CN214588936U

CN214588936U - Fuel cell stack

Info

Publication number: CN214588936U
Application number: CN202120550277.7U
Authority: CN
Inventors: 福井阳一; 井上直树; 池田佑太
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2021-03-17
Filing date: 2021-03-17
Publication date: 2021-11-02
Anticipated expiration: 2031-03-17

Abstract

The utility model provides a fuel cell stack can prevent that comdenstion water etc. from getting into fuel cell stack reliably. A fuel cell stack comprising: the battery cell stack includes a cell stack including a plurality of power generating cells stacked together, an end unit, and a dummy cell that is disposed on the end unit side and does not have power generating capability. At least the cell stack and the end unit are provided with a reactant gas supply passage, a first reactant gas discharge passage, and a second reactant gas discharge passage. A bypass flow path is formed between the cell stack and the end unit to connect the reactant gas supply passage and the first reactant gas discharge passage. The end unit is formed with an annular projection projecting from the periphery of the reactant gas supply passage, the annular projection having an outer diameter smaller than the inner diameter of the reactant gas supply passage and extending in a direction away from the reactant gas supply passage, and the annular projection having a distance from the root to the tip thereof greater than a distance from the root to an end of the end unit on the dummy cell side.

Description

Fuel cell stack

Technical Field

The utility model relates to a fuel cell stack.

Background

In prior art document 1, in order to prevent dew condensation water and the like from entering a cell stack (power generation cell) constituting a fuel cell stack and adversely affecting the stability of power generation and the durability of a membrane/electrode, a water discharge bypass flow path extending laterally from a gas discharge passage is provided in the vicinity of a gas supply passage. The bypass flow path extends from the lower portion of the annular projection as a space formed between the inner insulating plate and the outer insulating plate. Further, according to this structure, the dew condensation water is required to rise in the annular projection against the gravity in order to enter the gas supply communication holes of the inner insulating plates, and the dew condensation water and the like can be prevented from entering the cell stack (power generation cell) constituting the fuel cell stack.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2019-175673

SUMMERY OF THE UTILITY MODEL

The utility model provides a fuel cell stack can prevent that comdenstion water etc. from getting into fuel cell stack reliably.

The utility model provides a fuel cell stack, include: a single cell laminate body in which a plurality of power generating single cells are laminated, the power generating single cells having an electrolyte-electrode structure and a separator sandwiching the electrolyte-electrode structure, the electrolyte-electrode structure having an anode electrode and a cathode electrode disposed on both sides of an electrolyte; an end unit including terminal plates, insulating plates, and end plates disposed at both ends of the cell stack; and a dummy cell that is disposed on the end unit side and does not have power generation energy. The fuel cell stack has a reactant gas supply passage formed at least in the cell stack body and the end unit, for supplying a reactant gas extending in the stacking direction to be supplied to the anode or the cathode; and a first reactant gas discharge passage and a second reactant gas discharge passage that discharge a used reactant gas discharged from the anode electrode or the cathode electrode, wherein the reactant gas supply passage is formed at one end portion of the cell stack in the horizontal direction, and the first reactant gas discharge passage and the second reactant gas discharge passage are formed at the other end portion of the cell stack in the horizontal direction, and wherein the first reactant gas discharge passage is located at a position lower than the reactant gas supply passage, and the second reactant gas discharge passage is located at a position higher than the reactant gas supply passage. Further, a bypass flow path is formed between the cell stack and the end unit to connect the reactant gas supply passage and the first reactant gas discharge passage. The end unit is formed with an annular projection projecting from the periphery of the reactant gas supply passage, the annular projection extending in a direction away from the reactant gas supply passage, and a distance from a root of the annular projection to a tip of the annular projection is greater than a distance from the root of the annular projection to an end of the end unit on the dummy cell side.

In an embodiment of the present invention, the bypass flow path is formed below the annular convex portion, and the root side of the annular convex portion is used as a starting point.

In view of the above, in the fuel cell stack of the present invention, even when a large amount of dew condensation water is generated and the dew condensation water passes over the annular convex portion, the dew condensation water may flow through the upper surface of the annular convex portion to the gap before the dew condensation water passes toward the idle battery side, and the dew condensation water may be disposed in correspondence with the virtual monocell. Further, the dew condensation water is less likely to splash in a state where the dew condensation water has a large mass, and does not flow over the dummy cell and enter the power generation cell. In this way, the dew condensation water in the end unit can be discharged to the outside through the bypass flow path by providing the bypass flow path and the dummy cells, and the dew condensation water can be prevented from splashing to the power generating cells. This prevents dew condensation water from entering the power generation cell from the oxygen-containing gas supply passage of the cell stack. Therefore, it is possible to avoid the shortage of the supply of the oxidizing gas in each power generating cell (reaction gas) due to the blocking of the oxidizing gas channel (reaction gas channel) in the cell stack. Therefore, it is possible to effectively prevent the cell voltage from becoming unstable or the cell voltage from decreasing to cause a decrease in power generation performance. In addition, it is also possible to prevent the electrolyte membrane and the electrode catalyst from deteriorating or the separator from corroding due to water remaining in the cell stack. Therefore, there is an advantage in that the life of the fuel cell stack is prolonged.

In order to make the aforementioned and other features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is an overall schematic perspective view of a fuel cell stack according to an embodiment of the present invention;

fig. 2 is an exploded perspective view of the power generating cell;

fig. 3 is a structural explanatory view of the first metal separator as viewed from the oxidant gas flow path side;

fig. 4 is a schematic sectional view of the fuel cell stack along the stacking direction (the direction of arrow a);

fig. 5 is a schematic front view showing an end face of an inner insulating plate, which constitutes an end unit of the fuel cell stack of fig. 1, on a side facing an outer insulating plate.

Description of reference numerals:

10: a fuel cell stack;

12: a power generation cell;

12 a: a virtual cell;

14: a single cell laminate;

28: an electrolyte membrane-electrode assembly unit;

28 a: an electrolyte membrane-electrode structure;

33: engaging the separator;

40: an electrolyte membrane;

42: an anode electrode;

44: a cathode electrode;

16a, 16 b: a terminal plate;

18. 19: an insulating plate;

20a, 20 b: an end plate;

34 a: an oxidant gas supply communication hole;

34b 1: an upper side oxidant gas discharge communication hole;

34b 2: a lower oxidant gas discharge communication hole;

38 a: a fuel gas supply communication hole;

38b 1: an upper fuel gas discharge communication hole;

38b 2: a lower fuel gas discharge communication hole;

92: an annular projection;

92 a: a root portion;

92 b: a top portion;

94: a bypass flow path;

e: an end portion;

EU: an end unit.

Detailed Description

Fig. 1 is a schematic perspective view of the entire fuel cell stack according to an embodiment of the present invention, fig. 2 is an exploded perspective view of a power generation unit cell, fig. 3 is an explanatory view of the structure of a first metal separator as viewed from the oxidant gas flow path side, fig. 4 is a schematic cross-sectional view of the fuel cell stack along the stacking direction (arrow a direction), and fig. 5 is a schematic front view showing an end face of an inner insulating plate facing an outer insulating plate constituting an end unit of the fuel cell stack of fig. 1. The specific structure of the fuel cell stack 10 will be described below with reference to fig. 1 to 5.

Referring to fig. 1, in the present embodiment, a fuel cell stack 10 includes a cell stack 14 in which a plurality of power generation cells 12 are stacked in a horizontal direction (the direction of arrow a), an end unit EU, and a dummy cell 12a disposed on the side of the end unit EU. The fuel cell stack 10 is mounted on a fuel cell vehicle such as a fuel cell electric vehicle, not shown. The arrow B direction is a horizontal direction perpendicular to the arrow a direction, and the arrow C direction is a vertical direction (gravity direction).

The end unit EU includes

terminal plates

16a and 16b, an inner insulating plate (second insulating plate) 17, outer insulating plates (insulating plates) 18 and 19, and

end plates

20a and 20b, respectively, which are disposed at both ends of the cell stack 14. The end unit EU at one end of the cell stack 14 in the stacking direction (the direction of arrow a) includes, in order from the inside toward the outside, a terminal plate 16a for taking out electric power, an inner insulating plate (second insulating plate) 17, an outer insulating plate 18 (insulating plate), and an end plate 20 a. The end unit EU at the other end in the stacking direction of the cell stack 14 includes a terminal plate 16b, an insulating plate 19, and an end plate 20b in this order from the inside toward the outside.

The

terminal plates

16a and 16b are current collectors, and the anode 42 (or the cathode 44) of each power generation cell 12 is electrically connected to the terminal plate 16 a. On the other hand, the cathode 44 (or the anode 42) of each power generation cell 12 is electrically connected to the terminal plate 16 b. In addition, fig. 2 shows an anode electrode 42 and a cathode electrode 44.

Terminal portions

22a and 22b are formed to protrude outward in the stacking direction at substantially the center of each of

terminal plates

16a and 16 b. The

terminal portions

22a and 22b have a substantially cylindrical shape, and most of the side walls thereof are covered with an insulating cylindrical body, not shown. The insulating cylindrical body is sandwiched between the

terminal portions

22a and 22b and the inner walls of the through holes 24 formed in the inner insulating plate 17, the outer insulating plate 18, the insulating plate 19, and the

end plates

20a and 20b, and particularly, electrically insulates the

terminal portions

22a and 22b from the

end plates

20a and 20 b. The distal ends of the

terminal portions

22a and 22b, which are not covered with the insulating cylindrical bodies, are exposed outward in the stacking direction of the

end plates

20a and 20 b.

The inner insulating plate (second insulating plate) 17 and the insulating plate 19 are made of an insulator, and a recess 26 recessed outward in the stacking direction is formed in the center of the end surface on the inner side in the stacking direction. The

terminal plates

16a, 16b are housed in the respective recesses 26.

The outer insulating plate (insulating plate) 18 is also formed of an insulator. The inner insulating plate 17, the outer insulating plate 18, and the insulating plate 19 are formed of an electrically insulating resin such as a Polycarbonate (PC) resin or a phenol resin, for example.

The

end plates

20a and 20b have a horizontally long (or vertically long) rectangular shape, and a connecting rod 27 is disposed between the sides. Both ends of each connecting rod 27 are fixed to the inner surfaces of the

end plates

20a, 20b, and a fastening load in the stacking direction (the direction of arrow a) is applied to the cell stack 14. Instead of this configuration, the cell stack 14 may be housed in a casing having

end plates

20a and 20b as end side plates.

As shown in fig. 2, the membrane electrode assembly unit 28 is sandwiched by a first metal separator 30 and a second metal separator 32, thereby constituting the power generating cell 12. The first metal separator 30 and the second metal separator 32 are formed by press-forming a cross section of a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a thin metal plate having a surface treatment for corrosion prevention applied to a metal surface thereof into a corrugated shape, for example. The first metal separator 30 and the second metal separator 32 are integrally joined together by welding, brazing, caulking, or the like to the outer peripheries thereof, thereby constituting a joined separator 33.

The membrane electrode assembly unit 28 includes a membrane electrode assembly 28a as an electrolyte electrode assembly, and a resin frame member 46 joined to and surrounding an outer peripheral portion of the membrane electrode assembly 28 a. The membrane electrode assembly 28a includes an electrolyte membrane 40, an anode electrode 42 provided on one surface of the electrolyte membrane 40, and a cathode electrode 44 provided on the other surface of the electrolyte membrane 40.

The electrolyte membrane 40 is formed of, for example, a solid polymer electrolyte membrane (cation exchange membrane). The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water. The electrolyte membrane 40 is sandwiched by an anode electrode 42 and a cathode electrode 44. In addition, the electrolyte membrane 40 can use not only a fluorine-based electrolyte but also an HC (hydrocarbon) -based electrolyte.

Although not shown in detail, the anode 42 includes a first electrode catalyst layer joined to one surface of the electrolyte membrane 40, and a first gas diffusion layer laminated on the first electrode catalyst layer. The cathode 44 includes a second electrode catalyst layer joined to the other surface of the electrolyte membrane 40, and a second gas diffusion layer laminated on the second electrode catalyst layer.

As shown in fig. 3, an oxidizing gas channel 48 extending, for example, in the direction of arrow B is provided on a surface 30a of the first metal separator 30 facing the membrane electrode assembly unit 28. The oxygen-containing gas flow field 48 communicates with the oxygen-containing gas supply passage 34a, the upper oxygen-containing gas discharge passage 34b1, and the lower oxygen-containing gas discharge passage 34b 2. The oxidizing gas channel 48 has a linear channel groove (or a wavy channel groove) 48B between a plurality of projections 48a extending in the direction indicated by the arrow B.

On the other hand, on a surface 32a of the second metal separator 32 facing the membrane electrode assembly unit 28, a fuel gas flow field 58 is formed, for example, extending in the direction of arrow B. The fuel gas flow field 58 communicates with the fuel gas supply passage 38a, the upper fuel gas discharge passage 38b1, and the lower fuel gas discharge passage 38b 2. The fuel gas flow field 58 has straight flow grooves (or wave-shaped flow grooves) 58B between a plurality of projections 58a extending in the direction indicated by the arrow B.

Between the surface 30b of the first metal separator 30 and the surface 32a of the second metal separator 32 joined to each other by welding or brazing, a coolant flow field 66 is formed which communicates with the upper coolant supply passage 36a1, the lower coolant supply passage 36a2, the upper coolant discharge passage 36b1, and the lower coolant discharge passage 36b 2. The coolant flow field 66 is formed by overlapping the shape of the back surface of the first metal separator 30 having the oxidant gas flow field 48 and the shape of the back surface of the second metal separator 32 having the fuel gas flow field 58.

Similarly to the cell stack 14, the end plate 20a, the outer insulating plate 18, and the inner insulating plate 17 are provided with an upper fuel gas discharge passage 38B1 (second reactant gas discharge passage), an upper coolant discharge passage 36B1, an oxygen-containing gas supply passage 34a (reactant gas supply passage), a lower coolant discharge passage 36B2, and a lower fuel gas discharge passage 38B2 (first reactant gas discharge passage) extending in the direction indicated by the arrow a at one end in the direction indicated by the arrow B (horizontal direction) perpendicular to the direction indicated by the arrow a, which is the stacking direction. These communication holes are arranged in a line in the direction of gravity, i.e., the arrow C direction, but may be arranged in a so-called zigzag pattern.

The upper fuel gas discharge passage 38b1 and the lower fuel gas discharge passage 38b2 discharge a fuel gas, such as a hydrogen-containing gas, as one of the reactant gases. The oxygen-containing gas supply passage 34a supplies an oxygen-containing gas as the other reactant gas. The upper coolant discharge passage 36b1 and the lower coolant discharge passage 36b2 discharge appropriate coolants such as water, oil, and glycol.

The oxygen-containing gas supply passage 34a is disposed between the upper coolant discharge passage 36b1 and the lower coolant discharge passage 36b 2. The upper fuel gas discharge passage 38b1 is disposed above the upper coolant discharge passage 36b1, and the lower fuel gas discharge passage 38b2 is disposed below the lower coolant discharge passage 36b 2.

At the other end of the fuel cell stack 10 in the direction indicated by the arrow B, an upper oxygen-containing gas discharge passage 34B1 (a second reactant gas discharge passage), an upper coolant supply passage 36a1, a fuel gas supply passage 38a (a reactant gas supply passage), a lower coolant supply passage 36a2, and a lower oxygen-containing gas discharge passage 34B2 (a first reactant gas discharge passage) are provided, which extend in the direction indicated by the arrow a. These communication holes are arranged in a line in the direction of gravity, i.e., the arrow C direction, but may be arranged in a so-called zigzag pattern.

The fuel gas supply passage 38a supplies the fuel gas discharged from the upper fuel gas discharge passage 38b1 and the lower fuel gas discharge passage 38b 2. The upper coolant supply passage 36a1 and the lower coolant supply passage 36a2 supply the coolant discharged from the upper coolant discharge passage 36b1 and the lower coolant discharge passage 36b 2. The upper oxygen-containing gas discharge passage 34b1 and the lower oxygen-containing gas discharge passage 34b2 discharge the oxygen-containing gas supplied from the oxygen-containing gas supply passage 34 a.

The fuel gas supply passage 38a is disposed between the upper coolant supply passage 36a1 and the lower coolant supply passage 36a2 that are vertically separated from each other. The upper oxygen-containing gas discharge passage 34b1 is disposed above the upper coolant supply passage 36a1, and the lower oxygen-containing gas discharge passage 34b2 is disposed below the lower coolant supply passage 36a 2.

That is, in the present embodiment, the oxygen-containing gas supply passage 34a through which the oxygen-containing gas is supplied, and the upper oxygen-containing gas discharge passage 34b1 and the lower oxygen-containing gas discharge passage 34b2 through which the oxygen-containing gas is discharged are formed at opposite ends with respect to each other with the terminal portion 22a interposed therebetween. The lower oxygen-containing gas discharge passage 34b2 is located lower than the oxygen-containing gas supply passage 34a, and the upper oxygen-containing gas discharge passage 34b1 is located higher than the oxygen-containing gas supply passage 34 a. Similarly, the fuel gas supply passage 38a, the lower fuel gas discharge passage 38b2, and the upper fuel gas discharge passage 38b1 are formed at opposite ends with the terminal portion 22a interposed therebetween, and the lower fuel gas discharge passage 38b2 is located at a position lower than the fuel gas supply passage 38a, and the upper fuel gas discharge passage 38b1 is located at a position higher than the fuel gas supply passage 38 a.

The upper fuel gas discharge passage 38b1 and the lower fuel gas discharge passage 38b2 are connected to each other via a first communication path, not shown, provided in the insulating plate 19, for example. Similarly, the upper oxygen-containing gas discharge passage 34b1 and the lower oxygen-containing gas discharge passage 34b2 may be communicated with each other via a second communication path, not shown, provided in the insulating plate 19, for example. The first and second communication passages may be provided in the terminal plate 16b or the end plate 20 b.

A manifold 80 (reaction gas supply piping member) shown in fig. 4 is attached to a part of the end plate 20 a. Fig. 4 shows the oxidizing gas supply pipe portion 82, and the inside thereof is an oxidizing gas supply passage 84.

The outlet end of the oxygen-containing gas supply pipe portion 82 overlaps the oxygen-containing gas supply passage 34a of the end plate 20 a. Therefore, the oxygen-containing gas supply flow field 84 communicates with the oxygen-containing gas supply passage 34 a. The oxygen-containing gas supply passage 34a may have a cylindrical shape.

Here, as shown in fig. 4, an annular projection 92 is formed to protrude from the inner insulating plate 17 near the inlet of the oxygen-containing gas supply passage 34a, and the annular projection 92 extends in a direction away from the oxygen-containing gas supply passage 34 a. The annular projection 92 has a dimension in the vertical direction (direction C) and a dimension in the lateral direction (direction a) smaller than the dimension in the vertical direction and the dimension in the lateral direction of the oxygen-containing gas supply passage 34a of the outer insulating plate 18, and the tip thereof enters the oxygen-containing gas supply passage 34a of the outer insulating plate 18. When the oxygen-containing gas supply passage 34a provided in the outer insulating plate 18 is circular, the outer diameter of the annular projection 92 may be smaller than the inner diameter of the oxygen-containing gas supply passage 34 a. Further, a distance L1 from the root 92a of the annular convex portion 92 to the top 92b of the annular convex portion 92 is greater than a distance L2 from the root 92a of the annular convex portion 92 to the end E of the end unit EU on the dummy cell 12a side.

As shown in fig. 5, a groove-shaped bypass flow path 94 extending from below the oxygen-containing gas supply passage 34a to the side of the lower oxygen-containing gas discharge passage 34b2 is formed in the end surface of the inner insulating plate 17 on the side facing the outer insulating plate 18. That is, the bypass passage 94 is formed below the annular projection 92 and extends as a gap formed between the inner insulating plate 17 and the outer insulating plate 18 with the root portion 92a side of the annular projection 92 as a starting point. A sealing member, not shown, is provided outside the bypass flow path 94.

As shown in fig. 5, since the oxygen-containing gas supply passage 34a is located higher than the lower oxygen-containing gas discharge passage 34B2, the bypass channel 94 is inclined so as to descend from the oxygen-containing gas supply passage 34a toward the lower oxygen-containing gas discharge passage 34B2 with respect to the direction indicated by the arrow B.

In the present embodiment, as shown in fig. 1, the outer edge of terminal plate 16a in the direction of arrow B is located inward of the ten communication holes. The terminal plate 16a may be provided with the ten communication holes by increasing the dimension of the terminal plate 16a in the direction indicated by the arrow B.

The fuel cell stack 10 according to the present embodiment is basically configured as described above, and its operational effects will be described below.

As shown in fig. 1, when the fuel cell stack 10 is operated, an oxygen-containing gas, for example, compressed air, is supplied to the oxygen-containing gas supply passage 34a of the end plate 20 a. On the other hand, a fuel gas such as a hydrogen-containing gas, for example, hydrogen gas is supplied to the fuel gas supply passage 38a of the end plate 20 a. Further, the coolant such as pure water, ethylene glycol, oil, or the like is supplied to the upper coolant supply passage 36a1 and the lower coolant supply passage 36a2 of the end plate 20 a.

As shown in fig. 2, the fuel gas is introduced from the fuel gas supply passage 38a into the fuel gas flow field 58 of the second metal separator 32. The fuel gas moves in the direction indicated by the arrow B along the fuel gas flow field 58 and is supplied to the anode 42 of the membrane electrode assembly 28 a.

On the other hand, as shown in fig. 3, the oxygen-containing gas is introduced from the oxygen-containing gas supply passage 34a into the oxygen-containing gas flow field 48 of the first metal separator 30. The oxidizing gas moves in the direction indicated by the arrow B along the oxidizing gas channel 48, and is supplied to the cathode 44 of the membrane electrode assembly 28 a.

Therefore, in each membrane electrode assembly 28a, the fuel gas supplied to the anode 42 and the oxidant gas supplied to the cathode 44 are consumed by the electrochemical reaction in the first electrode catalyst layer and the second electrode catalyst layer, and power generation is performed. The coolant supplied to the upper coolant supply passage 36a1 and the lower coolant supply passage 36a2 is introduced into the coolant flow field 66 formed between the first metal separator 30 and the second metal separator 32, and then flows in the direction indicated by the arrow B. After cooling the membrane electrode assembly 28a, the coolant is discharged from the upper coolant discharge passage 36b1 and the lower coolant discharge passage 36b 2.

External loads such as motors are electrically connected to the

terminal portions

22a and 22 b. The electric power resulting from the power generation of the fuel cell stack 10 is consumed by the external load.

The fuel gas (post-use reactant gas) supplied to and consumed by the anode 42 is distributed to the upper fuel gas discharge passage 38b1 and the lower fuel gas discharge passage 38b2, and flows in the direction of arrow a and is discharged. The oxygen-containing gas (reactant gas after use) supplied to and consumed by the cathode 44 is distributed to the upper oxygen-containing gas discharge passage 34b1 and the lower oxygen-containing gas discharge passage 34b2, and flows in the direction indicated by the arrow a and is discharged.

Here, in order to keep the electrolyte membrane 40 in a wet state, the oxidant gas is humidified by adding water thereto before supplying the oxidant gas to the fuel cell stack 10. For example, when the fuel cell stack 10 stops operating and becomes low in temperature, the moisture condenses in the oxidizing gas supply pipe portion 82 (see fig. 4) of the manifold 80, and as a result, the dew condensation water W is generated and flows to the outer insulating plates 18 through the oxidizing gas supply pipe portion 82. The dew condensation water W reaching the outlet end (downstream side opening) of the oxidizing gas supply pipe portion 82 is subjected to gravity. That is, the condensed water W is likely to drip down to the inner wall of the oxygen-containing gas supply passage 34a of the outer insulating plate 18 by gravity.

The vertical dimension and the lateral dimension of the annular projection 92 provided in the vicinity of the oxygen-containing gas supply passage 34a of the inner insulating plate 17 are smaller than the vertical dimension and the lateral dimension of the oxygen-containing gas supply passage 34a of the outer insulating plate 18. Therefore, the dew condensation water W dropped on the inner wall of the oxygen-containing gas supply passage 34a of the outer insulating plate 18 needs to rise in the annular projection 92 against gravity in order to enter the oxygen-containing gas supply passage 34a of the inner insulating plate 17. Therefore, the condensed water W dropped on the inner wall of the oxygen-containing gas supply passage 34a of the outer insulating plate 18 is less likely to travel to the downstream side of the oxygen-containing gas supply passage 34 a.

On the other hand, as described above, the distance L1 from the root 92a of the annular convex portion 92 to the apex 92b of the annular convex portion 92 is greater than the distance L2 from the root 92a of the annular convex portion 92 to the end E of the end unit EU on the dummy cell 12a side, and the bypass flow path 94 is formed below the annular convex portion 92 with the root 92a side of the annular convex portion 92 as the starting point. The dew condensation water W is likely to flow downward by gravity and intrude into the bypass flow path 94. The dew condensation water W is sent to the lower oxygen-containing gas discharge passage 34b2 (see fig. 5) through the bypass flow field 94, and thereafter discharged to the outside from the end plate 20 a. Further, even when a large amount of dew condensation water W is generated and the dew condensation water W passes over the annular convex portion 92 due to the arrangement of the annular convex portion 92 having a long distance, the dew condensation water W flows over the upper surface of the annular convex portion 92 and flows into the gap before the idle battery side, and the virtual cells 12a can be handled by the arrangement of the virtual cells 12 a. Further, the dew condensation water W is less likely to splash in a state where the dew condensation water W has a large mass, and does not flow over the dummy cell 12a and enter the power generation cell 12. In this way, the dew condensation water W in the end unit passes through the bypass flow path 94 and the dummy cells 12a, and the dew condensation water W on the wall surface is discharged to the outside through the bypass flow path 94, and the dew condensation water W is prevented from splashing to the power generation cells 12. Further, since the volume of the peripheral portion of the annular convex portion 92 can serve as a buffer space for accommodating the dew condensation water W, that is, when the dew condensation water W flows below the annular convex portion 92, the flow rate of the dew condensation water W can be close to a constant level, and a large amount of dew condensation water W is not concentrated in the bypass flow path 94, the drainage performance of the bypass flow path 94 can be improved.

This prevents the dew condensation water W from entering the power generation cell 12 from the oxygen-containing gas supply passage 34a of the cell stack 14. Therefore, it is possible to avoid the shortage of the supply of the oxidizing gas in each power generating cell 12 (reaction gas) due to the blocking of the oxidizing gas flow field 48 (reaction gas flow field) in the cell stack 14. Therefore, it is possible to effectively prevent the cell voltage from becoming unstable or the cell voltage from decreasing to cause a decrease in power generation performance. In addition, it is also possible to prevent the electrolyte membrane and the electrode catalyst from deteriorating or the separators from corroding due to water remaining in the cell laminate 14. Therefore, there is an advantage in that the life of the fuel cell stack 10 is prolonged.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, the bypass flow field 94 may be provided from the fuel gas supply passage 38a to the lower fuel gas discharge passage 38b 2.

Further, a groove-like bypass flow passage 94 may be formed in an end surface of the outer insulating plate 18 facing the inner insulating plate 17.

Further, both the bypass channel 94 extending from the oxygen-containing gas supply passage 34a to the lower oxygen-containing gas discharge passage 34b2 and the bypass channel 94 extending from the fuel gas supply passage 38a to the lower fuel gas discharge passage 38b2 may be provided. In this case, one bypass passage 94 is formed in the inner insulating plate 17, and the other bypass passage 94 is formed in the outer insulating plate 18. When the two bypass channels 94 form an intersection, a lid may be provided at the intersection in order to avoid mixing of the two reaction gases at the intersection.

As described above, in the fuel cell stack according to the present invention, even when a large amount of dew condensation water is generated and the dew condensation water passes over the annular projection, the dew condensation water flows over the upper surface of the annular projection and flows into the gap before the dew condensation water passes toward the dead cell side, and the virtual cells can be disposed. Further, the dew condensation water is less likely to splash in a state where the dew condensation water has a large mass, and does not flow over the dummy cell and enter the power generation cell. In this way, the dew condensation water in the end unit can be discharged to the outside through the bypass flow path by providing the bypass flow path and the dummy cells, and the dew condensation water can be prevented from splashing to the power generating cells. This prevents dew condensation water from entering the power generation cell from the oxygen-containing gas supply passage of the cell stack. Therefore, it is possible to avoid the shortage of the supply of the oxidizing gas in each power generating cell (reaction gas) due to the blocking of the oxidizing gas channel (reaction gas channel) in the cell stack. Therefore, it is possible to effectively prevent the cell voltage from becoming unstable or the cell voltage from decreasing to cause a decrease in power generation performance. In addition, it is also possible to prevent the electrolyte membrane and the electrode catalyst from deteriorating or the separator from corroding due to water remaining in the cell stack. Therefore, there is an advantage in that the life of the fuel cell stack is prolonged.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications or substitutions do not depart from the scope of the embodiments of the present invention, and the essence of the corresponding technical solutions is not disclosed.

Claims

1. A fuel cell stack, comprising: a single cell laminate in which a plurality of power generating single cells are laminated, the power generating single cells having an electrolyte-electrode structure and a separator sandwiching the electrolyte-electrode structure, the electrolyte-electrode structure having an anode electrode and a cathode electrode disposed on both sides of an electrolyte; an end unit including terminal plates, insulating plates, and end plates disposed at both ends of the cell stack; and a dummy cell which is arranged on the side of the end unit and does not have power generation energy, and the fuel cell stack,

a reactant gas supply passage extending in the stacking direction and supplying a reactant gas to the anode or the cathode is formed at least in the cell stack and the end unit; and a first reactant gas discharge passage and a second reactant gas discharge passage for discharging a used reactant gas discharged from the anode electrode or the cathode electrode,

wherein the reactant gas supply passage is formed at one end portion of the cell stack in the horizontal direction, and the first reactant gas discharge passage and the second reactant gas discharge passage are formed at the other end portion of the cell stack in the horizontal direction,

and the first reactant gas discharge passage is located at a position lower than the reactant gas supply passage, and the second reactant gas discharge passage is located at a position higher than the reactant gas supply passage,

further, a bypass flow path is formed between the cell stack and the end unit to connect the reactant gas supply passage and the first reactant gas discharge passage,

the end unit has an annular projection projecting from the periphery of the reactant gas supply passage and extending in a direction away from the reactant gas supply passage,

the distance from the root of the annular projection to the top of the annular projection is greater than the distance from the root of the annular projection to the end of the end unit on the virtual cell side.

2. The fuel cell stack according to claim 1, wherein the bypass flow path is formed below the annular convex portion, and starts at a root side of the annular convex portion.