JP6696852B2 - Fuel cell - Google Patents

Description

  The present invention relates to fuel cells.

  For example, a polymer electrolyte fuel cell (hereinafter referred to as a fuel cell) has a structure in which a plurality of single cells (hereinafter also referred to as cells) having a power generation function are stacked. The unit cell has a membrane electrode assembly (MEA) in which a pair of (anode, cathode) catalyst layers are arranged at both ends of a polymer electrolyte membrane, and a pair of separators sandwiching the membrane electrode assembly. A fuel cell is usually mounted in, for example, a fuel cell vehicle as a fuel cell stack in which a plurality of cells are stacked.

  When used in a vehicle, the fuel cell stack is apt to be subject to external loads in addition to shaking and vibration. In addition, it is necessary to reliably protect the fuel cell stack in the event of a vehicle collision. Therefore, a structure for protecting the fuel cell stack has been proposed, for example, as disclosed in Patent Document 1 below.

  Patent Document 1 below discloses a fuel cell in which a laminated body in which a plurality of cells are laminated is housed in a case, and the laminated body and the case are connected by a pair of connecting bars. The pair of connecting bars is arranged between the case and the stacked body, and is located on the substantially center side of the side surface along the cell stacking direction of the stacked body (direction in which cells are stacked). According to the following Patent Document 1 which discloses such a connecting bar, it is said that the fuel cell stack can be reliably protected with a simple and economical structure.

JP, 2015-225809, A

  By the way, the displacement between the cells of the stacked body is likely to occur in the direction perpendicular to the cell stacking direction. The cause of this shift is due to the occurrence of a swinging moment centered on the center of gravity of the cell when viewed in a cross section perpendicular to the cell stacking direction when vibration is applied to the fuel cell stack. In the fuel cell of the above-mentioned Patent Document 1, a connecting bar (impact protector) is provided between the case and the cell stack to protect the fuel cell stack, but the swinging moment described above is not considered at all. However, there is a possibility that a shift between cells may occur.

  The present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell capable of suppressing the occurrence of the displacement between the cells of the stacked body.

  In order to solve the above problems, the fuel cell according to the present invention is a fuel cell including a cell stack in which a plurality of rectangular cells are stacked, and a case that houses the cell stack, wherein A first impact protector and a second impact protector are disposed between a side surface along the cell stacking direction and the case, wherein the first impact protector and the second impact protector are in the cell stacking direction. When viewed in a cross section perpendicular to, the cells are arranged with the corners of the cell sandwiched therebetween, pass through the first impact protector, and extend in a direction along one side of the cell where the first impact protector is disposed. The distance between the first extension line extending in the direction perpendicular to the first line and the first extension line extending through the center of gravity of the cell in the direction perpendicular to the direction along the one side is defined as a, and the second line A second extension line that passes through the impact protector and extends in a direction perpendicular to the direction along the other side of the cell in which the second impact protector is disposed, and passes through the center of gravity of the cell and extends along the other side. The elastic modulus Ea of the first impact protector and the elastic modulus Eb of the second impact protector when the distance between the second center of gravity extension line extending in the direction perpendicular to the direction is defined as b. The elastic modulus ratio satisfies the relationship of Ea / Eb = b / a.

  In the fuel cell according to the present invention, the elastic modulus of the first impact and the elastic modulus of the second impact protector are set so as to satisfy the relationship of Ea / Eb = b / a. As a result, when viewed in a cross section perpendicular to the cell stacking direction, the swinging moments in the opposite directions generated around the center of gravity of the cell can be set to the same value, and the swinging moments in the opposite directions cancel each other out. It will be. As a result, the swing of the cell stack is suppressed, and it is possible to suppress the occurrence of displacement between the unit cells of the cell stack.

  According to the present invention, it is possible to provide a fuel cell capable of suppressing the occurrence of displacement between cells of a laminated body.

It is a schematic sectional drawing which shows the cross section along the cell stacking direction of the fuel cell stack which concerns on this embodiment. It is an AA sectional view of FIG. (A) It is a figure for demonstrating the fuel cell stack which concerns on a 1st modification. (B) It is a figure for demonstrating the fuel cell stack which concerns on a 2nd modification. (A) is a graph showing the relationship between the elastic modulus and hardness of the impact protector and the impact reaction force. (B) is a graph showing the relationship between the thickness and precompression rate of the impact protector and the impact reaction force.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the following description of the preferred embodiments is merely an example, and is not intended to limit the present invention, its application, or its use.

  First, the configuration of the fuel cell according to the embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing a cross section along a cell stacking direction of a fuel cell stack (fuel cell) according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and shows a cross section perpendicular to the cell stacking direction (a cross section along a unit cell having a flat plate shape) in the vicinity of substantially the center of a fuel cell stack having a substantially rectangular parallelepiped shape as a whole. ) Is shown.

  The fuel cell stack 1 generates electric power by the electrochemical reaction between the fuel gas and the oxidant gas. As shown in FIG. 1, the fuel cell stack 1 includes a cell stack body 2 in which a plurality of rectangular unit cells 20 are stacked, a case 3, a first impact protector 4, and a second impact protector 5. Equipped with.

  The unit cell 20 (see FIG. 2) is configured by sandwiching a membrane electrode assembly formed by joining an anode and a cathode on both sides of an electrolyte membrane having proton conductivity with separators. The number of stacked membrane electrode assemblies in the fuel cell stack 1 can be arbitrarily set according to the output required for the fuel cell stack 1. The plurality of unit cells 20 are stacked along the cell stacking direction S (FIG. 1) to form the cell stack 2.

  The case 3 is a substantially rectangular parallelepiped-shaped container and houses at least the cell stack body 2, the first impact protection body 4, and the second impact protection body 5. The case 3 is provided so as to cover the cell stack 2 with a predetermined gap left between the case 3 and the cell stack 2.

  An impact protector (first impact protector 4 and second impact protector 5) is arranged between the case 3 and the side surface of the cell stack 2 along the cell stacking direction S. When viewed in a cross section perpendicular to the cell stacking direction S, the first impact protector 4 and the second impact protector 5 are arranged so as to sandwich the corner portion 20c of the single cell 20 therebetween as shown in FIG. Has been done.

  The first impact protector 4 extends in the cell stacking direction S along a side surface (shorter surface 2A shown in FIG. 1) on the short side of the side surfaces of the cell stack 2 having a substantially rectangular cross section along the cell stacking direction S. It is extended and arranged. When viewed in a cross section perpendicular to the cell stacking direction S, as shown in FIG. 2, the first impact protector 4 has both ends of the short side 20a of the unit cell 20 (in other words, the corner portion 20c of the unit cell 20). It is located in the vicinity). In this embodiment, the first impact protection body 4 is composed of a rod-shaped member having a substantially rectangular cross section. However, the first impact protector 4 in the present embodiment is not limited to this example, and the first impact protector 4 in the present embodiment may have a shape, number, and the like as long as it has a function of suppressing the occurrence of displacement between the single cells 20 of the cell stack 2. Can be changed as appropriate.

  The second impact protector 5 is arranged so as to extend in the cell stacking direction S along the long side surface (long surface 2B shown in FIG. 1) of the side surfaces of the cell stack 2 along the cell stacking direction S. To be done. When viewed in a cross section perpendicular to the cell stacking direction S, as shown in FIG. 2, the second impact protector 5 has both ends of the long side 20b of the unit cell 20 (in other words, the corner portion 20c of the unit cell 20). It is located in the vicinity). In the present embodiment, the second impact protection body 5 is composed of a rod-shaped member having a substantially square cross section. However, the present invention is not limited to this example, and the second impact protector 5 in the present embodiment may have any shape or number as long as it has a function capable of suppressing the occurrence of displacement between the unit cells 20 of the cell stack 2. And the like can be changed as appropriate.

  By the way, the displacement between the unit cells 20 of the cell stack 2 is likely to occur in the direction perpendicular to the cell stacking direction S (see FIG. 1) (the vertical direction (arrow P direction in FIG. 2)). The arrow P in FIG. 2 indicates the direction in which the impact acceleration of vibration is applied. When impact acceleration due to vibration is applied in the direction of arrow P in FIG. 2, the first impact protection body 4 and the second impact protection body 5 receive the impact acceleration, and the impact reaction forces Fa and Fb and the associated swing moments Ma and Mb. (The swing moments Ma and Mb are expressed as Ma = Fa × a and Mb = Fb × b by using the distances a and b shown in FIG. 2. Details of the distances a and b will be described later). The swinging moment Ma and the swinging moment Mb are in mutually opposite rotational directions, and when the magnitudes of these swinging moments are different, a deviation may occur between the unit cells 20 of the cell stack 2. That is, in order to suppress the occurrence of displacement between the unit cells 20 of the cell stack 2 in the fuel cell stack 1, it is preferable to suppress the swinging moment.

  Therefore, as a method of suppressing the swinging moment, by making the elastic moduli of a plurality of impact protectors arranged between the case 3 and the cell stack 2 the same, the strength of the impact protector can be increased ( There is an idea to suppress the swinging moment by increasing the thickness. However, in this method, since the thickness of the impact protector is increased, there is a problem that the size of the fuel cell stack is increased. When the thickness of the impact protector is reduced in order to solve the problem that the physical size of the fuel cell stack becomes large, if the impact protectors have the same elastic modulus, the swinging moment cannot be suppressed. I will end up.

In view of the above, the inventors of the present invention have conducted various experiments, and as a result, by setting the elastic modulus of the impact protector as described below, it was found that the swing moment can be suppressed while reducing the thickness of the impact protector. I found it. Based on this finding, in the present embodiment, the ratio of the elastic modulus Ea of the first impact protector 4 and the elastic modulus Eb of the second impact protector 5 is the distance a and the distance b shown in FIG. It is set so as to satisfy the relationship of the following expression (1).
Ea / Eb = b / a (1)
(B / a≈ (width Db of long side 20b) / (width Da of short side 20a))

  The distance a in the above equation (1) is set as follows. That is, when viewed in a cross section perpendicular to the cell stacking direction shown in FIG. 2, one side of the unit cell 20 on which the first shock protector 4 is arranged (the short side 20a shown in FIG. 2) passes through the first shock protector 4. ) With a first extension line L1 extending in a direction perpendicular to the direction, and a first centroid extension line L1g passing through the center of gravity G of the unit cell 20 and extending in a direction perpendicular to the direction along the short side 20a. The distance between them is set as the distance a.

  The distance b in the above equation (1) is set as follows. That is, when viewed in a cross section perpendicular to the cell stacking direction shown in FIG. 2, the other side of the single cell 20 on which the second shock protector 5 is arranged (the long side shown in FIG. 2) passes through the second shock protector 5. 20b) and a second extension line L2 extending in a direction perpendicular to the direction, and a second center-of-gravity extension line L2g passing through the center of gravity G of the unit cell 20 and extending in a direction perpendicular to the direction along the long side 20b. The distance between them is set as the distance b.

  As described above, in the present embodiment, the elastic moduli of the first impact protection body 4 and the elastic moduli of the second impact protection body 5 are set based on the relationship shown in the above equation (1). As a result, the swinging moments (Ma, Mb) in the opposite directions generated around the center of gravity G of the unit cell 20 shown in FIG. 2 can be set to the same value, and the swinging moments in the opposite directions cancel each other. Becomes Therefore, the swing of the cell stack 2 is suppressed, and the occurrence of the displacement between the unit cells 20 of the cell stack 2 can be suppressed.

  A plurality of communication holes 30 communicating with each other in the cell stacking direction are formed at both ends of the fuel cell stack 1 in the long side direction (left and right direction in FIG. 2). The three communication holes 30 on one side of the both ends constitute one of an oxidant gas supply communication hole, a fuel gas supply communication hole, and a cooling medium supply communication hole. The oxidant gas supply communication hole supplies an oxidant gas (for example, an oxygen-containing gas), the fuel gas supply communication hole supplies a fuel gas (for example, a hydrogen-containing gas), and the cooling medium supply communication hole serves as a cooling medium. To supply. The three communication holes 30 on the other side of both ends constitute any one of an oxidant gas discharge communication hole, a fuel gas discharge communication hole, and a cooling medium discharge communication hole. The oxidant gas discharge communication hole is for discharging the oxidant gas, the fuel gas discharge communication hole is for discharging the fuel gas, and the cooling medium discharge communication hole is for discharging the cooling medium. belongs to.

  Next, a modified example will be described. FIG. 3A shows a cross section perpendicular to the cell stacking direction of the fuel cell stack in the first modification. FIG. 3B shows a cross section perpendicular to the cell stacking direction of the fuel cell stack in the second modification. The fuel cell stack according to the modified example shown in FIG. 3 is obtained by changing the numbers and shapes of the first impact protector and the second impact protector shown in FIGS. 1 and 2, and has other configurations and functions. Is the same. Therefore, description of the same parts as those already described will be omitted.

  In the fuel cell stack 1 according to the first modification, as shown in FIG. 3A, the first impact protector 4 and the second impact protector 5 are arranged along the long side 20b and the short side 20a of the unit cell 20. It is arranged intermittently. Specifically, when viewed in a cross section perpendicular to the cell stacking direction, the first impact protector 4 is arranged on both end sides of the short side 20a of the single cell 20 (in other words, in the vicinity of the corner 20c). , One on the center side of the short side 20a, that is, six in total. The second impact protector 5 is arranged on both ends of the long side 20b of the single cell 20 (in other words, near the corner 20c), and one second shock protector 5 is arranged on the center side of the long side 20b of the single cell 20, that is, in total. Six are arranged.

  In the fuel cell stack 1 of the second modified example, the thickness ta of the first impact protection body 4 and the thickness tb of the second impact protection body 5 are different. For example, as shown in FIG. 3B, the thickness ta of the first impact protector 4 is set to be smaller than the thickness tb of the second impact protector 5 so that a larger impact reaction force is generated in the first impact protector 4. It is also preferable to make it thinner. The thickness ta of the first impact protection body 4 is the size of the first impact protection body 4 in the thickness direction (left and right direction in FIG. 3) when viewed in a cross section perpendicular to the cell stacking direction ( Means width). The thickness tb of the second impact protection body 5 refers to the size (width) in the thickness direction (vertical direction in FIG. 3) of the second impact protection body 5 when viewed in a cross section perpendicular to the cell stacking direction. Means

  In the present embodiment described above, each of the first impact protector 4 and the second impact protector 5 is arranged so as to sandwich the four corners 20c of the unit cell 20, as shown in FIG. (In other words, four first impact protectors 4 near the corners 20c and four second impact protectors 5 near the corners 20c) are not limited to this example. For example, the first shock protector 4 and the second shock protector 5 may be arranged only in the vicinity of a pair of opposite corners of the unit cell 20 (that is, in the vicinity of two corners 20c). In this case, two first impact protectors 4 and two second impact protectors 5 are arranged. In addition, as long as it has the functions of the first impact protector 4 and the second impact protector 5, the number and shape of the first impact protector 4 and the second impact protector 5 can be appropriately changed. Is.

As another modified example, the ratio of the hardness Ka of the material of the first impact protector 4 to the hardness Kb of the material of the second impact protector is expressed by the following equation when the distance a and the distance b shown in FIG. You may set so that the relationship of (2) may be satisfy | filled (refer FIG. 4 (A)).
Ka / Kb = b / a (2)

Further, the precompression rate Ra when the first impact protection body 4 is housed in the case 3 and the precompression rate Rb when the second impact protection body 5 is housed in the case 3 may be different. The precompression rate is a value obtained by dividing the deformation amount Δt of the thickness of the protective body due to precompression by the thickness t before precompression. Assuming the impact reaction forces Fa and Fb (see FIG. 2) generated when the impact acceleration due to vibration is applied to the fuel cell stack, the relationship between the impact reaction forces Fa and Fb and the precompression rates Ra and Rb is shown. , May be set based on the relationship shown in FIG. More specifically, when the lateral elastic modulus of the first impact protector 4 and the second impact protector 5 is G, the relationship between the precompression rate Ra and the impact reaction force Fa is Fa = G {(Ra-1) + 1 / (Ra-1) ² }, the relationship between the precompression rate Rb and the impact reaction force Fb is Fb = G {(Rb-1) + 1 / (Rb-1) ² }. Therefore, when the distances a and b shown in FIG. 2 are used, the precompression rates Ra and Rb are set so as to satisfy the relationship of the following expression (3).
{(Ra-1) + 1 / (Ra-1) ² } / {(Rb-1) + 1 / (Rb-1
) ² } = b / a (3)

When the thickness ta of the first impact protection body 4 before precompression is different from the thickness tb of the second impact protection body 5 before precompression, the following settings may be made. It is suitable. That is, assuming the impact reaction forces Fa and Fb (see FIG. 2) generated when the impact acceleration due to vibration is applied to the fuel cell stack, the impact reaction forces Fa and Fb and the reciprocal 1 / ta of the thickness, It is preferable to set the relationship with 1 / tb based on the relationship shown in FIG. More specifically, regarding the first impact protector 4 and the second impact protector 5, when the lateral elastic modulus G and the amount of deformation Δt of the thickness due to precompression, the relationship between the thickness ta and the impact reaction force Fa is Fa = GΔt {(1 / ta-1 / Δt) + 1 / (1 / ta-1 / Δt) ² }, and the relationship between the thickness tb and the impact reaction force Fb is Fb = GΔt {(1 / tb-1 / Δt) +1. / (1 / tb-1 / Δt) ² }. Therefore, when the distances a and b shown in FIG. 2 are used, the thicknesses ta and tb are set so as to satisfy the relationship of the following expression (4).
{(1 / ta-1 / Δt) + 1 / (1 / ta-1 / Δt) ² } / {(1 / tb-1 / Δt) + 1 / (1 / tb-1 / Δt) ² } = b / a ・ ・ ・ (4)
When the deformation amount Δt of the thickness due to the precompression is large, it may be simply set so as to satisfy the relationship of the following expression (5).
{(1 / ta-1) + 1 / (1 / ta-1) ² } / {(1 / tb-1) + 1 / (1 / tb-1) ² } = b / a (5)

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. That is, those obtained by appropriately modifying the design of these specific examples by those skilled in the art are also included in the scope of the present invention as long as they have the features of the present invention. The elements and their arrangement, materials, conditions, shapes, sizes, and the like included in each of the specific examples described above are not limited to those illustrated, but can be appropriately changed.

1: Fuel cell stack 2: Cell stack 2A: Short side 2B: Long side 3: Case 4: First impact protector 5: Second impact protector 20: Single cell (cell)
20a: Short side 20b: Long side 20c: Corner portion 30: Communication hole Da: Cell short side width Db: Cell long side width Ea: Elastic modulus of first impact protector Eb: Elastic modulus of second impact protector G: Center of gravity L1: First extension line L1g: First extension line of center of gravity L2: Second extension line L2g: Second extension of center of gravity Ma, Mb: Swing moment S: Cell stacking direction

Claims (1)

A fuel cell comprising a cell stack in which a plurality of rectangular cells are stacked, and a case for housing the cell stack,
A first impact protection body and a second impact protection body disposed between a side surface of the cell stack body along the cell stacking direction and the case;
The first impact protector and the second impact protector are arranged with the corners of the cell sandwiched therebetween when viewed in a cross section perpendicular to the cell stacking direction,
A first extension line passing through the first impact protector and extending in a direction perpendicular to a direction along which the first impact protector of the cell is arranged, and a center of gravity of the cell and extending along the one side. The distance between the first center of gravity extension line extending in the direction perpendicular to the direction is a,
A second extension line that passes through the second impact protector and extends in a direction perpendicular to a direction along the other side of the cell where the second impact protector is disposed, and a second extension line that passes through the center of gravity of the cell and When the distance between the second center of gravity extension line extending in the direction perpendicular to the direction along the side is defined as b,
The fuel cell, wherein the ratio of the elastic modulus Ea of the first impact protector and the elastic modulus Eb of the second impact protector satisfies the relationship of Ea / Eb = b / a.

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