JP2003346830A - Fuel cell stack - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make uniform the in-plane temperature in each power generation cell and to ensure effective power generation performance. A fuel cell stack includes a power generation cell.
And a first cooling cell 18 for cooling the power generation cells 12 with a cooling liquid, and current collecting electrodes 14 and 16 electrically connected integrally to a predetermined number of the power generation cells 12. The first cooling cell 18 supplies a larger amount of cooling medium to the in-plane central portion than the in-plane end portion in a plane corresponding to the power generation surface of the power generation cell 12 to forcibly force the in-plane central portion. It is configured to cool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a joined body comprising an electrolyte sandwiched between an anode electrode and a cathode electrode. The joined body is sandwiched between separators, and fuel gas is supplied to the anode electrode. The present invention relates to a fuel cell stack including a power generation cell for supplying an oxidizing gas to the cathode while supplying the gas.

[0002]

2. Description of the Related Art For example, a phosphoric acid fuel cell (PAFC)
Is a joined body (electrolyte layer / electrode layer) composed of an anode side electrode and a cathode side electrode mainly composed of carbon, on both sides of an electrolyte layer in which concentrated phosphoric acid is impregnated in porous silicon carbide (matrix). An electrode assembly is provided with a power generation cell constituted by sandwiching the electrode assembly with a separator (bipolar plate). Normally, a predetermined number of the power generation cells are stacked and used as a fuel cell stack.

On the other hand, a solid polymer fuel cell (SPFC)
Employs an electrolyte membrane composed of a polymer ion exchange membrane (cation exchange membrane). Similarly, a power generation cell provided with a separator (electrolyte membrane / electrode assembly) composed of the electrolyte membrane and a separator is provided. A predetermined number of the fuel cells are stacked and used as a fuel cell stack.

[0004] In this type of fuel cell stack, a fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter also referred to as a hydrogen-containing gas) is ionized on the catalyst electrode. It moves to the cathode side via the electrolyte. The electrons generated during that time are taken out to an external circuit and used as DC electric energy.
Since an oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas) is supplied to the cathode side electrode, hydrogen ions, electrons, And oxygen react to produce water.

By the way, in the above-mentioned fuel cell, an optimum operating temperature for exhibiting effective power generation performance is set. For example, in the case of a phosphoric acid fuel cell,
° C, and 60 ° C to 90 ° C for the polymer electrolyte fuel cell.
It is. For this reason, it is necessary to maintain the power generation cell at a desired operating temperature, and various cooling structures have conventionally been employed. Generally, a structure is known in which a passage for a cooling medium is formed in a separator constituting a fuel cell stack, and a cooling medium such as water is supplied to the passage to cool a power generation cell.

[0006]

In this case, in water used as a cooling medium or a general cooling medium (cooling liquid) used in a cooling structure for an automobile, impurities such as ions and metal additives are contained. The cooling medium itself has conductivity. On the other hand, even when deionized water or pure water is used as a cooling medium, metal or the like is mixed by circulating through a cooling system pipe or a radiator during operation, and conductivity is imparted to the cooling medium.

However, in the fuel cell stack, electrons generated in each power generation cell are extracted from the current collecting electrodes at both ends of the stack. Electricity flows through As a result, a problem has been pointed out that electricity flows to the cooling system piping, the radiator, and the like via the cooling medium, and a ground fault or a liquid fault occurs, thereby lowering the output of the entire fuel cell stack.

Accordingly, the present applicant has proposed a fuel cell stack that can reliably prevent leakage of electricity through a cooling medium, and that can maintain effective power generation performance with a simple configuration. (See JP-A-2001-332288).

In this fuel cell stack, a cooling cell is interposed between the current collecting electrodes, and a cooling medium supplied to the cooling cell is electrically connected to the power generating cell and the current collecting electrode via an insulating mechanism. And the power generation cells arranged with the cooling cell interposed therebetween or the power generation cells and the current collecting electrode are electrically connected to each other via a conductive mechanism. As a result, it is possible to reliably prevent the occurrence of a ground fault or a liquid shortage through the cooling medium, to effectively prevent a decrease in the output of the entire fuel cell stack, and to maintain a desired power generation function. Become.

By the way, in the above fuel cell stack,
When power is generated by the power generation cell, a temperature distribution may be generated in the in-plane direction of the power generation cell. Specifically, the in-plane temperature of the power generation cell becomes relatively low at the outer peripheral portion that is easily cooled by the atmosphere, while it becomes relatively high at the central portion where heat radiation is difficult. As a result, there is a problem that the in-plane temperature of the power generation cell becomes non-uniform, and the power generation performance in the low temperature portion is lower than the power generation performance at the optimum operating temperature.

The present invention has been made to solve this kind of problem, and in particular, a fuel cell capable of equalizing the in-plane temperature of each power generation cell and ensuring effective power generation performance with a simple and compact configuration. The purpose is to provide a stack.

[0012]

In the fuel cell stack according to the first aspect of the present invention, a cooling cell is interposed between current collecting electrodes, and a cooling medium supplied to the cooling cell is used as a power generation cell and a cooling medium. An insulating mechanism is provided to electrically insulate from the current collecting electrode, and the power generating cells are electrically connected to each other or the power generating cell and the current collecting electrode are electrically connected to each other via a conductive mechanism. The cooling cell is provided with a cooling medium flow path for supplying a larger amount of cooling medium than the in-plane end to the in-plane center in the plane corresponding to the power generation surface.

For this reason, in the in-plane direction of the power generation cell, the central portion, which tends to be relatively high in temperature, is forcibly cooled, while the cooling efficiency of the outer peripheral portion, which tends to be relatively low in temperature, decreases. Therefore, the temperature distribution in the in-plane direction of the power generation cell can be effectively reduced, and the maximum temperature in the in-plane direction can be reduced. Thereby, the temperature difference between the power generation cells in the stacking direction is effectively reduced, and the power generation performance of each power generation cell can be made close to the maximum performance, and the output as the fuel cell stack can be improved satisfactorily.

Further, in the fuel cell stack according to the second aspect of the present invention, the cooling medium flow path is divided into approximately three equal parts at a center part in the plane and both end parts in the plane. A flow rate of １ ／ to ／ of the total flow rate of the cooling medium supplied to the cooling medium flow path is supplied to the central portion. For this reason,
The in-plane temperature of the power generation cell can be made as uniform as possible,
The power generation performance of each power generation cell can be greatly improved.

Further, in the fuel cell stack according to claim 3 of the present invention, a cooling gas for cooling the power generation cells is supplied, and a predetermined number of the power generation cells are interposed between the cooling cells and the cooling gas. An auxiliary cooling cell is interposed therebetween. Therefore, the power generation cell is cooled via the cooling gas supplied to the auxiliary cooling cell.

At this time, an auxiliary cooling cell is interposed between the cooling cells and a predetermined number of power generating cells, that is, in the vicinity of the high-temperature power generating cells between the cooling cells. Therefore, by supplying the cooling gas to the auxiliary cooling cell,
The high-temperature power generation cell near the auxiliary cooling cell can be effectively cooled.

Accordingly, it is possible to maintain the temperature of the power generation cell near the cooling cell at a temperature close to the optimum operation temperature, while cooling the power generation cell near the auxiliary cooling cell to the optimum operation temperature. Thereby, while the temperature of each power generation cell is adjusted to the vicinity of the optimal operation temperature, the temperature difference between the power generation cells along the stacking direction is reduced, and each power generation performance of the power generation cell can be effectively improved. it can.

In addition, at the time of high output, the auxiliary cooling cell is used together with the cooling cell to cool only the power generation cells that need to be cooled. Therefore, there is no need to use a large heat exchanger for cooling, and the heat exchanger can be effectively reduced in size.

[0019]

FIG. 1 is a side view showing a schematic configuration of a fuel cell stack 10 according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the fuel cell stack 10. FIG. 3 is an enlarged sectional view of a main part of the fuel cell stack 10.

The fuel cell stack 10 includes power generation cells 12, and a predetermined number of the power generation cells 12 are stacked in the direction of arrow A. At both ends in the stacking direction of the power generation cell 12, current collecting electrodes 14 and 16 that are electrically connected integrally to the power generation cell 12 are arranged. A predetermined number of first cooling cells 18 are interposed between the current collecting electrodes 14 and 16, and a predetermined number of power generation cells 1 are interposed between the first cooling cells 18.
2 between the current collecting electrodes 14 and 16
A cooling cell 20 is interposed.

Outside the current collecting electrodes 14 and 16, insulating plates 19a and 19b are interposed to form end plates 21a and 21b.
21b is arranged. End plates 21a, 21b
Are fastened by tie rods or the like via a backup plate (not shown), and the power generation cell 12, the current collecting electrodes 14, 16 and the first and second cooling cells 18, 20
Are integrally clamped and held in the direction of arrow A. A load 22 such as a motor is connected to the current collecting electrodes 14 and 16 (see FIG. 1).

As shown in FIGS. 2 and 3, the power generation cell 12 is made of silicon carbide porous or basic polymer, for example,
A joined body (electrolyte layer / electrode joined body) 30 in which a cathode-side electrode 26 and an anode-side electrode 28 are arranged with an electrolyte layer 24 made of polybenzimidazole impregnated with phosphoric acid and an electrolyte part 24 made of a frame-shaped member interposed therebetween Having. The cathode-side electrode 26 and the anode-side electrode 28 are, for example, a gas diffusion layer made of porous carbon paper or the like, which is a porous layer, and a porous carbon particle having a platinum-based catalyst supported on the surface. And an electrode catalyst layer uniformly coated on the electrode portion.
4.

On both sides of the joined body 30, first and second separators 32 and 34 formed of a conductive material, for example, a dense carbon material or metal, are arranged.
And the first and second separators 32 and 34 constitute the power generation cell 12.

The power generation cell 12 has a fuel gas supply communication passage 36a for passing a fuel gas such as a hydrogen-containing gas and a oxidizing gas as an oxygen-containing gas at the lower portions on both ends in the lateral direction (direction of arrow B). Oxidant gas supply communication passage 38 for
a. On the upper side of both ends of the power generation cell 12 in the lateral direction,
Fuel gas discharge communication passage 36b for passing fuel gas
And an oxidizing gas discharge communication passage 38b for allowing the oxidizing gas to pass therethrough are provided at diagonal positions with respect to the fuel gas supply communication passage 36a and the oxidizing gas supply communication passage 38a.

Notched portions 40a and 40b are provided at the center of both ends in the lateral direction of the power generation cell 12, and a refrigerant supply line 46 and a refrigerant discharge line 48 are arranged in the notched portions 40a and 40b. . A cooling liquid supply passage 46a is formed in the coolant supply line 46, while a coolant discharge line 48 is formed.
A cooling liquid discharge communication passage 48a is formed therein.

The cathode electrode 26 of the first separator 32
The oxidizing gas supply passage 38a and the oxidizing gas discharge communicating passage 38b are formed at both sides thereof with an oxidizing gas passage 50 for supplying the oxidizing gas to the cathode electrode 26 at both ends thereof. (See FIGS. 2 and 3). A fuel gas supply communication passage 36a and a fuel gas discharge communication passage 36b are provided on the surface of the second separator 34 facing the anode 28.
A fuel gas flow path 51 is provided at both ends thereof for supplying a fuel gas to the anode 28. The oxidizing gas flow path 50 and the fuel gas flow path 51 adopt a flow path structure that guides the oxidizing gas and the fuel gas vertically upward while meandering in the horizontal direction (the direction of arrow B).

The surfaces of the first and second separators 32 and 34 facing the cathode side electrode 26 and the anode side electrode 28 are provided with a fuel gas supply passage 36a, an oxidant gas supply passage 38a, and a fuel gas discharge passage 36b. In order to hermetically seal the oxidizing gas discharge communication passage 38b, the oxidizing gas flow passage 50, and the fuel gas flow passage 51, a sealing member 53 is provided.
For example, it is provided by baking or the like.

As shown in FIG. 1, the first cooling cell 18
1 between the current collecting electrodes 14 and 16 in the fuel cell stack 10.
Every 0 cells, that is, 10 cells between the first cooling cells 18
The power generation cells 12 are arranged and stacked. This first
As shown in FIGS. 2 and 3, the first and second separators 32 and 34 disposed on both sides of the cooling cell 18 each have a single-sided gas passage having a flat surface on the first cooling cell 18 side. The separator structure is set. The same applies to the second cooling cell 20 described later. Other first
The oxidizing gas passage 50 and the fuel gas passage 51 are formed on both surfaces of the second separators 32 and 34.

As shown in FIGS. 3 and 4, the first cooling cell 18 includes a cooling liquid flow path plate 52, a lid plate 56 which is superposed on the flow path plate 52 to form a cooling liquid passage 54, The cooling liquid supplied to the cooling liquid passage 54 is supplied to the power generation cell 12 and the current collecting electrodes 14 and 16.
Sheet (insulation mechanism) 5 for electrical insulation from
8a, 58b and a conductive plate (conductive mechanism) for electrically connecting the power generation cells 12 (or the power generation cell 12 and the current collecting electrodes 14, 16) to each other with the first cooling cell 18 interposed therebetween. 60a and 60b. The channel plate 52 and the lid plate 56 are formed of, for example, a light alloy such as an aluminum alloy or a titanium alloy, or a dense carbon material.

The flow path plate 52 projects from one surface side toward the center of both ends in the width direction (the direction of arrow B) and has a cylindrical connection portion 6.
2a and 62b are provided, and the connection portions 62a and 62b are provided.
Is connected to a refrigerant supply line 46 and a refrigerant discharge line 48. On the other surface side of the flow path plate 52, a cooling liquid passage 54 is formed.

As shown in FIGS. 4 and 5, the cooling liquid passage 54 is provided in the height direction of the flow path plate 52 (in the direction of arrow C).
Are divided into approximately three equal parts into a central passage 54a at the center in the plane and an upper passage 54b and a lower passage 54c at the inner end of the upper and lower surfaces. The central passage 54a corresponds to the central portion of the power generation surface, and the flow passage structure is set so as to supply a larger amount of cooling liquid than the upper passage 54b and the lower passage 54c corresponding to the upper and lower portions of the power generation surface.

In the cooling liquid passage 54, the number of flow rates per unit width in the vertical direction (direction of arrow C) is adjusted. Specifically, the central passage 54a has straight lines parallel to each other in the direction of arrow B. The four passage grooves 64a extending in the shape of a circle are formed, and the upper passage 54b and the lower passage 54c have
Five flow channel grooves 64b and 64c are formed, each extending linearly in parallel with the direction of arrow B.

In this configuration, the central passage 54a is provided with approximately 14/2 of the total cooling liquid flow supplied to the cooling liquid passage 54.
4, a flow rate of approximately 5/24 is introduced into the upper passage 54b and the lower passage 54c, respectively. The number of the flow grooves 64a, 64b and 64c is set in accordance with the flow rate of the cooling liquid to be introduced into each of them, and in the first embodiment, 1/1 of the total cooling liquid flow rate in the central passage 54a. It is desirable to set so that a flow rate of 3 to 2/3 is supplied.

Guides 66a, 66b for uniformly and stably flowing the cooling liquid are provided between both ends of the flow grooves 64a, 64b, 64c and the connecting portions 62a, 62b.
Is provided.

As shown in FIG. 4, the lid plate 56 has cylindrical connecting portions 68a and 68b protruding outward on a surface opposite to the surface facing the flow path plate 52. The connecting portions 68a and 68b are connected to the connecting portions 6 of the flow path plate 52.
It is provided at the same position as 2a, 62b, and is connected to the refrigerant supply line 46 and the refrigerant discharge line 48.

The conductive plates 60a and 60b are arranged to cover the flow path plate 52 and the lid plate 56, while the insulating sheets 58a and 58b are
0a and 60b are provided on the surface side in contact with the flow path plate 52 and the lid plate 56. Conductive plate 6
Reference numerals 0a and 60b are made of a metal plate having excellent electric conductivity such as a copper alloy.

The insulating sheets 58a and 58b are formed of an insulating material, for example, polytetrafluoroethylene (PTFE), and are adhered over the entire surfaces of the conductive plates 60a and 60b with an adhesive or the like. Note that an insulating material such as silicon grease may be applied to the conductive plates 60a and 60b instead of the insulating sheets 58a and 58b.

The upper ends of the conductive plates 60a and 60b are bent in directions approaching each other to form a joint 7
0a and 70b are provided, and
Holes 72a and 72b are formed in the holes a and 70b. A fixing plate 74 is arranged so as to cover the mating portions 70a and 70b. A screw 76 is inserted from the fixing plate 74 into the holes 72a and 72b, and a nut 78 is screwed into the screw 76 to thereby form the conductive plate 60a. , 60b hold the flow path plate 52 and the lid plate 56.

As shown in FIG. 1, the second cooling cell 20
In the fuel cell stack 10, it is arranged between the first cooling cells 18 adjacent to each other, and every five cells between the current collecting electrodes 14 and 16 and the first cooling cells 18. Specifically, at the center between the first cooling cells 18 and between the current collecting electrodes 14 and 16 and the first cooling cells 18, five power generation cells 12 are arranged on both sides, respectively. 20 are stacked.

As shown in FIGS. 3 and 6, the second cooling cell 20 is provided with a flow path plate 8 for cooling gas (for example, air).
0, and a lid plate 84 that is superimposed on the flow path plate 80 to form a cooling air passage 82. The channel plate 80 and the lid plate 84 are formed of a light alloy material such as an aluminum alloy or a titanium alloy that is lightweight and has good thermal and electrical conductivity.

The cooling air passage 82 is provided on one surface 80a of the flow path plate 80, and has a plurality of flow grooves 86 extending linearly in the vertical direction (the direction of arrow C).
An air inlet 90 provided with a guide 88 communicates with the lower end of the flow channel 86. The cooling air passage 82 extends in the lateral direction of the cathode electrode 26 and the anode electrode 28 (arrow B).
Direction) is set in the range of 60% to 70% of the width dimension.

The lid plate 84 is formed with a chamber 92 communicating with the air introduction section 90, and this chamber 92 is formed with an air introduction port 94.
Communicate with The air inlet 94 is connected to a pipe 96 that has been subjected to electrical insulation processing. The channel plate 80 and the lid plate 84 are fixed to each other by a plurality of screws 98.

As shown in FIG. 2, the end plate 21a
A fuel gas inlet 100a communicating with the fuel gas supply communication passage 36a, a fuel gas outlet 100b communicating with the fuel gas discharge communication passage 36b, and an oxidizing gas inlet 102a communicating with the oxidizing gas supply communication passage 38a; An oxidizing gas outlet 102b communicating with the oxidizing gas discharge communication passage 38b is formed.

FIG. 7 is a schematic diagram illustrating a fuel cell system 110 incorporating the fuel cell stack 10 according to the first embodiment.

The fuel cell system 110 includes a fuel gas supply section 112 for supplying a fuel gas to the fuel cell stack 10.
An oxidizing gas supply unit 114 for supplying an oxidizing gas to the fuel cell stack 10;
A cooling liquid supply unit 116 for supplying a cooling liquid (liquid cooling medium) to the fuel cell stack 10, and a cooling air supply unit 118 for supplying cooling air to the fuel cell stack 10.

The fuel gas supply unit 112 includes a high-pressure hydrogen storage source 120, and a first pressure reducing valve is connected to a fuel gas pipe 122 connected from the high-pressure hydrogen storage source 120 to the fuel gas supply communication passage 36 a in the fuel cell stack 10. 124 and a fuel gas flow controller 126 are provided.

The oxidizing gas supply unit 114 includes a first compressor 128, and a second decompressed gas is supplied to the oxidizing gas pipe 130 from the first compressor 128 to the oxidizing gas supply communication passage 38 a in the fuel cell stack 10. A valve 131 and an oxidizing gas flow controller 132 are provided.

The cooling liquid supply section 116 includes a cooling liquid pipe 134 connecting the cooling liquid supply communication path 46a and the cooling liquid discharge communication path 48a in the fuel cell stack 10. The cooling liquid pipe 134 has a circulation pump. 136 and a relatively small heat exchanger 138 are provided.

The cooling air supply section 118 includes a second compressor 140, which is connected to a cooling air pipe 142 connected to the second cooling cell 20 of the fuel cell stack 10. This cooling air pipe 1
42, a third pressure reducing valve 144 and a cooling air flow controller 14
6 are provided.

The fuel cell stack 1 configured as described above
The operation of 0 will be described below in relation to the fuel cell system 110.

First, in the fuel cell system 110, the fuel gas supply unit 1 is operated in accordance with the required current of the load 22 such as a motor.
12 and the oxidizing gas supply unit 114 are controlled.
In the fuel gas supply unit 112, a high-pressure hydrogen storage source 120 is supplied through a first pressure reducing valve 124 and a fuel gas flow controller 126.
Supplies a predetermined amount of fuel gas (hydrogen gas or hydrogen-containing gas) to the fuel cell stack 10.

On the other hand, the oxidizing gas supply section 114
The flow rate of the oxygen-containing gas (hereinafter, also referred to as air), which is an oxidizing gas introduced through the compressor 128, is controlled through the second pressure reducing valve 131 and the oxidizing gas flow controller 132. For this reason, the fuel cell stack 10 includes
A predetermined amount of oxygen-containing gas is supplied.

As shown in FIG. 2, the end plate 21a
The fuel gas supplied to the fuel gas inlet 100a is supplied to the fuel gas flow path 51 formed in the second separator 34 via the fuel gas supply communication passage 36a. Therefore, the hydrogen-containing gas in the fuel gas is supplied to the anode 28 of the power generation cell 12, and the unused fuel gas is discharged to the fuel gas discharge communication passage 36b.

The air supplied to the oxidizing gas inlet 102a of the end plate 21a is introduced into the oxidizing gas flow path 50 formed in the first separator 32 through the oxidizing gas supply communication passage 38a. . Therefore, while the oxygen-containing gas in the air is supplied to the cathode electrode 26, the unused air is discharged to the oxidizing gas discharge communication passage 38b. As a result, power is generated in the power generation cell 12, and power is supplied to the load 22 such as a motor (see FIG. 1).

As described above, when power is generated in the fuel cell stack 10, heat is generated with this power generation, and the temperature of each power generation cell 12 rises. The optimum operating temperature of the power generation cell 12 is, for example, 160 ° C. when the electrolyte part 24 in which the polybenzimidazole film is impregnated with phosphoric acid is used.
It is necessary not to exceed. Therefore, in the fuel cell system 110, as shown in FIG.
The pump 136 constituting 16 is driven.

Under the action of the pump 136, the cooling liquid supplied to the cooling liquid supply passage 46 a of the fuel cell stack 10 is formed between the flow path plate 52 and the lid plate 56 constituting the first cooling cell 18. Is introduced into the cooling liquid passage 54. As shown in FIG. 4, in the flow path plate 52, the flow path grooves 64a, 64b and 64
c, the cooling liquid is introduced into the flow channel 6.
After cooling the power generation surface of the power generation cell 12 through 4a, 64b and 64c, it is discharged to the cooling liquid discharge communication passage 48a.

The cooling liquid drawn from the cooling liquid discharge communication passage 48a to the cooling liquid pipe 134 takes heat from each of the power generation cells 12 and has a relatively high temperature, and is introduced into the heat exchanger 138 (FIG. 7). reference). In the heat exchanger 138, heat is released from the cooling liquid, and the cooling liquid whose temperature has decreased is circulated again to the first cooling cell 18.

In this case, in the first cooling cell 18, as shown in FIGS. 4 and 5, the cooling liquid passage 54 provided in the flow path plate 52 has a central passage 54 a vertically divided into approximately three equal parts, A passage 54b and a lower passage 54c are provided, and respective passage grooves 64a, 64b and 64
In c, the number of flow paths per unit width in the vertical direction is adjusted.

More specifically, the number of the central flow grooves 64a is set to 14, while the number of the upper and lower flow grooves 64b, 64c is set to 5. Thereby, the central passage 54
a, a flow rate of about 14/24 of the total cooling liquid flow rate supplied to the cooling liquid passage 54 is introduced, while the upper passage 54
A flow rate of approximately 5/24 is introduced into b and the lower passage 54c, respectively.

For this reason, a larger amount of cooling liquid is supplied to the central passage 54a than the upper passage 54b and the lower passage 54c, and the central portion, which tends to become relatively high in temperature, in the power generation surface of each power generation cell 12 is forced. In addition to the cooling, the cooling efficiency of the outer peripheral portion, which tends to be relatively low, decreases. Therefore, the temperature distribution in the in-plane direction of the power generation cell 12 can be effectively reduced, and the maximum temperature in this in-plane direction can be reduced.

Thus, in the first embodiment, the temperature difference between the power generation cells 12 in the stacking direction is reduced, the power generation performance of each power generation cell 12 approaches the maximum performance, and the output of the fuel cell stack 10 as a whole is reduced. The effect of being able to improve satisfactorily is obtained.

Further, in the first embodiment, the central passage 5
A flow rate of 1/3 to 2/3 of the total flow rate of the cooling liquid supplied to the cooling liquid passage 54 is supplied to 4a. Therefore, the in-plane temperature of the power generation cells 12 can be made as uniform as possible, and the power generation performance of each power generation cell 12 can be significantly improved.

When a flow rate equal to or less than 1/3 of the total cooling liquid flow rate is supplied to the central passage 54a, it is difficult to make the in-plane temperature of the power generation cell 12 uniform. On the other hand, when a flow rate of 全 or more of the total cooling liquid flow rate is supplied to the central passage 54a, the flow rates of the upper passage 54b and the lower passage 54c are insufficient, and it is difficult to have a desired cooling function. .

By the way, in the fuel cell stack 10, when a high load is required and a high output state is reached, the heat generation of each power generation cell 12 increases. At this time, the liquid cooling medium and the small heat exchanger 138, that is, the first cooling cell 18
Before only the maximum temperature of all the power generation cells 12 cannot be maintained below the optimum operation temperature, the cooling air supply unit 118 is driven to supply the cooling air to the second cooling cells 20 (see FIG. 7).

In the cooling air supply section 118, after the flow rate of the cooling air introduced through the second compressor 140 is adjusted through the third pressure reducing valve 144 and the cooling air flow controller 146, Pipe 9 constituting cell 20
6 to the air inlet 94.

As shown in FIGS. 3 and 6, the cooling air flows from the air inlet 94 through the chamber 92 to the air inlet 90.
Will be introduced. The air introduction section 90 is provided with a cooling air passage 82 via a guide 88, and the cooling air is uniformly and stably introduced into the plurality of flow grooves 86 via the guide 88. And flows vertically upward. Thereby, the power generation cell 12 near the second cooling cell 20 is cooled.

Therefore, while maintaining the power generation cell 12 near the first cooling cell 18 at a temperature close to the optimum operating temperature,
The power generation cell 12 in the vicinity of the second cooling cell 20 can be cooled to the optimum operation temperature. Thereby, the temperature of each power generation cell 12 is adjusted to be near the optimum operation temperature, and the temperature difference between the power generation cells 12 along the stacking direction is reduced, so that each power generation performance of each power generation cell 12 is effective. The effect that it can be improved is obtained.

In addition, at the time of high output, the second cooling cell 20 is used together with the first and third cooling cells 18 to cool only the power generation cells 12 that need to be cooled. For this reason, it is not necessary to use a large heat exchanger for cooling, and a relatively small heat exchanger 138 can cope well.

Further, since the second cooling cell 20 uses cooling air, it does not use a conductive cooling liquid as in the first cooling cell 18. Therefore, there is no need to insulate between the cooling air and the power generation cell 12, and there is an advantage that the configuration of the second cooling cell 20 is effectively simplified.

In the first embodiment, the first and second cooling cells 18 and 20 are equally distributed in the stacking direction, that is,
The fuel cell stacks 10 are arranged at equal intervals, but may be appropriately adjusted so that the temperature distribution in the stacking direction of the fuel cell stack 10 is reduced.
The arrangement position can be adjusted.

FIG. 8 is an explanatory side view showing a schematic configuration of a fuel cell stack 160 according to the second embodiment of the present invention. The fuel cell stack 10 according to the first embodiment
The same components as those described above are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In the fuel cell stack 160, the second cooling cells 20 are not used, and a predetermined number of the first cooling cells 18 are used.
Each power generation cell 12 is configured to be cooled only through the power generation cell 12. Thereby, under the cooling action of the first cooling cell 18, the temperature difference of each power generation cell 12 can be reduced along the stacking direction and along the power generation surface direction. Accordingly, the power generation performance of each power generation cell 12 is effectively maintained, and the size of the entire fuel cell stack 160 is easily reduced.

[0073]

In the fuel cell stack according to the present invention, the cooling cell is a cooling medium flow path for supplying a larger amount of cooling medium to the center in the plane than the in-plane end in the plane corresponding to the power generation surface. In the in-plane direction, the in-plane central portion where the temperature tends to be relatively high is forcibly cooled, while the cooling efficiency of the in-plane outer peripheral portion where the temperature tends to be relatively low decreases.

Accordingly, the temperature distribution in the in-plane direction of the power generation cell can be effectively reduced, and the maximum temperature in the in-plane direction can be reduced. As a result, the temperature difference between the power generation cells in the stacking direction is reduced, and the power generation performance of each power generation cell approaches the maximum performance, so that the output of the fuel cell stack can be improved satisfactorily.

[Brief description of the drawings]

FIG. 1 is an explanatory side view showing a schematic configuration of a fuel cell stack according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the fuel cell stack.

FIG. 3 is an enlarged sectional view of a main part of the fuel cell stack.

FIG. 4 is an exploded perspective view of a first cooling cell constituting the fuel cell stack.

FIG. 5 is an explanatory front view of a flow path plate constituting the first cooling cell.

FIG. 6 is an exploded perspective view of a second cooling cell constituting the fuel cell stack.

FIG. 7 is a schematic configuration diagram of a fuel cell system incorporating the fuel cell stack.

FIG. 8 is an explanatory side view showing a schematic configuration of a fuel cell stack according to a second embodiment of the present invention.

[Explanation of symbols]

10, 160 ... fuel cell stack 12 ... power generation cells 14, 16 ... current collecting electrodes 18, 20 ... cooling cells 19a, 19b, 58a, 58b ... insulating sheets 21a, 21b ... end plate 24 ... electrolyte part 26 ... cathode side electrode 28 Anode-side electrode 30 Joints 32 and 34 Separator 46 Refrigerant supply line 48 Refrigerant discharge line 50 Oxidant gas flow path 51 Fuel gas flow paths 52 and 80 Flow path plate 54 Cooling liquid Passage 54a Central passage 54b Upper passage 54c Lower passage 56, 84 Cover plates 60a, 60b Conductive plates 64a to 64c,
86 ... flow path groove 82 ... cooling air passage 90 ... air introduction part 94 ... air introduction port 110 ... fuel cell system 112 ... fuel gas supply part 114 ... oxidant gas supply part 116 ... cooling liquid supply part 118 ... cooling air supply part

Claims (3)

[Claims] An assembly comprising an electrolyte sandwiched between an anode electrode and a cathode electrode, wherein the assembly is sandwiched between separators and fuel gas is supplied to the anode electrode, A power generation cell in which an oxidant gas is supplied to a cathode side electrode; a pair of current collection electrodes electrically connected integrally to a predetermined number of the power generation cells; and an interposition between the current collection electrodes And a cooling cell for supplying a cooling medium for cooling the power generation cell along a power generation surface; and an insulating mechanism for electrically insulating the cooling medium from the power generation cell and the current collecting electrode. And a conductive mechanism for electrically connecting the power generation cells or the power generation cell and the current collecting electrode to each other with the cooling cell interposed therebetween. In the plane corresponding to Oite,
A fuel cell stack, wherein a cooling medium flow path for supplying a larger amount of the cooling medium than an in-plane end portion is provided in an in-plane central portion. 2. The fuel cell stack according to claim 1, wherein the cooling medium flow passages are formed in the in-plane central portion and the in-plane end portions provided on both sides of the in-plane central portion. A fuel cell stack, wherein a flow rate of １ ／ to ／ of a total flow rate of the cooling medium supplied to the cooling medium flow path is supplied to the in-plane central portion. . 3. The fuel cell stack according to claim 1, wherein a cooling gas for cooling the power generation cells is supplied, and a predetermined number of the power generation cells are sandwiched between the fuel cells and the cooling cells. A fuel cell stack comprising an auxiliary cooling cell interposed between electrodes for use in fuel cells.