JP2005285682A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably heat cells at both ends and stably operate a fuel cell. <P>SOLUTION: The solid polymer fuel cell stack 10 is constituted so that cooling water used for cooling a cell 20 and cooling water flowing through a cooling water draining manifold 44 are made to flow in a stack end part passage installed in an almost continuous S shape in accordance with a high temperature region of the cell 20 in an upper region of an end plate 70 and an end plate 80. Cooling water flowing from the cell 20 at the end part of the stack into the cooling water draining manifold 44 is kept at prescribed temperature with a flow rate control element 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell stack. More specifically, the present invention relates to a fuel cell stack in which the cell temperature is optimized.

  Generally, a polymer electrolyte fuel cell stack comprises a membrane electrode assembly (hereinafter referred to as “MEA”) by joining an anode to one surface of a solid polymer membrane and a cathode to the other surface. A cell is constituted by sandwiching an anode side plate provided with a fuel flow path facing the anode of the MEA and a cathode side plate provided with an oxidant flow path facing the cathode of the MEA. A laminate is formed by laminating a plurality of layers with a cooling plate interposed therebetween, and end plates are attached to both ends of the laminate and tightened.

  In the polymer electrolyte fuel cell stack, fuel gas such as reformed gas is circulated through the anode side plate, and oxidant gas such as air is circulated through the cathode side plate to cause an electrochemical reaction through the electrolyte membrane. To generate DC power. Since the electrochemical reaction is an exothermic reaction, the normal operating temperature of the polymer electrolyte fuel cell stack (for example, about 70 to 80 [° C.]) is obtained by circulating cooling water through the cooling plate to cool each cell. Is maintained.

  In the polymer electrolyte fuel cell stack, the cells at both ends adjacent to the end plate are easily affected by outside air. For this reason, the temperature of the cells at both ends is lower than that of the other cells. When the temperature of the cell decreases, water vapor in the reaction gas flowing through the flow path of the anode side plate or the cathode side plate condenses in the flow path. Condensed water formed by condensing water vapor obstructs the flow of the reaction gas and causes deterioration in battery performance.

In view of such a current situation, a technology for suppressing a temperature drop of cells at both ends in a polymer electrolyte fuel cell stack is desired. As this type of technology, for example, a flow path for flowing cooling water is provided on the end plates at both ends, the temperature is raised to a temperature close to the operating temperature, and cooling water discharged after power generation is provided over the entire end plate. A technique for heating a cell at both ends by flowing in a flow path is known (for example, Patent Document 1).
JP 2001-68141 A

  Generally, the temperature distribution of the cell is caused by the flow of cooling water inside the cooling plate. That is, the cooling water just supplied to the cooling plate cools the cell efficiently, but the temperature of the cooling water rises as it flows through the cooling plate, and the cooling effect of the cell is diminished. For this reason, a temperature gradient is generated in the cell along the flow direction of the cooling water. The “cooling water flow direction” refers to the direction from the inlet to the outlet of the cooling water channel, not the direction itself along the path of the cooling water channel provided in the cooling plate.

  However, if the cooling water discharged after power generation is caused to flow through the flow path provided on the entire end plate as in the prior art, the cells at both ends are evenly heated. As a result, there is a difference in temperature distribution between the cells at both ends and the cells at other portions, and the portions where condensed water is generated are different between the cells at both ends and the other portions. The voltage generated by the battery becomes unstable, and it becomes difficult to stably operate the polymer electrolyte fuel cell.

  The present invention has been made in view of such problems, and an object thereof is to provide a fuel cell stack capable of appropriately heating cells at both ends in order to stably operate the fuel cell.

  An aspect of the fuel cell stack of the present invention includes a membrane electrode assembly having an electrolyte membrane, an anode provided on one surface of the electrolyte membrane, and a cathode provided on the other surface of the electrolyte membrane, and the anode Cooling provided with a cell having an anode side plate having a fuel flow path facing the cathode, a cathode side plate having an oxidant flow path facing the cathode, and a heat medium flow path through which the heat medium for cooling the cell flows A fuel cell stack comprising: a laminated body in which a plurality of plates are laminated; and end plates that are provided at both ends of the laminated body via current collector plates and insulating plates and fasten the laminated body, wherein the cooling plate is A stack end flow path through which the passed heat medium flows is provided in a part of the end plate, and the stack end flow path is located in a region corresponding to a high temperature region of the cell. .

  According to this, since the high temperature part of the cells at both ends of the stack is appropriately heated according to the temperature distribution of the cells at the other part, the high temperature part of the cells at both ends of the stack is the temperature distribution of the cells at the other part. And approximate. As a result, the amount of condensed water generated in the cells at both ends of the stack is reduced, and the clogging of the reaction gas flow paths in the cells is suppressed. Variation of the voltage generated in the above is suppressed, and the fuel cell can be operated stably. Water is suitable as the heat medium, but other fluids of water can be used.

  The said aspect WHEREIN: You may have a 1st flow control element which controls the flow volume of the said heat medium which flows in into the said stack edge part flow path according to the temperature of the said heat medium. As a result, even if the output of the fuel cell stack fluctuates, the temperature gradient of the cells at both ends can be kept constant by adjusting the temperature of the heat medium flowing through the stack end channel. The operational stability of the fuel cell stack can be improved.

In the above aspect, the flow rate of the heat medium that passes through the cooling plate provided at the end of the laminated body while flowing into the cooling water discharge manifold penetrating the laminated body and communicating with the stack end flow path. May be provided according to the temperature of the heat medium that has passed through the cooling plate. According to this, even when the output of the fuel cell stack fluctuates, the temperature gradient of the cells at both ends is kept constant by adjusting the temperature of the heat medium passing through the cooling plate at the end of the stack. Therefore, the operational stability of the fuel cell stack can be improved.
Further, in the above aspect, the heat transfer amount in the flow direction of the heat medium flowing through the heat medium flow channel in the remaining part of the end plate where the stack end flow channel is not provided flows through the heat medium flow channel. It may be smaller than the heat transfer amount in the direction perpendicular to the flow direction of the heat medium. According to this, the high temperature region of the cell at the stack end is heated by the heat medium flowing through the stack end flow path, and the temperature distribution of the cell is also applied to the end plate portion where the stack end flow path is not provided. Accordingly, the temperature distribution of the cells at the stack end can be made closer to the temperature distribution of the cells at other portions. Note that “the flow direction of the heat medium” refers not to the direction along the path of the heat medium flow path provided in the cooling plate but to the direction from the inlet of the heat medium flow path to the outlet.

  Furthermore, in the above aspect, each of the fuel flow path, the oxidant flow path, and the heat medium flow path is configured by a plurality of linear flow paths, and flows through the fuel flow path and the oxidant flow path. The oxidant may form a parallel flow that flows downward from above, and the heat medium that flows through the heat medium flow path may form a parallel flow or a counterflow with respect to the fuel and the oxidant. When the fuel flow path, the oxidant flow path, and the heat medium flow path meander, a partially irregular temperature distribution occurs, but according to the above configuration, the continuous temperature distribution along each flow path Therefore, the stability of the fuel cell stack can be improved.

  A combination of the above-described elements as appropriate can also be included in the scope of the invention for which patent protection is sought by this patent application.

  According to the apparatus of the present invention, the fuel cell can be stably operated.

(Example 1)
FIG. 1 is a schematic diagram illustrating a configuration of a polymer electrolyte fuel cell stack 10 according to a first embodiment. The polymer electrolyte fuel cell stack 10 includes a stacked body 40 in which a plurality of cells 20 and a cooling plate 30 interposed between the cells 20 are stacked, and a current collector plate 50 and an insulating plate 60 from both ends of the stacked body 40. End plates 70 and 80 for fastening the laminate 40 are provided.

  The cell 20 includes an MEA 22, an anode side plate 24 provided with a fuel flow path facing the anode of the MEA 22, and a cathode side plate 26 provided with an oxidant flow path facing the cathode of the MEA 22.

  The cooling plate 30 has a cooling water passage 32 through which cooling water used as a heat medium flows. Near the outlet of the cooling water channel 32 of the cooling plate 30 located at both ends of the stacked body 40, a flow rate control element 34 for adjusting the flow rate of cooling water flowing from the cooling water channel 32 into a cooling water discharge manifold 44 described later is provided. It has been. The flow control element 34 will be described later.

  The cooling water flow path 32 can also be provided on the opposite side of the anode side plate 24 and / or the cathode side plate 26 from the MEA 22. In this case, the anode side plate 24 and / or the cathode side plate 26 also serves as the cooling plate 30. Further, the present invention includes a case where a so-called bipolar plate in which a fuel channel is provided on one surface of one plate and an oxidant channel is provided on the other surface is partially used.

  A cooling water supply manifold 42 that communicates in the stacking direction of the cells 20 is provided below the stacked body 40. In addition, a cooling water discharge manifold 44 that communicates in the stacking direction of the cells 20 is provided on the upper portion of the stacked body 40.

  FIG. 2 is a schematic diagram showing the configuration of the end plate 70. The end plate 70 includes a cooling water supply port 71, a stack end channel 72, a flow rate control element 73, a cooling water discharge port 74, a cooling water inlet 75, a fuel inlet 76, a fuel outlet 77, an oxidant inlet 78, and an oxidant outlet. 79.

  The cooling water supply port 71 communicates with the cooling water discharge manifold 44, and is cooled to a temperature close to the operating temperature from the cooling water discharge manifold 44 to the stack end channel 72 via the cooling water supply port 71. Water flows in. The stack end flow path 72 is formed in a tunnel shape by attaching the closing plate 81 on the concave groove shape provided in the end plate 70. The closing plate 81 is preferably formed of a material having good thermal conductivity. The stack end channel 72 is formed in a substantially continuous S-shaped path in the upper region of the end plate 70 corresponding to the high temperature region of the cell 20.

  The flow rate control element 73 is provided in the vicinity of the cooling water discharge port 74 of the stack end channel 72, and adjusts the flow rate of the cooling water flowing into the stack end channel 72, thereby cooling the cooling water in the stack end channel 72. The water temperature is maintained at a predetermined temperature. The flow rate control element 73 is composed of, for example, a temperature-sensitive flow rate control element that is deformed according to the temperature of the cooling water after flowing through the stack end flow path 72 and exchanging heat, and in the stack end flow path 72 It has the function of a valve that opens and closes according to the temperature of the cooling water. Specific examples of the temperature-sensitive flow rate control element include bimetal, shape memory alloy, and thermoloid. In addition to using a temperature-sensitive flow rate control element, a temperature sensor for detecting the temperature of the cooling water, the temperature of the end plate 70, or the temperature of the cell 20 at both ends, and a valve capable of controlling the opening and closing drive are provided. The opening / closing of the valve may be controlled in accordance with the coolant temperature in the stack end flow path 72 detected in (1). In this case, the position of the valve may be near the stack end channel 72.

  3A shows a configuration in the case where a bimetal is used for the flow rate control element 73, and FIG. 3B shows a cross-sectional view along the line AA in FIG. 3A. The flow rate control element 73 senses the temperature of the cooling water after flowing through the stack end channel 72 and exchanging heat, and adjusts the flow rate of the cooling water flowing in the stack end channel 72. Specifically, the flow rate control element 73 is in a reference state in which a predetermined flow rate flows when the temperature of the cooling water is a predetermined temperature, but when the temperature of the cooling water is equal to or higher than the predetermined temperature, The state is deformed from the state in the direction of arrow H in FIG. 3B, and the cross-sectional area of the stack end channel 72 is reduced to reduce the flow rate of the cooling water flowing through the stack end channel 72. When the temperature of the cooling water is equal to or lower than a predetermined temperature, the cooling water is deformed from the reference state in the direction of arrow L in FIG. 3B, and the cross-sectional area of the stack end channel 72 is increased to increase the stack end flow. The flow rate of the cooling water flowing through the path 72 is increased.

  According to this, when the output of the polymer electrolyte fuel cell stack 10 fluctuates and the temperature of the cell 20 fluctuates, the temperature of the cooling water in the stack end channel 72 is kept constant, thereby Therefore, the temperature distribution of the cells 20 in the part can be kept constant, and the operation of the polymer electrolyte fuel cell stack 10 can be stabilized.

  The cooling water discharge port 74 communicates with the outlet portion of the stack end flow path 72 and discharges the cooling water flowing through the stack end flow path 72. The cooling water inlet 75 communicates with the cooling water supply manifold 42. The fuel inlet 76, fuel outlet 77, oxidant inlet 78 and oxidant outlet 79 will be described later.

  The cooling water supply port 71 communicates with the outside of the polymer electrolyte fuel cell stack 10 and can discharge excess cooling water that does not flow into the stack end channel 72.

  The basic configuration of the other end plate 80 is the same as that of the end plate 70, but the cooling water inlet 75, the fuel inlet 76, the fuel outlet 77, the oxidant inlet 78, and the oxidant outlet 79 are not provided.

(Reactive gas flow)
A fuel gas such as a reformed gas is supplied from the fuel inlet 76 and passes through a fuel supply manifold (not shown) provided in communication with the polymer electrolyte fuel cell stack 10 in the stacking direction. To be distributed. The fuel gas supplied to each cell 20 flows through the fuel flow path. On the other hand, an oxidant gas such as air is supplied from an oxidant inlet 78 and passes through an oxidant gas supply manifold (not shown) provided in communication with the solid polymer fuel cell stack 10 in the stacking direction. , Distributed to each cell 20. The oxidant gas supplied to each cell 20 flows through the oxidant flow path.

  In each cell 20 in which the fuel gas and the oxidant gas circulate, electric power is generated by an electrochemical reaction through the electrolyte membrane. Unreacted fuel gas discharged from each cell 20 joins at a fuel discharge manifold (not shown) provided in communication with the polymer electrolyte fuel cell stack 10 in the stacking direction, and passes through the fuel discharge manifold. The fuel is discharged from the fuel outlet 77 to the outside. In general, the unreacted fuel gas discharged from the fuel outlet 77 is introduced into a reformer burner of a fuel reformer (not shown) and burned.

  The unreacted oxidant gas discharged from each cell 20 after power generation is merged by an oxidant discharge manifold (not shown) provided in communication with the stacking direction of the polymer electrolyte fuel cell stack 10 to be oxidant. It is discharged from the oxidant outlet 79 through the discharge manifold.

(Cooling water flow)
The cooling water is supplied from the cooling water inlet 75 and distributed and supplied to each cooling water flow path 32 through the cooling water supply manifold 42 provided in communication with the stacking direction of the polymer electrolyte fuel cell stack 10. The cooling water flowing through each cooling water flow path 32 cools each cell 20 to maintain each cell 20 at an appropriate operating temperature (for example, about 70 to 80 [° C.]).

  The cooling water discharged from the cooling water flow path 32 is heated by the reaction heat generated in each cell 20 to a temperature of about 72 to 75 [° C.]. The cooling water whose temperature has risen flows into the cooling water discharge manifold 44. A partition (not shown) is provided in the vicinity of the central portion in the stacking direction of the polymer electrolyte fuel cell stack 10 of the cooling water discharge manifold 44, and the cooling water heated up at the partition is divided into two directions. Also good.

  The flow rate control element 34 provided in the vicinity of the outlet of the cooling water flow path 32 located at both ends of the laminate 40 has the same basic configuration as the flow rate control element 73 provided on the end plate 70. However, the flow rate control element 34 is in a reference state in which a predetermined flow rate flows when the temperature of the cooling water flowing through the cooling water flow channel 32 located at the end is a predetermined temperature. When the temperature of the cooling water is equal to or higher than a predetermined temperature, the flow rate of the cooling water flowing through the end cooling water passage 32 is increased by increasing the cross-sectional area of the end cooling water passage 32. When the temperature of the cooling water is equal to or lower than a predetermined temperature, the flow rate of the cooling water flowing through the cooling water flow path 32 at the end is reduced by reducing the cross-sectional area of the cooling water flow path 32 at the end.

  According to this, when the output of the polymer electrolyte fuel cell stack 10 fluctuates and the temperature of the cell 20 fluctuates, by keeping the cooling water temperature in the cooling water flow path 32 at the end constant, The temperature distribution of the cells 20 at both ends can be kept constant, and the operation of the polymer electrolyte fuel cell stack 10 can be stabilized.

  Cooling water flowing through the cooling water discharge manifold 44 toward the end plate 70 flows into the stack end flow path 72 from the cooling water supply port 71 of the end plate 70, and from the upper portion of the end plate 70 to the lower portion. It flows while meandering. Heating the cell 20 at the end adjacent to the end plate 70 through the closing plate 81, the current collector plate 50, and the insulating plate 60 by the flow of the heated cooling water in the stack end channel 72 Can do. In addition, the stack end channel 72 has a path in the upper region of the end plate 70 corresponding to the high temperature region of the cell 20, and the cooling water flowing through the stack end channel 72 is the stack end channel 72. The temperature gradually decreases as it goes downstream. For this reason, while the high temperature area | region of the cell 20 of the edge part on the end plate 70 side is heated efficiently, the temperature distribution of the cell 20 of the edge part on the side of the end plate 70 and the cell 20 of another part can be approximated.

  On the other hand, the cooling water flowing through the cooling water discharge manifold 44 toward the end plate 80 flows from the cooling water supply port 71 of the end plate 70 into the stack end flow path 72 and downward from the upper portion of the end plate 70. It flows while meandering towards the club. Heating the cell 20 at the end adjacent to the end plate 80 through the closing plate 81, the current collector plate 50, and the insulating plate 60 by the flow of the heated coolant in the stack end channel 72. Can do. Moreover, the stack end channel 72 has a path in the upper region of the end plate 80 corresponding to the high temperature region of the cell 20, and the cooling water flowing through the stack end channel 72 is the stack end channel 72. The temperature gradually decreases as it goes downstream. For this reason, while the high temperature area | region of the cell 20 of the edge part on the end plate 80 side is heated efficiently, the temperature distribution of the cell 20 of the edge part on the side of the end plate 80 and the cell 20 of another part can be approximated.

  As a result of heating the high temperature region of the cells 20 at both ends, the amount of condensed water generated in the cells 20 at both ends is reduced, and the temperature distribution of the cells 20 at both ends is the temperature distribution of the cells 20 at other portions. Therefore, the locations where the condensed water is generated in each cell 20 are almost the same, and the power generation efficiency of each cell 20 can be improved evenly.

  From the viewpoint of optimizing the temperature distribution of each cell 20 when the polymer electrolyte fuel cell stack 10 is operated, the fuel flow path, the oxidant flow path, and the cooling water flow path 32 each include a plurality of linear flow paths. The fuel gas flowing through the fuel flow channel and the oxidant gas flowing through the oxidant flow channel are parallel flows that flow downward from above, and the cooling water flowing through the cooling water flow channel 32 is in parallel with the fuel gas and the oxidant gas. Preferably, the cooling water flowing in the cooling water flow path 32 is opposed to the fuel gas and the oxidant gas, that is, it is more preferable that the cooling water flows from below to above. According to this, since a continuous temperature distribution along the flow path is formed, the stability of the polymer electrolyte fuel cell stack 10 can be improved.

(Comparative Example 1)
FIG. 4 shows a polymer electrolyte fuel cell stack 10A according to Comparative Example 1 configured for comparison with Example 1 described above. Since the basic configuration of the polymer electrolyte fuel cell stack 10A is the same as that of the polymer electrolyte fuel cell stack 10 of the first embodiment, the same members are denoted by the same reference numerals and detailed description thereof is omitted. In the polymer electrolyte fuel cell stack 10A, the flow rate control element 34 is not provided in the cooling water flow path 32 at both ends, and the form of the water flow path provided in the end plates 70A and 80A is different from that of the first embodiment. To do. That is, since the end plate 70A and the end plate 80A have substantially the same configuration, the end plate 70A will be described. As shown in FIG. 5, the stack end channel 72A has a substantially continuous S-shape over almost the entire surface of the end plate 70A. Comparative Example 1 is the first embodiment in that the flow rate control element 73 is not provided and all the cooling water supplied from the cooling water supply port 71 flows into the stack end channel 72A. And different.

  In Comparative Example 1, the cooling water after the temperature rise discharged from each cell 20 after power generation flows through the cooling water discharge manifold 44A and then flows into the stack end flow path 72A, from the upper part toward the lower part. The water flows while meandering and is discharged to the outside from a cooling water discharge port 74A provided at the lower end.

  In Comparative Example 1, the stack end channel 72A is provided over almost the entire surface of the end plate 70A, and all the cooling water supplied from the cooling water supply port 71 flows into the stack end channel 72A without limitation. Therefore, the temperature distribution in the end plate 70A does not occur and the temperature is constant, and when the output of the polymer electrolyte fuel cell stack varies, the temperature of the end plate 70A varies accordingly.

(Comparative Example 2)
FIG. 6 shows a polymer electrolyte fuel cell stack 10B according to Comparative Example 2 configured for comparison with Example 1 described above. Since the basic configuration of the polymer electrolyte fuel cell stack 10B is the same as that of the polymer electrolyte fuel cell stack 10 of the first embodiment, the same members are denoted by the same reference numerals and detailed description thereof is omitted. The end plates 70B and 80B of the polymer electrolyte fuel cell stack 10B are significantly different from the polymer electrolyte fuel cell stack 10 of Example 1 in that they do not have a water channel. However, a cooling water discharge port 74B communicating with the cooling water discharge manifold 44 is provided in the end plate 70B.

  In the comparative example 2, the heated cooling water discharged from each cell 20 after power generation passes through the cooling water discharge manifold 44 and is drained to the outside from the cooling water discharge port 74B of the end plate 70B. Therefore, heating of the cells 20 at both ends using the cooling water after the temperature rise is not performed.

(Evaluation of Examples and Comparative Examples)
Three types of polymer electrolyte fuel cell stacks (65 cells) of Example 1, Comparative Example 1 and Comparative Example 2 were produced, and a temperature distribution measurement experiment of each cell during power generation was performed. FIG. 7 shows the experimental results of cell temperature distribution measurement. The temperature of each cell was measured at the cell bottom, cell center and cell top. As shown in FIG. 7, in Example 1, the temperature T10 at the bottom of the cell, the temperature T12 at the center of the cell, and the temperature T14 at the top of the cell are not different from each other cell and other cells. It was confirmed that the temperature distribution was very close.

  On the other hand, in Comparative Example 2, the temperature T20 at the bottom of the cell, the temperature T22 at the center of the cell, and the temperature T24 at the top of the cell are lower than the other cells in both end cells. The temperature drop in both end cells of T24 was significant.

  In Comparative Example 1, the temperature drop at both end cells is improved compared to Comparative Example 2 in terms of temperature T30, cell center temperature T32, and cell topmost temperature T34, but both end cells and other portions of the cell are not. It was confirmed that the temperature distribution was still different.

  From the above experimental results, in the polymer electrolyte fuel cell stack of Example 1, the temperature-controlled cooling water was applied to part of the end plate 70 and the end plate 80 corresponding to the high temperature region of the cell. It was found that the temperature distribution of each cell can be approximated by flowing.

  In addition, the path | route of the stack edge part flow path 72 in the end plates 70 and 80 of a polymer electrolyte fuel cell stack is not restricted to the form of Example 1. FIG. Example 2 and Example 3 described below have the same basic configuration as Example 1 except that the configuration of the stack end flow path 72 of the end plates 70 and 80 is the same. A detailed description is omitted with reference numerals.

(Example 2)
FIG. 8 is a schematic diagram illustrating a configuration of an end plate 70C of the polymer electrolyte fuel cell stack according to the second embodiment. The stack end channel 72C in the end plate 70C of the second embodiment is common to the first embodiment in that it is provided in a substantially continuous S shape in the upper region of the end plate 70C corresponding to the high temperature region of the cell 20. . However, the stack end flow path 72C of the second embodiment has a larger cross-sectional area as it is located above the end plate 70C. As a result, the upper part of the cell 20 at the stack end is more effectively heated by the cooling water flowing through the stack end channel 72C, so that the temperature distribution of the cell 20 at the stack end can It can be closer to the temperature distribution.

(Example 3)
FIG. 9 is a schematic diagram illustrating a configuration of an end plate 70D of the polymer electrolyte fuel cell stack according to the third embodiment. The stack end channel 72D in the end plate 70D of the third embodiment is common to the first embodiment in that it is provided in a substantially continuous S shape in the upper region of the end plate 70D corresponding to the high temperature region of the cell 20. . However, as the stack end portion flow path 72D of the third embodiment is positioned above the end plate 70D, the interval between the folded paths is closer. As a result, the upper part of the cell 20 at the stack end is more effectively heated by the cooling water flowing through the stack end channel 72C, so that the temperature distribution of the cell 20 at the stack end can It can be closer to the temperature distribution.

  In addition, although the stack edge part flow path shown in Example 1-3 is formed in the end plates 70 and 80, it may be formed not only in the end plates 70 and 80 but in the current collecting plate 50 or the insulating plate 60. In addition, the end plates 70 and 80 may be formed so as to also serve as the insulating plate 60. For example, it is possible to form a stack end flow path by forming grooves in both of the end plates 70 and 80 and the insulating plate 60 and bonding the end plates 70 and 80 and the insulating plate 60 together.

  Example 1-3 demonstrated above is a form which gives moderate temperature distribution to the cell of a stack | stuck edge part using the cooling water which temperature rose with the reaction heat of the cell. Next, a configuration for optimizing the temperature distribution of the cells at both ends of the stack in a form different from that of Example 1-3 will be described.

Example 4
FIG. 10 shows a configuration of a polymer electrolyte fuel cell stack 10E according to the fourth embodiment. The basic configuration of the polymer electrolyte fuel cell stack 10E is the same as that of the polymer electrolyte fuel cell stack 10 of the first embodiment. Since the end plate 70E and the end plate 80E have substantially the same configuration, the end plate 70E will be described below. However, the polymer electrolyte fuel cell stack 10E is provided with a cooling water discharge port 74E communicating with the cooling water discharge manifold 44 in the end plate 70E.

  FIG. 11 is a schematic diagram illustrating a configuration of an end plate 70E of the polymer electrolyte fuel cell stack according to the fourth embodiment. The end plate 70E is provided with a plurality of cuts 90 in a direction perpendicular to the direction of the flow of the cooling water in the cell 20 indicated by the arrow T.

  The notch 90 inhibits heat conduction in the direction of arrow T of the end plate 70E, and the amount of heat transfer in the direction of the cooling water flow in the cell 20 is perpendicular to the direction of the cooling water flow in the cell 20. Lower than the amount of transmission. For this reason, a temperature difference is maintained between the upper part and the lower part of the end plate 70E, and the temperature drop of the upper part of the cell 20 adjacent to the end plate 70E via the current collecting plate 50 and the insulating plate 60 is suppressed, and the stack end The temperature distribution of the part cell 20 is approximate to the temperature distribution of the other part cell 20.

  In the fourth embodiment, a plurality of cuts 90 are made from one side in the lateral direction of the end plate 70E. However, a plurality of cuts 90 may be made alternately from both sides in the lateral direction of the end plate 70E. .

  In addition, the form which makes the heat transfer amount of the end plate 70E of the polymer electrolyte fuel cell stack different in the direction of the flow of the cooling water and the vertical direction thereof is not limited to the configuration of the fourth embodiment. Example 5 and Example 6 described below are the same in basic configuration as Example 4 except that the configurations of the end plates 70E and 80E are different. Is omitted.

(Example 5)
FIG. 12 shows the configuration of the end plate 70F of the polymer electrolyte fuel cell stack according to the fifth embodiment. The end plate 70F is provided with a plurality of holes 92 along the direction of the flow of the cooling water in the cooling water flow path 32 indicated by the arrow T. As for the shape of the hole 92, it is desirable that the longitudinal direction is perpendicular to the direction of the cooling water flow.

  The hole 92 inhibits heat conduction in the direction of the arrow T of the end plate 70F, and the amount of heat transfer in the direction of the flow of the reaction gas in the cell 20 is perpendicular to the direction of the flow of the cooling water in the cooling water channel 32. The amount of heat transfer is low. For this reason, the temperature difference is maintained between the upper part and the lower part of the end plate 70F, and the temperature drop of the upper part of the cell 20 adjacent to the end plate 70F via the current collector plate 50 and the insulating plate 60 is suppressed, and the stack end The temperature distribution of the part cell 20 is approximate to the temperature distribution of the other part cell 20.

(Example 6)
FIG. 13 shows a configuration of an end plate 70G of the polymer electrolyte fuel cell stack according to the sixth embodiment. The end plate 70G is divided into a plurality of parts with respect to the flow direction of the cooling water in the cooling water flow path 32 indicated by the arrow T. As a result of the end plate 70G being divided into a plurality of directions with respect to the flow direction of the cooling water, the heat conduction between the divided end plates 70G is remarkably hindered, and the direction of the flow of cooling water in the cooling water passage 32 The heat transfer amount is lower than the heat transfer amount in the direction perpendicular to the flow direction of the cooling water in the cooling water flow path 32. For this reason, the temperature difference between the upper part and the lower part of the end plate 70G is maintained, and the temperature drop of the upper part of the cell 20 adjacent to the end plate 70G via the current collecting plate 50 and the insulating plate 60 is suppressed, and the stack end The temperature distribution of the part cell 20 is approximate to the temperature distribution of the other part cell 20.

  When the end plate 70G is divided into a plurality of portions, the entire polymer electrolyte fuel cell stack is tightened with a rod or the like for each divided portion of the end plate 70G.

  The plate shape of the end plate shown in Example 4-6 is applicable not only to the end plates 70 and 80 but also to the current collector plate 50 or the insulating plate 60. Furthermore, the end plates 70 and 80 are The present invention can also be applied to a configuration that also serves as the insulating plate 60. Any of such configurations inhibits heat conduction in the direction of the flow of the cooling water in the cooling water flow path 32 of the current collecting plate 50 or the insulating plate 60, and the cooling water flow path 32 of the current collecting plate 50 or the insulating plate 60. The amount of heat transfer in the direction of the cooling water flow in the cooling water channel 32 can be made lower than the amount of heat transfer in the direction perpendicular to the direction of the flow of cooling water in the cooling water channel 32. For this reason, a temperature difference is maintained between the upper part and the lower part of the current collector plate 50 or the insulating plate 60, the temperature drop of the upper part of the cell 20 at the stack end is suppressed, and the temperature distribution of the cell 20 at the stack end is reduced. It approximates the temperature distribution of the cell 20 in the other part.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The form can also be included in the scope of the present invention. Further, by combining any one of the embodiments 1-3 and any one of the embodiments 4-6, the temperature distribution of the cell 20 at the end of the stack and the temperature of the cell 20 at the other portion are combined. Can be closer to the distribution.

(Example 7)
For example, FIG. 14 shows the structure of the end plate 70H of the polymer electrolyte fuel cell stack according to the seventh embodiment. The polymer electrolyte fuel cell stack according to Example 7 has the same basic configuration as that of Example 1. In Example 7, in addition to the end plate 70H being provided with a stack end channel 72H formed in a substantially continuous S-shaped path in the upper region corresponding to the high temperature region of the cell 20, A plurality of holes 92H are provided in the lower region along the direction of the flow of the cooling water in the cooling water flow path 32 indicated by the arrow T.

  According to this, the upper region of the end plate 70H is appropriately heated corresponding to the high temperature region of the cell 20, and the lower region of the end plate 70H is lower in the direction of the cooling water flow in the cell 20. Therefore, the temperature distribution of the cell 20 at the stack end and the temperature distribution of the cell 20 at other portions can be made closer to each other.

  In each of the above embodiments, the stack end channel is formed by a groove formed in the end plate. However, the stack end channel may be provided outside the end plate. In this case, from the viewpoint of heat retention, it is preferable to cover the stack end channel with a heat insulating material.

1 is a schematic view showing a configuration of a solid polymer fuel cell stack according to Example 1. FIG. It is the schematic which shows the structure of the end plate of a polymer electrolyte fuel cell stack. (A) is a figure which shows the flow control element provided in the end plate, (B) is sectional drawing on the AA line of the flow control element shown to FIG. 3 (A). 2 is a schematic view showing a polymer electrolyte fuel cell stack according to Comparative Example 1. FIG. FIG. 4 is a diagram showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Comparative Example 1. 6 is a schematic view showing a polymer electrolyte fuel cell stack according to Comparative Example 2. FIG. 6 is a graph showing experimental results of temperature distribution measurement of each cell of the polymer electrolyte fuel cell stacks of Example 1, Comparative Example 1 and Comparative Example 2. FIG. 3 is a schematic view showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 2. FIG. 5 is a schematic view showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 3. FIG. 5 is a schematic view showing a configuration of a polymer electrolyte fuel cell stack according to Example 4. FIG. 6 is a schematic view showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 4. FIG. 10 is a view showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 5. FIG. 10 is a diagram showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 6. FIG. 10 is a view showing a configuration of an end plate of a polymer electrolyte fuel cell stack according to Example 7.

Explanation of symbols

  10 Polymer Polymer Fuel Cell Stack, 20 Cells, 22 MEA, 24 Anode Side Plate, 26 Cathode Side Plate, 30 Cooling Plate, 40 Laminate, 42 Cooling Water Supply Manifold, 44 Cooling Water Discharge Manifold, 50 Current Collector Plate, 60 insulating plate, 70, 80 end plate, 71 cooling water supply port, 72 stack end channel, 73 flow control element, 74, cooling water discharge port, 76 fuel inlet, 77 fuel outlet, 78 oxidant inlet, 79 Oxidant outlet.

Claims (5)

A membrane electrode assembly having an electrolyte membrane, an anode provided on one surface of the electrolyte membrane, and a cathode provided on the other surface of the electrolyte membrane, and an anode side plate having a fuel flow channel facing the anode A laminate in which a plurality of cells including a cathode plate having an oxidant flow path facing the cathode and a cooling plate provided with a heat medium flow path through which a heat medium for cooling the cell is provided;
An end plate that is provided at both ends of the laminate through a current collector plate and an insulating plate, and clamps the laminate;
A fuel cell stack comprising:
A stack end flow path through which the heat medium that has passed through the cooling plate flows is provided in a part of the end plate,
The fuel cell stack, wherein the stack end channel is located in a region corresponding to a high temperature region of the cell.   2. The fuel cell stack according to claim 1, further comprising a first flow rate control element that controls a flow rate of the heat medium flowing into the stack end flow path according to a temperature of the heat medium.   The flow rate of the heat medium passing through the cooling plate provided at the end of the laminated body and flowing into the cooling water discharge manifold that passes through the laminated body and communicates with the stack end flow path is determined by the cooling plate. 3. The fuel cell stack according to claim 1, further comprising a second flow rate control element that controls the temperature of the heat medium that has passed.   The heat transfer amount in the flow direction of the heat medium flowing through the heat medium flow path in the remaining part of the end plate where the stack end flow path is not provided is the flow direction of the heat medium flowing through the heat medium flow path. The fuel cell stack according to any one of claims 1 to 3, wherein the fuel cell stack is smaller than a heat transfer amount in a vertical direction. Each of the fuel flow path, the oxidant flow path, and the heat medium flow path is composed of a plurality of linear flow paths,
The fuel flowing through the fuel flow channel and the oxidant flowing through the oxidant flow channel form a parallel flow that flows downward from above, and the heat medium flowing through the heat medium flow channel flows in parallel to the fuel and the oxidant. The fuel cell stack according to any one of claims 1 to 4, wherein the fuel cell stack has a counterflow.

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