JP2014157763A - Method for manufacturing heat transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce reaction force of a heat transfer sheet held between a power storage module and a cooling plate.SOLUTION: In a first step, a heat transfer sheet 21 which comprises a pressure receiving surface 21a that contacts a cooling plate 12 or a power storage plate 13 and a free surface 21b which is perpendicular to the pressure receiving surface 21a and surrounds the periphery of the pressure receiving surface 21a is manufactured. In a second step, the required reaction force of the heat transfer sheet 21 is decided. In a third step, the reaction force produced by the heat transfer sheet 21 is reduced lower than the required reaction force by reducing the ratio (shape factor S) of the area A of the pressure receiving surface 21a to the area F of the free surface 21b by cutting the heat transfer sheet 21 into a plurality of pieces. Therefore, damage to the power storage module 13 and its fixing section due to the reaction force from the heat transfer sheet 21 can be prevented.

Description

  The present invention relates to a heat transfer sheet manufacturing method for manufacturing a heat transfer sheet sandwiched between a cooling plate and a power storage module.

  Between the cooling surface of the power storage module (assembled battery) in which a plurality of power storage cells (square batteries) and a plurality of holders (separators) are alternately stacked, and the cooling plate through which the refrigerant flows, have elasticity and thermal conductivity In addition, the heat transfer sheet (heat conductive sheet) excellent in electrical insulation is sandwiched, and the heat transfer sheet is elastically deformed so that the cooling surface of the power storage module and the cooling plate are brought into close contact with each other. Patent Document 1 listed below discloses that the cooling performance is improved by efficiently transmitting to the surface.

JP 2011-34775 A

  By the way, since the power storage module is fixed to the cooling plate in a state where the heat transfer sheet is compressed and elastically deformed, the reaction force of the compressed heat transfer sheet is applied to the power storage module and the cooling plate to configure the power storage module. There is a possibility that the storage cell to be damaged may be damaged, or the fixing portion for fixing the storage module to the cooling plate may be damaged. In order to prevent this, it is desirable to reduce the reaction force of the heat transfer sheet as much as possible.

  This invention is made | formed in view of the above-mentioned situation, and it aims at reducing the reaction force of the heat-transfer sheet clamped between an electrical storage module and a cooling plate.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a heat transfer sheet manufacturing method for manufacturing a heat transfer sheet sandwiched between a cooling plate and a power storage module, wherein the cooling A first step of manufacturing the heat transfer sheet comprising a pressure receiving surface in contact with the plate or the power storage module and a free surface that is orthogonal to the pressure receiving surface and surrounds the periphery of the pressure receiving surface; The reaction force generated by the heat transfer sheet is reduced below the required reaction force by reducing the ratio of the area of the pressure receiving surface to the area of the free surface of the heat transfer sheet and the second step of determining the force. The manufacturing method of the heat-transfer sheet | seat characterized by including a 3rd process is proposed.

  According to the invention described in claim 2, in addition to the configuration of claim 1, a method of manufacturing a heat transfer sheet is proposed in which the heat transfer sheet is cut into a plurality of pieces in the third step. The

  According to the invention described in claim 3, in addition to the structure of claim 1 or 2, the free surface of the heat transfer sheet is formed in a corrugated shape in the third step. A sheet manufacturing method is proposed.

  According to the invention described in claim 4, in addition to the configuration of claim 3, the heat transfer sheet is sliced in a direction orthogonal to the thickness direction and divided into a plurality of divided pieces, and the division is performed. A method of manufacturing a heat transfer sheet is proposed, in which the ends of the pieces are alternately cut into different shapes, and then the divided pieces are laminated again to form a free surface of the heat transfer sheet in a waveform. The

  According to a fifth aspect of the present invention, there is provided a heat transfer sheet manufacturing method for manufacturing a heat transfer sheet sandwiched between a cooling plate and a power storage module, wherein the heat transfer sheet is in contact with the cooling plate or the power storage module. A first step of manufacturing the heat transfer sheet comprising a pressure receiving surface and a free surface surrounding the pressure receiving surface perpendicular to the pressure receiving surface, and a second step of determining a required reaction force of the heat transfer sheet And a third step of reducing the shape factor of the heat transfer sheet so that the reaction force of the heat transfer sheet is less than or equal to the required reaction force, and the shape factor determines the area of the pressure receiving surface of the free surface A method of manufacturing a heat transfer sheet, characterized by being divided by the area, is proposed.

  The battery module 13 of the embodiment corresponds to the power storage module of the present invention.

  According to the configuration of claim 1, a heat transfer sheet including a pressure receiving surface that contacts the cooling plate or the power storage module in the first step and a free surface that is orthogonal to the pressure receiving surface and surrounds the periphery of the pressure receiving surface is manufactured. The required reaction force of the heat transfer sheet is determined in the second step, and the ratio of the pressure receiving surface area to the free surface area of the heat transfer sheet is reduced in the third step, thereby requesting the reaction force generated by the heat transfer sheet. Since it reduces to below reaction force, it can prevent beforehand that a power storage module and its fixing | fixed part are damaged with the reaction force which it receives from a heat-transfer sheet | seat.

  According to the configuration of claim 2, since the heat transfer sheet is cut into a plurality of parts in the third step, the ratio of the area of the pressure receiving surface to the area of the free surface of the heat transfer sheet can be reduced.

  According to the configuration of the third aspect, since the free surface of the heat transfer sheet is formed in a waveform in the third step, the ratio of the area of the pressure receiving surface to the area of the free surface of the heat transfer sheet can be reduced.

  According to the configuration of claim 4, the heat transfer sheet is sliced in a direction orthogonal to the thickness direction and divided into a plurality of divided pieces, and the ends of the divided pieces are alternately cut into different shapes, By laminating the divided pieces again, the free surface of the heat transfer sheet is formed into a corrugated shape, so that a deep corrugated shape can be easily formed.

  According to the fifth aspect of the present invention, a heat transfer sheet comprising a pressure receiving surface that contacts the cooling plate or the power storage module in the first step and a free surface that is orthogonal to the pressure receiving surface and surrounds the periphery of the pressure receiving surface is manufactured. The required reaction force of the heat transfer sheet is determined in the second step, and the shape factor of the heat transfer sheet is reduced so that the reaction force of the heat transfer sheet is equal to or less than the required reaction force in the third step. Since the shape factor is obtained by dividing the area of the pressure receiving surface by the area of the free surface, the power storage module and the cooling plate can be prevented from being damaged by the reaction force received from the heat transfer sheet.

The perspective view of a battery module. The exploded perspective view of a battery module. The figure which shows the shape of a heat-transfer sheet | seat. (Comparative example and first and second embodiments) Explanatory drawing of the pressure receiving area and free area of a heat-transfer sheet | seat. The figure which shows the shape of a heat-transfer sheet | seat. (Third embodiment) The figure which shows the shape of a heat-transfer sheet | seat. (Fourth embodiment) Explanatory drawing of the manufacturing method of a heat-transfer sheet | seat. (Fourth embodiment)

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the battery pack 11 mounted on the electric vehicle is configured by supporting a plurality of battery modules 13 on a cooling plate 12, and FIG. 1 and FIG. A part of the plate 12 and two battery modules 13, 13 are shown. In the present embodiment, the two battery modules 13 are integrated, but the structure of each battery module 13 is substantially the same.

  The battery module 13 is formed by laminating a plurality of (12 in the embodiment) lithium ion batteries each of which is a rectangular parallelepiped with a synthetic resin intermediate holder 15 interposed therebetween, and at both ends in the stacking direction. Synthetic resin end holders 16 and 16 are stacked on the outside of the two battery cells 14 and 14 positioned, respectively.

  A pair of end plates 17, 17 are superimposed on the stacking direction outer surfaces of the pair of end holders 16, 16 of each battery module 13, and the pair of end plates 17, 17 are fastened by a fastening band 18, thereby The battery cells 14, the eleven intermediate holders 15, and the two end holders 16, 16 are firmly integrated. The two fastening bands 18 and 18 are shared by the two battery modules 13 and 13. The contact surfaces of the battery cells 14, the intermediate holders 15, and the end holders 16, 16 are fixed with an adhesive.

  A bus bar plate 19 holding a plurality of bus bars (not shown) is fixed on the upper surface of the battery module 13, and the terminals of the battery cells 14 are electrically connected by the bus bar plate 19. Then, the upper surfaces of the two battery modules 13 and 13 arranged side by side are covered with a common synthetic resin cover 20.

  The lower surfaces of the twelve battery cells 14 constituting the battery module 13, that is, the lower surfaces of the battery modules 13 constitute a cooling surface facing the upper surface of the cooling plate 12. A rectangular heat transfer sheet 21 is sandwiched between the upper surface of the sheet. The material of the heat transfer sheet 21 is a synthetic resin (for example, silicone rubber) excellent in thermal conductivity, and can be crushed and deformed into an arbitrary shape when pressure is applied.

  An insulating sheet 22 is disposed between the lower surface of the heat transfer sheet 21 and the upper surface of the cooling plate 12. The insulating sheet 22 is made of a synthetic resin such as PP (polypropylene) or PPS (polyphenylene sulfide) having non-conductivity and water repellency and is formed in a shallow tray shape, and a lower portion of the battery module 13 is fitted therein. . Therefore, the upper surface of the heat transfer sheet 21 comes into contact with the cooling surface of the battery cells 14, and the lower surface of the heat transfer sheet 21 comes into contact with the upper surface of the insulating sheet 22. Since the thickness of the insulating sheet 22 is extremely thin, it hardly interferes with heat transfer.

  The cooling plate 12 is a metal hollow member excellent in thermal conductivity, and a refrigerant passage 12c through which a refrigerant (for example, cooling air) flows is defined between the upper wall portion 12a and the lower wall portion 12b. Cooling air sucked by a cooling fan (not shown) flows in the refrigerant passage 12c of the cooling plate 12, and is transmitted from the cooling surface of the battery cell 14 to the upper wall portion 12a via the heat transfer sheet 21 and the insulating sheet 22. The battery cells 14 are cooled by the heat exchange between the generated heat and the cooling air.

  The battery module 13 to which the heat transfer sheet 21 and the insulating sheet 22 are attached on the lower surface is placed on the upper wall portion 12a of the cooling plate 12, and the cooling plate with bolts 23 passing through the mounting flanges 17a of the end plates 17, 17. It is fixed to 12 mounting bosses 12d. At that time, the heat transfer sheet 21 against which the battery module 13 is pressed is compressed in the vertical direction and crushed, and the clearance between the upper surface of the heat transfer sheet 21 and the cooling surface of the battery module 13 and the lower surface of the heat transfer sheet 21 are reduced. And the clearance gap between the upper wall parts 12a of the cooling plate 12 disappears, and the heat transfer from the battery module 13 to the cooling plate 12 is efficiently performed, so that the cooling performance of the battery module 13 is improved.

  Although the insulating sheet 22 is interposed between the lower surface of the heat transfer sheet 21 and the upper wall portion 12a of the cooling plate 12, the insulating sheet 22 is made of an extremely thin synthetic resin and can be easily deformed. The interposition of the insulating sheet 22 does not generate a gap that prevents heat transfer.

  Next, a method for manufacturing the heat transfer sheet 21 will be described with reference to FIG.

  FIG. 3A shows a comparative example (conventional example) of the heat transfer sheet 21, which is cut into a rectangular shape having substantially the same dimensions as the cooling surface of the battery module 13. In the embodiment, the heat transfer sheet 21 has a thickness of 3 mm, a long side of 400 mm, and a short side of 100 mm, which overlaps the upper surface of the insulating sheet 22. When the entire cooling surface of the battery module 13 overlaps the heat transfer sheet 21 as in the comparative example, the heat transfer sheet 21 is compressed by being sandwiched between the cooling surface of the battery module 13 and the upper wall portion 12a of the cooling plate 12. The reaction force of the battery module 13 may be excessive, and the battery cells 14 constituting the battery module 13 and the mounting flanges 17a of the end plates 17 and 17 for fixing the battery module 13 to the cooling plate 12 may be damaged.

  In the first embodiment shown in FIG. 3B, a 400 mm × 70 mm heat transfer sheet material 21 ′ in which the short side of the heat transfer sheet 21 of the comparative example is reduced from 100 mm to 70 mm by injection molding is manufactured. By cutting the heat transfer sheet material 21 ′ in the direction along the long side, five heat transfer sheets 21 of 400 mm × 14 mm are manufactured, and the five heat transfer sheets 21. It arrange | positions at equal intervals on the space of 400 mm x 100 mm of the same magnitude | size as the sheet | seat 21. FIG. As a result, the cooling surface of the battery module 13 comes into contact with the five heat transfer sheets 21 arranged at equal intervals.

  In the second embodiment shown in FIG. 3C, a heat transfer sheet material 21 ′ of 250 mm × 100 mm in which the long side of the heat transfer sheet 21 of the comparative example is reduced from 400 mm to 250 mm by injection molding is manufactured. By cutting the heat transfer sheet material 21 ′ in the direction along the short side, 12 heat transfer sheets 21 of 20.8 mm × 100 mm are manufactured, and the 12 heat transfer sheets 21 of the comparative example are manufactured. It arrange | positions at equal intervals on the space of 400 mm x 100 mm of the same magnitude | size as the heat-transfer sheet | seat 21. FIG. As a result, the cooling surface of the battery module 13 comes into contact with twelve heat transfer sheets 21 arranged at equal intervals.

  FIG. 4 shows one heat transfer sheet 21 having a long side of A, a short side of B, and a thickness of T, and the upper surface and the lower surface thereof constitute a pressure receiving surface 21a, respectively, and the four sides of the pressure receiving surface 21a. Four side surfaces in contact with each other constitute a free surface 21b. The area M of the pressure receiving surface 21a corresponds to the area of the upper surface or the lower surface of the heat transfer sheet 21, and is given by M = A × B. The area F of the free surface 21b corresponds to the sum of the areas of the four side surfaces, and is given by F = 2 × T × (A + B). The shape factor S is defined by S = M / F, and is a parameter representing the magnitude of the reaction force generated by the compressed heat transfer sheet 21. That is, the larger the shape factor S, the larger the reaction force when the heat transfer sheet 21 is compressed, and the smaller the shape factor S, the smaller the reaction force when the heat transfer sheet 21 is compressed. In the present embodiment, the shape factor S, that is, the reaction force is reduced by cutting the heat transfer sheet 21 and dividing it into a plurality of small heat transfer sheets 21.

As is evident from Table 1, the area M of the pressure receiving surface 21a of the comparative example 40000 mm ^2, the area F of the free surface 21b is 3000 mm ^2, the shape factor S is 13.3. On the other hand, the sum of the areas M of the pressure receiving surfaces 21a of the five heat transfer sheets 21 in the first embodiment is 28000 mm ² , and the sum of the areas F of the free surfaces 21b of the five heat transfer sheets 21 is 12400 mm ^2. The shape factor S is 2.3, which indicates that the shape factor S is significantly reduced as compared with the comparative example. The total area F of the second total sum of the areas M of 12 sheets of the heat transfer sheet 21 ... pressure-receiving surface 21a of the embodiment 25000 mm ^2, 12 sheets of the heat transfer sheet 21 ... free surface 21b of 8700Mm ^2, The shape factor S was 2.9, which indicates that the shape factor S was significantly reduced compared to the comparative example.

  The method of dividing the heat transfer sheet 21 is determined as follows. That is, an allowable upper limit value (required reaction force) of the reaction force generated by the heat transfer sheet 21 is obtained from the strength of the battery cells 14 and the strength of the fixing portion of the battery module 13 with respect to the cooling plate 12. As shown in Table 1, since the heat transfer sheet 21 of the comparative example having the shape factor S of 13.3 is experimentally known to have an actual reaction force of 10 kN, for example, if the required reaction force is 3 kN. For example, the shape factor S satisfying the required reaction force can be calculated, and the heat transfer sheet 21 may be divided into appropriate shapes so as to satisfy the shape factor S.

  Since the heat transfer sheets 21 of the first and second embodiments are divided into a plurality of parts, there is a problem that the work of arranging them at predetermined intervals becomes troublesome. The third embodiment shown in FIG. 5 is an improvement of the first embodiment and is intended to improve the handleability of the heat transfer sheet 21. That is, the heat transfer sheet 21 according to the third embodiment is divided into five parts of the heat transfer sheet 21 having a thickness of 3 mm, leaving a portion with a thickness of 0.5 mm, and the five parts are substantially divided. The five parts having a thickness of 2.5 mm are integrally connected by the connection part having a thickness of 0.5 mm, thereby preventing the parts from being separated and improving the handleability.

  In addition, the recessed part of the heat-transfer sheet | seat 21 which concerns on 3rd Embodiment can be formed by scraping off a part of the surface with a tooth implement.

  As shown in Table 1, since the thickness T of the portion divided into five parts is reduced from 3 mm to 2.5 mm in the first embodiment, the area F of the free surface 21b is the same as that in the first embodiment. It decreases to 5/6, and the shape factor S increases accordingly.

  The fourth embodiment shown in FIG. 6 increases the area F of the free surface 21b and decreases the shape factor S without changing the thickness T of the heat transfer sheet 21. Therefore, in the fourth embodiment, the four free surfaces 21b of the heat transfer sheet 21 are bent in a waveform, and for example, the surface area is 1.5 times that of a flat surface (equivalent to a thickness T = 4.5 mm). ) By increasing, the shape factor S is reduced to 2/3.

  In addition, in order to process the free surface 21b of the heat transfer sheet 21 into a corrugated shape, it may be scraped off with a tooth tool as in the third embodiment. As another method, as shown in FIG. 7, the heat transfer sheet 21 is sliced in a direction orthogonal to the thickness direction and divided into a plurality of divided pieces 21 ′, and the ends of the divided pieces 21 ′. After the portions are alternately cut into different shapes, the divided pieces 21 'may be laminated again. At this time, the divided pieces 21 'may be bonded together. By this manufacturing method, it is possible to easily form a deep waveform that is difficult to process by cutting.

  As described above, according to the present embodiment, the heat transfer sheet 21 is cut into a plurality of parts to increase the aspect ratio (the ratio of A to B), or the long side length A and the short side length B. The ratio of the area M of the pressure receiving surface 21a to the area F of the free surface 21b is increased by increasing the ratio of the thickness T to the surface or by bending the free surface 21b into a waveform to increase the substantial thickness T. Since the certain shape factor S is reduced, the reaction force of the heat transfer sheet 21 can be reduced to prevent the battery cells 14 and the battery module 13 from being damaged.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the battery module 13 according to the embodiment is not limited to one configured with a lithium ion battery, and may be configured with another type of battery or capacitor.

  In addition, the power storage module of the present invention is not limited to one constituted by a single battery module 13, and may be constituted by a plurality of battery modules 13.

  In the embodiment, the insulating sheet 22 is disposed between the heat transfer sheet 21 and the cooling plate 12, but the insulating sheet 22 may be omitted.

  In the third and fourth embodiments, after the heat transfer sheet 21 having a simple rectangular cross section is manufactured, the cross section is processed so as to have a target shape. From the above, injection molding may be performed with a mold so as to obtain a desired cross-sectional shape.

12 Cooling plate 13 Battery module (storage module)
21 Heat transfer sheet 21a Pressure receiving surface 21b Free surface 21 'Split piece F Free surface area M Pressure receiving surface area S Shape factor

Claims (5)

A heat transfer sheet manufacturing method for manufacturing a heat transfer sheet (21) sandwiched between a cooling plate (12) and a power storage module (13),
A pressure receiving surface (21a) that contacts the cooling plate (12) or the power storage module (13), and a free surface (21b) that is orthogonal to the pressure receiving surface (21a) and surrounds the periphery of the pressure receiving surface (21a). A first step of producing the heat transfer sheet (21),
A second step of determining a required reaction force of the heat transfer sheet (21);
The reaction force generated by the heat transfer sheet (21) by reducing the ratio of the area (M) of the pressure receiving surface (21a) to the area (F) of the free surface (21b) of the heat transfer sheet (21). Including a third step of reducing the reaction force below the required reaction force.   The method for manufacturing a heat transfer sheet according to claim 1, wherein the heat transfer sheet (21) is cut into a plurality of pieces in the third step.   The method of manufacturing a heat transfer sheet according to claim 1 or 2, wherein the free surface (21b) of the heat transfer sheet (21) is formed in a corrugated shape in the third step.   The heat transfer sheet (21) is sliced in a direction perpendicular to the thickness direction and divided into a plurality of divided pieces (21 '), and the ends of the divided pieces (21') are cut alternately into different shapes. After that, the heat transfer sheet according to claim 3, wherein the divided surface (21 ') is laminated again to form a free surface (21b) of the heat transfer sheet (21) into a corrugated shape. Manufacturing method. A heat transfer sheet manufacturing method for manufacturing a heat transfer sheet (21) sandwiched between a cooling plate (12) and a power storage module (13),
A pressure receiving surface (21a) that contacts the cooling plate (12) or the power storage module (13), and a free surface (21b) that is orthogonal to the pressure receiving surface (21a) and surrounds the periphery of the pressure receiving surface (21a). A first step of producing the heat transfer sheet (21),
A second step of determining a required reaction force of the heat transfer sheet (21);
A third step of reducing the shape factor (S) of the heat transfer sheet (21) so that the reaction force of the heat transfer sheet (21) is less than or equal to the required reaction force,
The method of manufacturing a heat transfer sheet, wherein the shape factor (S) is obtained by dividing the area (M) of the pressure receiving surface (21a) by the area (F) of the free surface (21b).

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