JP7562228B2 - Cushioning material - Google Patents

Description

This disclosure relates to a cushioning material used in a battery pack composed of multiple single cells.

A flat plate-shaped cushioning material is known that is sandwiched between cells to prevent them from coming into contact with each other (see, for example, Patent Document 1).

JP 4508221 A (paragraphs [0016] to [0020])

In a battery pack, if the temperature of the cells is adjusted to an appropriate temperature, the decrease in charge/discharge efficiency and the shortening of the battery life can be suppressed. However, the conventional cushioning materials mentioned above have the problem that it is difficult to adjust the temperature of the cells.

A first aspect of the invention made to solve the above problems is a cushioning material that is sandwiched between cells that make up a battery pack, the cushioning material being in partial contact with the cells and having an uneven surface that forms an air space that passes between the cushioning material and the cells.

A second aspect of the present invention is the cushioning material according to the first aspect , wherein the uneven surface is provided with grooves that form the ventilation spaces.

A third aspect of the present invention is the cushioning material according to the second aspect , wherein the groove is disposed so as to extend vertically.

A fourth aspect of the present invention is the cushioning material according to the second or third aspect, wherein a plurality of the grooves are provided on the uneven surface and are parallel to each other.

A fifth aspect of the invention is the cushioning material according to the fourth aspect , wherein the grooves are provided on the uneven surfaces on both the front and back of the cushioning material, and are arranged so that they alternate on the front and back.

A sixth aspect of the invention is the cushioning material according to any one of the first to fifth aspects, in which a high heat transfer layer, which is in contact with the single battery and has a higher thermal conductivity than the foamed resin layer, is laminated on the foamed resin layer.

A seventh aspect of the present invention is the buffer material according to the sixth aspect , wherein the highly heat-conductive layer is a metal layer.

In the first aspect of the invention , an uneven surface is provided that is in partial contact with the unit cells, and this uneven surface forms a ventilation space that passes between the buffer material and the unit cells. Therefore, it is possible to dissipate heat transferred from the unit cells to the buffer material to the outside of the buffer material through the ventilation space, or to introduce warm air from the outside into the ventilation space to transfer heat to the unit cells. This makes it easy to adjust the temperature of the unit cells through the ventilation space.

The uneven surface may be provided with grooves that form ventilation spaces ( a second aspect of the invention ). In this case, for example, the cells may be arranged horizontally, and the buffer material may be arranged so that the grooves extend vertically ( a third aspect of the invention ). With this arrangement, ventilation spaces between the buffer material and the cells are formed to extend vertically, so that hot air from the buffer material and the cells can easily escape upward, facilitating heat dissipation.

The grooves may be provided in a plurality of parallel grooves on the uneven surface ( fourth aspect of the invention ). This configuration allows cold and warm air to flow in one direction, making it easier to regulate the temperature of the cells. The parallel grooves may be provided on both surfaces of the cushioning material that come into contact with the cells on both sides (i.e., on both the front and back). In this case, the grooves may be arranged so that they alternate on the uneven surfaces on the front and back of the cushioning material ( fifth aspect of the invention ). This configuration allows the thickness of the cushioning material with grooves to be constant, making it possible to reduce the variation in the reaction force applied from the cushioning material to the cells within the surface of the cell facing the cushioning material.

In the sixth aspect of the invention , the foamed resin layer can improve the cushioning properties. In addition, by having the foamed resin layer, it is possible to suppress heat transfer between the unit cells sandwiching the cushioning material. As a result, even if some unit cells become hot due to an abnormality or the like, it is possible to suppress heat transfer to the other unit cells. In addition, in the sixth aspect of the invention , a high heat transfer layer having a higher thermal conductivity than the foamed resin layer is laminated on the foamed resin layer as the outermost layer and contacts the unit cells. Therefore, it is possible to improve the heat transfer between the cushioning material and the unit cells, making it easier to adjust the temperature of the unit cells. As an example of the high heat transfer layer, a metal layer can be mentioned ( seventh aspect of the invention ).

FIG. 1 is a perspective view of a battery pack in which a cushioning material according to the present disclosure is sandwiched between unit cells; Perspective view of the cushioning material Cross-section of the cushioning material Cross-sectional view of battery pack A partially cutaway perspective view of the cushioning material sandwiched between the unit cells. Cross-sectional view of a battery pack when a single cell expands FIG. 13 is a perspective view of a cushioning material according to another embodiment; FIG. 13 is a cross-sectional plan view of a battery pack in which the cushioning material is sandwiched between unit cells according to another embodiment; FIG. 13 is a perspective view of a cushioning material according to another embodiment; FIG. 13 is a cross-sectional plan view of a battery pack in which a cushioning material according to another embodiment is sandwiched between unit cells.

[First embodiment]
As shown in FIGS. 1 and 2 , the cushioning material 10 of this embodiment has a sheet shape that is, for example, generally rectangular in plan view, and is assembled to the battery pack 50 .

In detail, in this embodiment, the battery pack 50 is formed by stacking multiple roughly rectangular plate-like cells 51 in the thickness direction, and the cushioning material 10 is sandwiched between adjacent cells 51. For example, the cells 51 are stacked horizontally, and the battery pack 50 is installed in a vehicle such as a car. An electrode portion 52 protrudes from one end face in the longitudinal direction of each cell 51, and the multiple cells 51 are arranged so that the electrode portions 52 face the same side (upward in FIG. 1).

2 and 3, the cushioning material 10 has an uneven surface 20 on both the front and back sides that come into contact with the single battery 51. In this embodiment, the uneven surface 20 has a groove 30 formed therein. Specifically, the groove 30 is linear and crosses the uneven surface 20, and both ends are open at the outer edge of the cushioning material 10. In addition, a plurality of grooves 30 are provided on each uneven surface 20 and are arranged parallel to each other. In this embodiment, the grooves 30 extend in the same direction on the front and back uneven surfaces 20 (more specifically, they extend in the long side direction of the cushioning material 10, for example). In this embodiment, the grooves 30 are angular grooves (more specifically, angular grooves with a rectangular cross section), but they may be round grooves, U-grooves, triangular grooves, etc.

In this embodiment, as shown in FIG. 3, the grooves 30 are arranged alternately on the uneven surfaces 20 on the front and back of the cushioning material 10. That is, the grooves 30 on one uneven surface 20 on the front and back of the cushioning material 10 and the grooves 30 on the other uneven surface 20 are arranged shifted in the arrangement direction of the grooves 30 so as not to overlap when viewed from the thickness direction of the cushioning material 10. In addition, in this embodiment, the width of the grooves 30 and the spacing between the grooves 30 are approximately the same on each uneven surface 20, and the thickness of the cushioning material 10 is approximately constant. In detail, the depths of the multiple grooves 30 are approximately the same, and the bank surface 33, which is the part of the uneven surface 20 of the cushioning material 10 excluding the grooves 30, is arranged on approximately the same plane on each uneven surface 20 and is approximately parallel to the bottom surface of the groove 30. The bank surface 33 is the protruding tip surface of the bank portion that is relatively raised from the bottom surface of the groove 30.

As shown in FIG. 3, the cushioning material 10 is formed by laminating a high heat transfer layer having a higher thermal conductivity than the foamed resin layer 11 on a foamed resin layer 11 in which a groove 30 is formed. In this embodiment, a metal layer 21 is provided as this high heat transfer layer. Note that a resin layer having a higher thermal conductivity than the foamed resin layer 11 may also be provided as the high heat transfer layer.

The foamed resin layer 11 can be made of, for example, a polyurethane-based resin foam, a polyolefin-based resin foam, an acrylic-based resin foam, or a combination of these foams. The foamed resin layer 11 may have an open cell structure or a closed cell structure.

In this embodiment, a high-density layer is formed on the outermost surface of the foamed resin layer 11, and has a higher density (apparent density) than the inner portion of the outermost surface.

In this embodiment, the metal layer 21 is provided on both the front and back sides of the foamed resin layer 11, and is laminated on the high-density layer of the foamed resin layer 11. It is preferable that the metal layer 21 is disposed at least on the bank surface 33 of the uneven surface 20 of the cushioning material 10, and in this embodiment, it is disposed only on the bank surface 33.

The metal layer 21 may be made of metal foil, may be formed by metal vapor deposition, or may be formed by metal spraying.

The grooves 30 may be formed in the foamed resin layer 11 of the cushioning material 10 by mold foam molding, by hot press molding a flat foam sheet, or by cutting a flat foam sheet. In mold foam molding or hot press molding, it is easy to form the above-mentioned high density layer in the foamed resin layer 11. As the high density layer of the foamed resin layer 11, a skin layer is formed in the case of mold foam molding, and a molten skin layer is formed by melting the outer surface of the foamed sheet in the case of hot press molding. Here, a high density layer having a higher density (apparent density) than the part inside the outermost part may or may not be provided on the outermost part of the front or back of the foamed sheet before hot press molding or cutting. In addition, in mold foam molding or hot press molding, the metal layer 21 may be laminated on the foamed resin layer 11 after molding the foamed resin layer 11, or molding the foamed resin layer 11 and laminating the metal layer 21 may be performed simultaneously.

As shown in FIG. 1, when the cushioning material 10 is assembled to the battery pack 50, the cushioning material 10 is sandwiched between the cells 51 in the thickness direction. At this time, the cushioning material 10 is arranged so that the grooves 30 extend vertically. In addition, the uneven surface 20 of the cushioning material 10 contacts the cells 51. Here, the uneven surface 20 partially contacts the cells 51 (specifically, the bank surface 33 contacts the cells 51), and the inner part of the grooves 30 forms an air space S (an air passage in this embodiment) between the cushioning material 10 and the cells 51 (see FIG. 4). The air space S extends linearly in the vertical direction and both ends are open at the outer periphery of the cushioning material 10 (see FIG. 5).

If the thickness of the foamed resin layer 11 is set to be equal to or greater than the distance between the cells 51, the elastic force of the foamed resin layer 11 can press the uneven surface 20 against the cells 51. This allows the buffer material 10 and the cells 51 to be in close contact with each other, and allows heat from the cells 51 to be efficiently transferred to the buffer material 10. In detail, the cells 51 expand and contract with charging and discharging. Therefore, if the thickness of the foamed resin layer 11 is set to be equal to or greater than the distance between the cells 51 when the two cells 51 sandwiching the buffer material 10 contract together, the metal layer 21 can always be in contact with the cells 51. In addition, the grooves 30 of the uneven surface 20 are deep enough not to be filled even when the cells 51 expand (see FIG. 6).

However, the cell 51 of the battery pack 50 has a suitable temperature range for exhibiting stable battery performance, but since the cell 51 generates or absorbs heat during charging and discharging, when it generates heat during charging and discharging, it is necessary to dissipate the heat of the cell 51 to the outside. In this embodiment, the cushioning material 10 contacts the cell 51, so that the heat of the cell 51 can be transferred from the metal layer 21 to the cushioning material 10. Here, if the heat transferred to the cushioning material 10 is not easily dissipated to the outside, the heat may be trapped in the cushioning material 10, making it difficult to adjust the temperature of the cell 51 to an appropriate temperature. In contrast, the cushioning material 10 of this embodiment has an uneven surface 20 that is partially in contact with the cell 51, and this uneven surface 20 forms a ventilation space S that passes between the cushioning material 10 and the cell 51. Therefore, it is possible to dissipate heat transferred from the single battery 51 to the cushioning material 10 through the ventilation space S, or to take in warm air from the outside into the ventilation space S and transfer the heat to the single battery 51. This makes it easy to adjust the temperature of the single battery 51 through the ventilation space S of the cushioning material 10.

In addition, in this embodiment, the cushioning material 10 is arranged so that the grooves 30 extend in the vertical direction. Therefore, the ventilation space S between the cushioning material 10 and the single battery 51 is formed to extend vertically, and hot air from the cushioning material 10 and the single battery 51 can easily escape upward, facilitating heat dissipation. In addition, a plurality of grooves 30 are provided on the uneven surface 20 and are parallel to each other. This makes it easier for cold air and warm air to flow in one direction, making it easier to adjust the temperature of the single battery 51. Furthermore, a plurality of grooves 30 that are parallel to each other are provided on both the front and back uneven surfaces 20 of the cushioning material 10, and are arranged so that the grooves 30 are staggered on the front and back uneven surfaces 20. This makes it possible to make the thickness of the cushioning material 10 (foamed resin layer 11) having the grooves 30 constant, and makes it possible to reduce the variation in the reaction force (elastic force) applied from the cushioning material 10 within the surface of the single battery 51 facing the cushioning material 10.

In the cushioning material 10 of this embodiment, the foamed resin layer 11 can enhance the cushioning properties. In addition, the foamed resin layer 11 has an air layer made of air in the bubbles, which can suppress heat transfer between the cells 51 sandwiching the cushioning material 10 (heat transfer in the thickness direction of the foamed resin layer 11). As a result, even if the temperature of some of the cells 51 rises excessively, it is possible to suppress the temperature rise of the surrounding cells 51. In addition, a high heat transfer layer (metal layer 21) having a higher thermal conductivity than the foamed resin layer 11 is laminated on the foamed resin layer 11, and this metal layer 21 comes into contact with the cells 51. Therefore, the heat transfer between the cushioning material 10 and the cells 51 can be improved, making it easier to adjust the temperature of the cells 51.

[Other embodiments]
(1) In the above embodiment, the metal layer 21 is provided, but the metal layer 21 does not have to be provided. In this case, by providing a high-density layer (skin layer or molten film layer) on the foamed resin layer 11, it is possible to improve the adhesion between the unit cell 51 and the buffer material 10, and it is possible to improve the heat transfer between the unit cell 51 and the buffer material 10. In addition, the metal layer 21 may be provided only on one side of the buffer material 10, either the front or the back.

(2) As shown in FIG. 7, the uneven surface 20V may have a flat surface with a plurality of grooves 30V formed in a lattice pattern, as in the cushioning material 10V. In this configuration, the grooves 30V can form air passages, for example, in the long and short side directions of the cushioning material 10V, making it easier to adjust the temperature of the battery cells 51.

(3) The cushioning material 10W may be in the form of a generally corrugated sheet, as shown in Fig. 8 (A) and Fig. 8 (B). Even in this configuration, alternating grooves 30W are formed on the front and back of the cushioning material 10W, and the grooves 30W make it possible to form a ventilation space S between the cushioning material 10 and the single battery 51.

(4) As shown in Figs. 9 and 10, the cushioning material 10X may have an uneven surface 20X (so-called profile) in which a large number of raised portions 32X are arranged, for example, in a houndstooth pattern. In this case, the ventilation space S formed between the uneven surface 20X and the single battery 51 can be configured to be ventilated in multiple directions perpendicular to the thickness direction of the cushioning material 10X. Note that, in the uneven surfaces 20X on the front and back of the cushioning material 10X, the raised portions 32X may be arranged so as to overlap in the thickness direction of the cushioning material 10X, or may be arranged so as to be offset so as not to overlap in the thickness direction of the cushioning material 10X.

(5) In the above embodiment, both the front and back surfaces of the cushioning material 10 are uneven surfaces 20, but only one of the surfaces may be uneven surfaces 20. In this case, for example, the other surface may be a flat surface, and no ventilation space S may be formed between the battery cell 51 and the other surface.

(6) In the above embodiment, multiple grooves 30 are provided on the uneven surface 20, but only one may be provided. Note that when multiple grooves 30 are provided on the uneven surface 20, the shapes and dimensions (width, depth, etc.) of the grooves 30 do not all need to be the same.

(7) In the above embodiment, the grooves 30 were staggered on the front and back of the cushioning material 10, but they may also overlap in the thickness direction of the cushioning material 10.

(8) In the above embodiment, the grooves 30 extend in the same direction on the front and back of the cushioning material 10, but they may extend in different directions.

(9) In the above embodiment, an elastic layer made of rubber or the like may be provided instead of the foamed resin layer 11.

(10) In the above embodiment, the metal layer 21 was disposed only on a portion of the uneven surface 20 (bank surface 33), but it may also be disposed inside the groove 30 (bottom surface and side surface), or may be disposed on the entire uneven surface 20.

REFERENCE SIGNS LIST 10: Cushioning material 11: Foamed resin layer 20: Uneven surface 21: Metal layer 30: Groove 50: Battery pack 51: Single cell S: Ventilation space

Claims (4)

A cushioning material including a foamed resin layer sandwiched between unit cells constituting a battery pack,
a concave-convex surface that is in partial contact with the battery cell and forms a ventilation space that passes between the buffer material and the battery cell;
the uneven surface has grooves that form the ventilation space,
The cushioning material is formed by laminating a high heat transfer layer, which is in contact with the cell and has a thermal conductivity higher than that of the foamed resin layer, on the foamed resin layer up to the inside of the groove. A cushioning material including a foamed resin layer sandwiched between unit cells constituting a battery pack,
a concave-convex surface that is in partial contact with the battery cell and forms a ventilation space that passes between the buffer material and the battery cell;
the uneven surface has grooves that form the ventilation space,
The foamed resin layer is a cushioning material having an outermost high density layer which has a higher density than the inner part. A cushioning material sandwiched between cells constituting a battery pack,
a concave-convex surface that is in partial contact with the battery cell and forms a ventilation space that passes between the buffer material and the battery cell;
A cushioning material comprising a foamed resin layer and a metal layer, which is in contact with the cell and has a higher thermal conductivity than the foamed resin layer, laminated on the foamed resin layer. The cushioning material according to claim 1 or 3,
A buffer material, wherein the highly heat-conductive layer according to claim 1 or the metal layer according to claim 3 is a layer formed by metal vapor deposition or metal spraying.

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