WO2018173375A1

WO2018173375A1 - Battery module

Info

Publication number: WO2018173375A1
Application number: PCT/JP2017/043450
Authority: WO
Inventors: 崇酒井; 祐貴中條; 浩生植田; 泰有秋山; 文彦石黒; 直人守作; 正博山田; 英史大石; 加藤　裕久
Original assignee: 株式会社豊田自動織機
Priority date: 2017-03-22
Filing date: 2017-12-04
Publication date: 2018-09-27

Abstract

This battery module comprises: an array body having a plurality of battery cells arrayed along an arraying direction; a pair of end plates sandwiching the array body in the arraying direction; and a restraining member having a restraining bolt connecting the pair of end plates to one another, applying onto the array body a restraining load in the arraying direction. The restraining member includes, at a restraining bolt coupling position, an inner fastening part whereby one of the end plates is tightened from the inner side, and an outer fastening part whereby the one of the end plates is tightened from the outer side.

Description

Battery module

One aspect of the present invention relates to a battery module.

For example, Patent Document 1 discloses a conventional battery module. This conventional battery module includes an array body in which a plurality of battery cells are arrayed, an elastic member disposed at one end of the array body in the array direction of the battery cells, and a pair of end plates that sandwich the array body in the array direction. And a restraining member that applies a restraining load to the array body in the array direction. The restraining member includes a restraining bolt inserted into an insertion hole provided in each end plate, and a pair of nuts screwed to the protruding portions of the restraining bolt protruding outward from each end plate. The restraint load is applied to the array by tightening the pair of end plates from the outside with these nuts.

JP 2001-236937 A

In the battery module as described above, for example, when an impact load is applied due to vibration of a vehicle to be mounted, the position of the restraint bolt in the insertion hole may vary. When the position of the restraint bolt changes, the restraint bolt interferes with the end plate, and an excessive load may be applied to the restraint bolt at the interference position.

An aspect of the present invention has been made to solve the above-described problem, and an object thereof is to provide a battery module that can suppress interference between a restraining bolt and an end plate.

A battery module according to one aspect of the present invention includes an array having a plurality of battery cells arranged in the arrangement direction, a pair of end plates sandwiching the array in the arrangement direction, and the pair of end plates connected to each other. And a restraining member that applies a restraining load to the array body in the array direction, and the restraining member includes an inner fastening portion that tightens one end plate from the inside at a binding position of the restraining bolt and an outer side. Including an outer fastening portion to be tightened.

In this battery module, one end plate is tightened from both sides by the inner fastening portion and the outer fastening portion at the binding position of the restraint bolt, and a large axial force (fastening force) is generated between the two fastening portions. On the other hand, the restraint bolt can be firmly fixed. For this reason, interference with a restraint volt | bolt and an end plate can be suppressed.

A battery module according to an aspect of the present invention includes an array formed by arranging a plurality of battery cells, an elastic member that is unevenly arranged on one side of the array in the array direction of the battery cells, and an array arranged A pair of end plates sandwiched in the direction, and a restraint member that connects the pair of end plates to each other, and a restraining member that applies a restraining load in the array direction to the array body. An inner fastening portion for fastening one end plate from the inner side and an outer fastening portion for fastening from the outer side.

In this battery module, the end plate on one side is tightened from both sides by the inner fastening portion and the outer fastening portion at the binding position of the restraint bolt, and a large axial force (fastening force) is generated between the both fastening portions. It is possible to firmly fix the restraint bolt. For this reason, interference with a restraint volt | bolt and an end plate can be suppressed. In the end plate closer to the elastic member, the elastic member is deformed by an impact load, so that the position of the restraint bolt in the insertion hole is likely to fluctuate, and the problem that the restraint bolt interferes with the end plate is likely to occur. It is thought that. In this battery module, among the pair of end plates, the elastic member is unevenly arranged, so that the restraint bolt is fixed to the one end plate that is likely to interfere with the restraint bolt. For this reason, interference with a restraint volt | bolt and an end plate can be suppressed effectively.

The inner fastening part may be constituted by a nut screwed into the threaded part of the restraining bolt. In this case, the configuration can be simplified.

The restraint bolt is a stepped bolt in which a screw portion having a smaller diameter than that of the cylindrical portion is provided on the tip side of the cylindrical portion, and the inner fastening portion is constituted by a stepped portion between the cylindrical portion and the screw portion. Also good. In this case, the number of parts can be reduced.

The inner fastening part may be constituted by a collar part provided on the restraining bolt. In this case, the number of parts can be reduced. Further, the area of the contact surface between the inner fastening portion and the end plate can be easily secured.

The outer fastening portion may be constituted by a head of a restraining bolt. In this case, the configuration can be simplified and the number of parts can be reduced.

The outer fastening part may be constituted by a nut screwed into the threaded part of the restraining bolt. In this case, the configuration can be further simplified.

The inner surface of the one end plate may be provided with a stepped portion for engaging the inner fastening portion and the restraining bolt in the rotational direction to prevent the restraining bolt from rotating. In this case, it can suppress that a restraint volt | bolt rotates together at the time of the fastening of an outer side fastening part.

The outer surface of the one end plate may be provided with a stepped portion for engaging the outer fastening portion and the restraining bolt in the rotational direction to prevent the restraining bolt from rotating. In this case, it can suppress that a restraint bolt rotates together at the time of fastening of an inner side fastening part.

According to one aspect of the present invention, interference between the restraint bolt and the end plate can be suppressed.

It is a schematic sectional drawing which shows the battery module which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 2nd Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 3rd Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 4th Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 5th Embodiment. FIG. 6A and FIG. 6B are schematic diagrams illustrating examples of stepped portions. It is a schematic sectional drawing which shows the battery module which concerns on 6th Embodiment. FIG. 8A is a schematic cross-sectional view showing a first modification of the sixth embodiment, and FIG. 8B is a schematic cross-sectional view showing a second modification of the sixth embodiment. It is a schematic sectional drawing which shows the 3rd modification of 6th Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 7th Embodiment. In the battery module which concerns on 7th Embodiment, it is a schematic sectional drawing of the state to which the elastic member was compressively deformed until it reached the allowable compression amount with respect to expansion of a battery cell. It is a graph which shows the relationship between the amount of compressive deformation of the elastic member in the battery module which concerns on 7th Embodiment, and a restraint load. It is a schematic sectional drawing which shows the battery module which concerns on 8th Embodiment. It is a schematic sectional drawing which shows the battery module which concerns on 9th Embodiment. FIG. 15A is a schematic sectional view showing a first modification of the seventh embodiment, and FIG. 15B is a schematic sectional view showing a second modification of the seventh embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are used for the same or corresponding elements, and duplicate descriptions are omitted.

FIG. 1 is a schematic cross-sectional view showing the battery module according to the first embodiment. As shown in the figure, the battery module 1A according to the first embodiment includes an array body 2 in which a plurality of battery cells 3 are arrayed, and a pair of

end plates

6 and 7 sandwiching the array body 2 in the array direction D. And a restraining member 8A for applying a restraining load to the array body 2 in the array direction D. The array body 2 further includes an elastic member 4 and a middle plate 5.

The battery cell 3 constituting the array 2 is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery. In the present embodiment, the array body 2 includes eight battery cells 3. Adjacent battery cells 3 are bonded with, for example, a double-sided tape. Each battery cell 3 may be arranged in a state of being held by a resin cell holder. A heat transfer plate may be disposed between adjacent battery cells 3.

Each battery cell 3 is formed by accommodating an electrode assembly and an electrolyte in a hollow case having a substantially rectangular parallelepiped shape, for example. A pair of electrode terminals (not shown) are provided apart from each other on the top surface of the case. One of the electrode terminals is a positive electrode terminal connected to the positive electrode of the electrode assembly, and the other of the electrode terminals is a negative electrode terminal connected to the negative electrode of the electrode assembly. The positive electrode terminal and the negative electrode terminal are arranged adjacent to each other. The adjacent positive electrode terminal and negative electrode terminal are connected to each other by a bus bar member. Thereby, the

adjacent battery cells

3 and 3 are electrically connected in series.

The elastic member 4 is used for the purpose of preventing damage to the battery cell 3, the

end plates

6 and 7, and the restraining member 8A due to restraining load when the battery cell 3 expands. The elastic member 4 is formed in a rectangular plate shape by, for example, urethane rubber sponge. The elastic members 4 are arranged unevenly on one side in the arrangement direction D in the array 2. In the present embodiment, the elastic member 4 is disposed at one end of the array body 2 in the array direction D. Examples of other forming materials of the elastic member 4 include ethylene propylene diene rubber (EPDM), chloroprene rubber, and silicon rubber. The elastic member 4 is not limited to rubber but may be a spring material or the like.

The middle plate 5 is, for example, a resin plate member. The middle plate 5 has a substantially rectangular plate shape corresponding to the shape of the battery cell 3 when viewed from the arrangement direction D, and the middle plate 5 is formed between the battery cell 3 and the elastic member 4 located on the most one side in the arrangement direction D. Arranged between. The middle plate 5 suppresses variation in load applied to each battery cell 3 from the elastic member 4. At the four corners of the middle plate 5, there are provided insertion holes 5a through which the restraint bolts 12 described later are inserted.

The

end plates

6 and 7 are, for example, metal plate members. As with the middle plate 5, the

end plates

6 and 7 have a substantially rectangular plate shape corresponding to the shape of the battery cell 3 when viewed from the arrangement direction D. One end plate 6 is disposed so as to contact the elastic member 4. The other end plate 7 is disposed so as to contact the battery cell 3 located on the most other side in the arrangement direction D. At the four corners of the

end plates

6 and 7,

insertion holes

6a and 7a for inserting the restraining bolts 12 are provided, respectively.

On the edge 6b of the end plate 6, a fixing piece 9 used for fixing to the outside (here, the casing 10) is provided. The fixed piece 9 projects from the edge 6 b of the end plate 6 at a substantially right angle to the end plate 6. The fixing piece 9 is provided with a plurality of insertion holes 9 a through which the fixing bolts 11 are inserted along the edge 6 b of the end plate 6. A similar fixing piece 9 is also provided on the edge 7 b of the end plate 7. The battery module 1 is fixed to the casing 10 by screwing the fixing bolts 11 passed through the insertion holes 9 a into the bolt holes 10 a provided in the casing 10.

The restraining member 8 A includes a restraining bolt 12, an inner fastening portion 13, and an outer fastening portion 14. The restraint bolt 12 is a long bolt having a head portion 12a, and a screw portion 12b is formed at the tip. The threaded portion 12b is a portion of the restraint bolt 12 where a screw thread is provided to which the inner fastening portion 13 and the outer fastening portion 14 are screwed together. The restraint bolt 12 is stretched between the pair of

end plates

6 and 7 and connects the

end plates

6 and 7 to each other. The restraining member 8 A includes a restraining bolt 12 that connects the pair of

end plates

6, 7 at a position near the fixing piece 9, and a restraining bolt 12 that connects the pair of

end plates

6, 7 at a position away from the fixing piece 9. 2 each.

The restraint bolt 12 is passed through the

insertion holes

5a, 6a, and 7a so that the middle plate 5 and the

end plates

6 and 7 are inserted from the end plate 7 side. An outer fastening portion 14 formed of a hexagonal nut is screwed to the screw portion 12b of the restraint bolt 12 protruding from the end plate 6. The outer fastening portion 14 fastens the end plate 6 from the outside in the arrangement direction D, and sandwiches the pair of

end plates

6 and 7 between the head 12 a of the restraining bolt 12. As a result, the battery cell 3, the elastic member 4 and the middle plate 5 are sandwiched and unitized, and a predetermined restraining load is applied to the battery cell 3, the elastic member 4 and the middle plate 5 via the

end plates

6 and 7. Has been. This restraining load is balanced with the elastic repulsion force of the elastic member 4 and is, for example, about several hundred N.

Furthermore, an inner fastening portion 13 constituted by a nut having the same shape as the outer fastening portion 14 is screwed into the threaded portion 12b of the restraint bolt 12. The inner fastening portion 13 fastens the end plate 6 from the inner side in the arrangement direction D, and sandwiches the end plate 6 with the outer fastening portion 14 at the coupling position P of the restraint bolt 12. The coupling position P of the restraint bolt 12 is a position corresponding to the restraint bolt 12 in the end plate 6, and more specifically, is a peripheral portion of the insertion hole 6a. A large axial force acts on the end plate 6 by being tightened from both sides by the fastening force of the inner fastening portion 13 and the outer fastening portion 14. This axial force is larger than the restraining load, for example, about several thousand N. In addition, the shape of the inner side fastening part 13 and the outer side fastening part 14 is not restricted to hexagonal shape, Other shapes, such as circular shape, may be sufficient.

Next, an example of the assembly process of the battery module 1A will be described. First, the plurality of battery cells 3, the elastic member 4, the middle plate 5, and the end plate 7 are arranged along the arrangement direction D, and the restraint bolts 12 are inserted into the middle plate 5 and the end plate 7 from the end plate 7 side. Subsequently, the inner fastening portion 13 is screwed into the screw portion 12 b of the restraining bolt 12. At this time, the inner fastening portion 13 is positioned at a position inside the assembly position of the end plate 6 and outside the assembly position of the middle plate 5 so as not to hinder the work in a subsequent process.

Subsequently, the end plate 6 is disposed outside the elastic member 4 and the restraint bolt 12 is inserted through the end plate 6. Subsequently, the outer fastening portion 14 is screwed into the screw portion 12 b of the restraint bolt 12, and a predetermined restraint load is applied to the battery cell 3, the elastic member 4, and the middle plate 5. Subsequently, by rotating the inner fastening portion 13 and moving it toward the outside in the arrangement direction D, the end plate 6 is fastened from both sides by the inner fastening portion 13 and the outer fastening portion 14, and a predetermined axial force is applied to the end plate 6. Act. Thus, the battery module 1A is manufactured. In order to improve assemblability, the clearance between the

insertion holes

6a and 7a of the

end plates

6 and 7 and the shaft portion of the restraining bolt 12 is the clearance between the insertion hole 5a of the middle plate 5 and the shaft portion of the restraining bolt 12. It is larger than the clearance between.

As described above, in the battery module 1A of the present embodiment, the end plate 6 is fastened from both sides by the inner fastening portion 13 and the outer fastening portion 14 at the coupling position P of the restraint bolt 12, and the inner fastening portion 13 and the outer fastening portion 14 are secured. The restraint bolt 12 can be firmly fixed to the end plate 6 by generating a large axial force (fastening force) therebetween. For this reason, interference with the restraint bolt 12 and the end plate 6 can be suppressed. Furthermore, in the battery module 1A, the elastic bolt 4 is unevenly arranged in the pair of

end plates

6 and 7, and therefore, the restraining bolt 12 with respect to the end plate 6 that easily interferes with the restraining bolt 12. To fix. For this reason, interference with the restraint bolt 12 and the end plate 6 can be suppressed effectively.

Further, in the battery module 1A, the inner fastening portion 13 is configured by a nut screwed into the screw portion 12b of the restraint bolt 12. For this reason, a structure can be simplified. Further, in the battery module 1, the outer fastening portion 14 is configured by a nut that is screwed into the screw portion 12 b of the restraining bolt 12. For this reason, the configuration can be further simplified.

As mentioned above, although one embodiment of the present invention was described, the present invention is not limited to the above embodiment. For example, the battery module may be configured like the battery module 1B of the second embodiment shown in FIG. In the restraining member 8B of the second embodiment, the restraining bolt 12 is a stepped bolt in which a screw portion 12d having a smaller diameter than the cylindrical portion 12c is provided on the distal end side of the cylindrical portion 12c. The inner fastening portion 13 is constituted by a step portion 12e between the cylindrical portion 12c and the screw portion 12d. The step portion 12e has, for example, a step surface perpendicular to the arrangement direction D. Such a constraining bolt 12 is formed, for example, by scraping the tip portion of a cylindrical base material and providing a screw portion 12d at the tip portion. A screw portion 12f is provided on the proximal end side of the cylindrical portion 12c, and a double nut 15 is screwed to the screw portion 12f. In the second embodiment, a pair of

end plates

6 and 7 are sandwiched between the outer fastening portion 14 and the double nut 15. Further, the end plate 6 is sandwiched between the stepped portion 12e (inner fastening portion 13) and the outer fastening portion 14. A normal nut may be used in place of the double nut 15, but the use of the double nut 15 can prevent loosening when the elastic member 4 contracts.

In the assembly process of the battery module 1B of the second embodiment, first, after the restraint bolt 12 is inserted through the end plate 6, the outer fastening portion 14 is screwed into the screw portion 12b of the restraint bolt 12, and the end plate 6 is attached. The inner fastening portion 13 (step 12e) and the outer fastening portion 14 are tightened from both sides. Subsequently, the plurality of battery cells 3, the elastic member 4, the middle plate 5, and the end plate 6 are arranged along the arrangement direction D, and the restraint bolts 12 are inserted into the middle plate 5 and the end plate 7 from the end plate 6 side. . Subsequently, a double nut 15 is screwed into the screw portion 12 f of the restraint bolt 12, and a predetermined restraint load is applied to the battery cell 3, the elastic member 4, and the middle plate 5. Thus, the battery module 1B is manufactured.

Also in the second embodiment, similarly to the first embodiment, the restraint bolt 12 can be firmly fixed to the end plate 6 and interference between the restraint bolt 12 and the end plate 6 can be suppressed. Moreover, in 2nd Embodiment, the restraint volt | bolt 12 is a stepped volt | bolt by which the screw part 12d smaller diameter than the said cylindrical part 12c was provided in the front end side of the cylindrical part 12c, and the inner side fastening part 13 is the cylindrical part 12c. Since the step portion 12e is between the screw portion 12d and the screw portion 12d, the number of parts can be reduced.

The battery module may be configured like a battery module 1C of the third embodiment shown in FIG. In the restraining member 8 C of the third embodiment, the inner fastening portion 13 is configured by a flange portion 12 g provided on the restraining bolt 12. The flange portion 12g has an annular shape, for example, and is coupled to one end portion side of the restraint bolt 12 by welding or the like. Similarly to the second embodiment, a double nut 15 is screwed to a screw portion 12f provided on the other end side of the restraining bolt 12, and a pair of end plates is provided between the outer fastening portion 14 and the double nut 15. 6 and 7 are sandwiched. Further, the end plate 6 is sandwiched between the flange portion 12g (inner fastening portion 13) and the outer fastening portion 14. The battery module 1C of the third embodiment is manufactured by the same assembly process as that of the second embodiment.

Also in the third embodiment, similarly to the first embodiment, the restraint bolt 12 can be firmly fixed to the end plate 6, and interference between the restraint bolt 12 and the end plate 6 can be suppressed. Moreover, in 3rd Embodiment, since it is comprised by the collar part 12g provided in the restraint volt | bolt 12, the number of parts can be reduced. Moreover, the area of the contact surface of the inner side fastening part 13 and the end plate 6 is easily securable by changing the diameter of the collar part 12g.

The battery module may be configured as a battery module 1D of the fourth embodiment shown in FIG. In the restraining member 8 D of the fourth embodiment, the outer fastening portion 14 is configured by the head 12 h of the restraining bolt 12. A screw portion 12 i into which the inner fastening portion 13 is screwed is provided at a portion adjacent to the head portion 12 h in the restraint bolt 12. Similar to the second and third embodiments, the double nut 15 is screwed to the screw portion 12f provided on the opposite side of the head 12h of the restraining bolt 12, and the outer fastening portion 14 and the double nut 15 are connected to each other. A pair of

end plates

6 and 7 are sandwiched between them. Further, the end plate 6 is sandwiched between the inner fastening portion 13 and the head portion 12h (outer fastening portion 14). The inner side fastening part 13 is comprised with the nut similarly to 1st Embodiment. The restraint bolt 12 is inserted through the middle plate 5 and the end plate 7 from the end plate 6 side. In the assembly process of the battery module 1D of the fourth embodiment, first, after the restraint bolt 12 is inserted through the end plate 6, the inner fastening portion 13 is screwed into the threaded portion 12i of the restraint bolt 12, and the end plate 6 is attached. Tighten from both sides by the inner fastening part 13 and the outer fastening part 14 (head 12h). The other points are the same as in the second embodiment.

Also in the fourth embodiment, similarly to the first embodiment, the restraint bolt 12 can be firmly fixed to the end plate 6, and interference between the restraint bolt 12 and the end plate 6 can be suppressed. Further, in the fourth embodiment, since the outer fastening portion 14 is configured by the head 12h of the restraining bolt 12, the configuration can be simplified and the number of parts can be reduced.

The battery module may be configured like a battery module 1E of the fifth embodiment shown in FIGS. 5 and 6A. In the fifth embodiment, in the third embodiment, a step portion 16 for engaging the inner surface 6c of the end plate 6 in the rotational direction of the inner fastening portion 13 and the restraining bolt 12 to prevent the restraining bolt 12 from rotating. Is provided. In this example, by providing the protruding portion 17 protruding from the surface 6 c of the end plate 6, a step portion 16 is formed between the surface 6 c and the protruding portion 17. In the restraining member 8E of the fifth embodiment, the collar portion 12g has a hexagonal shape as viewed from the arrangement direction D, as shown in FIG. The protrusions 17 have a rectangular shape when viewed from the arrangement direction D, and a pair of protrusions 17 are provided around each flange 12g so as to sandwich the flange 12g. The pair of protrusions 17 facing each other with the flange 12g interposed therebetween are arranged in parallel to each other, and the distance between the pair of protrusions 17 is equal to or more than the distance between the two opposite surfaces of the flange 12g. Slightly larger. At the time of assembly, the inner fastening portion 13 is disposed between the pair of projecting portions 17 (step portions 16), and the inner fastening portion 13 and the projecting portion 17 are engaged in the rotation direction of the restraint bolt 12. Thereby, it can suppress that the restraint volt | bolt 12 turns together at the time of the fastening of the outer side fastening part 14 (circulation).

In the fifth embodiment, as shown in FIG. 6B, the pair of projecting portions 17 are provided with the projecting portions 17a projecting in the opposite directions, and the recessed portions 12j into which the projecting portions 17a enter the flange portions 12g. May be provided. In this case, the protrusion 17a and the recess 12j are engaged in the rotational direction of the restraint bolt 12, so that the rotation of the restraint bolt 12 when the outer fastening portion 14 is fastened can be further suppressed. In the fifth embodiment, the step portion 16 is formed by the provision of the protruding portion 17 protruding from the surface 6c of the end plate 6. However, the step portion 16 is a recess in which the inner fastening portion 13 enters the surface 6c of the end plate 6. May be formed. A step 16 may be added to the second embodiment. In the fourth embodiment, the outer surface of the end plate 6 is provided with a stepped portion for engaging the outer fastening portion 14 (head 12h) and the restraining bolt 12 in the rotational direction to prevent the restraining bolt 12 from rotating. May be. Also in this case, the stepped portion may be formed by providing a protruding portion that protrudes from the outer surface of the end plate 6, or a recess in which the outer fastening portion 14 enters the outer surface of the end plate 6. It may be formed by being provided. In 5th Embodiment, the inner side fastening part 13 may be comprised by the nut screwed together by the thread part 12d. In this case, for example, the inner fastening portion 13 is positioned by being screwed to the screwing limit of the screw portion 12d (abut against the end portion of the screw portion 12d). About the assembly process, after positioning the inner side fastening part 13, the assembly procedure similar to 2nd Embodiment is employable. In 4th Embodiment, the outer side fastening part 14 is comprised by the nut screwed by the screw part provided in the front-end | tip part of the restraint volt | bolt 12, and an outer side fastening part (nut) is formed in the outer surface of the end plate 6. FIG. ) And a stepped portion for preventing the restraint bolt 12 from rotating by engaging in the rotational direction of the restraint bolt 12. In this case, the outer fastening portion 14 is positioned by being screwed to the screwing limit of the screw portion, for example. This screw portion is provided separately from the screw portion 12i.

In the first embodiment, the elastic member 4 is disposed at one end of the array direction D in the array body 2. However, it is sufficient that the elastic member 4 is unevenly disposed on one side of the array direction D in the array body 2. You may arrange | position between the battery cells 3 adjacent on the one end side. The number and arrangement of the elastic members 4 are not limited. For example, a plurality of elastic members 4 may be arranged between the arrangement ends of the array 2 and / or between the battery cells 3. In the first embodiment, after the outer fastening portion 14 is fastened, the inner fastening portion 13 and / or the outer fastening portion 14 and the end plate 6 may be joined by welding. In this case, the restraint bolt 12 can be more firmly fixed to the end plate 6.

Subsequently, another aspect of the present invention will be described.
The conventional battery module includes an array body in which a plurality of battery cells are arrayed, a pair of end plates that sandwich the array body in the array direction of the battery cells, and a restraint that applies a restraining load to the array body in the array direction. And a member. The restraining member includes a restraining bolt inserted into an insertion hole provided in each end plate, and a pair of nuts screwed to the projecting portions of the restraining bolt projecting outward from each end plate. The restraint load is applied to the array by tightening the pair of end plates from the outside with these nuts.

In the battery module as described above, for example, when an impact load is applied due to vibration of a vehicle to be mounted, the position of the restraint bolt in the insertion hole may vary. When the position of the restraint bolt changes, the restraint bolt interferes with the end plate, and an excessive load may be applied to the restraint bolt at the interference position. In order to suppress the occurrence of such a situation, an inner fastening portion that tightens one end plate from the inside and an outer fastening portion that fastens from the outside are added at the binding position of the restraint bolt, and the restraint bolt and the end plate are firmly fixed. It is possible to do. However, when such a configuration is adopted, when the battery cell expands in the arrangement direction due to deterioration or overcharge, an excessive load is applied to the outer fastening portion via the end plate, and the contact surface with the end plate in the outer fastening portion There is a risk of problems such as sinking.

An aspect of the present invention has been made to solve the above problems, and an object thereof is to provide a highly reliable battery module.

A battery module according to an aspect of the present invention includes an array formed by arranging a plurality of battery cells, a pair of end plates that sandwich the array in the array direction of the battery cells, and a constraint that connects the pair of end plates together. A restraint member having a bolt and applying a restraint load to the array body in the array direction, and the restraint member tightens one end plate from the inside at the coupling position of the restraint bolt and tightens from the outside. Including the outer fastening portion, the strength of the outer fastening portion with respect to the load in the arrangement direction is higher than the strength of the inner fastening portion with respect to the load in the arrangement direction.

In this battery module, the end plate on one side is tightened from both sides by the inner fastening portion and the outer fastening portion at the binding position of the restraint bolt, and a large axial force (fastening force) is generated between the both fastening portions. It is possible to firmly fix the restraint bolt. For this reason, interference with a restraint volt | bolt and an end plate can be suppressed. Furthermore, in this battery module, the strength of the outer fastening portion with respect to the load in the arrangement direction is higher than the strength of the inner fastening portion with respect to the load in the arrangement direction. Thereby, the intensity | strength of an outer side fastening part can be ensured, and even when a battery cell expand | swells and a comparatively big load is applied to an outer side fastening part, it can suppress that a malfunction arises in an outer side fastening part. Therefore, according to this battery module, reliability can be improved.

The area of the contact surface between the outer fastening portion and one end plate may be larger than the area of the contact surface between the inner fastening portion and one end plate. In this case, the strength of the outer fastening portion can be ensured by making the area of the contact surface between the outer fastening portion and the one end plate larger than the area of the contact surface between the inner fastening portion and the one end plate.

The hardness of the outer fastening portion may be higher than the hardness of the inner fastening portion. In this case, the strength of the outer fastening portion can be ensured by making the hardness of the outer fastening portion higher than the hardness of the inner fastening portion.

Fixing pieces used for fixing to the outside are respectively provided at the edges of the pair of end plates, and the restraining member is fixed to a first restraining bolt that connects the pair of end plates at a position closer to the fixing piece. A second restraint bolt that couples the pair of end plates at a position away from the piece, and the strength against the load in the arrangement direction of the outer fastening portion at the joining position of the second restraint bolt is the first restraint. You may be higher than the intensity | strength with respect to the load of the arrangement direction of the outer side fastening part in the coupling | bonding position of a volt | bolt. When the end plate is fixed to the outside with a fixing piece provided at the edge, when the battery cell expands, the coupling position of the first restraining bolt that connects the pair of end plates at a position closer to the fixing piece There is a tendency that the load applied to the outer fastening portion at the coupling position of the second restraint bolt that connects the pair of end plates at a position distant from the fixed piece is larger than the load applied to the outer fastening portion in FIG. In this battery module, the strength against the load in the arrangement direction of the outer fastening portion at the coupling position of the second restraining bolt is higher than the strength against the load in the arrangement direction of the outer fastening portion at the coupling position of the first restraint bolt. Yes. Thereby, it can suppress suitably that a malfunction arises in the outer side fastening part in the joint position of the 2nd restraint bolt.

According to one aspect of the present invention, a highly reliable battery module can be provided.

FIG. 7 is a schematic cross-sectional view showing the battery module according to the sixth embodiment. As shown in the figure, the battery module 101 according to the sixth embodiment includes an array body 102 in which a plurality of battery cells 103 are arrayed, and a pair of

end plates

106 and 107 that sandwich the array body 102 in the array direction D. , And a restraining member 108 that applies a restraining load in the arrangement direction D to the array body 102. The array 102 further includes an elastic member 104 and a middle plate 105.

The battery cell 103 constituting the array 102 is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery. In the sixth embodiment, the array body 102 includes eight battery cells 103. Adjacent battery cells 103 are bonded with, for example, a double-sided tape. Each battery cell 103 may be arranged in a state of being held by a resin cell holder. A heat transfer plate may be disposed between adjacent battery cells 103.

Each battery cell 103 is formed by, for example, housing an electrode assembly and an electrolytic solution in a hollow case having a substantially rectangular parallelepiped shape. A pair of electrode terminals (not shown) are provided apart from each other on the top surface of the case. One of the electrode terminals is a positive electrode terminal connected to the positive electrode of the electrode assembly, and the other of the electrode terminals is a negative electrode terminal connected to the negative electrode of the electrode assembly. The positive electrode terminal and the negative electrode terminal are arranged adjacent to each other. The adjacent positive electrode terminal and negative electrode terminal are connected to each other by a bus bar member. Thereby, the

adjacent battery cells

103 and 103 are electrically connected in series.

The elastic member 104 is used for the purpose of preventing the battery cell 103, the

end plates

106 and 107, and the restraining member 108 from being damaged by the restraining load when the battery cell 103 expands. The elastic member 104 is formed in a rectangular plate shape by, for example, urethane rubber sponge. The elastic member 104 is disposed at one end of the array body 102 in the array direction D. Examples of other forming materials of the elastic member 104 include ethylene propylene diene rubber (EPDM), chloroprene rubber, and silicon rubber. Further, the elastic member 104 is not limited to rubber but may be a spring material or the like.

The middle plate 105 is, for example, a resin plate member. The middle plate 105 has a substantially rectangular plate shape corresponding to the shape of the battery cell 103 when viewed from the arrangement direction D, and the middle plate 105 is formed between the battery cell 103 located on the most one side in the arrangement direction D and the elastic member 104. Arranged between. The middle plate 105 suppresses variation in load applied to each battery cell 103 from the elastic member 104. At the four corners of the middle plate 105, there are provided insertion holes 105a through which the restraining bolts 112 described later are inserted.

The

end plates

106 and 107 are, for example, metal plate members. Similar to the middle plate 105, the

end plates

106 and 107 have a substantially rectangular plate shape corresponding to the shape of the battery cell 103 when viewed from the arrangement direction D. One end plate 106 is disposed so as to contact the elastic member 104. The other end plate 107 is disposed so as to contact the battery cell 103 located on the most other side in the arrangement direction D. At the four corners of the

end plates

106 and 107,

insertion holes

106a and 107a through which the restricting bolts 112 are inserted are provided, respectively.

On the edge portion 106b of the end plate 106, a fixing piece 109 used for fixing to the outside (here, the casing 110) is provided. The fixed piece 109 projects from the edge portion 106 b of the end plate 106 at a substantially right angle to the end plate 106. The fixing piece 109 is provided with a plurality of insertion holes 109 a through which the fixing bolts 111 are inserted along the edge portion 106 b of the end plate 106. A similar fixing piece 109 is also provided at the edge 107 b of the end plate 107. The battery module 101 is fixed to the casing 110 by screwing the fixing bolts 111 passed through the insertion holes 109 a into the bolt holes 110 a provided in the casing 110.

The restraining member 108 includes a restraining bolt 112, an inner fastening portion 113, and an outer fastening portion 114. The restraint bolt 112 is a long bolt having a head portion 112a, and a screw portion 112b is formed at the tip. The restraint bolt 112 is stretched between the pair of

end plates

106 and 107, and connects the

end plates

106 and 107 to each other. The restraining member 108 includes, as restraining bolts 112, a first restraining bolt 112 A that connects the pair of

end plates

106, 107 at a position near the fixing piece 109, and a pair of end plates 106, There are two second restraining bolts 112B for connecting the two 107 together.

The restraint bolt 112 is passed through the

insertion holes

105a, 106a, 107a so as to pass through the middle plate 105 and the

end plates

106, 107 from the end plate 107 side. An outer fastening portion 114 made of a nut is screwed to the screw portion 112b of the restraining bolt 112 protruding from the end plate 106. The outer fastening portion 114 fastens the end plate 106 from the outside in the arrangement direction D, and sandwiches the pair of

end plates

106 and 107 between the head 112 a of the restraining bolt 112. As a result, the battery cell 103, the elastic member 104 and the middle plate 105 are sandwiched and unitized, and a predetermined restraining load is applied to the battery cell 103, the elastic member 104 and the middle plate 105 via the

end plates

106 and 107. Has been. This restraining load is balanced with the elastic repulsive force of the elastic member 104, and is about several hundred N, for example.

Furthermore, an inner fastening portion 113 made of a nut is screwed to the screw portion 112b of the restraining bolt 112. The inner fastening portion 113 fastens the end plate 106 from the inner side in the arrangement direction D, and sandwiches the end plate 106 with the outer fastening portion 114 at the coupling position P of the restraint bolt 112. The coupling position P of the restraint bolt 112 is a position corresponding to the restraint bolt 112 in the end plate 106, and more specifically, is a peripheral portion of the insertion hole 106a. A large axial force acts on the end plate 106 by being tightened from both sides by the fastening force of the inner fastening portion 113 and the outer fastening portion 114. This axial force is larger than the restraining load, for example, about several thousand N.

The inner fastening portion 113 includes an inner fastening portion 113A at the coupling position P of the first restraining bolt 112A and an inner fastening portion 113B at the coupling position P of the second restraining bolt 112B. The outer fastening portion 114 includes an outer fastening portion 114A at the coupling position P of the first restraining bolt 112A and an outer fastening portion 114B at the coupling position P of the second restraining bolt 112B. The inner fastening portion 113 and the outer fastening portion 114 have similar outer shapes when viewed from the arrangement direction D. In this example, the outer shape of the inner fastening portion 113 and the outer fastening portion 114 when viewed from the arrangement direction D is a hexagonal shape. In 6th Embodiment, the inner side fastening part 113 and the outer side fastening part 114 are comprised with the mutually same material. The inner fastening portion 113 and the outer fastening portion 114 have the same thickness.

In the battery module 101, with respect to the inner fastening portion 113A and the outer fastening portion 114A at the coupling position P of the first restraining bolt 112A, the two-side width (distance between two opposite side surfaces) D1 of the outer fastening portion 114A is the inner fastening. By being wider than the two-surface width D2 of the portion 113A, the area of the seating surface (contact surface with the end plate 106) of the outer fastening portion 114A is larger than the area of the seating surface of the inner fastening portion 113A. . Thereby, the strength with respect to the load in the arrangement direction D of the outer fastening portion 114A is higher than the strength with respect to the load in the arrangement direction D of the inner fastening portion 113A.

Similarly, for the inner fastening portion 113B and the outer fastening portion 114B at the coupling position P of the second restraining bolt 112B, the two-sided width (distance between two opposing side surfaces) D3 of the outer fastening portion 114B is the inner fastening portion 113B. By being wider than the two-surface width D2, the area of the seating surface of the outer fastening portion 114B is larger than the area of the seating surface of the inner fastening portion 113B. Thereby, the strength with respect to the load in the arrangement direction D of the outer fastening portion 114B is higher than the strength with respect to the load in the arrangement direction D of the inner fastening portion 113B. The two-sided width of the inner fastening portion 113B is equal to the two-sided width D2 of the inner fastening portion 113A.

Further, since the two-surface width D3 of the outer fastening portion 114B is wider than the two-surface width D1 of the outer fastening portion 114A, the area of the seating surface of the outer fastening portion 114B is larger than the area of the seating surface of the outer fastening portion 114A. Is also getting wider. Thereby, the strength with respect to the load in the arrangement direction D of the outer fastening portion 114B is higher than the strength with respect to the load in the arrangement direction D of the outer fastening portion 114A. In addition, not only the width across flats, but the strength relationship as described above may be realized by changing the diagonal distance, for example. For example, when the outer shape of the inner fastening portion 113 and the outer fastening portion 114 when viewed from the arrangement direction D is circular, the strength relationship as described above may be realized by changing the diameter. Thus, the external shape of the inner side fastening part 113 and the outer side fastening part 114 when viewed from the arrangement direction D is not limited, and may be any shape.

The area of the seating surface of the inner fastening portion 113 is set so that the seating surface does not sink due to the initial fastening force (axial force of the restraining bolt 112) applied when the battery module 101 is assembled. More specifically, for example, the following equation is set. Bearing surface depression stress [Pa] of the inner fastening portion 113> initial fastening force [N] / seat surface area of the inner fastening portion 113 [m ² ] Here, the seating surface depression stress depends on the material constituting the inner fastening portion 113. It is a determined value. The initial fastening force is larger than the sliding direction load applied to the seating surface of the inner fastening portion 113 by vibration or impact. That is, the initial fastening force satisfies the following formula. Initial fastening force [N] x bearing friction coefficient> sliding direction load [N]

Regarding the outer fastening portion 114, when the battery cell 103 expands in the arrangement direction D due to deterioration or overcharge, a load is applied to the end plate 106 from the elastic member 104 that is compressed and deformed, and the outer fastening portion 114 is interposed via the end plate 106. A large load is applied. Therefore, the area of the seating surface of the outer fastening portion 114 is set wider than the area of the seating surface of the inner fastening portion 113 so that the seating surface does not collapse even when the load is applied in addition to the initial fastening force. .

In particular, as in the sixth embodiment, when the

end plates

106 and 107 are fixed to the casing 110 by the fixing pieces 109 provided on the edges 106b and 107b, when the battery cell 103 expands, the

end plates

106 and 107 are closer to the fixing pieces 109. The pair of

end plates

106 and 107 are located at a position farther from the fixed piece 109 than the load applied to the outer fastening portion 114A at the coupling position P of the first restraining bolt 112A that couples the pair of

end plates

106 and 107 at the position. There is a tendency that the load applied to the outer fastening portion 114B at the coupling position P of the second restraining bolt 112B connecting the two is increased. This is because the

end plates

106 and 107 are fixed to the housing 110 on the fixed piece 109 side, and the

end plates

106 and 107 have high rigidity in the portion near the fixed piece 109 in the

end plates

106 and 107. This is because the end portion on the side farther from the fixing piece 109 in this case tends to be deformed so that the second constraining bolt 112B extends. Therefore, in the battery module 101, the area of the seating surface of the outer fastening portion 114B is set wider than the area of the seating surface of the outer fastening portion 114A.

Next, an example of the assembly process of the battery module 101 will be described. First, the plurality of battery cells 103, the elastic member 104, the middle plate 105, and the end plate 107 are arranged along the arrangement direction D, and the restraining bolts 112 are inserted into the middle plate 105 and the end plate 107 from the end plate 107 side. Subsequently, the inner fastening portion 113 is screwed into the screw portion 112 b of the restraining bolt 112. At this time, the inner fastening portion 113 is positioned inside the assembly position of the end plate 106 and outside the assembly position of the middle plate 105 so as not to hinder work in a subsequent process.

Subsequently, the end plate 106 is disposed so as to be adjacent to the elastic member 104, and the restraint bolt 112 is inserted through the end plate 106. Subsequently, the outer fastening portion 114 is screwed into the threaded portion 112 b of the restraining bolt 112, and a predetermined restraining load is applied to the battery cell 103, the elastic member 104, and the middle plate 105. Subsequently, the inner fastening portion 113 is rotated and moved toward the outer side in the arrangement direction D, whereby the end plate 106 is fastened from both sides by the inner fastening portion 113 and the outer fastening portion 114, and a predetermined axial force is applied to the end plate 106. Act. Thus, the battery module 101 is manufactured. In order to improve the assemblability, the clearance between the

insertion holes

106a and 107a of the

end plates

106 and 107 and the shaft portion of the restraining bolt 112 is the same as the clearance between the insertion hole 105a of the middle plate 105 and the shaft portion of the restraining bolt 112. The clearance between is larger.

As described above, in the battery module 101 of the sixth embodiment, the end plate 106 is fastened from both sides by the inner fastening portion 113 and the outer fastening portion 114 at the coupling position P of the restraint bolt 112, and the inner fastening portion 113 and the outer fastening portion are tightened. By generating a large axial force (fastening force) with the end plate 106, the restraint bolt can be firmly fixed to the end plate 106. For this reason, interference with the restraint bolt 112 and the end plate 106 can be suppressed. Further, in the battery module 101, the strength of the outer fastening portion 114 with respect to the load in the arrangement direction D is higher than the strength of the inner fastening portion 113 with respect to the load in the arrangement direction D. Thereby, the intensity | strength of the outer side fastening part 114 can be ensured, and even when the battery cell 103 expand | swells and a comparatively big load is applied to the outer side fastening part 114, it can suppress that a malfunction arises in the outer side fastening part 114. FIG. Therefore, according to the battery module 101, reliability can be improved.

In the battery module 101, the area of the contact surface between the outer fastening portion 114 and the end plate 106 is larger than the area of the contact surface between the inner fastening portion 113 and the end plate 106. Thereby, the strength of the outer fastening portion 114 can be ensured by making the area of the contact surface between the outer fastening portion 114 and the end plate 106 larger than the area of the contact surface between the inner fastening portion 113 and the end plate 106.

In the battery module 101, the strength against the load in the arrangement direction D of the outer fastening portion 114B at the joining position P of the second restraining bolt 112B is such that the strength of the outer fastening portion 114A in the joining position P of the first restraining bolt 112A is It is higher than the strength against the load of D. Thereby, it can suppress suitably that a malfunction arises in the outer side fastening part 114B in the joint position P of the 2nd restraint bolt 112B.

Although the sixth embodiment of the present invention has been described above, the present invention is not limited to the sixth embodiment. For example, the sixth embodiment may be configured as a first modified example shown in FIG. In the first modification, the restraint bolt 112 is a stepped bolt in which a screw portion 112d having a smaller diameter than the cylindrical portion 112c is provided on the tip side of the cylindrical portion 112c, and the inner fastening portion 113 is connected to the cylindrical portion 112c and the screw. It is comprised by the level | step-difference part 112e between the parts 112d. The step portion 112e has a step surface perpendicular to the arrangement direction D, for example. Such a constraining bolt 112 is formed, for example, by cutting out the tip portion of a cylindrical base material and providing a screw portion 112d at the tip portion. A screw portion is provided on the proximal end side of the cylindrical portion 112c, and, for example, a double nut is screwed to the screw portion. In this example, a pair of

end plates

106 and 107 are sandwiched between the outer fastening portion 114 and the double nut. Further, the end plate 106 is sandwiched between the stepped portion 112e (inner fastening portion 113) and the outer fastening portion 114. The relationship of the strength with respect to the load in the arrangement direction D of the inner fastening portions 113A and 13B and the

outer fastening portions

114A and 114B is the same as that in the sixth embodiment.

In the assembly process of the first modified example, first, after the constraining bolt 112 is inserted through the end plate 106, the outer fastening part 114 is screwed into the threaded part 112 b of the restraining bolt 112, and the end plate 106 is joined to the inner fastening part 113. Fastening is performed from both sides by the (step portion 112e) and the outer fastening portion 114. Subsequently, the plurality of battery cells 103, the elastic member 104, the middle plate 105, and the end plate 106 are arranged along the arrangement direction D, and the restraining bolts 112 are inserted into the middle plate 105 and the end plate 107 from the end plate 106 side. . Subsequently, a double nut is screwed into the screw portion on the proximal end side of the restraint bolt 112, and a predetermined restraint load is applied to the battery cell 103, the elastic member 104, and the middle plate 105. As described above, the battery module 101 of the first modification is manufactured. According to such a first modified example, as in the sixth embodiment, it is possible to suppress interference between the restraining bolt 112 and the end plate 106 and to prevent the outer fastening portion 114 from being defective.

6th Embodiment may be comprised like the 2nd modification shown by FIG.8 (b). In the second modification, the inner fastening portion 113 is constituted by a flange portion 112 f provided on the restraining bolt 112. The flange portion 112f has an annular shape, for example, and is coupled to one end side of the restraint bolt 112 by welding or the like. Similar to the first modified example, a double nut is screwed to a screw portion provided on the other end side of the restraining bolt 112, and a pair of end plates 106, between the outer fastening portion 114 and the double nut, 107 is sandwiched. Further, the end plate 106 is sandwiched between the flange portion 112f (inner fastening portion 113) and the outer fastening portion 114. The relationship between the strength of the

inner fastening portions

113A and 113B and the

outer fastening portions

114A and 114B with respect to the load in the arrangement direction D is the same as that in the sixth embodiment. The battery module 101 of the second modification is manufactured by the same assembly process as that of the first modification. According to such a second modified example, as in the sixth embodiment, interference between the restraining bolt 112 and the end plate 106 can be suppressed, and occurrence of a problem in the outer fastening portion 114 can be suppressed.

The sixth embodiment may be configured as a third modified example shown in FIG. In the third modification, the outer fastening portion 114 is configured by the head portion 112g of the restraining bolt 112. A screw portion 112h into which the inner fastening portion 113 is screwed is provided at a portion adjacent to the head portion 112g in the restraint bolt 112. Similar to the first and second modified examples, a double nut is screwed to a screw portion provided on the base end side (the side opposite to the head portion 112g) of the restraining bolt 112, and the outer fastening portion 114 and the double fastening portion are connected. A pair of

end plates

106 and 107 are held between the nuts. Further, the end plate 106 is sandwiched between the inner fastening portion 113 and the head portion 112g (outer fastening portion 114). The relationship of the strength with respect to the load in the arrangement direction D of the

inner fastening portions

113A and 113B and the

outer fastening portions

114A and 114B is the same as that in the above embodiment. In the third modification, the restraining bolt 112 is inserted through the middle plate 105 and the end plate 107 from the end plate 106 side. In the assembly process of the third modified example, first, after the restraint bolt 112 is inserted into the end plate 106, the inner fastening portion 113 is screwed into the screw portion 112 h of the restraint bolt 112, and the end plate 106 is joined to the inner fastening portion 113. And it tightens from both sides by the outer side fastening part 114 (head 112g). Other points are the same as in the case of the first modification. According to such a third modified example, as in the sixth embodiment, interference between the restraining bolt 112 and the end plate 106 can be suppressed, and occurrence of a problem in the outer fastening portion 114 can be suppressed.

In the sixth embodiment, since the area of the seating surface of the outer fastening portion 114 is larger than the area of the seating surface of the inner fastening portion 113, the strength of the outer fastening portion 114 with respect to the load in the arrangement direction D is increased. The strength of the outer fastening portion 114 is higher than the strength of the inner fastening portion 113 instead of or in addition to the strength of the 113 in the arrangement direction D. It may be realized. For example, the hardness of the outer fastening portion 114 may be made higher than the hardness of the inner fastening portion 113 by using a material having higher rigidity than the material constituting the inner fastening portion 113 as the material constituting the outer fastening portion 114. . As a combination of such materials, a combination of non-quenched steel (inner fastening portion 113) and hardened steel (outer fastening portion 114), aluminum (inner fastening portion 113) and steel (outer fastening portion 114). ) And the like. In the sixth embodiment, the number and arrangement of the elastic members 104 are not limited. For example, a plurality of elastic members 104 may be arranged between the arrangement end of the arrangement body 102 and / or each battery cell 103.

Subsequently, another aspect of the present invention will be described.
The conventional battery module includes an array formed by arranging a plurality of battery cells, an elastic member disposed at one end of the array in the array direction, and a battery cell positioned closest to the elastic member in the array. A middle plate disposed between the elastic member, a pair of end plates that sandwich the array in the array direction, and a restraining member that applies a restraining load in the array direction to the array. . The restraining member includes a restraining bolt inserted into an insertion hole provided in each end plate, and a pair of nuts screwed to the projecting portions of the restraining bolt projecting outward from each end plate. The restraint load is applied to the array by tightening the pair of end plates from the outside with these nuts.

In the battery module as described above, for example, when an impact load is applied due to vibration of a vehicle to be mounted, the position of the restraint bolt in the insertion hole may vary. When the position of the restraint bolt changes, the restraint bolt interferes with the end plate, and an excessive load may be applied to the restraint bolt at the interference position. In order to suppress the occurrence of such a situation, an inner fastening part for fastening the end plate on the elastic member side from the inside and an outer fastening part for fastening from the outside are added at the binding position of the restraining bolt, thereby strengthening the restraining bolt and the end plate. It is possible to fix to. However, when such a configuration is adopted, when the battery cell expands in the arrangement direction due to deterioration or overcharge, the middle plate moved in the arrangement direction along with the compression deformation of the elastic member interferes with the inner fastening portion, and the middle plate May cause problems such as damage.

A battery module according to an aspect of the present invention includes an array formed by arranging a plurality of battery cells, an elastic member disposed at one end of the array in the array direction, and the array member positioned closest to the elastic member. A middle plate disposed between the battery cell and the elastic member, a pair of end plates sandwiching the array body in the array direction, and a restraining bolt that connects the pair of end plates to each other. A restraining member that applies a restraining load in the arrangement direction, and the restraining member includes an inner fastening portion that fastens the end plate on the elastic member side from the inside and an outer fastening portion that fastens from the outside at the binding position of the restraining bolt, The elastic member is pressed between the middle plate and the end plate on the elastic member side until the allowable compression amount against the expansion of the battery cell is reached. Relief portion to form a gap between the middle plate and the inner fastening portions are provided when deformed.

In this battery module, the end plate on the elastic member side is fastened from both sides by the inner fastening portion and the outer fastening portion at the binding position of the restraint bolt, and a large axial force (fastening force) is generated between the two fastening portions. The restraint bolt can be firmly fixed to the plate. For this reason, interference with a restraint volt | bolt and an end plate can be suppressed. Further, in this battery module, when the elastic member is compressed and deformed until the allowable compression amount for expansion of the battery cell is reached between the middle plate and the end plate on the elastic member side at the binding position of the restraint bolt. An escape portion is provided to form a gap between the inner fastening portion and the inner fastening portion. Thereby, even when a battery cell expand | swells and an elastic member is compressed, it can suppress that a middle plate interferes with an inner side fastening part. Therefore, according to this battery module, reliability can be improved.

The escape portion may be configured by making the thickness of the inner fastening portion thinner than the thickness of the elastic member when it is compressed and deformed up to the allowable compression amount. In this case, it can suppress that a middle plate interferes with an inner side fastening part by simple structure.

The escape portion may be configured by disposing an inner fastening portion in a concave portion provided on a surface of the end plate on the elastic member side facing the middle plate. In this case, it is possible to reliably ensure a gap between the middle plate and the inner fastening portion when the elastic member is compressed and deformed until the allowable compression amount is reached.

The escape portion may be configured by providing a concave portion into which the inner fastening portion enters when the elastic member is compressed and deformed on a surface of the middle plate facing the end plate on the elastic member side. In this case, it is possible to reliably ensure a gap between the middle plate and the inner fastening portion when the elastic member is compressed and deformed until the allowable compression amount is reached.

Fixing pieces used for fixing to the outside are respectively provided at the edges of the pair of end plates, and the restraining member includes a first restraining bolt that connects the pair of end plates at a position closer to the fixing piece, A second restraint bolt that connects the pair of end plates at a position farther from the fixed piece than the one restraint bolt, and the relief portion is provided at the coupling position of the second restraint bolt. Good. When the end plate is fixed to the outside with a fixing piece provided at the edge, when the battery cell expands, the coupling position of the first restraining bolt that connects the pair of end plates at a position closer to the fixing piece There is a tendency that the deformation amount of the elastic member at the coupling position of the second restraining bolt that connects the pair of end plates at a position away from the fixed piece is larger than the deformation amount of the elastic member at. In this battery module, since the escape portion is formed at the coupling position of the second restraining bolt, it is possible to suitably suppress interference between the middle plate and the inner fastening portion at the coupling position of the second restraining bolt.

FIG. 10 is a schematic cross-sectional view showing a battery module according to the seventh embodiment. As shown in the figure, a battery module 201A according to the seventh embodiment includes an array body 202 in which a plurality of battery cells 203 are arrayed, and a pair of

end plates

206 and 207 that sandwich the array body 202 in the array direction D. And a restraining member 208 that applies a restraining load to the array body 202 in the array direction D. The array body 202 further includes an elastic member 204 and a middle plate 205.

The battery cell 203 constituting the array 202 is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. In the present embodiment, the array body 202 includes eight battery cells 203. Adjacent battery cells 203 are bonded with, for example, a double-sided tape. Each battery cell 203 may be arranged in a state of being held by a resin cell holder. A heat transfer plate may be disposed between adjacent battery cells 203.

Each battery cell 203 contains an electrode assembly and an electrolytic solution in a hollow case having a substantially rectangular parallelepiped shape, for example. A pair of electrode terminals (not shown) are provided apart from each other on the top surface of the case. One of the electrode terminals is a positive electrode terminal connected to the positive electrode of the electrode assembly, and the other of the electrode terminals is a negative electrode terminal connected to the negative electrode of the electrode assembly. The positive electrode terminal and the negative electrode terminal are arranged adjacent to each other. The adjacent positive electrode terminal and negative electrode terminal are connected to each other by a bus bar member. Thereby, the

adjacent battery cells

203 and 203 are electrically connected in series.

The elastic member 204 is used for the purpose of preventing the battery cell 203, the

end plates

206 and 207, and the restraining member 208 from being damaged by restraint load when the battery cell 203 is expanded. The elastic member 204 is formed in a rectangular plate shape by, for example, urethane rubber sponge. The elastic member 204 is disposed at one end of the array body 202 in the array direction D. Examples of other forming materials of the elastic member 204 include ethylene propylene diene rubber (EPDM), chloroprene rubber, and silicon rubber. Further, the elastic member 204 is not limited to rubber but may be a spring material or the like.

The middle plate 205 is, for example, a resin plate member. The middle plate 205 has a substantially rectangular plate shape corresponding to the shape of the battery cell 203 when viewed from the arrangement direction D, and the battery cell 203 located on the most one side (elastic member 204 side) in the arrangement direction D. And the elastic member 204. The middle plate 205 suppresses variation in load applied to each battery cell 203 from the elastic member 204. At the four corners of the middle plate 205, insertion holes 205a through which the restraining bolts 212 described later are inserted are provided.

The

end plates

206 and 207 are, for example, metal plate members. Similarly to the middle plate 205, the

end plates

206 and 207 have a substantially rectangular plate shape corresponding to the shape of the battery cell 203 when viewed from the arrangement direction D. One end plate 206 is disposed so as to contact the elastic member 204. The other end plate 207 is disposed so as to contact the battery cell 203 located on the most other side in the arrangement direction D. At the four corners of the

end plates

206 and 207,

insertion holes

206a and 207a through which the restricting bolts 212 are inserted are provided, respectively.

At the edge 206b of the end plate 206, a fixing piece 209 used for fixing to the outside (here, the casing 210) is provided. The fixed piece 209 protrudes from the edge 206 b of the end plate 206 at a substantially right angle to the end plate 206. The fixing piece 209 is provided with a plurality of insertion holes 209 a through which the fixing bolts 211 are inserted along the edge 206 b of the end plate 206. A similar fixing piece 209 is also provided on the edge 207 b of the end plate 207. The battery module 201 A is fixed to the casing 210 by screwing the fixing bolts 211 passed through the insertion holes 209 a into the bolt holes 210 a provided in the casing 210.

The restraining member 208 includes a restraining bolt 212, an inner fastening portion 213, and an outer fastening portion 214. The restraint bolt 212 is a long bolt having a head portion 212a, and a screw portion 212b is formed at the tip. The restraint bolt 212 is stretched between the pair of

end plates

206 and 207 to connect the

end plates

206 and 207 to each other. The restraining member 208 is, as the restraining bolt 212, a first restraining bolt 212A that connects the pair of

end plates

206 and 207 at a position close to the securing piece 209, and is further away from the securing piece 209 than the first restraining bolt 212A. Two second restraining bolts 212B that connect the pair of

end plates

206, 207 to each other at each position are provided.

The restraint bolt 212 is passed through the

insertion holes

205a, 206a, and 207a so that the middle plate 205 and the

end plates

206 and 207 are inserted from the end plate 207 side. An outer fastening portion 214 formed of a hexagonal nut is screwed to the screw portion 212b of the restraining bolt 212 protruding from the end plate 206. The outer fastening portion 214 fastens the end plate 206 from the outside in the arrangement direction D, and sandwiches the pair of

end plates

206 and 207 between the head 212a of the restraining bolt 212. As a result, the battery cell 203, the elastic member 204, and the middle plate 205 are sandwiched and unitized, and a predetermined restraining load is applied to the battery cell 203, the elastic member 204, and the middle plate 205 via the

end plates

206, 207. Has been. This restraining load is balanced with the elastic repulsive force of the elastic member 204, and is about several hundred N, for example.

Furthermore, an inner fastening portion 213 formed of a nut is screwed to the screw portion 212b of the restraining bolt 212. The inner fastening portion 213 has a hexagonal shape similar to the outer fastening portion 214 when viewed from the arrangement direction D. The thickness of the inner fastening portion 213 (thickness in the arrangement direction D) is thinner than the thickness of the outer fastening portion 214, and is, for example, about half the thickness of the outer fastening portion 214. The inner fastening portion 213 fastens the end plate 206 from the inner side in the arrangement direction D, and sandwiches the end plate 206 with the outer fastening portion 214 at the coupling position P of the restraining bolt 212. The coupling position P of the restraint bolt 212 is a position corresponding to the restraint bolt 212 in the end plate 206, and more specifically, is a peripheral portion of the insertion hole 206a. A large axial force acts on the end plate 206 by being fastened from both sides by the fastening force of the inner fastening portion 213 and the outer fastening portion 214. This axial force is larger than the restraining load, for example, about several thousand N. In addition, the shape of the inner side fastening part 213 and the outer side fastening part 214 when viewed from the arrangement direction D is not limited to a hexagonal shape, and may be other shapes such as a circular shape.

The battery module 201A is assembled in the following process. First, the plurality of battery cells 203, the elastic member 204, the middle plate 205, and the end plate 207 are arranged along the arrangement direction D, and the restraint bolt 212 is inserted into the middle plate 205 and the end plate 207 from the end plate 207 side. Subsequently, the inner fastening portion 213 is screwed into the screw portion 212 b of the restraining bolt 212. At this time, the inner fastening portion 213 is positioned inside the assembly position of the end plate 206 and outside the assembly position of the middle plate 205 so as not to hinder the work in the subsequent process.

Subsequently, the end plate 206 is disposed outside the elastic member 204, and the restraint bolt 212 is inserted through the end plate 206. Subsequently, the outer fastening portion 214 is screwed into the threaded portion 212b of the restraining bolt 212, and a predetermined restraining load is applied to the battery cell 203, the elastic member 204, and the middle plate 205. Subsequently, the inner fastening portion 213 is rotated and moved outward in the arrangement direction D, whereby the end plate 206 is fastened from both sides by the inner fastening portion 213 and the outer fastening portion 214, and a predetermined axial force is applied to the end plate 206. Act. Thus, the battery module 201A is obtained. In order to improve the assembling property, the clearance between the

insertion holes

206a and 207a of the

end plates

206 and 207 and the shaft portion of the restraining bolt 212 is the same as the clearance between the insertion hole 205a of the middle plate 205 and the shaft portion of the restraining bolt 212. The clearance between is larger.

Next, a case where the battery cell 203 expands due to deterioration or overcharge will be described. As shown in FIG. 11, as the battery cell 203 expands in the arrangement direction D, the middle plate 205 moves to the end plate 206 side, and the elastic member 204 is compressed and deformed. Here, as shown in FIG. 12, as the amount of compressive deformation of the elastic member 204 increases, the restraining load applied to the battery cell 203, the elastic member 204, the middle plate 205, and the

end plates

206, 207 increases. Along with this, the reaction force of the restraint load acting on the restraint bolt 212 and the outer fastening portion 214 also increases. For this reason, when the restraining load exceeds a predetermined breaking load, the member having the lowest strength among those members, for example, the

end plates

206 and 207 or the restraining bolt 212 is broken. In order to avoid this breakage, the battery module 201A is designed so that the elastic member 204 does not compressively deform beyond the allowable compression amount corresponding to the breakage load.

In the battery module 201A, when the elastic member 204 is compressed between the middle plate 205 and the end plate 206 until the allowable compression amount for expansion of the battery cell 203 is reached between the middle plate 205 and the end plate 206 at the coupling position P of the restraint bolt 212. An escape portion (escape space) 215 A that forms a gap S is provided between 205 and the inner fastening portion 213. In the present embodiment, the escape portion 215A is configured by making the thickness of the inner fastening portion 213 thinner than the thickness of the elastic member 204 when deformed to reach the allowable compression amount. That is, the thickness of the inner fastening portion 213 is smaller than the thickness obtained by subtracting the allowable compression amount from the thickness of the elastic member 204 before the battery cell 203 is expanded (initial state). Thereby, even when the elastic member 204 is compressed and deformed until the allowable compression amount is reached, the middle plate 205 and the inner fastening portion 213 are not in contact with each other.

As described above, in the battery module 201A of the present embodiment, the end plate 206 is fastened from both sides by the inner fastening portion 213 and the outer fastening portion 214 at the coupling position P of the restraint bolt 212, and the inner fastening portion 213 and the outer fastening portion 214 are tightened. By generating a large axial force (fastening force) between them, the restraint bolt 212 can be firmly fixed to the end plate 206. For this reason, interference with the restraint bolt 212 and the end plate 206 can be suppressed. Further, in the battery module 201A, the elastic member 204 is interposed between the middle plate 205 and the end plate 206 on the elastic member 204 side at the coupling position P of the restraint bolt 212 until the allowable compression amount for the expansion of the battery cell 203 is reached. An escape portion 215A that forms a gap S between the middle plate 205 and the inner fastening portion 213 when compressed and deformed is provided. Thereby, even when the battery cell 203 expand | swells and the elastic member 204 is compressed, it can suppress that the middle plate 205 interferes with the inner side fastening part 213. FIG. Therefore, according to the battery module 201A, the reliability can be improved.

Also, in the battery module 201A, the escape portion 215A is configured by making the thickness of the inner fastening portion 213 thinner than the thickness of the elastic member 204 when it is deformed to reach the allowable compression amount. Thereby, it can suppress that the middle plate 205 interferes with the inner side fastening part 213 with a simple structure.

Further, in the battery module 201A, the escape portion 215A is located at the coupling position P of the second restraint bolt 212B that couples the pair of

end plates

206 and 207 at a position farther from the fixed piece 209 than the first restraint bolt 212A. Is provided. When the

end plates

206 and 207 are fixed to the casing 210 at the fixing pieces 209 provided on the edges 206b and 207b, when the battery cell 203 is expanded, the pair of

end plates

206 and 207 are positioned near the fixing pieces 209. The second restraint bolt 212B that couples the pair of

end plates

206, 207 at a position farther from the fixed piece 209 than the deformation amount of the elastic member 204 at the coupling position P of the first restraint bolt 212A that couples the two. The amount of deformation of the elastic member 204 at the coupling position P tends to increase.

In this regard, in the battery module 201A, since the escape portion 215A is formed at the coupling position P of the second restraining bolt 212B, the middle plate 205 and the inner fastening portion 213 are at the coupling position P of the second restraining bolt 212B. Interference can be suitably suppressed. In the above embodiment, the escape portion 215A is also provided at the coupling position P of the first restraining bolt 212A that connects the pair of

end plates

206 and 207 at a position near the fixed piece 209. 215A may not be provided at the coupling position P of the first restraining bolt 212A, but may be provided only at the coupling position P of the second restraining bolt 212B.

As mentioned above, although one embodiment of the present invention was described, the present invention is not limited to the above embodiment. For example, the battery module may be configured like a battery module 201B of the eighth embodiment shown in FIG. In the eighth embodiment, the escape portion 215B is configured by disposing an inner fastening portion 213 in a recess 206d provided on a surface 206c of the end plate 206 facing the middle plate 205. An end (part) of the inner fastening portion 213 on the end plate 206 side is disposed in the recess 206d. The thickness of the inner fastening portion 213 is approximately the same as the thickness of the outer fastening portion 214. The recess 206d has a larger cross-sectional shape than the inner fastening portion 213 when viewed from the arrangement direction D so that the inner fastening portion 213 can be disposed in the recess 206d. The amount of protrusion of the inner fastening portion 213 from the recess 206d is smaller than the thickness of the elastic member 204 when the inner fastening portion 213 is deformed to reach the allowable compression amount. Thereby, even when the elastic member 204 is compressed and deformed until the allowable compression amount is reached, the middle plate 205 and the inner fastening portion 213 are not in contact with each other.

Even in the eighth embodiment, similarly to the seventh embodiment, even when the battery cell 203 expands and the elastic member 204 is compressed, the middle plate 205 can be prevented from interfering with the inner fastening portion 213. . In addition, the clearance S between the middle plate 205 and the inner fastening portion 213 can be reliably ensured when the elastic member 204 is compressed and deformed until the allowable compression amount is reached. The recess 206d may be provided so as to reach a position facing the elastic member 204 on the facing surface 206c. In this case, when the battery cell 203 is expanded, since the elastic member 204 enters the recess 206d, an increase in the restraining load is suppressed, so that interference between the middle plate 205 and the inner fastening portion 213 can be further suppressed. The inner fastening portion 213 can be thickened. In addition, a recess other than the recess 206d may be provided at a position facing the elastic member 204 on the facing surface 206c. Even in this case, an increase in the restraining load when the battery cell 203 is expanded can be suppressed, and interference between the middle plate 205 and the inner fastening portion 213 can be further suppressed.

The battery module may be configured as a battery module 201C of the ninth embodiment shown in FIG. In the ninth embodiment, the escape portion 215C is configured by providing a concave portion 205c into which the inner fastening portion 213 enters when the elastic member 204 is compressed and deformed on a surface 205b of the middle plate 205 facing the end plate 206. . When the elastic member 204 is compressed and deformed, the end (part) of the inner fastening portion 213 on the middle plate 205 side enters the recess 205c. The thickness of the inner fastening portion 213 is approximately the same as the thickness of the outer fastening portion 214. The concave portion 205c has a larger cross-sectional shape than the inner fastening portion 213 when viewed from the arrangement direction D so that the inner fastening portion 213 can be disposed in the concave portion 205c. The thickness of the inner fastening portion 213 is smaller than the length obtained by adding the depth of the concave portion 205c to the thickness of the elastic member 204 when the inner fastening portion 213 is deformed to an allowable compression amount. Thereby, even when the elastic member 204 is compressed and deformed until the allowable compression amount is reached, the middle plate 205 and the inner fastening portion 213 are not in contact with each other.

Even in the ninth embodiment, similarly to the seventh embodiment, even when the battery cell 203 expands and the elastic member 204 is compressed, the middle plate 205 can be prevented from interfering with the inner fastening portion 213. . In addition, the clearance S between the middle plate 205 and the inner fastening portion 213 can be reliably ensured when the elastic member 204 is compressed and deformed until the allowable compression amount is reached. Note that the recess 205c may be provided so as to reach a position facing the elastic member 204 on the facing surface 205b. In this case, when the battery cell 203 expands, since the elastic member 204 enters the recess 205c, an increase in the restraining load is suppressed, so that the interference between the middle plate 205 and the inner fastening portion 213 can be further suppressed. The inner fastening portion 213 can be thickened.

The battery module may be configured as in the first modification shown in FIG. In the first modification, the inner fastening portion 213 is constituted by a flange portion 212 c provided on the restraining bolt 212. The flange portion 212c has, for example, an annular shape, and is coupled to one end portion side of the restraint bolt 212 by welding or the like. A screw portion 212d is provided on the front end side of the restraint bolt 212 with respect to the flange portion 212c. A screw portion is provided on the proximal end side of the restraint bolt 212, and, for example, a double nut is screwed to the screw portion. In this example, a pair of

end plates

206 and 207 are sandwiched between the outer fastening portion 214 and the double nut. Further, the end plate 206 is sandwiched between the flange portion 212c (inner fastening portion 213) and the outer fastening portion 214. The point that the escape portion 215A is provided at the coupling position P of the restraining bolt 212 is the same as in the seventh embodiment.

In the assembly process of the first modified example, first, after the restraint bolt 212 is inserted into the end plate 206, the outer fastening portion 214 is screwed into the screw portion 212b of the restraint bolt 212, and the end plate 206 is joined to the inner fastening portion 213. Tighten from both sides by the flange portion 212c and the outer fastening portion 214. Subsequently, the plurality of battery cells 203, the elastic member 204, the middle plate 205, and the end plate 206 are arranged along the arrangement direction D, and the restraining bolt 212 is inserted into the middle plate 205 and the end plate 207 from the end plate 206 side. . Subsequently, a double nut is screwed into the screw portion on the proximal end side of the restraint bolt 212, and a predetermined restraint load is applied to the battery cell 203, the elastic member 204, and the middle plate 205. Thus, the battery module of the first modification is obtained. Even in the first modification example, similarly to the seventh embodiment, even when the battery cell 203 expands and the elastic member 204 is compressed, the middle plate 205 can be prevented from interfering with the inner fastening portion 213. .

The battery module may be configured as in the second modified example shown in FIG. In the second modification, the outer fastening portion 214 is constituted by the head portion 212e of the restraining bolt 212. A screw portion 212f into which the inner fastening portion 213 is screwed is provided at a portion adjacent to the head portion 212e in the restraint bolt 212. Similar to the first modified example, a double nut is screwed to a screw portion provided on the base end side (the side opposite to the head portion 212e) of the restraining bolt 212, and the outer fastening portion 214 and the double nut are connected to each other. A pair of

end plates

206 and 207 are sandwiched between them. The end plate 206 is sandwiched between the inner fastening portion 213 and the head portion 212e (outer fastening portion 214). The point that the escape portion 215A is provided at the coupling position P of the restraining bolt 212 is the same as in the seventh embodiment. In the second modification, the restraining bolt 212 is inserted through the middle plate 205 and the end plate 207 from the end plate 206 side.

In the assembly process of the second modified example, first, after the restraint bolt 212 is inserted into the end plate 206, the inner fastening portion 213 is screwed into the screw portion 212f of the restraint bolt 212, and the end plate 206 is joined to the inner fastening portion 213. And it tightens from both sides by the outer side fastening part 214 (head 212e). Other points are the same as in the case of the first modification. Also according to the second modified example, similarly to the seventh embodiment, even when the battery cell 203 expands and the elastic member 204 is compressed, the middle plate 205 can be prevented from interfering with the inner fastening portion 213. .

Any two of the escape portion 215A of the seventh embodiment, the escape portion 215B of the eighth embodiment, and the escape portion 215C of the ninth embodiment described above may be provided, or all three may be provided. .

DESCRIPTION OF SYMBOLS 1A ... Battery module, 2 ... Array, 3 ... Battery cell, 4 ... Elastic member, 6, 7 ... End plate, 8A ... Restraint member, 12 ... Restraint bolt, 12c ... Cylindrical part, 12d ... Screw part, 12e ... Step Part, 12g ... collar part, 12h ... head part, 13 ... inner fastening part, 14 ... outer fastening part, 16 ... step part, D ... arrangement direction, 101 ... battery module, 102 ... array, 103 ... battery cell, 104 DESCRIPTION OF SYMBOLS ... Elastic member, 106,107 ... End plate, 108 ... Restraint member, 112 ... Restraint bolt, 112A ... 1st restraint bolt, 112B ... 2nd restraint bolt, 113 ... Inner side fastening part, 114 ... Outer side fastening part, 113A ... Inner fastening portion at the coupling position of the first restraining bolt, 113B ... Inner fastening portion at the coupling position of the second restraining bolt, 114A ... Outer fastening at the coupling position of the first restraining bolt , 114B: outer fastening portion at the coupling position of the second restraint bolt, 201A, 201B, 201C ... battery module, 202 ... array, 203 ... battery cell, 204 ... elastic member, 205 ... middle plate, 205b ... opposite surface , 205c ... recess, 206, 207 ... end plate, 206b, 207b ... edge, 206c ... facing surface, 206d ... recess, 208 ... restraint member, 209 ... fixing piece, 212 ... restraint bolt, 213 ... inner fastening part, 214 ... outer fastening part, 215A, 215B, 215C ... relief part, S ... gap.

Claims

An array having a plurality of battery cells arranged along the arrangement direction;
A pair of end plates sandwiching the array in the array direction;
A restraint bolt that connects the pair of end plates to each other, and a restraint member that applies a restraint load in the array direction to the array,
The said restraining member is a battery module containing the inner side fastening part which fastens one said end plate from the inner side in the coupling | bonding position of the said restraint bolt, and the outer side fastening part fastened from the outer side.
In the array, further comprising an elastic member arranged unevenly on one side of the array direction,
The battery module according to claim 1, wherein the inner fastening portion and the outer fastening portion fasten the end plate on the one side at a coupling position of the restraint bolt.
The battery module according to claim 2, wherein the inner fastening portion is constituted by a nut screwed into a screw portion of the restraining bolt.
The constraining bolt is a stepped bolt in which a screw portion having a smaller diameter than the cylindrical portion is provided on the tip side of the cylindrical portion,
The battery module according to claim 2, wherein the inner fastening portion is configured by a step portion between the cylindrical portion and the screw portion.
The battery module according to claim 2, wherein the inner fastening portion is configured by a flange provided on the restraining bolt.
The battery module according to claim 2 or 3, wherein the outer fastening portion is constituted by a head of the restraining bolt.
The battery module according to any one of claims 2 to 5, wherein the outer fastening portion is configured by a nut screwed into a screw portion of the restraining bolt.
The inner surface of the one end plate is provided with a step portion for engaging the inner fastening portion and the restraining bolt in the rotational direction to prevent the restraining bolt from rotating. The battery module according to any one of 1 to 7.
The outer surface of the said one end plate is provided with the step part for engaging the said outer fastening part and the rotation direction of the said restraint bolt, and stopping the said restraint bolt. The battery module according to any one of 1 to 7.
The battery module according to claim 1, wherein the strength of the outer fastening portion with respect to the load in the arrangement direction is higher than the strength of the inner fastening portion with respect to the load in the arrangement direction.
The battery module according to claim 10, wherein an area of a contact surface between the outer fastening portion and the one end plate is larger than an area of a contact surface between the inner fastening portion and the one end plate.
The battery module according to claim 10 or 11, wherein a hardness of the outer fastening portion is higher than a hardness of the inner fastening portion.
Fixing pieces used for fixing to the outside are provided at the edges of the pair of end plates,
The restraining member includes a first restraining bolt that couples the pair of end plates at a position closer to the fixing piece, and a second restraining bolt that couples the pair of end plates at a position away from the fixing piece. And having
The strength with respect to the load in the arrangement direction of the outer fastening portion at the coupling position of the second restraint bolt is higher than the strength with respect to the load in the arrangement direction of the outer fastening portion at the coupling position of the first restraint bolt. The battery module according to any one of claims 10 to 12.
An elastic member arranged at one end in the arrangement direction in the array;
In the array, further comprising a middle plate disposed between the elastic member and the battery cell located closest to the elastic member,
The inner fastening portion and the outer fastening portion fasten the end plate on the elastic member side at the binding position of the restraint bolt,
When the elastic member is compressed and deformed until the allowable compression amount for the expansion of the battery cell is reached between the middle plate and the end plate on the elastic member side at the binding position of the restraint bolt. The battery module according to claim 1, wherein an escape portion that forms a gap is provided between the inner fastening portion and the inner fastening portion.
The battery module according to claim 14, wherein the escape portion is configured by making a thickness of the inner fastening portion thinner than a thickness of the elastic member when compressed and deformed to reach the allowable compression amount. .
The battery module according to claim 14, wherein the escape portion is configured by disposing the inner fastening portion in a recess provided on a surface of the end plate on the elastic member side facing the middle plate. .
The escape portion is configured by providing a concave portion into which the inner fastening portion enters when the elastic member is compressed and deformed on a surface of the middle plate facing the end plate on the elastic member side. 14. The battery module according to 14.
Fixing pieces used for fixing to the outside are provided at the edges of the pair of end plates,
The restraint member includes a first restraint bolt that connects the pair of end plates at a position closer to the fixed piece, and the pair of end plates at a position farther from the fixed piece than the first restraint bolt. A second restraining bolt for connecting
The battery module according to any one of claims 14 to 17, wherein the escape portion is provided at a coupling position of the second restraining bolt.