JP2008047321A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technique decreasing the change of a bonding load applied to a fuel cell stack. <P>SOLUTION: In the fuel cell stack, a power generation part bonding member 12a applying the bonding load to a power generation part 200 containing an electrolyte membrane 20 and a non-power generation part bonding member 12b applying the bonding load to a non-power generation part 300 not containing the electrolyte membrane 20 are constituted with different constituting members. A coefficient of linear expansion αce of the power generation part bonding member 12a is made lower than an average coefficient of linear thermal expansion αe obtained by weighted-averaging a coefficient of linear expansion of the constituting member of each layer constituting the power generation part 200 by the thickness of each layer. A coefficient of linear expansion αcn of the non-power generation part bonding member 12b is made the same as or almost equal to an average coefficient of linear thermal expansion αn of the non-power generation part 300. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell.

  A fuel cell usually has a cell stack in which single cells are stacked. A single cell is a power generation module in which a membrane electrode assembly (MEA) in which an electrolyte membrane is sandwiched between two electrode layers is further sandwiched between separators. The cell stack is a fuel cell stack in which a fastening load is applied in the stacking direction by a fastening member while being sandwiched by end plates from both sides.

  By the way, in such a fuel cell stack, the fastening load applied by the end plate and the fastening member may greatly change depending on the environmental temperature of the fuel cell stack and the change in the usage state. For example, when the operation of the fuel cell stack continues and the operating temperature rises, the fastening load increases or decreases depending on the difference between the thermal expansion amount in the stacking direction of the cell stack and the thermal expansion amount in the same direction of the fastening member. Tend.

  If such a fastening load increases too much, in the worst case, the components of the fuel cell stack may be damaged. Further, if the fastening load is excessively reduced, the degree of adhesion between the constituent members of the fuel cell stack may be reduced, causing gas leakage and the like, which may cause a decrease in the output of the fuel cell stack. Therefore, it is preferable that the fastening load applied to the fuel cell stack is constant.

  In order to keep such a fastening load constant, a fuel cell stack in which a spring mechanism such as a load cell is provided between the cell stack and the end plate is generally known. Further, a technique for keeping the fastening load constant with respect to the temperature change of the fuel cell stack by focusing on the linear expansion coefficients of the constituent members and fastening members of the fuel cell stack has been proposed (Patent Document 1).

JP2002-50393

  However, in the case of a fuel cell stack provided with a load cell or the like, there are problems such as an increase in cost due to an increase in the number of parts of the fuel cell stack and an increase in weight / volume. Further, the technique disclosed in Patent Document 1 focuses on only the environmental temperature of the fuel cell stack, and thus has not led to a fundamental solution.

  An object of this invention is to provide the technique which reduces the change of the fastening load added to a fuel cell stack.

  To achieve the above object, the present invention provides a fuel cell stack, in which a cell stack in which single cells are stacked, an end plate that sandwiches the cell stack from both sides, and the cell stack and the end plate are fastened. The single cell has a power generation part including an electrolyte membrane and a non-power generation part not including the electrolyte membrane, and the fastener includes a power generation part fastener and a non-power generation part fastener. The power generation unit fastener is provided in a portion closer to the power generation part than the non-power generation part fastener, and the linear expansion coefficient of the non-power generation part fastener is a line of a member constituting the non-power generation part The coefficient of expansion is approximately the same as the coefficient of linear expansion of the non-power generation part, which is an average of the expansion direction in the thickness direction, and the coefficient of linear expansion of the power generation part fastener is greater than the coefficient of linear expansion of the non-power generation part fastener.

  According to this configuration, when the fuel cell stack is operated, even if the power generation site expands in the stack stacking direction due to thermal expansion of each component and swelling of the electrolyte membrane, the expansion amount of the power generation unit fastener is the power generation site. Therefore, the fastening load applied to the power generation site can be prevented from increasing. Further, the amount of thermal expansion in the thickness direction of the single cell of each constituent member in the non-power generation part and the expansion amount of the non-power generation part fastener are substantially equal, and the fastening load applied to the non-power generation part can be made substantially constant. Therefore, a change in the fastening load applied to the fuel cell stack can be reduced when viewed from the whole fuel cell stack.

  The sum of the thermal expansion amount of the power generation site generated from the start of the fuel cell stack to the continuation of operation and the expansion amount due to swelling of the electrolyte membrane is substantially the same as the thermal expansion amount of the power generation unit fastener. It is good also as what is characterized by this.

  According to this configuration, it is possible to reduce a change in fastening load applied to the power generation unit due to thermal expansion of each component member or swelling of the electrolyte membrane.

  The power generation unit fastener may be provided in a part surrounded by the power generation part.

  According to this configuration, since the fastening load can be directly applied to the power generation site by the power generation unit fastener, the change in the fastening load applied to the fuel cell stack can be further reduced.

    The present invention can be realized in various forms, for example, in the form of a fuel cell, a fuel cell system using the fuel cell, a vehicle including the fuel cell, and the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Reference example:
B. First embodiment:
C. Second embodiment:
D. Variation:

A. Reference example:
FIG. 1 is a schematic diagram showing the configuration of a fuel cell stack 100 as a reference example. The fuel cell stack 100 has a configuration in which a cell stack 100s in which single cells 10 are stacked is sandwiched between two end plates 11a and 11b from both sides. The single cell 10 will be described later.

  The two end plates 11a and 11b have outer edge portions 11e that do not contact the cell stack 100s when they are overlapped with the cell stack 100s. Fastening members 12 penetrating the outer edge portion 11e are provided at the four corners of the two end plates 11a and 11b. The two end plates 11a and 11b fasten the cell stack 100s by the fastening member 12, and apply a fastening load in the stacking direction of the cell stack 100s.

  The fastening member 12 includes a shaft portion 12s extending in the stacking direction of the cell stack 100s. Also, nut portions 12n are provided at both ends of the shaft portion 12s. The fastening member 12 may have another shape, and a plurality of fastening members 12 may be further provided at portions other than the four corners of the two end plates 11a and 11b.

  FIG. 2A is a schematic view showing a cross section of the single cell 10 constituting the fuel cell stack 100. The single cell 10 is a power generation module in which a membrane electrode assembly MEA is sandwiched between two separators SP (described later). The membrane / electrode assembly MEA is obtained by sandwiching an electrolyte membrane 20 showing good proton conductivity in a wet state between two electrode layers 21 and 22, and a seal gasket 30 is formed on the outer peripheral edge thereof.

  A gas diffusion layer for supplying fuel gas and oxidizing gas (both are collectively referred to as “reactive gas”) to the entire electrode layers 21 and 22 on the outer surfaces of the two electrode layers 21 and 22 that do not contact the electrolyte membrane 20 25 are provided. The gas diffusion layer 25 is provided so that the outer surface not in contact with the electrode layers 21 and 22 is in contact with the separator SP when the membrane electrode assembly MEA is sandwiched between the separators SP. The two electrode layers 21 and 22 are preferably provided with a catalyst layer for promoting an electrochemical reaction, for example, by supporting platinum or the like.

  The seal gasket 30 is for preventing leakage of reaction gas supplied to the membrane electrode assembly MEA to the outside of the single cell 10 and cross leakage. Here, “cross leak” means that a part of the fuel gas supplied to the anode electrode layer 21 leaks to the cathode electrode layer 22 as it is without being subjected to the fuel cell reaction. Furthermore, the seal gasket 30 is provided with manifold holes M1 to M6 which are a plurality of through holes for supplying the reaction gas and the refrigerant to each single cell 10 of the cell stack 100s (FIG. 1).

  The manifold holes M1 to M6 include reaction gas and refrigerant supply manifold holes M1 to M3 and discharge manifold holes M4 to M6. More specifically, the supply manifold holes M1 to M3 include a fuel gas supply manifold hole M1, an oxidizing gas supply manifold hole M2, and a refrigerant supply manifold hole M3. The discharge manifold holes M4 to M6 include a fuel gas discharge manifold hole M4, an oxidizing gas discharge manifold hole M5, and a refrigerant discharge manifold hole M6. The supply manifold holes M1 to M3 and the discharge manifold holes M4 to M6 are respectively provided in portions facing each other with the electrolyte membrane 20 interposed therebetween. The manifold holes M1 to M6 may have other configurations.

  The separator SP includes an anode plate 41 in contact with the gas diffusion layer 25 on the anode electrode layer 21 side, and a cathode plate 43 in contact with the gas diffusion layer 25 on the cathode electrode layer 22 side. Further, the separator SP includes a cooling plate 42 that is sandwiched between two plates 41 and 43. Like the membrane electrode assembly MEA, the separator SP is provided with manifold holes M1 to M6 which are through holes. The manifold holes M1 to M6 of the separator SP are connected to the manifold holes M1 to M6 of the membrane electrode assembly MEA.

  Since the three plates 41, 42, and 43 are made of conductive metal plates, the separator SP has a function of collecting electricity generated by the fuel cell reaction. The cooling plate 42 is provided with a plurality of refrigerant flow paths (not shown) in parallel through the cooling plate 42 in the thickness direction and in the direction from the refrigerant supply manifold hole M3 to the refrigerant discharge manifold hole M6. Yes. The refrigerant flow path is connected to the manifold holes M3 and M6 and has a function of cooling the single cell 10 when the refrigerant flows therein.

  A protrusion (not shown) called a lip is provided on the surface of the seal gasket 30. The lip forms a seal line (not shown). When the lip is pressed against the separator SP, the manifold holes M1, M2, M4, M5 are provided between the seal gasket 30 and the two plates 41, 43. A flow path for supplying the reaction gas from the gas diffusion layer 25 to the gas diffusion layer 25 is formed. That is, the separator SP has a function of supplying a reactive gas to the membrane electrode assembly MEA.

  The separator SP does not have to be a three-layer separator provided with three plates 41, 42, and 43. For example, the separator SP may be provided with a groove serving as a reaction gas flow path on the contact surface with the membrane electrode assembly MEA.

  FIG. 2B is a schematic view when the single cell 10 is assembled as the fuel cell stack 100 and viewed from the end plate 11a side. Similarly to the single cell 10, the end plate 11a is also provided with manifold holes M1 to M6 that are through holes. The manifold holes M1 to M6 of the end plate 11a are connected to the manifold holes M1 to M6 provided in the single cell 10. The manifold holes M <b> 1 to M <b> 6 are connected to a reaction gas supply unit (not shown) and a refrigerant supply unit (not shown) for supplying a reaction gas and a refrigerant outside the fuel cell stack 100.

  In this specification, the part including the electrolyte membrane 20 of the single cell 10 and mainly performing the fuel cell reaction is referred to as the “power generation unit 200”, and the part not including the electrolyte film 20 and performing the fuel cell reaction. Is referred to as a “non-power generation unit 300”. That is, the power generation unit 200 has a configuration in which the electrolyte membrane 20, the electrode layers 21, 22 and the gas diffusion layer 25 are mainly stacked, and the non-power generation unit 300 mainly has the seal gasket 30 and the separator SP stacked. It is the structure which was made.

  In general, the temperature change of a fuel cell is remarkable depending on the usage condition. Specifically, the operating temperature may change from −30 ° C. to 60 ° C. In general, since the fuel cell is preferably operated in a wet state, the fuel cell is kept in a wet state during a driving operation even if it is in a dry state at the time of startup.

  Each component of the fuel cell stack expands by an amount corresponding to its linear expansion coefficient when the operating temperature of the fuel cell stack rises. Further, it is generally known that the electrolyte membrane constituting the electrolyte membrane is significantly swollen by humidity. Here, the total expansion amount in the stacking direction of the constituent members of the single cell of the fuel cell stack is referred to as “stack expansion amount”. The stack expansion amount is the sum of the expansion amount due to heat and the expansion amount due to wetting. Further, the amount of expansion of the fastening member that fastens the fuel cell stack in the stacking direction of the single cells is referred to as “fastening member expansion amount”.

  If there is a difference between the amount of expansion of the stack that occurs between the start of the fuel cell stack and the continuous operation, and the amount of expansion of the fastening member, the fastening load applied to the fuel cell stack by the fastening member (hereinafter referred to simply as “fastening”). Called “load”). More specifically, the fastening load increases when the fastening member expansion amount is smaller than the stack expansion amount, and the fastening load decreases when the fastening member expansion amount is larger than the stack expansion amount.

  When the fastening load increases significantly, there is an increased possibility of damage to each component such as destruction of the electrolyte membrane, and when the fastening load decreases significantly, it may cause a decrease in fuel cell stack output and gas leakage. . Therefore, it is generally preferable that the fastening load is constant regardless of the environmental temperature and operating state of the fuel cell stack.

  FIG. 3A is a graph showing a change in fastening load with respect to a change in operating temperature of the fuel cell stack 100. Graph G1 shows the case where the fuel cell stack 100 changes in temperature from −30 ° C. to 60 ° C. in a dry state, and graph G2 shows the case where the fuel cell stack 100 changes in temperature from −30 ° C. to 60 ° C. Is shown. That is, the change in the fastening load in these graphs G1 and G2 is caused by the difference between the stack expansion amount due to thermal expansion (hereinafter referred to as “stack thermal expansion amount”) and the fastening member expansion amount. Yes.

  The difference between the stack thermal expansion amount and the fastening member expansion amount is caused by the difference between the linear expansion coefficient αs of the fuel cell stack and the linear expansion coefficient αc of the fastening member. Here, in general, the linear expansion coefficient in the stacking direction of the laminate can be obtained by weighted averaging of the linear expansion coefficient of each layer by the thickness of each layer. The linear expansion coefficient αs of the fuel cell stack can also be obtained from the linear expansion coefficient of the constituent members of each layer and the thickness thereof.

  As can be understood from the two graphs G1 and G2, in this fuel cell stack 100, the fastening member expansion amount is larger than the stack thermal expansion amount, and the fastening load decreases as the operating temperature rises. This is the same both in the dry state and in the wet state. However, in the wet fuel cell stack 100, an expansion amount due to swelling of the electrolyte membrane 20 is added, so that the fastening load is higher than that in the dry fuel cell stack 100. As will be described later, in the fuel cell stack 100, the member so that the fastening load at the time of starting (operating temperature -30 ° C; dry state) and the fastening load at the time of continuous operation (operating temperature 60 ° C; wet state) are substantially the same. Is selected.

  FIG. 3B is a table showing an example of the linear expansion coefficient of each component of the fuel cell stack 100 and the calculation results of the linear expansion coefficient αs and the expansion amount of the fuel cell stack. In calculating the expansion amount, the power generation unit 200 per unit cell 10 when the operating temperature of the fuel cell stack 100 is changed from −30 ° C. to 60 ° C. before the start-up to the continuous operation (FIG. 2 ( The amount of expansion in the thickness direction in B)) is calculated.

  In the single cell 10 of the reference example, the separator SP is made of titanium (thickness 4600 μm, linear expansion coefficient 8.2 × 10 −6 / ° C.), and the gas diffusion layer 25 is carbon cloth (thickness 150 μm × 2 layers, linear expansion coefficient). 96 × 10 −6 / ° C.). The electrolyte membrane 20 including the electrode layers 21 and 22 is calculated as a Gore membrane (thickness 30 μm, linear expansion coefficient 46 × 10 −6 / ° C.). Then, the linear expansion coefficient αs of the fuel cell stack 100 is 13.8 × 10 −6 / ° C., and the thermal expansion amount E10D of the single cell 10 with respect to a temperature change amount of 90 ° C. from −30 ° C. to 60 ° C. is about 6 .1 μm.

  It is known that the electrolyte membrane 20 exhibits an expansion amount of about 20% with respect to its thickness due to swelling in a wet state in which operation is continued from a dry state at the time of startup of the fuel cell stack 100. Therefore, when the expansion amount E10W of the single cell 10 in the wet state is obtained by adding the expansion amount 6.0 μm due to the swelling of the electrolyte membrane 20 to the expansion amount E10D obtained above, it is about 12.1 μm.

  On the other hand, when glass epoxy resin (linear expansion coefficient 28 × 10 −6 / ° C.) is adopted as a constituent member of the fastening member 12, the expansion of the fastening member 12 with respect to a temperature change amount 90 ° C. per unit cell 10 thickness (4930 μm). The amount E12 is about 12.4 μm. This substantially coincides with the expansion amount E10W (= 12.1 μm) of the single cell 10 in the wet state.

  Therefore, the fastening load of the fuel cell stack 100 is kept substantially constant as shown by the arrow in FIG. The linear expansion coefficient (13.8 × 10 −6 / ° C.) of the single cell 10 is lower than the linear expansion coefficient (28 × 10 −6 / ° C.) of the glass epoxy resin.

  By the way, the expansion amount E10W of the single cell 10 described above is calculated based on the linear expansion coefficient obtained according to the configuration of the power generation unit 200. However, as shown in FIG. 2B, the single cell 10 has a non-power generation unit 300 that hardly includes the electrolyte membrane 20, and the power generation unit 200 and the non-power generation unit 300 expand in the stacking direction. And the linear expansion coefficient is different. Therefore, there is a difference in the change in the fastening load between the case where the fastening member 12 is provided in a part close to the power generation unit 200 and the case where the fastening member 12 is provided in a part close to the non-power generation unit 300.

  Therefore, a configuration of a fuel cell stack capable of maintaining a fastening load at a more stable value based on the concept shown in the reference example will be described below as an embodiment of the present invention.

B. First embodiment:
FIG. 4 is a perspective view showing a fuel cell stack 100A as a first embodiment of the present invention. The fuel cell stack 100A of the first embodiment is substantially the same as the fuel cell stack 100 of the reference example except that two types of fastening members 12a and 12b are provided instead of the fastening member 12.

  The fuel cell stack 100A of the first embodiment is provided with two types of plate-like fastening members 12a and 12b having different constituent members. The fastening members 12a and 12b are arranged such that two opposing end faces are in contact with the sides of the end plates 11a and 11b, respectively, and are fixed by screws 13 that pass through the end plates 11a and 11b, whereby the fuel cell stack 100a is fixed. It is concluded.

  Among the fastening members 12a and 12b, the one provided in the site close to the power generation unit 200 of the single cell 10 is called the power generation unit fastening member 12a, and the one provided in the site close to the non-power generation unit 300 is the non-power generation unit fastening member. Called 12b. More specifically, a set of fastening members arranged so as to be in contact with two sides of the end plate 11a where the manifold holes M1 to M6 are not provided is the power generation unit fastening member 12a, and is in contact with the remaining two sides. One set of fastening members arranged in the non-power generation part fastening member 12b.

  The power generation unit fastening member 12a and the non-power generation unit fastening member 12b do not have to be plate-shaped, and may have other configurations as long as a fastening load can be applied to the fuel cell stack.

  FIG. 5 is a table showing an example of the linear expansion coefficient of each component of the fuel cell stack 100A of the first embodiment and the calculation results of the linear expansion coefficient and the expansion amount of the fuel cell stack 100A. As described above, since the power generation unit 200 and the non-power generation unit 300 have different layer structures, the table shown in FIG. 5 shows the power generation unit 200 in the upper part and the non-power generation part 300 in the lower part. In the calculation of the expansion amount, as in the reference example, the thickness per unit cell 10 when the operating temperature of the fuel cell stack 100A is changed from −30 ° C. to 60 ° C. from the start to the continuous operation. Calculate the amount of expansion in the direction.

  Since the layer structure of the power generation unit 200 is the same as the layer structure of the fuel cell stack 100 shown in FIG. 3B, the linear expansion coefficient αe of the power generation unit 200 is the fuel cell stack 100 shown in FIG. Is the same as the linear expansion coefficient αs. The same applies to the expansion amounts E10D and E10W. The power generation unit fastening member 12a can be made of glass epoxy resin, like the fastening member 12 of the reference example. Therefore, the linear expansion coefficient αce of the power generation unit fastening member 12a is the same as the linear expansion coefficient αc of the fastening member 12 of the reference example.

  Next, the amount of expansion in the stacking direction with respect to the temperature change of 90 ° C. is calculated based on the linear expansion coefficient αn of the non-power generation unit 300. In the non-power generation unit 300, the separator SP is made of titanium (thickness 4600 μm, linear expansion coefficient 8.2 × 10 −6 / ° C.), and the seal gasket 30 is silicon rubber (thickness 2000 μm, linear expansion coefficient 30 × 10 −6 / ° C). Therefore, the non-power generation part linear expansion coefficient αn is 14.8 × 10 −6 / ° C., and the expansion amount E300 in the stacking direction with respect to the temperature change amount 90 ° C. of the non-power generation part 300 is 8.8 μm.

  The thickness of the seal gasket 30 when assembled to the fuel cell 100A is 330 μm in total, which is the total thickness of the electrolyte membrane 20 (including the electrode layers 21 and 22) and the two gas diffusion layers 25 of the power generation unit 200. Compressed to be equal. However, in the calculation of the expansion amount of the non-power generation unit 300, the calculation is executed using the thickness (= 2000 μm) when the seal gasket 30 is not compressed.

  The non-power generation portion fastening member 12b is made of stainless steel (SUS304). The linear expansion coefficient αcn of the non-power generation portion fastening member 12b is 14.8 × 10 −6 / ° C., and the expansion amount E12b in the stacking direction with respect to the temperature change amount 90 ° C. is 8.8 μm. The linear expansion coefficient αn of the non-power generation unit 300 and the linear expansion coefficient αcn of the non-power generation unit fastening member substantially match, and the expansion amounts E300 and E12b also substantially match. Therefore, the fastening load in the non-power generation unit 300 can be kept constant.

  Thus, the power generation unit fastening member 12a employs a member having a linear expansion coefficient αc lower than the linear expansion coefficient αe of the power generation unit 200. Further, the non-power generation unit fastening member 12b employs a member having a value that is the same as or substantially equal to the linear expansion coefficient αn of the non-power generation unit 300 (for example, a value of about linear expansion coefficient αn ± 10%).

  As a result, it is possible to reduce the change in the fastening load for each portion of the fuel cell stack regardless of the environmental temperature and the operating state of the fuel cell stack. Therefore, it is possible to reduce the possibility of breakage of the constituent members of the fuel cell stack and the occurrence of gas leakage due to changes in the fastening load.

  In particular, as described above, the fuel cell stack is often in a dry state at low temperature startup. By reducing the difference in fastening load between low temperature startup and continued operation, it is possible to reduce the decrease in surface pressure at the contact surface between the electrode layer, the electrolyte membrane and the gas diffusion layer, and between other components It is also possible to reduce the contact resistance. Therefore, the fuel cell can be started up smoothly.

  Note that the power generation unit fastening member 12a is configured such that the sum of the amount of thermal expansion in the stacking direction of the power generation unit 200 generated from the start of the fuel cell stack 100A to the time of continuous operation and the amount of expansion due to swelling of the electrolyte membrane 20 is The constituent members may be selected so that the amount of expansion of the fastening member 12a in the same direction is substantially the same. Here, “the expansion amount is substantially the same” means, for example, a case where one has a value in a range of 0.9 to 1.1 times the expansion amount of the other.

  In addition, you may employ | adopt aluminum (linear expansion coefficient 23 * 10-6 / degreeC) instead of glass epoxy resin as the electric power generation part fastening member 12a. In this case, the expansion amount E12a with respect to the temperature change amount 90 ° C. of the fastening member 12a is 10.2 μm. This is a value lower than the expansion amount E10W of the single cell 10 in the wet state of the single cell 10 of the power generation unit 200 = 12.1 μm. By the way, when the same SUS304 as the non-power generation part fastening member 12b is adopted as the power generation part fastening member 12a, the expansion amount E12a of the power generation part fastening member 12a is 6.6 μm. Accordingly, the change in the fastening load is reduced when aluminum is used as the power generation unit fastening member 12a than when the same SUS304 is used as the non-power generation unit fastening member 12b.

C. Second embodiment:
FIG. 6A is a perspective view showing a fuel cell stack 100B as a second embodiment of the present invention. The fuel cell stack 100B of FIG. 6A is the same as the fuel cell stack 100A of the first embodiment except that the shapes and positions of the two types of fastening members 12a and 12b are different.

  The two fastening members 12a and 12b are the same as those in the reference example, and include a shaft portion 12s and a nut portion 12n. The power generation unit fastening member 12a is provided so as to penetrate the power generation unit 200, and the non-power generation unit fastening member 12b is provided at the four corners of the end plates 11a and 11b. The two fastening members 12a and 12b may have other configurations. For example, the non-power generation portion fastening member 12b may be provided in a plate shape as in the first embodiment. The power generation unit fastening member 12a may be configured to be able to apply a fastening load directly to the power generation unit 200.

  FIG. 6B is a perspective view showing the membrane electrode assembly MEA2 included in the single cell 10 constituting the fuel cell stack 100B. The membrane electrode assembly MEA2 is the same as the membrane electrode assembly MEA of the reference example except that a through-hole 14 through which the power generation unit fastening member 12a passes and a seal gasket 31 that seals the inner wall surface of the through-hole 14 are provided. The same. The seal gasket 31 is provided to prevent cross leak in the through hole 14.

  Since the power generation unit fastening member 12a penetrates the power generation unit 200, a fastening load is directly applied to the power generation unit 200. Therefore, the fuel cell stack 100B can further reduce the change in the fastening load than the fuel cell stack 100A of the first embodiment. Therefore, the possibility of breakage of constituent members of the fuel cell stack and occurrence of gas leakage is further reduced.

D. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
The thicknesses of the constituent members and the respective layers in the above embodiment are merely examples for explaining the first embodiment, and are not limited thereto. Other components may be adopted, and the thickness of each layer can be arbitrarily changed in accordance with the components.

D2. Modification 2:
In the above embodiment, the expansion amount is calculated for each single cell, but the expansion amount in the stacking direction of the entire fuel cell stack may be calculated in consideration of the expansion amount in the thickness direction of the end plate. good.

Schematic which shows the fuel cell stack 100 in a reference example. Explanatory drawing for demonstrating the single cell 10 in a reference example. The graph which shows the change of the fastening load with respect to the temperature change of a fuel cell stack, and the table | surface which shows the linear expansion coefficient and expansion amount of a fuel cell stack. 1 is a schematic diagram showing a fuel cell stack 100A of a first embodiment. The table | surface which shows the linear expansion coefficient and expansion amount of 100 A of fuel cell stacks of 1st Example. Schematic which shows the fuel cell stack 100B of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Single cell 11a ... End plate 11e ... Outer edge part 12 ... Fastening member 12a ... Power generation part fastening member 12b ... Non power generation part fastening member 12n ... Nut part 12s ... Shaft part 13 ... Screw 14 ... Through-hole 20 ... Electrolyte membrane 21 ... Anode electrode layer 22 ... Cathode electrode layer 25 ... Gas diffusion layer 30, 31 ... Seal gasket 41 ... Anode plate 42 ... Cooling plate 43 ... Cathode plate 100 ... Fuel cell stack 100A ... Fuel cell stack 100B ... Fuel cell stack 100s ... Cell stack 200 ... Power generation unit 300 ... Non-power generation unit M1-M3 ... Supply manifold hole M4-M6 ... Discharge manifold hole MEA, MEA2 ... Membrane electrode assembly SP ... Separator

Claims (3)

A fuel cell stack,
A cell stack in which single cells are stacked;
An end plate sandwiching the cell stack from both sides;
A fastener for fastening the cell stack and the end plate;
With
The single cell has a power generation site including an electrolyte membrane and a non-power generation site not including an electrolyte membrane,
The fastener includes a power generation unit fastener and a non-power generation unit fastener,
The power generation part fastener is provided in a part closer to the power generation part than the non-power generation part fastener,
The linear expansion coefficient of the non-power generation part fastener is substantially the same value as the non-power generation part linear expansion coefficient, which is the average in the thickness direction of the linear expansion coefficient of the members constituting the non-power generation part,
The fuel cell stack, wherein a linear expansion coefficient of the power generation unit fastener is larger than a linear expansion coefficient of the non-power generation unit fastener. The fuel cell stack according to claim 1, wherein
The sum of the amount of thermal expansion of the power generation site generated from the start of the fuel cell stack to the time of continued operation and the amount of expansion due to swelling of the electrolyte membrane is substantially the same as the amount of thermal expansion of the power generation unit fastener. A fuel cell stack characterized by that. A method according to claim 1 or claim 2, wherein
The fuel cell stack, wherein the power generation unit fastener is provided in a region surrounded by the power generation region.

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