Fuel cell stack

Abstract

The goal is to ensure that bubbles that flow into the bubble discharge hole without flowing through the main tube are reliably discharged, and that the air vent tube does not become difficult to remove from the bubble discharge hole. [Solution] The bubble discharge hole 110 constituting the front end receiving portion 90 comprises a first portion 112 provided on the cell stack 14 side, which is larger than the outer shape of the pipe body 80 and longer in the vertical direction, which displaceably receives the front end 80A of the pipe body 80 and communicates with the internal passage 82 of the pipe body 80; a second portion 114 provided on the side opposite to the cell stack 114, which communicates with the first portion 112 and the internal passage 82 and has a vertical dimension H2 that is larger than the outer diameter R1 of the pipe body 80; and an annular contact surface 116 provided at the boundary between the first portion 112 and the second portion 114 and facing the front end surface 81 of the pipe body 80.

Description

Technical Field

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

Background Art

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

[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 the 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 tube, is arranged in the cooling medium discharge flow path is known (for example, Patent Document 1).

[0004] The air vent tube extends in the stacking direction of the power generation cells in the cell stack in the cooling medium discharge flow path, and both ends are supported by end units arranged at the ends of the fuel cell stack. The support structure of the air vent tube by the end units preferably allows for manufacturing during assembly to tolerate stacking errors or the like of each power generation cell in the cell stack. For this reason, the air vent tube 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 tolerating stacking errors or the like.

[0005] The ends of the air vent tube are fitted into air bubble discharge holes formed in the end units so as to be displaceable in the radial direction and the longitudinal direction. Bubbles captured in the air vent tube are discharged from the air bubble discharge holes to the outside of the fuel cell stack.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-79779 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the fuel cell stack described above, air bubbles in the cooling medium discharge channel may flow directly into the bubble discharge hole without passing through the air vent pipe. In this case, if the discharge hole is a tapered hole, the air vent pipe may fit tightly into the bubble discharge hole, potentially blocking communication between the upstream and downstream sides of the bubble discharge hole. Such blocking can cause air bubbles to accumulate upstream of the discharge hole, hindering their discharge.

[0008] In the fuel cell stack described above, when the air vent pipe is fitted into the bubble discharge hole, its axial movement is restricted. However, if the fitting is too tight, there is a risk that the air vent pipe may have difficulty coming out of the bubble discharge hole.

[0009] In view of the above background, the present invention aims to prevent bubbles from accumulating in the bubble discharge hole (tube) and to restrict the axial displacement of the air vent pipe without causing other problems. This will ultimately contribute to energy efficiency. [Means for solving the problem]

[0010] 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 and having its ends supported by the first end unit and the second end unit, wherein the first end unit has an end receiving portion of the tubular body, and the end receiving portion supports the first end unit in the stacking direction The tube has a bubble discharge hole that penetrates through it, and the bubble discharge hole has a first portion provided on the cell stack side, which is larger than the outer shape of the tube and longer in the vertical direction, which receives 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 which communicates with the internal passage of the tube; a second portion provided on the side opposite to the cell stack, which communicates with the first portion and the internal passage, which includes a portion smaller than the outer shape of the tube and has a vertical dimension larger than the vertical dimension of the tube; and an annular contact surface provided at the boundary between the first portion and the second portion, which faces one end face of the tube and into which one end face of the tube can abut. [Effects of the Invention]

[0011] According to the present invention, bubbles do not accumulate in the bubble discharge holes, and the axial displacement of the pipe body is restricted without causing other problems. [Brief explanation of the drawing]

[0012] [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 longitudinal cross-sectional view of the main part of the fuel cell stack according to this embodiment. [Figure 4] Cross-sectional view along line IV-IV in Figure 3 according to this embodiment [Figure 5] Cross-sectional view along line IV-IV in Figure 3 with the tubing removed. [Figure 6] Cross-sectional view along line IV-IV in Figure 3, showing the displacement of the pipe. [Figure 7] Enlarged longitudinal section of a key part showing the upward displacement of the pipe body. [Modes for carrying out the invention]

[0013] 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.

[0014] 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).

[0015] The fuel cell stack 10 is supplied with hydrogen gas (fuel gas) and oxidizer gas (air) as reaction gases.

[0016] In the following explanation, the stacking direction of the cell stack 14 may be referred to as the front-to-back direction.

[0017] Each cell laminate 14 includes a rectangular plate-shaped electrolyte membrane-electrode structure 20, a first separator 24 disposed on one side of the electrolyte membrane-electrode structure 20, and a second separator 26 disposed 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 oxidant gas discharge opening 34 are formed to penetrate in the stacking direction in order from top to bottom. On the right edge of each power generation cell 12, an oxidant gas supply opening 36, a refrigerant supply opening 38, and a hydrogen gas discharge opening 40 are formed to penetrate in the stacking direction in order from top to bottom.

[0018] 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 side of the power generation cell 12. On the left edge of the wet-side end unit 16, a hydrogen gas supply opening 48, a refrigerant discharge opening 50, and an oxidant gas discharge opening 52 are formed to penetrate in the front-rear direction in order from top to bottom. On the right edge of the wet-side end unit 16, an oxidant gas supply opening 54, a refrigerant supply opening 56, and a hydrogen gas discharge opening 58 are formed to penetrate in the front-rear direction in order from top to bottom. Each opening provided in the wet-side end unit 16 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] The hydrogen gas supply opening 48 communicates with the hydrogen gas supply opening 30 of the cell laminate 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 laminate 14. The hydrogen gas discharge opening 58 communicates with the hydrogen gas discharge opening 40 of the power generation cell 12.

[0020] 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 hydrogen gas supply openings 61, hydrogen gas discharge openings 67, oxidant gas supply openings 63, oxidant gas discharge openings (not shown), refrigerant supply openings 65, and refrigerant discharge openings (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.

[0021] 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.

[0022] The oxidant gas may be air, 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.

[0023] The refrigerant (cooling medium) may be a liquid containing water or the like, flows in the stacking direction of the cell stack 14 through the refrigerant supply flow path PA5, is supplied to each power generation cell 12, and cools 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 flow path PA6 (cooling medium discharge flow path).

[0024] 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.

[0025] 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, parts corresponding to Figure 1 are given the same reference numerals as those used in Figure 1, and their explanations are omitted.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 supply channel PA5 and 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, above the top of the refrigerant discharge channel PA6. The pipe 80 has a cylindrical shape and includes internal passages 82 that are open at both ends.

[0030] 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.

[0031] In the portion of the cell stack 14 that constitutes the upper side of the refrigerant discharge opening 32, a through hole 88 is formed that penetrates 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.

[0032] 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 4) 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.

[0033] The electrical insulation plate 44 of the wet-side end unit 16 has a front end receiving portion 90 for receiving the front end 80A of the pipe body 80. The electrical insulation plate 44 of the dry-side end unit 18 has a rear end receiving portion 98 for receiving the rear end 80B of the pipe body 80. The rear end receiving portion 98 includes a recessed portion 100 that opens toward the support hole 86 of the terminal plate 60.

[0034] Details of the front end receiving portion 90 will be explained with reference to Figures 3 to 7.

[0035] The front end receiving portion 90 has a bubble discharge hole 110 that penetrates the electrical insulation plate 44 in the stacking direction of the cell stack 14. The bubble discharge hole 110 includes a first portion 112 provided on the cell stack 14 side and a second portion 114 provided on the side opposite to the cell stack 14 than the first portion 112, that is, on the end plate 46 side.

[0036] The first part 112 and the second part 114 are in communication with each other. The first part 112 is in communication with the support hole 84 of the terminal plate 42 on the cell stack 14 side. The second part 114 is in communication with the refrigerant discharge port 92 of the port member 94 provided on the port arrangement plate 45 on the cell stack 14 side (see Figure 2). An airtight sealing member 96 is provided between the port member 94 and the electrical insulation plate 44.

[0037] The first part 112 has an elongated oval or elliptical cross-sectional shape and a tapered shape that narrows towards the second part 114, and communicates with the second part 114 and the internal passage 82 of the pipe body 80.

[0038] The first part 112, as shown in Figure 4, has an outer shape of the tube body 80, in other words, a vertical dimension H1 and a horizontal dimension W1 (left-right dimension) that are larger than the outer diameter R1. That is, H1 > R1 and W1 > R1. As a result, the first part 112 receives the front end 80A of the tube body 80 so that it can be displaced in the stacking direction (axial direction) and in directions perpendicular to the stacking direction (vertical and left-right directions) of the cell stack 14.

[0039] The second part 114 has an oblong or elliptical cross-sectional shape that is long vertically, has a tapered shape that tapers toward the refrigerant discharge port 92 (see FIG. 2), and communicates with the first part 112 and the refrigerant discharge port 92.

[0040] As shown in FIG. 4, the second part 114 has an outer contour shape of the tubular body 80, that is, a vertical dimension H2 larger than the outer diameter R1 and a lateral dimension W2 (left-right dimension) smaller than the outer diameter R1. That is, H2 > R1 and W2 < R1. Thereby, the second part 114 includes portions on both the left and right sides that are smaller than the outer contour shape (outer diameter R1) of the tubular body 80.

[0041] Incidentally, the lateral dimension W1 and the vertical dimension H1 of the first part 112 are dimensions on the expanding end side (the side of the cell laminate 14) of the tapered shape of the first part 112. The vertical dimension H2 and the lateral dimension W2 of the second part 114 are dimensions on the expanding end side (the side of the first part 112) of the tapered shape of the second part 124.

[0042] The front-end receiving portion 90 has an oblong annular contact surface 116 at the boundary between the first part 112 and the second part 124. The contact surface 116 faces the front-end surface 81 of the tubular body 80, has an outer contour larger than the outer contour (outer diameter R1) of the front-end surface 81 of the tubular body 80, and is an annular oblong or elliptical plane that extends in a direction orthogonal to the stacking direction of the cell laminate 14.

[0043] [[ID=​​​​​​

[0045] As shown in Figure 4, half of the difference (H1-H2) between the vertical dimension H1 of the first part 112 and the vertical dimension H2 (expanded dimension) of the second part 124 is smaller than the inner diameter R2 of the pipe body 80. Half of the difference (W1-W2) between the lateral dimension W1 of the first part 112 and the lateral dimension W2 of the second part 124 is smaller than the inner diameter R2 of the pipe body 80. That is, (H1-H2) / 2 <R2、(W1-W2) / 2<R2である。

[0046] Since the second part 114 has a vertical dimension H2 that is larger than the outer diameter R1 (vertical dimension) of the pipe body 80, a gap G (see Figure 4) is formed at the contact surface 116 regardless of the displacement of the pipe body 80 relative to the wet side end unit 16.

[0047] The support hole 84 of the terminal plate 42 is a straight hole with a circular cross-sectional shape. The upper edge 84A of the support hole 84 defines the upper limit of the vertical movement of the tube 80 relative to the cell stack 14 by contact with the tube 80. As shown in Figure 3, the upper edge 84A of the support hole 84 is located vertically α lower than the upper edge 114A of the boundary (expanded end side) of the second part 114 with respect to the first part 112. As a result, even when the tube 80 abuts against the contact surface 116 and is displaced to the upper limit position where it contacts the upper edge 84A of the support hole 84, a gap G of vertical dimension α is secured between the upper edge 114A of the inner surface of the second part 114 and the outer surface of the tube 80.

[0048] According to the above configuration, 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 recessed portion 100 at the rear end receiving portion 98 of the dry-side end unit 18 and enter the internal passage 82 of the pipe body 80. These bubbles flow through the internal passage 82 toward the wet-side end unit 16, through the bubble discharge hole 110 of the wet-side end unit 16, and are discharged to the outside from the refrigerant discharge port 92.

[0049] When the front end surface 81 of the pipe body 80 abuts against the abutting surface 116, the axial displacement of the pipe body 80 in the front side with respect to the wet side end unit 16 is restricted. This restriction is carried out in a state where the outer peripheral surface of the pipe body 80 is loosely fitted to the first part 112 without tightly fitting to the inner peripheral surface of the first part 112, so that problems such as the pipe body 80 being difficult to come out of the air bubble discharge hole 110 do not occur.

[0050] Since the center position C of the second part 114 exists at a position including the internal passage 82 of the pipe body 80 as viewed in the stacking direction of the cell stack 14, as shown by the solid line in FIG. 6, even if the pipe body 80 is displaced upward and leftward with respect to the cell stack 14, or as shown by the phantom line in FIG. 6, even if the pipe body 80 is displaced downward and rightward with respect to the wet side end unit 16, the communication between the internal passage 82 of the pipe body 80 and the second part 114 is maintained.

[0051] Also, since (H1 - H2) / 2 < R2 and (W1 - W2) / 2 < R2, no matter in which direction of the vertical direction and the horizontal direction the pipe body 80 is displaced with respect to the wet side end unit 16, the internal passage 82 is not blocked by the abutment with the abutting surface 116 of the pipe body 80, and the communication between the internal passage 82 of the pipe body 80 and the second part 114 is maintained.

[0052] Thereby, no matter in which direction of the vertical direction and the horizontal direction the pipe body 80 is displaced with respect to the wet side end unit 16, the air bubbles flowing through the internal passage 82 of the pipe body 80 move from the internal passage 82 to the refrigerant discharge port 92, and the discharge of the air bubbles is not inhibited.

[0053] Since the vertical dimension H2 of the second part 114 is larger than the outer diameter R1 (vertical dimension) of the pipe body 80, even if the front end surface 81 of the pipe body 80 abuts against the abutting surface 116, regardless of the vertical and horizontal displacements of the pipe body 80, the communication between the first part 112 and the second part 114 is guaranteed by the gap G. Thereby, the air bubbles that enter the first part 112 from the refrigerant discharge flow path PA6 through the support hole 84 of the terminal plate 42 without flowing through the pipe body 80 flow to the second part 114 and are discharged to the outside.

[0054] In other words, even when the front end surface 81 of the pipe body 80 comes into contact with the contact surface 116, there is always a gap G between the outer surface of the pipe body 80 and the inner surface of the second part 114. As a result, air bubbles that enter the first part 112 can pass through the gap G and flow to the second part 114, regardless of the displacement of the pipe body 80, and be discharged to the outside, without accumulating in the first part 112.

[0055] Since the upper edge 84A of the support hole 84 is located vertically α lower than the upper edge 114A of the boundary between the second part 114 and the first part 112, as shown in Figure 7, even when the front end surface 81 of the tube body 80 abuts against the contact surface 116 and the tube body 80 is displaced to the upper limit position where it abuts against the upper edge 84A of the support hole 84, a gap G connecting the first part 112 and the second part 114 is maintained above the tube body 80, and a space of a size suitable for trapping air bubbles and allowing air bubbles to flow smoothly is maintained in the region of the first part 112 above the tube body 80.

[0056] When the fuel cell stack 10 tilts with the wet end unit 16 facing upwards, and bubbles in the refrigerant flowing through the refrigerant discharge channel PA6 move towards the wet end unit 16, bubbles are generated that flow from the support holes 84 of the terminal plate 42 into the first section 112. These bubbles flow as shown by the streamlines F in Figure 7, collect at the top of the first section 112, and are trapped in the space of the first section 112. The bubbles trapped at the top of the first section 112 flow smoothly through the first section 112, pass through the gap G, and flow to the second section 114. As a result, even when the fuel cell stack 10 tilts with the wet end unit 16 facing upwards, bubbles in the refrigerant are effectively discharged to the outside.

[0057] Furthermore, a space of a suitable size for the smooth flow of bubbles is maintained in the region of the first section 112 above the tubular body 80. As a result, the bubbles that accumulate in the first section 112 do not stagnate in the first section 112 but flow through the gap G to the second section 114. This also ensures that bubbles in the refrigerant are properly discharged to the outside.

[0058] The embodiments are not limited to the above configurations and can be widely modified and implemented. For example, the cross-sectional shapes of the first portion 112 and the second portion 114 of the bubble discharge holes 110 may be vertically long rectangles or the like. The first portion 112 may be a tapered hole, the second portion 114 may be a straight hole, or both the first portion 112 and the second portion 114 may be straight holes. The tubular body 80 may be an elliptical tubular body or a polygonal tubular body.

[0059] (H1 - H2) / 2 < R2, (W1 - W2) / 2 < R2 can also be achieved by restricting the displacement of the tubular body 80 with respect to the wet-side end unit 16 by a stopper and setting their effective vertical dimension and horizontal dimension.

[0060] Finally, summarizing the above embodiments, they can be described as follows.

[0061] One embodiment of a 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 (cooling medium discharge flow path) 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 extending in the stacking direction, with its front end 80A and rear end 80B (ends) supported by the wet-side end unit 16 and the dry-side end unit 18, wherein the wet-side end unit 16 has a front end receiving portion 90 (end receiving portion) of the pipe body 80, and the front end receiving portion 90 is the The tube has a bubble discharge hole 110 that penetrates in the layer direction, and the bubble discharge hole 110 is provided on the cell stack side, is larger than the outer shape of the tube 80 and is long in the vertical direction, and receives the front end 80A (end) of the tube 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 communicates with the internal passage 82 of the tube 80; a second part 114 is provided on the side opposite to the cell stack 14, communicates with the first part 112 and the internal passage 82, includes a portion smaller than the outer shape of the tube 80 and has a vertical dimension H2 that is larger than the outer diameter R1 (vertical dimension) of the tube 80; and an annular contact surface 116 is provided at the boundary between the first part 112 and the second part 114, faces one of the front end surfaces 81 of the tube 80, and can contact one of the front end surfaces 81 of the tube 80.

[0062] In this embodiment, since the second portion 114 of the bubble discharge hole 110 has a vertical dimension larger than the vertical dimension of the pipe body 80, even when the front end surface 81 of the pipe body 80 comes into contact with the contact surface 116, communication between the first portion 112 and the second portion 114 is guaranteed, and bubbles are discharged to the outside without accumulating in the bubble discharge hole 110. When the front end surface 81 of the pipe body 80 comes into contact with the contact surface 116, the axial displacement of the pipe body 80 relative to the wet-side end unit 16 is restricted without the pipe body 80 being tightly fitted into the first portion 112. As a result, the restriction of the axial displacement of the pipe body 80 is performed without causing problems such as the pipe body 80 becoming difficult to remove from the bubble discharge hole 110.

[0063] In the above embodiment, preferably, the central position C of the second portion 114 is located in a position that includes the internal passage 82 when viewed in the stacking direction of the cell laminate 14.

[0064] According to this embodiment, even if the pipe body 80 is displaced radially, including vertically, relative to the wet-side end unit 16, communication between the second portion 114 and the internal passage 82 is guaranteed.

[0065] In the above embodiment, preferably, the wet-side end unit 16 has a support hole 84 in the pipe 80 through which the pipe 80 passes, the support hole 84 is larger than the outer shape of the pipe 80, and the upper edge 84A of the support hole 84 is lower than the upper edge 114A of the boundary of the second portion 114 with respect to the first portion 112.

[0066] According to this embodiment, a large space is maintained above the first portion 112 where bubbles accumulate, allowing for good capture of bubbles above the first portion 112, and consequently, good discharge of bubbles.

[0067] In the above embodiment, preferably, the tube 80 has a cylindrical shape, the first portion 112 and the second portion 114 have vertically elongated oval or elliptical cross-sectional shapes, and the contact surface 116 has vertically elongated oval or elliptical shapes.

[0068] According to this embodiment, the discharge of air bubbles is reliably guaranteed with respect to the vertical displacement of the pipe body 80 relative to the wet-side end unit 16, and the front end surface 81 of the pipe body 80 is stably in contact with the contact surface 116.

[0069] In the above embodiment, preferably, the wet-side end unit 16 has, in order from the side of the cell laminate 14, a terminal plate 42, an electrical insulation plate 44, and an end plate 46, wherein the electrical insulation plate 44 is provided with the bubble discharge hole 110, and the terminal plate 42 is provided with a support hole 84 that supports the pipe body 80 so as to be displaceable in the lamination direction and in a direction perpendicular to the lamination direction.

[0070] In this embodiment, the receiving of the front end 80A of the pipe body 80 and the support of the pipe body 80 are shared between the electrical insulation plate 44 and the terminal plate 42. [Explanation of symbols]

[0071] 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 80: Body 80A: Front end (end) 81: Front end face (end face) 82: Internal passage 84: Support hole 84A: Upper edge 110: Bubble discharge hole 112 :1st part 114:Second part 114A: Upper edge 116: Contact surface C: Center position H2: Vertical dimension R1: Outer diameter (vertical dimension)

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 and having its ends supported by the first end unit and the second end unit, The first end unit has an end receiving portion for the pipe body, and the end receiving portion has a bubble discharge hole that penetrates the first end unit in the stacking direction. The aforementioned bubble discharge hole is A first portion is provided on the cell stack side, is larger than the outer shape of the tube and is long in the vertical direction, and receives 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 communicates with the internal passage of the tube, A second portion is provided on the side opposite to the cell laminate, communicating with the first portion and the internal passage, including a portion smaller than the outer shape of the tube, and having a vertical dimension larger than the vertical dimension of the tube. A fuel cell stack comprising an annular contact surface provided at the boundary between the first portion and the second portion, and facing one end face of the tubular body.

2. The fuel cell stack according to claim 1, wherein the center position of the second portion is located in a position that includes the internal passage when viewed in the stacking direction of the cell stack.

3. The first end unit has a support hole for the pipe through which the pipe passes, The support hole is larger than the outer shape of the pipe body. The fuel cell stack according to claim 1 or claim 2, wherein the upper edge of the support hole is lower than the upper edge of the boundary between the first portion and the second portion.

4. The aforementioned tube has a cylindrical shape, The first and second portions have a vertically elongated oval or elliptical cross-sectional shape. The fuel cell stack according to claim 1 or claim 2, wherein the contact surface has an annular oval or elliptical shape.

5. The first 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 is provided with the bubble discharge holes, The fuel cell stack according to claim 4, wherein the terminal plate is provided with support holes that support the pipe so as to be displaceable in the stacking direction and in a direction perpendicular to the stacking direction.

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