JP6589690B2 - Battery pack - Google Patents

Description

  The present invention relates to a battery pack.

  There is known a cooling structure in which a deformable heat transfer sheet is provided between a cooling surface of a battery module in which a plurality of battery cells are stacked and a cooling plate (see, for example, Patent Document 1).

JP2013-122817A

  In the above cooling structure, for example, the battery cell may expand or contract in the stacking direction of the battery cell due to charge / discharge of the battery cell. In such a case, a force in the battery cell stacking direction is applied to the heat transfer sheet, and the heat transfer sheet may be displaced in the battery cell stacking direction. When the heat transfer sheet is displaced, peeling occurs at the interface between the cooling surface of the battery module and the heat transfer sheet or at the interface between the heat transfer sheet and the cooling plate. When peeling occurs, the contact area between the cooling surface of the battery module and the heat transfer sheet or the contact area between the heat transfer sheet and the cooling plate decreases. Further, if the force applied to the heat transfer sheet is large, the heat transfer sheet may be cracked or broken. As a result, the heat dissipation from the battery module to the cooling plate is reduced.

  An object of this invention is to provide the battery pack which can suppress the fall of the heat dissipation of the battery module resulting from expansion | swelling of a battery cell.

  A battery pack according to an aspect of the present invention includes an array including a plurality of battery cells arranged in a first direction and a plurality of heat transfer members connected to each of the plurality of battery cells, and a first of the array A battery module having a pair of end plates provided at both ends in the direction, a fixed member to which the battery module is fixed, a heat transfer layer provided between the array and the fixed member, and a heat transfer layer, A sliding sheet provided between the fixed member and having a sliding surface slidable along the first direction on the fixed member side, and the heat transfer layer includes a plurality of heat transfer members, respectively. A plurality of heat transfer portions that are movable together with each of the plurality of heat transfer members and independently of each other in the first direction, and the sliding sheet is fixed to the plurality of heat transfer portions. Arranged between a plurality of first parts with which the end surfaces on the member side abut each other and adjacent first parts It is having, a plurality of second portions of retractable in the first direction.

  In this battery pack, the plurality of heat transfer portions of the heat transfer layer are individually provided for each of the plurality of heat transfer members of the battery module, and can move in the first direction independently of each other. When a certain battery cell expands in the first direction, adjacent battery cells and heat transfer members are pushed in the first direction. The pressed battery cell and the heat transfer member move in the first direction together with the heat transfer portion corresponding to the heat transfer member. Along with this movement, the first portion with which the heat transfer section abuts slides relative to the fixed member and moves in the first direction. Since the second portion is extendable and contractible, at this time, the heat transfer section moves on the fixed member while maintaining a contact state on both the heat transfer member side surface and the fixed member side surface. Even when a plurality of battery cells expand, the same action as described above can occur at a plurality of locations. In this way, a heat transfer structure that can follow the expansion of the battery cell is realized by the cooperation of the heat transfer section provided individually for each battery cell and the extendable sliding sheet. Therefore, the heat dissipation through the heat transfer layer can be maintained. As a result, it is possible to suppress a decrease in heat dissipation of the battery module due to the expansion of the battery cells.

  The second portion of the sliding sheet enters the interval when the interval between adjacent heat transfer portions is the smallest, and is pulled by the first portion and increases in the first direction as the interval between the heat transfer portions increases. According to the sliding sheet of such a form, stretchability is implement | achieved by the 2nd part spreading. Therefore, each heat transfer part can be smoothly moved with a simple configuration. Even when the interval between the heat transfer portions is the smallest, the second portion enters the interval between the heat transfer portions, so that the increase in size in the first direction is suppressed.

  The pair of end plates are fixed to the fixed member, and the battery module includes at least one elastic body disposed between at least one of the pair of end plates and the array body. According to this configuration, the expansion amount can be absorbed by the elastic body compressively deforming according to the expansion amount by which the battery cell expands.

  At least one of the pair of end plates is slidable in the first direction. According to this configuration, the expansion amount can be absorbed by sliding at least one end plate according to the expansion amount by which the battery cell expands.

  The amount of looseness of the sliding sheet, which is the sum of the differences between the contraction and the extension of the second portion, is larger than the product of the expansion amount in the first direction per battery cell and the number of battery cells in the battery module. According to this configuration, even when all the battery cells are expanded, the sliding sheet has a sufficient amount of slack, and can be expanded following the expansion.

  The frictional resistance between the sliding sheet and the surface of the fixed member is smaller than the frictional resistance between the sliding sheet and the end surfaces of the plurality of heat transfer units. According to this configuration, the first portion of the sliding sheet slides with respect to the non-fixing member. There is no deviation between the sliding sheet and the heat transfer section, and the first portion moves integrally with the heat transfer section. Therefore, the heat dissipation through the heat transfer layer is reliably maintained.

  The battery pack further includes another sliding sheet provided between the sliding sheet and the fixed member, and the other sliding sheet is fixed to the fixed member and at least the first sliding sheet. It has a flat surface that faces and contacts the part. According to this configuration, the first portion of the sliding sheet slides with respect to the surface of another sliding sheet. There is no deviation between the sliding sheet and the heat transfer section, and the first portion moves integrally with the heat transfer section. Therefore, the heat dissipation through the heat transfer layer is reliably maintained.

  According to some embodiments of the present invention, it is possible to suppress a decrease in heat dissipation of the battery module due to the expansion of the battery cells.

It is a figure which shows the partial structure of the battery pack which concerns on 1st Embodiment of this invention. It is sectional drawing along the II-II line of FIG. It is a disassembled perspective view which shows the partial structure of the battery module in FIG. 4A is a cross-sectional view showing an example of a sliding sheet mounting method, and FIG. 4B is a cross-sectional view showing another example of a sliding sheet mounting method. It is sectional drawing which shows the state which each battery cell of the battery module shown by FIG. 1 and FIG. 2 expanded. It is sectional drawing which shows the partial structure of the battery pack which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the partial structure of the conventional battery pack.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  As shown in FIGS. 1 and 2, the battery pack 100 includes a battery module 1 having a plurality of battery cells 4, a housing 2 that houses the battery module 1, and heat generated in the battery module 1. And a heat transfer layer 3 for transmitting heat to the side to dissipate heat. The battery module 1 is accommodated in the housing 2. The battery module 1 is fixed to the side wall (fixed member) 2 a of the housing 2. The heat transfer layer 3 is disposed between the battery module 1 and the side wall 2 a of the housing 2. The battery pack 100 can include, for example, a plurality of battery modules 1 arranged along the side wall 2a, but only one battery module 1 is illustrated here.

  The battery module 1 has an array 10 including a plurality of battery cells 4 and a plurality of heat transfer plates (heat transfer members) 6. The number of battery cells 4 is, for example, seven. The battery cells 4 are individually held by the cell holder 20. The heat transfer plate 6 is provided for each of the battery cells 4. Therefore, the number of heat transfer plates 6 is also 7 as an example. The battery cells 4 and the heat transfer plates 6 are alternately arranged along the first direction D to form an array 10.

  The battery cell 4 is demonstrated with reference to FIG. As shown in FIG. 3, the battery cell 4 is electrically connected to the electrode assembly 11, the case 12 that houses the electrode assembly 11, and the electrodes (each of the positive electrode and the negative electrode) of the electrode assembly 11, A pair of terminals 13 protruding from the case 12. The electrode assembly 11 includes a plurality of positive electrodes (not shown) and a negative electrode (not shown), and a separator (not shown) disposed between the positive electrode and the negative electrode. The positive electrode and the negative electrode are alternately stacked via separators. The stacking direction of the positive electrode and the negative electrode substantially coincides with the arrangement direction (first direction D) of the battery cells 4.

  The case 12 has a rectangular parallelepiped shape. Case 12 includes a pair of side surfaces 12a and 12b facing each other, a pair of side surfaces 12c and 12d facing each other, and an upper surface 12e and a bottom surface 12f facing each other. The side surfaces 12a and 12b are surfaces along the first direction D. The side surfaces 12c and 12d are surfaces along a direction intersecting the first direction D, and connect the side surface 12a and the side surface 12b to each other. The terminal 13 protrudes from the upper surface 12e.

  The cell holder 20 includes a pair of side wall portions 20a, 20b facing each other, a back surface portion 20e, and a bottom wall portion 20f. The side wall portions 20a and 20b have a rectangular plate shape. The back surface portion 20e has a rectangular plate shape, and connects the side wall portion 20a and the side wall portion 20b to each other at one end in the longitudinal direction of the side wall portions 20a and 20b. The bottom wall portion 20f has a rectangular plate shape, and connects the side wall portion 20a and the side wall portion 20b to each other at the other end portion in the longitudinal direction of the side wall portions 20a and 20b.

  In the cell holder 20, a rectangular parallelepiped space portion into which the battery cells 4 are fitted is defined by the side wall portions 20a, 20b, the back surface portion 20e, and the bottom wall portion 20f. The side wall portions 20a and 20b are respectively disposed on the side surfaces 12a and 12b of the case 12 when the battery cell 4 is fitted in the space portion. Similarly, the back surface portion 20 e is disposed on the side surface 12 d in the vicinity of the top surface 12 e of the case 12. Furthermore, the bottom wall portion 20 f is disposed on the bottom surface 12 f of the case 12.

  A pair of protruding portions 21 are provided on the back surface portion 20e. The protruding portion 21 has a rectangular parallelepiped shape. The protruding portion 21 extends along the first direction D. The protruding portion 21 is disposed on the upper surface 12 e of the case 12 and between the pair of terminals 13 when the battery cell 4 is fitted into the space portion of the cell holder 20. The projecting portion 21 is formed with a through hole 21h along the extending direction. Bolts 32 (see FIG. 1) are inserted through the through holes 21h.

  A pair of projecting portions 22 is provided at a connection portion between the bottom wall portion 20f and the side wall portions 20a and 20b. The protruding portion 22 has a rectangular parallelepiped shape. The projecting portion 22 extends along the first direction D. When the battery cell 4 is fitted in the space portion of the cell holder 20, the protruding portion 22 is disposed at the end on the side surfaces 12 a and 12 b side of the bottom surface 12 f of the case 12. The protruding portion 22 is formed with a through hole 22h along the extending direction. Bolts 32 (see FIG. 1) are inserted through the through holes 22h.

  The heat transfer plate 6 includes a rectangular plate-shaped main body portion 6a and a rectangular plate-shaped extending portion 6b. The heat transfer plate 6 is formed in an L-shaped plate shape by the main body portion 6a and the extending portion 6b. The main body 6a is disposed on the side surface 12d of the battery cell 4 (case 12). The extending portion 6b extends from the main body portion 6a along the first direction D and is disposed on the side surface 12a of the battery cell 4 (case 12). In particular, the extending portion 6 b is disposed on the side surface 12 a via the side wall portion 20 a of the cell holder 20. The heat transfer plate 6 receives the heat generated in the battery cell 4 by the main body 6 a coming into contact with the side surface 12 d of the battery cell 4. In this way, the heat transfer plate 6 is connected to each of the battery cells 4.

  As shown in FIG. 2, in the array 10 of the battery modules 1, the main body portion 6 a of the heat transfer plate 6 is sandwiched between two adjacent battery cells 4. The main body 6 a is in contact with the side surface 12 d of one battery cell 4 and is in contact with the side surface 12 c of the other battery cell 4. One end portion 10 a of the array 10 in the first direction D is a main body portion 6 a of the heat transfer plate 6 connected to the battery cell 4 located at one end portion in the first direction D. The other end 10 b of the array 10 in the first direction D is the side surface 12 c of the battery cell 4 located at the other end in the first direction D.

  As shown in FIGS. 1 and 2, the battery module 1 has a pair of end plates 31 provided on each of the one end 10 a and the other end 10 b of the array 10 in the first direction D. The pair of end plates 31 are fixed to the side wall 2 a and restrain the plurality of battery cells 4 and the plurality of heat transfer plates 6. As an example, the end plate 31 is formed in an L-shaped plate shape by a rectangular plate-shaped main body portion 31a and a rectangular plate-shaped fixing portion 31b. The main body 31 a is disposed on the side surfaces 12 c and 12 d of the battery cell 4. The fixing portion 31b is provided so as to protrude from the main body portion 31a along the first direction D.

  The bolt 32 is inserted into the through holes 21 h and 22 h of the cell holder 20 holding the battery cell 4 and the through holes provided in the end plate 31. The nut 33 is screwed onto the end of the bolt 32 so that the end plates 31 are fastened to each other. Thereby, a restraining load is applied to the battery cell 4 via the end plate 31.

  One elastic body 36 is interposed between the end plate 31 provided on the other end 10 b side and the array body 10. The elastic body 36 has elasticity in the first direction D, and is made of, for example, rubber. The elastic body 36 is in contact with the end plate 31 and the side surface 12c of the battery cell 4 forming the other end portion 10b of the array 10. The elastic body 36 is disposed between the end plate 31 and the side surface 12c, and is in close contact with both of them. The elastic body 36 contracts according to the movement of the battery cell 4, the cell holder 20, and the heat transfer plate 6 in the first direction D.

  The battery module 1 is fixed to the side wall 2a of the housing 2 at both ends in the first direction D. More specifically, the battery module 1 is fixed to the side wall 2a of the housing 2 using a bolt 31c inserted through the fixing portion 31b in a state where the fixing portion 31b of the end plate 31 is in contact with the inner surface of the side wall 2a. Is done.

  Then, with reference to FIG. 2, the heat-transfer structure X with which the battery pack 100 of this embodiment is provided is demonstrated. Between the array body 10 and the side wall 2 a of the housing 2, the above-described heat transfer layer 3 and one sliding sheet 40 are provided. The sliding sheet 40 is provided between the heat transfer layer 3 and the side wall 2a. The heat transfer structure X includes the heat transfer plate 6, the heat transfer layer 3, and the sliding sheet 40, and transfers heat generated in the battery cells 4 to the side wall 2a. The heat transfer structure X has the following configuration, thereby maintaining heat dissipation regardless of the deformation of the array 10 based on the movement of the battery cells 4 (that is, the expansion and contraction in the first direction D).

  The heat transfer layer 3 is a so-called thermal interface material (TIM) layer. In other words, the heat transfer layer 3 is a heat dissipation layer. The heat transfer layer 3 has a plurality of heat transfer portions 37 provided for each of the plurality of heat transfer plates 6. Each heat transfer part 37 has a rectangular parallelepiped shape. The heat transfer part 37 can be, for example, a so-called silicone TIM in which a thermally conductive filler is kneaded into silicone. Each heat transfer part 37 may be a sheet-like TIM, or a liquid or paste-like TIM. When the heat transfer unit 37 is a liquid TIM, the heat transfer unit 37 is formed by using, for example, a liquid dispensing apparatus using a gear pump or the like and a robot that drives the discharge unit of the discharge apparatus. Is possible.

  Each heat transfer section 37 includes an end surface 37a disposed on the array body 10 side and an end surface 37b disposed on the side wall 2a side. The end surface 37 a of the heat transfer unit 37 is in surface contact with and closely contacts the extension 6 b of the heat transfer plate 6. The size of the heat transfer section 37, that is, the size of the end surface 37a can be set as appropriate. The end surface 37a may have, for example, an area that is the same as or slightly smaller than the extending portion 6b. The end surface 37a may have a larger area than the extending portion 6b. The end surface 37 b of the heat transfer unit 37 is in surface contact with and closely adheres to the surface 40 a of the sliding sheet 40.

  Each heat transfer section 37 is movable in the first direction D together with each heat transfer plate 6. Thus, the heat transfer layer 3 is divided into a plurality of heat transfer portions 37. The heat transfer section 37 provided individually corresponding to the heat transfer plate 6 (that is, corresponding to the battery cell 4) is configured to be movable in the first direction D independently of the other heat transfer sections 37. Has been.

  A space S (that is, a space or a gap) is formed between the heat transfer portions 37 arranged in the first direction D. Each heat transfer part 37 moves according to the movement of the battery cell 4, the cell holder 20, and the heat transfer plate 6 in the first direction D. As the heat transfer unit 37 moves, the width (size) of each interval S in the first direction D changes.

  The sliding sheet 40 is provided on the side wall 2a and has a larger area than the heat transfer layer 3 (the plurality of heat transfer portions 37) when projected onto the side wall 2a. The sliding sheet 40 includes a surface 40a disposed on the array body 10 side and a sliding surface 40b disposed on the side wall 2a side. The sliding sheet 40 is slidable with respect to the side wall 2a. That is, the sliding surface 40 b of the sliding sheet 40 can slide in the first direction D. The sliding sheet 40 is, for example, a slip sheet or a slide sheet. The sliding sheet 40 has thermal conductivity. The thickness of the sliding sheet 40 is, for example, 0.05 mm to 1 mm.

  The sliding sheet 40 may be, for example, a release paper including a silicone resin layer provided on one side or both sides of a base material. The sliding sheet 40 may include a silicone resin layer having a sliding surface 40b and a base material having a non-slidable surface 40a. The sliding sheet 40 may be sliding paper.

  The sliding sheet 40 may include a carbon sheet. The sliding sheet 40 may include a base material that supports the carbon sheet. For example, the sliding sheet 40 may include a carbon sheet having a sliding surface 40b and a base material having a non-slidable surface 40a. Examples of the carbon sheet include a graphite sheet. The thermal conductivity of the carbon sheet is, for example, about 2 to 1950 W / (m · K). The thickness of the carbon sheet is, for example, about 0.025 mm to 1 mm.

  The frictional resistance between the sliding sheet 40 and the surface 2 b of the housing 2 is smaller than the frictional resistance between the sliding sheet 40 and the end surface 37 b of the heat transfer section 37. Thereby, when the heat transfer part 37 tries to move in the first direction D, a slip may occur between the sliding surface 40b and the side wall 2a. At this time, no slip can occur between the end surface 37b and the surface 40a. Thus, the sliding sheet 40 has a plurality of first portions 41 that are in contact with the end surface 37b of the heat transfer section 37 and are in close contact with the end surface 37b. Each first portion 41 corresponds to each heat transfer portion 37 and is slidable with respect to the side wall 2a.

  On the other hand, the sliding sheet 40 has a plurality of second portions 42 arranged between the adjacent first portions 41. Each second portion 42 corresponds to the interval S described above, and is disposed within the interval S. The second portion 42 is bent into a V shape or a U shape within the interval S. That is, the sliding sheet 40 is a single sheet-like body formed by the first portions 41 and the second portions 42 being alternately continuous, but has a bellows shape as a whole. The number of V-shaped or U-shaped bent portions is not limited to one for one interval S, and a plurality of bent portions may be provided for one interval S.

  The second portion 42 of the sliding sheet 40 enters the interval S when the interval S between the adjacent heat transfer portions 37 is minimum (the state shown in FIG. 2), and the interval between the heat transfer portions 37. As S increases, the first portion 41 expands in the first direction D (see FIG. 5). That is, the sliding sheet 40 follows the heat transfer section 37 in the first portion 41 and expands and contracts in the first direction D in the second portion 42.

The length of the sliding sheet 40 in the first direction D will be described. The sliding sheet 40 has a slack amount (a length that can be slackened) according to a movement amount (displacement amount) of the plurality of heat transfer units 37. The amount of slack C in the first direction D of the sliding sheet 40 is the amount of expansion A in the first direction D per battery cell 4 (the maximum amount of expansion that can be assumed) and the number B of battery cells 4 in the battery module 1. It is larger than the product of (7 in this embodiment). The following formula (1) is established between the slack amount C of the sliding sheet 40 and the expansion amount A and the number B of the battery cells 4.
C> A × B (1)

  In forming the battery pack 100 having the above-described configuration, the bellows-shaped sliding sheet 40 can be mounted by various methods. As shown in FIG. 4A, a sliding sheet 40 in which a V-shaped or U-shaped fold is formed in advance may be prepared as the second portion 42. Thereafter, the sliding sheet 40 may be held by the suction device 60, and the sliding sheet 40 may be attached to the battery module 1 so that the second portion 42 is inserted at the interval S. Alternatively, as shown in FIG. 4B, a flat sliding sheet 40 stretched in the first direction D may be prepared. In the manufacturing process of the battery pack 100, the flat sliding sheet 40 is held by the suction device 60, and a V-shaped or U-shaped fold is formed so as to bring the suction position of the suction device 60 closer to each other. Portion 42 may be formed. Thereafter, the sliding sheet 40 may be attached to the battery module 1 so that the second portion 42 is inserted at the interval S.

  In the battery pack 100 of the present embodiment described above, the plurality of heat transfer portions 37 of the heat transfer layer 3 are individually provided for each of the plurality of heat transfer plates 6 of the battery module 1. The heat generated in each battery cell 4 is transmitted from the main body portion 6 a of the heat transfer plate 6 to the extending portion 6 b and is transmitted to the side wall 2 a via the heat transfer portion 37 and the sliding sheet 40. In the battery pack 100, the heat transfer units 37 are movable in the first direction D independently of each other. As shown in FIG. 5, when one or a plurality of battery cells 4 move in the first direction D due to expansion / contraction due to charge / discharge or expansion due to deterioration, the adjacent battery cells 4 and heat transfer plates 6 is pushed to one side (the other end portion 10b side) in the first direction D. The pressed battery cell 4 and the heat transfer plate 6 move in the first direction D together with the heat transfer portion 37 corresponding to the heat transfer plate 6. Along with this movement, the first portion 41 with which the heat transfer portion 37 abuts slides relative to the side wall 2a and moves in the first direction D. Since the second portion 42 is telescopic, the heat transfer section 37 moves on the side wall 2a while maintaining contact with both the end surface 37a on the heat transfer plate 6 side and the end surface 37b on the side wall 2a side. As described above, the heat transfer structure X that can follow the expansion of the battery cell 4 is realized by the cooperation of the heat transfer section 37 provided for each battery cell 4 and the slide sheet 40 that can be expanded and contracted. . Therefore, heat dissipation through the heat transfer layer 3 is ensured. As a result, it is possible to suppress a decrease in heat dissipation of the battery module 1 due to the expansion of the battery cells 4.

  In the conventional battery pack 200 as shown in FIG. 7, the heat transfer layer 203 is an integral TIM layer, and no sliding sheet is provided between the heat transfer layer 203 and the side wall 2a. Therefore, when one or a plurality of battery cells 4 move in the first direction D due to expansion / contraction due to charge / discharge or deterioration, etc., a shear force acts on the heat transfer layer 203, and the heat transfer layer 203 There is a possibility that peeling occurs at the interface between the heat transfer layer 203 and the surface 2b of the side wall 2a or at the interface between the heat transfer layer 203 and the heat transfer plate 6. Further, there is a possibility that a shear force acts on the heat transfer layer 203 and the heat transfer layer 203 itself is damaged. In the battery pack 100 of this embodiment, since each heat-transfer part 37 follows the movement of the battery cell 4 and the heat-transfer plate 6, such a situation is avoided and heat dissipation is ensured suitably.

  Further, according to the bellows-like sliding sheet 40, as shown in FIG. 5, the second portion 42 is expanded to ensure stretchability. Therefore, each heat transfer part 37 can be moved smoothly with a simple configuration. Even when the interval S between the heat transfer portions 37 is the smallest, the second portion 42 enters the interval S between the heat transfer portions 37 (see FIG. 2), and thus the enlargement in the first direction D is suppressed.

  According to the configuration including the pair of end plates 31 fixed to the side wall 2a and the elastic body 36, the expansion amount is absorbed by the elastic body 36 compressively deforming according to the expansion amount by which the battery cell 4 expands. Is done. The structure of the battery module 1 including the end plate 31 is not damaged.

  Since the above equation (1) is established between the slack amount C of the sliding sheet 40 and the expansion amount A and the number B of the battery cells 4, even if all the battery cells 4 are expanded, The sliding sheet 40 has a sufficient amount of slack. Thereby, the sliding sheet 40 can be extended following the expansion.

  Since the frictional resistance between the sliding sheet 40 and the surface 2b of the housing 2 is smaller than the frictional resistance between the sliding sheet 40 and the end surface 37b of the heat transfer section 37, the first portion 41 of the sliding sheet 40 has a side wall. Slide against 2a. There is no deviation between the sliding sheet 40 and the heat transfer section 37, and the first portion 41 moves integrally with the heat transfer section 37. Therefore, the heat dissipation through the heat transfer layer 3 is reliably maintained.

  Subsequently, a battery pack 100A according to the second embodiment will be described with reference to FIG. The heat transfer structure XA of the battery pack 100A is different from the heat transfer structure X of the first embodiment in that it further includes another sliding sheet 50 provided between the sliding sheet 40 and the side wall 2a. . Another sliding sheet 50 has a flat surface 50 a that faces and contacts the first portion 41 of the sliding sheet 40. Another sliding sheet 50 is fixed to the side wall 2a, for example, by the back surface 50b being bonded to the front surface 2b of the side wall 2a. As the sliding sheet 50, the same material as that of the sliding sheet 40 may be used. The thickness of the sliding sheet 50 may be the same as the thickness of the sliding sheet 40 or may be different from the thickness of the sliding sheet 40. The amount of slack does not need to be provided for the sliding sheet 50. The length of the sliding sheet 50 in the first direction D is equal to or longer than the length of the sliding sheet 40 when stretched. In addition, when using the sliding sheet 40 and the sliding sheet 50, the constraint conditions (above-mentioned constraint conditions in the heat transfer structure X) regarding frictional resistance can be ignored.

  According to this heat transfer structure XA, the first portion 41 of the sliding sheet 40 slides with respect to the surface 50 a of another sliding sheet 50. Similar to the heat transfer structure X of the first embodiment, no deviation occurs between the sliding sheet 40 and the heat transfer unit 37, and the first portion 41 moves integrally with the heat transfer unit 37. Therefore, the heat dissipation through the heat transfer layer 3 is reliably maintained. The battery pack 100A has the same operational effects as the first embodiment in addition to the above effects.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, the end plate 31 is not limited to the form fixed to the side wall 2a, and may be movable. That is, at least one of the pair of end plates 31 may be slidable in the first direction D. Specifically, the end plate 31 can be fixed by providing a long hole in the first direction D in the fixing portion 31b of the end plate 31 and inserting a bolt 31c into the long hole. According to this configuration, the expansion amount can be absorbed by sliding at least one end plate 31 according to the expansion amount by which the battery cell 4 expands. In that case, the elastic body 36 may be omitted.

  A pair of elastic bodies 36 may be disposed between both the pair of end plates 31 and the array body 10. The sliding sheet 40 is not limited to the above bellows shape. The sliding sheet 40 may be configured such that the flat second portion expands and contracts in the first direction D. The above formula (1) may not be established between the slack amount C of the sliding sheet 40 and the expansion amount A and the number B of the battery cells 4. If a slack amount is provided, a certain degree of expansion can be followed.

  The sliding sheet 40 is not limited to a single sheet-like body, and a plurality of sliding sheets 40 may be arranged side by side in the first direction D or the direction intersecting the first direction D. The arrangement of the cell holder 20 and the heat transfer plate 6 with respect to the battery cell 4 can be changed as appropriate. The structure of the heat transfer plate 6 is not limited to the above form, and various modifications can be employed.

  DESCRIPTION OF SYMBOLS 1 ... Battery module, 2 ... Housing | casing, 2a ... Side wall (fixed member), 3 ... Heat transfer layer, 4 ... Battery cell, 6 ... Heat transfer plate (heat transfer member), 10 ... Array, 10a ... One end part DESCRIPTION OF SYMBOLS 10b ... Other end part, 20 ... Cell holder, 31 ... End plate, 36 ... Elastic body, 37 ... Heat-transfer part, 40 ... Sliding sheet, 40a ... Surface, 40b ... Sliding surface, 41 ... 1st part, 42 ... 2nd part, 50 ... sliding sheet (another sliding sheet), 50a ... front surface, 50b ... back surface, 100, 100A ... battery pack, D ... first direction, S ... spacing, X, XA ... heat transfer structure .

Claims (7)

An array including a plurality of battery cells arranged in a first direction and a plurality of heat transfer members connected to each of the plurality of battery cells, and a pair provided at both ends of the array in the first direction A battery module having an end plate of
A fixed member to which the battery module is fixed;
A heat transfer layer provided between the array and the fixed member;
A sliding sheet provided between the heat transfer layer and the fixed member, and having a sliding surface on the fixed member side that is slidable along the first direction;
The heat transfer layer is provided on each of the plurality of heat transfer members, and includes a plurality of heat transfer portions that can move in the first direction together with each of the plurality of heat transfer members and independently of each other. Have
The sliding sheet is disposed between a plurality of first portions with which the fixed member side end surfaces of the plurality of heat transfer portions abut each other and the adjacent first portions, and is extendable in the first direction. And a plurality of second parts.   The second portion of the sliding sheet enters the interval when the interval between the adjacent heat transfer portions is minimum, and is pulled by the first portion as the interval between the heat transfer portions increases. The battery pack according to claim 1, spreading in a first direction. The pair of end plates are fixed to the fixed member,
The battery module is
The battery pack according to claim 1, further comprising at least one elastic body disposed between at least one of the pair of end plates and the array.   The battery pack according to claim 1, wherein at least one of the pair of end plates is slidable in the first direction.   The amount of looseness of the sliding sheet, which is the sum of the difference between the contraction and the extension of the second part, is the amount of expansion in the first direction per battery cell and the number of battery cells in the battery module. The battery pack according to any one of claims 1 to 4, wherein the battery pack is larger than a product.   The frictional resistance between the sliding sheet and the surface of the fixed member is smaller than the frictional resistance between the sliding sheet and the end surfaces of the plurality of heat transfer units. The battery pack according to claim 1. Further comprising another sliding sheet provided between the sliding sheet and the fixed member,
The said another sliding sheet | seat is fixed to the said to-be-fixed member, and has a flat surface which contacts and contacts at least the said 1st part of the said sliding sheet | seat. The battery pack described in 1.

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