JP5256683B2 - Pressure structure of laminate - Google Patents

Description

  The present invention relates to a laminate structure in which each element forming a power generation element or a power storage element is stacked, or a stack structure formed by stacking unit power generation elements or unit power storage elements. The present invention relates to a pressurizing structure for tightening and fixing to.

  Some primary batteries and fuel cells that are power generation elements, or secondary batteries and capacitors that are power storage elements have a structure in which the elements forming the power generation element or the power storage element are stacked. Alternatively, there is one having a stacked structure in which unit power generation elements or unit storage elements are stacked. It is known that such a laminate can be clamped in the laminating direction and a pressing force can be uniformly applied to obtain stable and good characteristics and a long life. Conventionally, a structure using a disc spring or a coil spring has been disclosed as a structure in which pressure is applied via upper and lower end plates of a laminated structure (see, for example, Patent Documents 1, 2, 3, and 4).

An example of the fuel cell stack will be described with reference to FIG.
As shown in FIG. 16, end plates 72 provided at both ends of the laminated body 71 are pressed against the laminated body 71 by fastening bolts 78 via springs 76 and pressing plates 74 and 75. The fastening bolt 78, the washer 79, and the nut 77 are used to integrate the fastening structure such as the laminate 71, the end plate 72, the pressing plates 74, 75, and the spring 76. These apply a predetermined pressure to the spring 76 and a uniform pressure to the laminated body 71 via the end plate 72. As the spring 76, a coil spring, a disc spring, a leaf spring, or the like is used.
JP 60-225370 A JP 2001-167745 A Japanese Patent Publication No. 3-20030 JP 2006-49221 A

  However, in the conventional structure, the pressing plates 74 and 75 for applying pressure to the laminate 71 and the end plate 72 are necessary. Moreover, the fastening bolt 78, the washer 79, and the nut 77 for integrating these are needed. Thus, since the pressurizing structure by fastening surrounds the laminated body, the entire apparatus becomes large.

  For example, as one index for judging the performance of the battery, there is an energy capacity (energy density: Wh / l) per unit battery of the laminate. However, the index (energy filling rate) of how much energy can be packed in the entire device including the fastening structure as a mobile battery or a vehicle battery is also important. That is, even if the energy density is high, if the energy filling rate becomes 50% due to the shape and structure of the casing of the apparatus, the apparent energy density is reduced to half.

  For this reason, when the pressure structure as described above is used, the energy filling rate of the apparatus is lowered by the occupied volume, and the same result as that of lowering the energy density is brought about. Therefore, it is necessary to apply pressure uniformly in the stacking direction without taking up as much space as possible.

  In the structure shown in FIG. 16, it is difficult to achieve both reduction in size and reduction in load variation due to the spring. The reason for this will be briefly described. FIG. 17 shows the relationship between the load on the spring 76 and the amount of spring deformation. As shown in this drawing, in order to set the allowable error ΔP of the spring load P within a predetermined range, the allowable spring deflection error ΔL changes depending on the magnitude of the spring constant. That is, the larger the spring constant, the smaller the spring deflection error ΔL. Conversely, the smaller the spring constant, the greater the spring deflection error ΔL.

  This indicates that regarding a variation in the dimensions of the laminated body 71, a spring having a smaller spring constant has a larger allowable variation range than a spring having a large spring constant. If the spring load is greater than the appropriate load, the strength of the laminate structure becomes a problem. For this reason, it is not possible to apply a spring load that is larger than the appropriate load to increase the spring deflection error ΔL. However, a spring having a small spring constant has a longer free length for obtaining a necessary spring load (appropriate load) than a spring having a large spring constant. Therefore, a large space is required to wrap the laminated body 71, and the entire apparatus is increased in size.

  Here, a fastening structure in which the dimensions of the laminated body 71 are specifically 15 mm high, 35 mm wide, 80 mm deep, and the applied pressure is 100 N to 110 N and compared is shown below. The dimensions of the disc spring 86 shown in FIG. 18 are a plate thickness of 0.4 mm, an outer diameter of 32 mm, an inner diameter of 16 mm, and a free height of 1.5 mm. The spring constant at this time is 110 N / mm. The dimensions of the coil spring 96 shown in FIG. 19 are a wire diameter of 1.7 mm, a free length of 7.5 mm, a center diameter of 8 mm, and an effective number of turns of 3. The spring constant at this time is 53.4 N / mm.

  As shown in FIG. 17, when the spring load of the disc spring 86 changes from 100N to 110N, the amount of spring deformation changes from 0.91 mm to 1.0 mm. Therefore, the spring load of the disc spring 86 will depart from a predetermined range unless the variation in the dimensions of the laminated body 71 falls within 1.0 mm. On the other hand, when the spring load of the coil spring 96 changes from 100N to 110N, the amount of spring deformation changes from 1.87 mm to 2.06 mm. However, the free length of the coil spring 96 is as long as 7.5 mm.

  Furthermore, each element forming the power generation element or the power storage element constituting the laminate, the unit power generation element, or the unit power storage element has some dimensional variation. Therefore, the variation is further increased by laminating them. Thus, when the dimension of the lamination direction of a laminated body varies for each product, the applied pressure also varies when tightened with a fastening structure, resulting in variations in characteristics and life.

  An object of the present invention is to provide a pressurizing structure for a laminate that simplifies the structure for pressing the laminate in the laminating direction, thereby simultaneously improving the spring property, the space saving property, and the assemblability.

  In order to solve such a problem, the pressurizing structure of the present invention includes a pair of end plates and a plate-like elastic body positioned above and below the laminate. The plate-like elastic body sandwiches the end plate from above and below and pressurizes the laminated body in the laminating direction. By using the pressure structure having such a simple structure, it is possible to improve the space saving property and the assembling property while pressurizing the laminated body with an appropriate pressure in the laminating direction.

  ADVANTAGE OF THE INVENTION According to this invention, while pressing a laminated body, it can provide the pressurization structure characterized by pressing simultaneously in a lamination direction. The present invention provides a laminated body capable of simultaneously improving the spring characteristics, space saving, and assemblability by integrating the pressing plate and all of the pressure parts such as springs or fastening bolts, nuts, and washers. A pressure structure can be provided.

Figure 1 is a perspective view of a fuel cell having a product layer body pressure structure, FIG. 2 is a sectional view of the fuel cell. FIG. 3 is a side view of a leaf spring 10 which is a plate-like elastic body constituting the laminate pressing structure of FIG. FIG. 3 shows a state of the leaf spring 10 before the laminated stack 1 and the end plate 13 which are laminated bodies are inserted. The cross-sectional shape of the leaf spring 10 is a groove shape. That is, the leaf spring 10 has a bottom surface portion 12 and two side surface portions 11 bent from the bottom surface portion 12, and has a U-shape with the stacked stack 1 and the end plate 13 inserted. The leaf spring 10 can be formed by pressing. Further, it can be formed by extrusion or drawing. The end plate 13 can be made of metal or ceramic.

  The multilayer stack 1 includes a plurality of membrane electrode assemblies (hereinafter referred to as MEAs) which are electromotive parts, a plurality of separators arranged so as to sandwich the MEA, and a pair of end plates (all shown). ) The end plate sandwiches the MEA and the separator from both ends in the stacking direction of the MEA, that is, from both ends in the stacking direction of the MEA and the separator. The MEA is configured by laminating an anode electrode, a cathode electrode, and an electrolyte membrane interposed therebetween (none of which is shown). The thickness of the stacked stack 1 is, for example, 19 mm.

  1 and 2 show a state in which the laminated stack 1 and the two end plates 13 are inserted and pressed between the two side surface portions 11 of the leaf spring 10. The side surface portion 11 holds the stacked stack 1. The bottom surface portion 12 is not in direct contact with the laminated stack 1. End plates 13 are positioned above and below the stack 1. Thus, since the laminated stack 1 is pressed by the restoring force of the leaf spring 10, adjustment of the pressing force is unnecessary. Also, assembly is easy. Furthermore, the size can be reduced. And removal is also easy.

  As shown in FIG. 3, the angle formed between the bottom surface portion 12 and the side surface portion 11 of the leaf spring 10 before inserting the stacked stack 1 is approximately 90 degrees after the stacked stack 1 is inserted and pressed. It is preferable to set it to less than 90 degrees. When the pressure is approximately 90 degrees after pressurization, the compression force of the leaf spring 10 is increased, and the volume occupied by the leaf spring 10 is reduced, thereby improving the space saving. Further, from the viewpoint of space saving, the bottom surface portion 12 of the leaf spring 10 may be curved before inserting the laminated stack 1 and the end plate 13, but is preferably planar.

  The leaf spring 10 can be positioned by bringing the bottom surface portion 12 of the leaf spring 10 and the end portion of the end plate 13 into contact with each other. In this case, when the end plate 13 is made of a conductor and also serves as an electrode, it is necessary to provide an insulating layer inside the leaf spring 10 so as not to cause a short circuit.

  As an assembling procedure, the laminated stack 1 and the two end plates 13 are inserted in a state where the side surface portion 11 of the leaf spring 10 is opened in the direction of the arrow by an opening jig (not shown) as shown in FIG. Thereafter, the laminated jig 1 is pressed by the restoring force of the leaf spring 10 by removing the opening jig.

  In addition, as shown in FIG. 5, you may use the leaf | plate spring 10A divided | segmented into plurality in the depth direction. In this configuration, the pressure distribution acting on the stacked stack 1 can be made uniform. Three or more divisions are preferable, but division into more than that is also possible. Optimally, 3 to 4 divisions are good.

  Further, as shown in FIG. 6, two leaf springs 10 may be used. By sandwiching the laminated stack 1 and the two end plates 13A from the left and right sides by the two leaf springs 10, the laminated stack 1 can be pressed in a balanced manner. That is, the two leaf springs 10 sandwich the end plate 13A so that the bottom surface portions 12 thereof face each other. The end plate 13 </ b> A preferably includes a thick portion 23 and a thin portion 24. When such an end plate 13A is used, the leaf spring 10 can be positioned by bringing the leading end portion of the side surface portion 11 of the leaf spring 10 into contact with the thick portion 23. If it does in this way, the leaf | plate spring 10 can be positioned so that the bottom face part 12 may not contact the end plate 13A and the lamination | stacking stack 1. FIG.

  In addition, the preferable angle which the bottom face part 12 and the side part 11 of the leaf | plate spring 10 make, the structure which divides | segments the leaf | plate spring 10 into plurality, or the structure clamped from the right and left both sides with the two leaf | plate springs 10 are demonstrated below. The present invention can also be applied to the embodiment.

FIG. 7 is a cross-sectional view of a fuel cell having a laminate pressure structure. FIG. 8 is a side view of a leaf spring 10B that is a plate-like elastic body constituting the laminated body pressurizing structure shown in FIG. FIG. 8 shows a state of the leaf spring 10B before the stack 1 and the end plate 13A are inserted. In the present embodiment, protrusions 25 for pressing the end plate 13A are provided on the side surface portions 11B of the two leaf springs 10B. The other configuration is the same as that of FIG.

  Thus, by providing the protrusions 25 on the side surface portions 11B of the leaf spring 10B, the point of action of the force applied to the end plate 13A by the leaf spring 10B is uniquely determined, and the applied pressure can be stabilized. By appropriately designing the position La of the protrusion 25, the pressure acting on the end plate 13A can be made uniform.

  FIG. 9A is a 1/4 finite element analysis model diagram of the laminated stack 1, the end plate 13A, and the leaf spring 10B. The stack 1 includes unit cells 101, 102, 103 of three fuel cells. FIG. 9B shows a finite element analysis result, which is a graph showing the compression deformation of the unit cells 101, 102, and 103 with respect to the distance from the center 104 of the stacked stack 1. In the model shown in FIG. 9A, the thickness of each unit cell before pressurization is 0.65 mm. On the other hand, the thickness after pressurization is distributed in the vicinity of 0.5 mm at any unit cell and at any position as shown in FIG. As described above, the amount of compressive deformation of the unit cells 101, 102, 103 is almost constant at any position.

  FIG. 9C shows the compressive stress distribution of three unit cells. It can be seen that the compressive stress is uniform in a certain range from 0.20 MPa to 0.22 MPa in any unit cell.

  In order to obtain a constant compressive stress and a uniform compressive distribution in this way, the distance La from the protrusion 25, which is the contact point with the end plate 13A, to the center of the multilayer stack 1 is set to the width Lo of the multilayer stack 1. It is preferable to set it as 12% or more and 38% or less. From the finite element method analysis result in which the distance La of the protrusion 25 is changed, it is found that the distance La is particularly preferably about ¼ of the width Lo.

  In the finite element analysis of FIG. 9, the angle formed by the side surface portion 11B and the bottom surface portion 12 of the leaf spring 10B is set to about 75 degrees in advance, and the position of the protrusion 25 is the width of the stacked stack 1 from the center of the stacked stack 1. The case where it is about 25% is shown. That is, in FIG. 7, the distance La from the center of the multilayer stack 1 to the protrusion 25 is about ¼ (25%) of the width Lo of the multilayer stack 1 to equalize the pressure distribution acting on the multilayer stack 1. It has been shown that you can.

(Embodiment 1 )
FIG. 10 is a cross-sectional view of a fuel cell having a stacked body pressurizing structure according to Embodiment 1 of the present invention, and FIG. FIG. FIG. 11 shows a state of the leaf spring 10C before the laminated stack 1 and the end plate 13A are inserted. In the present embodiment, the two leaf springs 10C each have a folded portion 26 that is bent at the end of the side surface portion 11C in a direction in which the side surface portions 11C face each other. The other configuration is the same as that of FIG.

  In this way, by providing the folded portion 26 by bending the tip portion of the side surface portion 11C of the leaf spring 10C, the spring constant of the leaf spring 10C can be reduced and the spring property can be improved. Further, by appropriately designing the folded portion 26, the point of action of the force applied to the end plate 13A is uniquely determined, and the applied pressure can be stabilized.

  As shown in FIG. 10, the distance La from the contact point between the folded portion 26 and the end plate 13 </ b> A to the center of the multilayer stack 1 is set to 12% or more and 38% or less of the width Lo of the multilayer stack 1. The pressure distribution acting on can be made uniform. In particular, the distance La is preferably about ¼ of the width Lo.

(Embodiment 2 )
FIG. 12 is a cross-sectional view of a fuel cell having a laminate pressure structure according to Embodiment 2 of the present invention. FIG. 13A is a top view of a leaf spring 10D which is a plate-like elastic body constituting the laminate pressing structure shown in FIG . 12, and FIG. 13B is a plate constituting the laminate pressing structure shown in FIG. It is a side view of leaf spring 10D which is a shape-like elastic body . However, FIG. 13 (a), the shows (b) state before insertion of the laminate stack 1, the end plate 13A is. In the present embodiment, an opening 271 is provided in the side surface portion 11D of the two leaf springs 10D. The leaf spring 10 </ b> D has a bent portion 27 formed by bending the side portion 11 </ b> D in a direction in which the side portions 11 </ b> D are opposed to the portion surrounded by the opening 271. The other configuration is the same as that of FIG.

  The opening portion 271 is provided by cutting the side surface portion 11D, and the spring portion of the leaf spring 10D is improved by forming the bent portion 27 by bending the inner portion surrounded by the opening portion 271 with a bending line 272. I am letting.

  Further, by appropriately designing the length and roundness of the bending portion 27, the acting force and the acting point of the force applied to the end plate 13A are uniquely determined, and the applied pressure can be stabilized. As shown in FIG. 12, the distance La from the contact point between the bent portion 27 and the end plate 13 </ b> A to the center of the multilayer stack 1 is set to 12% or more and 38% or less of the width Lo of the multilayer stack 1. The pressure distribution acting on can be made uniform. In particular, the distance La is preferably about ¼ of the width Lo.

(Embodiment 3 )
FIG. 14 is a cross-sectional view of a fuel cell having a laminate pressurizing structure according to Embodiment 3 of the present invention. FIG. 15 is a cross-sectional view of the end plate 13B constituting the laminated body pressing structure shown in FIG. In the present embodiment, the projection 31 is provided on the thin portion 24 of the end plate 13B, and the leaf spring 10 hits the projection 31 to sandwich the end plate 13B. The other configuration is the same as that of FIG.

  Thus, by providing the protrusion 31 on the end plate 13B, the point of action of the force applied to the end plate 13B is uniquely determined, and the applied pressure can be stabilized. In particular, as shown in FIG. 15, the distance La from the protrusion 31 that is the contact point between the end plate 13 </ b> B and the leaf spring 10 to the center of the laminated stack 1 is 12% to 38% of the width Lo of the laminated stack 1. Thus, the pressure distribution acting on the laminated stack 1 can be made uniform. In particular, the distance La is preferably about ¼ of the width Lo.

  A plurality of protrusions 31 may be provided before and after the distance La. By providing a plurality, the pressure distribution can be made more uniform.

  In the pressurizing structure of the laminate according to the present invention, the laminate can be sandwiched and pressed in the stacking direction. Further, all of the pressurizing parts can be integrated with the plate-like elastic body, and the spring characteristics, space saving, and assembly can be improved at the same time. Such a pressurizing structure of the laminated body is useful for a laminated body formed by laminating elements forming a primary battery or a fuel cell as a power generation element, or a secondary battery or a capacitor as a power storage element. Furthermore, it is also useful for a stacked stack in which unit power generation elements or unit storage elements are stacked.

Perspective view of a fuel cell having a product layer body pressure structure Cross section of the fuel cell Side view of a plate-like elastic body constituting the laminate pressing structure Assembly diagram of the fuel cell The perspective view of the fuel cell which has another laminated body pressurization structure Sectional view of a fuel cell having another laminated body pressurization structure Cross-sectional view of a fuel cell with a product layer body pressure structure Side view of a plate-like elastic body constituting the laminate pressing structure (A) 1/4 finite element analysis model diagram of the fuel cell, (b) finite element analysis result graph, (c) finite element analysis result graph Sectional drawing of the fuel cell which has the laminated body pressurization structure by Embodiment 1 of this invention Side view of a plate-like elastic body constituting the laminate pressing structure Sectional drawing of the fuel cell which has the laminated body pressurization structure by Embodiment 2 of this invention (A) Top view of a plate-like elastic body constituting the laminate pressure structure , (b) Side view Sectional drawing of the fuel cell which has the laminated body pressurization structure by Embodiment 3 of this invention Sectional drawing of the end plate which comprises the laminated body pressurization structure Cross section of conventional fuel cell Graph showing the relationship between the load on the spring and the amount of spring deformation in a conventional fuel cell Sectional view of a disc spring used in a conventional fuel cell Sectional view of a coil spring used in a conventional fuel cell

Explanation of symbols

1 Laminate stack (laminate)
10, 10A, 10B, 10C, 10D Leaf spring 11, 11B, 11C, 11D Side face part 12 Bottom face part 13, 13A, 13B End plate 23 Thick part 24 Thin part 25 Protrusion part 26 Turned part 27 Bending part 31 Protrusion 71 Laminated body 72 End plate 74, 75 Press plate 76 Spring 77 Nut 78 Fastening bolt 79 Washer 86 Belleville spring 96 Coil spring 101, 102, 103 Unit cell 104 Center 271 Opening 272 Bending line

Claims (5)

A laminated body formed by laminating elements for forming a power generation element or a power storage element, or a pressurizing structure of a laminated body that is a laminated stack formed by laminating a unit power generation element or a unit power storage element,
A pair of end plates positioned above and below the laminate;
A plate-like elastic body that clamps the end plate from above and below and pressurizes the laminated body in the laminating direction;
A cross-sectional shape of the plate-like elastic body is a groove type having a bottom surface portion and two side surface portions bent from the bottom surface portion, and the plate-like elastic body is formed between the side surface portions at the end of the side surface portion. Has a folded portion folded in the opposite direction,
A pressurizing structure for a laminate, wherein the end plate is provided with a thick portion, and a tip portion of the folded portion of the plate-like elastic body is brought into contact with the thick portion. A laminated body formed by laminating elements for forming a power generation element or a power storage element, or a pressurizing structure of a laminated body that is a laminated stack formed by laminating a unit power generation element or a unit power storage element,
A pair of end plates positioned above and below the laminate;
A plate-like elastic body that clamps the end plate from above and below and pressurizes the laminated body in the laminating direction;
A cross-sectional shape of the plate-like elastic body is a groove type having a bottom surface portion and two side surface portions bent from the bottom surface portion, and an opening is provided in the side surface portion of the plate-like elastic body. The plate-like elastic body has a bent portion formed by bending a portion surrounded by the opening portion in a direction in which the side surface portions face each other.
A pressurizing structure for a laminate, wherein a thick portion is provided on the end plate, and a tip portion of the side surface portion of the plate-like elastic body is brought into contact with the thick portion. A laminated body formed by laminating elements for forming a power generation element or a power storage element, or a pressurizing structure of a laminated body that is a laminated stack formed by laminating a unit power generation element or a unit power storage element,
A pair of end plates positioned above and below the laminate;
A plate-like elastic body that clamps the end plate from above and below and pressurizes the laminated body in the laminating direction;
The cross-sectional shape of the plate-like elastic body is a groove type having a bottom surface portion and two side surface portions bent from the bottom surface portion,
A projection is provided on the end plate, and the plate-like elastic body sandwiches the end plate at the projection,
A pressurizing structure for a laminate, wherein a thick portion is provided on the end plate, and a tip portion of the side surface portion of the plate-like elastic body is brought into contact with the thick portion. The state of the plate-like elastic body in a state before the laminate body is pressurized so that an angle formed between the bottom surface portion and the side surface portion of the plate-like elastic body becomes a right angle in a state where the laminate body is pressurized. The pressurizing structure for a laminate according to any one of claims 1 to 3, wherein an angle formed by a bottom surface portion and the side surface portion is set in advance to be less than 90 degrees. The angle formed by the bottom surface portion and the side surface portion of the plate-like elastic body in a state before pressurizing the laminated body is set to 65 degrees or more and 85 degrees or less. Pressurized structure of the laminate.

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