JP2001110439A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve practical use of a fuel cell by making it compact. SOLUTION: Four stacks are combined via a supply/exhaust box 200 for organizing a fuel cell. A water supply opening for supplying cooled water, and a water exhaust opening for exhausting water are short circuited by a cable to eliminate difference in potentials between the two openings. A water exhaust port for exhausting waterdrop is provided near an exhaust outlet of fuel gas of the supply/exhaust box. Each stack is constructed such that end plates provided at both ends of laminated cells are gripped by an upper side tension plate and a lower side tension plate, and the tension plates and the end plates are fixed tightly with bolts, which are inserted vertically for avoiding interference between the adjacent stacks and the supply/exhaust box. An insulating body is provided in one body with a surface of the tension plate contacting the cell. Thus, the entire organized fuel cell stored in an outer case, where the outer case is sealed tightly for preventing foreign obstacles from infiltration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell having a hydrogen electrode and an oxygen electrode with an electrolyte layer permeable to hydrogen ions interposed therebetween, and to a technique for reducing the size of a stack formed by stacking cells.

[0002]

2. Description of the Related Art Conventionally, a hydrogen electrode and an oxygen electrode are provided with an electrolyte layer permeable to hydrogen ions interposed therebetween, and a cathode (hydrogen electrode) and an anode (oxygen electrode) have the following reaction formulas (1) and (2), respectively. There has been proposed a fuel cell that generates an electromotive force by causing a reaction according to the temperature. The electrolyte layer is composed of a cathode (hydrogen electrode) H ² → 2H ⁺ + 2e ⁻ (1) an anode (oxygen electrode) (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)

Various types of fuel cells, such as a phosphoric acid type fuel cell, a molten carbonate type fuel cell, a solid electrolyte type fuel cell, and an alkaline type fuel cell, have been proposed according to the type of the electrolyte layer. In recent years, polymer electrolyte fuel cells using a hydrogen ion conductive polymer membrane as the electrolyte layer have attracted attention because of their high output density and the possibility of miniaturization, and various improvements have been studied. ing.

[0004] The fuel cell has a theoretical electromotive force per unit cell of about 1.23 V in both types.
A desired voltage is obtained by stacking many cells. A unit in which cells are stacked and fixed in a case is called a stack. Generally, in a stack, the stacking accuracy of cells appears as an internal resistance. Therefore, when an extremely large number of cells are stacked, the internal resistance increases and the efficiency of the fuel cell decreases. Further, if an extremely large number of cells are stacked, it becomes difficult to supply the fuel gas evenly to each cell. For these reasons, avoid configuring a fuel cell with a single stack of stacked cells to such an extent that a desired voltage is obtained, construct a fuel cell by dividing it into multiple stacks, and connect them in series. Usually, a desired voltage is obtained. The applicant of the present application has disclosed a technique in a fuel cell using a plurality of stacks in which fuel can be uniformly supplied to each stack and the overall size can be reduced.
The technology described in No. is proposed. This is a structure in which four stacks are connected via a supply / discharge member.

[0005]

However, the stack is
It has been found that, when it is intended to be mounted on various devices such as a vehicle, there are the following various problems in addition to the fuel supply / discharge problem. Conventionally, in the means for solving each of these problems, the miniaturization of the fuel cell has not been sufficiently considered, so that trying to solve each of the problems may cause another problem that the fuel cell becomes large. there were. In this sense,
Regarding the following problems, preferable solutions have not been sufficiently studied.

[0006] The first problem with the stack is due to cooling. The fuel cell is cooled by cooling water. The cooling water flows through a cooling water passage formed in a separator constituting a gas flow passage of the cell. The separator is generally formed of a conductive member. Therefore, the cooling water is charged in accordance with the potential of the electrode by contacting the conductive separator in the process of cooling the cell. Depending on the configuration of the water supply port for supplying the cooling water to the stack and the drainage port for discharging the cooling water from the stack, there may be a potential difference near these. In such a case, there is a possibility that adverse effects such as electrolytic corrosion may be caused between the water supply port and the drain port due to the potential difference. If measures such as covering the water supply port and the drain port with an insulating material in order to avoid such adverse effects are taken, the size of the stack increases accordingly. In particular, in a structure in which a plurality of stacks are connected via a supply / discharge member, the potential difference between the water supply port and the discharge port reaches several hundred volts. A large impact. In addition, if a water inlet and a drain are installed together in a location where there is no potential difference, restrictions on the locations of the water inlet and the drain are increased, which reduces the degree of freedom in designing the cooling water channel and reduces the size of the device. It is a factor that hinders the conversion.

[0007] The second problem with the stack is due to the drainage of water generated during the reaction. As shown in equations (1) and (2) above, the fuel cell reacts with water (H
₂ O) is produced. The water generated in this cell is carried by the gas flow through a manifold that supplies gas to the stack to a gas outlet. In a polymer electrolyte membrane fuel cell, water used for humidifying the electrolyte membrane is also carried to the gas outlet through the same route. At this time, when the amount of water carried to the gas outlet increases, a phenomenon called flooding occurs, and the operation of the fuel cell may become unstable.
In other words, water droplets condensed inside the gas discharge port reduce the cross-sectional area of the gas flow path, thereby impeding the flow of gas, and thus obstructing the supply of gas to each cell. Make it stable. To avoid such an adverse effect, a structure in which a drain port is provided in a stack is disclosed in Japanese Patent Application Laid-Open No. H11-204126. However, in this structure, a drain valve and a discharge port are provided outside the stack, and there is a problem that the structure of the stack, and eventually the structure of the entire fuel cell, becomes extremely large. In a fuel cell including a plurality of stacks, it is necessary to provide a drainage mechanism for each stack, which further increases the size of the fuel cell.

[0008] The third problem with the stack is a problem due to the insulating properties of the cells. The stack is configured by fixing the stacked cells so as not to be separated in the stacking direction. The external structure that serves to fix the cells is referred to herein as a stack case. Since the cell is a collection of electrodes, it is necessary to insulate the cell from the stack case when forming the stack in this way.
Conventionally, the insulation between the cell and the stack case has been ensured by inserting an insulator such as silicon rubber between the cell and the stack case. However, in order to insulate both with such a structure, a step of inserting an insulator is required in the manufacturing process of the stack, which may reduce productivity.
As described above, the process of forming a stack by stacking cells is a process that requires precision related to the internal resistance. There was also. In general, insulators such as silicon rubber have relatively low accuracy with respect to thickness.
In order to form a stack without applying an unnecessary load to the cell, it is necessary to manufacture the stack case in a large size in consideration of variations in the thickness of the insulator. Furthermore, in order to maintain the shape of the insulator itself, a certain thickness is required, so that the insulator becomes unnecessarily large,
This caused the stack case to become larger.

The applicant of the present application discloses one technique for avoiding such an increase in size as Japanese Patent Application Laid-Open No. 8-162143. This technique is a technique of coating and coating rubber on four sides of a stack. However, when the stack is insulated by such a method, an extra step of applying rubber is required, and another problem that repair is difficult when breakage or the like occurs in the stack once covered with rubber. Invites challenges. From this point of view, the stack can be reliably insulated without impairing the productivity of the stack, and
There has been a demand for a technology capable of avoiding an increase in the size of the stack case.

[0010] The fourth problem with the stack is a problem caused by securing waterproofness, dustproofness, and rigidity of the stack. As described above, the stack has a plurality of cells fixed by the stack case. However, in view of the necessity of attaching a terminal for monitoring the voltage of the cell and the workability in attaching the terminal, the stack case is often not completely sealed. Therefore, when the stack having such a structure is used by being mounted on various devices such as a vehicle, there is a possibility that water, dust, and the like may enter the gap between the cells depending on the use environment. In addition, the operation of these devices usually involves vibration, and when the vibration and a load resulting from the vibration act on the stack, a gap may be generated between cells due to distortion generated in the stack. Due to these factors, the stack may cause a decrease in power generation efficiency due to an increase in internal resistance, a power generation failure, or the like.

In order to solve such a problem, it is possible to take a method of completely sealing the outer periphery of the stack case and increasing the rigidity of the stack case to such an extent that the stack case is not deformed by vibration or the like. However, providing a step of sealing the outer periphery of the stack case impairs the productivity of the stack. Further, in order to sufficiently increase the rigidity of the stack case, it is necessary to increase the thickness of the stack case, which leads to an increase in the weight and size of the stack. Particularly, in a fuel cell using a plurality of stacks, the effect was great.

A fifth problem of the stack is a problem caused by a mechanism for applying an elastic force to the stacked cells. When a cell is stacked to form a stack, it is desirable to make the cells as close as possible to reduce the internal resistance. On the other hand, during power generation, heat is generated by a chemical reaction and the cells thermally expand, so if the stacked cells are completely fixed, deformation due to thermal stress may occur, such as power generation failure and shortened life. May cause adverse effects. A technique for solving such a problem is disclosed in Japanese Unexamined Patent Publication No.
33132. This is a technology that attaches an end plate to one end where cells are stacked via a disc spring, and urges the force to make cells adhere to each other while absorbing deformation caused by thermal expansion and the like by the elastic force of the disc spring. Is what you do. The applicant of the present application also discloses a technique for solving the above problem in Japanese Patent Laid-Open No. Hei 7-335243. This is a technology in which an end plate is attached to one end of a stacked cell via an elastic member, and a space between the end plate and one end of the cell is used as a pressure chamber into which a fluid can be injected. Utilizing the elastic force of the member and the pressure of the fluid, a force for bringing the cells into close contact with each other is urged while absorbing deformation caused by thermal expansion and the like.

However, in these techniques, since the end plate is fixed by bolts penetrating in the stacking direction, there is a problem that the stack becomes large due to the bolt space. In particular, the stack was longer in the stacking direction. In a fuel cell, it is necessary to stack a large number of cells in order to secure a voltage, and the dimension in the stacking direction tends to be necessarily increased. On the other hand, from the viewpoint of securing space when mounting the fuel cell on various devices such as vehicles, it is often preferable to avoid a shape in which the size in one direction is extremely large. From such a viewpoint, it is desirable to suppress the size of the cells in the stacking direction as much as possible, and the increase in size due to the above-mentioned bolt space impairs the efficiency of mounting the stack on the device. In particular, the effect on a fuel cell using a plurality of stacks is significant. Therefore, there has been a demand for a technique that can reduce the size of the stack, particularly the size in the stacking direction, while providing an appropriate elastic force in the stacking direction of the cells.

As described above, the conventional fuel cell has various practical problems, resulting in a large problem of increasing the size of the stack. The present invention has been made in view of these problems, and has as its object to solve at least a part of the above-described five problems, including a viewpoint of avoiding an increase in the size of a stack.

[0015]

Means for Solving the Problems and Their Functions / Effects To solve at least one of the problems of downsizing the fuel cell and at least part of the various problems described above,
The present invention employs the following configuration. The first fuel cell according to the present invention is a fuel cell including a stacked battery in which unit cells are stacked, and a mechanism for cooling by passing a conductive refrigerant through the stacked battery. A supply port for supplying the battery, and a discharge port for discharging the refrigerant from the stacked battery, a cooling mechanism provided at a portion having a different potential,
The gist of the invention relates to a refrigerant path through which the refrigerant flows, and further comprises a short-circuit means for electrically short-circuiting the refrigerant path upstream of the supply port and the refrigerant path downstream of the discharge port.

According to the first fuel cell, the potential difference between the cooling water generated at the supply port and the discharge port can be eliminated by the short-circuit means, so that adverse effects such as electrolytic corrosion can be easily avoided. The means for electrically short-circuiting the refrigerant path having a potential difference can be realized by connecting both with a conductive member, and thus does not cause adverse effects such as an increase in the size of the fuel cell and an increase in manufacturing cost. This also makes it possible to avoid an increase in the size of the device due to the provision of insulating members at the supply port and the discharge port. Further, since there is no restriction such as providing both at a portion where there is no potential difference, the degree of freedom in design is increased and the size of the device can be further reduced.

Note that the supply port and the discharge port mean holes provided in the stacked battery for supplying and discharging the refrigerant, and include “a refrigerant path upstream of the supply port” and “a refrigerant path downstream of the discharge port. The “refrigerant path” means a refrigerant path communicated with the stacked battery. Therefore, the short-circuit means of the present invention is provided outside the laminated battery, not inside. Thus, since the short-circuit means can be mounted after the stacked battery is formed, there is an advantage that the short-circuit means can be provided without impairing the productivity of the stacked battery. There is also an advantage that it is easy to cope with a failure such as a disconnection.

The short-circuit means may be applied to a single stacked battery. However, when the fuel cell includes a plurality of the stacked batteries, the refrigerant path is connected to each of the stacked batteries. At least a portion of the refrigerant passage upstream of the supply port,
And at least a part of the refrigerant path downstream of the outlet of each of the stacked batteries is configured as a common refrigerant path, and the short-circuit means is provided at a location configured as a common refrigerant path for the plurality of stacked batteries. Is desirable.

According to this configuration, since the short-circuit means is provided in the common refrigerant passage, the potential difference of the refrigerant can be eliminated without providing the short-circuit means in each of the stacked batteries. Therefore,
The process and cost for providing the short-circuit means can be reduced. Since the refrigerant that has passed through a plurality of stacked batteries may have a very large potential difference, the utility of the present invention is very high in that the potential difference can be easily eliminated. As an example of a fuel cell including a plurality of stacked batteries, by performing the function of distributing the supplied fuel gas to each of the stacked batteries and the function of aggregating the exhaust gas from each of the stacked batteries, the outside and each of the stacked batteries and And a structure provided with a supply / discharge member for realizing supply / discharge of fuel during the period. In this case, the above-described common refrigerant path is formed inside the supply / discharge member. In such a case, for example, the configuration of the present invention can be realized by short-circuiting the vicinity of the supply port and the discharge port for supplying and discharging the cooling water to and from the supply and discharge member.

A second fuel cell according to the present invention is a fuel cell including a plurality of stacked cells in which unit cells are stacked, and has a function of distributing the supplied fuel gas to each of the stacked cells. And a supply / discharge member that realizes supply / discharge of fuel between the outside and each of the stacked batteries by performing a function of consolidating exhaust gas from each of the stacked batteries, and the supply / discharge member has an internal structure, The gist of the present invention is that the structure includes an integrated gas flow path through which the integrated exhaust gas flows, and a drainage mechanism that branches off from the integrated gas flow path and discharges water droplets in the gas flow path.

According to the second fuel cell, the drainage mechanism provided in the supply / discharge member can appropriately discharge the water droplets in the gas flow path, so that flooding can be avoided. In addition, since the drainage mechanism is provided in the supply / discharge member, unlike the related art described in Japanese Patent Application Laid-Open No. H11-204126, there is no need to provide an external drain valve or the like, and an increase in the size of the apparatus can be avoided. In particular, since the drainage mechanism is provided in the supply / discharge member, it is possible to avoid providing a drainage mechanism individually for each of the stacked batteries, and the device can be downsized.

The drainage mechanism can be composed of a water storage mechanism that branches off from the gas flow path and temporarily stores water drops, and a drainage pipe that discharges the stored water. The drain pipe may be configured to discharge water by gravity, or may be configured to more positively discharge water by utilizing the pressure of the gas flowing in the gas flow path. In order to supply the fuel gas uniformly to the unit cells without interruption, the gas is usually supplied at a relatively high pressure, and although the pressure loss occurs in the unit cells, the discharged gas is sufficiently higher than the atmospheric pressure. It is normal to have pressure. Therefore, a water storage mechanism in which the pressure of the exhaust gas acts on the water surface, for example, a water storage mechanism provided in a portion where the gas flow path is bent and the pressure is locally increased, or an acute angle with respect to the flow direction of the exhaust gas By using a water storage mechanism or the like provided via a branch that is connected to the outside, water can be positively discharged using this pressure. When the drainage is performed by using the pressure, the degree of freedom with respect to the position of the drainage pipe is increased as compared with the case where the drainage is performed by gravity, so that the size of the apparatus can be further reduced.

A third fuel cell according to the present invention is a fuel cell including a stacked cell in which unit cells are stacked, wherein the stacked cell includes a fixing member for fixing the stacked unit cells, and The gist of the member is that an insulating layer is integrally provided on a surface in contact with the unit cell.

According to the third fuel cell, the step of inserting an insulating material between the unit cell and the fixing member can be omitted in the process of manufacturing the stacked battery, and the productivity can be improved. it can. In particular, since stacking of unit batteries is a precision operation that greatly affects the performance of the stacked battery, simplification in such a process leads to significant improvement in productivity. As a method of integrally providing the insulating layer, various methods such as a method of bonding an insulating member to one surface of a fixing member and a method of applying an insulating material to one surface of the fixing member can be applied.
By forming them integrally by these methods, the thickness of the insulating layer itself can be reduced as compared with the case where the insulating layer is prepared separately. In addition, a dimensional error in thickness can be suppressed. Furthermore, if the insulating layer is prepared separately, even if the position of the insulating layer is shifted,
It is necessary to provide a sufficient gap so that the unit battery and the fixing member do not come into contact with each other. However, when the insulating layer is integrated with the fixing member, such consideration is not required, and the unit battery and the fixing member are unnecessary. Can be reduced. The third fuel cell in which the insulating layer is integrated with the fixing member can reduce the size of the device by these actions.

A fourth fuel cell according to the present invention is a fuel cell including a stacked cell in which unit cells are stacked. The fuel cell includes a plurality of the stacked cells, the plurality of the stacked cells collectively accommodated, and an external And a container having a sealed structure so as to prevent intrusion of foreign matter. Examples of the foreign matter include dust and water.

By providing such a container, it is not necessary for each laminated battery to completely deal with foreign matter. Therefore, the structure of the stacked battery can be simplified, and the size of the stacked battery can be reduced. In addition, productivity can be improved and manufacturing cost can be reduced. Further, when it is necessary to monitor the electric potential of the unit cell, by providing the above-described container, the stacked cell can be configured in a state in which the unit cell can be viewed, so that the utility is high.

The fourth fuel cell also has an advantage in terms of securing rigidity. When a fuel cell is mounted on a vehicle or the like, vibration and various external forces act on the fuel cell. In order to stably generate power, it is necessary to secure a rigidity of the fuel cell such that the fuel cell does not deform due to vibration or external force. Here, the deformation is mainly a bending deformation and a torsional deformation, and the rigidity thereof can be determined by using the second moment of area and the second moment of area as indices. It is known that these coefficients increase as the distance from the neutral axis of bending deformation and the rotation axis of torsional deformation increases. Since the container of the fourth fuel cell accommodates the stacked batteries collectively, the second moment of area and the second moment of area are clearly larger than those of the stacked battery. Therefore, the fourth fuel cell can ensure sufficient rigidity while suppressing the thickness of the material. If the container has sufficient rigidity, it is not necessary for the laminated battery to have such high rigidity, so that the size can be reduced. Also,
Since the thickness of the container can be suppressed, an increase in the weight of the entire fuel cell can also be suppressed.

In the fourth fuel cell, a gas generated in the container is provided separately from a mechanism for supplying and discharging a fuel gas, an oxidizing gas and cooling water to and from the stacked battery in the container. Alternatively, a device for discharging the liquid to the outside of the container may be provided.

Since hydrogen used as a fuel gas is a very fine molecule, it sometimes leaks out of various junctions of the unit cell during operation. Further, water generated by the reaction of the fuel cell may leak out of the stacked cell. Since the fourth fuel cell seals the container, gases and liquids thus discharged may accumulate in the container. According to the above configuration, the gas and the liquid can be appropriately discharged from the container by the discharge mechanism. Note that the discharge mechanism may have a simple configuration in which a discharge pipe is mounted, but it is preferable to provide a valve body or the like at the mounting portion in order to prevent foreign matter from entering from the outside.

A fifth fuel cell according to the present invention is a fuel cell including a stacked cell in which unit cells are stacked, wherein the stacked cell has an elastic member that applies an elastic force to the unit cell in a stacking direction; A pair of end plates arranged in parallel with the unit cells at both ends of the stacked unit cells and having rigidity that can be regarded as a rigid body with respect to the elastic force, connecting the pair of end plates together, and connecting the pair of end plates to each other, A connecting member for applying a force that balances the elastic force is provided, and the end plate and the connecting member are fastened by a fastening member inserted in a direction orthogonal to the laminating direction.

According to the fifth fuel cell, the unit cells can be sufficiently adhered to each other and stable operation can be realized while absorbing deformation due to heat by the elastic force of the elastic member. In the mechanism for applying the elastic force in this manner, the fifth fuel cell employs a structure in which the load applied to the end plate as a reaction of the elastic force applied to the unit cell is supported by the connecting member. here,
The fastening member between the connecting member and the end plate is inserted in a direction orthogonal to the laminating direction. When the fastening member is inserted in the stacking direction, the size of the product in both directions increases accordingly. When the fastening member is inserted in the direction orthogonal to the stacking direction, such increase in size can be avoided.

The above configuration is particularly useful in a fuel cell having a plurality of stacked cells, as shown below. In a fuel cell including a plurality of stacked cells, in order to uniformly supply fuel gas or the like to each unit cell, a supply port in the stacking direction,
Preferably, an outlet is provided. In particular, when a plurality of stacked batteries are connected using the above-described supply / discharge member, each stacked battery is connected to the supply / discharge member via one end plate. According to the fifth fuel cell, since the fastening member is inserted in the direction orthogonal to the stacking direction, it is possible to avoid interference of the fastening member on the coupling surface with the supply / discharge member. Further, even after the supply / discharge member and the stacked battery are connected, the fastening state of the fastening member can be checked, and thus the maintainability is also improved. Even when the supply / discharge member is not used, the same effect can be obtained to some extent.

Further, in the fifth fuel cell, when a plurality of the stacked batteries are provided, it is preferable that the stacked batteries are arranged in a direction orthogonal to the insertion direction of the fastening member. With such an arrangement, it is possible to avoid interference of the fastening members between the stacked cells, and to further reduce the size of the fuel cell. Further, maintainability can be improved. The fifth fuel cell is particularly useful when it has a plurality of stacked batteries as described above, but it goes without saying that the fifth fuel cell can be effectively applied to a single stacked battery.

In the above description, the fuel cells are individually described as the first to fifth fuel cells. However, various configurations of the fuel cells obtained by combining these inventions are also possible. Can be realized. The above-described invention is desirably applied to a polymer electrolyte fuel cell which is expected to be particularly miniaturized, but is not limited to this. For example, a phosphoric acid fuel cell, a molten carbonate fuel cell The present invention can be applied to various types of fuel cells such as a solid oxide fuel cell and an alkaline fuel cell.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in the following order based on examples. A. Overall configuration: B. Short circuit means for cooling system: Drainage mechanism: D. E. Insulation configuration of tension plate: F. Structure for fixing cells and arrangement of stacks: Outer case:

A. Overall Configuration: FIG. 1 is a perspective view showing a schematic configuration of a stack 10 of the present embodiment. Stack 10
It is formed in the form of a stacked battery in which a predetermined number of cells 100 as unit batteries that generate electromotive force are stacked. The stacked cells are connected to the tension plates 170, 1 arranged vertically.
72 and fixed. Each of the cells 100 is formed as a polymer electrolyte fuel cell, and each cell generates an electromotive voltage of a little over 1V. In this embodiment, 100 cells are stacked so that an electromotive voltage of about 100 V is generated in each stack. Although a detailed structure of the cell 100 will be described later, the cell 100 has a structure in which an oxygen electrode, an electrolyte membrane, and a hydrogen electrode are sandwiched by a separator in this order. In the stack 10, the separators of the adjacent cells 100 are shared. In general, the term “stack” may be used simply as a generic term for stacked cells, or may refer to a structure including members for fixing cells. In this specification, when simply referred to as the stack 10, it means the latter meaning, that is, a structure including the upper and lower tension plates 170 and 172 in addition to the stacked cells 100. Shall be called “stack in a narrow sense”.

The stack 10 is formed by stacking an end plate 12, an insulating plate 16, a current collecting plate 18, a plurality of cells 100, a current collecting plate 20, an insulating plate 22, and an end plate 14 in this order from one end. The end plates 12 and 14 are formed of a metal such as steel in order to secure rigidity.
The current collecting plates 18 and 20 are formed of a gas-impermeable conductive member such as a dense carbon or copper plate, and the insulating plates 16 and 22 are formed of an insulating member such as rubber or resin. The electric power generated in the stack 10 is output by connecting to the current collector plates 18 and 20.

One end plate 14 has a fuel gas supply port 35, a fuel gas discharge port 36, and an oxidizing gas supply port 3.
3, an oxidizing gas discharge port 34, a cooling water supply port 31, and a cooling water discharge port 32 are provided. The fuel gas supplied to the stack 10 from the fuel gas supply port 35 is supplied to the end plate 1.
2 and is distributed to each cell 100. The fuel gas distributed to each cell 100 is supplied to the end plate 1
After flowing toward the cell 2, it is distributed to each cell 100, flows through the flow path in the cell 100 from left to right in the drawing, flows toward the end plate 14, and is discharged from the fuel gas discharge port 36. Similarly, after the oxidizing gas is supplied from the oxidizing gas supply port 33, the oxidizing gas is distributed to each cell 100 while flowing toward the end plate 12, and flows through the flow path in each cell 100 from above to below in the drawing. Is discharged from the oxidizing gas discharge port 34. The cooling water is supplied from the cooling water supply port 31, passes through cooling separators provided at predetermined intervals, cools the cells, and is discharged from the cooling water discharge port 32. The gas flow path of each cell 100 is formed inside the stack 10 so that the flow of the gas and the cooling water can be realized. The electrolyte membrane 132 constituting each cell 100 of the stack 10 has a peripheral area in contact with the separators 110 and 120 sealed. This seal is located in cell 10
The fuel gas and the oxidizing gas leak from the inside of the fuel cell 0, and serve to prevent the two from mixing.

FIG. 2 is a perspective view showing the structure of the cell 100. The cell 100 is configured as a polymer electrolyte fuel cell. The cell 100 includes an electrolyte membrane 132 and a hydrogen electrode 13.
4. It has a structure sandwiched between oxygen electrodes 136 and further sandwiched between separators 110 and 120 on both sides. The oxygen electrode 136 is on the back side of the hydrogen electrode 134 with the electrolyte membrane 132 interposed therebetween,
In the figure, it exists on the hidden side. The hydrogen electrode 134 and the oxygen electrode 136 are gas diffusion electrodes. Separator 110,
120 has a plurality of uneven ribs formed on the surface facing the hydrogen electrode 134 and the oxygen electrode 136. Separator 11
The fuel gas flow path 112 is formed between the hydrogen electrode 134 and the oxygen electrode 136 by sandwiching the hydrogen electrode 134 and the oxygen electrode 136 from both sides. The separators 110 and 120 have ribs formed on both sides, one side forms a fuel gas flow path 112 with the hydrogen electrode 134, and the other side has an adjacent cell 10.
An oxidizing gas flow path 122 is formed between the oxygen gas 136 and the oxygen electrode 136 included in 0. Thus, the separators 110 and 120
In addition to forming a gas flow path with the gas diffusion electrode, the gas diffusion electrode plays a role in separating the flow of the fuel gas and the oxidizing gas between adjacent cells.

The electrolyte membrane 132 is a proton-conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and has good electric conductivity in a wet state.
As the electrolyte membrane 132, for example, a Nafion membrane (manufactured by DuPont) or the like can be used. Electrolyte membrane 132
Is coated with platinum as a catalyst. In this embodiment, carbon powder supporting platinum as a catalyst is dispersed in an organic solvent, and an electrolyte solution (for example, Aldric) is used.
h Chemical, Nafion Soluti
on) into a paste by adding an appropriate amount of
The catalyst was applied on the sample No. 32 by screen printing. Various other methods can be applied to the method of forming the catalyst layer. For example, a method may be used in which a paste containing carbon powder supporting the catalyst is formed into a film to form a sheet and pressed on the electrolyte membrane 132. Good. Also, an alloy composed of platinum and another metal can be used for the catalyst. The hydrogen electrode 134 and the oxygen electrode 136 are formed by carbon cloth woven from carbon fibers. Hydrogen electrode 134 and oxygen electrode 1
36 may be formed of carbon paper or carbon felt made of carbon fiber. Further, since the above-described catalyst may be interposed between the gas diffusion electrode and the electrolyte membrane 132, the electrolyte membrane of the hydrogen electrode 134 and the oxygen electrode 136 may be used instead of the method of applying the catalyst on the electrolyte membrane 132 side. A catalyst may be applied to the side in contact with 132.

The separators 110 and 120 are formed of a gas-impermeable conductive member, for example, a dense carbon which is made of gas by compressing carbon. A plurality of ribs arranged in parallel are formed on both surfaces of the separators 110 and 120. The ribs do not necessarily need to be formed in parallel on both surfaces, but can be formed at various angles such as being orthogonal to each surface. The rib does not necessarily have to be a parallel groove as long as it can form a flow path for the fuel gas and the oxidizing gas.

The separators 110 and 120 are formed with cooling water holes 151 and 152 having a circular cross section at two locations on the periphery thereof. The cooling water holes 151 and 152 are connected to the cell 1
When the layers 00 are stacked, a cooling water passage that penetrates the stack 10 in the stacking direction is formed. Near the sides of the separators 110 and 1120, elongated fuel gas holes 153 and 154 and oxidizing gas holes 155 and 156 are formed along the respective sides. The fuel gas holes 153 and 154 and the oxidizing gas holes 155 and 156 form the fuel gas passage 112 and the oxidizing gas passage 122 that penetrate the stack 10 in the stacking direction when the stack 10 is formed by stacking the cells 100. Form. In this embodiment, a fuel gas supply path is formed along the left side of FIG. 3, and a fuel gas discharge path is formed along the right side. An oxidizing gas supply path is formed along the upper side, and an oxidizing gas discharge path is formed along the lower side.

The fuel gas supply port 35 of the stack 10 is connected to a fuel gas supply path, and the fuel gas discharge port 36 is connected to a fuel gas discharge path. The fuel gas supplied from the fuel gas supply port 35 flows into the fuel gas channel 112 of each cell 100 through the fuel gas supply path. Then, after being subjected to a predetermined reaction at the hydrogen electrode 134, it flows out of the fuel gas discharge path to the fuel gas discharge port 36. The oxidizing gas flows through the same route. The oxidizing gas supply port 33 of the stack 10 is connected to an oxidizing gas supply path, and the oxidizing gas discharge port 34 is connected to an oxidizing gas discharge path. Oxidizing gas supply port 33
Is supplied to the oxidizing gas channel 122 of each cell 100 through the oxidizing gas supply path. And
After being subjected to a predetermined reaction at the oxygen electrode 136, it flows out of the oxidizing gas discharge path to the oxidizing gas discharge port 34.

In the stack 10, a cooling separator 140 is provided at a rate of one every five cells 100 are stacked. The cooling separator 140 is a separator for forming a cooling channel for cooling the cell 100.
The cooling separator 140 has a concavity-shaped cooling water groove 142 that connects the cooling water holes. Separator 11
The surface facing the cooling separator 140 is a flat surface without ribs, and the grooves provided in the cooling separator 140 are the separators 110 and 120.
And a cooling channel is formed between them. The separator 11
0, 120 and the cooling separator 140 can be formed of various conductive materials other than dense carbon. For example, it may be formed of a metal such as a copper alloy or an aluminum alloy with emphasis on rigidity and heat conductivity.
Further, the proportion of the cooling separator 140 provided can be set in a range suitable for cooling according to conditions such as the calorific value of the cell 100 according to the required output of the stack 10, the temperature and the flow rate of the cooling water, and the like.

The fuel cell 1 according to the present embodiment is configured by connecting the four stacks 10 described above. FIG. 3 is an exploded perspective view showing a schematic structure of the fuel cell 1. In the present embodiment, a configuration in which four stacks 10A to 10D are connected to two opposing surfaces of a rectangular parallelepiped supply / discharge box 200 is applied. The supply / discharge box 200 is connected to a fuel supply source, an oxidizing gas supply source, and a cooling water supply source. The fuel, the oxidizing gas, and the cooling water are respectively supplied to the stacks 10A to 10A through the supply / discharge box 200.
10D, each stack 10A
10D to 10D are collected into the supply / discharge box 200 and discharged outside.

FIG. 4 is an explanatory diagram showing the supply / discharge status of fuel gas, oxidizing gas and cooling water. The supply / discharge box 200 has fuel gas supply ports 3 provided in each of the stacks 10A to 10D.
5, holes communicating with the fuel gas outlet 36, the oxidizing gas supply port 33, the oxidizing gas outlet 34, the cooling water supply port 31, and the cooling water discharge port 32 are provided. In addition, stack 10A ~
The remaining four surfaces not joined to 10D are provided with holes for connecting to a fuel supply source, an oxidizing gas supply source, a cooling water supply source, and the like. Although the detailed description of the internal structure of the supply / discharge box 200 is omitted, the supply / discharge box 200 realizes supply / discharge of fuel gas, oxidizing gas, and cooling water to / from each of the stacks 10A to 10D through these holes. ing.

The cooling water is supplied to the supply / discharge box 2 as shown in the figure.
The water is supplied / discharged through a water supply port 201 and a water discharge port 202 provided on the upper surface of the fuel cell 00. Inside the supply / discharge box 200, a flow path for distributing the cooling water supplied from the water supply port 201 to the cooling water supply port 31 of each stack and supplying the cooling water discharged from the cooling water discharge port 32 of each stack. Drain water 20
2 are formed. The cooling water supplied from the outside is supplied to the stack along a path indicated by a solid arrow in the drawing, and is discharged from the stack along a path indicated by a broken line.
Here, in order to avoid complication of the drawing, the cooling water path is shown only for the stack 10C, but the stack 10A,
The same applies to 10B and 10D.

As shown in the figure, the oxidizing gas is supplied through a supply port 203 provided on the upper surface of the supply / discharge box 200, and is discharged from a discharge port provided on the lower surface. The oxidizing gas supplied to the supply port 203 is supplied to the inside of the supply / discharge box 200 by the oxidizing gas supply port 33 of each of the stacks 10A to 10D.
And a flow path for distributing and supplying the fluid. Further, a flow path is provided for collecting the oxidizing gas discharged from the oxidizing gas discharge port 34 of each of the stacks 10A to 10D into the discharge port. The oxidizing gas supplied from the outside is supplied to the stacks along a path indicated by an arrow in the drawing, and is discharged from each stack. Although the path of the oxidizing gas is shown only for the stacks 10A and 10D to avoid complicating the drawing, the same applies to the stacks 10B and 10C.

The fuel gas is supplied to the supply / discharge box 2 in FIG.
00, and is discharged from a discharge port 204 provided on the front side in FIG. Inside the supply / discharge box 200, a flow path for distributing and supplying the fuel gas supplied to the supply port to the fuel gas supply port 35 of each of the stacks 10A to 10D is provided. Further, a flow path for collecting the fuel gas discharged from the fuel gas discharge port 36 of each of the stacks 10A to 10D into the discharge port 204 is provided. The fuel gas supplied from the outside is supplied to the stacks along a path indicated by an arrow in the drawing, and is discharged from each stack. Here, in order to avoid complication of the figure, the path of the oxidizing gas is shown only for the stacks 10A and 10D,
The same applies to 0C.

The stacks 10A to 10D are connected in series. Since each stack generates an electromotive voltage of about 100 V, the fuel cell of this embodiment has about 4
An electromotive voltage of 00V is realized. In the present embodiment, a configuration in which the stacks are connected using the supply / discharge box 200 is employed, but various other structures can be applied to the connection of the stacks. Also, the number of stacks can be variously set according to the required voltage. The fuel cell according to the present embodiment includes a supply / discharge box 200 and four stacks 1.
0A to 10D are housed in one outer case. The structure of the outer case will be described later. The general schematic configuration of the fuel cell has been described above. Hereinafter, the characteristic configuration of the fuel cell according to the present embodiment will be described separately in each section.

B. Short-circuit means of cooling system: FIG. 5 is an explanatory view showing the concept of short-circuit means provided in the cooling system. FIG.
As described in the above, in the fuel cell of this embodiment, the four stacks 10A to 100D are connected via the supply / discharge box 200, and the supply / discharge box 200 distributes cooling water to these four stacks. Water inlets and outlets are provided for centralized water supply and drainage. FIG. 4 shows the structure provided on the upper surface of the water supply / discharge box 200, but here, in order to avoid complication of the drawing when illustrating the features of the short-circuit means, the water supply port 201A and the water discharge port 202A are provided on the side surfaces. Is provided.

In this embodiment, a short-circuit cable 210 is provided between the water supply port 201A and the drain port 202A thus provided as a short-circuit means for electrically short-circuiting the two. In this embodiment, the water inlet 201A and the drain 20
In order to reliably short-circuit 2A, a short-circuit cable 210 of a conductive wire was fixed so as to be wound around both. The short-circuit cable 210 is fixed by using a water supply port 201A and a drain port 202A.
Can be performed in various modes that can be electrically short-circuited. For example, both may be soldered at one point, or may be bolted. In addition, the short-circuit cable 21
0 does not necessarily need to be formed of a conductive wire.
01A, a conductive plate having a hole through which the drain port 202A penetrates may be used. As the short-circuit means, in addition to connecting the water supply port 201A and the drain port 202A with a conductive member as described above, it is also possible to adopt a method in which both are brought into contact with each other so as to be short-circuited. Further, it may be formed on the surface of the supply / discharge box 200 by etching or the like in the same manner as the printed circuit board.

The operation of the short-circuit cable 210 is as follows. As described with reference to FIG. 2, the cooling water supplied to the stack cools the cells by passing through the cooling separator. However, since the cooling separator is formed of a conductive member, the cooling water is cooled during cooling. Is charged according to the potential of. As a result, the cooling water inlet 201A and the drain 202
A and A may cause a potential difference in the cooling water. FIG. 5 shows the flow of the cooling water in this embodiment. As shown in the figure, the cooling water supplied from the water supply port 201A is
After being distributed to A to 10D and cooling the respective stacks, they are collected and discharged from the drain port 202A. Here, in this embodiment, since four stacks are connected in series, the potential increases from the stack 10A to the stack 10D in steps of 100V. Therefore, as shown,
The cooling water for cooling the stacks 10A and 10B is about 100V
And the cooling water that has cooled the stacks 10C and 10D is charged to about 300V. As a result, water supply port 2
A potential difference of about 200 V is generated between 01A and the drain port 202A.

According to the present embodiment, since the water supply port 201A and the water discharge port 202A are electrically short-circuited by the short-circuit cable 210, the potential difference between the two can be eliminated. Therefore, according to the present embodiment, the water supply port 20
It is possible to avoid adverse effects such as electrolytic corrosion caused by a potential difference generated between 1A and the drain port 202A. Further, since the short-circuit means can be realized relatively easily as described above, there is no adverse effect such as an increase in the size of the fuel cell and an increase in the manufacturing cost. This also makes it possible to avoid an increase in the size of the device due to the provision of insulating members at the supply port and the discharge port. Further, since there is no restriction such as providing both at a portion where there is no potential difference, the degree of freedom in design is increased and the size of the device can be further reduced.

In this embodiment, the short-circuit cable 2 is connected between the water supply port 201A and the water discharge port 202A of the supply / discharge box 200.
10 was connected. Although the short-circuit cable may be provided for each stack, the use of the supply / discharge box 200 suffices to install the short-circuit cable 210 at a single location, which facilitates the installation of the short-circuit cable 210 and also causes troubles such as disconnection. There is an advantage that the work load can be reduced, such as easy handling of the case.

A modification of the method of installing the short-circuit cable 210 will be described. FIG. 6 is an explanatory diagram showing a method of installing the short-circuit cable 210 as a first modification. Here, plan views of the stacks 10A to 10D and the supply / discharge box 200 are shown. The first modification differs from the embodiment in that a water supply port 201B and a drainage port 202B are provided on opposing surfaces of a supply / discharge box 200 as shown in the figure. In such a case, the short-circuit cable 210 is connected to the supply / discharge box 2
What is necessary is just to install so that the water supply port 201B and the drainage port 202B may be short-circuited so that it may cross 00. In this case, it is convenient to install the short-circuit cable so as to pass through the outside of the supply / discharge box 200, but the short-circuit cable may cross the inside.

FIG. 7 is an explanatory view showing a method of installing a short-circuit cable 210 as a second modification. In the embodiment, the short-circuit cable 210 is fixed to the supply / discharge box 200.
Here, the case of fixing to each stack is illustrated. FIG.
As is clear from the above, in the configuration of the present embodiment, when viewed from each stack, since water is supplied and drained from a portion having the same potential, no potential difference occurs in the cooling water. However, as shown in FIG.
C, when the drain port 202C is provided, a potential difference occurs. The second modification can be applied to such a case, and the short-circuit cable 210 is connected to the water supply port 2 so as to traverse the stack.
01C and a drain port 202C are provided so as to be connected to each other.

In the first modified example and the second modified example, similarly to the embodiment, the short-circuit means can be provided in various modes. The short-circuit means is not limited to the modes illustrated in the examples and the modifications, and can be provided in various modes depending on the portion where the potential difference exists.

C. Drainage mechanism: Fig. 8 shows fuel gas outlet 2
It is explanatory drawing which shows the drainage mechanism provided in 04. FIG. 4 is a cutaway diagram when the supply / discharge box 200 of the present embodiment is cut along a plane including a gas discharge port 204. In order to avoid complication of the drawing, the cross section shows only the vicinity of the discharge port 204. As described above, each of the stacks 10A to 10A
The fuel gas discharged from D is collected in the supply / discharge box 200 and discharged to the outside from the gas discharge port 204. FIG.
Shows the flow path after the gas from each stack was collected.

As shown in the figure, the gas flow path is
4 and a drain port 205 is provided. The flow path from the branch to the drain port only needs to be formed in a state in which water can flow, and can be appropriately provided at a position that does not interfere with other flow paths provided in the supply / discharge box 200. Although FIG. 8 illustrates the flow path bent in an L-shape, the flow path may be configured in a curved shape. In the present embodiment, as described later, the bent part of the L-shaped flow path serves as a water storage part for temporarily storing water droplets. The drainage flow path is provided near the gas outlet 204, and the static pressure AP locally increased at the joint where another pipe is connected to the outlet 204 is supplied to the water storage unit. It is provided at a position that sufficiently acts on the water surface of the stored water droplets.

The operation of the drainage mechanism is as follows. Since the fuel cell generates power based on the equations (1) and (2) shown in the prior art, water is generated as a result of the power generation.
Further, in the present embodiment, a polymer electrolyte fuel cell is used, and in order to generate power, it is necessary to appropriately humidify the electrolyte membrane of each cell. As a result, the fuel gas that has passed through the cell contains a considerable amount of water droplets. In a fuel cell, since fuel gas is supplied to each cell at a relatively high pressure, these water droplets are discharged from the outlet 204 by the gas pressure.
Transported to However, the resulting water droplets
It must be exhausted in any part of the fuel gas flow path. This is because if water droplets remain in the gas flow channel, the water droplets may adhere to the inner surface of the gas flow channel and hinder the supply and discharge of the fuel gas. The drainage mechanism of the present embodiment has an effect of discharging water droplets mixed into the discharged gas to the outside.

The water droplets carried near the fuel gas outlet 204 flow into the flow path on the drain port side. The bent portion of the L-shaped channel serves as a water storage unit 206 for temporarily storing these water droplets. The flow path on the drain port side is desirably provided below the gas flow path so that water drops can flow efficiently by the action of gravity. The water droplets thus accumulated are sequentially discharged from the drain port 205.

Such a drainage mechanism can be provided at any part of the flow path for discharging the fuel gas, or can be provided outside the fuel cell. However, in this embodiment, each stack 1
There is a great feature in that the gas exhausted from 0A to 10D is provided at a portion after being collected. By providing such a portion, water droplets can be efficiently discharged by a single drainage mechanism. Further, since the drainage mechanism only needs to be provided at one location, the configuration of the apparatus can be simplified and the size can be reduced. By providing the inside of the supply / discharge box 200, there is no need to provide a drain valve or the like outside, and the apparatus can be further downsized.

Further, the drainage mechanism of this embodiment has an advantage that water droplets can be efficiently discharged by utilizing not only gravity but also pressure of fuel gas. As described above, in the present embodiment, the water storage unit 206 is provided in the drain passage, and the gas pressure AP is applied to the water surface stored here.
Is configured to operate sufficiently. Since the fuel gas is supplied to each stack at a high pressure, the generally discharged fuel gas is also at a higher pressure than the atmospheric pressure. Therefore, by applying this pressure to the surface of the water droplets stored in the water storage section 206, water can be positively and efficiently discharged. By making it possible to drain using the pressure of the gas as described above, the diameter of the drain port 205 can be reduced, and the size of the apparatus can be reduced.

In the present embodiment, a configuration is adopted in which a branch is provided in the vicinity of the gas discharge port 204 so that the static pressure AP capable of efficiently discharging water acts on the water storage section 206.
The position and shape of the branch can adopt various modes in which the pressure of the gas can be applied. For example, a branch may be provided at a portion where the gas flow path is bent and the pressure is locally increased, or the branch is connected at an acute angle to the flow direction of the exhaust gas, and the dynamic pressure of the gas acts. You may do so. Of course, the configuration using the pressure of the gas is not essential, and a mechanism for draining only by gravity may be used.

By draining using the gas pressure, there is also an advantage that the degree of freedom for the position of the drain port is increased. An example of a drainage port utilizing this advantage will be described as a modification. FIG. 9 is an explanatory diagram showing a drainage mechanism as a modification. The modification differs from the embodiment in that the drain port 205 is provided above the gas outlet 204. As shown in the figure, the flow path leading to the drain port branches from the flow path for discharging gas at the same site as in the embodiment. The branch part is provided below the flow path for discharging gas, as in the embodiment. This branch part constitutes the water storage part 206A. In a modified example, a drain passage 207 is provided in the water storage section 206A so as to open inside and communicate with the drain port 205A. When the pressure AP of the discharged gas acts on the water surface of the water storage section 206A, since this pressure is higher than the atmospheric pressure, water droplets pass through the drain passage 207 and drain port 205A.
Is discharged from By providing the water storage section 206A at the location where the gas pressure acts, the drainage port 205A can be provided at an arbitrary location. Therefore, the degree of freedom for the position of the drain port 205A is increased, and the size of the entire apparatus can be reduced by design. Also in the modified example, as described in the embodiment,
The water storage section 206A can be provided in various modes in which gas pressure can be applied.

FIGS. 8 and 9 show the drainage mechanism for the fuel gas discharge section. It is necessary to drain the oxidizing gas as well as the fuel gas. In this embodiment, a drainage mechanism similar to the fuel gas is provided also in the flow path of the oxidizing gas. For such a mechanism, the mechanism of the modified example (FIG. 9) can be applied.

D. Insulation configuration of tension plate: Fig. 1
0 is an explanatory view showing the structure of the tension plate. Here, among the tension plates shown in FIG. 1, only the tension plate 172 provided on the lower surface of the stack 10n in a narrow sense is shown. Since the tension plate 170 provided on the upper surface also has the same configuration, illustration and description are omitted below.

The tension plate 172 is provided with an insulating layer 174 on the surface in contact with the stack in a narrow sense in which cells are stacked. In this embodiment, the insulating layer 174 is formed by bonding a silicon rubber sheet. The material of the insulating layer 174 is not necessarily limited to a silicon rubber sheet, and various materials having an insulating effect can be applied. When a silicon rubber sheet is used, there is an advantage that the stack 10n in a narrow sense can be isolated from vibration in addition to the insulating action. When it is not necessary to insulate the stack 10n in a narrow sense and the tension plate 172 again, such as when the tension plate 172 is formed of an insulating material, the insulating layer 174 is used to perform only the vibration damping action. It may be provided as a vibration layer. Further, the insulating layer 174 may be formed by coating instead of bonding. As described above, the insulating layer 174 can be formed by various materials and methods depending on which of the insulating function and the vibration-proof function is performed.

The use of the tension plate 172 of this embodiment has an advantage that the process of manufacturing the stack 10 can be simplified. For example, when the insulating layer 174 is separately provided, a step of inserting an insulating material between the stack 10n in a narrow sense and the tension plate is required. However, if the tension plate 172 of this embodiment is used, such a step is required. It can be omitted. The process of stacking the cells to form the stack 10 is a precision operation that greatly affects the performance of the fuel cell.
This leads to a significant increase in productivity.

By forming the insulating layer 174 integrally with the tension plate 172, there is also an advantage that the stack 10 can be reduced in size for the following reason. First, when the insulating material is prepared separately, the insulating material itself tends to be thick in order to maintain its shape. However, as in the present embodiment, the insulating layer 174 is integrally formed on the tension plate 172. Then, the thickness can be reduced. In addition, a dimensional error in thickness can be suppressed. Second, when the insulating material is prepared separately, even if the position of the insulating material is shifted, the stack 10 in a narrow sense is used.
It is necessary to provide a sufficient gap so that the n and the tension plate 172 do not come into contact with each other. However, if the insulating layer 174 is formed integrally with the tension plate 172 as in the present embodiment, such a gap can be obtained. No consideration is required, and the gap between the two can be reduced. By these effects, the use of the tension plate 172 described in the present embodiment makes it possible to reduce the size of the stack 10 and, consequently, the entire fuel cell.

Here, a configuration in which the tension plates 170 and 172 are arranged above and below the stack 10 (see FIG. 1)
However, the configuration in which the insulating layer is integrally formed can be applied to various structures such as a case in which a box-shaped case that completely accommodates the stack 10 is used and a case in which four surfaces of the stack 10 are fixed by plates. Can be applied.

E. Cell fixing structure and stack arrangement: FIG. 11 is an explanatory view showing a cell fixing structure. As described above, the stack 10 is fixed with the upper and lower portions sandwiched between the tension plates 170 and 172. Here, the fixing method will be described in more detail.

FIG. 11A is a perspective view of the stack 10 as viewed from the end plate 12 side. As shown, the end plates 12 and 14 of the stack 10 are fastened to the tension plate 170 by eight bolts 175 inserted vertically in the drawing. Although not shown in the perspective view, the lower surface of the tension plate 172 is similarly fastened by eight bolts inserted vertically. The end plate 12 has a protrusion 12A near the center.

FIG. 11B is a sectional view of the stack 10 taken along the line AA. As described above, the stack 10 is formed by stacking many cells 100. The cell 100 is fixed such that both ends thereof are sandwiched between end plates 12 and 14. One end of cell 100 and end plate 12
And a disc spring 220 is inserted between them. The central portion of the end plate 12 is deformed into a tray shape so as to prevent the disc spring 220 from shifting. The protrusion 12A is an appearance of this deformation. The disc spring 220 is located in the cell 1
00 is inserted so as to urge the elastic force EF in the direction in which the 00 comes into close contact.

When the disc spring 220 exerts an elastic force on the cell 100, the reaction F1, F2 is generated by the end plate 1.
Work on 2,14. In this embodiment, as shown in FIG. 11A, the tension plates 170 and 17 fixed vertically
2 is an elastic force TF1, T balanced with the reaction F1, F2.
By making F2 act on the end plates 12 and 14,
The whole structure is established. End plate 12, 1
4 is made of a material and a plate thickness capable of maintaining sufficient rigidity against the elastic force.

The operation of the above structure is as follows.
Since the cells 100 are brought into close contact with each other by the elastic force EF of the disc spring 220, the internal resistance caused by the gap between the cells and the like can be reduced. Although the cell 100 is deformed by heat during power generation, the disc spring 220 can make the cell 100 adhere to each other while absorbing this deformation, so that the fuel cell of this embodiment can always realize stable power generation. . The disc spring 220 may have an elastic force and a size appropriately selected so as to sufficiently perform such an operation.

Further, the tension plates 170 and 172
By fastening the end plates 12 and 14 with bolts inserted in the vertical direction in the drawing, that is, in the direction perpendicular to the stacking direction of the cells 100, the apparatus can be downsized as described below. There is also. Since the bolt is inserted in the first direction, it is possible to prevent the head of the bolt from protruding in the stacking direction, and accordingly, there is an advantage that the size of the stack 10 in the stacking direction can be suppressed. Since a plurality of cells are stacked in order to secure a voltage, the stack 10 generally has a longer length in the stacking direction. In general, when the fuel cell is mounted on a device such as a vehicle, the stack 10 is particularly stacked. Since strict requirements are often imposed on the dimensions of the layers, shortening the stacking direction is significant.

Further, as shown in FIG. 1, the fuel cell of this embodiment has four stacks 10A to 10
10D. In each stack, when a bolt for fixing the cell projects in the stacking direction, it interferes with the supply / discharge box 200, and a configuration for avoiding this interference is required. There is a possibility that the configuration of the discharge box 200 may be complicated. On the other hand, according to the stack of the present embodiment, each of the stacks 10A to 10D can be connected to the supply / discharge box 200 without interference of the bolts, so that the structure can be simplified and downsized.

The above-described effects are obtained by inserting bolts in a direction perpendicular to the laminating direction. In the present embodiment, the size of the apparatus is further reduced by devising the arrangement of the plurality of stacks. FIG.
FIG. 4 is an explanatory diagram showing the arrangement of stacks in the present embodiment. As shown in FIG. 1, the fuel cell of this embodiment is configured by connecting four stacks 10A to 10D to a supply / discharge box 200. Here, among them, stack 1
The arrangement of 0A and 10D is illustrated. Stacks 10B, 10
C is also arranged according to this.

As shown, in this embodiment, two adjacent
The stacks 10A and 10D are arranged in a direction orthogonal to the direction in which the bolts 175 are inserted. By arranging in this manner, the stacks 10A and 10D can be arranged closely without interference between the bolts 175, so that the overall size of the fuel cell can be reduced. FIG.
FIG. 7 is an explanatory view showing a state where the stack is arranged in a direction in which the bolt 175 is inserted. FIG. 13A is a perspective view when the stack 10D is stacked on the stack 10A. FIG. 13B is a side view in such a case. When the stacks are arranged in the vertical direction as described above, FIG.
As shown in FIG. 3B, in the regions B1 and B2 between the stacks 10A and 10D, the bolts 175 interfere with each other, so that the stacks 10A and 10D cannot be arranged in close contact with each other, resulting in an increase in size. Will be. On the other hand, as shown in FIG. 12, if the stacks 10A and 10D are arranged in a direction orthogonal to the insertion direction of the bolt 175,
The distance between them can be narrowed.

The stacks 10A and 10D may be arranged in any direction as long as interference between the bolts 175 can be avoided.
As shown in FIG. 2, there is no limitation to the arrangement in which the stacking directions of the cells of the stacks 10A and 10D are parallel.
The stacks 10A and 10D may be arranged side by side in the cell stacking direction.

In this embodiment, the tension plate 170
Is exemplified by a rectangular plate, but the shape of the tension plate 170 is not limited to this. FIG. 14 is an explanatory view showing a modification of the tension plate. The tension plate 170A of the modified example is formed in an H shape having a large width at both ends coupled to the end plate and a small width near the center. Even with such a shape, the elastic force TF1, T
Since F2 can act, a stack can be formed. Modified tension plate 170
According to A, when thermal deformation occurs in the cell 100, the modification of the tension plate 170A due to the tensile loads F1 and F2 acting through the end plate becomes larger than that of the embodiment. That is, besides the disc spring, the tension plate 1
The effect of absorbing the thermal deformation of the cell 100 can also be achieved by 70A. As a result, the excess or deficiency of the elastic force of the disc spring can be compensated for by the tension plate 170A, the selection range of the disc spring can be expanded, and the manufacturing cost of the fuel cell can be reduced. Tension plate 17
0 is not limited to the shape exemplified here, but can be configured with various plate thicknesses and shapes according to the demand of elastic force.

In the present embodiment and the modified example, the structure in which the end plate for sandwiching the cell via the disc spring is supported from above and below by the tension plate is illustrated. The first feature of this embodiment is that a bolt for fastening a tension plate is inserted in a direction perpendicular to the laminating direction. If the bolt is inserted in such a direction, a tension plate is further provided in the left-right direction. It is possible to adopt a structure, a structure in which tension plates are provided on four surfaces, up, down, left, and right. If the rigidity between the end plate and the tension plate can be sufficiently ensured, the cells may be fixed by tension plates provided only on one of the upper, lower, left, and right sides. In addition, in the present embodiment and the modified example, the case of fastening with the bolt is illustrated, but the fastening member is not limited to these. Also, the member for applying the elastic force is not limited to the disc spring, and various springs and rubber sheets can be used as appropriate.

F. Outer case: As described in the description of the overall configuration, the fuel cell 1 of this embodiment is housed in the outer case. FIG. 15 is an explanatory diagram showing a state where the fuel cell is housed in the outer case. FIG. 15A is a perspective view showing a state in which the fuel cell 1 is housed. The broken line in the figure indicates the fuel cell 1. As shown, the outer case is composed of a main body 2 and a lid 3. A drain hose 5 is attached to the main body 2, and an exhaust hose 4 is attached to the lid 3. Although a pipe for supplying and discharging fuel gas, oxidizing gas, and cooling water to and from the fuel cell 1 is connected to the outer case, it is not shown here to avoid complication of the drawing.

FIG. 15B is a cross-sectional view taken along the line BB of the perspective view. The hatched portions in the figure correspond to the fuel cell 1. The main body 2 and the lid 3 of the outer case are hermetically sealed by a seal 6 at a joint surface. In this embodiment, the outer case is sealed to prevent foreign matter such as water and dust from entering the fuel cell 1 from the outside. In this embodiment, the silicone rubber is applied to the seal 6.
As long as it meets the above purpose, it is possible to seal with various materials and methods. For example, the main body 2 and the lid 3 may be welded, or the main body 2 and the lid 3 may be crimped or the like. May be fixed.

The drain hose 5 is a hose for discharging water accumulated in the outer case for some reason, and is fixed to a hole provided at a lower portion of the main body 2 with a stopper. The exhaust hose 4 is a hose for discharging various gases accumulated in the outer case, and is fixed to a hole provided at an upper portion of the lid 3 with a stopper. The drain hose 5 and the exhaust hose 4 have a structure that can prevent foreign substances such as water and dust from entering from outside. In the present embodiment, such an effect is achieved by making the length of these hoses sufficiently long and bending them appropriately. In order to more reliably prevent intrusion of foreign matter, a valve body may be provided at a portion where these hoses are attached. In addition,
The drain hose 5 and the exhaust hose 4 are not essential for the outer case. When the necessity is low, for example, when the possibility that water or various gases are generated from the fuel cell inside the outer case is low, at least these are used. One may be omitted.

The operation of the outer case is as follows.
First, the intrusion of foreign matter can be prevented by housing the fuel cell 1 in the outer case. Therefore, it is possible to prevent the foreign matter from entering between the cells and lowering the power generation efficiency. Further, the fuel cell 1 does not need to take measures against foreign substances such as completely covering the surroundings, so that the overall structure can be simplified and the size of the stacked battery can be reduced. At the same time, it is possible to improve the productivity of the fuel cell and reduce the manufacturing cost.

The outer case also has the advantage that the rigidity can be ensured without increasing the weight or increasing the size of the fuel cell. The axes Ax and Ay in FIG. 15 represent neutral axes in bending deformation in the vertical and horizontal directions, respectively. In order to configure the fuel cell 1 with sufficient bending rigidity, it is desirable to make the moment of inertia about these neutral axes Ax and Ay sufficiently large. Here, since the distance from the neutral axes Ax, Ay to the outer periphery of the fuel cell itself is generally small, the second moment of area is smaller than that of the outer case. Therefore, in order to ensure sufficient bending rigidity when the outer case is not used, it is necessary to increase the thickness of the fuel cell 1, particularly, the thickness of the tension plate. On the other hand, since the outer case can secure a sufficient distance from the neutral axes Ax and Ay to the outer periphery, the second moment of area is large. Therefore, sufficient bending rigidity can be ensured even with a relatively thin plate thickness. When the outer case has a sufficient bending rigidity, a bending load hardly acts on the fuel cell 1, so that the thickness of the fuel cell 1 can be reduced.

The load acting on the fuel cell 1 includes a torsional load in addition to the bending load described above. In order to ensure sufficient rigidity against torsional load, the central axis of torsion,
That is, in FIG. 15, it is desirable to increase the secondary moment of area with respect to the intersection of the neutral axes Ax and Ay. The secondary polar moment of area increases as the distance from the central axis to the outer periphery increases. Therefore, when the outer case is used, a larger secondary moment of area can be realized as compared with the case of a single fuel cell. As a result, the outer case can secure sufficient torsional rigidity with a relatively thin plate thickness. When the outer case has a sufficient torsional rigidity, almost no torsional load acts on the fuel cell 1, so that the thickness of the fuel cell 1 can be reduced.

With these functions, sufficient rigidity can be easily secured by using the outer case, so that the thickness of the fuel cell 1 can be reduced, and the weight and size can be reduced. it can. Although the volume is larger than that of the fuel cell alone by using the outer case, the periphery of the fuel cell 1 is fuel gas,
Since a predetermined space is usually required for the piping for supplying and discharging the oxidizing gas and the cooling water, eliminating the disadvantage of increasing the volume by appropriately arranging these pipings in the outer case. can do.

The outer case can be formed in various shapes other than that shown in FIG. FIG. 16 is a perspective view showing an outer case as a first modification. In the embodiment, the fuel cell 1 is almost completely accommodated in the main body 2 and the lid 3 is covered. On the other hand, in the modified example, the main body 2
A was formed relatively small, and the lid 3A was enlarged. For example, when the fuel cell, the oxidizing gas, the cooling water, and the like are sufficiently provided around the fuel cell and housed in the outer case, in a modified example, after the fuel cell is housed in the main body 2A, the lid 3A
Before covering, most of the fuel cell is in an exposed state, so that there is an advantage that the above-mentioned piping work can be performed easily and reliably. As for the dimensions of the main body and the lid, it is not necessary to increase one of them as in the embodiment or the first modification, and they may be formed in the same size.

FIG. 17 is a perspective view showing an outer case as a second modification. In the embodiment and the modification, the case where the outer case is constituted by the main body and the lid is illustrated. That is, the case where the vertically divided members are combined to form the outer case is illustrated. The outer case is not necessarily required to have such a configuration, and may be configured by, for example, combining two members divided into right and left. Such a configuration corresponds to a second modification. The outer case is
It is a structure that can prevent foreign substances such as water and dust from entering the internal fuel cell, and various structures other than those exemplified here can be applied as long as the structure is suitable for securing rigidity. it can.

Of course, if a high degree of rigidity is not required depending on the situation in which the fuel cell is mounted, an outer case only for the purpose of intrusion of foreign matter may be used. In such a case, a relatively small outer case can be used. Further, since rigidity is not required, it can be formed using a resin.

According to the fuel cell of the present embodiment described above, first, it is possible to suppress the adverse effects caused by the potential difference generated in the cooling water by the short circuit means of the cooling system. Secondly, the drainage mechanism can prevent poor power generation and unstable operation due to so-called flooding. Thirdly, the insulation configuration of the tension plate can improve the productivity when manufacturing the fuel cell. Fourth, by the structure for fixing the cells and the arrangement of the stack, an appropriate elastic force is applied to the cells of the fuel cell, and it is possible to avoid lamination failure between the cells. Fifth, by using the outer case, it is possible to prevent foreign matter from entering the fuel cell.
Further, in the fuel cell according to the present embodiment, the above-described effects are realized by the configuration in consideration of the miniaturization of each device. Therefore, according to this embodiment, the practicability when mounting the fuel cell on various devices can be greatly improved.

In the above-described embodiment, a case where all of the five features, that is, the short-circuit means of the cooling system, the drainage mechanism, the insulating structure of the tension plate, the structure for fixing the cells and the arrangement of the stack, and the outer case are illustrated. However, each of these features can be applied individually. The above-described means may be selectively applied as appropriate according to the problem to be solved by the fuel cell actually used. Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that various configurations can be adopted without departing from the spirit of the present invention.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a stack 10 of the present embodiment.

FIG. 2 is a perspective view showing the structure of the cell 100.

FIG. 3 is an exploded perspective view showing a schematic structure of the fuel cell 1.

FIG. 4 is an explanatory diagram showing a supply / discharge state of fuel gas, oxidizing gas, and cooling water.

FIG. 5 is an explanatory diagram showing the concept of a short-circuit means provided in a cooling system.

FIG. 6 is an explanatory diagram showing a method of installing a short-circuit cable 210 as a first modification.

FIG. 7 is an explanatory diagram showing a method of installing a short-circuit cable 210 as a second modification.

FIG. 8 is an explanatory diagram showing a drainage mechanism provided at a fuel gas outlet 204.

FIG. 9 is an explanatory view showing a drainage mechanism as a modification.

FIG. 10 is an explanatory view showing the structure of a tension plate.

FIG. 11 is an explanatory diagram showing a structure for fixing a cell.

FIG. 12 is an explanatory diagram showing an arrangement of stacks in the present embodiment.

FIG. 13 is an explanatory view showing a state where the stack is arranged in a direction in which the bolt 175 is inserted.

FIG. 14 is an explanatory view showing a modification of the tension plate.

FIG. 15 is an explanatory diagram showing a state in which the fuel cell is housed in an outer case.

FIG. 16 is a perspective view showing an outer case as a first modified example.

FIG. 17 is a perspective view showing an outer case as a second modified example.

[Explanation of symbols]

 2, 2A: Main body 4: Exhaust hose 5: Drain hose 6: Seal 10, 10A, 10B, 10C, 10D: Stack 10n: Stack 12: End plate 12A: Protrusion 14: End plate 16: Insulating plate 18, 20 ... Current collecting plate 22 ... Insulating plate 31 ... Cooling water supply port 32 ... Cooling water discharge port 33 ... Oxidizing gas supply port 34 ... Oxidizing gas discharge port 35 ... Fuel gas supply port 36 ... Fuel gas discharge port 100 ... Cell 110 ... Separator 112 ... Fuel gas channel 122 ... Oxidizing gas channel 132 ... Electrolyte membrane 134 ... Hydrogen electrode 136 ... Oxygen electrode 140 ... Cooling separator 142 ... Cooling water groove 151 ... Cooling water hole 153 ... Fuel gas hole 155 ... Oxidizing gas hole 170, 170A … Tension plate 172… tension plate 174… insulation layer 175… bolt 200… supply / discharge box 01, 201A, 201B, 201C ... water supply port 202, 202A, 202B, 202C ... drain port 203 ... supply port 204 ... discharge port 205, 205A ... drain port 206A ... water storage section 206 ... water storage section 207 ... drain flow path 210 … Short circuit cable 220… Disc spring

Continued on the front page (72) Inventor Hideyuki Tanaka 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hiroshi Hotta 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference 5H026 AA06 CC03 CC08 CX08

Claims (8)

[Claims] 1. A fuel cell including a stacked battery in which unit cells are stacked, a mechanism for cooling by passing a conductive refrigerant through the stacked battery, and supplying the refrigerant to the stacked battery. Outlet, and an outlet for discharging the refrigerant from the stacked battery,
A cooling mechanism provided at a portion having a different electric potential, and a coolant path through which the coolant flows, and electrically short-circuits a coolant path upstream of the supply port and a coolant path downstream of the discharge port. A fuel cell provided with a short-circuit means for causing a short-circuit. 2. The fuel cell according to claim 1, wherein the fuel cell includes a plurality of the stacked batteries, and the coolant path is at least a part of a coolant path upstream of a supply port of each stacked battery. , And at least a part of the refrigerant path downstream of the outlet of each of the stacked batteries is configured as a common refrigerant path, and the short-circuit means is provided at a location configured as a common refrigerant path for the plurality of stacked batteries. A fuel cell, which is provided. 3. A fuel cell comprising a plurality of stacked batteries in which unit cells are stacked, wherein the plurality of stacked batteries, a function of distributing a supplied fuel gas to each of the stacked batteries, and an exhaust from each of the stacked batteries are provided. A supply / discharge member that realizes supply / discharge of fuel between the outside and each of the stacked batteries by performing a function of condensing gas; and the supply / discharge member has an internal structure in which the collected exhaust gas flows. A fuel cell, which is a structure including a gas flow path, and a drainage mechanism that branches off from the aggregated gas flow path and discharges water droplets in the gas flow path. 4. A fuel cell including a stacked battery in which unit cells are stacked, wherein the stacked battery includes a fixing member for fixing the stacked unit cells, and the fixing member contacts the unit cell. A fuel cell, wherein an insulating layer is provided integrally on the surface on the side of the fuel cell. 5. A fuel cell comprising a stacked battery in which unit cells are stacked, wherein the plurality of stacked batteries and the plurality of stacked batteries are collectively housed and sealed so as to prevent foreign matter from entering from outside. A fuel cell comprising: a container having a structured structure. 6. The fuel cell according to claim 5, further comprising a mechanism for supplying and discharging a fuel gas, an oxidizing gas, and cooling water to and from the stacked battery in a container. A fuel cell having a discharge mechanism for discharging gas or liquid generated in a container to the outside of the container. 7. A fuel cell including a stacked battery in which unit cells are stacked, wherein the stacked battery includes: an elastic member that applies elastic force to the unit cell in a stacking direction; A pair of end plates arranged in parallel with the cell and having a rigidity that can be regarded as a rigid body with respect to the elastic force; connecting the pair of end plates to each other to apply a force to the end plates to balance the elastic force; A fuel cell, comprising: a connecting member, wherein the end plate and the connecting member are fastened by a fastening member inserted in a direction orthogonal to the stacking direction. 8. The fuel cell according to claim 7, further comprising a plurality of the stacked batteries, wherein the stacked batteries are arranged in a direction orthogonal to an insertion direction of the fastening member. .