Pressurization mechanism, battery pack, and press device

Abstract

This pressurization mechanism comprises: a reaction force generation body that is provided between a first member and a second member, which face each other in a first direction and for which the distance therebetween changes, and that elastically deforms following displacement of the first member or the second member; a first rigid body plate that is positioned closer to the second member than the reaction force generation body; and a first pressure equalization layer that is sandwiched between the first rigid body plate and the second member in the first direction. The reaction force generation body is partially in contact with a surface of the first rigid body plate that faces the first-member side. The first pressure equalization layer disperses and transmits, to the second member in a direction intersecting the first direction, a load that is partially applied to the first rigid body plate from the reaction force generation body.

Description

Pressure mechanism, battery pack, press device

[0001] The present invention relates to a pressurizing mechanism, a battery pack, and a press device. This application claims priority based on Japanese Patent Application No. 2024-114075, filed on July 17, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, a configuration in which a pressure mechanism is provided between two opposing components, for example, in a battery pack, a press device, etc., to press one of the components in a first direction. One such pressure mechanism, as shown in Patent Document 1 below, includes a compression spring that contacts the surface of an end plate facing the secondary battery and elastically deforms in response to displacement of the end plate, a core material that sandwiches the compression spring between the surface of the end plate in the first direction, and an elastic member that is sandwiched in the first direction between the core material and the secondary battery. In this pressure mechanism, the compression spring and the elastic member elastically deform as the secondary battery expands in the first direction, thereby maintaining performance and preventing damage, for example.

[0003] Japan Republished Publication No. 2019 / 003772

[0004] In conventional pressure mechanisms, it was difficult to make the surface pressure applied by the elastic member to the secondary battery, which is a member that is subjected to a load, uniform within the surfaces where the two members abut against each other, for example, the surface pressure applied to the secondary battery from the center of the elastic member was higher than the surface pressure applied from the outer periphery of the elastic member.

[0005] The present invention provides a pressure mechanism, a battery pack, and a press device that can make the surface pressure applied to members to which a load is applied uniform within the surfaces where the members abut against each other.

[0006] A pressure mechanism according to one aspect of the present invention is a pressure mechanism provided between a first member and a second member that face each other in a first direction and the distance between the members changes, and includes a reaction force generating body that elastically deforms in response to displacement of the first member or the second member, a first rigid plate that is positioned closer to the second member than the reaction force generating body, and a first pressure equalizing layer that is sandwiched between the first rigid plate and the second member in the first direction, wherein the reaction force generating body partially abuts against the surface of the first rigid plate that faces the first member, and the first pressure equalizing layer distributes and transmits the load that is partially applied to the first rigid plate from the reaction force generating body to the second member in a direction intersecting the first direction.

[0007] The pressure mechanism applies a load to the second member in the first direction via the first pressure-equalizing layer using a reaction force generated by the reaction force generating body. Therefore, even if the reaction force generating body partially abuts against the surface of the first rigid plate, the load partially applied from the reaction force generating body to the first rigid plate can be dispersed in a direction intersecting the first direction by the first pressure-equalizing layer and transmitted to the second member. As a result, the surface pressure applied to the second member by the first pressure-equalizing layer can be made uniform within the abutting surface. Forming the first pressure-equalizing layer from a material other than a rubber material or an elastomer can reduce hysteresis loss and the temperature dependence of the load-deflection characteristics.

[0008] A large number of voids may be provided over the entire area of ​​the first pressure equalizing layer in a direction intersecting the first direction, at least on the surface thereof that is pressed against the second member.

[0009] The first pressure equalizing layer has a large number of voids formed across the entire area in a direction intersecting the first direction, at least on the surface side that is pressed against the second member. This makes the first pressure equalizing layer more easily deformable as the voids are crushed. Therefore, when a load from the reaction force generator is applied to the first pressure equalizing layer, at least the pressing surface side of the first pressure equalizing layer can be easily deformed with little bias across the entire area, regardless of the constraint conditions. Furthermore, by distributing the load from the first rigid plate across the first pressure equalizing layer, the first pressure equalizing layer can be pressed against the second member evenly with little bias across the entire area within the surface that abuts against the second member.

[0010] The large number of voids may be provided across the entire area of ​​the first pressure equalizing layer in the first direction.

[0011] A large number of voids are provided throughout the first pressure equalizing layer in the first direction and in a direction intersecting the first direction, so that when a load is applied to the first pressure equalizing layer from the reaction force generator, the first pressure equalizing layer can be easily deformed evenly throughout the entire area, regardless of the constraint conditions.

[0012] The first pressure-equalizing layer may contain metal fibers, glass fibers, pulp, resin fibers, or carbon fibers.

[0013] The first pressure-equalizing layer contains metal fiber, glass fiber, pulp, resin fiber, or carbon fiber. In this case, the elastic modulus of the first pressure-equalizing layer can be increased and voids can be easily formed in the first pressure-equalizing layer. Therefore, the surface pressure applied from the first pressure-equalizing layer to the second member can be reliably made uniform within the contact surface.

[0014] The first pressure-equalizing layer may be made of glass nonwoven fabric, glass wool, or metal fiber nonwoven fabric, in which the fibers are randomly bonded by at least one of entanglement, adhesion, fusion, and sintering, or a knitted mesh spring.

[0015] The first pressure-equalizing layer is made of glass nonwoven fabric, glass wool, metal fiber nonwoven fabric, or mesh spring. In this case, the fibers are more likely to move when a load from the reaction force generator is applied to the first pressure-equalizing layer. This makes it possible to reliably crush any voids present in the first pressure-equalizing layer, and to reliably press the first pressure-equalizing layer against the second member evenly and with little bias across the entire surface of the first pressure-equalizing layer that abuts against the second member.

[0016] The first pressure equalizing layer may be made of a wet-laid nonwoven fabric.

[0017] The first pressure-equalizing layer is made of a wet-laid nonwoven fabric. In this case, short fibers can be used as the fibers used in the first pressure-equalizing layer. This increases the number of contact points between the first pressure-equalizing layer and the second member when a load from the reaction force generator is applied to the first pressure-equalizing layer. Furthermore, by making the first pressure-equalizing layer of a wet-laid nonwoven fabric, the fiber density of the first pressure-equalizing layer can be made uniform throughout the entire area. Furthermore, the thickness of the first pressure-equalizing layer can be precisely controlled, making the thickness of the first pressure-equalizing layer uniform throughout the entire area. This allows the first pressure-equalizing layer to distribute the load applied from the reaction force generator in a direction intersecting the first direction and transmit the load evenly to the second member.

[0018] The first pressure-equalizing layer is a wet-laid nonwoven fabric whose main material is glass fiber, and the basis weight of the first pressure-equalizing layer is 50 g / m ２ It may be more than that.

[0019] The first equalizing layer is a wet-laid nonwoven fabric whose main material is glass fiber, and the basis weight of the first equalizing layer is 50 g / m ２ In this case, when a load from the reaction force generator is applied to the first pressure equalizing layer, the glass fibers in the first pressure equalizing layer move and deform, increasing the area of ​​contact with the second member, allowing the first pressure equalizing layer to contact the second member evenly across the entire surface of the first pressure equalizing layer that contacts the second member. As a result, the first pressure equalizing layer can be pressed against the second member reliably and evenly with little bias within the surface of the first pressure equalizing layer that contacts the second member.

[0020] The first pressure equalizing layer may be made of a cork sheet or a sponge sheet.

[0021] The first pressure-equalizing layer is made of a cork sheet or a sponge sheet. In this case, the first pressure-equalizing layer has voids therein and is elastic or flexible. Therefore, when a load is applied to the first pressure-equalizing layer from the reaction force generator, the voids in the first pressure-equalizing layer can be reliably crushed, and the first pressure-equalizing layer can be reliably pressed against the second member evenly and with little bias across the entire surface that abuts against the second member.

[0022] The first rigid plate may have minute irregularities formed thereon, and the thickness of the first pressure equalizing layer may be greater than the maximum value of the height difference in the minute irregularities in the first direction.

[0023] The thickness of the first pressure-equalizing layer is greater than the maximum height difference in the first direction of the fine irregularities of the first rigid plate. Therefore, by squashing the voids, the first pressure-equalizing layer can conform to the surface shape of the fine irregularities of the first rigid plate, preventing the convex portions of the fine irregularities from locally hitting the second member through the first pressure-equalizing layer. As a result, the surface pressure applied from the first pressure-equalizing layer to the second member can be reliably made uniform within the contacting surfaces.

[0024] The reaction force generator may be a disc spring.

[0025] The reaction force generating body is a disc spring. Therefore, when the reaction force generating body is used in a region of its load-deflection characteristic curve that includes both a positive slope and a negative slope, or a region that includes a small positive or negative slope, fluctuations in the repulsive force generated by the reaction force generating body are kept small even if the reaction force generating body is significantly deformed in the first direction. Therefore, even if the first member and the second member are significantly displaced relative to each other in the first direction, the surface pressure applied to the second member by the first pressure equalizing layer can be made less variable within the contact surface.

[0026] The reaction force generator may come into contact with a surface of the first member facing the second member.

[0027] The pressure mechanism may further include a second rigid plate located closer to the first member than the reaction force generating body, and a second pressure-equalizing layer sandwiched between the second rigid plate and the first member in the first direction, wherein the reaction force generating body partially abuts against a surface of the second rigid plate facing the second member, and the second pressure-equalizing layer may distribute and transmit the load partially applied from the reaction force generating body to the second rigid plate in a direction intersecting the first direction to the first member.

[0028] The pressurizing mechanism applies a load to the first member in the first direction via the second pressure-equalizing layer using a reaction force generated by the reaction force generator. Therefore, even if the reaction force generator partially abuts the second rigid plate, the load partially applied to the second rigid plate via the reaction force generator can be dispersed in a direction intersecting the first direction by the second pressure-equalizing layer and transmitted to the first member. As a result, the surface pressure applied to the first member from the second pressure-equalizing layer can be made uniform within the abutting surface.

[0029] A battery pack according to one aspect of the present invention comprises a pair of end plates spaced apart in the first direction, a plurality of battery cells stacked in the first direction, and at least one pressure mechanism, the pressure mechanism being the pressure mechanism of the present invention, and the pressure mechanism and the plurality of battery cells being arranged between the pair of end plates.

[0030] According to the battery pack having the above configuration, it is possible to maintain the battery performance and prevent damage.

[0031] At least one pressure mechanism may be provided between the pair of end plates and the plurality of battery cells, the first member for one of the at least one pressure mechanism may be one of the pair of end plates, the second member may be the plurality of battery cells, and the reaction force generator may be in contact with the surface of one of the end plates facing the second member.

[0032] The pressure mechanism of the present invention applies a load to the plurality of battery cells in a first direction via the first pressure equalizing layer. Therefore, the surface pressure applied to the battery cells from the first pressure equalizing layer can be made uniform within the mutual contact surfaces, thereby maintaining battery performance and preventing damage. The pressure mechanism applies a load to the plurality of battery cells via the first pressure equalizing layer. As a result, even if some of the plurality of battery cells tend to tilt relative to the other battery cells, the reaction force generator and the first pressure equalizing layer deform, thereby suppressing this tilt.

[0033] The at least one pressure mechanism is provided between at least one of the plurality of battery cells adjacent to each other in the first direction, and the adjacent battery cells in the first direction are the first member and the second member for one of the at least one pressure mechanism, and the pressure mechanism further includes a second rigid plate located closer to the first member than the reaction force generator, and a second pressure equalizing layer sandwiched in the first direction between the second rigid plate and the first member, and the reaction force generator partially abuts against a surface of the second rigid plate facing the second member, and the second pressure equalizing layer may distribute and transmit the load partially applied from the reaction force generator to the second rigid plate to the first member in a direction intersecting the first direction.

[0034] The pressure mechanism of the present invention, which further includes a second rigid plate and a second pressure-equalizing layer, is provided between adjacent battery cells in the first direction, and these battery cells are designated as the first member and the second member. Therefore, the surface pressure applied by the reaction force generator to each of the two battery cells sandwiching the pressure mechanism in the first direction can be made uniform within the mutual contact surfaces, thereby maintaining battery performance and preventing damage.

[0035] A third pressure equalizing layer may be provided between adjacent battery cells in the first direction among the plurality of battery cells.

[0036] A third pressure equalizing layer is provided between adjacent battery cells in the first direction. Therefore, the surface pressure applied to the load-bearing members between the battery cells can be made uniform within the mutual contact surfaces. This improves battery efficiency. Furthermore, the performance of the battery pack is improved, and the life of the battery pack can be extended.

[0037] A fourth pressure equalizing layer may be provided between the pair of end plates and at least one of the plurality of battery cells that is adjacent to the other end plate of the pair of end plates in the first direction.

[0038] A fourth pressure equalizing layer is provided between the end plate and at least one of the plurality of battery cells that is adjacent to the other end plate in the first direction, thereby further improving the performance of the battery pack and extending the life of the battery pack.

[0039] A press device according to one aspect of the present invention comprises a pressure plate, a pressed body, and a pressure mechanism of the present invention, wherein the pressure mechanism is provided between the pressure plate and the pressed body, the first member is the pressure plate, and the second member is the pressed body.

[0040] The pressure mechanism of the present invention applies a load to a pressed body via a first pressure-equalizing layer in a press device. Therefore, the surface pressure applied to the pressed body from the first pressure-equalizing layer can be made uniform within the contacting surfaces. For example, in a press device in which the pressed body is a pair of bonded members sandwiching an adhesive foil in a first direction and the pair of bonded members is pressed by a pressure plate via the first pressure-equalizing layer, the abutting surfaces of each of the pair of bonded members sandwiching the adhesive foil in the first direction can be uniformly bonded across the entire area.

[0041] According to the above aspects of the present invention, in the pressurizing mechanism, the battery pack, and the press device, the surface pressure applied to the members to which the load is applied can be made uniform within the surfaces where the members abut against each other.

[0042] FIG. 1 is a longitudinal cross-sectional view along the first direction of a pressure mechanism of one embodiment; FIG. 2 is a longitudinal cross-sectional view along the first direction of a battery pack of the first embodiment; FIG. 3 is a longitudinal cross-sectional view along the first direction of a battery pack of the second embodiment; FIG. 4 is a longitudinal cross-sectional view along the first direction of a battery pack of the third embodiment; FIG. 5 is a longitudinal cross-sectional view along the first direction of a battery pack of the fourth embodiment; FIG. 6 is a side view of a press device of one embodiment, viewed from a direction perpendicular to the first direction; FIG. 7 is a diagram showing an enlarged photograph of a first pressure equalizing layer used in a first verification test; FIG. 8 is a diagram showing a surface pressure distribution obtained in the first verification test; FIG. 9 is a graph showing the correlation between the basis weight of the first pressure equalizing layer and the coefficient of variation of surface pressure in a second verification test; and FIG. 10 is a diagram showing a surface pressure distribution obtained in a third verification test.

[0043] An embodiment of the pressure mechanism will be described below with reference to Fig. 1. The pressure mechanism 1 of this embodiment includes a reaction force generator 13, a first rigid plate 11, and a first pressure equalizing layer 14.

[0044] The pressure mechanism 1 is provided between a first member 12 and a second member 10 that face each other in the first direction Z. The first member 12 and the second member 10 are displaced relative to each other so that the distance between them changes in the first direction Z. Either the first member 12 or the second member 10 may be movable, or both the first member 12 and the second member 10 may be movable. The reaction force generator 13 of the pressure mechanism 1 deforms due to the displacement of the first member 12 or the second member 10, generating a load.

[0045] In the illustrated example, the first member 12 is formed in a plate shape with its front and back surfaces facing the first direction Z. The first member 12 is not limited to a plate shape and may be formed in a block shape, for example. The front and back surfaces of the first member 12 face the first direction Z. The front and back surfaces of the first rigid plate 11 face the first direction Z. The back surface 12a of the first member 12 facing the second member 10 and the front surface 11a of the first rigid plate 11 face each other in the first direction Z. The first rigid plate 11 is located closer to the second member 10 than the reaction force generator 13. The back surface 12a of the first member 12 and the front surface 11a of the first rigid plate 11 sandwich the reaction force generator 13 in the first direction Z. The first member 12 and the first rigid plate 11 are formed from a material, such as a metal, that undergoes minimal deformation due to loads from the reaction force generator 13 and the second member 10.

[0046] The reaction force generating body 13 abuts against the back surface 12a of the first member 12 and elastically deforms in response to displacement of the first member 12 or the second member 10. The reaction force generating body 13 generates a reaction force in a direction that moves the first member 12 and the first rigid plate 11 away from each other in the first direction Z. In the example shown in the figure, the reaction force generating body 13 is a disc spring. Hereinafter, the direction that passes through the center of the reaction force generating body 13 and intersects with the center line O extending in the first direction Z when viewed from the first direction Z is referred to as the radial direction.

[0047] The reaction force generator 13 is located radially inward of the outer circumferential edge of the first member 12. The reaction force generator 13 is located radially inward of the outer circumferential edge of the first rigid plate 11. The inner circumferential surface 13a and the outer circumferential surface 13b of the reaction force generator 13 extend toward the first member 12 from the radially outer side to the radially inner side. Note that, for example, a coil spring, a leaf spring, or the like may be used as the reaction force generator 13. Furthermore, a portion of the reaction force generator 13 may be located outside the first member 12 and the first rigid plate 11. For example, a portion of the reaction force generator 13 as a disc spring may protrude from the rectangular first rigid plate 11.

[0048] The reaction force generator 13 is in partial contact with the surface 11a of the first rigid plate 11 facing the first member 12. The reaction force generator 13 is in contact with the surface 11a of the first rigid plate 11, for example, linearly or intermittently. In the example shown in the figure, only the radially outer end of the inner circumferential surface 13a of the reaction force generator 13 is in contact with the surface 11a of the first rigid plate 11 continuously over the entire circumference.

[0049] The first pressure-equalizing layer 14 is sandwiched in the first direction Z between the first rigid plate 11 and the second member 10. The first pressure-equalizing layer 14 distributes and transmits the load, which is partially applied to the surface 11a of the first rigid plate 11 from the reaction force generator 13, to the second member 10 in a direction intersecting the first direction Z. This makes it possible to make the surface pressure uniform within the plane where the first pressure-equalizing layer 14 and the second member 10 abut against each other.

[0050] Here, the back surface 11b of the first rigid plate 11, against which the front surface 14b of the first pressure-equalizing layer 14 is pressed, is formed with fine irregularities such as distortions. The thickness of the first pressure-equalizing layer 14 is greater than the maximum height difference in the first direction Z of the fine irregularities formed on the back surface 11b. Note that the back surface 11b of the first rigid plate 11 does not necessarily have to be formed with fine irregularities. The amount of deformation of the first rigid plate 11 protruding in the first direction Z due to the partial load from the reaction force generator 13 is smaller than the maximum height difference in the first direction Z of the fine irregularities formed on the back surface 11b.

[0051] The first pressure-equalizing layer 14 has a large number of voids formed across the entire area in the direction intersecting the first direction Z, at least on the back surface 14a side that is pressed against the second member 10. As a result, the large number of voids formed on the back surface 14a side of the first pressure-equalizing layer 14 are crushed, making the first pressure-equalizing layer 14 more likely to deform. Therefore, when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13, at least the back surface 14a side of the first pressure-equalizing layer 14 can be easily deformed with little bias across the entire area, regardless of the constraint conditions. Furthermore, by distributing the load from the first rigid plate 11 across the back surface 14a side of the first pressure-equalizing layer 14, the first pressure-equalizing layer 14 can be pressed against the second member 10 evenly with little bias across the entire area within the plane that abuts against the second member 10.

[0052] Preferably, the first pressure equalizing layer 14 has a large number of voids on both sides, i.e., the front surface 14b facing the first direction Z and the back surface 14a, throughout the entire area in a direction intersecting the first direction Z. More preferably, the first pressure equalizing layer 14 has a large number of voids throughout the entire area in the first direction Z and in a direction intersecting the first direction Z. The first pressure equalizing layer 14 has a large number of voids on the front surface 14b side that is pressed against the first rigid plate 11, and by crushing the voids, the first pressure equalizing layer 14 can be easily deformed to follow the shape of the back surface 11b of the first rigid plate 11. This distributes the load from the first rigid plate 11 across the first pressure equalizing layer 14, allowing the first pressure equalizing layer 14 to be pressed against the second member 10 evenly and with little bias throughout the entire area within the plane that abuts against the second member 10.

[0053] Furthermore, the voids may or may not be open so as to penetrate through the first pressure equalizing layer 14 to the front and back surfaces 14a and 14b facing the first direction Z.

[0054] The first pressure-equalizing layer 14 is formed of a material with lower hysteresis loss and temperature dependence of load-deflection characteristics than rubber materials and elastomers. Examples of the first pressure-equalizing layer 14 include fiber-containing plates, spongy plates such as cork sheets and sponge sheets, plates made of mechanical metamaterials, and structures in which powder is contained in a dish. Examples of fiber-containing plates include nonwoven fabrics, woven fabrics, and knitted fabrics in which fibers are randomly bonded by at least one of entanglement, adhesion, fusion, and sintering. Examples of fibers include metal fibers, pulp, glass fibers, resin fibers such as aramid fibers, and carbon fibers. Examples of nonwoven fabrics include glass nonwoven fabrics, glass wool, and metal fiber nonwoven fabrics. Examples of knitted fabrics include melius-knit mesh springs. When the first pressure-equalizing layer 14 is configured such that powder is contained in a dish, the first rigid plate 11 is inserted inside the dish and placed on the powder.

[0055] Preferably, the first pressure equalizing layer 14 is made of a wet-laid nonwoven fabric. A wet-laid nonwoven fabric is a nonwoven fabric manufactured using, for example, a papermaking method. A wet-laid nonwoven fabric can use shorter fibers than a dry-laid nonwoven fabric. Furthermore, a wet-laid nonwoven fabric can have a more uniform fiber density throughout its entire area than a dry-laid nonwoven fabric (i.e., the fiber density distribution is less likely to be uneven). Furthermore, a wet-laid nonwoven fabric can more easily control the thickness of the wet-laid nonwoven fabric than a dry-laid nonwoven fabric, and the thickness of the wet-laid nonwoven fabric can be made more uniform throughout its entire area. That is, by making the first pressure equalizing layer 14 of a wet-laid nonwoven fabric, shorter fibers can be used for the first pressure equalizing layer 14. This increases the number of contact points between the first pressure equalizing layer 14 and the second member 10 when a load from the reaction force generator 13 is applied to the first pressure equalizing layer 14. Furthermore, the first pressure equalizing layer 14 can be more easily deformed to collapse voids. As a result, when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13, the first pressure-equalizing layer 14 can be brought into contact with the second member 10 evenly across the entire surface of the first pressure-equalizing layer 14 that abuts against the second member 10, and the load applied from the reaction force generator 13 can be effectively dispersed by the first pressure-equalizing layer 14 in a direction intersecting the first direction Z. Furthermore, by forming the first pressure-equalizing layer 14 from a wet-laid nonwoven fabric, the fiber density of the first pressure-equalizing layer 14 can be made uniform across the entire surface. Furthermore, by forming the first pressure-equalizing layer 14 from a wet-laid nonwoven fabric, the thickness of the first pressure-equalizing layer 14 can be made uniform across the entire surface. This allows the load applied from the reaction force generator 13 to be dispersed by the first pressure-equalizing layer 14 in a direction intersecting the first direction Z, and transmitted evenly to the second member 10.

[0056] When the first pressure-equalizing layer 14 is a wet-laid nonwoven fabric whose main material is glass fiber, the basis weight of the first pressure-equalizing layer 14 is 50 g / m ２ It is preferable that the weight is 60 g / m or more. ２ More preferably, it is 70 g / m or more. ２ More preferably, it is 80 g / m or more. ２ This makes it possible to suppress unevenness in the surface pressure applied from the first pressure equalizing layer 14 to the second member 10 .

[0057] The first pressure-equalizing layer 14 may be composed of multiple layers. In this case, at least the back surface 14a side of the first pressure-equalizing layer 14 is composed of a layer having numerous voids. When the first pressure-equalizing layer 14 is composed of two layers, the back surface 14a side may be composed of a layer having voids, and the front surface 14b side may be composed of a solid layer. When the first pressure-equalizing layer 14 is composed of three layers, the front surface 14b side and the back surface 14a side may be composed of layers having voids, and the intermediate layer between the layer on the front surface 14b side and the layer on the back surface 14a side may be composed of a solid layer.

[0058] As described above, according to the pressurizing mechanism 1 of this embodiment, a load is applied to the second member 10 in the first direction Z by the reaction force generated by the reaction force generator 13 via the first pressure-equalizing layer 14. Therefore, even if the reaction force generator 13 is in partial contact with the surface 11 a of the first rigid plate 11, the load applied partially from the reaction force generator 13 to the surface 11 a of the first rigid plate 11 can be dispersed by the first pressure-equalizing layer 14 in a direction intersecting the first direction Z and transmitted to the second member 10. As a result, the surface pressure applied from the first pressure-equalizing layer 14 to the second member 10 can be made uniform within the contact surface. If the first pressure-equalizing layer 14 is made of a material other than a rubber material or an elastomer, hysteresis loss and the temperature dependence of the load-deflection characteristics can be suppressed.

[0059] The first pressure-equalizing layer 14 has a large number of voids formed across the entire area in a direction intersecting the first direction Z, at least on the back surface 14a side that is pressed against the second member 10. This makes the first pressure-equalizing layer 14 more easily deformable as the voids are crushed. Therefore, when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13, at least the back surface 14a side of the first pressure-equalizing layer 14 can be easily deformed with little bias across the entire area, regardless of the constraint conditions. Furthermore, by dispersing the load from the first rigid plate 11 across the back surface 14a side of the first pressure-equalizing layer 14, the first pressure-equalizing layer 14 can be pressed against the second member 10 evenly with little bias across the entire area within the plane that abuts against the second member 10.

[0060] A large number of voids are provided throughout the first pressure-equalizing layer 14 in the first direction Z and in a direction intersecting the first direction Z. Therefore, when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13, the first pressure-equalizing layer 14 can be easily deformed evenly throughout the entire area, regardless of the constraint conditions.

[0061] The first pressure-equalizing layer 14 may contain metal fibers, glass fibers, pulp, resin fibers, or carbon fibers. In this case, the elastic modulus of the first pressure-equalizing layer 14 can be increased, and voids can be easily formed in the first pressure-equalizing layer 14. Therefore, the surface pressure applied from the first pressure-equalizing layer 14 to the second member 10 can be reliably made uniform within the contacting surfaces.

[0062] The first pressure-equalizing layer 14 may be made of glass nonwoven fabric, glass wool, metal fiber nonwoven fabric, or mesh spring. In this case, the fibers are more likely to move when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13. This makes it possible to reliably crush any voids present in the first pressure-equalizing layer 14, and to reliably press the first pressure-equalizing layer 14 against the second member 10 evenly and with little bias across the entire area within the surface that abuts against the second member 10.

[0063] The first pressure-equalizing layer 14 may be made of a wet-laid nonwoven fabric. In this case, short fibers can be used as the fibers used in the first pressure-equalizing layer 14 (wet-laid nonwoven fabric). This increases the number of contact points between the first pressure-equalizing layer 14 and the second member 10 when a load from the reaction force generator 13 is applied to the first pressure-equalizing layer 14. Furthermore, by making the first pressure-equalizing layer 14 of a wet-laid nonwoven fabric, the fiber density of the first pressure-equalizing layer 14 can be made uniform throughout the entire area. Furthermore, the thickness of the first pressure-equalizing layer 14 can be precisely controlled, making the thickness of the first pressure-equalizing layer 14 uniform throughout the entire area. This allows the first pressure-equalizing layer 14 to distribute the load applied from the reaction force generator 13 in a direction intersecting the first direction Z and transmit it evenly to the second member 10.

[0064] The first pressure-equalizing layer 14 is a wet-laid nonwoven fabric whose main material is glass fiber, and the basis weight of the first pressure-equalizing layer 14 is 50 g / m２ In this case, when a load from the reaction force generator 13 is applied to the first pressure equalizing layer 14, the glass fibers in the first pressure equalizing layer 14 move and deform, increasing the area of ​​contact with the second member 10, so that the first pressure equalizing layer 14 can be brought into uniform contact with the second member 10 over the entire surface thereof in contact with the second member 10. As a result, the first pressure equalizing layer 14 can be pressed against the second member 10 reliably and evenly with little bias within the surface thereof in contact with the second member 10.

[0065] The first pressure-equalizing layer 14 may be made of a cork sheet or a sponge sheet. In this case, the first pressure-equalizing layer 14 has voids therein and is elastic or flexible. Therefore, when a load is applied to the first pressure-equalizing layer 14 from the reaction force generator 13, the voids in the first pressure-equalizing layer 14 can be reliably crushed, and the first pressure-equalizing layer 14 can be reliably pressed against the second member 10 evenly and with little bias across the entire surface of the first pressure-equalizing layer 14 that abuts against the second member 10.

[0066] The thickness of the first pressure-equalizing layer 14 is greater than the maximum value of the height difference in the first direction Z of the fine irregularities on the back surface 11b of the first rigid plate 11. This makes it possible to prevent convex portions of the fine irregularities from locally hitting the front surface 10a of the second member 10 via the first pressure-equalizing layer 14. Furthermore, by squashing the voids in the first pressure-equalizing layer 14, the first pressure-equalizing layer 14 can conform to the surface shape of the fine irregularities on the first rigid plate 11. This ensures that the surface pressure applied from the first pressure-equalizing layer 14 to the second member 10 is uniform within the contacting surfaces.

[0067] The reaction force generating body 13 is a disc spring. In this case, if the reaction force generating body 13 is used in a region of its load-deflection characteristic curve that includes both a positive slope and a negative slope, or a region that includes a small positive or negative slope, fluctuations in the repulsive force generated in the reaction force generating body 13 are kept small even if the reaction force generating body 13 is significantly deformed in the first direction Z. Therefore, even if the first member 12 and the second member 10 are significantly displaced relative to each other in the first direction Z, the surface pressure applied from the first pressure equalizing layer 14 to the second member 10 can be made less likely to vary within the plane where they abut against each other.

[0068] Next, a first embodiment of the battery pack will be described with reference to FIG.

[0069] The battery pack 2 of this embodiment includes a pair of end plates 21, 22 spaced apart in the first direction Z, a pressure mechanism 1, and a plurality of battery cells 23 stacked in the first direction Z. The pressure mechanism 1 and the plurality of battery cells 23 are disposed between the pair of end plates 21, 22.

[0070] In this embodiment, the first member is one of the end plates 21, 22 (end plate 21 in the illustrated example), and the second member is a plurality of battery cells 23. In this embodiment, the pressure mechanism 1 and the plurality of battery cells 23 are surrounded by the end plates 21, 22 and the bridge 25, and the plurality of battery cells 23 are assembled with an appropriate load applied between the end plates 21, 22. From this state, the reaction force generator 13 is compressed as the plurality of battery cells 23 expand, thereby generating a reaction force sufficient for the battery cells 23 to function appropriately as a battery.

[0071] The reaction force generator 13 of the pressure mechanism 1 abuts against one of the end plates 21 of the pair of end plates 21, 22. The reaction force generator 13 abuts against the surface of one of the end plates 21 that faces the battery cells 23. The pair of end plates 21, 22 are connected to each other in the first direction Z via a bridge 25. The end plates 21, 22 are made of a rigid material, such as a metal material, that minimizes deformation due to loads from the reaction force generator 13 and the battery cells 23.

[0072] The first pressure-equalizing layer 14 abuts against the battery cell 23 closest to one of the end plates 21 in the first direction Z. The first pressure-equalizing layer 14 abuts against the surface of this battery cell 23 facing the end plate 21. When a conductive material such as metal fiber or carbon fiber is used as the material of the first pressure-equalizing layer 14, an insulating layer is provided on one or both of the front surface 14b and back surface 14a of the first pressure-equalizing layer 14. The insulating layer is preferably a thin plate-like layer. Examples of materials for the insulating layer include polyethylene, polypropylene, silicone resin, phenolic resin, and epoxy resin. Alternatively, when the first pressure-equalizing layer 14 contains conductive fibers such as metal fiber or carbon fiber, the fibers themselves may be coated with an insulating coating.

[0073] A fire spread prevention plate 24 is provided between adjacent battery cells 23 in the first direction Z. The battery cells 23 expand and contract in the first direction Z as they are charged and discharged. At this time, the reaction force generator 13 elastically deforms in the first direction Z in response to the displacement of the battery cells 23, which are the second members.

[0074] As described above, in the battery pack 2 according to this embodiment, when the plurality of battery cells 23 expand, the pressure mechanism 1 applies a load to the plurality of battery cells 23 in the first direction Z via the first pressure equalizing layer 14 using the reaction force generated by the reaction force generator 13. This makes it possible to equalize the surface pressure applied to the battery cells 23 by the first pressure equalizing layer 14 within the contacting surfaces of the battery cells 23, thereby maintaining battery performance and preventing damage. When the plurality of battery cells 23 expand, the pressure mechanism 1 applies a load to the plurality of battery cells 23 via the first pressure equalizing layer 14. As a result, even if some of the plurality of battery cells 23 tend to tilt relative to the other battery cells 23, the reaction force generator 13 and the first pressure equalizing layer 14 deform, thereby preventing this tilt. Furthermore, this embodiment enables the weight of the battery pack 2 to be reduced and the installation space to be reduced, allowing the battery to perform at its best.

[0075] In the battery pack 2, the reaction force generator 13 is preferably a disc spring. When a disc spring is used in a region of its load-deflection characteristic curve that includes both a positive slope and a negative slope, or a region that includes a small positive or negative slope, fluctuations in the generated repulsive force are kept small even if the disc spring is significantly deformed in the first direction. Therefore, even if the battery cells 23 expand, the reaction force from the disc spring does not change significantly. This makes it possible to design the battery pack 2 so that the rigid body strength is reduced, and also makes it possible to extend the life of the battery cells 23.

[0076] Next, a second embodiment of the battery pack will be described with reference to Fig. 3. In this embodiment, the same components as those in the battery pack 2 of the first embodiment shown in Fig. 2 are denoted by the same reference numerals, and their description will be omitted, with only the differences being described.

[0077] In the battery pack 2a of this embodiment, a pressure mechanism 1a is provided between battery cells 23a, 23b adjacent to each other in the first direction Z. The battery cells 23a, 23b are a first member and a second member that sandwich the pressure mechanism 1a in the first direction Z. In this embodiment, the pressure mechanism 1a and the battery cells 23a, 23b are surrounded by an end plate 21 and a bridge 25, and the battery cells 23a, 23b are assembled between the end plates 21, 22 with an appropriate load applied. From this state, expansion of both or at least one of the two battery cells 23a, 23b sandwiching the pressure mechanism 1a compresses the reaction force generator 13, thereby generating a reaction force sufficient for the battery cells 23a, 23b to function appropriately as a battery.

[0078] Here, the pressure mechanism 1a of this embodiment further includes a second rigid plate 26 and a second pressure equalizing layer 27 in addition to the pressure mechanism 1 shown in FIGS.

[0079] The second rigid plate 26 is formed in a plate shape with its front and back surfaces facing the first direction Z, and is made of the same material and has the same dimensions as the first rigid plate 11. The second rigid plate 26 is provided on the opposite side of the first rigid plate 11 with the reaction force generator 13 sandwiched in the first direction Z. The front surface 11a of the first rigid plate 11 faces the back surface 26a of the second rigid plate 26 in the first direction Z. The reaction force generator 13 is in partial contact with the back surface 26a of the second rigid plate 26. The reaction force generator 13 is in contact with the back surface 26a of the second rigid plate 26 in a linear or intermittent distributed manner, for example. In the illustrated example, only the radially inner end of the outer peripheral surface 13b of the reaction force generator 13 is in contact with the back surface 26a of the second rigid plate 26 continuously around the entire circumference.

[0080] The second pressure-equalizing layer 27 is formed so that its front and back surfaces face the first direction Z, and is made of the same material, has the same basis weight, and has the same dimensions as the first pressure-equalizing layer 14. The second pressure-equalizing layer 27 is sandwiched in the first direction Z between the front surface 26b of the second rigid plate 26 and the battery cells 23a serving as first members. The second pressure-equalizing layer 27 distributes and transmits a load applied partially from the reaction force generator 13 to the back surface 26a of the second rigid plate 26 to the battery cells 23a serving as first members in a direction intersecting the first direction Z. The first pressure-equalizing layer 14 is sandwiched in the first direction Z between the first rigid plate 11 and the battery cells 23b serving as second members. The first pressure-equalizing layer 14 distributes and transmits a load applied partially from the reaction force generator 13 to the front surface 11a of the first rigid plate 11 to the battery cells 23b serving as second members in a direction intersecting the first direction Z.

[0081] In the battery pack 2a according to this embodiment, when one or both of the battery cells 23a, 23b expands, the pressure mechanism 1a applies a load to the battery cell 23a in the first direction Z via the second pressure equalizing layer 27 due to the reaction force generated by the reaction force generator 13. Therefore, even if the reaction force generator 13 partially abuts against the back surface 26a of the second rigid plate 26, the load partially applied to the back surface 26a of the second rigid plate 26 via the reaction force generator 13 can be dispersed in a direction intersecting the first direction Z by the second pressure equalizing layer 27 and transmitted to the battery cell 23a. As a result, the surface pressure applied to the battery cell 23a by the second pressure equalizing layer 27 can be made uniform within the abutting surface.

[0082] A pressure mechanism 1a including a second rigid plate 26 and a second pressure-equalizing layer 27 is provided between adjacent battery cells 23a, 23b in the first direction Z, and these battery cells 23a, 23b are defined as a first member and a second member. Therefore, the surface pressure applied by the reaction force generator 13 to each of the two battery cells 23a, 23b sandwiching the pressure mechanism 1a in the first direction Z can be made uniform within the mutual contact surfaces, thereby maintaining battery performance and preventing damage. Furthermore, according to this embodiment, tilt of the battery cells 23a, 23b due to expansion and contraction does not accumulate, and a load can be applied uniformly.

[0083] Next, a third embodiment of the battery pack will be described with reference to Fig. 4. In this embodiment, the same components as those in the battery pack 2 of the first embodiment shown in Fig. 2 are denoted by the same reference numerals, and their description will be omitted, with only the differences being described.

[0084] In the battery pack 2b of this embodiment, a third pressure equalizing layer 28 is provided between adjacent battery cells 23 in the first direction Z instead of the fire spread prevention plate 24. The third pressure equalizing layer 28 is formed so that its front and back surfaces face the first direction Z, and is formed of the same material, with the same basis weight, and with the same dimensions as the first pressure equalizing layer 14. The third pressure equalizing layer 28 is sandwiched in the first direction Z between adjacent battery cells 23 in the first direction Z.

[0085] In the battery pack 2b according to this embodiment, a third pressure equalizing layer 28 is provided between adjacent battery cells 23 in the first direction Z. This allows the surface pressure applied to the load-bearing members between the multiple battery cells 23 to be uniform within the mutual contact surfaces. This improves battery efficiency. It also improves the performance of the battery pack 2b and extends its lifespan. Furthermore, in this embodiment, the third pressure equalizing layer 28 allows the entire area of ​​each battery cell 23 to be used as a battery while minimizing increases in space and weight, thereby maximizing the functionality of each battery cell 23.

[0086] Next, a fourth embodiment of the battery pack will be described with reference to Fig. 5. In this embodiment, the same components as those in the battery pack 2b of the third embodiment shown in Fig. 4 are denoted by the same reference numerals, and their description will be omitted, with only the differences being described.

[0087] In the battery pack 2c of this embodiment, a fourth pressure equalizing layer 29 is provided between the other end plate 22 of the pair of end plates 21, 22 and a battery cell 23 adjacent to the end plate 22 in the first direction Z among the multiple battery cells 23. The fourth pressure equalizing layer 29 is formed so that its front and back surfaces face the first direction Z, and is formed of the same material and with the same basis weight as the first pressure equalizing layer 14. The fourth pressure equalizing layer 29 is sandwiched in the first direction Z between the end plate 22 and the battery cell 23 adjacent to the end plate 22 in the first direction Z.

[0088] In the battery pack 2c according to this embodiment, a fourth pressure equalizing layer 29 is provided between the other end plate 22 of the pair of end plates 21, 22 and a battery cell 23 of the plurality of battery cells 23 that is adjacent to the other end plate 22 in the first direction Z. This further improves the performance of the battery pack 2c and extends the life of the battery pack 2c. In addition, in this embodiment, the end plate 22 hardly experiences local deformation in response to the adjacent battery cell 23, but by sandwiching the fourth pressure equalizing layer 29 between the end plate 22 and the adjacent battery cell 23, it is possible to compensate for the difference in surface shape between the two.

[0089] As a modified example of this embodiment, when a fourth pressure equalizing layer 29 is provided for a battery pack 2a in which a pressure mechanism 1a is provided between adjacent battery cells 23a, 23b in the first direction Z as shown in Figure 3, it is preferable to provide the fourth pressure equalizing layer 29 on the inside of both end plates 21, 22.

[0090] 2 to 5 show all-solid-state batteries as the assembled batteries 2, 2a, 2b, and 2c including the battery cells 23, 23a, and 23b. However, the assembled batteries are not limited to these and may be solid-state batteries, semi-solid-state batteries, liquid-based batteries, or other secondary batteries. More preferably, the secondary batteries are all-solid-state batteries or liquid-based batteries. The ions contained in the battery cells 23, 23a, and 23b may be lithium ions, magnesium ions, sodium ions, or fluoride ions, with lithium ions being preferred. The battery cells 23, 23a, and 23b may be in the form of pouch-type batteries, square can-type batteries, or the like.

[0091] In the assembled batteries 2, 2a, 2b, and 2c, multiple pressure mechanisms 1, 1a may be provided at multiple locations that are different from each other in the first direction Z. For example, a pressure mechanism 1 may be provided near the other end plate 22 of the assembled battery 2 shown in FIG. 2 , thereby providing pressure mechanisms 1 on both ends of the assembled battery 2. Alternatively, the assembled battery 2a shown in FIG. 3 may be provided with an additional pressure mechanism 1a. In this case, the two pressure mechanisms 1a are not adjacent to each other, but sandwich at least one battery cell 23a, 23b between them. For the assembled battery 2 shown in FIG. 2, an additional pressure mechanism 1a shown in FIG. 3 may be provided between adjacent battery cells 23. Furthermore, when two or more pressure mechanisms 1, 1a are provided in the assembled batteries 2, 2a, 2b, and 2c, they are provided in a dispersed manner so that the pressure mechanisms do not contact each other in the first direction, and the orientation of the disc springs in the pressure mechanisms 1, 1a may be symmetrical so as to face each other, or may be the same. When two or more pressure mechanisms 1, 1a are provided for the assembled battery 2, 2a, 2b, 2c, the expansion and contraction of the battery cells 23, 23a, 23b at each location can be leveled out by the pressure mechanisms 1, 1a at multiple locations, making it easier to distribute the load evenly.

[0092] Next, an embodiment of the press device 3 having the pressurizing mechanism 1 will be described with reference to FIG.

[0093] The press device 3 of this embodiment includes a pair of pressure plates 31, 32 that are arranged to be able to move relatively close to and away from each other in the first direction Z, a pressurizing mechanism 1, and a pressed body 30. The pressurizing mechanism 1 and the pressed body 30 are arranged between the pair of pressurizing plates 31, 32.

[0094] In this embodiment, the pressing plate 31 is the first member, and the pressed body 30 is the second member. In this embodiment, a housing is assembled with a lower pressing plate 32 and two support columns 36, and a pressure mechanism 1 is attached below the upper pressing plate 31. The upper pressing plate 31, which is the first member, moves down along the two support columns 36 together with the pressure mechanism 1 to press the pressed body 30, which is the second member.

[0095] The reaction force generating body 13 of the pressure mechanism 1 is made up of a plurality of coil springs arranged in parallel. The reaction force generating body 13 abuts against the pressing plate 31. Two support columns 36 extend in the first direction Z and are arranged in parallel to each other. The pair of pressing plates 31, 32 are supported by the two support columns 36 so as to be able to move relatively close to and away from each other in the first direction Z. The pressing plates 31, 32 are made of a rigid material, such as a metal material, that minimizes deformation due to loads from the pressure mechanism 1 and the pressed body 30.

[0096] The pressed body 30 has an adhesive foil 33 and a pair of adherend members 34, 35 that sandwich the adhesive foil 33 in the first direction Z. The pair of adherend members 34, 35 are sandwiched in the first direction Z between the first pressure equalizing layer 14 and the pressing plate 32. The pressed body 30 is composed of a pair of adherend members 34, 35 that sandwich the adhesive foil 33 in the first direction Z. The adherend members 34, 35 are made of a metal material, a resin material, or the like. The first pressure equalizing layer 14 of the pressure mechanism 1 abuts against one adherend member 34 of the pair of adherend members 34, 35. A plurality of grooves 35a are formed on the surface of the other adherend member 35 that abuts against the adhesive foil 33.

[0097] With a pair of adherend members 34, 35 butted against each other in the first direction Z via the adhesive foil 33, a load is applied to the pressed body 30 by a pair of pressure plates 31, 32, melting the adhesive foil 33 and bonding the pair of adherend members 34, 35 to each other.

[0098] As described above, with the press device 3 according to this embodiment, when pressed by the pressing plate 31, the reaction force generated by the reaction force generator 13 of the pressing mechanism 1 applies a load in the first direction Z to the pressed body 30, which is the second member, via the first pressure-equalizing layer 14. Therefore, the surface pressure applied to the pressed body 30 by the first pressure-equalizing layer 14 can be made uniform within the abutting surfaces. The pressed body 30 is a pair of adherends 34, 35 sandwiching the adhesive foil 33 in the first direction Z, and the pair of adherends 34, 35 are sandwiched in the first direction Z between the first pressure-equalizing layer 14 and the pressing plate 32. Therefore, in each of the pair of adherends 34, 35, the abutting surfaces sandwiching the adhesive foil 33 in the first direction Z can be bonded uniformly with little bias.

[0099] In this example, the press device 3 is a joining device that bonds a pair of adherend members 34, 35 sandwiching an adhesive foil 33 in the first direction Z, but it may also be a device that performs plastic processing, cutting processing, etc.

[0100] <First verification test> Here, each of the multiple types of pressure-equalizing layers was incorporated into the pressure mechanism 1, and in a compression testing machine, a load of 5000 N was applied from the first member, the pressure-applying rigid plate, to the base plate via the pressure mechanism 1 (reaction force generator, first rigid plate, first pressure-equalizing layer) and the surface pressure distribution sensor (pressure measurement film). The distribution of surface pressure applied from the first pressure-equalizing layer to the surface pressure distribution sensor (pressure measurement film) on the base plate, the second member, was measured.

[0101] A disc spring with an outer diameter of 45 mm was used as the reaction force generator, a square plate made of alloy tool steel (SKD11) with a thickness of 5 mm and a side length of 50 mm was used as the pressurizing rigid plate and the first rigid plate 11, and a square plate with a thickness of 5 mm and a side length of 50 mm was used as the first pressure equalizing layer. Figure 7 shows an enlarged view of the first pressure equalizing layer used in the first verification test, and Figure 8 shows the obtained surface pressure distribution (0 MPa (white) to 3 MPa (black)). For reference, Figure 8 shows the distribution of surface pressure applied to a surface pressure distribution sensor (pressure measurement film) on a surface plate in a pressurizing mechanism without a first pressure equalizing layer.

[0102] <Not Applicable as First Pressure-Equalizing Layer> When the first pressure-equalizing layer is a rubber plate, it is incompressible, so when pressed, the center becomes hydrostatically pressurized, resulting in unevenly high surface pressure in the center. When the first pressure-equalizing layer is made of glass cloth (flat knit) or stainless steel mesh (flat knit), the fibers are woven in a straight line, making them less likely to move, and the overlapping portions of the warp and weft threads preferentially come into contact and transmit the load. Therefore, the contact area is small, making it difficult for the first pressure-equalizing layer to distribute the load from the first rigid plate 11, resulting in unevenly high surface pressure in some areas. From the above, it was confirmed that rubber plate, glass cloth (flat knit), and stainless steel mesh (flat knit) are not applicable as first pressure-equalizing layers.

[0103] <Applicability as First Pressure-Equalizing Layer> When the first pressure-equalizing layer is glass wool, the short glass fibers are randomly bonded in a cotton-like pattern, providing voids through which the fibers can move. This makes it easier for the first pressure-equalizing layer to distribute the load from the first rigid plate 11, thereby suppressing the unevenness of the surface pressure to some extent. When the first pressure-equalizing layer is aluminum nonwoven fabric, the aluminum fibers are randomly entangled and bonded, providing voids through which the fibers can move. This makes it easier for the first pressure-equalizing layer to distribute the load from the first rigid plate 11, thereby suppressing the unevenness of the surface pressure to some extent. When the first pressure-equalizing layer is a mesh spring, the stainless steel fibers are woven in a meandering pattern with a melius weave, providing voids through which the fibers can move. This makes it easier for the first pressure-equalizing layer to distribute the load from the first rigid plate 11, thereby suppressing the unevenness of the surface pressure to some extent. From the above, it was confirmed that glass wool, aluminum nonwoven fabric, and mesh spring are applicable as the first pressure-equalizing layer. Glass wool, aluminum nonwoven fabric, and mesh springs have a distribution of fiber densities, and since they actively transmit load from the dense parts, there is a slight imbalance in the pressure distribution due to the imbalance in the fiber densities, but this imbalance is within the acceptable range and therefore they are considered applicable as the first pressure equalizing layer.

[0104] <Recommended for Use as a First Pressure-Equalizing Layer> When the first pressure-equalizing layer is a glass fiber wet-laid nonwoven fabric, the glass fibers are randomly entangled and partially bonded together with a binder or the like, providing voids through which the fibers can move. This facilitates the load from the first rigid plate 11 to be distributed by the first pressure-equalizing layer, thereby suppressing uneven surface pressure. When the first pressure-equalizing layer is a cork sheet, the cellular structure of the cork tissue provides elasticity and voids, thereby facilitates the load from the first rigid plate 11 to be distributed by the first pressure-equalizing layer, thereby suppressing uneven surface pressure. When the first pressure-equalizing layer is a sponge sheet, the flexibility and voids provide elasticity and voids, thereby facilitates the load from the first rigid plate 11 to be distributed by the first pressure-equalizing layer, thereby suppressing uneven surface pressure. From the above, it has been confirmed that glass fiber wet-laid nonwoven fabric, cork sheet, and sponge sheet are recommended for use as first pressure-equalizing layers.

[0105] <Second Verification Test> When a glass fiber wet-laid nonwoven fabric was used as the first pressure-equalizing layer, the surface pressure distribution and load characteristics were measured for different basis weights of the first pressure-equalizing layer. Specifically, first pressure-equalizing layers with different basis weights were each incorporated into the pressure mechanism 1, and in a compression testing machine, a load of 5000 N was applied from the first member, the rigid pressure plate, to the pressure mechanism 1 (reaction force generator, first rigid plate, first pressure-equalizing layer) and the surface pressure distribution sensor, via the surface pressure distribution sensor, in the first direction Z. The surface pressure distribution applied from the first pressure-equalizing layer to the surface pressure distribution sensor on the surface plate, the second member, was measured. Furthermore, based on the results of the surface pressure distribution measurement, the surface pressure variation coefficient was calculated. The surface pressure variation coefficient is the standard deviation of the surface pressure distribution divided by the average surface pressure. A smaller surface pressure variation coefficient indicates less surface pressure bias.

[0106] The reaction force generator was a stainless steel (SUS304) disc spring with an outer diameter of 45 mm, an inner diameter of 22.4 mm, a thickness of 2.5 mm, and a height of 3.5 mm. The pressurizing rigid plate and the first rigid plate were square carbon steel (S50C) plates with a thickness of 5 mm and a side length of 50 mm. The first equalizing layer was a square plate with a side length of 50 mm. The test conditions were: the load applied from the pressurizing rigid plate to the surface plate was 0 to 5000 N, the zero load was 0.5 N, the feed rate was 5 mm / s, the maximum load was held for 30 seconds, and the ambient temperature was room temperature.

[0107] Figure 9 is a graph showing the correlation between the basis weight of the first equalizing layer and the coefficient of variation of the surface pressure in the second verification test. In Figure 9, the vertical axis represents the coefficient of variation of the surface pressure, and the horizontal axis represents the basis weight of the first equalizing layer. Figure 9 also shows an approximation curve that represents the correlation between the basis weight of the first equalizing layer and the coefficient of variation of the surface pressure. As shown in Figure 9, it was confirmed that the larger the basis weight of the first equalizing layer, the smaller the coefficient of variation of the surface pressure, and the more effectively the bias in the surface pressure can be suppressed. Furthermore, when the basis weight of the first equalizing layer is 50 g / m ２ It was confirmed that when the basis weight of the first pressure equalizing layer is 50 g / m or more, the coefficient of variation of the surface pressure becomes sufficiently small, and the bias of the surface pressure can be suppressed. ２ It is preferable that the weight is 60 g / m or more. ２ More preferably, it is 70 g / m or more. ２ More preferably, it is 80 g / m or more. ２ It is clear that the above is most preferable.

[0108] <Third Verification Test> The surface pressure distribution was measured for a battery pack provided with a pressure equalizing layer. Specifically, a battery pack for verification of Example 1 was prepared, which included a pair of end plates 21, 22, a pressure applying mechanism 1 (reaction force generator 13, first rigid plate 11, first pressure equalizing layer 14), and five dummy cells as substitutes for battery cells 23. The five dummy cells were stacked in the first direction Z. The pressure applying mechanism 1 and the five dummy cells were provided between the pair of end plates 21, 22. Hereinafter, the dummy cell closest to the end plate 21 will be referred to as the first dummy cell, and the dummy cells from the first dummy cell toward the end plate 22 will be referred to as the second to fifth dummy cells. The first pressure equalizing layer 14 was provided between the first rigid plate 11 and the first dummy cell. In Example 1, a fire spread prevention plate 24 was provided between adjacent dummy cells in the first direction Z. The dummy cells (battery cells 23) were made of high-density polyethylene (HDPE) in a square shape with a side length of 70 mm and a thickness of 1 mm. The first pressure equalizing layer 14 was made of a 140 g / m² board. ２A wet-laid nonwoven fabric of glass fiber was used. A mica sheet was used as the fire spread prevention plate 24. Surface pressure distribution sensors (pressure measurement films) were installed between the first dummy cell and the first pressure equalizing layer 14 above it, between the third dummy cell and the fire spread prevention plate 24 above it, and between the fifth dummy cell and the fire spread prevention plate 24 above it. When a load of 14,700 N was applied in the first direction Z from the end plate 21 (the first member) to the end plate 22 using a compression testing machine, the distribution of surface pressure applied from the first pressure equalizing layer 14 to the surface pressure distribution sensor on the first dummy cell, the distribution of surface pressure applied from the fire spread prevention plate 24 to the surface pressure distribution sensor on the third dummy cell, and the distribution of surface pressure applied from the fire spread prevention plate 24 to the surface pressure distribution sensor on the fifth dummy cell were measured. Furthermore, as a verification battery pack for Example 2, a battery pack was prepared in which a third pressure equalizing layer 28 was provided between dummy cells adjacent to each other in the first direction Z instead of the fire spread prevention plate 24. Furthermore, surface pressure distribution sensors were installed between the first dummy cell and the first pressure equalizing layer 14 above it, between the third dummy cell and the third pressure equalizing layer 28 above it, and between the fifth dummy cell and the third pressure equalizing layer 28 above it. When a load of 5000 N was applied in the first direction Z from the end plate 21 (the first member) to the end plate 22 using a compression testing machine, the distribution of surface pressure applied from the first pressure equalizing layer 14 to the surface pressure distribution sensor on the first dummy cell, the distribution of surface pressure applied from the third pressure equalizing layer 28 to the surface pressure distribution sensor on the third dummy cell, and the distribution of surface pressure applied from the third pressure equalizing layer 28 to the surface pressure distribution sensor on the fifth dummy cell were measured. Furthermore, a battery pack without a first pressure equalizing layer was prepared as a comparative example verification battery pack. That is, in the comparative example verification battery pack, a first pressure equalizing layer was not provided between the first rigid plate 11 and the first dummy cell, and the first rigid plate 11 and the first dummy cell were in contact with each other. The other configurations of the comparative example verification battery pack were the same as those of the first example verification battery pack. Surface pressure distribution sensors were installed between the first dummy cell and the first rigid plate 11 above it, between the third dummy cell and the fire spread prevention plate 24 above it, and between the fifth dummy cell and the fire spread prevention plate 24 above it.In the compression testing machine, when a load of 5000 N was pressed in the first direction Z from the first member, end plate 21, to end plate 22, the distribution of surface pressure applied from the first rigid plate 11 to the surface pressure distribution sensor on the first dummy cell, the distribution of surface pressure applied from the fire spread prevention plate 24 to the surface pressure distribution sensor on the third dummy cell, and the distribution of surface pressure applied from the fire spread prevention plate 24 to the surface pressure distribution sensor on the fifth dummy cell were measured.

[0109] FIG. 10 shows the surface pressure distribution obtained in the third verification test (0 MPa (white) to 5 MPa (black)). In Example 1, it was confirmed that by dispersing the load from the first rigid plate 11 using the first pressure equalizing layer 14, it was possible to suppress the bias in the surface pressure in the first dummy cell, the third dummy cell, and the fifth dummy cell compared to the comparative example. In addition, in Example 2, it was confirmed that by providing the third pressure equalizing layer 28 between the dummy cells adjacent to each other in the first direction Z, it was possible to more effectively suppress the bias in the surface pressure in the first dummy cell, the third dummy cell, and the fifth dummy cell.

[0110] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0111] For example, in the above embodiment, the second pressure equalizing layer 27, the third pressure equalizing layer 28, and the fourth pressure equalizing layer 29 are formed from the same material and with the same basis weight as the first pressure equalizing layer 14. However, the second pressure equalizing layer 27, the third pressure equalizing layer 28, and the fourth pressure equalizing layer 29 may be formed from a material and basis weight different from those of the first pressure equalizing layer 14, as long as they are made of a material recommended for use as described above.

[0112] The battery pack 2 a of the second embodiment may be provided with the third pressure equalizing layer 28, the fourth pressure equalizing layer 29, or both the third pressure equalizing layer 28 and the fourth pressure equalizing layer 29. Furthermore, the battery pack 2 of the first embodiment may be provided with the fourth pressure equalizing layer 29.

[0113] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention, and the above-described embodiments and variations may be combined as appropriate.

[0114] According to the present invention, it is possible to provide a pressure mechanism, a battery pack, and a press device that can make the surface pressure applied to members that are subjected to a load uniform within the surfaces where the members abut against each other.

[0115] REFERENCE SIGNS LIST 1, 1a Pressurizing mechanism 2, 2a Battery pack 3 Pressing device 10 Second member 11 First rigid plate 11a Surface of first rigid plate (surface facing first member) 11b Back surface of first rigid plate 12 First member 12a Back surface of first member (surface facing second member) 13 Reaction force generating body 14 First pressure equalizing layer 14b Surface of first pressure equalizing layer (surface pressed against second member) 21 One end plate (first member) 22 Other end plate 23 Multiple battery cells (second member) 23a Battery cell (first member) 23b Battery cell (second member) 26 Second rigid plate 26a Back surface of second rigid plate 27 Second pressure equalizing layer 28 Third pressure equalizing layer 29 Fourth pressure equalizing layer 30 Pressurized body (second member) 31 One pressing plate (first member) Z first direction

Claims

1. A pressure mechanism provided between a first member and a second member that face each other in a first direction and the distance between them changes, comprising: a reaction force generating body that elastically deforms in response to displacement of the first member or the second member; a first rigid plate that is positioned closer to the second member than the reaction force generating body; and a first pressure equalizing layer that is sandwiched between the first rigid plate and the second member in the first direction, wherein the reaction force generating body partially abuts against the surface of the first rigid plate that faces the first member, and the first pressure equalizing layer distributes and transmits the load that is partially applied to the first rigid plate from the reaction force generating body to the second member in a direction that intersects the first direction.

2. A pressure mechanism as described in claim 1, wherein a large number of voids are provided over the entire area of ​​the first pressure equalizing layer in a direction intersecting the first direction, at least on the surface side pressed against the second member.

3. The pressure mechanism according to claim 2, wherein the numerous voids are provided over the entire area of ​​the first pressure equalizing layer in the first direction.

4. The pressure mechanism according to claim 2, wherein the first pressure equalizing layer contains metal fiber, glass fiber, pulp, resin fiber, or carbon fiber.

5. The pressure mechanism according to claim 4, wherein the first pressure-equalizing layer is made of glass nonwoven fabric, glass wool, or metal fiber nonwoven fabric, in which the fibers are bonded by at least one of random entanglement, adhesion, fusion, and sintering, or a melius-knitted mesh spring.

6. The pressure mechanism according to claim 4, wherein the first pressure equalizing layer is made of a wet-laid nonwoven fabric.

7. The first pressure-equalizing layer is a wet-laid nonwoven fabric whose main material is glass fiber, and the basis weight of the first pressure-equalizing layer is 50 g / m ２ The pressure mechanism according to claim 6 .

8. A pressure mechanism according to claim 2, wherein the first pressure equalizing layer is made of a cork sheet or a sponge sheet.

9. A pressure mechanism as described in claim 3, wherein fine irregularities are formed on the first rigid plate, and the thickness of the first pressure-equalizing layer is greater than the maximum height difference in the first direction of the fine irregularities.

10. The pressure mechanism according to claim 1, wherein the reaction force generating body is a disc spring.

11. A pressure mechanism according to any one of claims 1 to 8, wherein the reaction force generating body abuts against a surface of the first member facing the second member.

12. A pressure applying mechanism as described in any one of claims 1 to 8, further comprising: a second rigid plate located closer to the first member than the reaction force generating body; and a second pressure equalizing layer sandwiched in the first direction between the second rigid plate and the first member, wherein the reaction force generating body partially abuts against the surface of the second rigid plate facing the second member, and the second pressure equalizing layer distributes and transmits the load partially applied from the reaction force generating body to the second rigid plate in a direction intersecting the first direction to the first member.

13. A battery pack comprising: a pair of end plates spaced apart in the first direction; a plurality of battery cells stacked in the first direction; and at least one pressure mechanism, wherein the pressure mechanism is the pressure mechanism described in claim 1, and the pressure mechanism and the plurality of battery cells are disposed between the pair of end plates.

14. The battery pack described in claim 13, wherein at least one pressure mechanism is provided between the pair of end plates and the plurality of battery cells, the first member for one of the at least one pressure mechanism is one of the pair of end plates, the second member is the plurality of battery cells, and the reaction force generator abuts against a surface of the one end plate facing the second member.

15. The battery pack according to claim 13 or 14, wherein the at least one pressure mechanism is provided between at least one of the plurality of battery cells adjacent in the first direction, and the battery cells adjacent in the first direction are the first member and the second member for one of the at least one pressure mechanism, and the pressure mechanism further comprises: a second rigid plate located closer to the first member than the reaction force generator; and a second pressure equalizing layer sandwiched in the first direction between the second rigid plate and the first member, and the reaction force generator partially abuts against the surface of the second rigid plate facing the second member, and the second pressure equalizing layer distributes and transmits the load partially applied from the reaction force generator to the second rigid plate to the first member in a direction intersecting the first direction.

16. The battery pack according to any one of claims 13 to 15, wherein a third voltage equalizing layer is provided between adjacent battery cells in the first direction among the plurality of battery cells.

17. The battery pack described in any one of claims 13 to 16, wherein a fourth pressure equalizing layer is provided between the pair of end plates and at least one battery cell of the plurality of battery cells that is adjacent to the other end plate of the pair of end plates in the first direction.

18. A press device comprising: a pressure plate; a pressed body; and the pressure mechanism described in claim 11, wherein the pressure mechanism is provided between the pressure plate and the pressed body, the first member is the pressure plate, and the second member is the pressed body.

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