JP6111788B2 - Battery pack - Google Patents

Description

  The present invention relates to a battery pack in which a battery module is fixed to an object to be joined.

  As a battery module formed by arranging a plurality of battery cells in parallel, for example, a battery assembly described in Patent Document 1 is known. The battery assembly described in Patent Document 1 is configured by arranging a plurality of single batteries (battery cells) in parallel and providing a heat transfer plate between the single batteries.

JP-A-8-148187

  By the way, when a temperature difference arises between several single batteries, the lifetime of a specific single battery will become short. In the case of a battery module in which a plurality of single batteries are arranged side by side, the heat is more likely to get closer to the center of the battery modules in the arrangement direction of the single batteries. For this reason, the single battery provided near the center in the direction in which the single batteries are arranged tends to be higher in temperature than the single battery provided in the position farthest from the center in the direction in which the single batteries are arranged. And the single battery which becomes high in temperature tends to have a short life, and the life of the entire battery module may be shortened.

  The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a battery pack capable of reducing a temperature difference between battery cells.

A battery pack that solves the above problems includes a battery module in which a plurality of battery cells are arranged side by side, an object to be joined to which the battery module is fixed, and heat conduction that is interposed between the battery module and the object to be joined. Members and brackets that are provided at both ends of the battery modules in the juxtaposed direction of the battery cells and fix the battery modules to the joined body, and the battery modules are arranged in parallel with the battery cells in the battery modules. The battery cell provided at the position closest to the center of the installation direction protrudes toward the bonded body, and the battery cell provided at the position farthest from the center of the battery module in the battery installation direction of the battery module in a state of being deflected so as to be separated from the object to be bonded is pressed against the heat conducting member by said bracket, the heat-conducting The length of the direction from the battery module in timber to the object to be bonded, by the battery module is pressed against, provided at the farthest position from the arrangement direction center of the battery cells in the battery module Compared with the portion facing the battery cell, the portion facing the battery cell provided at the position closest to the center of the battery cell in the battery module is shorter, and the heat absorption efficiency of the joined body is The battery module is provided at a position closest to the battery cell side-by-side center of the battery module compared to a portion facing the battery cell provided at a position farthest from the center of the battery cell side-by-side. Furthermore, the gist is that the portion facing the battery cell is higher.

  According to this, to-be-joined body is the position farthest from the center of the battery cell in the battery module in the battery module in the battery module. It absorbs more than the heat generated by the battery cells provided in the. For this reason, a lot of heat is absorbed by the battery cells (battery cells provided at the position closest to the center of the battery cells in the battery module in the battery module) where the heat is easily generated and the temperature is likely to be high. Can be small. The “endothermic efficiency” indicates an endothermic amount per unit time (amount of heat absorbed from the battery cell). Further, the “center in the direction in which the battery cells are arranged” means the center of a line connecting the battery cells provided at both ends in the direction in which the battery cells are arranged in the shortest distance.

  According to this, the heat | fever which the battery cell emitted is conducted to a to-be-joined body via a heat conductive member. The heat conducting member provided between the battery module and the joined body is a member for filling a gap between the battery module and the joined body and increasing a contact area between the battery module and the joined body. The heat conducting member only needs to be able to fill the gap between the battery module and the object to be joined. The shorter the length in the direction from the battery module to the object to be joined, the shorter the heat from the battery cell is conducted to the object to be joined. Cheap. The length of the heat conducting member in the direction from the battery module at the portion facing the battery cell, which is likely to be high in temperature, located closest to the center of the battery cells in the direction in which the battery cells are juxtaposed, It is shorter than the part facing the battery cell provided at the position farthest from. For this reason, the heat | fever which the battery cell provided in the position nearest to the arrangement | positioning direction center of a battery cell emits easily to a to-be-joined body. That is, the heat absorption efficiency of the part facing the battery cell provided at the position closest to the center of the battery cell in the juxtaposed direction in the joined body is improved. For this reason, the temperature difference between battery cells becomes small.

Further, the battery module, the Ru is fixed to the object to be bonded by a bracket provided in the arrangement direction of the both ends of the battery cells in the battery module.

According to this, the battery module is strongly pressed against the object to be bonded as the position is closer to the bracket, and the pressing force against the object to be bonded is weakened as the distance from the bracket is increased. For this reason, the length of the heat conducting member in the direction from the battery module to the joined body tends to be longer as the portion facing the battery cell provided at the position closest to the center of the battery cells in the juxtaposition direction. However, the portion of the joined body that faces the battery cell closest to the center of the battery cells in the juxtaposed direction protrudes toward the battery module, so that even if the applied pressure is weak, the portion to be covered from the battery module of the heat conducting member is covered. The length in the direction toward the joined body can be shortened .

  According to the present invention, the temperature difference between battery cells can be reduced.

The perspective view which shows the battery pack of 1st Embodiment. FIG. 1 is a cross-sectional view taken along line 1-1 of FIG. 1 showing the battery pack of the first embodiment. Sectional drawing which shows the battery pack of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which the battery pack is embodied will be described.
As shown in FIG. 1, the battery pack 10 has a battery module 21 housed in a rectangular box-like case 11. In the present embodiment, three battery modules 21 are stacked.

  As shown in FIG. 2, the battery module 21 is fixed to the side wall 12 of the case 11. The side wall 12 has a rectangular flat plate shape. The side wall 12 as the joined body is provided with a protruding portion 13 that protrudes toward the inside of the case 11. The protruding portion 13 is provided on the side wall 12 of the case 11 at a portion facing the battery module 21. The protruding portion 13 has the thickest central portion in the short direction of the side wall 12 and gradually decreases in thickness toward the end of the side wall 12 in the short direction.

  A battery module 21 is fixed to the side wall 12 of the case 11. The battery module 21 is fixed so that the protruding portion 13 and a part thereof face each other. The battery module 21 includes a plurality of battery cells 22 (for example, secondary batteries such as a lithium ion secondary battery and a nickel hydride storage battery) held in a resin battery holder 23. In the present embodiment, 14 battery cells 22 are arranged in parallel. In the present embodiment, the parallel direction of the battery cells 22 and the short direction of the side wall 12 are the same direction. In the following description, the battery cell 22 provided in the battery module 21 at the position closest to the center of the battery cell 22 in the juxtaposition direction is indicated by reference numeral 22A (hereinafter, the battery cell 22A provided on the innermost side). The battery cell 22 provided at the position farthest from the center of the parallel arrangement direction is denoted by reference numeral 22B (hereinafter, the battery cell 22B provided on the outermost side). Here, “the center in the direction in which the battery cells are arranged in parallel” means the center C of the line L that connects the battery cells 22 provided at both ends in the direction in which the battery cells 22 are arranged in the shortest distance. When the number of battery cells 22 arranged in parallel is an even number, the “innermost battery cell 22A” is two, and when the number is odd, the number is one. The “battery cell provided on the outermost side” can be rephrased as “a battery cell provided at an end in the direction in which the battery cells are arranged in parallel”.

  The battery module 21 is provided such that the battery cell 22 </ b> A provided on the innermost side is opposed to the central portion in the short side direction of the side wall 12 in the protruding portion 13. That is, the protruding portion 13 protrudes toward the battery module 21, and the battery module 21 has a portion facing the battery cell 22 </ b> A provided on the innermost side than a portion facing the battery cell 22 </ b> B provided on the outermost side. Protrusively toward.

  A metal (for example, aluminum) heat transfer plate 24 is interposed between the adjacent battery cells 22. In the battery module 21, end plates 25 are provided at both ends of the battery cells 22 in the juxtaposition direction. A bolt B <b> 1 is inserted through each end plate 25 and all the battery holders 23, and the bolt B <b> 1 is screwed into the nut N. A bracket 26 is fixed to the end plate 25. The bracket 26 is formed by bending a single plate material at a right angle, a rectangular plate-shaped first fixing portion 27 fixed to the end plate 25, and a rectangular plate-shaped second fixing fixed to the side wall 12. A portion 28 is provided. The 1st fixing | fixed part 27 is integrated with the end plate 25 by methods, such as welding, for example. Thereby, the bracket 26 is being fixed to the end plate 25 (battery module 21). In addition, the 1st fixing | fixed part 27 and the end plate 25 may be integrated by other methods, such as screwing the volt | bolt which penetrated the 1st fixing | fixed part 27 to the end plate 25. FIG. Further, a bolt B <b> 3 is inserted into the second fixing portion 28, and the battery module 21 is fixed to the side wall 12 by screwing the bolt B <b> 3 to the side wall 12.

  A heat conducting member 31 (Thermal Interface Material: TIM) is provided between the battery module 21 and the side wall 12 (projection 13). The heat conducting member 31 is a member having elasticity, and is formed by curing a material having fluidity, for example. The heat conducting member 31 has a length in a direction from the battery module 21 toward the side wall 12 gradually from a portion facing the battery cell 22A provided on the innermost side toward a portion facing the battery cell 22B provided on the outermost side. Is getting longer. That is, in the heat conducting member 31, the length of the portion facing the battery cell 22A is shorter in the direction from the battery module 21 toward the side wall 12 than the portion facing the battery cell 22B.

  In addition, when it is desired to improve the heat transfer efficiency from the battery cell 22 to the side wall 12, ideally, the heat conducting member 31 is not provided, and the battery module 21 and the side wall 12 are preferably in contact with each other without any gap. However, since there is a slight gap between the battery module 21 and the side wall 12 due to manufacturing errors and the like, the heat conducting member 31 is provided to fill this gap. When the heat conducting member 31 is provided, the heat transfer efficiency from the battery module 21 to the side wall 12 is improved by shortening the length of the heat conducting member 31 in the direction from the battery module 21 toward the side wall 12.

Next, the operation of the battery pack 10 of this embodiment will be described.
In the present embodiment, the heat conducting member 31 has a short length in the direction from the battery module 21 toward the side wall 12 at the portion facing the battery cell 22A provided on the innermost side, and faces the battery cell 22B provided on the outermost side. The length in the direction from the battery module 21 toward the side wall 12 gradually increases as it approaches the portion. In the battery module 21 in which a plurality of battery cells 22 are arranged side by side, the temperature of the battery cell 22 that is closer to the center of the battery cell 22 in the direction in which the battery cells 22 are arranged tends to increase. The heat conducting member 31 has a shorter length in the direction from the battery module 21 toward the side wall 12 as the portion facing the innermost battery cell 22A where the temperature is most likely to rise, so the battery provided on the innermost side. The heat is more easily absorbed by the side wall 12 as the cell 22A. That is, in the side wall 12, the portion facing the battery cell 22 </ b> A provided on the innermost side absorbs heat from the battery module 21 most.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The length of the heat conducting member 31 in the direction from the battery module 21 to the side wall 12 is opposed to the battery cell 22A provided on the innermost side, as compared with the portion facing the battery cell 22B provided on the outermost side. The part to do is shorter. For this reason, the heat generated by the battery cell 22 </ b> A that tends to increase in temperature tends to be conducted to the side wall 12. That is, in the side wall 12, the endothermic efficiency of the portion facing the battery cell 22A provided on the innermost side is higher than the endothermic efficiency of the portion facing the battery cell 22B provided on the outermost side. Therefore, the temperature difference between the battery cells 22 can be reduced. The “endothermic efficiency” refers to the amount of heat absorbed per predetermined time (the amount of heat absorbed from the battery cells 22).

  (2) The side wall 12 is provided with a protruding portion 13. The protrusion 13 has the largest protrusion amount toward the battery cell 22A. That is, the protruding portion 13 has a portion facing the battery cell 22A larger than the protruding amount of the portion facing the battery cell 22B. For this reason, it is easy to shorten the length of the heat conductive member 31 in the direction from the battery module 21 to the side wall 12 at the portion facing the battery cell 22A.

  (3) The battery module 21 is fixed by the bracket 26. When the battery modules 21 are fixed by the brackets 26 provided at both ends of the battery cells 22 in the juxtaposed direction, the pressing force pressing the battery modules 21 against the side walls 12 becomes weaker as the battery cells 22 are farther from the brackets 26. That is, the pressing force becomes weaker as the battery cell 22 is closer to the battery cell 22A, the length in the direction from the battery module 21 to the side wall 12 of the portion of the heat conducting member 31 facing the battery cell 22A is the longest, and the battery cell 22B. The length in the direction from the battery module 21 to the side wall 12 at the portion facing the surface is likely to be the shortest. By providing the protruding portion 13, it is easy to shorten the length of the portion of the heat conducting member 31 facing the battery cell 22 </ b> A in the direction from the battery module 21 toward the side wall 12. For this reason, even if the battery module 21 is fixed by the brackets 26 provided at both ends of the battery cell 22 in the juxtaposed direction, the length of the heat conducting member 31 facing the battery cell 22A in the direction from the battery module 21 toward the side wall 12 is long. Easy to shorten.

  (4) Moreover, as for the thickness of the side wall 12, the part facing 22 A of battery cells provided in the innermost part is thicker than the part facing battery cell 22 B provided in the outermost part. For this reason, the heat capacity of the portion facing the battery cell 22A is larger than that of the portion facing the battery cell 22B, and the heat absorption efficiency is improved. Therefore, the temperature difference between the battery cells 22 can be further reduced.

(Second Embodiment)
Hereinafter, a second embodiment in which the battery pack is embodied will be described. In the following description, description of parts that are the same as those of the first embodiment will be omitted, and only parts that are different from the first embodiment will be described.

  As shown in FIG. 3, the battery module 41 of the present embodiment is fixed to the side wall 42. The side wall 42 has a uniform thickness over the entire short direction. That is, the protrusion 13 in the first embodiment is not provided. In the side wall 42, plate-like fins 44 are provided on the surface opposite to the surface on which the battery module 41 is fixed (the outer surface of the case 11). The fins 44 on the side wall 42 are formed between the notches 43 by forming a plurality of notches 43 in the lateral direction of the side wall 42 by notching the side walls 42 in the thickness direction. The fins 44 are provided so as to include portions facing the battery cells 22A. On the other hand, the fin 44 is not provided in the part facing the battery cell 22B. In the present embodiment, the heat conducting member 45 provided between the battery module 21 and the side wall 42 has a uniform length in the direction from the battery module 41 toward the side wall 42.

Next, the operation of the battery pack 10 of this embodiment will be described.
The side wall 42 absorbs heat generated by the battery cell 22. The side wall 42 radiates heat absorbed from the battery cell 22 by exchanging heat with air or the like existing outside the case 11. At this time, the heat radiation efficiency of the side wall 42 can be improved by increasing the heat radiation area by the fins 44. Therefore, the heat dissipation efficiency of the portion where the fins 44 are provided can be partially improved. By improving the heat dissipation efficiency of the portion where the fins 44 are provided, the temperature of the portion where the fins 44 are provided is likely to decrease, and as a result, the heat generated by the battery cells 22 is easily absorbed. Therefore, in the portion where the fins 44 are provided, the amount of heat absorbed per predetermined time (the amount of heat absorbed from the battery cells 22) is improved.

  In the present embodiment, the fins 44 are provided so as to include portions facing the battery cells 22A. On the other hand, the fin 44 is not provided in the part facing the battery cell 22B. Therefore, the side wall 42 absorbs more heat generated by the battery cell 22A than heat generated by the battery cell 22B.

Therefore, according to the above embodiment, the following effects can be obtained.
(5) The endothermic efficiency of the portion facing the battery cell 22A on the side wall 42 is made higher than the endothermic efficiency of the portion facing the battery cell 22B. For this reason, the side wall 42 absorbs more heat of the battery cell 22A than the heat of the battery cell 22B. Therefore, the temperature difference between the battery cells 22 can be reduced.

In addition, you may change embodiment as follows.
In each embodiment, the battery module 23 may be configured by modularizing only the battery cell 22 without providing the battery holder 23 or the heat transfer plate 24.

  -In each embodiment, you may employ | adopt other than the side walls 12 and 42 as a to-be-joined body. For example, it may be a bottom plate or a top plate of the case 11 or a counterweight mounted on a forklift.

  In each embodiment, the method for fixing the battery modules 21 and 41 may be changed. For example, the bracket 26 may be provided at an end portion in a direction orthogonal to the parallel arrangement direction of the battery cells 22. Further, a member that presses the battery modules 21 and 41 toward the side walls 12 and 42 may protrude from the side walls facing the side walls 12 and 42, thereby fixing the battery modules 21 and 41.

In each embodiment, the number of battery modules 21 may be changed as appropriate. The number of battery modules 21 may be single.
(Circle) in 1st Embodiment, the protrusion part 13 does not need to be provided. In this case, by bending the battery module 21, the battery module 22 is configured such that the battery cell 22A protrudes toward the side wall 42 and the battery cell 22B is separated from the side wall 42. Then, when the battery module 21 is fixed to the side wall 42, the pressing force to the heat conducting member 45 increases as the part faces the battery cell 22A having a larger amount of protrusion toward the side wall 42. Thereby, as for the heat conductive member 45, the length of the direction facing the battery cell 22A from the battery module 21 toward the side wall 12 becomes shorter than the part facing the battery cell 22B.

  In the second embodiment, the side wall 42 is increased by increasing the heat capacity of the portion facing the battery cell 22A, such as increasing the volume of the portion facing the battery cell 22A to be larger than the volume of the portion facing the battery cell 22B. The endothermic efficiency of the portion facing the battery cell 22A may be higher than the endothermic efficiency of the portion facing the battery cell 22B.

In the second embodiment, the fins 44 are formed by cutting out the side walls 42, but the fins 44 may be erected in the thickness direction of the side walls 42 without cutting out the side walls 42.
In the second embodiment, by increasing the depth of the notch 43 from the portion facing the battery cell 22A on the side wall 42 toward the portion facing the battery cell 22B, the portion facing the battery cell 22B The closer the fin 44, the larger the heat radiation area may be.

In the second embodiment, the heat conducting member 45 may not be provided.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) The heat radiation area of the joined body is closest to the center of the battery cells in the juxtaposition direction compared to the portion facing the battery cell provided at the position farthest from the center of the battery cells in the juxtaposition direction. The battery pack according to claim 1, wherein a portion facing the battery cell provided at a position is larger.

  DESCRIPTION OF SYMBOLS 10 ... Battery pack, 12, 42 ... Side wall, 13 ... Projection part, 21, 41 ... Battery module, 22 ... Battery cell, 26 ... Bracket, 31, 45 ... Heat conduction member.

Claims (1)

A battery module having a plurality of battery cells arranged in parallel;
A joined body to which the battery module is fixed;
A heat conducting member interposed between the battery module and the joined body ;
Provided at both ends of the battery cells in the battery module in the juxtaposed direction, and a bracket for fixing the battery module to the joined body ,
In the battery module, the battery cell provided at the position closest to the center of the battery cell in the battery module in the juxtaposition direction protrudes toward the joined body, and the battery cell is juxtaposed in the battery module. In a state where the battery cell provided at the position farthest from the center is bent so as to be separated from the object to be joined, the battery cell is pressed against the heat conducting member by the bracket,
The length of the heat conducting member in the direction from the battery module to the bonded body is the farthest from the center of the battery modules in the juxtaposed direction when the battery module is pressed. Compared with the portion facing the battery cell provided, the portion facing the battery cell provided in the position closest to the center of the battery cell in the battery module in the parallel arrangement direction is shorter,
The heat absorption efficiency of the joined body is such that the battery cells in the battery module are arranged side by side as compared with the portion facing the battery cell that is provided farthest from the center in the battery cell arrangement direction in the battery module. A battery pack characterized in that a portion facing the battery cell provided at a position closest to the center in the direction is higher.