in Figure 3 (with pipe body) [Figure 6] Enlarged cross-sectional view along line VV in Figure 3 (without pipe body) [Figure 7] A cross-sectional view equivalent to the enlarged cross-sectional view along line VV in Figure 3, showing the displacement of the pipe relative to the dry-side end unit. [Modes for carrying out the invention]

[0011] An embodiment of the fuel cell stack 10 will be described below with reference to the drawings. In the following description, the three orthogonal axes of the front-rear direction, left-right direction, and up-down direction will be defined as shown in the figures.

[0012] First, the overall structure of the fuel cell stack 10 will be described with reference to Figure 1. The fuel cell stack 10 has a cell stack 14 formed by stacking a plurality of power generation cells 12 in the front-to-back direction (a predetermined direction), a wet-side end unit 16 (first end unit) located at one end of the cell stack 14 in the stacking direction, and a dry-side end unit 18 (second end unit) located at the other end of the cell stack 14 in the stacking direction. The cell stack 14, the wet-side end unit 16, and the dry-side end unit 18 are fastened to each other in the stacking direction by fastening members (not shown) and housed in a stack case (not shown).

[0013] The fuel cell stack 10 is supplied with hydrogen gas (fuel gas) and oxidizer gas (air) as reaction gases.

[0014] In the following explanation, the stacking direction of the cell stack 14 may be referred to as the front-to-back direction.

[0015] Each cell stack 14 includes a rectangular plate-shaped electrolyte membrane / electrode structure 20, a first separator 24 positioned on one side of the electrolyte membrane / electrode structure 20, and a second separator 26 positioned on the other side of the electrolyte membrane / electrode structure 20. On the left edge of each power generation cell 12, a hydrogen gas supply opening 30, a refrigerant discharge opening 32, and an oxidizer gas discharge opening 34 are formed, from top to bottom, penetrating in the stacking direction. On the right edge of each power generation cell 12, an oxidizer gas supply opening 36, a refrigerant supply opening 38, and a hydrogen gas discharge opening 40 are formed, from top to bottom, penetrating in the stacking direction.

[0016] The wet-side end unit 16 has a terminal plate 42, an electrical insulation plate 44, and an end plate 46, which are stacked in order from the power generation cell 12 side. On the left edge of the wet-side end unit 16, a hydrogen gas supply opening 48, a refrigerant discharge opening 50, and an oxidizer gas discharge opening 52 are formed through the unit in the front-to-back direction, from top to bottom. On the right edge of the wet-side end unit 16, an oxidizer gas supply opening 54, a refrigerant supply opening 56, and a hydrogen gas discharge opening 58 are formed through the unit in the front-to-back direction, from top to bottom. Each opening provided in the wet-side end unit 16 is arranged in the same way as each opening provided in the power generation cell 12 and communicates with the corresponding hydrogen gas supply opening 30, hydrogen gas discharge opening 40, oxidizer gas supply opening 36, oxidizer gas discharge opening 34, refrigerant supply opening 38, and refrigerant discharge opening 32 of the power generation cell 12.

[0017] The hydrogen gas supply opening 48 communicates with the hydrogen gas supply opening 30 of the cell stack 14. The refrigerant discharge opening 50 communicates with the refrigerant discharge opening 32 of the power generation cell 12. The oxidant gas discharge opening 52 communicates with the oxidant gas discharge opening 34 of the power generation cell 12. The oxidant gas supply opening 54 communicates with the oxidant gas supply opening 36 of the power generation cell 12. The refrigerant supply opening 56 communicates with the refrigerant supply opening 38 of the cell stack 14. The hydrogen gas discharge opening 58 communicates with the hydrogen gas discharge opening 40 of the power generation cell 12.

[0018] The dry-side end unit 18 has a terminal plate 60, an electrical insulation plate 62, and an end plate 64, which are laminated in order from the side of the power generation cell 12. The terminal plate 60 and the electrical insulation plate 62 are formed with a hydrogen gas supply opening 61, a hydrogen gas discharge opening 67, an oxidant gas supply opening 63, an oxidant gas discharge opening (not shown), a refrigerant supply opening 65, and a refrigerant discharge opening (not shown) penetrating therethrough in the front-rear direction by the same arrangement as that of the wet-side end unit 16. Note that these openings are not formed in the end plate 64. Each opening provided in the dry-side end unit 18 has the same arrangement as each opening provided in the power generation cell 12 and communicates with the corresponding hydrogen gas supply opening 30, hydrogen gas discharge opening 40, oxidant gas supply opening 36, oxidant gas discharge opening 34, refrigerant supply opening 38, and refrigerant discharge opening 32 of the power generation cell 12.

[0019] Thereby, hydrogen gas flows in the stacking direction of the cell stack 14 through the gas supply flow path PA1 and is supplied to each power generation cell 12. The hydrogen off-gas (exhaust gas) generated in each power generation cell 12 flows from each power generation cell 12 in the stacking direction of the cell stack 14 through the exhaust gas flow path PA2.

[0020] The oxidant gas may be air and flows in the stacking direction of the cell stack 14 through the gas supply flow path PA3 and is supplied to each power generation cell 12. The oxidant off-gas (exhaust gas) generated in each power generation cell 12 flows from each power generation cell 12 in the stacking direction of the cell stack 14 through the exhaust gas flow path PA4.

[0021] The refrigerant (cooling medium) may be a liquid containing water or the like, and flows in the stacking direction of the cell stack 14 through the refrigerant supply channel PA5 and is supplied to each power generation cell 12 to cool each power generation cell 12. The refrigerant discharged from each power generation cell 12 flows in the stacking direction of the cell stack 14 through the refrigerant discharge channel PA6 (cooling medium discharge channel).

[0022] The fuel cell stack 10 generates electrons and water through an electrochemical reaction between hydrogen gas and oxidizer gas supplied to each power generation cell 12, and electricity is extracted from terminal plates 42 and 60. The generated water produced in the fuel cell stack 10 is discharged outside the fuel cell stack 10 through exhaust gas channels PA2 and PA4.

[0023] Next, the details of the refrigerant discharge channel PA6 of the fuel cell stack 10 and the structures related to the refrigerant discharge channel PA6 will be described with reference to Figures 2 to 7. In Figures 2 to 7, elements corresponding to Figure 1 are given the same reference numerals as those used in Figure 1, and their explanations are omitted.

[0024] As shown in Figure 2, the end plate 46 of the wet-side end unit 16 has a port placement plate 45 and a port member 47 attached to the port placement plate 45. An airtight sealing member 66 is provided between the port member 47 and the electrical insulation plate 44. An airtight sealing member 68 is provided between the electrical insulation plate 44 and the terminal plate 42.

[0025] The terminal plate 42, electrical insulation plate 44, and port member 47 of the wet-side end unit 16 are each formed with through holes 72, 74, and 76 that constitute the refrigerant discharge opening 50.

[0026] An airtight sealing member 69 is provided between the terminal plate 60 and the electrical insulation plate 62 of the dry-side end unit 18. A gasket 71 is provided between the electrical insulation plate 62 and the end plate 64. The terminal plate 60 of the dry-side end unit 18 has a through hole 73 which constitutes the refrigerant discharge opening of the dry-side end unit 18. The electrical insulation plate 62 has a non-through hole 75 which constitutes the refrigerant discharge opening of the dry-side end unit 18.

[0027] A pipe 80 is positioned in the refrigerant discharge channel PA6. The pipe 80 is an air vent pipe that captures air bubbles in the refrigerant flowing through the refrigerant discharge channel PA6 and discharges them to the outside. The pipe 80 extends approximately horizontally in the stacking direction of the cell stack 14, i.e., in the front-to-back direction, over the upper part of the refrigerant discharge channel PA6. The pipe 80 has a cylindrical shape and includes an internal passage 82 with openings at both ends.

[0028] Support holes 84 are formed through the terminal plate 42 of the wet-side end unit 16 in the stacking direction of the cell laminate 14. Support holes 86 are formed through the terminal plate 60 of the dry-side end unit 18 in the stacking direction of the cell laminate 14. The pipe body 80 is supported by the wet-side end unit 16 by its front end passing through the support holes 84 of the terminal plate 42. The pipe body 80 is supported by the dry-side end unit 18 by its rear end passing through the support holes 86 of the terminal plate 60.

[0029] A through-hole 88 is formed in the cell stack 14 that constitutes the upper part of the refrigerant discharge opening 32, penetrating in the stacking direction of the cell stack 14. The pipe 80 is inserted into the through-hole 88 between the wet-side end unit 16 and the dry-side end unit 18.

[0030] The support holes 84, 86 and the through hole 88 are arranged on the same axis and have an inner diameter larger than the outer diameter R1 (see Figure 5) of the pipe body 80. In other words, the inner diameters of the support holes 84, 86 and the through hole 88 are larger than the outer shape of the pipe body 80 determined by the outer diameter R1. As a result, the pipe body 80 is loosely fitted into the support holes 84, 86 and the through hole 88 and is displaceable in the axial and radial directions relative to the wet end unit 16 and the dry end unit 18.

[0031] A tapered hole 90 is formed through the electrical insulation plate 44 of the wet-side end unit 16 in the stacking direction of the cell laminate 14, serving as a front end receiving portion for receiving the front end 80A of the pipe body 80. The tapered hole 90 tapers toward the end plate 46. A port member 94 having a refrigerant discharge hole 92 communicating with the tapered hole 90 is attached to the port arrangement plate 45. An airtight sealing member 96 is provided between the port arrangement plate 45 and the port member 94.

[0032] A rear end receiving portion 98 is formed on the electrical insulation plate 44 of the dry-side end unit 18. Details of the rear end receiving portion 98 will be explained with reference to Figures 3 to 7.

[0033] The rear end receiving portion 98 includes a first recessed portion 100 and a second recessed portion 102.

[0034] The first recessed portion 100 is recessed in a direction opposite to the side of the cell stack 14 (towards the rear) and opens toward the side of the cell stack 14 (towards the front). The first recessed portion 100 has a tapered inner circumferential wall surface 100A that expands toward the side of the cell stack 14, and a flat first wall surface 100B that extends radially inward from the minimum inner diameter end (bottom) of the inner circumferential wall surface 100A in a direction perpendicular to the stacking direction of the cell stack 14.

[0035] The first recess 100 has a circular cross-sectional shape on substantially the same axis as the support hole 86 and has a minimum inner diameter larger than the outer diameter R1 of the pipe body 80. As a result, the first recess 100 receives the rear end 80B of the pipe body 80 in a loosely fitted state that allows movement in the stacking direction (axial direction) of the cell stack 14 and in a direction perpendicular to the stacking direction of the cell stack 14 (radial direction). In other words, the rear end 80B of the pipe body 80 can enter the first recess 100.

[0036] The second recessed portion 102 is recessed in the same direction as the first recessed portion 100 from approximately the upper half of the bottom of the first recessed portion 100, and includes a portion that opens to approximately the upper half of the first wall surface 100B with an area smaller than the tip area of ​​the rear end of the pipe body 80, and communicates with the internal passage 82 of the pipe body 80. The second recessed portion 102 has a tapered inner circumferential wall surface 102A that expands toward the side of the cell stack 14, and a flat second wall surface 102B that extends radially inward from the smallest inner diameter end (bottom) of the inner circumferential wall surface 102A in a direction perpendicular to the stacking direction of the cell stack 14.

[0037] The first wall surface 100B of the first recess 100 has a semicircular-crescent shape in its planar form, which combines the approximately semicircular shape and approximately crescent shape remaining in approximately the lower half of the first recess 100 through the opening of the second recess 102, and the annular rear end surface 83 of the pipe body 80 can come into contact with it. The first wall surface 100B refers to the semicircular-crescent shape of the wall surface shown in the figure.

[0038] The vertical dimension H1 (Figure 6) of the first wall surface 100B of the first recess 100 is less than the inner diameter R2 (vertical dimension, Figure 5) of the internal passage 82. In other words, H1 <R2である。

[0039] The maximum vertical dimension H2 (Figure 6) of the second recess 102 is less than the outer diameter R1 (vertical dimension, Figure 5) of the pipe body 80. In other words, H2 <R1である。

[0040] Because the pipe body 80, the first wall surface 100B of the first recess 100, and the second recess 102 have this arrangement and dimensional relationship, even if the pipe body 80 comes into contact with the first wall surface 100B, the pipe body 80 cannot enter the second recess 102. Furthermore, even if the pipe body 80 is displaced vertically relative to the dry-side end unit 18, the state in which the second recess 102 communicates with the internal passage 82 of the pipe body 80 is maintained while the pipe body 80 is in contact with the first wall surface 100B.

[0041] Because the planar shape of the first wall surface 100B is a semicircular-crescent shape, which is a combination of a roughly semicircular shape and a roughly crescent shape, compared to the case where it is circular or the like, the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18, and the inflow of air bubbles into the pipe body 80 is not obstructed by the first wall surface 100B, both of which can be achieved without requiring a large vertical direction.

[0042] The second recess 102 includes a lateral extension 104 that extends to the right of the portion corresponding to the right outer edge of the first recess 100. The lateral extension 104 communicates directly with the upper edge of the non-through hole 75 below. As a result, the second recess 102 communicates with the non-through hole 75 of the electrical insulation plate 44, which forms part of the refrigerant discharge channel PA6, with a relatively large opening, allowing bubbles to move smoothly from the refrigerant discharge channel PA6 to the second recess 102 without encountering significant flow resistance.

[0043] According to the above configuration, as shown in Figures 1 to 3, bubbles contained in the refrigerant that flows from the refrigerant supply channel PA5 to the refrigerant discharge channel PA6 after cooling the cell stack 14 are captured in the internal passage 82 of the pipe 80 from the space between the first recess 100 and the second recess 102 at the rear end receiving portion 98 of the dry side end unit 18 and flow into the internal passage 82. Due to the pressure of the refrigerant discharge channel PA6, these bubbles flow through the internal passage 82 towards the wet side end unit 16, and further flow through the tapered hole 90 of the wet side end unit 16 and are discharged to the outside from the refrigerant discharge hole 92.

[0044] The rearward displacement of the pipe body 80 relative to the cell stack 14 is restricted by the rear end surface 83 of the pipe body 80 abutting against the first wall surface 100B of the first recess 100. Even when the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the first recess 100, the second recess 102 ensures that air bubbles flow into the internal passage 82 of the pipe body 80, and the discharge of air bubbles by the pipe body 80 is maintained.

[0045] In other words, it is possible to ensure that the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18, and that the inflow of air bubbles into the pipe body 80 is not obstructed by the first wall surface 100B.

[0046] Air bubbles have a lower specific gravity than liquid refrigerant and accumulate on the upper side of the refrigerant discharge channel PA6. Since the rear end receiving section 98 of the dry-side end unit 18 is located above the refrigerant discharge channel PA6, the air bubbles that have accumulated on the upper side of the refrigerant discharge channel PA6 flow from the rear end receiving section 98 to the pipe 80. This allows for efficient capture and discharge of air bubbles in the refrigerant by the pipe 80 located above the refrigerant discharge channel PA6.

[0047] In other words, since the rear end receiving section 98, including the first recess 100 and the second recess 102, is located above the refrigerant discharge channel PA6, air bubbles in the refrigerant are effectively captured in the rear end receiving section 98. Furthermore, because the second recess 102 is located above the first recess 100, air bubbles are also effectively captured in the second recess 102.

[0048] If the pipe body 80 is displaced upward, or if the rear end of the pipe body 80 is tilted in a direction that displaces upward relative to the cell stack 14, the pipe body 80 may come into contact with the inner circumferential wall surface 100A of the first recess 100, as shown by the solid line in Figure 7. Even in this case, the rear end surface 83 of the pipe body 80 comes into contact with the first wall surface 100B of the first recess 100, preventing the pipe body 80 from falling into the second recess 102. Moreover, the internal passage 82 is not blocked by the first wall surface 100B.

[0049] As a result, even if the rear end surface 83 of the pipe body 80 is displaced upward as shown by the solid line in Figure 7, communication between the internal passage 82 of the pipe body 80 and the non-penetrating hole 75 (refrigerant discharge channel PA6) is maintained by the second recess 102, and air bubbles in the refrigerant are captured and discharged by the pipe body 80.

[0050] Furthermore, if the pipe body 80 is displaced downward, or if the rear end of the pipe body 80 is tilted downward relative to the cell stack 14, the pipe body 80 may come into contact with the inner circumferential wall surface 100A of the first recess 100, as shown by the dashed line in Figure 7. Even in this case, the rear end surface 83 comes into contact with the first wall surface 100B of the first recess 100, preventing the pipe body 80 from falling into the second recess 102, and also preventing the internal passage 82 from being blocked by the first wall surface 100B.

[0051] As a result, even if the rear end surface 83 of the pipe body 80 is displaced downward as shown by the dashed line in Figure 7, communication between the internal passage 82 of the pipe body 80 and the non-penetrating hole 75 (refrigerant discharge channel PA6) is maintained by the second recess 102, and air bubbles in the refrigerant are captured and discharged by the pipe body 80.

[0052] In other words, whether the rear end surface 83 of the pipe body 80 is displaced upward or downward, it is possible to reliably ensure that the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18, and that the inflow of air bubbles into the pipe body 80 is not obstructed by the first wall surface 100B.

[0053] The embodiments are not limited to the above configuration and can be broadly modified. The planar shape of the first wall surface 100B of the first recess 100 is not limited to the semicircular / crescent-like shape shown, but may be a semicircular, crescent-shaped, or other shape including the center of the first recess 100.

[0054] The inner circumferential wall surface 100A of the first recess 100 and the inner circumferential wall surface 102A of the second recess 102 may be straight surfaces.

[0055] In conclusion, the above embodiments can be summarized as follows:

[0056] One embodiment of the fuel cell stack 10 comprises a cell stack 14 formed by stacking a plurality of power generation cells 12 in a predetermined direction, a wet-side end unit 16 (first end unit) and a dry-side end unit 18 (second end unit) respectively arranged at both ends of the cell stack 14 in the stacking direction, a cooling medium flow path including a refrigerant discharge flow path PA6 that penetrates the cell stack 14 in the stacking direction and discharges the cooling medium supplied to the cell stack 14 to the outside, and a pipe body 80 arranged in the refrigerant discharge flow path PA6 that extends in the stacking direction, with its front end 80A (end) and rear end 80B (end) supported by the wet-side end unit 16 and the dry-side end unit 18, and including an internal passage 82 with open ends, wherein the dry side The end unit 18 has a rear end receiving portion 98 (end receiving portion) that receives the end of the pipe body 80 on the dry side end unit 18 side, and the rear end receiving portion 98 has a first recessed portion 100 which is recessed in a direction opposite to the side of the cell stack 14 and opens toward the side of the cell stack 14, and receives the rear end 80B (end) of the pipe body 80 so as to be displaceable in the stacking direction of the cell stack 14 and in a direction perpendicular to the stacking direction, and has a first wall surface 100B to which the rear end face 83 (end face) of the pipe body 80 can abut, and a second recessed portion 102 which is recessed in the same direction as the first recessed portion 100 from a part of the first wall surface 100B, opens toward the first wall surface 100B with an area smaller than the tip area of ​​the end of the pipe body 80, and communicates with the internal passage 82 of the pipe body 80.

[0057] According to this embodiment, even if the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18, the inflow of air bubbles into the pipe body 80 is not obstructed, and the discharge of air bubbles by the pipe body 80 can be maintained.

[0058] In the above embodiment, preferably, the vertical dimension H1 of the first wall surface 100B is less than the inner diameter R2 (vertical dimension) of the internal passage 82, and the vertical dimension H2 of the second recess 102 is less than the outer diameter R1 (vertical dimension) of the pipe body 80.

[0059] According to this embodiment, even if the pipe body 80 is displaced vertically relative to the dry-side end unit 18, it is possible to reliably achieve both that the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18 and that the inflow of air bubbles into the pipe body 80 is not obstructed by the first wall surface 100B.

[0060] In the above embodiment, preferably, the second recess 102 is provided above the first recess 100.

[0061] According to this embodiment, air bubbles in the second recess 102 are effectively captured.

[0062] In the above embodiment, preferably, the pipe body 80 has a cylindrical shape, and the first wall surface 100B has a planar shape that is approximately semicircular or approximately crescent-shaped in the approximately lower half of the first recess 100.

[0063] In this embodiment, the rear end surface 83 of the pipe body 80 abuts against the first wall surface 100B of the dry-side end unit 18, and the inflow of air bubbles into the pipe body 80 is not obstructed by the first wall surface 100B, both without requiring a large vertical range.

[0064] In the above embodiment, preferably, the second recess 102 extends outward from a corresponding position on the outer edge of the first recess 100 and includes a side extension 104 that communicates directly with the refrigerant discharge channel PA6.

[0065] According to this embodiment, the movement of bubbles from the refrigerant discharge channel PA6 to the second recess 102 is carried out smoothly without encountering significant flow resistance.

[0066] In the above embodiment, preferably, the rear end receiving portion 98 is located at the upper part of the refrigerant discharge channel PA6.

[0067] According to this embodiment, bubbles in the cooling medium are effectively captured in the rear end receiving section 98.

[0068] In the above embodiment, preferably, the dry-side end unit 18 has, in order from the side of the cell laminate 14, a terminal plate 60, an electrical insulation plate 62, and an end plate 64, the electrical insulation plate 62 having the rear end receiving portion 98 (end receiving portion), and the terminal plate 60 having an opening 73A that opens the support hole 86 through which the pipe body 80 passes and the second recess 102 toward the refrigerant discharge flow path PA6.

[0069] In this embodiment, bubbles flow smoothly from the refrigerant discharge channel PA6 to the second recess 102.

[0070] In the above embodiment, preferably, the support hole 86 is larger than the outer diameter R1 (outer dimensions) of the pipe body 80.

[0071] According to this embodiment, the support of the pipe body 80 in the terminal plate 60 is provided so that it can be displaced in the stacking direction and radial direction of the cell stack 14. [Explanation of symbols]

[0072] 10: Fuel cell stack 12: Power generation cell 14: Cell laminate 16: Wet side end unit (first end unit) 18: Dry side end unit (second end unit) 42: Terminal Plate 44: Electrical insulation plate 46: End plate 60: Terminal Plate 62: Electrical insulation plate 64: End plate 73A: Opening 80: Body 82: Internal passage 84: Support hole 86: Support hole 100: First depression 100B: First wall 102: Second depression 104: Side extension PA6: Refrigerant discharge channel (cooling medium discharge channel) H1: Vertical dimension H2: Vertical dimension R1: Outer diameter R2: Inner diameter

Claims

1. A cell stack formed by stacking multiple power generation cells in a predetermined direction, A first end unit and a second end unit are respectively arranged at both ends in the stacking direction of the cell stack, A cooling medium channel that penetrates the stacking direction of the cell stack and includes a cooling medium discharge channel for discharging the cooling medium supplied to the cell stack to the outside, A fuel cell stack having a cooling medium discharge channel comprising a tubular body extending in the stacking direction of the cell stack, supported at its ends by the first end unit and the second end unit, and including an internal passage with open ends, The second end unit has an end receiving portion for the pipe body, The end receiving portion is, A first recessed portion is recessed in a direction opposite to the side of the cell stack and opens toward the side of the cell stack, receiving the end of the tube so as to be displaceable in the stacking direction of the cell stack and in a direction perpendicular to the stacking direction, and having a first wall surface to which the end face of the tube can abut, A fuel cell stack having a second recess that extends in the same direction as the first recess from a part of the first wall surface, opens to the first wall surface with an area smaller than the tip area of ​​the end of the pipe, and communicates with the internal passage of the pipe.

2. The fuel cell stack according to claim 1, wherein the vertical dimension of the first wall surface is smaller than the vertical dimension of the internal passage, and the vertical dimension of the second recess is smaller than the vertical dimension of the pipe.

3. The fuel cell stack according to claim 1 or claim 2, wherein the second recess is provided above the first recess.

4. The aforementioned tube has a cylindrical shape, The fuel cell stack according to claim 1 or claim 2, wherein the first wall surface has a planar shape that is approximately semicircular or approximately crescent-shaped in approximately the lower half of the first recess.

5. The fuel cell stack according to claim 1 or 2, wherein the second recess extends outward from a corresponding position on the outer edge of the first recess and includes a lateral extension that communicates directly with the cooling medium discharge channel.

6. The fuel cell stack according to claim 1 or claim 2, wherein the end receiving portion is located above the cooling medium discharge channel.

7. The second end unit has, in order from the side of the cell laminate, a terminal plate, an electrical insulation plate, and an end plate. The electrical insulating plate has the end receiving portion, The fuel cell stack according to claim 1 or claim 2, wherein the terminal plate has a support hole through which the pipe body passes and an opening that opens the second recess toward the cooling medium discharge channel.

8. The fuel cell stack according to claim 7, wherein the support hole is larger than the outer dimensions of the pipe.

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