JP4706173B2 - Fuel cell stack - Google Patents

Description

  The present invention relates to a fuel cell stack configured by stacking a plurality of fuel cells, and more particularly, to a heat retention technique for an end cell of the fuel cell stack.

Conventionally, as described in Patent Document 1, for example, a fuel cell is used as a fuel cell stack configured by sandwiching a stack of a plurality of fuel cells between end plates. The end plate functions as a fixture that fixes the fuel cell with the fuel cell sandwiched therebetween, and includes a supply pipe for supplying hydrogen, air, and refrigerant from the outside to the fuel cell stack, as well as hydrogen and air used in the fuel cell stack. And a connecting tool for connecting a discharge pipe for discharging the refrigerant to the outside to the fuel cell stack.
JP 2000-90954 A Japanese Patent Laid-Open No. 7-282836

  By the way, the fuel cell has a suitable operating temperature range, and sufficient power generation performance cannot be obtained even at a temperature higher than this operating temperature range or at a lower temperature. Usually, the fuel cell is cooled by the refrigerant, so that the temperature rise due to reaction heat is suppressed, and the temperature is adjusted to an appropriate operating temperature. However, the fuel cell located on the outermost side of the fuel cell stack (hereinafter referred to as the end cell) is deprived of heat by heat dissipation from the adjacent end plate at low temperatures, and the temperature drops below the proper operating temperature. End up. Since the temperature decrease of the end cell causes a decrease in the power generation performance of the entire fuel cell stack, some contrivance is required to suppress the temperature decrease of the end cell due to heat radiation from the end plate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell stack capable of preventing a decrease in power generation performance by suppressing a temperature decrease in an end cell.

In order to achieve the above object, a first invention provides a fuel cell stack configured by laminating a plurality of fuel cells,
Air or refrigerant supplied to the fuel cell stack, or at least one flow path of hydrogen, air, or refrigerant discharged from the fuel cell stack is provided along the side surface of the end plate of the fuel cell stack ,
The flow path has a groove formed on a side surface of said end plate, characterized in that the cross section is composed of an arc-shaped lid.
The second aspect, in the first aspect, before Kiryuro is characterized by being formed of resin material.

The third invention is characterized in that, in any one of the first and second inventions , one or more fins are formed on the inner wall surface of the flow path on the end plate side.

According to a fourth invention , in any one of the first to third inventions , the flow path is a flow path of a liquid refrigerant discharged from the fuel cell stack.

According to the first and second inventions , the supply air, the supply refrigerant, the exhaust hydrogen, the exhaust air, and the exhaust refrigerant are high in temperature compared to the air temperature, so at least one of them is the end plate of the fuel cell stack. The end plate is warmed by flowing along the side surface of the end cell, thereby suppressing the temperature drop of the end cell at low temperatures.

According to the third aspect of the invention , the contact area with the fluid is increased by the fins, so heat transfer from the fluid to the end plate is promoted, and the temperature drop of the end cell is further suppressed.

According to the fourth invention , the temperature of the exhausted refrigerant is raised by the reaction heat in the fuel cell, and the liquid has a high heat exchange rate, so that the end plate can be warmed more effectively.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. The fuel cell stack of the present invention can be applied to, for example, a polymer electrolyte fuel cell mounted on a fuel cell vehicle. However, it is of course possible to apply to other types of fuel cells.

  FIG. 4 is a schematic diagram showing the overall configuration of the fuel cell stack 1. The fuel cell stack 1 is configured by stacking a plurality of fuel cells 6 in one direction and disposing end plates 2 and 4 at both ends in the stacking direction. Although not shown, the fuel cell 6 has a configuration in which a hydrogen ion permeable electrolyte membrane is sandwiched between an anode and a cathode, and both sides thereof are sandwiched between conductive separators. The end plates 2 and 4 at both ends are connected to each other by a fastening member (not shown) such as a tie rod so as to fasten and fix the stacked body of the fuel cells 6 from both sides. One end plate 2 also functions as a connecting member for connecting the two fuel cell stacks 1.

  In the fuel cell stack 1, an in-stack channel 8 through which fluids (hydrogen, air, and refrigerant) necessary for power generation in the fuel cell 6 circulate is provided. Although not shown in the figure, the in-stack channel 8 is provided separately for each of hydrogen, air, and refrigerant, and is sealed so that they do not mix. Hydrogen and air are used for power generation in each fuel cell 6, and the refrigerant is used to suppress temperature rise due to reaction heat during power generation. The in-stack channel 8 is formed in each fuel cell 6 and is provided with a supply channel 8a and a discharge channel 8c extending through both ends of the fuel cell 6 in the stacking direction of the fuel cell 6 and the supply channel 8a. And a cell channel 8b connecting the discharge channel 8c. The supply flow path 8a and the discharge flow path 8c are connected to an external flow path 10 provided outside the fuel cell stack 1 via the end plate 2, respectively. The fluid supplied from the out-of-stack channel 10 to the supply channel 8a is supplied from the supply channel 8a to the cell channel 8b of each fuel cell 6 and used for power generation and cooling while passing through the cell channel 8b. Thereafter, the gas is discharged from the discharge flow path 8 c to the out-stack flow path 10.

  The stack outer flow path 10 includes two types of a supply flow path 10 a for supplying fluid to the fuel cell stack 1 and a discharge flow path 10 b for discharging fluid from the fuel cell stack 1. Although not shown in the figure, these external stack channels 10 are also provided separately for each of hydrogen, air, and refrigerant. Conventionally, pipes for supplying and discharging fluid are connected substantially perpendicularly to the end plate 2 (see, for example, Patent Document 1). However, in the fuel cell stack 1 of the present embodiment, at least a part of the pipes are supplied. The out-stack channel 10 is provided along the side surface of the end plate 2.

  A basic configuration of a flow path outside the stack (hereinafter simply referred to as a flow path and referred to as a flow path outside the stack only when distinguished from the flow path 8 within the stack) 10 will be described with reference to FIGS. 1 and 2. 1 is a cross-sectional view in a direction perpendicular to the flow, and FIG. 2 is a cross-sectional view in the flow direction. As shown in the figure, a groove 20 is formed on the side surface of the end plate 2, and a lid 40 is attached to cover the groove 20. A plurality of fins 22 are provided in the groove 20 along the forming direction thereof. The lid 40 includes a volume portion 42 provided along the groove 20 and a flange portion 44 provided so as to surround the edge of the volume portion 42. The lid 40 is made of a material having a low thermal conductivity such as a resin (generally in a hydrogen supply pipe). The insulating material used may be used). The volume portion 42 bulges outward and is formed so that the cross-sectional shape in a direction perpendicular to the direction in which the groove 20 is formed is an arc. The lid 40 is fixed to the side surface of the end plate 2 with the flange portion 44 in close contact with the outer edge of the groove 20. By covering the groove 20 with the lid 40 in this way, a sealed space is formed between the groove 20 and the volume portion 42, and this space is the flow path 10. The flow path 10 and the in-stack flow path 8 are connected by a communication hole 24 formed through the end plate 2. A groove 48 is formed on the contact surface of the flange portion 44 with the end plate 2, and a sealing material 46 is embedded in the groove 48 in order to maintain the airtightness of the flow path 10. As the sealing material 46, liquid packing or adhesive may be used in addition to rubber packing.

  Since the flow path 10 is configured by the groove 20 and the lid 40 provided in the end plate 2, the fluid in the flow path 10 flows while contacting the end plate 2 along the side surface of the end plate 2. As a result, heat exchange occurs between the fluid flowing in the flow path 10 and the end plate 2. In the fuel cell stack 1, the supply air, the supply refrigerant, the exhaust hydrogen, the exhaust air, and the exhaust refrigerant are higher in temperature than the temperature, but when the flow path 10 is at least one of these, By the heat supply from the fluid, the temperature drop of the end plate 2 at the time of low temperature is suppressed, and the temperature decrease of the end cell 6a is suppressed. In particular, when the refrigerant is a liquid and the flow path 10 is the flow path of the discharged refrigerant, the discharged refrigerant is heated by the reaction heat in the fuel cell 6 and the liquid has a high heat exchange rate. Therefore, the end plate 2 can be warmed more effectively.

In addition, although the fins 22 are provided in the groove 20, the fins 22 increase the contact area between the end plate 2 and the fluid in the flow path 10. Thereby, the heat transfer from the fluid to the end plate is promoted, and a great effect is obtained in suppressing the temperature drop of the end plate 2. Further, the lid 20 is formed in an arc shape in cross section so that the surface area with respect to the volume is reduced, and heat radiation from the lid 40 to the outside air is suppressed. Therefore, according to the configuration of the flow path 10 according to the present embodiment, the heat of the fluid flowing in the flow path 10 can be efficiently transmitted to the end plate 2. In addition, since the heat radiation to the outside air is suppressed, the temperature drop of the fluid itself flowing in the flow path 10 can also be suppressed, and dew condensation in the flow path 10 can be prevented if the fluid contains water. .

  Next, a specific application example of the flow path 10 according to the present embodiment will be described with reference to FIG. FIG. 3 is a side view of the end plate 2 according to the present embodiment, and corresponds to a view seen from the direction A in FIG. As shown in the figure, three communication holes 24a, 24b, 24c are formed in a row at the same interval at both ends of the end plate 2, and three communication holes 24d, 24e, 24f are formed at the same interval in the middle. Formed in a row. Among these, the communication holes 24 a, 24 b, 24 c, 24 d, 24 e are through holes that penetrate the end plate 2. The communication holes 24a, 24b, 24c formed at the end of the end plate 2 are holes that communicate with the supply flow path 8a (see FIG. 1) in the fuel cell stack 1, and the communication holes 24d, 24e formed at the center. , 24f are holes communicating with the discharge flow path 8c (see FIG. 1) in the fuel cell stack 1. Here, the communication hole 24a is a hydrogen supply hole, the communication hole 24b is an air supply hole, the communication hole 24c is a refrigerant supply hole, the communication hole 24d is a refrigerant discharge hole, the communication hole 24e is an air discharge hole, and the communication hole 24f is a hydrogen discharge hole. It is.

  Between the left and right hydrogen supply holes 24a, between the air supply holes 24b, between the refrigerant supply holes 24c, between the refrigerant discharge holes 24d, and between the air discharge holes 24e, the left and right holes are connected on the side surface of the end plate 2. A groove (not shown) is formed along the side surface of each end plate 2. Lids 50, 60a, 60b, 70, 80 are fixed to the side surfaces of the end plate 2 by bosses so as to cover the respective grooves. By covering the groove with the lids 50, 60a, 60b, 70, 80 in this way, an air supply channel 10B is formed under the lid 60a, and an air discharge channel 10E is formed under the lid 60b. Has been. A refrigerant supply flow path 10C is formed under the lid 70, a refrigerant discharge flow path 10D is formed under the cover 80, and a hydrogen supply flow path 10A is formed under the cover 50. Yes.

  The lids 50, 60a, 70 are provided with supply ports 52, 62, 72 for supplying fluid to the supply channels 10A, 10B, 10C, and the lids 60b, 80 have fluid discharge channels 10D, 10E. Discharge ports 64 and 82 are provided for discharging from the air. The supply channels 10A, 10B, and 10C distribute the fluid supplied from the supply ports 52, 62, and 72 to the supply holes 24a, 24b, and 24c, and the discharge channels 10D and 10E are discharged from the discharge holes 24d and 24e. The collected fluid is collected at the discharge ports 64 and 82.

  The configuration of the lid 40 shown in FIGS. 1 and 2 is applied to each lid 50, 60 a, 60 b, 70, 80. However, the lids 60a and 60b of the adjacent air supply flow path 10B and air discharge flow path 10E are integrally molded to form one cover 60, and the air supply flow path 10B and the air discharge flow path 10E are separated. A sealing material (not shown) is shared between the two lids 60a and 60b. In this way, if the fluids are of the same type, it is possible to integrate the lid and share the seal material by adjoining the flow paths, and the number of parts can be reduced.

  The configuration of the flow path 10 shown in FIGS. 1 and 2 is applied as it is to the air supply flow path 10B, the air discharge flow path 10E, the refrigerant supply flow path 10C, and the refrigerant discharge flow path 10D. These flow paths 10B, 10C, 10D, and 10E are provided along the side surface of the end plate 2, and fins for promoting heat transfer are provided on the wall surfaces of the internal grooves. Since the supply air, the supply refrigerant, the supply air, and the supply refrigerant are higher in temperature than the air temperature, the end plate 2 is warmed by flowing along the side surfaces of the end plate 2. Thereby, even at the time of low temperature, the temperature fall of the fuel cell 6, especially the end cell 6a located in the outermost side is suppressed.

  On the other hand, the hydrogen supply channel 10A has a different configuration from the other channels 10B, 10C, 10D, and 10E. Although the hydrogen supply channel 10A is common in that it is provided along the side surface of the end plate 2, no fin is provided on the wall surface of the internal groove. This is because heat transfer from the end plate 2 is suppressed to keep the end cell warm, and condensation in the end cell is prevented. The configuration of the air supply channel 10B described above assumes that the supply air is dry air. However, when the supply air is humidified air containing moisture, the hydrogen supply channel 10A is used to prevent condensation. The fins may be eliminated in the same manner as.

  While the flow paths 10A, 10B, 10C, 10D, and 10E are provided outside the end plate 2, only the hydrogen discharge flow path 10F is formed inside the end plate 2. The hydrogen discharge hole 24f is opened from the side surface of the fuel cell 6 of the end plate 2 to the center of the end plate 2, and a hydrogen discharge flow path 10F is formed so as to connect the left and right hydrogen discharge holes 24f. A discharge port 92 for discharging hydrogen from the hydrogen discharge channel 10 </ b> F to the outside is formed on the bottom surface of the end plate 2. Thus, by providing the hydrogen discharge flow path 10 </ b> F inside the end plate 2, the heat of discharged hydrogen is efficiently transmitted to the end plate 2, and a discharge port 92 is formed on the bottom surface of the end plate 2. This improves the drainage of the water generated inside the fuel cell stack 1.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the end plate 2 and the lids 40, 50, 60a, 60b, 70, 80 may be made of the same weldable resin. According to this, fixing and sealing can be realized simultaneously by welding, and it becomes possible to reduce the sealing material and the mounting boss.

  In the embodiment, the hydrogen discharge flow path 10F is formed inside the end plate 2. However, as with other fluids, the discharge hydrogen flow path is set so that the discharged hydrogen flows along the side surface of the end plate 2. It may be formed. Further, the hydrogen supply channel 10 </ b> A through which relatively low-temperature supply hydrogen flows may be provided away from the end plate 2. The arrangement and configuration of the flow paths shown in FIG. 3 are merely examples for embodying the present invention, and at least one flow path among the supply air, supply refrigerant, exhaust hydrogen, exhaust air, and exhaust refrigerant is the end plate 2. It suffices to be provided along the side surface.

It is sectional drawing which shows the basic composition of the flow path concerning embodiment of this invention. It is sectional drawing which shows the basic composition of the flow path concerning embodiment of this invention. It is a side view of the end plate concerning an embodiment of the invention. 1 is a schematic diagram showing an overall configuration of a fuel cell stack as an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2, 4 End plate 6 Fuel cell 8 Flow path (flow path in stack)
10 Flow path (flow path outside stack)
10A Hydrogen supply flow path 10B Air supply flow path 10C Refrigerant supply flow path 10D Refrigerant discharge flow path 10E Air discharge flow path 10F Hydrogen discharge flow path 20 Groove 22 Fin 24 Communication holes 40, 50, 60a, 60b, 70, 80 Lid 46 Sealing material 52, hydrogen supply port 62, air supply port 72, refrigerant supply port 82, refrigerant discharge port 64, air discharge port 92, hydrogen discharge port

Claims (4)

In a fuel cell stack configured by stacking a plurality of fuel cells,
Air or refrigerant supplied to the fuel cell stack, or at least one flow path of hydrogen, air, or refrigerant discharged from the fuel cell stack is provided along the side surface of the end plate of the fuel cell stack ,
The fuel cell stack characterized in that the flow path is constituted by a groove formed on a side surface of the end plate and a lid having a circular cross section . The fuel cell stack according to claim 1, wherein the flow path is formed of a resin material. The fuel cell stack according to claim 1 or 2, wherein one or a plurality of fins are formed on an inner wall surface of the flow path on the end plate side. The fuel cell stack according to any one of claims 1 to 3, wherein the flow path is a flow path of a liquid refrigerant discharged from the fuel cell stack.

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