JP2022108155A - battery unit - Google Patents

Abstract

To provide a battery unit which can ensure cooling efficiency of a battery cell by preventing formation of a gap between a heat dissipation sheet and the battery cell, due to expansion and contraction of the battery cell.SOLUTION: A battery unit 1 comprises: a heat dissipation sheet 30; and an insulation frame 40 which houses the heat dissipation sheet 30 in a state making contact with a cooler 20. The insulation frame 40 has: a bottom 41 having an opening 41a; and a pair of walls 42, 42 which are erected along the thickness direction from the edge of the bottom 41. The heat dissipation sheet 30 is disposed in a compressively deformed state in a housing space S, defined by the bottom 41 and the pair of walls 42, 42, in such a manner that it comes into contact with the bottom 41 and the pair of walls 42, 42 while making contact with the cooler 20 via the opening 41a. A distance D between inner wall surfaces 42a, 42a which the pair of walls 42, 42 face is smaller than a width W of a battery cell 11 perpendicular to the thickness direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a battery unit including a plurality of battery cells and a cooler for cooling them.

As the battery unit, Patent Document 1 proposes a battery unit including a plurality of battery cells, a cooler for cooling them, and a heat dissipation structure disposed between the plurality of battery cells and the cooler. It is The heat dissipating structure includes a heat-conducting sheet and is in contact with the surface of each battery cell on the cooler side and the surface of the cooler on the battery cell side.

JP 2020-47507 A

However, battery cells tend to expand and contract due to heat generation and cooling. Therefore, when the heat conductive sheet (heat radiation sheet) described in Patent Document 1 is arranged between the battery cell and the cooler, when each battery cell expands in its width direction, the heat radiation sheet follows this expansion. may extend in the width direction of the battery cell. Moreover, when each battery cell shrinks in the width direction, the heat dissipation sheet may shrink in the width direction of the battery cell following this shrinkage. When the expansion and contraction of the battery cells are repeated in this way, the heat dissipation sheet in contact with the battery cells deforms, unable to follow the expansion and contraction of the battery cells. As a result, gaps may occur between the heat dissipation sheet and the battery cells in contact therewith.

The present invention has been made in view of such points, and as the present invention, it is possible to suppress the formation of gaps between the heat dissipation sheet and the battery cells due to the expansion and contraction of the battery cells. As a result, a battery unit is provided that ensures the cooling efficiency of the battery cells.

In view of the above problems, a battery unit according to the present invention includes a plurality of battery cells, and a cooler arranged to face the plurality of battery cells and cooling the plurality of battery cells. The battery unit is arranged between the plurality of battery cells and the cooler, and includes a heat dissipating sheet having adhesiveness and being compressively deformable, and the heat dissipating sheet in contact with the cooler. and an insulating frame that accommodates a heat dissipation sheet, the plurality of battery cells are arranged in parallel in the thickness direction of the battery cells, and the insulating frame includes a bottom portion having an opening, and the bottom portion. and a pair of walls rising along the thickness direction from the edge of the heat dissipation sheet, and the heat dissipation sheet contacts the cooler through the opening in a state of being compressed and deformed. , the housing space formed by the bottom portion and the pair of wall portions so as to be in contact with the bottom portion and the pair of wall portions, and the distance between the inner wall surfaces of the pair of wall portions facing each other is smaller than the width of the battery cell perpendicular to the thickness direction.

According to the present invention, when each battery cell expands in the width direction of the battery cell due to heat generation of a plurality of battery cells, the heat dissipation sheet adhered to each battery cell follows this expansion, and the heat dissipation sheet adheres to the battery cell. Tries to stretch across the width of the cell. However, since the heat-dissipating sheet is in contact with the inner wall surfaces of the pair of walls, the wall can limit the extension of the heat-dissipating sheet following the battery cells.

Also, when each battery cell shrinks in its width direction due to cooling of the plurality of battery cells, the heat dissipation sheet adhered to each battery cell follows this shrinkage and shrinks in the width direction of the battery cell. and In the present invention, the distance between the inner wall surfaces of the pair of wall portions is smaller than the width of the battery cell. Therefore, in the present invention, the amount of shrinkage of the heat dissipation sheet is smaller than when the distance between the inner wall surfaces of the pair of wall portions is equal to or greater than the width of the battery cell. Therefore, when following the shrinkage of the battery cells from the deformed and extended state of the heat dissipation sheet, excessive shrinkage of the heat dissipation sheet can be suppressed.

Thus, in the present invention, the insulating frame restricts the extension of the heat dissipation sheet to follow the battery cells, and the contraction of the heat dissipation sheet to follow the battery cells is controlled by the distance between the inner wall surfaces of the pair of walls. can be suppressed by making the width narrower than the width of the battery cell. As a result, it is possible to suppress the formation of gaps between the heat dissipation sheet and the battery cells due to the expansion and contraction of the battery cells, thereby ensuring the cooling efficiency of the battery cells. .

1 is a schematic cross-sectional view of a battery unit according to an embodiment of the invention; FIG. FIG. 2 is a cross-sectional view of the battery unit taken along line AA of FIG. 1; FIG. 2 is a schematic perspective view of an insulating frame of the battery unit shown in FIG. 1; 7 is a graph for explaining an example of change in repulsive force of a heat dissipation sheet over time; 3(a) is a diagram for explaining a state in which an insulating frame restricts the elongation of a heat dissipation sheet in the battery unit shown in FIG. It is a figure explaining the state which tracks and shrinks. FIG. 3 is a schematic conceptual diagram illustrating a method of assembling the battery unit shown in FIG. 2; 3 is a cross-sectional view according to a modification of the battery unit corresponding to FIG. 2; FIG.

An embodiment and modifications thereof according to the present invention will be described below with reference to FIGS. 1 to 7. FIG.

The battery unit 1 of this embodiment is mounted in a vehicle such as a hybrid vehicle and an electric vehicle. As shown in FIGS. 1 and 2, the battery unit 1 of this embodiment includes a battery module 10, a cooler 20, a heat dissipation sheet 30, and an insulating frame 40. As shown in FIGS.

As shown in FIG. 2, the battery module 10 includes a plurality of battery cells 11, 11, . . . , and each battery cell 11 has a rectangular solid shape. are arranged side by side in the thickness direction H of the battery cell 11 . In the embodiment shown in FIG. 1, seven battery cells 11 are arranged side by side in the thickness direction H, but the number of battery cells 11 is not limited to this. Adjacent battery cells 11, 11 are connected, and battery cells 11, 11 at both ends of the plurality of battery cells 11, 11 . . . may be sandwiched between a pair of end plates (not shown).

The battery cell 11 is a secondary battery configured by accommodating a negative electrode material, a positive electrode material, a separator, and the like in a rectangular parallelepiped case. Examples of secondary batteries include lithium ion batteries. Positive and negative terminals 12, 12 are provided on the upper part of the battery cell 11, and the plurality of battery cells 11, 11, . . . are electrically connected by a bus bar (not shown).

The cooler 20 is arranged to face the plurality of battery cells 11, 11 . . . and cools the plurality of battery cells 11, 11 . The cooler 20 is block-shaped and made of metal such as aluminum. Inside the cooler 20, a refrigerant passage 21 is formed through which a cooling solvent R that exchanges heat with the plurality of battery cells 11, 11 . . . cooling solvent) flows through the coolant passage 21 . In the present embodiment, the surface of the cooler 20 on the battery cell 11 side serves as a cooling surface 20a for cooling the battery cell 11 via the heat radiation sheet 30 .

The heat dissipation sheet 30 is arranged between the bottom surfaces 11a, 11a, . . . of the plurality of battery cells 11, 11 . In this embodiment, the heat dissipation sheet 30 is arranged in a state of being compressed and deformed in the thickness direction of the heat dissipation sheet 30 between the plurality of battery cells 11, 11 (battery modules 10) and the cooler 20. .

Specifically, the heat-dissipating sheet 30 is compressed and deformed in the thickness direction of the heat-dissipating sheet 30 by the load from the battery cells 11 , and the cooling surface 20 a of the cooler 20 is pushed through the opening 41 a of the insulating frame 40 . are in contact with In this embodiment, the heat dissipation sheet 30 is compressively deformable. As will be described later, the heat-dissipating sheet 30 is compressed and deformed by the load from the battery cells 11 so that the bottom surface 11 a of each battery cell 11 , the bottom portion 41 of the insulating frame 40 , and the pair of wall portions 42 are arranged. , 42 in a housing space S of an insulating frame 40 formed by a bottom portion 41 and a pair of wall portions 42 , 42 .

The heat dissipation sheet 30 has thermal conductivity necessary for efficiently dissipating the heat of the battery cells 11 to the cooler 20 . The thermal conductivity of the heat dissipation sheet 30 is preferably 0.8 W/m·K or more as measured by the hot disk method. Moreover, the heat dissipation sheet 30 is made of a material that has flexibility and can be freely deformed by compression. The hardness of the heat dissipation sheet 30 is preferably 0 or more as measured by a durometer (Asker C). Furthermore, the heat dissipation sheet 30 has adhesiveness. The adhesiveness of the heat dissipation sheet 30 is not particularly limited as long as the heat dissipation sheet 30 can stick to the bottom surface 11a of the battery cell 11 .

The material of the heat-dissipating sheet 30 is not particularly limited as long as it has adhesiveness on the surface of the heat-dissipating sheet 30 and can be deformed (compressively deformed) by a compressive load. , room-temperature-curing, moisture-curing, or ultraviolet-curing thermosetting resins. As the material of the heat dissipation sheet 30, a one-liquid type or two-liquid mixed type thermosetting resin may be used. Examples of such thermosetting resins include silicone resins, epoxy resins, and urethane resins. Furthermore, the heat dissipation sheet 30 may contain a filler in order to improve thermal conductivity, and an insulating inorganic compound may be used as the filler.

The heat-dissipating sheet 30 is not limited to a single structure, and may be formed by forming a thermally conductive adhesive layer on the surface of the main body of the heat-dissipating sheet. The adhesive layer may be formed on both sides of the heat-dissipating sheet main body, or may be formed on either side. When an adhesive layer is formed on one of the surfaces of the heat dissipation sheet main body, it is preferable to adhere the surface on which the adhesive layer is formed to the bottom surface 11 a of the battery cell 11 .

In the present embodiment, a commercially available product may be used for the heat dissipation sheet 30. For example, a heat dissipation silicone rubber sheet (Shin-Etsu Chemical Co.: TC-200CAT-20) or Cool Provided (registered trademark) (Kitagawa Industries: CPVP ) and the like.

The insulating frame 40 is provided between the heat dissipation sheet 30 and the cooler 20 . As shown in FIG. 3, the insulating frame 40 has a bottom portion 41 having an opening 41a and a pair of wall portions 42, 42 rising from the edge portions of the bottom portion 41 along the thickness direction H. there is The insulating frame 40 has a bottom portion 41 and a pair of wall portions 42 , 42 forming an accommodation space S that accommodates part of the heat dissipation sheet 30 . The bottom portion 41 of the insulating frame 40 is in contact with the cooler 20, and the heat radiation sheet 30 accommodated in the accommodation space S in a state of being compressed and deformed touches the cooling surface 20a of the cooler 20 through the opening 41a. in contact.

In the insulating frame 40, as shown in FIG. 2, the distance D between the inner wall surfaces 42a, 42a of the pair of wall portions 42, 42 facing each other is smaller than the width W of (the bottom surface 11a of) the battery cell 11. As shown in FIG. The width W of the bottom surface 11a of the battery cell 11 is the length in the direction orthogonal to the thickness direction H. As shown in FIG.

As the material of the insulating frame 40, a thermoplastic resin having insulating properties may be used. Examples of thermoplastic resins include polypropylene resins, polybutylene terephthalate resins, polyamide resins, polyphenylene sulfide resins, and the like. The insulating frame 40 is preferably molded by injection molding.

According to the battery unit 1, the heat generated during charging and discharging of the plurality of battery cells 11, 11 . . . It is conducted to the cooling surface 20a of the cooler in close contact. The heat conducted to the cooling surface 20 a is absorbed by the cooling solvent R flowing inside the cooler 20 . As a result, the plurality of battery cells 11, 11... can be cooled.

By the way, when the battery cell 11 generates heat, the battery cell 11 expands, and when the expanded battery cell 11 is cooled (is allowed to cool), the battery cell 11 contracts. Due to the expansion and contraction of the battery cell 11 , a gap may be formed between the heat dissipation sheet 30 and the bottom surface 11 a of the battery cell 11 . Therefore, in this embodiment, the insulating frame 40 is provided to suppress the formation of this gap. Details are given below.

FIG. 4 is a graph for explaining an example of changes in the repulsive force of the heat dissipation sheet over time. A solid line L1 shown in FIG. 4 is the waveform of the repulsive force over time when a constant load is applied to the heat dissipation sheet 30 accommodated in the insulating frame 40 in the battery unit of this embodiment. A dashed line L2 shown in FIG. 4 is the waveform of the repulsive force over time when a constant load is applied to the heat dissipation sheet 30 without the heat dissipation sheet 30 being accommodated in the insulating frame 40 . The constant load applied to the heat dissipation sheet 30 is the load applied from the bottom surface of the battery module 10 . A period A shown in FIG. 4 corresponds to a period during which the battery module 10, the heat dissipation sheet 30, the insulating frame 40, and the cooler 20 are assembled while the heat dissipation sheet 30 is compressed. equivalent to the period during which the

As is clear from the dashed line L2, when the insulating frame 40 is not used and the heat dissipation sheet 30 is compressed in the thickness direction by the battery cell 11, the heat dissipation sheet 30 gradually expands in the width direction of the battery cell 11. growing. When the expansion and contraction of the battery cells 11 are repeated, such deformation is repeated, and the heat dissipation sheet 30 is likely to suffer from settling (creep deformation). The sagging heat dissipation sheet 30 has a smaller thickness than the heat dissipation sheet 30 at the time of assembly, and extends in the width direction of the bottom surface 11a of the battery cell.

As a result, as shown by the dashed line L2, when the heat dissipation sheet 30 is not accommodated in the insulating frame 40 (the insulating frame 40 is not provided in the battery unit 1), the repulsive force (restoring force ) decreases. Therefore, when the repulsive force is reduced, even if the battery cell 11 expands, the contraction of the heat dissipation sheet 30 is difficult to follow. Therefore, heat conduction through the heat dissipation sheet 30 is reduced.

On the other hand, when the heat dissipation sheet 30 is accommodated in the insulating frame 40 as in the present embodiment, the heat dissipation sheet 30 is in contact with the inner wall surfaces 42a, 42a of the pair of wall portions 42, 42 of the insulating frame 40. . Accordingly, as described above, even if the heat dissipation sheet 30 is compressed, it is possible to prevent the heat dissipation sheet 30 from extending in the width direction of the battery cell 11 . Therefore, even if the heat-dissipating sheet 30 is repeatedly compressed and contracted, the heat-dissipating sheet 30 is unlikely to become permanent.

As a result, as indicated by the solid line L1, when the heat dissipation sheet 30 is accommodated in the insulating frame 40, the repulsive force of the heat dissipation sheet 30 is less likely to decrease over time during the period B. Therefore, even when the battery cell 11 expands and then contracts, the repulsive force of the heat-dissipating sheet 30 is stably maintained, so that a gap is formed between the heat-dissipating sheet 30 and the bottom surface 11a of the battery cell 11. can be suppressed, and the cooling efficiency of the battery cells 11 can be ensured.

Next, operation of the battery unit 1 according to the present embodiment will be described with reference to FIGS. 5(a) and 5(b). FIG. 5(a) is a diagram for explaining a state in which the insulating frame 40 restricts the expansion of the heat dissipation sheet 30 in the battery unit 1 shown in FIG. 2, and FIG. 1 is a diagram illustrating a state in which the heat dissipation sheet 30 shrinks following the battery cell 11 in FIG.

As shown in FIG. 5( a ), when the battery cell 11 expands in its width direction, the heat dissipation sheet 30 adhered to the bottom surface 11 a of the battery cell 11 follows this expansion and moves in the width direction of the battery cell 11 . try to grow. However, since the heat dissipation sheet 30 is in contact with the inner wall surfaces 42a, 42a of the pair of wall portions 42, 42, the pair of wall portions 42, 42 restricts the expansion of the heat dissipation sheet 30 following the battery cells 11. be able to.

Further, as shown in FIG. 5B, when the battery cell 11 shrinks in its width direction, the heat dissipation sheet 30 adhered to the bottom surface 11a of the battery cell 11 follows this shrinkage and spreads across the width of the battery cell 11. to shrink in the direction In this embodiment, the distance D between the inner wall surfaces of the pair of wall portions 42 , 42 is smaller than the width W of the bottom surface 11 a of the battery cell 11 . Therefore, compared to the case where the distance D between the inner wall surfaces of the pair of wall portions 42 and 42 is equal to or greater than the width W of the battery cell 11, the heat dissipation sheet 30 of this embodiment shrinks less. Therefore, when following the contraction of the battery cell from the deformed and extended state of the heat dissipation sheet 30, excessive contraction of the heat dissipation sheet 30 (see the dashed arrow in FIG. 5B) can be suppressed.

In this manner, the insulating frame 40 restricts the expansion of the heat dissipation sheet 30 to follow the battery cells 11 , and the contraction of the heat dissipation sheet 30 to follow the battery cells 11 is controlled by the pair of wall portions 42 , 42 . This can be suppressed by making the distance D between the wall surfaces narrower than the width W of the battery cell 11 . As a result, it is possible to suppress the formation of gaps between the heat dissipation sheet 30 and the bottom surface 11a of the battery cell 11 due to the expansion and contraction of the battery cell 11 in the width direction. 11 cooling efficiency can be ensured.

A method for assembling the battery unit 1 of the present embodiment will be described with reference to FIG. First, the battery module 10, the heat dissipation sheet 30, the insulating frame 40, and the cooler 20 are prepared. A plurality of battery cells 11 are arranged side by side in the thickness direction H in the prepared battery module 10 (see FIG. 1). The size of the heat dissipation sheet 30 is such that the heat dissipation sheet 30 is compressed and deformed by a load applied by the battery module 10 (to be described later), and is deformed so as to expand in the width direction of the battery cell 11 . It has a size that allows contact with the inner wall surfaces 42a, 42a. Further, the height h of the wall portion 42 of the prepared insulating frame 40 is adjusted so that the pair of wall portions 42, 42 do not come into contact with the bottom surface 11a of the battery cell 11 during assembly. 50% or less of the thickness t of the heat radiation sheet 30).

Next, the prepared battery module 10, heat dissipation sheet 30, insulating frame 40, and cooler 20 are assembled. Specifically, after the insulating frame 40 is arranged at a predetermined position on the cooling surface 20a of the cooler 20, the heat dissipation sheet 30 is arranged on the surface of the bottom portion 41 of the insulating frame 40 so as to cover the opening 41a. do. Next, the battery module 10 is brought into contact with the heat dissipation sheet 30 , and the heat dissipation sheet 30 is pressed by the battery module 10 to compress the heat dissipation sheet 30 in the thickness direction of the heat dissipation sheet 30 .

As a result, the prepared heat dissipation sheet 30 is stretched and deformed toward the pair of wall portions 42 , 42 , and the deformed heat dissipation sheet 30 is applied to the bottom surface 11 a of each battery cell 11 , each inner wall surface 42 a , and the bottom portion 41 . As well as contacting the surface, it is possible to contact the cooling surface 20a of the cooler 20 via the opening 41a (see FIGS. 1 and 2). Moreover, the insulating frame 40 is fixed on the cooling surface 20 a of the cooler 20 by being sandwiched between the heat radiating sheet 30 and the cooler 20 in a state of being compressed and deformed.

Next, with the heat dissipation sheet 30 being compressed, the fixing portion (not shown) of the battery module 10 and the fixing portion (not shown) of the cooler 20 are fastened together using bolts and nuts (not shown). . As a result, part of the heat-dissipating sheet 30 is housed in the insulating frame 40, the bottom surface 11a of each battery cell 11 and the heat-dissipating sheet 30 are in close contact, and the cooling surface 20a of the cooler 20 and the heat-dissipating sheet 30 are in close contact. The battery unit 1 in the state can be manufactured.

<Modified example of the present embodiment>
A modification of this embodiment will be described with reference to FIG. FIG. 7 is a cross-sectional view according to a modification of the battery unit 1 shown in FIG. As shown in FIG. 7, this modification differs from the above-described embodiment in that a convex portion 43 is formed on the bottom portion 41 of the insulating frame 40, and a concave portion into which the convex portion 43 is inserted into the cooling surface 20a of the cooler 20. 22 is formed. Therefore, the differences will be described below, and the same reference numerals will be given to the same members and parts as in the above-described embodiment, and detailed description thereof will be omitted.

In this modification, a pair of projections 43, 43 are formed on the bottom portion 41 of the insulating frame 40 with an opening 41a interposed therebetween. Each projection 43 protrudes toward the cooling surface 20 a of the cooler 20 . With the insulating frame 40 in contact with the cooling surface 20 a of the cooler 20 , the projections 43 are engaged with the recesses 22 formed on the cooling surface 20 a of the cooler 20 .

The convex portion 43 may be a convex strip extending along the thickness direction H of the battery cell 11, in which case the concave portion 22 becomes a concave groove. The convex portion 43 and the concave portion 22 may be formed continuously along the thickness direction H, or may be formed intermittently.

In this modified example, protrusions 43 are provided on both sides of the insulating frame 40 across the opening 41a. 11 width direction), and the heat dissipation sheet 30 can be constrained by the insulating frame 40 . In the method for assembling the battery unit 1 of this modified example, when the insulating frame 40 is arranged on the cooling surface 20a of the cooler, the convex portion 43 is fitted into the concave portion 22, so that the insulating frame 40 can be easily aligned.

An embodiment of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention described in the scope of claims. Design changes can be made.

1: battery unit, 11: battery cell, 20: cooler, 30: heat dissipation sheet, 40: insulating frame, 41: bottom, 41a: opening, 42: wall, 42a: inner wall surface, D: between inner wall surfaces Distance, H: thickness direction, S: storage space, W: width of battery cell

Claims (1)

a plurality of battery cells;
A battery unit comprising: a cooler arranged to face the plurality of battery cells and cooling the plurality of battery cells,
The battery unit is arranged between the plurality of battery cells and the cooler, and has adhesiveness and a heat dissipation sheet that is compressively deformable;
an insulating frame that accommodates the heat dissipation sheet in contact with the cooler,
The plurality of battery cells are arranged side by side in the thickness direction of the battery cells,
The insulating frame has a bottom portion having an opening and a pair of wall portions rising along the thickness direction from the edge portion of the bottom portion,
The heat dissipation sheet, in a state of being compressed and deformed, contacts the cooler through the opening, and also contacts the bottom and the pair of walls so as to contact the bottom and the pair of walls. It is placed in a storage space formed by
A battery unit, wherein a distance between opposing inner wall surfaces of the pair of wall portions is smaller than a width of the battery cell perpendicular to the thickness direction.

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