JP6705285B2 - Battery pack and battery module - Google Patents

Description

The present invention relates to a battery pack and a battery module.

A battery pack is known in which a battery module in which battery cells are arranged is attached to a housing or the like. Patent Document 1 discloses a case in which a battery module having an array body in which battery cells are arrayed, a pair of end plates arranged at both ends in the array direction of the array body, and a restraining band for fastening the end plates to each other are casings. The battery pack housed in is described. In this battery pack, when the battery cell presses the end plate due to the expansion of the battery cell, the restraint band is intentionally deformed to bend the end plate, thereby suppressing the deformation due to the expansion of the battery cell.

JP, 2010-040295, A

In a battery pack in which a pair of fixing members such as end plates are fixed to the wall surface of the housing, and the pair of fixing members are fastened by fastening members such as bolts, for example, the battery cells are It expands, and the array end of the array body presses the fixing member. As a result, the pair of fixing members are deformed with the wall surface side of the housing as a fulcrum, and the array member is deformed so that the central portion of the array member is separated from the wall surface of the housing, so that stress concentration occurs in the fastening member. In particular, if stress concentration occurs in the fastening member at the final stage of deterioration in which the battery cell has a large expansion amount and a relatively large load is applied to the fastening member, there is a high possibility that the fastening member will be damaged.

An object of the present invention is to provide a battery pack and a battery module that can reduce stress concentration on the fastening member at the end of deterioration.

The battery pack of the present invention is a battery pack in which a battery module is housed in a housing, and the battery module includes an array body including a plurality of battery cells arranged in one direction, and an array end of the array body. And a fastening member for applying a restraining load to the array in the array direction of the battery cells, and each of the plurality of battery cells is The battery cell having the first side surface facing the wall surface is arranged so as to be convex toward the wall surface, and the battery cell arranged closer to the array end with respect to the central portion of the array body has the first side surface. It is arranged so that the angle formed between the side surface and the wall surface is large.

In the battery pack having this configuration, the plurality of battery cells are arranged so as to be convex toward the wall surface, and the battery cell arranged closer to the array end with respect to the central portion of the array has the first side surface and the wall surface. It is arranged so that the angle it makes is large. Therefore, the array body is preliminarily curved so that its central portion approaches the wall surface of the housing. Therefore, even if the array body is deformed such that the central portion of the array body is separated from the wall surface of the housing due to the expansion of the battery cells with the passage of time, the array body is in a pre-curved state and is not curved (the array direction is Since it is in a state close to a straight line), warp deformation of the array body which is convex on the side opposite to the wall surface of the housing is reduced. As a result, the deformation of the fastening member due to the deformation of the array body is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member at the final stage of deterioration.

A battery pack in which a battery module is housed in a housing, wherein the battery module is arranged at an array end including a plurality of battery cells arranged in one direction, and at an array end of the housing. A pair of fixing members fixed to the wall surface of the battery, and a fastening member that applies a restraining load to the array in the array direction of the battery cells, and each of the plurality of battery cells crosses the array direction. The plurality of battery cells are arranged so as to be convex toward the wall surface, and the distance between the second side surfaces facing each other in the plurality of adjacent battery cells becomes smaller as the distance from the wall surface increases. It is arranged.

In the battery pack having this configuration, the plurality of battery cells are arranged so as to be convex toward the wall surface, and the plurality of adjacent battery cells are arranged such that the distance between the second side surfaces facing each other becomes smaller as the distance from the wall surface increases. Has been done. Therefore, the array body is preliminarily curved so that its central portion approaches the wall surface of the housing. Therefore, even if the array body is deformed so that the central portion of the array body is separated from the wall surface of the housing due to the expansion of the battery cells with the passage of time, the array material that is convex on the side opposite to the wall surface of the housing Warp deformation is reduced. As a result, the deformation of the fastening member due to the deformation of the array body is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member at the final stage of deterioration.

In the battery pack of the present invention, each of the pair of fixing members has a constraining surface that constrains the array body and a fixing surface that is fixed to the housing, and constrains the angle between the constraining surface and the fixing surface. The angle opposite the array with respect to the face may be obtuse. In this case, when the battery cell expands with the passage of time, the restraining surface is inclined in advance in a direction opposite to the direction in which the deformation of the fixing member progresses. Therefore, it becomes easy to arrange the array body so as to be convex toward the wall surface of the housing.

The battery pack of the present invention may further include an elastic heat conducting member arranged between the array and the wall surface. In this case, for example, by compressing the heat conducting member in a state where the array body is curved in advance, the array body is deformed so that the central portion of the array body is separated from the wall surface of the housing due to the expansion of the battery cells over time. Even if it does, the heat conducting member can be restored. Therefore, it becomes difficult to form a gap between the array body and the wall surface in which the heat conducting member is not interposed, and it is possible to prevent the cooling performance of the battery cells from deteriorating over time.

In the battery pack of the present invention, the heat conducting member may have adhesiveness. In this case, for example, even if the array body is deformed such that the central portion of the array body is separated from the wall surface of the housing due to the expansion of the battery cells with the passage of time, the heat conductive member has the adhesiveness and the array body and the wall surface. It becomes easy to maintain the state of being in contact with both. Therefore, it becomes difficult to form a gap between the array body and the wall surface in which the heat conducting member is not interposed, and it is possible to prevent the cooling performance of the battery cells from deteriorating over time.

As a configuration that suitably exhibits the above-described effects, the heat conducting member may be made of a rubber-based material.

In the battery pack of the present invention, the fastening members are arranged at a position farther from the wall surface than the position of the first fastening member and a first fastening member that applies a restraining load to the wall surface side of the array body in the arrangement direction of the battery cells. A second fastening member that applies a restraining load to the body in the arrangement direction of the battery cells, and the restraining load of the first fastening member may be smaller than the restraining load of the second fastening member. In this case, since the restraint load on the wall surface side becomes small, it becomes easy to bend the array body in advance so that the central portion of the array body approaches the wall surface.

In addition, the battery module of the present invention includes an array including a plurality of battery cells arranged along one direction, a pair of fixing members arranged at an array end of the array and fixed to an external component, and an array. A fastening member that applies a restraining load to the body in the arrangement direction of the battery cells, each of the pair of fixing members has a contact surface that contacts an external component, and each of the plurality of battery cells includes a pair of Has a first side surface facing the reference surface including the contact surface of the fixing member, and the plurality of battery cells are arranged so as to be convex toward the reference surface, and are arranged near the array end with respect to the central portion of the array. The arranged battery cells are arranged such that the angle formed by the first side surface and the reference surface is larger.

In the battery module having this configuration, the plurality of battery cells are arranged so as to be convex toward the reference surface, and the battery cells arranged closer to the arrangement end with respect to the central portion of the arrangement body have the first side surface and the reference surface. They are arranged so that the angle formed by and becomes large. Therefore, the array body is in a pre-curved state such that the central portion thereof approaches the reference plane. Therefore, even if the array body is deformed so that the central portion of the array body is separated from the reference plane due to the expansion of the battery cells with the passage of time, the warp deformation of the array body that is convex on the side opposite to the reference plane is reduced. To be done. As a result, the deformation of the fastening member due to the deformation of the array body is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member at the final stage of deterioration.

The battery module of the present invention includes an array body including a plurality of battery cells arranged in one direction, a pair of fixing members arranged at the array ends of the array body and fixed to an external component, and an array body. And a fastening member for applying a restraining load in the arrangement direction of the battery cells, wherein each of the pair of fixing members has a contact surface that contacts an external component, and each of the plurality of battery cells is arranged in the arrangement direction. The plurality of battery cells having the intersecting second side surfaces are arranged so as to be convex toward the reference surface including the contact surfaces of the pair of fixing members, and the second side surfaces facing each other in the plurality of adjacent battery cells. Are arranged so that the distance becomes smaller as the distance from the reference plane increases.

In the battery module having this configuration, the plurality of battery cells are arranged so as to be convex toward the reference surface, and the distance between the second side surfaces facing each other in the plurality of adjacent battery cells decreases as the distance from the reference surface increases. Are arranged in. Therefore, the array body is in a pre-curved state such that the central portion thereof approaches the reference plane. Therefore, even if the array body is deformed so that the central portion of the array body is separated from the reference plane due to the expansion of the battery cells with the passage of time, the warp deformation of the array body that is convex on the side opposite to the reference plane is reduced. To be done. As a result, the deformation of the fastening member due to the deformation of the array body is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member at the final stage of deterioration.

According to the present invention, it is possible to provide a battery pack and a battery module that can reduce stress concentration on the fastening member at the final stage of deterioration.

FIG. 1 is a schematic side view of the battery pack according to the present embodiment. FIG. 2 is a partially exploded perspective view of the battery module of FIG. FIG. 3 is a partially exploded perspective view of the battery module of FIG. FIG. 4 is a schematic side view for explaining an example of a method for manufacturing a battery pack. FIG. 5 is a schematic side view showing a state in which the battery module of FIG. 4 is fixed to a housing. FIG. 6 is a schematic side view showing a deformed state of the array body of FIG. FIG. 7 is a schematic side view of a battery pack according to a modification. FIG. 8 is a schematic side view showing a deformed state of the array of FIG. 7.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements or corresponding elements may be denoted by the same reference symbols, and redundant description may be omitted. In the following description, the orthogonal coordinate system S attached to the drawings may be used.

As shown in FIG. 1, the battery pack 100 according to the present embodiment includes a housing (external component) 1, a battery module 2, and a heat conduction member (TIM: Thermal Interface Material) T. The housing 1 has a wall surface 1s. The battery module 2 is housed in the housing 1 of the battery pack 100. The battery module 2 is fixed to the wall surface 1s of the housing 1. The heat conducting member T is arranged between the battery module 2 and the wall surface 1s. The heat conducting member T is a member having elasticity, and is a plate-like member made of, for example, a rubber material.

The battery module 2 includes an array body 2a including a plurality of battery cells 11, a pair of fixing members 3 respectively arranged at array ends of the array body 2a, and a constraint in the array direction A of the battery cells 11 with respect to the array body 2a. And a fastening member 4 for applying a load. In the array 2a, a plurality of battery cells 11 are arrayed along one direction. The number of battery cells 11 is seven as an example. The one direction is not particularly limited, but in the example of FIG. 1, it is the X direction shown by the orthogonal coordinate system S. In the present embodiment, before the deterioration of the battery cells 11 progresses, the plurality of battery cells 11 are arranged so as to be convex toward the wall surface 1s. Therefore, the arrangement direction A of the battery cells 11 extends along a curve that is along one direction (here, the X direction) and is convex toward the wall surface 1s. The arrangement direction A may change with the progress of deterioration of the battery cells 11 (details will be described later).

As shown in FIG. 2, the battery cell 11 is electrically connected to the electrode assembly 12, the case 13 that houses the electrode assembly 12, and the electrodes (the positive electrode and the negative electrode, respectively) of the electrode assembly 12. And a pair of terminals 14. The electrode assembly 12 includes a plurality of positive electrodes (not shown) and a negative electrode (not shown), and a separator (not shown) arranged between the positive electrode and the negative electrode. The positive electrodes and the negative electrodes are arranged alternately along the arrangement direction A with the separators in between.

The case 13 has a rectangular parallelepiped shape. The case 13 includes a pair of side surfaces 13a and 13b facing each other, a pair of side surfaces 13c and 13d facing each other, and a top surface 13e and a bottom surface 13f facing each other. The side surfaces 13a and 13b are surfaces along the arrangement direction A. The side surfaces 13c and 13d are surfaces that intersect in the arrangement direction A. The side surfaces 13a and 13b connect the side surface 13c and the side surface 13d to each other. The terminal 14 projects from the upper surface 13e. The side surface 13c is a first side surface that faces the wall surface 1s of the housing 1. The pair of side surfaces 13a and 13b are second side surfaces that intersect in the arrangement direction A.

The battery cell 11 is held by the cell holder 20. The cell holder 20 includes a side wall portion 20c and a side wall portion 20d facing each other, a back surface portion 20e and a bottom wall portion 20f. The side wall portions 20c and 20d have a rectangular plate shape. The back surface portion 20e has a rectangular plate shape, and connects the side wall portion 20c and the side wall portion 20d to each other at one longitudinal end of the side wall portions 20c and 20d. The bottom wall portion 20f has a rectangular plate shape, and connects the side wall portion 20c and the side wall portion 20d to each other at the other longitudinal ends of the side wall portions 20c and 20d.

In the cell holder 20, the side wall portions 20c and 20d, the back surface portion 20e, and the bottom wall portion 20f define a rectangular parallelepiped space portion into which the battery cell 11 is fitted. The side wall portions 20c and 20d are arranged on the side surfaces 13c and 13d of the case 13 when the battery cell 11 is fitted in the space portion. Similarly, the rear surface portion 20e is arranged on the upper surface 13e of the case 13. Further, the bottom wall portion 20f is arranged on the bottom surface 13f of the case 13.

The back surface portion 20e is provided with a pair of protruding portions 21. The protruding portion 21 has a rectangular parallelepiped shape. The protruding portion 21 extends along the arrangement direction A. The protruding portion 21 is arranged on the upper surface 13e of the case 13 at a position between the pair of terminals 14 when the battery cell 11 is fitted in the space. A through hole 21h is formed in the protruding portion 21 along the extending direction thereof. Bolts 40 and 41 of the fastening member 4 described later are inserted into the through holes 21h.

Further, a pair of projecting portions 22 is provided at the connecting portion of the bottom wall portion 20f with the side wall portions 20c and 20d. The protruding portion 22 has a rectangular parallelepiped shape. The protruding portion 22 extends along the arrangement direction A. When the battery cell 11 is fitted into the space, the protruding portion 22 is arranged at the end of the bottom surface 13f of the case 13 on the side surface 13c, 13d side. A through hole 22h is formed in the protruding portion 22 along the extending direction thereof. Bolts 42 and 43 of the fastening member 4 described later are inserted into the through holes 22h.

The heat transfer plate 15 includes a rectangular plate-shaped main body portion 15a and a rectangular plate-shaped extending portion 15c. The heat transfer plate 15 is formed in an L-shaped plate shape by the main body portion 15a and the extending portion 15c. The main body portion 15a is arranged on the side surface 13a of the battery cell 11 (case 13). The extending portion 15c extends from the main body portion 15a along the arrangement direction A and is arranged on the side surface 13c of the battery cell 11 (case 13). The extending portion 15c is arranged on the side surface 13c via the side wall portion 20c of the cell holder 20.

The heat transfer plate 15 contacts the battery cell 11 in the main body portion 15a, and also contacts the heat conducting member T on the surface of the extending portion 15c opposite to the side wall portion 20c. That is, the heat transfer plate 15 thermally connects the battery cell 11 and the housing 1 via the heat conductive member T. In the present embodiment, the heat transfer plate 15 is attached to the battery cell 11 so that the fixing surface 31s of the fixing member 3 and the extending portion 15c in the battery module 2 are located on the same side with respect to the battery cell 11. That is, the heat of the battery cells 11 is radiated to the wall surface 1s of the housing 1 via the extending portion 15c.

As shown in FIG. 3, the fixing member 3 has a rectangular plate-shaped restraining portion 30 and a rectangular plate-shaped fixing portion 31. The restraint portion 30 and the fixed portion 31 are, for example, flat plates. The restraint portion 30 extends so as to intersect in the arrangement direction A. The fixed portion 31 is provided at one end of the restraint portion 30 so as to extend along the arrangement direction A. Thereby, the fixing member 3 is formed, for example, in an L-shaped plate shape as a whole.

As shown in FIG. 1, the restraint portion 30 is fastened to each other by the fastening member 4 and the nut 5 in a state where the plurality of battery cells 11 are sandwiched along the arrangement direction A. Thereby, the restraint unit 30 applies a restraining load to the battery cells 11 and restrains the battery cells 11 with each other. That is, the restraint portion 30 includes the restraint surface 30s that restrains the array 2a.

The fixing member 3 is fixed to the wall surface 1s of the housing 1. Specifically, the fixing portion 31 is fixed to the wall surface 1s by the bolt 6 in a state where the fixing surface 31s is in contact with the wall surface 1s. As a result, the array 2a is fixed to the wall surface 1s of the housing 1. The fixing portion 31 includes a fixing surface 31s fixed to the housing 1. The fixed surface 31s is a contact surface that contacts the housing 1. In a state where the array 2a can be fixed to the wall surface 1s of the housing 1, the pair of fixing surfaces 31s is included in a single plane (reference surface).

The constraining surface 30s and the fixed surface 31s intersect at an angle θ. The angle θ is an angle between the constraining surface 30s and the fixed surface 31s on the side opposite to the array 2a with respect to the constraining surface 30s. The angle θ is preferably an obtuse angle larger than 90° so that the angle θ approaches 90° at the end of deterioration of the battery cell 11 in which the expansion amount of the battery cell 11 is large.

Returning to FIG. 3, the restraint portion 30 includes a pair of projecting portions 32 provided on one outer edge 30e of the restraint portion 30 and a pair of projecting portions provided on the outer edge 30f of the restraint portion 30 opposite to the outer edge 30e. And a part 33. The restraint portion 30 faces the side surfaces 13a and 13b of the battery cell 11 (case 13).

The protruding portion 32 has a rectangular plate shape. The projecting portion 32 projects from the side surfaces 13 a and 13 b of the battery cell 11 on the upper surface 13 e side of the battery cell 11 when viewed in the arrangement direction A. The projecting portion 32 is provided with a through hole 32h. The through hole 32h overlaps with the through hole 21h of the projecting portion 21 of the cell holder 20 when viewed from the arrangement direction A. Bolts 40 and 41 of the fastening member 4 described later are inserted into the through holes 32h.

The protruding portion 33 has a rectangular plate shape. The projecting portion 33 projects from the side surfaces 13a and 13b of the battery cell 11 on the bottom surface 13f side of the battery cell 11 when viewed in the arrangement direction A. The protruding portion 33 is provided with a through hole 33h. The through hole 33h overlaps with the through hole 22h of the protruding portion 22 of the cell holder 20 when viewed from the arrangement direction A. Bolts 42 and 43 of the fastening member 4, which will be described later, are inserted into the through holes 33h.

The middle plate 7 is arranged between the fixing member 3 on the one end 2b side of the array 2a and the battery cell 11 adjacent to the fixing member 3. A part of the middle plate 7 has substantially the same shape as the fixing member 3 when viewed from the arrangement direction A. Therefore, the middle plate 7 is also provided with a through hole that overlaps with the through holes 32h and 33h in the fixing member 3 when viewed from the arrangement direction A. An elastic member 8 that is compressed according to the expansion of the battery cell 11 is interposed between the middle plate 7 and the fixing member 3.

An insulating film 9 is interposed between the side surfaces 13b of the battery cells 11 and the main body portion 15a of the heat transfer plate 15 between the adjacent battery cells 11. The insulating film 9 has, for example, a rectangular shape having the same size as the main body portion 15a of the heat transfer plate 15. The insulating film 9 has an insulating property and is made of, for example, a material having elasticity.

The fastening member 4 applies a restraining load to the plurality of battery cells 11 (the array 2a) along the array direction A by fastening the pair of fixing members 3 to each other. The battery module 2 includes a plurality (four here) of fastening members 4. The fastening member 4 includes, for example, long bolts 40 to 43 and a nut 5 screwed into each of the bolts 40 to 43. As an example, the bolts 40 to 43 have a hexagonal columnar head portion 4b integrally formed at one end 4a thereof and a screw thread formed at the other end 4c thereof. The nut 5 is screwed onto the other end 4c of the bolts 40 to 43.

The fastening member 4 includes bolts 41 and 43 (first fastening members) that apply a restraining load in the arrangement direction A of the battery cells 11 to the wall surface 1s side of the array 2a, and the wall surface 1s rather than the positions of the bolts 41 and 43. And bolts 40 and 42 (second fastening members) that apply a restraining load to the array 2a in the array direction A of the battery cells 11 at a position distant from. The wall surface 1s side of the array 2a is, for example, the wall surface 1s side with respect to the surface parallel to the wall surface 1s including the axis along the array direction A of the array 2a. The position farther from the wall surface 1s than the positions of the bolts 41 and 43 is, for example, a position on the opposite side of the positions of the bolts 41 and 43 with respect to the axis line along the arrangement direction A of the array 2a. The bolts 40 and 41 are inserted into the through hole 21h of the cell holder 20 holding the battery cells 11, the through hole 32h of the fixing member 3 arranged at the array end of the array 2a, and the through hole of the middle plate 7. .. The bolts 42 and 43 are inserted into the through hole 22h of the cell holder 20 holding the battery cells 11, the through hole 33h of the fixing member 3 arranged at the array end of the array 2a, and the through hole of the middle plate 7. .. 1 and 4 to 8, the bolts 42 and 43, the through holes 22h through which the bolts 42 and 43 are inserted, the through holes 33h, and the nuts 5 screwed into the bolts 42 and 43 are illustrated. Omitted.

In the battery module 2, a plurality of battery cells 11 are arranged so as to be convex toward the wall surface 1s, which will be described in detail with reference to FIG.

Specifically, the plurality of battery cells 11 are arranged such that the angle formed by the side surface 13c and the wall surface 1s becomes larger as the battery cells 11 arranged closer to the array end with respect to the central portion M of the array body 2a. There is. In the following description, for the sake of convenience, the seven battery cells 11 of the array body 2a are sequentially arranged from the other end 2c of the array body 2a to the one end 2b in order of the battery cell 111, the battery cell 112,... 117.

In the example of FIG. 1, the side surface 134c of the battery cell 114 located in the central portion M of the array 2a is substantially parallel to the wall surface 1s. Therefore, the angle B4 (not shown) formed by the side surface 134c of the battery cell 114 and the wall surface 1s is approximately 0°.

The side surface 135c of the battery cell 115 adjacent to the battery cell 114 is inclined with respect to the wall surface 1s at an angle larger than the angle B4 formed by the side surface 134c and the wall surface 1s. That is, the angle B5 formed by the side surface 135c of the battery cell 115 and the wall surface 1s is larger than the angle B4. The side surface 136c of the battery cell 116 adjacent to the battery cell 115 is further inclined with respect to the wall surface 1s than the angle B5 formed by the side surface 135c and the wall surface 1s. That is, the angle B6 formed by the side surface 136c of the battery cell 116 and the wall surface 1s is larger than the angle B5. The side surface 137c of the battery cell 117 adjacent to the battery cell 116 is further inclined with respect to the wall surface 1s than the angle B6 formed by the side surface 136c and the wall surface 1s. That is, the angle B7 formed by the side surface 137c of the battery cell 117 and the wall surface 1s is larger than the angle B6. Therefore, in the battery cells 114 to 117, the battery cell 11 arranged closer to the one end 2b with respect to the central portion M of the array 2a is arranged such that the angle B formed by the side surface 13c and the wall surface 1s becomes larger. There is.

Similarly, the side surface 133c of the battery cell 113 adjacent to the battery cell 114 is inclined with respect to the wall surface 1s at an angle larger than the angle B4 formed by the side surface 134c and the wall surface 1s. That is, the angle B3 formed by the side surface 133c of the battery cell 113 and the wall surface 1s is larger than the angle B4. The side surface 132c of the battery cell 112 adjacent to the battery cell 113 is further inclined with respect to the wall surface 1s than the angle B3 formed by the side surface 133c and the wall surface 1s. That is, the angle B2 formed by the side surface 132c of the battery cell 112 and the wall surface 1s is larger than the angle B3. The side surface 131c of the battery cell 111 adjacent to the battery cell 112 is further inclined with respect to the wall surface 1s than the angle B2 formed by the side surface 132c and the wall surface 1s. That is, the angle B1 formed by the side surface 131c of the battery cell 111 and the wall surface 1s is larger than the angle B2. Therefore, in the battery cells 111 to 114, the battery cells 11 arranged closer to the other end 2c with respect to the central portion M of the array 2a are arranged such that the angle B formed by the side surface 13c and the wall surface 1s is larger. ing. In the example of FIG. 1, the angles B1 and B7, the angles B2 and B6, and the angles B3 and B5 are substantially equal, but the angles B1 to B7 are not limited to this example. Absent.

Further, in the battery module 2, the plurality of battery cells 11 are arranged such that the distance between the side surfaces 13a and 13b facing each other in the plurality of adjacent battery cells 11 becomes smaller as the distance from the wall surface 1s increases.

In the example of FIG. 1, in the adjacent battery cells 111 and 112, the side surface 131a of the battery cell 111 and the side surface 132b of the battery cell 112 face each other. The distance between the side surface 131a and the side surface 132b is the distance L1 at the position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

In the adjacent battery cells 112 and 113, the side surface 132a of the battery cell 112 and the side surface 133b of the battery cell 113 face each other. The distance between the side surface 132a and the side surface 133b is the distance L2 at the position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

In the adjacent battery cells 113 and 114, the side surface 133a of the battery cell 113 and the side surface 134b of the battery cell 114 face each other. The distance between the side surface 133a and the side surface 134b is the distance L3 at the position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

In the adjacent battery cells 114 and 115, the side surface 134a of the battery cell 114 and the side surface 135b of the battery cell 115 face each other. The distance between the side surface 134a and the side surface 135b is the distance L4 at the position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

In the adjacent battery cells 115 and 116, the side surface 135a of the battery cell 115 and the side surface 136b of the battery cell 116 face each other. The distance between the side surface 135a and the side surface 136b is the distance L5 at the position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

In the adjacent battery cells 116 and 117, the side surface 136a of the battery cell 116 and the side surface 137b of the battery cell 117 face each other. The distance between the side surface 136a and the side surface 137b is a distance L6 at a position closest to the wall surface 1s, and becomes smaller as the distance from the wall surface 1s increases.

Therefore, the battery cells 111 to 117 are arranged such that the distance between the side surfaces 13a and 13b facing each other in the plurality of adjacent battery cells 11 becomes smaller as the distance from the wall surface 1s increases. In the present embodiment, the distances L1 to L6 are substantially equal to each other, but the distances L1 to L6 are not limited to this example.

Such a battery module 2 can be obtained, for example, by fixing the battery module 2X shown in FIG. 4 to the wall surface 1s of the housing 1 as shown in FIG. In the example of FIG. 4, in the state where the array 2a is arranged in the array direction A1 that coincides with the X direction, the through holes 21h and 22h of the cell holder 20, the through holes 32h and 33h of the fixing member 3, and the middle plate 7 are formed. Bolts 40 to 43 are inserted into the through holes. In this state, the nut 5 is screwed into the other ends 4c of the bolts 40 to 43 so as to tighten the pair of fixing members 3 with each other with the first restraining load, whereby the restraining load is applied to the array 2a through the fixing member 3. Is added. At this time, the entire insulating film 9 is compressed. The insulating film 9 is compressed substantially uniformly, for example, in the Y direction regardless of the position from the wall surface 1s. Thereby, the battery module 2X is configured. In the battery module 2X, the restraining surface 30s of the fixing member 3 extends in a direction substantially orthogonal to the X direction, and the fixing surface 31s of the fixing member 3 is inclined in the X direction.

Then, as shown in FIG. 5, by loosening the nut 5 at the other ends 4c of the bolts 41 and 43, the restraint load applied to the wall surface 1s side of the array 2a is made smaller than the first restraint load. Reduce to a small second restraint load. At this time, the restraint load on the wall surface 1s side of the insulating film 9 is reduced. The insulating film 9 is in a more compressed state as it is farther from the wall surface 1s in the Y direction, for example. Thereby, the array direction of the array body 2a becomes the array direction A2 in which the array body 2a is curved so as to be convex toward the wall surface 1s. The arrangement direction A2 is the same as the arrangement direction A in the example of FIG. 1, for example. As a result, the angle B formed by the side surface 13c and the wall surface 1s increases as the battery cells 11 are arranged closer to the array end (one end 2b and the other end 2c) with respect to the central portion M of the array 2a. In addition, the distance between the side surfaces 13a and 13b facing each other in the plurality of adjacent battery cells 11 becomes smaller as the distance from the wall surface 1s (reference surface) increases. In this way, the battery module 2 is constructed.

In the battery module 2, the fixing surface 31s of the fixing member 3 extends in the direction along the X direction and is included in the reference surface 3s that is a single plane. As a result, the array 2a is ready to be fixed to the wall surface 1s of the housing 1. In this state, with the fixing surface 31s of the fixing member 3 along the wall surface 1s of the housing 1, the heat conducting member T is interposed between the extending portion 15c of the heat transfer plate 15 and the wall surface 1s, The fixing member 3 is fixed to the wall surface 1s of the housing 1 with the bolt 6. At this time, the heat conducting member T around the central portion M of the array 2a is compressed. Thereby, the battery pack 100 can be obtained.

According to the battery module 2 having the above-described configuration, since the plurality of battery cells 11 are arranged so as to be convex toward the wall surface 1s, the fastening member 4 is at the end of deterioration in which the expansion amount of the battery cells 11 is large. It is possible to reduce the occurrence of stress concentration.

For example, when the battery cells 11 expand as the deterioration of the battery cells 11 progresses and the array ends of the array 2a press the fixing member 3, the pair of fixing members 3 use the wall surface 1s side of the housing 1 as a fulcrum. The array 2a is deformed, and the array 2a is deformed so that the central portion M of the array 2a is separated from the wall surface 1s of the housing 1. Therefore, stress concentration occurs in the fastening member 4. In particular, if stress concentration occurs in the fastening member 4 at the end of deterioration in which the battery cell 11 has a large expansion amount and a relatively large load is applied to the fastening member 4, there is a high possibility that the fastening member 4 will be damaged. ..

In this respect, according to the battery pack 100 and the battery module 2 of the present embodiment, the plurality of battery cells 11 are arranged so as to be convex toward the wall surface 1s (reference surface), and the central portion M of the array body 2a is arranged. On the other hand, the battery cells 11 arranged closer to the array ends (one end 2b and the other end 2c) are arranged such that the angle B formed by the side surface 13c and the wall surface 1s is larger. Further, in the plurality of adjacent battery cells 11, the side surfaces 13a and 13b facing each other are arranged such that the distance between the side surfaces 13a and 13b becomes smaller as the distance from the wall surface 1s (reference surface) increases. Therefore, before the battery cells 11 are inflated, the central portion M of the array 2a is preliminarily curved so as to approach the wall surface 1s of the housing 1. On the other hand, for example, when the battery cell expands as the deterioration of the battery cell progresses, the central portion M of the array 2a is deformed so as to be separated from the wall surface 1s of the housing 1. That is, the direction in which the array body 2a that is curved in advance is convex (the negative direction in the Y direction) and the central portion M of the array body 2a moves due to the expansion of the battery cells 11 over time. The direction (the positive direction in the Y direction) is the opposite direction. Therefore, at least in the initial stage of deterioration of the battery cells 11, the array body 2a approaches from a pre-bent state to a non-bent state (a state in which the array direction A is close to a straight line).

Then, in the final stage of deterioration of the battery cells 11 in which the expansion amount of the battery cells 11 is large, the array direction A3 of the array body 2a approaches the direction along the X direction again as shown in FIG. 6, for example. In this state, since the array 2a is not substantially deformed in the array direction along the X direction, stress concentration is unlikely to occur in the fastening member 4. Therefore, even if the array body 2a is deformed so that the central portion M of the array body 2a is separated from the wall surface 1s of the housing 1 due to the expansion of the battery cells 11 with the passage of time, By comparison, the deformation of the fastening member 4 due to the deformation of the array 2a is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member 4 in the final stage of deterioration.

Even if the expansion amount of the battery cells 11 becomes larger than that in the example of FIG. 6 and the array 2a is warped and deformed so as to be convex on the side opposite to the wall surface 1s of the housing 1, at least the battery is Since the array 2a is pre-curved at the initial stage of deterioration of the cells 11, the warp deformation of the final array 2a at the end of deterioration is reduced as compared with the case where the array 2a is not pre-curved. Becomes Therefore, even when the expansion amount of the battery cell 11 is larger than that in the example of FIG. 6, it is possible to reduce the occurrence of stress concentration in the fastening member 4 at the final stage of deterioration.

Further, in the battery pack 100, each of the pair of fixing members 3 has a constraining surface 30s that constrains the array 2a and a fixing surface 31s that is fixed to the housing 1. Of the angles formed by the constraining surface 30s and the fixed surface 31s, the angle θ on the side opposite to the array 2a with respect to the constraining surface 30s is an obtuse angle. As a result, when the battery cells 11 expand over time, the restraint surface 30s is preliminarily inclined in a direction opposite to the direction in which the deformation of the fixing member 3 progresses. Therefore, it becomes easy to arrange the array bodies 2a so as to be convex toward the wall surface 1s of the housing 1.

In addition, the battery pack 100 further includes an elastic heat conducting member T that is arranged between the array 2a and the wall surface 1s. Thereby, for example, by compressing the heat conducting member T in a state where the array body 2a is curved in advance, the central portion M of the array body 2a is expanded from the wall surface 1s of the housing 1 by the expansion of the battery cells 11 with the passage of time. Even if the array 2a is deformed so as to be separated, the heat conduction member T can be restored. Therefore, it becomes difficult to form a gap between the array body 2a and the wall surface 1s without the heat conduction member T interposed therebetween, and it is possible to prevent the cooling performance of the battery cells 11 from being lowered with the passage of time.

Further, in the battery pack 100, the fastening member 4 includes the bolts 41 and 43 (first fastening member) that apply a restraining load to the wall surface 1s side of the array 2a in the array direction A of the battery cells 11, and the bolts 41 and Bolts 40 and 42 (second fastening members) that apply a restraining load to the array 2a in the array direction A of the battery cells 11 at a position farther from the wall surface 1s than the position of 43. The restraint load of the bolts 41 and 43 is smaller than the restraint load of the bolts 40 and 42. As a result, the restraint load on the wall surface 1s side becomes small, so that it becomes easy to bend the array body 2a in advance so that the central portion M of the array body 2a approaches the wall surface.

The above-described first and second embodiments describe one embodiment of the battery pack according to the present invention. Therefore, the battery pack according to the present invention is not limited to the above. The battery pack according to the present invention can be arbitrarily modified from the one described above without departing from the scope of the claims.

In the above-described embodiment, the battery pack 100 configured to radiate the heat of the battery cells 11 to the wall surface 1s of the housing 1 has been described as an example. However, as shown in FIG. Can be transformed into a battery pack 100A configured to radiate heat to the wall surface 1As of the different heat dissipation member 1A. In this case, the extending portion 15c may be arranged on the side surface 13d via the side wall portion 20c of the cell holder 20, and the heat conducting member T may be interposed between the extending portion 15c and the wall surface 1As.

In the example of FIG. 7, similarly to the example of FIG. 5, the array bodies 2a are arrayed along the array direction A2 so as to be convex toward the wall surface 1s. In the final stage of deterioration of the battery cells 11 in which the expansion amount of the battery cells 11 is large, for example, as shown in FIG. 8, the array direction A3 of the array 2a approaches the direction along the X direction again. Even in this state, as in the example of FIG. 6, since the array 2a is not substantially deformed in the array direction along the X direction, stress concentration is unlikely to occur in the fastening member 4. Therefore, even if the array body 2a is deformed so that the central portion M of the array body 2a is separated from the wall surface 1s of the housing 1 due to the expansion of the battery cells 11 with the passage of time, By comparison, the deformation of the fastening member 4 due to the deformation of the array 2a is suppressed, and it is possible to reduce the occurrence of stress concentration on the fastening member 4 in the final stage of deterioration.

Further, in the example of FIG. 8, the central portion M of the array 2a approaches the wall surface 1As of the heat dissipation member 1A as the array 2a is deformed. Therefore, it is difficult to form a gap between the array body 2a and the wall surface 1As in which the heat conduction member T is not interposed. Therefore, it is possible to prevent the cooling performance of the battery cells 11 from decreasing with the passage of time. The heat conducting member T in this case is not limited to an elastic member or a plate-like member made of a rubber material, and various heat conducting members such as liquid TIM can be adopted.

In the above embodiment, the battery cells 111 to 117 are arranged so as to be convex toward the wall surface 1s so that the battery cell 114 located in the center of the array 2a comes closest to the wall surface 1s of the housing 1. However, the present invention is not limited to this example. For example, the battery cell 113 may be closest to the wall surface 1s of the housing 1, or the battery cell 115 may be closest to the wall surface 1s of the housing 1.

Further, the heat conductive member T may be a member having an adhesive property (for example, an adhesive or the like). In this case, for example, even if the array body 2a is deformed so that the central portion M of the array body 2a is separated from the wall surface 1s of the housing 1 due to the expansion of the battery cells 11 with the passage of time, the heat conductive member T has the adhesive property. As a result, it becomes easy to maintain the state in which both the array 2a and the wall surface 1s are in contact (interface adhesion). Therefore, it becomes difficult to form a gap between the array body 2a and the wall surface 1s without the heat conduction member T interposed therebetween, and it is possible to prevent the cooling performance of the battery cells 11 from being lowered with the passage of time.

1... Casing, 1s... Wall surface, 2... Battery module, 2a... Array, 3... Fixing member, 3s... Reference surface, 4... Fastening member, 11... Battery cell, 13a, 13b... Side surface (2nd side surface), 13c... Side surface (first side surface), 30s... Restraining surface, 31s... Fixing surface, 40-43... Bolt (fastening member), M... Central part, T... Heat conducting member, 100, 100A... Battery pack.

Claims (9)

A battery pack in which a battery module is housed in a housing,
The battery module is
An array including a plurality of battery cells arranged along one direction,
A pair of fixing members arranged at the array ends of the array, and fixed to the wall surface of the housing;
A fastening member that applies a restraining load to the array in the array direction of the battery cells,
Have
Each of the pair of fixing members has a contact surface that contacts the wall surface,
Each of the plurality of battery cells has a first side surface facing a reference surface that is a single plane including the contact surfaces of the pair of fixing members ,
The plurality of battery cells are arranged so as to be convex toward the reference surface ,
The battery pack is arranged such that the angle formed by the first side surface and the reference surface becomes larger as the battery cells are arranged closer to the array end of the array body with respect to the central portion of the array body . A battery pack in which a battery module is housed in a housing,
The battery module is
An array including a plurality of battery cells arranged along one direction,
A pair of fixing members arranged at the array ends of the array, and fixed to the wall surface of the housing;
A fastening member that applies a restraining load to the array in the array direction of the battery cells,
Have
Each of the pair of fixing members has a contact surface that contacts the wall surface,
Each of the plurality of battery cells has a second side surface that intersects with the arrangement direction,
The plurality of battery cells are arranged so as to be convex toward a reference plane that is a single plane including the contact surfaces of the pair of fixing members, and the second side surfaces of the plurality of adjacent battery cells that face each other. A battery pack that is arranged such that the distance between them decreases as the distance from the reference plane increases. Each of the pair of fixing members has a constraining surface that constrains the array, and a fixing surface that is fixed to the housing,
The battery pack according to claim 1 or 2, wherein an angle formed between the constraining surface and the fixed surface on the side opposite to the array body with respect to the constraining surface is an obtuse angle. The battery pack according to any one of claims 1 to 3, further comprising a heat conducting member having elasticity arranged between the array and the wall surface. The battery pack according to claim 4, wherein the heat conductive member has an adhesive property. The battery pack according to claim 4, wherein the heat conductive member is made of a rubber material. The fastening member includes a first fastening member that applies a restraining load to the wall surface side of the array body in an arrangement direction of the battery cells, and the array is provided at a position farther from the wall surface than a position of the first fastening member. A second fastening member for applying a restraining load to the body in the arrangement direction of the battery cells,
The battery pack according to any one of claims 1 to 6, wherein the restraining load of the first fastening member is smaller than the restraining load of the second fastening member. An array including a plurality of battery cells arranged along one direction,
A pair of fixing members respectively arranged at the array ends of the array body and fixed to an external component,
A fastening member that applies a restraining load to the array in the array direction of the battery cells,
Equipped with
Each of the pair of fixing members has a contact surface that contacts the external component,
Each of the plurality of battery cells has a first side surface facing a reference surface that is a single plane including the contact surfaces of the pair of fixing members,
The plurality of battery cells are arranged so as to be convex toward the reference surface,
A battery module in which the battery cells arranged closer to the array end of the array with respect to the central portion of the array are arranged such that the angle formed by the first side surface and the reference surface is larger. An array including a plurality of battery cells arranged along one direction,
A pair of fixing members respectively arranged at the array ends of the array body and fixed to an external component,
A fastening member that applies a restraining load to the array in the array direction of the battery cells,
Equipped with
Each of the pair of fixing members has a contact surface that contacts the external component,
Each of the plurality of battery cells has a second side surface that intersects with the arrangement direction,
The plurality of battery cells are arranged so as to be convex toward a reference plane that is a single plane including the contact surfaces of the pair of fixing members, and the second side surfaces of the plurality of adjacent battery cells that face each other. A battery module, which is arranged such that the distance between them decreases as the distance from the reference plane increases.

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