JP2019133894A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell which reduces a load applied to a cell stack when the fuel cell is disassembled. An end plate 11 having an area larger than the area of the cell stack 9 when viewed in the insertion direction is provided at a position facing a bottom part 26b of the cell stack 9. A tapered surface 11s is provided which is tapered in the direction opposite to the side. [Selection diagram] Fig. 5

Description

  The present invention relates to a fuel cell.

  For example, a polymer electrolyte fuel cell (sometimes referred to as a fuel cell, a single cell, or a single cell) includes an ion-permeable electrolyte membrane, an anode-side catalyst layer (electrode layer) that sandwiches the electrolyte membrane, and A membrane electrode assembly (MEA) comprising a cathode catalyst layer (electrode layer) is provided. On both sides of the MEA, a gas diffusion layer (GDL) is provided for supplying fuel gas or oxidant gas and collecting electricity generated by an electrochemical reaction. The MEA in which the GDL is arranged on both sides is referred to as MEGA (Membrane Electrode & Gas Diffusion Layer Assembly), and the MEGA is sandwiched between a pair of separators. Here, when the MEGA is a power generation part of the fuel cell and there is no gas diffusion layer, the MEA becomes the power generation part of the fuel cell.

  A fuel cell (sometimes referred to as a fuel cell stack) is formed by stacking a plurality of cells having the structure as described above, and a pair of end plates (pressure plates) outside the cells located at both ends of the cell stack. Or a terminal plate, a fastening plate, etc.), the cell stack is pressed and fastened with a pair of end plates, and the pressed and fastened cell stack (hereinafter sometimes referred to as a fuel cell body) Is housed in a stack case.

  In this type of fuel cell, in recent years, for example, in order to prevent displacement of cells constituting the fuel cell body (cell displacement) while improving vibration resistance and impact resistance, An elastic material such as silicon rubber or urethane rubber is interposed as an intervening layer (hereinafter sometimes referred to as a filling) between the stack case and the fuel cell main body. A restraint is proposed.

  Further, in the fuel cell having the intervening layer between the fuel cell main body and the stack case as described above, for example, the intervening layer is disposed on the side surface of the fuel cell main body (cell stack), and then the intervening layer is crushed. It is manufactured by a method of inserting a fuel cell main body into a stack case (see, for example, Patent Document 1 below).

JP 2006-012408 A

  By the way, in this type of fuel cell, an end plate having a larger area in the plane direction (projected area when viewed in the stacking direction) than the cell stack is used as an end plate for pressurizing and sandwiching the cell stack. May be provided. Also, due to manufacturing requirements and the like, unlike the one described in Patent Document 1, it is assumed that a filling (intervening layer) is pasted on the inner surface of the stack case in advance. In this case, when the fuel cell is disassembled, the end plate may be caught by the filling and a large stress may be applied to the cell stack.

  This invention is made | formed in view of the said subject, The place made into the objective is to provide the fuel cell which reduces the load added to a cell laminated body at the time of decomposition | disassembly of a fuel cell.

  In order to solve the above problems, a fuel cell according to the present invention includes a cylindrical stack case having a bottom, a cell stack inserted into the stack case, and an inner peripheral surface of the stack case. And a filling for pressurizing the cell stack inserted into the cell stack, and an end plate larger in area when viewed in the insertion direction than the cell stack is provided at a position facing the bottom of the cell stack. The end plate is provided with a tapered surface that tapers in a direction opposite to the bottom side on the outer peripheral end surface of the end plate.

  According to the present invention, the cell stack can be pulled out from the stack case while the filling for pressurizing the cell stack is gradually crushed by the taper surface provided on the outer peripheral end surface of the end plate. The load applied to the body can be reduced.

1 is a cross-sectional view of one embodiment of a combustion battery according to the present invention. It is principal part sectional drawing of the fuel cell (fuel cell stack) shown by FIG. FIG. 2 is an exploded perspective view of the fuel cell shown in FIG. 1. It is a principal part expanded sectional view at the time of manufacture of the fuel cell shown by FIG. FIG. 2 is an enlarged cross-sectional view of a main part when the fuel cell shown in FIG. 1 is disassembled.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings. Hereinafter, as an example, a case where the present invention is applied to a fuel cell mounted on a fuel cell vehicle or a fuel cell system including the fuel cell will be described as an example. However, the scope of application is not limited to such an example. .

[Configuration of fuel cell (fuel cell stack)]
FIG. 1 is a cross-sectional view of an embodiment of a combustion battery according to the present invention. FIG. 2 is a cross-sectional view of the main part of the fuel cell (fuel cell stack) shown in FIG.

  The fuel cell 100 of the illustrated embodiment basically includes a fuel cell main body 10, a stack case 25 that accommodates the fuel cell main body 10 inside, and an interposition disposed between the fuel cell main body 10 and the stack case 25. And a filling 30 as a layer.

  First, taking a solid polymer fuel cell as an example of the fuel cell (fuel cell stack) 100 according to the present invention, the internal configuration thereof will be outlined with reference to FIG.

  FIG. 2 is a cross-sectional view of the main part of the fuel cell main body 10 of the fuel cell (fuel cell stack) 100. As shown in FIG. 2, a plurality of cells (unit cells) 1 that are basic units are stacked in a fuel cell body 10 (cell stack 9). Each cell 1 is a polymer electrolyte fuel cell that generates an electromotive force by an electrochemical reaction between an oxidant gas (for example, air) and a fuel gas (for example, hydrogen). The cell 1 includes a MEGA 2 and a separator (fuel cell separator) 3 that contacts the MEGA 2 so as to partition the MEGA 2. In the present embodiment, the MEGA 2 is sandwiched between a pair of separators 3 and 3.

  The MEGA 2 is obtained by integrating a membrane electrode assembly (MEA) 4 and gas diffusion layers 7 and 7 disposed on both sides thereof. The membrane electrode assembly 4 includes an electrolyte membrane 5 and a pair of electrodes 6 and 6 joined so as to sandwich the electrolyte membrane 5. The electrolyte membrane 5 is made of a proton-conductive ion exchange membrane made of a solid polymer material, and the electrode 6 is made of, for example, a porous carbon material carrying a catalyst such as platinum. The electrode 6 disposed on one side of the electrolyte membrane 5 is an anode, and the electrode 6 on the other side is a cathode. The gas diffusion layer 7 is formed of a conductive member having gas permeability, such as a carbon porous body such as carbon paper or carbon cloth, or a metal porous body such as a metal mesh or foam metal.

  In the present embodiment, the MEGA 2 is a power generation unit of the fuel cell 100 (the fuel cell main body 10 thereof), and the separator 3 is in contact with the gas diffusion layer 7 of the MEGA 2. When the gas diffusion layer 7 is omitted, the membrane electrode assembly 4 is a power generation unit, and in this case, the separator 3 is in contact with the membrane electrode assembly 4. Therefore, the power generation unit of the fuel cell 100 (the fuel cell main body 10 thereof) includes the membrane electrode assembly 4 and contacts the separator 3.

  The separator 3 is a plate-like member based on a metal having excellent conductivity and gas impermeability, and one side of the separator 3 is in contact with the gas diffusion layer 7 of the MEGA 2 and the other side is adjacent to another separator. 3 is in contact with the other surface side.

  In this embodiment, each separator 3 is formed in a wave shape or an uneven shape. The shape of the separator 3 is such that the wave shape is an isosceles trapezoid and the top of the wave is flat, and both ends of the top are angular with equal angles. That is, each separator 3 has substantially the same shape when viewed from the front side and from the back side. The top of the separator 3 is in surface contact with one gas diffusion layer 7 of the MEGA 2, and the top of the separator 3 is in surface contact with the other gas diffusion layer 7 of the MEGA 2.

  The gas flow path 21 defined between the gas diffusion layer 7 on the one electrode (ie, anode) 6 side and the separator 3 is a flow path through which the fuel gas flows, and the other electrode (ie, cathode) 6 side. The gas flow path 22 defined between the gas diffusion layer 7 and the separator 3 is a flow path through which the oxidant gas flows. When the fuel gas is supplied to one gas flow path 21 facing through the cell 1 and the oxidant gas is supplied to the gas flow path 22, an electrochemical reaction occurs in the cell 1 to generate an electromotive force.

  Further, a certain cell 1 and another cell 1 adjacent thereto are arranged such that an electrode 6 serving as an anode and an electrode 6 serving as a cathode face each other. Further, the top on the back side of the separator 3 disposed along the electrode 6 serving as the anode of a certain cell 1 and the top of the back side of the separator 3 disposed along the electrode 6 serving as the cathode of another cell 1. Are in surface contact. In a space 23 defined between the separators 3 and 3 in surface contact between two adjacent cells 1, water as a coolant for cooling the cells 1 flows.

  In addition, a gasket (not shown) as a sealing member that seals fuel gas (for example, hydrogen) or oxidant gas (for example, air) or cooling water is held between the ends of two adjacent cells 1. Has been.

  As shown in FIG. 1, the fuel cell main body 10 mainly includes the cell stack 9 and a pair of end plates 11 and 12.

  The pair of end plates 11 and 12 are disposed outside the cell 1 located at both ends (both ends in the cell stacking direction) of the cell stack 9, and the fuel cell main body 10 includes the cell stack 9 and the pair of end plates 11, 12. 12 is sandwiched (restrained) at a predetermined surface pressure, and a load in the stacking direction is applied (applied) with a restraining member made of a tension plate (not shown) arranged so as to connect the end plates 11 and 12 to each other. Pressure) and fastened. The tension plate that restrains the cell stack 9 and the like in a stacked state is provided so as to bridge between the end plates 11 and 12. For example, a pair is opposed to both sides of the fuel cell main body 10. Be placed. The tension plate is connected to each end plate 11, 12 and maintains a state in which a predetermined fastening force (compression load) is applied in the stacking direction of the cell stack 9.

  In this example, the end plate 11 disposed on the insertion side to the stack case 25 (position facing the bottom portion 26b of the stack case 25) in the direction perpendicular to the cell stacking direction (insertion direction to the stack case 25 described later). Is larger than the maximum width of the cell stack 9, and the area (outer shape) of the end plate 11 when viewed in the insertion direction is designed to be larger than the area (outer shape) of the cell stack 9. Further, the outer periphery of the end portion of the end plate 11 on the insertion side into the stack case 25 (in other words, the bottom portion 26b side of the stack case 25 on the outer peripheral end surface 11a of the end plate 11), the tip end side (insertion direction into the stack case 25). ) Is provided with a tapered surface 11t that is tapered (narrow) toward the cell stack 9 side on the outer peripheral end surface 11a of the end plate 11, and is tapered in the direction opposite to the bottom 26b side ( A tapered surface 11s made of a truncated cone surface having a narrow width is provided (detailed later).

  The stack case 25 includes a case body 26 and a lid body 27. In this example, a lid 27 is integrally formed on the end plate 12 disposed on the opposite side of the pair of end plates 11 from the side inserted into the stack case 25. In other words, the end plate 12 also serves as the lid 27.

  The case body 26 has a rectangular tube shape with a bottom portion 26b that is open at one end. Specifically, it has a substantially rectangular or box-like appearance having a gap for accommodating the fuel cell body 10 inside, and one surface constituting the case body 26 is an opening (insertion opening) 26a. 26a is closed and sealed with a lid 27 integrated with the end plate 12, and the fuel cell body 10 is accommodated in a compressed state.

  The filling 30 is disposed between the side surface (outer peripheral surface) along the cell stacking direction in the fuel cell main body 10 (the cell stack 9) and the inner peripheral surface of the stack case 25 (the side wall of the case main body 26). Yes.

  In this example, the filling 30 has, for example, a substantially rectangular shape, and when viewed in a cross section in the cell stacking direction (the cross section shown in FIG. 1), the side surface of the fuel cell body 10 (the side surface along the cell stacking direction). ) And a plurality of (three in the illustrated example) at intervals along the side surface (side surface along the cell stacking direction) of the fuel cell body 10. ) Are arranged separately. In this way, by providing two or more fillings 30 so as to face each other, shear strain and rotational moment acting on the fuel cell main body 10 (cell stack 9 thereof) can be suppressed.

  If the filling 30 is disposed at a position facing the inner peripheral surface of the stack case 25 (the side wall of the case body 26), the shape, size, placement location, and the like are limited to the illustrated example. Of course not. For example, when viewed in a cross section in the cell stacking direction, the fuel cell main body 10 may be arranged from one end to the other end of the side surface along the cell stacking direction (that is, continuously without any interval). .

  The filling 30 is formed of a flexible and insulating elastic material such as silicon rubber or urethane rubber, and is attached to the opposing inner peripheral surface of the stack case 25 (the side wall of the case body 26). In a state before the main body 10 is accommodated (inserted) in the stack case 25 (that is, in a state where the load with respect to the filling 30 is zero), the minimum distance between the opposing fillings 30 is the fuel cell main body facing the filling 30. It is designed to be smaller than the maximum width of ten cell stacks 9. When the fuel cell body 10 is accommodated (inserted) in the stack case 25, the filling 30 is elastically compressed and deformed (collapsed) by the fuel cell body 10 (end plate 11 thereof) (see FIG. 4). The filling 30 is elastically expanded (in other words, due to its restoring force) to fill the gap between the fuel cell main body 10 according to the unevenness of each cell 1 of the fuel cell main body 10, and the side surface of the fuel cell main body 10. Narrow pressure is held in a compressed state between the inner peripheral surface of the stack case 25 (the side wall of the case body 26). Due to the elasticity of the filling 30, the cell stack 9 of the fuel cell main body 10 is restrained by the stack case 25, and vibration resistance and impact resistance are improved. In addition, the displacement of the cells 1 constituting the fuel cell main body 10 (particularly, , Positional deviation in a direction perpendicular to the stacking direction) is suppressed.

  The filling 30 may be sealed in a bag made of polypropylene or the like and cured inside the bag after filling to exhibit the above-described restraining function or the like.

[Manufacturing method and disassembling method of fuel cell (fuel cell stack)]
In manufacturing the above-described fuel cell (fuel cell stack) 100, first, a plurality of the cells 1 described above are stacked at a predetermined interval (for example, about 2 mm pitch), and a seal is used between two adjacent cells 1 The cell laminate 9 is formed by arranging the gaskets.

  Next, the pair of end plates 11 and 12 are disposed outside the cell 1 located at both ends of the cell stack 9, and the cell stack 9 is attached using the end plates 11 and 12 and a tension plate. Pressurize (apply a load) in the stacking direction (of cell 1), compressively deform gas diffusion layers 7 and 7 of each cell 1, and change the interval between cells 1 (for example, from about 2 mm pitch to about 1 mm pitch) The fuel cell body 10 is formed by narrowing.

  Next, a case main body 26 in which the above-described filling 30 is arranged and fixed (for example, by bonding) is prepared, and the fuel cell main body 10 pressed and held by the end plates 11 and 12 and the tension plate is used as the end plate. 11 (the taper surface 11t) side through the opening (insertion opening) 26a of the case body 26 (see FIG. 3), and the lid 27 integrated with the end plate 12 is inserted into the opening 26a of the case body 26. The fuel cell body 10 is sealed in the stack case 25 by fastening.

  Here, as described above, in the state before the fuel cell body 10 is inserted into the stack case 25, the minimum interval between the fillings 30 attached to the inner peripheral surfaces facing each other of the stack case 25, Since the end plate 11 and the width of the end plate 11 are designed to increase in that order, when the fuel cell main body 10 is inserted (pushed) into the case main body 26 of the stack case 25, the tapered surface of the end plate 11 ( 11t) contacts the filling 30 and the fuel cell main body 10 is inserted into the case main body 26 while the filling 30 is crushed (compressed and elastically deformed) (see FIG. 4). After the end plate 11 (the tapered surface 11t) passes while crushing the filling 30, the filling 30 is gradually expanded by its restoring force (elastic force) and then returns to the initial thickness, but the initial thickness is restored. Without being compressed, the fuel cell body 10 is disposed between the side surface of the fuel cell main body 10 (the cell stack 9) and the inner peripheral surface of the stack case 25 (the side wall of the case main body 26).

  As a result, the fuel cell 100 provided with the cell-constrained filling 30 is manufactured.

  In disassembling the fuel cell (fuel cell stack) 100, the lid 27 is unfastened and the fuel cell main body 10 is pulled out through the opening (insertion opening) 26a of the case main body 26. At this time, a taper surface (taper surface provided on the cell laminate 9 side opposite to the bottom 26b side) 11s provided on the outer peripheral end surface 11a of the end plate 11 abuts on the filling 30 (in a compressed state), The fuel cell body 10 is taken out from the case body 26 while the filling 30 is crushed (see FIG. 5).

  In this case, the feed speed at the time of insertion into the stack case 25 (the case body 26) is determined by the cycle time of the process, but the feed speed at the time of disassembly is not particularly limited, so the ( The taper angle θs (with respect to the cell stacking direction) can be set larger than the taper angle θt (with respect to the cell stacking direction (insertion direction)) of the tapered surface 11t. For example, the taper angle θs can be set larger than the taper angle θt and not more than 45 ° (particularly, refer to FIGS. 4 and 5).

  As described above, in the present embodiment, the cells 30 of the fuel cell main body 10 are gradually crushed by the tapered surface 11s provided on the outer peripheral end surface 11a of the end plate 11 while gradually crushing the filling 30 that pressurizes the cell stack 9 of the fuel cell main body 10. The stack 9 can be pulled out from the stack case 25, and the load applied to the cell stack 9 of the fuel cell body 10 can be reduced by avoiding the catching between the filling 30 and the end plate 11 when the fuel cell 100 is disassembled. .

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Cell (fuel cell), 2 ... MEGA, 3 ... Separator, 4 ... Membrane electrode assembly (MEA), 5 ... Electrolyte membrane, 6 ... Electrode, 7 ... Gas diffusion layer, 8 ... Gasket, 9 ... Cell lamination 10, fuel cell main body, 11, end plate (insertion side, bottom side), 11 a, outer peripheral end surface, 11 s, taper surface (on the side opposite to the insertion side and bottom side), 11 t, taper surface (insertion side, bottom portion) Side), 12 ... end plate (insertion side, opposite to the bottom side), 21, 22 ... gas flow path, 23 ... space through which water flows, 25 ... stack case, 26 ... case body, 26a ... opening (insertion) Opening), 26b ... bottom, 27 ... lid, 30 ... filling, 100 ... fuel cell (fuel cell stack)

Claims (1)

A cylindrical stack case having a bottom, and
A cell stack inserted into the stack case;
A filling provided on the inner peripheral surface of the stack case and pressurizing the cell stack inserted into the stack case,
At a position facing the bottom of the cell stack, an end plate larger in area when viewed in the insertion direction than the cell stack is provided,
A fuel cell in which an outer peripheral end surface of the end plate is provided with a tapered surface that tapers in a direction opposite to the bottom side.

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