JP2006040807A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell preventing a gas leakage beforehand caused by temperature changes and temperature deviations of the fuel cell. <P>SOLUTION: The fuel cell 1 is constituted so that a fuel pole is arranged on one face of the solid polymer membrane and an oxidizer pole is arranged on the other face of the solid polymer membrane, and so that a separator in which a fuel gas flow-passage is formed on one face of a solid polymer membrane and a separator in which an oxidizer gas flow-passage is formed on the other side are confronted. The fuel cell 1 is provided with a gas manifold 23 outside a laminate S composed by laminating a plurality of unit fuel cells which generate electric power by receiving supply of the fuel gas and the oxidizer gas. The gas manifold 23 and the laminate S are fastened and fixed by a first fastening member 25 having a positive thermal expansion coefficient and a second fastening member 26 having a negative thermal expansion coefficient in the direction perpendicular to the laminating direction of the unit fuel cells so as to cover the outer periphery of the gas manifold 23 and the laminate S so as to cover the outer periphery of the gas manifold 23 and the laminate S. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell, and is particularly suitable for application to a technique for preventing gas leakage in a polymer electrolyte fuel cell (PEFC).

  Conventionally, there is known a fuel cell in which a fuel gas such as hydrogen gas and an oxygen-containing oxidant gas are supplied to a fuel cell stack to cause an electrochemical reaction via an electrolyte and to directly extract electric energy between electrodes. It has been.

  Here, the fuel cell stack includes a separator in which a fuel electrode is disposed on one surface of the solid polymer film, an oxidant electrode is disposed on the other surface, and a fuel gas channel is formed on the one surface, and an oxidant on the other surface. A unit fuel cell (hereinafter referred to as a fuel cell) as a fuel cell, which is configured to face a separator having a gas flow path and generates electric power (generates an electromotive force) by receiving supply of fuel gas and oxidant gas. Is simply referred to as a single cell) to form a laminated body, and a current collector plate, an insulating plate, and an end plate as terminal members are arranged at both ends of the laminated body.

  Also, the fuel cell stack has holes for supplying and discharging gas to each unit cell, and holes for supplying and discharging cooling water for cooling the fuel cell stack, that is, gas manifolds inside or outside. Provided.

  In addition to high power generation efficiency, this fuel cell has the advantage of extremely low emissions of harmful substances, so it is not only applied to stationary power generation such as power plants and household generators, but also In recent years, it has attracted attention as a fuel cell vehicle used as a drive source.

  However, in a fuel cell stack provided with the gas manifold inside (hereinafter referred to as an internal manifold), when operating using reformed gas, carbon monoxide is provided downstream of the fuel gas flow path of each unit cell. Since the concentration of (CO) is increased, the temperature is lowered due to electrode poisoning, which may further promote the electrode poisoning.

  And, as one of the methods to mitigate such a decrease in battery performance, the gas manifold is provided outside as a structure that secures the gas supply section and gas discharge section from the gas manifold to each unit cell as wide as possible. The fuel cell stack (hereinafter referred to as the external manifold) has been reviewed.

As an external manifold type fuel cell of this type, for example, as disclosed in Patent Document 1, a rigid body is provided on the side surface of the fuel cell stack via a gas-tight and non-conductive seal member, and the seal A member in which an external manifold whose members are made of an elastic body is arranged is known. The external manifold type fuel cell has a structure in which at least a part of the external manifold is fitted into the side surface of the laminate.
JP 2001-135341 A (pages 4 and 5; FIGS. 1 and 2)

  In the fuel cell described in Patent Document 1, by adopting the above-described configuration, it is possible to smooth the side surface of the stacked body in contact with the seal surface of the external manifold. Gas sealability can be improved.

  Further, when the external manifold is made of a rigid body and the airtight material is made of an elastic body, the thickness creep in the stacking direction of the stacked body is absorbed, and the gas sealability between the external manifold and the side surface of the stacked body is further improved. be able to.

  Furthermore, at least a part of the external manifold is fitted into the side surface of the laminate, thereby reducing the deflection of the internal partition due to the pressure in the external manifold and improving the sealing performance between the external manifold and the side surface of the laminate. It becomes possible.

  However, as in the fuel cell described in Patent Document 1, in the configuration in which the external manifold is disposed on the side surface of the stacked body through a gas-tight and non-conductive seal member, the external manifold and the single cell (that is, In this case, the separator) and the sealing member mainly repeat thermal expansion and contraction due to temperature changes before and after power generation.

  Then, due to the thermal expansion and contraction, the tightening force between the external manifold and the fuel cell decreases due to the difference in thermal expansion coefficient of each material, so that a gap is generated between the external manifold and the fuel cell. Or the seal member peels off, and there is still an insufficient problem that gas leaks from these gaps.

  In addition, since the necessary electric power cannot be obtained due to the gas leakage as described above, in a fuel cell vehicle equipped with such a fuel cell, the distance that can be traveled is reduced. . In particular, when a large amount of hydrogen leaks (4% to 75% of the air capacity), it can be a serious problem in terms of safety.

  Therefore, the present invention has been made in view of such conventional problems, and an object of the present invention is to provide a fuel cell that can prevent gas leakage due to temperature change and temperature deviation of the fuel cell.

In the present invention, a fuel electrode is disposed on one surface of the solid polymer film, an oxidant electrode is disposed on the other surface, and a fuel gas channel is formed on the one surface, and an oxidant gas flow is disposed on the other surface. A gas manifold is provided outside a laminate formed by laminating a plurality of unit fuel cells that generate electric power upon receiving the supply of the fuel gas and the oxidant gas. In the fuel cell, the gas manifold and the stacked body have a positive thermal expansion coefficient so as to cover the outer periphery of the gas manifold and the stacked body in a direction orthogonal to the stacking direction of the unit fuel cell. 1 fastening member and the 2nd fastening member which has a negative thermal expansion coefficient, It is characterized by being fastened and fixed.
In the present invention, a separator in which a fuel electrode is disposed on one surface of the solid polymer film, an oxidant electrode is disposed on the other surface, and a fuel gas flow path is formed on the one surface, and an oxidant on the other surface. A gas manifold is formed outside a laminate formed by laminating a plurality of unit fuel cells that are configured to face a separator in which a gas flow path is formed and receive power from the fuel gas and the oxidant gas. A first fuel cell having a positive coefficient of thermal expansion so as to cover the gas manifold and the stack in the stacking direction of the unit fuel cells so as to cover the outer periphery of the gas manifold and the stack. And a second fastening member having a negative coefficient of thermal expansion.

  According to the present invention, the first fastening member having a positive thermal expansion coefficient and the negative thermal expansion coefficient as a fastening member for fixing the gas manifold to the outside of the stacked body formed by stacking a plurality of unit fuel cells. The second fastening member is used, and the first and second fastening members are arranged so as to cover the outer periphery of the gas manifold and the stack in the stacking direction of the unit fuel cells or in a direction orthogonal to the stacking direction. By fixing, the fastening force of the fastening member on the unit fuel cell (that is, the fuel cell) can be increased by the first fastening member at a high temperature during power generation. On the other hand, the fastening force of the fastening member to the unit fuel cell can be increased by the second fastening member even at a low temperature (or below freezing point) during the stop.

  Therefore, according to the present invention, it is possible to avoid the formation of a gap between the gas manifold and the laminate in both the high temperature state during start-up of the fuel cell and the low temperature state during stoppage. It is possible to prevent gas leakage due to the occurrence of gas and peeling of the seal member provided between the gas manifold and the laminate. In addition, since it is possible to prevent the occurrence of gas leakage in this way, the necessary power can be obtained practically enough, and in a fuel cell vehicle equipped with such a fuel cell, the cruising distance is reduced. It is possible to prevent and secure the distance sufficiently. Further, there is no possibility that a large amount of hydrogen leaks (4% to 75% of the air capacity), and sufficient safety can be ensured.

  Thus, according to the present invention, it is possible to realize a fuel cell that can prevent gas leakage due to temperature change and temperature deviation of the fuel cell.

  Before describing an embodiment of a fuel cell according to the present invention, a solid polymer fuel cell system using a solid polymer fuel cell which is a fuel cell of the present invention will be briefly described with reference to the drawings. To do.

[Outline of polymer electrolyte fuel cell system]
FIG. 1 is a schematic configuration diagram showing an embodiment of a polymer electrolyte fuel cell system to which a fuel cell of the present invention is applied.

  As shown in FIG. 1, the polymer electrolyte fuel cell 1 is provided with a fuel cell stack 2, and a fuel electrode 3 and an oxidant electrode 4 are disposed in the fuel cell stack 2. A fuel supply line 6, which is a gas supply flow path for fuel gas, is connected to the fuel electrode 3 of the fuel cell stack 2, and a gas discharge flow for fuel gas that exhausts the reacted gas supplied to the fuel electrode 3. A fuel exhaust line 7 is connected. The fuel supply line 6 is provided with a hydrogen supply source 8 for supplying hydrogen as fuel, while the fuel exhaust line 7 is provided with a hydrogen-containing gas processing device 9.

  The oxidant electrode 4 of the fuel cell stack 2 is connected to an oxidant supply line 10 that is a gas supply channel for the oxidant gas, and exhausts the hydrogen-containing gas that has been supplied to the oxidant electrode 4 and reacted. An oxidant exhaust line 11 that is a gas discharge flow path for the oxidant gas to be connected is connected. The oxidant supply line 10 is provided with an oxidant supply source 12 for supplying an oxidant. Furthermore, an electric wiring 14 is connected to the fuel electrode 3 and the oxidant electrode 4 of the fuel cell stack 2 via an electric control device 13.

  Incidentally, in FIG. 1, the flow of the fuel gas and the oxidant gas during power generation of the polymer electrolyte fuel cell 1 is shown using solid arrows a and b, respectively. A current flow during power generation is indicated by a broken-line arrow c.

  In the power generation of the polymer electrolyte fuel cell 1, a hydrogen-containing gas as a fuel gas is supplied from the hydrogen supply source 8 to the fuel electrode 3 of the fuel cell stack 2, and oxygen as an oxidant gas from the oxidant supply source 12 to the oxidant electrode 4. Each of the contained gases is supplied, and the generated electromotive force is collected and output by the electric control device 13.

[Configuration of fuel cell]
Next, a polymer electrolyte fuel cell as a fuel cell according to the present invention will be described in detail with reference to the drawings using first to third embodiments.

“First Embodiment”
2 and 3 show a first embodiment of a fuel cell according to the present invention, FIG. 2 is a perspective view schematically showing a solid polymer fuel cell of the present invention, and FIG. 3 is a solid diagram of FIG. FIG. 4 is an enlarged cross-sectional view showing a fuel cell stack in the solid polymer fuel cell of FIG. 2.

  As shown in FIGS. 2 and 3, the fuel cell stack 2 is configured by a stacked body S in which a plurality of unit cells 15 as unit fuel cells are stacked. As shown in FIG. 4, the unit cell 15 includes a fuel electrode 3 and an oxidant electrode 4, and a solid polymer electrolyte membrane 16 is sandwiched between the fuel electrode 3 and the oxidant electrode 4. Yes. The fuel electrode 3 and the oxidant electrode 4 are each provided with a gas diffusion layer 17 and a catalyst layer 18. Further, the fuel electrode 3 is provided with a fuel gas passage 19, while the oxidant electrode 4 is provided with an oxidant gas passage 20.

  Note that, in the stacked body S in which a plurality of unit cells 15 constituting the fuel cell stack 2 are stacked, the fuel electrode 3 and the oxidant electrode 4 are alternately stacked and supplied to the fuel electrode 3 and the oxidant electrode 4 respectively. In order to separate the gases, separators 21 are sandwiched between the individual unit cells 15, and each unit cell 15 is fixed by rods L provided through the four corners.

  When a hydrogen-containing gas is supplied to the fuel cell stack 2 from the fuel supply line 6 (see FIG. 1), the fuel gas flow path provided in the fuel electrode 3 of each unit cell 15 constituting the fuel cell stack 2. 19 is supplied with a hydrogen-containing gas. At the same time, when oxygen supply gas is supplied to the fuel cell stack 2 from the oxidant supply line 10 (see FIG. 1), the oxidant provided in the oxidant electrode 4 of each unit cell 15 constituting the fuel cell stack 2. An oxygen-containing gas is supplied to the gas flow path 20. Then, the supplied hydrogen and oxygen react in the solid polymer electrolyte membrane 16, whereby the polymer electrolyte fuel cell 1 generates power.

  In addition to this configuration, in the case of the present embodiment, the stacked body S of the unit cells 15 constituting the polymer electrolyte fuel cell 1 is used as terminal members located at both ends in the stacking direction as shown in FIG. An end plate 22 is provided. Here, the terminal member does not generate power by itself, and has a current collecting function for taking out the electric power generated by the fuel cell stack 2 to the outside, and an application for pressurizing the stacked body S of the unit cells 15 in the stacking direction. It has at least one pressure function.

Further, as shown in FIG. 3, the fuel cell stack 2 has one side surface of each gas supplied to the unit cell 15 from the external fuel supply line 6 and the oxidant supply line 10 (see FIG. 1). The stacking direction of the single cells 15 in the stacked body S with respect to the gas manifold 23 that connects and connects each gas exhausted from the single cells 15 to the fuel exhaust line 7 and the oxidant exhaust line 11 (see FIG. 1). Are connected so as to be fitted in a direction perpendicular to the direction. In this case, the gas manifold 23 is formed using an elastic non-conductive material. A seal member such as an adhesive (not shown) is interposed between the stack S of the fuel cell stack 2 and the gas manifold 23.
And the laminated body S and the gas manifold 23 connected in this way are positive heat | fever via the nonelectroconductive protection sheet 24 on the outer peripheral surface except the both ends (namely, end plate 22 and 22 side) of the laminated body S. The first fastening member 25 having an expansion coefficient and the second fastening member 26 having a negative thermal expansion coefficient are fastened and fixed.

  Note that the gas manifold 23 may be fixed to the stacked body S with an adhesive as needed before being fastened by the first and second fastening members 25 and 26. The protective sheet 24 may be omitted as necessary.

  The first and second fastening members 25, 26 are a set of two, provided in a direction substantially perpendicular to the stacking direction of the unit cells 15, and covering the outer periphery of the gas manifold 23 and the stacked body S. Thus, about 3 to 10 positions are arranged between the end plates 22 of the laminate S. In the present embodiment, by binding the fastening members that are a set of the first fastening member 25 and the second fastening member 26 of different types at three locations near both ends and the substantially central portion of the laminate S, The gas manifold 23 was fixed to the side surface of the laminate S. Of course, the number of the first and second fastening members 25 and 26 described here is one example of an ideal arrangement, and the present invention is not limited to this.

  As the first fastening member 25 having a positive thermal expansion coefficient, a metal having a linear expansion coefficient of about 10 −6 [K−1] to 10 −5 [K−1], or a linear expansion coefficient of 10 −5 [ A candidate is a polymer material having a glass transition point of about K-1] to 10-3 [K-1] above the power generation temperature. In particular, a stainless steel material (SUS304 material) having a linear expansion coefficient of about 1.7 × 10 −5 [K-1] or a polymer having a linear expansion coefficient of about 1.3 × 10 −4 [K-1]. It is preferable to use a heat stretchable material such as a polyamide resin material.

  Further, by using a non-conductive material as the first fastening member 25, a short circuit between the stacked body S of the unit cells 15 and the gas manifold 23 can be prevented.

  On the other hand, as the second fastening member 26 having a negative thermal expansion coefficient, glass ceramics or fibers are preferable. In particular, a poly (p-phenylenebenzobisoxazole) fiber having a linear expansion coefficient of about −7.0 × 10 −6 [K−1], or a linear expansion coefficient of −7.6 × 10 −6 [K−1]. It is preferable to use a heat shrinkable material such as NEX-I (trade name of OHARA INC.). Further, as the second fastening member 26, it is desirable to use a material having a coefficient of thermal expansion as small as possible (absolute value is large) in order to improve the tightening force as the power generation temperature increases. Therefore, it is necessary to set the minimum standard of mechanical strength such as not only the thermal expansion coefficient but also the tensile strength of 1 [Mpa] or more. Furthermore, the initial fastening force at each part where the second fastening member 26 is disposed needs to be set to a reference value or more by managing tension and torque.

  In particular, it is desirable to select the arrangement position of the second fastening member 26 so that the coefficient of thermal expansion is constant with respect to the temperature distribution during power generation at each location of the laminate S. For example, as shown in FIG. 2, the second fastening member 26 made of a material having a low negative thermal expansion coefficient is disposed in the vicinity of both ends of the multilayer body S, and the negative thermal expansion coefficient is present in the central portion of the multilayer body S. The second fastening member 26 made of a high material is disposed. That is, among the second fastening members 26 provided at three locations, the thermal expansion coefficient of the second fastening member 26 is lowered at both ends of the laminated body S, and the thermal expansion coefficient is further increased at both ends of the central portion. To do.

  In this way, in the fuel cell having the property that the central portion of the stacked body S is likely to be high temperature and the both end portions are not likely to be high temperature during power generation, the first and the first results from variations in the temperature distribution of the stacked body S. The fastening force of the two fastening members 25 and 26 can be made uniform at each arrangement location. That is, the gas manifold 23 can be uniformly fastened to the stacked body S regardless of the location of the stacked body S.

  As described above, according to the present embodiment, in order to fix the gas manifold 23 to the outside of the stacked body S, the first fastening member 25 having a positive thermal expansion coefficient and the negative thermal expansion coefficient are used. The first and second fastening members 25, 26 are arranged so as to cover the outer periphery of the gas manifold 23 and the laminated body S in a direction orthogonal to the stacking direction of the unit cells 15. When fastened during power generation (for example, about 60 [° C.] to 100 [° C.]), the first fastening member 25 causes the fastening member to be connected to the unit cell 15 (ie, the fuel cell). The tightening force can be increased. On the other hand, the fastening force of the fastening member to the unit cell 15 can be increased by the second fastening member 26 even when the temperature is stopped or below freezing (for example, about −10 ° C. to 30 ° C.).

  Therefore, the first and second fastening are both performed at a high temperature during start-up of the polymer electrolyte fuel cell 1 or at a low temperature during stoppage (that is, temperature change and temperature deviation of the unit cell 15 that is a fuel cell). It is possible to avoid the occurrence of a gap between the gas manifold 23 and the laminate S due to the looseness of the members 25 and 26, gas leakage due to the occurrence of this gap, and the gas manifold 23 and the laminate S It is possible to prevent peeling of the sealing member provided therebetween.

  In addition, since the occurrence of gas leakage can be prevented in this way, the necessary electric power can be obtained practically sufficiently, and in a fuel cell vehicle equipped with such a polymer electrolyte fuel cell 1, the cruising distance is possible. Can be prevented, and the distance can be sufficiently secured. In particular, there is no possibility of a large amount of hydrogen leaking (4% to 75% of the air capacity), and sufficient safety can be ensured.

 Further, the second fastening member 26 made of a material having a low negative thermal expansion coefficient in the vicinity of both ends of the multilayer body S so that the coefficient of thermal expansion is constant with respect to the temperature distribution during power generation at each location of the multilayer body S. And a second fastening member 26 made of a material having a high negative thermal expansion coefficient in the central portion of the laminated body S, for each tightening portion caused by temperature variation in the unit cell 15 during power generation. Variation in the fastening force can be prevented.

  Since the stacked body S of the unit cell 15 is in contact with the outside air, the temperature of the surface of the stacked body S is lower than that of the central portion. For this reason, when tightening is performed by the second fastening member 26 having the same negative thermal expansion coefficient at all the arrangement positions, the tightening force becomes weaker at both end portions of the laminated body S having a lower temperature. In order to prevent this, the negative thermal expansion coefficient is higher in the central portion where the temperature tends to be higher (absolute value) according to the temperature distribution at each location in the fuel cell stack 2. By disposing the second fastening member 26 having a lower negative thermal expansion coefficient (higher absolute value) at both end portions (that is, the end plates 22 and 22 side) of the laminated body S that is less likely to become higher in temperature. The fastening force for each fastening part can be made more uniform.

  That is, since the fastening force in the second fastening member 26 can be made uniform at each location of the second fastening member 26, the effect of preventing gas leakage in the present invention can be increased.

  Therefore, the gas manifold 23 and the laminated body S can be fixed uniformly at the respective locations of the second fastening member 26, and the occurrence of the gap can be avoided more reliably. That is, it is possible to more reliably prevent gas leakage due to generation of a gap and peeling of the seal member provided between the gas manifold 23 and the stacked body S.

  Further, by using a non-conductive material as the first fastening member 25, a short circuit between the stacked body S of the unit cells 15 and the gas manifold 23 can be prevented.

“Second Embodiment”
FIG. 5, in which the same reference numerals are assigned to the parts corresponding to those in FIG. 2, is a perspective view showing the polymer electrolyte fuel cell 30 according to the second embodiment of the present invention, and the first and second fastening members 25. , 26 is configured in substantially the same manner as the polymer electrolyte fuel cell 1 in the first embodiment, except that the arrangement positions of 26 and 26 are different.

  That is, this polymer electrolyte fuel cell 30 is provided with a non-conductive protective sheet 24 on the outer peripheral surface excluding both ends (that is, the end plates 22 and 22 side) of the laminate S in the fuel cell stack 2, A first fastening member 25 having a positive thermal expansion coefficient and a second fastening member 26 having a negative thermal expansion coefficient so as to cover the outer periphery of the gas manifold 23 and the laminated body S in the stacking direction of the unit cells 15. And are arranged.

  Specifically, the first and second fastening members 25 and 26, each of which is a set of two, are laminated with the laminate S and the gas at approximately one center in the height direction of the laminate S and three equally in the width direction. The manifold 23 was tied to fix the laminated body S, and the gas manifold 23 was fixed to the side surface of the laminated body S. In addition, the number of the 1st and 2nd fastening members 25 and 26 described here is one of the ideal arrangement | positioning examples, and this invention is not limited to this.

  In this manner, by arranging the first and second fastening members 25 and 26, at a high temperature during power generation of the polymer electrolyte fuel cell 30 (for example, about 60 [° C.] to 100 [° C.]), The fastening force between the stacked body S and the gas manifold 23 can be increased by the first fastening member 25 having a positive thermal expansion coefficient. On the other hand, the solid polymer fuel cell 30 is laminated by the second fastening member 26 having a negative coefficient of thermal expansion at a low temperature during power generation or below freezing (for example, about −10 ° C. to 30 ° C.). The tightening force between the body S and the gas manifold 23 can be increased.

  Further, in the case of this embodiment, the first fastening member 25 is in direct contact with the cell 15 as shown in FIG. 5 by using a polymer polyamide resin material as the first fastening member 25. Even if it does not short-circuit, the advantage which can raise fastening force more at low temperature can be acquired.

  As described above, according to the present embodiment, when the gas manifold 23 is fixed to the outside of the stacked body S, the first fastening member 25 having a positive thermal expansion coefficient and the negative thermal expansion coefficient are set. The first and second fastening members 25 and 26 are arranged so as to cover the outer periphery of the gas manifold 23 and the laminated body S in parallel with the stacking direction of the unit cells 15. By fixing, the fastening force of the fastening member to the unit cell 15 (that is, the fuel cell) can be increased by the first fastening member 25 at a high temperature during power generation. On the other hand, the fastening force of the fastening member to the unit cell 15 can be increased by the second fastening member 26 even at a low temperature during the stop or below the freezing point.

  Therefore, in the polymer electrolyte fuel cell 30, the laminate S and the gas manifold are caused by the looseness of the first or second fastening members 25 and 26 both at the high temperature during power generation and at the low temperature during stoppage. It is possible to avoid the occurrence of a gap with respect to 23, and it is possible to avoid gas leakage due to the occurrence of this gap. In addition, since the surface pressure between the single cells 15 (that is, the fuel cells) in the stacked body S can be improved, the electromotive force of the polymer electrolyte fuel cell 30 can also be improved.

  In the case of this embodiment, a polymer polyamide resin material is used as the first fastening member 25, so that even if the first fastening member 25 is in direct contact with the unit cell 15, it is not short-circuited and is low. An advantage that the fastening force can be further increased by the temperature can be obtained.

  Further, by using a non-conductive material as the first fastening member 25, a short circuit between the stacked body S of the unit cells 15 and the gas manifold 23 can be prevented. In addition, when this non-conductive material is made of a polymer or synthetic fiber, the effect of preventing a short circuit between the laminate S and the gas manifold 23 can be maximized.

“Third Embodiment”
FIG. 6, in which the same reference numerals are assigned to the parts corresponding to FIG. 2 and FIG. 5, is a perspective view showing a polymer electrolyte fuel cell 40 according to the third embodiment of the present invention. Except that the arrangement positions of the fastening members 25 and 26 are different, they are configured in substantially the same manner as the polymer electrolyte fuel cells 1 and 30 in the first and second embodiments described above.

  That is, in this polymer electrolyte fuel cell 40, the first and second fastening members are arranged in different directions on the outer peripheral surface excluding both ends (that is, the end plates 22 and 22 side) of the stacked body S in the fuel cell stack 2. The aggregate 27 is formed by weaving alternately (in a so-called lattice pattern), and the aggregate 27 is arranged and fixed so as to cover the entire outer periphery of the gas manifold 23 and the laminate S. At this time, by using a non-conductive material as the first and second fastening members 25 and 26, the aggregate 27 serves as the protective sheet 24 in the first and second embodiments described above. Thereby, the number of parts can be reduced as the whole polymer electrolyte fuel cell.

  Also in this embodiment, as in the first and second embodiments described above, the first fastening member 25 having a positive coefficient of thermal expansion at a high temperature during power generation of the polymer electrolyte fuel cell 40. Thus, the tightening force between the stacked body S and the gas manifold 23 can be increased. On the other hand, when the power of the polymer electrolyte fuel cell 40 is stopped at low temperatures or below freezing point, the fastening force between the stacked body S and the gas manifold 23 is increased by the second fastening member 26 having a negative thermal expansion coefficient. Can do. Therefore, in this polymer electrolyte fuel cell 40, it is possible to avoid the formation of a gap between the laminate S and the gas manifold 23 both at a high temperature during power generation and at a low temperature during a stop. Gas leakage due to generation can be avoided in advance. In addition, since the surface pressure between the single cells 15 (that is, the fuel cells) in the stacked body S can be improved, the electromotive force of the polymer electrolyte fuel cell 30 can also be improved.

  Furthermore, in the case of this embodiment, by using a non-conductive material as the first fastening member 25, a short circuit between the stacked body S of the unit cells 15 and the gas manifold 23 can be prevented. In addition, when this non-conductive material is made of a polymer or synthetic fiber, the effect of preventing a short circuit between the laminate S and the gas manifold 23 can be maximized.

"Other embodiments"
The fuel cell according to the present invention has been described above by taking the above-described embodiment as an example. However, the present invention is not limited to this, and various embodiments can be employed without departing from the gist of the present invention.

  For example, a water-repellent material may be used as the first and second fastening members 25 and 26, or the surfaces of the first and second fastening members 25 and 26 may be subjected to water-repellent processing.

  In this case, it is possible to surely prevent a short circuit from occurring between the unit cell 15 and the gas manifold 23, and to maximize the effect of avoiding leakage due to the adhesion of moisture.

It is a schematic block diagram which shows one Embodiment of the polymer electrolyte fuel cell system to which the fuel cell of this invention is applied. 1 is a perspective view showing a first embodiment of a polymer electrolyte fuel cell according to the present invention. FIG. 3 is a perspective view showing a main part in the polymer electrolyte fuel cell of FIG. 2. FIG. 3 is an enlarged cross-sectional view showing a fuel cell stack in the polymer electrolyte fuel cell of FIG. 2. It is a perspective view which shows 2nd Embodiment of the polymer electrolyte fuel cell by this invention. It is a perspective view which shows 3rd Embodiment of the polymer electrolyte fuel cell by this invention.

Explanation of symbols

1, 30, 40 ... solid polymer fuel cell (fuel cell)
2 ... Fuel cell stack 3 ... Fuel electrode 4 ... Oxidant electrode 15 ... Single cell (unit fuel cell)
16. Solid polymer electrolyte membrane (solid polymer membrane)
DESCRIPTION OF SYMBOLS 17 ... Gas diffusion layer 18 ... Catalyst layer 19 ... Fuel gas flow path 20 ... Oxidant gas flow path 21 ... Separator 22 ... End plate 23 ... Gas manifold 24 ... Protection sheet 25 ... 1st fastening member 26 ... 2nd fastening Member 27 ... Assembly S ... Laminate L ... Rod

Claims (7)

A separator in which a fuel electrode is disposed on one surface of the solid polymer film, an oxidant electrode is disposed on the other surface, and a fuel gas channel is formed on the one surface; and a separator in which an oxidant gas channel is formed on the other surface; A fuel cell comprising a gas manifold outside a laminate formed by laminating a plurality of unit fuel cells that receive power from the fuel gas and the oxidant gas to generate power,
The gas manifold and the laminate are
A first fastening member having a positive coefficient of thermal expansion and a second coefficient having a negative coefficient of thermal expansion so as to cover the gas manifold and the outer periphery of the stack in a direction orthogonal to the stacking direction of the unit fuel cells. A fuel cell characterized by being fastened and fixed by a fastening member. A separator in which a fuel electrode is disposed on one surface of the solid polymer film, an oxidant electrode is disposed on the other surface, and a fuel gas channel is formed on the one surface; and a separator in which an oxidant gas channel is formed on the other surface; A fuel cell comprising a gas manifold outside a laminate formed by laminating a plurality of unit fuel cells that receive power from the fuel gas and the oxidant gas to generate power,
The gas manifold and the laminate are
A first fastening member having a positive thermal expansion coefficient and a second fastening member having a negative thermal expansion coefficient so as to cover the gas manifold and the outer periphery of the stack in the stacking direction of the unit fuel cells; A fuel cell characterized by being fastened and fixed with The fuel cell according to claim 1 or 2, wherein
A fastening member including one set of the first and second fastening members is disposed at least in the vicinity of both ends and the substantially central portion of the laminate, and the second fastening member of the central portion The fuel cell, wherein the negative thermal expansion coefficient is larger than that of the second fastening member at both ends. The fuel cell according to claim 1 or 2, wherein
The fuel cell, wherein the first and second fastening members are made of a non-conductive material. The fuel cell according to claim 4, wherein
The fuel cell, wherein the non-conductive material used for the first and second fastening members is made of a polymer or a synthetic fiber. A fuel cell according to claim 4 or claim 5, wherein
The fuel is characterized in that the first and second fastening members are alternately arranged in different directions to form an assembly, and the assembly is disposed so as to cover the entire outer periphery of the gas manifold and the laminate. battery. A fuel cell according to any one of claims 4 to 6, comprising:
The fuel cell, wherein the first and second fastening members have water repellency.

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