JP6597301B2 - Battery module fixing structure - Google Patents

Description

  The present invention relates to a battery module fixing structure.

  Conventionally, as a battery mounted on a vehicle such as a forklift, for example, a battery pack in which a plurality of battery modules are accommodated in a housing is known. The battery module includes an array body in which a plurality of battery cells such as lithium ion secondary batteries are arrayed, and a restraining member that applies a restraining load to the array body in the array direction of the battery cells. End plates and brackets are respectively provided at the ends of the battery cells in the array, and the battery module and the housing are fastened via these brackets (see, for example, Patent Document 1).

JP, 2014-120340, A

  In the battery module, there is a case where an elastic body such as rubber is interposed between the battery cell at the end of the array and the end plate for the purpose of preventing breakage of the restraining load due to the expansion of the battery cell in use. When such an elastic body is interposed, if an impact load is applied to the battery module due to vehicle vibration or the like, it is assumed that the response to the load is delayed in the elastic body. In particular, with respect to the arrangement direction of the battery cells, most of the load may flow to the bracket located farther from the elastic body. In this case, it is conceivable that the fastening member slips on one side of the bracket that receives most of the load, and that the fastening state between the battery module and the housing is loosened.

  The present invention has been made to solve the above-described problems, and provides a battery module fixing structure capable of preventing loosening of the fastening state between the battery module and the housing even when an impact load is applied. With the goal.

  A battery module fixing structure according to an aspect of the present invention is a battery module fixing structure in which a battery module is fixed to a housing, and the battery module is an array body in which a plurality of battery cells are arranged. A restraining member that applies a restraining load to the array body in the battery cell array direction, an elastic body that is unevenly arranged on one side of the array body in the battery cell array direction, and an array end of the array body A pair of brackets that are respectively disposed and fastened to the housing by a fastening member, and the first fastening force between the first bracket far from the elastic body and the housing is closer to the elastic body This is larger than the second fastening force between the second bracket and the housing.

  In this battery module fixing structure, the first fastening force between the first bracket far from the elastic body and the housing is the first fastening force between the second bracket near the elastic body and the housing. It is larger than the fastening force of 2. For this reason, when an impact load is applied to the battery module, even if most of the load flows in the first bracket located far from the elastic body in the battery cell arrangement direction, It is possible to prevent looseness from occurring in the fastening state.

  The restraining member has a pair of end plates provided so as to sandwich the array body, and restraint bolts that fasten the end plates, and the array body is disposed adjacent to the elastic body, A middle plate through which the restraint bolt is inserted may be arranged.

  According to such a configuration, when an impact load is applied to the battery module, the load can be shared by the second bracket via the middle plate and the restraint bolt. Therefore, the ratio between the first fastening force and the second fastening force does not become excessive, and the configuration can be prevented from becoming complicated. In particular, the load in the direction orthogonal to the arrangement direction of the battery cells (the in-plane direction of the middle plate) can be substantially equally distributed to the first bracket and the second bracket via the middle plate and the restraining bolt. It becomes.

  Further, the ratio of the first fastening force to the second fastening force is set based on the ratio of half the total weight of the battery module and the weight of the other side of the battery module sandwiching the elastic body. Also good. Thereby, the ratio of the first fastening force and the second fastening force does not become excessive, and the configuration can be prevented from becoming complicated.

  Further, the ratio of the first fastening force to the second fastening force may be set based on the weight ratio between the one side and the other side across the elastic body in the battery module. Thereby, the ratio of the first fastening force and the second fastening force does not become excessive, and the configuration can be prevented from becoming complicated.

  Further, a sheet-like heat transfer member and a sheet-like friction reducing member may be interposed between the array and the housing. A sheet-like heat transfer member may be disposed between the array body and the housing in order to efficiently dissipate heat generated in the battery cells to the housing.

  In this case, in consideration of expansion of the battery cell during use, it is preferable to interpose a sheet-like friction reducing member between the array and the housing in order to allow displacement of the battery cell due to expansion. On the other hand, when a sheet-like friction reducing member is interposed between the array and the housing, it is considered that the fastening member is likely to slip when a load flows through the bracket. On the other hand, in this battery module fixing structure, the first fastening force is larger than the second fastening force as described above, and therefore, sheet-like friction reduction between the array and the housing is performed. Even when the member is interposed, it is possible to suitably prevent looseness in the fastening state between the bracket and the housing.

  According to the present invention, it is possible to prevent looseness in the fastening state between the battery module and the housing even when an impact load is applied.

It is a perspective view which shows one Embodiment of the battery pack to which the fixing structure of a battery module is applied. It is sectional drawing which shows the fixation structure of the battery module with respect to a housing | casing. It is a principal part expansion perspective view which shows the structure by the side of a 1st bracket. It is a principal part expansion perspective view which shows the structure by the side of the 2nd bracket.

  Hereinafter, preferred embodiments of a battery module fixing structure according to one aspect of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of a battery pack to which a battery module fixing structure is applied. As shown in the figure, the battery pack 1 includes a housing 2 having a substantially rectangular parallelepiped shape. The housing 2 has a rectangular flat plate-shaped bottom plate 3, a side plate 4 standing on the periphery of the bottom plate 3, and a top plate 5 that closes an opening defined by the side plate 4.

  A plurality of battery modules 11 are accommodated in the housing 2. In the present embodiment, the battery modules 11 are arranged in two rows in the upper and lower stages in the accommodation space in the housing 2. Each battery module 11 is fixed to the inner surface of the side plate 4 via brackets 23 (23A, 23B) described later.

  FIG. 2 is a cross-sectional view showing a structure for fixing the battery module to the housing. As shown in the figure, the battery module 11 includes an array 13 including a plurality of battery cells 12 and a restraining member 14 that applies a restraining load to the array 13 in the array direction of the battery cells 12. . The array body 13 further includes a middle plate 15, an elastic body 16, and a heat transfer plate 17. The restraining member 14 includes a pair of end plates 18 and 18 and a long restraint bolt 19 and a nut 20 that fasten the end plates 18 and 18 together.

  The battery cell 12 is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery. In the present embodiment, seven battery cells 12 are included in the array 13, and each battery cell 12 is arrayed while being held by a cell holder K that forms a frame. The battery cell 12 is configured by accommodating an electrode assembly in a case into which a non-aqueous electrolyte is injected. The electrode assembly is obtained by stacking a positive electrode, a negative electrode, and a separator in a predetermined order. In this embodiment, a sheet-like positive electrode is accommodated in a bag-shaped separator, and a bag-shaped separator and a sheet-shaped negative electrode each containing a positive electrode are alternately stacked.

  The middle plate 15 is a plate disposed between the end plates 18 and 18. The middle plate 15 has a substantially rectangular plate shape corresponding to the shape of the battery cell 12 as viewed from the arrangement direction, and is disposed adjacent to the battery cell 12 located on the most end side in the arrangement direction. The middle plate 15 is provided with an insertion hole (not shown) through which a restraining bolt 19 described later is inserted.

  The elastic body 16 is a member used for the purpose of preventing the battery cell 12 and the end plate 18 from being damaged by a restraining load when the battery cell 12 is expanded. The elastic body 16 is formed in a rectangular plate shape by a rubber sponge made of urethane, for example. The elastic body 16 is arranged unevenly on one side of the array body 13 in the array direction of the battery cells 12. In the present embodiment, the elastic body 16 is disposed between the middle plate 15 and the end plate 18 on one side of the array body 13. Examples of other forming materials of the elastic body 16 include ethylene propylene diene rubber (EPDM), chloroprene rubber, and silicon rubber. The elastic body 16 is not limited to rubber and may be a spring material or the like.

  The heat transfer plate 17 is a member for radiating the heat generated in the battery cells 12 to the housing 2 side. The heat transfer plate 17 is formed in a plate shape by a material having heat conductivity (for example, metal), and comes into contact with a side surface in the arrangement direction of the battery cells 12 (one side surface in the thickness direction of the battery cells 12). And a facing portion 22 that faces one side surface of the battery cell 12 in the width direction.

  The contact portion 21 is formed in a rectangular shape corresponding to the shape of one side surface in the arrangement direction of the battery cells 12. The contact portion 21 is fixed to one side surface in the arrangement direction of the battery cells 12 using a double-sided tape (not shown) or the like. As the double-sided tape, it is preferable to use a tape having a base material such as polypropylene, for example, from the viewpoint of ensuring electrical insulation and heat transfer. The facing portion 22 is formed in a rectangular shape corresponding to the shape of the side surface in the width direction of the battery cell 12. The facing portion 22 is provided at a substantially right angle with respect to the abutting portion 21 at one end portion in the width direction of the abutting portion 21 (the width direction of the battery cell 12), and is arranged to cover the outer surface side of the frame portion of the cell holder K Has been.

  Similar to the middle plate 15, the end plate 18 has a substantially rectangular plate shape corresponding to the shape of the battery cell 12 as viewed from the arrangement direction, and is arranged at one array end and the other array end of the array body 13. Each is arranged. With respect to the end plates 18, 18, the restraint bolt 19 is disposed so as to pass through the middle plate 15 and the other end plate 18 from one end plate 18, and the nut 20 is a restraint bolt protruding from the other end plate 18. 19 is screwed into the tip portion. Thereby, the battery cell 12, the middle plate 15, the elastic body 16, and the heat transfer plate 17 constituting the array body 13 are sandwiched and unitized, and a restraining load is applied to the array body 13.

  A pair of brackets 23 and 23 are used for the structure M for fixing the battery module 11 to the housing 2. The bracket 23 includes a substantially rectangular first plate-like portion 23a and a second plate provided at a substantially right angle with respect to the first plate-like portion 23a on one long side of the first plate-like portion 23a. And has an L-shape as a whole. The first plate-like portion 23a is fastened to the outer surface side of the end plate 18 by bolts 24 (see FIGS. 3 and 4). The second plate-like portion 23 b protrudes from the end plate 18 so as to be substantially flush with the facing portion 22 of the heat transfer plate 17 in the array 13.

  The battery module 11 is disposed in the housing 2 such that the second plate-like portion 23b of the bracket 23 and the opposed portion 22 of the heat transfer plate 17 face the inner surface side of the side plate 4, and are attached by bolts (fastening members) 25. The second plate portion 23 b is fixed to the housing 2 by fastening the second plate portion 23 b to the side plate 4.

  Further, as shown in FIG. 2, a sheet-like heat transfer member 26 and a sheet-like friction reducing member 27 are interposed between the battery module 11 and the side plate 4. The heat transfer member 26 is disposed on the side plate 4 side. The heat transfer member 26 is formed, for example, by curing a liquid heat transfer material (TIM: Thermal Interface Material). An example of the heat transfer material constituting the heat transfer member 26 is polyurethane. The heat transfer member 26 may be in the form of a gel or have adhesiveness as long as it maintains a constant volume and sheet shape.

  The friction reducing member 27 is disposed between the battery module 11 and the heat transfer member 26. The friction reducing member 27 may or may not have electrical insulation, but in the present embodiment, the friction reducing member 27 is formed of a material having electrical insulation and constant heat transfer. An example of such a material is polyethylene terephthalate.

  The heat transfer member 26 and the friction reducing member 27 are fastened together by a bolt 25 that fastens the bracket 23 to the side plate 4. With the arrangement of the heat transfer member 26, a heat transfer path is established from the battery cell 12 to the side plate 4 via the contact portion 21 of the heat transfer plate 17, the facing portion 22, and the heat transfer member 26. The generated heat is efficiently radiated to the housing 2 side. Further, due to the arrangement of the friction reducing member 27, even when the heat transfer member 26 is arranged between the battery module 11 and the side plate 4, displacement due to expansion of the battery cell 12 when the battery pack 1 is used is allowed.

  In the battery module 11, as described above, the elastic body 16 is interposed between the battery cell 12 at the end of the array 13 and the end plate 18 for the purpose of preventing breakage of the restraint load due to expansion of the battery cell 12 during use. Is intervening. When such an elastic body 16 is interposed, if an impact load is applied to the battery module 11 due to the vibration of the vehicle on which the battery pack 1 is mounted, it is assumed that the response to the load in the elastic body 16 is delayed. In particular, with respect to the arrangement direction of the battery cells 12, most of the load may flow to the bracket 23 located far from the elastic body 16. In this case, it is conceivable that the bolt 25 is slipped by the bracket 23 on one side that receives most of the load, and the fastening state between the battery module 11 and the housing 2 is loosened.

  With respect to such a problem, in the fixing structure M of the battery module 11, a fastening force (first fastening force) between the bracket 23 (first bracket 23A) far from the elastic body 16 and the housing 2 is provided. However, it is larger than the fastening force (second fastening force) between the bracket 23 (second bracket 23B) closer to the elastic body 16 and the housing 2. The fastening force by the bolts 25 between the bracket 23 and the housing 2 is determined based on the product of the number of bolts 25 and the torque. Therefore, the first fastening force and the second fastening force can be adjusted by adjusting the number of bolts 25, the screw diameter of the bolts 25, and the like. Further, the fastening force can be adjusted by increasing the hardness of the material of the bolt 25.

  The ratio of the first fastening force to the second fastening force is, for example, half the total weight of the battery module 11 and the battery module 11 when the middle plate 15 is disposed between the end plates 18 and 18. Is set based on the ratio to the weight of the other side of the elastic body 16 sandwiched therebetween. Further, the ratio of the first fastening force to the second fastening force is such that when the middle plate 15 is not disposed between the end plates 18, 18, one side and the other side of the battery module 11 sandwiching the elastic body 16. It is set based on the weight ratio on the side.

  The weight on one side of the battery module 11 is, for example, the weight of the configuration located on the first bracket 23A side from the center line L (see FIG. 2) in the thickness direction of the elastic body 16. In the example of FIG. 2, as one side weight, the battery cell 12, cell holder K, one part of the elastic body 16, located on the first bracket 23A side from the center line L, the heat transfer plate 17, the middle plate 15, the end The weight of the plate 18 and the first bracket 23A is included.

  The weight on the other side of the battery module 11 is, for example, the weight of the configuration located on the second bracket 23B side with respect to the center line L in the thickness direction of the elastic body 16 (see FIG. 2). In the example of FIG. 2, as the weight on the other side, the battery cell 12, the cell holder K, the other part of the elastic body 16, the end plate 18, and the second bracket 23B located on the second bracket 23B side with respect to the center line L. The weight of is included.

  In the present embodiment, as described above, the middle plate 15 is disposed between the end plates 18 and 18 in the battery module 11. Further, the middle plate 15 is inserted with a restraining bolt 19 that fastens the end plates 18 and 18 and applies a restraining load to the array 13 (see FIG. 2). For this reason, with respect to the load in the direction orthogonal to the arrangement direction of the battery cells 12 (in-plane direction of the middle plate 15), the restraint bolt 19 is moved to the middle plate 15 (for example, the restraint bolt 19) when an impact load is applied to the battery module 11. The inner plate), the vibration in the in-plane direction of the middle plate 15 is regulated. Thereby, it is suppressed that a rotational moment is added to the fastening surface of the first bracket 23 </ b> A far from the elastic body 16. Therefore, the first bracket 23A and the second bracket 23B can be distributed substantially equally through the middle plate 15 and the restraining bolt 19.

  The force W1 applied to the first bracket 23A is represented by weight × vibration acceleration × gravity acceleration on one side of the battery module 11 with the elastic body 16 interposed therebetween. Further, the force W2 applied to the second bracket 23B is represented by the total weight of the battery module 11 × 2 vibration acceleration × gravity acceleration. Therefore, the first fastening force: second fastening force = W1: W2 = weight on one side of the battery module 11 with the elastic body 16 in between: the total weight of the battery module 11/2.

  For the load in the direction orthogonal to the arrangement direction of the battery cells 12, the first fastening force and the second fastening force may be equal. In this embodiment, the fastening force of the two bolts 25 is sufficient. Each is set. On the other hand, the load in the arrangement direction of the battery cells 12 is set based on the above-described weight ratio, and in this embodiment, the fastening force of two bolts 25 is further added only to the first fastening force. Therefore, in the battery module 11, the first bracket 23A is fastened to the side plate 4 of the housing 2 by the four bolts 25 as shown in FIG. 3, and the second bracket 23B is as shown in FIG. It is fastened to the side plate 4 of the housing 2 by two bolts 25.

  Note that the rotational moment when an impact load is applied to the battery module 11 is amplified according to the distance. Therefore, the middle plate 15 is preferably arranged in the vicinity of the elastic body 16, and more preferably arranged adjacent to the elastic body 16 as in the present embodiment. Even when the middle plate 15 is disposed, it does not contribute to the regulation of vibration with respect to the load in the arrangement direction of the battery cells 12, but the load is not amplified according to the distance unlike the rotation moment.

  As described above, in the fixing structure M of the battery module 11, the first fastening force between the first bracket 23 </ b> A far from the elastic body 16 and the housing 2 is closer to the elastic body 16. It is larger than the second fastening force between the second bracket 23B and the housing 2. For this reason, when an impact load is applied to the battery module 11, even if most of the load in the arrangement direction of the battery cells 12 flows to the first bracket 23 </ b> A located far from the elastic body 16, the first bracket It is possible to prevent looseness in the fastening state between 23A and the housing 2.

  Further, in the fixing structure M of the battery module 11, the restraining member 14 is configured by a pair of end plates 18, 18 provided so as to sandwich the array 13 and a restraining bolt 19 that fastens the end plates 18, 18 together. The array body 13 is provided with a middle plate 15 that is disposed adjacent to the elastic body 16 and through which the restraint bolt 19 is inserted.

  Thereby, when an impact load is applied to the battery module 11, the load can be shared by the second bracket 23 </ b> B via the middle plate 15 and the restraint bolt 19. Therefore, the ratio between the first fastening force and the second fastening force does not become excessive, and the configuration can be prevented from becoming complicated. In particular, the load in the direction orthogonal to the arrangement direction of the battery cells 12 can be substantially equally distributed to the first bracket 23A and the second bracket 23B via the middle plate 15 and the restraint bolt 19.

  Further, in the fixing structure M of the battery module 11, based on the ratio of the half weight of the total weight of the battery module 11 and the weight of the other side of the battery module 11 with the elastic body 16 sandwiched, the second fastening force is A first fastening force ratio is set. Thereby, the ratio of the first fastening force and the second fastening force does not become excessive, and the configuration can be prevented from becoming complicated.

  In the battery module 11 fixing structure M, a sheet-like heat transfer member 26 and a sheet-like friction reducing member 27 are interposed between the array 13 and the housing 2. A heat transfer path from the battery cell 12 to the housing 2 is established by the heat transfer member 26, and heat generated in the battery cell 12 can be efficiently radiated to the housing 2 side. Further, the friction reducing member 27 allows displacement of the battery cell 12 due to expansion.

  When the friction reducing member 27 is interposed, it is conceivable that the bracket slips easily when a load flows to the bracket 23. On the other hand, in the battery module 11 fixing structure M, the first fastening force is larger than the second fastening force, so that the sheet-like friction reduction between the array 13 and the housing 2 is performed. Even when a member is interposed, it is possible to suitably prevent looseness in the fastening state between the bracket 23 (particularly, the first bracket 23A) and the housing 2.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the battery module 11 in which the middle plate 15 is disposed between the end plates 18 and 18 is illustrated, but the middle plate 15 may not necessarily be disposed. When the middle plate 15 is not arranged, it is necessary to consider the delay in response due to the elastic body 16 with respect to the load in the direction orthogonal to the arrangement direction of the battery cells 12. For this reason, compared with the said embodiment, it is suitable to set large the ratio of the 1st fastening force with respect to a 2nd fastening force, As mentioned above, while sandwiching the elastic body 16 in the battery module 11, It is set based on the weight ratio of the side and the other side.

  In this case, the force W <b> 1 applied to the first bracket 23 </ b> A is generated by vibration in a direction orthogonal to the direction of weight × vibration acceleration × gravity acceleration × battery cell 12 on one side across the elastic body 16 in the battery module 11. It is represented by the amplification power α. Further, the force W2 applied to the second bracket 23B is represented by weight × vibration acceleration × gravity acceleration on the other side of the battery module 11 with the elastic body 16 interposed therebetween. Therefore, first fastening force: second fastening force = W1: W2 = weight on one side of the battery module 11 with the elastic body 16 interposed therebetween: weight on the other side of the battery module 11 with the elastic body 16 sandwiched × amplifying force α.

  In the above-described embodiment, the elastic body 16 is disposed between the end plate 18 and the middle plate 15. However, the elastic body 16 is unevenly distributed on one side of the array body 13 in the array direction of the battery cells 12. If so, it may be arranged at an arbitrary position.

  DESCRIPTION OF SYMBOLS 2 ... Case, 11 ... Battery module, 12 ... Battery cell, 13 ... Array, 14 ... Restraint member, 15 ... Middle plate, 16 ... Elastic body, 18 ... End plate, 19 ... Restraint bolt, 23 ... Bracket, 23A ... 1st bracket, 23B ... 2nd bracket, 25 ... Bolt (fastening member), 26 ... Heat transfer member, 27 ... Friction reducing member, M ... Fixed structure.

Claims (5)

A battery module fixing structure in which the battery module is fixed to the housing,
The battery module is
An array formed by arranging a plurality of battery cells;
A restraining member for applying a restraining load in the arrangement direction of the battery cells to the array;
An elastic body that is unevenly arranged on one side of the arrangement direction of the battery cells in the array;
A pair of brackets that are respectively arranged at the array ends of the array and are fastened to the housing by a fastening member;
The first fastening force between the first bracket farther from the elastic body and the housing is the second fastening force between the second bracket closer to the elastic body and the housing. Battery module fixing structure that is larger than The restraining member has a pair of end plates provided so as to sandwich the array, and a restraining bolt that fastens the end plates,
2. The battery module fixing structure according to claim 1, wherein a middle plate that is disposed adjacent to the elastic body and through which the restraint bolt is inserted is disposed in the array.   A ratio of the first fastening force to the second fastening force is set based on a ratio of a half weight of the total weight of the battery module and a weight of the other side of the battery module sandwiching the elastic body. The structure for fixing a battery module according to claim 1.   3. The battery module according to claim 2, wherein a ratio of the first fastening force to the second fastening force is set based on a weight ratio between one side and the other side of the battery module sandwiching the elastic body. Fixed structure.   The battery module fixing structure according to any one of claims 1 to 4, wherein a sheet-like heat transfer member and a sheet-like friction reducing member are interposed between the array and the housing. .

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