JP2014110218A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce difference in temperature between secondary batteries, while suppressing increase in the number of components.SOLUTION: In a battery module 50, rectangular batteries 51A-51D are aligned in a state of being held in a battery holder 52, and heat-transfer plates 53A-53D are aligned such that the rectangular batteries 51A-51D and the heat-transfer plates 53A-53D are alternately arranged. A surface opposite to a surface facing a second coated portion 63 of a heat radiation part 72 of the heat-transfer plates 53A-53D surface-contact with a weight main body 33. In an alignment direction of the rectangular batteries 51A-51D, the heat-transfer plate 53A has the least area of contact with the weight main body 33 of the heat-transfer plate 53A joined to the rectangular battery 51A provided at the most distal end, and the heat-transfer plate 53B has the next least area of contact after the heat-transfer plate 53A. The heat-transfer plate 53C has the next least area of contact with the weight main body 33 after the heat-transfer plate 53B, and the heat-transfer plate 53D joined to the rectangular battery 51D has the largest area of contact with the weight main body 33.

Description

  The present invention relates to a battery module that radiates heat generated by a secondary battery to a radiator.

  In the battery module, a plurality of secondary batteries are arranged in parallel. At this time, if a temperature difference occurs between the plurality of secondary batteries, the lifetime of the specific secondary battery is shortened. In the battery system described in Patent Document 1, a plurality of secondary batteries (battery cells) are arranged in parallel, and a separator is provided between secondary batteries adjacent in the arrangement direction.

  A temperature difference occurs between the secondary batteries depending on the arrangement position. A separator can change thermal resistance by making it into the shape from which thickness differs. And in the battery system of patent document 1, while forming the separator pinched | interposed into a secondary battery with high temperature thickly, while forming the separator pinched | interposed into a secondary battery with low temperature thinly, it is between secondary batteries. The temperature difference is reduced.

JP 2010-272378 A

  By the way, when the thickness of the separator is changed depending on the temperature of the secondary battery, a difference occurs in the distance between the secondary batteries between the secondary battery adjacent to the thick separator and the secondary battery adjacent to the thin separator. If there is a difference in the distance between the secondary batteries, there will also be a difference in the distance between the terminals of the adjacent secondary batteries. As a result, it is necessary to use multiple connecting members according to the distance between the terminals, increasing the number of parts. Resulting in.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a battery module capable of reducing a temperature difference between secondary batteries while suppressing an increase in the number of parts. It is to provide.

  A battery module that solves the above-described problem includes a plurality of heat transfer plates having a plurality of secondary batteries arranged side by side, a heat radiating portion facing the heat radiating body, and an inter-battery portion provided between the plurality of secondary batteries. And a plurality of connection members that connect the terminals of the secondary battery, and the inter-battery portions of the plurality of heat transfer plates absorb the heat of the secondary battery, The lengths of the plurality of secondary batteries in the side-by-side direction are the same, and the heat dissipating part of the plurality of heat transfer plates dissipates heat from the inter-battery part to the heat radiating body, and the plurality of heat transfer plates Includes a heat transfer plate having a different heat dissipation efficiency of the heat dissipation portion.

  According to this, the heat-transfer plate which has the thermal radiation part of the thermal radiation efficiency corresponding to the temperature of the secondary battery can be arrange | positioned between secondary batteries. In the battery module, since the secondary batteries are provided together, even if each secondary battery generates heat in the same way, the temperature of the secondary battery is not always the same. Moreover, since the secondary battery is also affected by the surrounding environment, there is a possibility that the temperature of the secondary battery may be biased. A temperature difference between the secondary batteries can be reduced by providing a heat transfer plate having a heat radiating portion having a heat radiation efficiency corresponding to the temperature of the secondary battery so as to be adjacent to the secondary battery. In addition, since the temperature difference between the secondary batteries can be reduced by changing the heat dissipation efficiency of the heat dissipation part, the temperature difference between the secondary batteries can be reduced by changing the length of the secondary batteries in the parallel arrangement direction between the batteries. There is no need to make it smaller. For this reason, it is possible to make the lengths of the secondary batteries in the juxtaposed direction in the inter-battery portion the same, and it is difficult for a difference in the distance between the secondary batteries to occur. Therefore, a difference in the distance between terminals of adjacent secondary batteries hardly occurs, and the secondary batteries can be connected using a common connecting member. For this reason, the increase in the number of parts is suppressed.

  Regarding the battery module, among the heat transfer plates, the inter-battery portion of the heat transfer plate having a heat dissipation portion with high heat dissipation efficiency compared to the heat dissipation efficiency of the heat dissipation portion of the other heat transfer plate is the plurality of secondary batteries. Among these, it is preferable to be provided between secondary batteries other than the secondary battery located at the end in the juxtaposition direction of the plurality of secondary batteries.

  According to this, the plurality of secondary batteries arranged in parallel are less likely to be cooled due to the heat generated by the surrounding secondary batteries as they are separated from the secondary battery located at the end. Therefore, by providing the heat transfer plate of the heat dissipation part with high heat dissipation efficiency between the secondary batteries that are difficult to be cooled, the secondary battery located at the end is adjacent to the heat transfer plate of the heat dissipation part with high heat dissipation efficiency. The temperature difference of the secondary battery can be reduced.

  About the said battery module, it may have that the thermal radiation part of high thermal radiation efficiency has heat capacity larger than the thermal capacity of the thermal radiation part of said other heat-transfer plate compared with the thermal radiation efficiency of the thermal radiation part of said other heat-transfer plate. preferable.

According to this, by increasing the heat capacity of the heat radiating portion, the heat radiating efficiency of the heat radiating portion can be increased.
About the said battery module, compared with the thermal radiation efficiency of the thermal radiation part of the said other heat-transfer plate, the thermal radiation part with high thermal radiation efficiency has a larger contact area with the said heat sink than the thermal radiation part of the said other heat-transfer plate. preferable.

  According to this, by increasing the contact area between the heat dissipating part and the heat dissipating body, the amount of heat dissipated to the heat dissipating body can be increased, thereby increasing the heat dissipating efficiency of the heat dissipating part.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature difference between secondary batteries can be made small, suppressing the increase in a number of parts.

The schematic side view which shows the forklift of embodiment. The perspective view which shows the battery pack of embodiment. The perspective view which shows the battery module of embodiment. The disassembled perspective view which shows the battery holder of embodiment, a square battery, a heat-transfer plate, and an end plate. Sectional drawing which shows the battery module of embodiment.

  Hereinafter, an embodiment in which the battery module is embodied in a battery module mounted on a forklift will be described. In the following description, “front”, “rear”, “left”, “right”, “upper”, and “lower” are “front”, “rear”, and “left” when the forklift driver is facing the front of the forklift. ”,“ Right ”,“ upper ”, and“ lower ”.

  As shown in FIG. 1, drive wheels 12 are provided at the front lower part of the vehicle body 11 of the forklift 10, and steering wheels 13 are provided at the rear lower part of the vehicle body 11. In addition, a cargo handling device is provided at the front portion of the vehicle body 11. The mast 14 constituting the cargo handling apparatus is erected on the front portion of the vehicle body 11, and the mast 14 is provided with a pair of left and right forks 16 via a lift bracket 15. The fork 16 is lifted and lowered together with the lift bracket 15 by driving a lift cylinder 17 connected to the mast 14. Further, the fork 16 is tilted together with the mast 14 by driving a tilt cylinder 18 connected to the mast 14. A load 19 is mounted on the fork 16. The vehicle body 11 is equipped with a traveling motor M1 as a drive source for the drive wheels 12 and a cargo handling motor M2 as a drive source for the fork 16.

  A cab 20 is provided in the center of the vehicle body 11. The cab 20 is provided with a driving seat 21 on which an operator (driver) can sit. A handle 22 is provided in front of the driving seat 21. A battery pack 30 is mounted below the cab 20. Hereinafter, the battery pack 30 will be described in detail.

  As shown in FIG. 2, the battery pack 30 includes a counterweight 31 for balancing with the load 19 mounted on the fork 16. The counterweight 31 is erected in the thickness direction of the weight portion 32 from the weight portion 32 having a rectangular parallelepiped shape, and the one end 32a in the lateral direction of the weight portion 32, and the other end in the longitudinal direction from the longitudinal one end 32c of the weight portion 32 The weight main body 33 has a rectangular plate shape extending over 32d. In other words, the weight portion 32 is erected from the base end of the weight body 33 in the thickness direction of the weight body 33. At the distal end of the weight body 33 (the end opposite to the base end of the weight body 33), a notch 35 is formed by cutting the weight body 33 in the thickness direction of the weight body 33. In the present embodiment, the counterweight 31 is made of a metal material such as iron, for example.

  An inverted U-shaped frame 41 that is spaced apart from the weight main body 33 is erected from the weight portion 32 at the other end 32 b in the short direction of the weight portion 32. The frame 41 includes a first pillar portion 43 and a second pillar portion 44 erected from two corners of the other end 32b in the lateral direction on the upper surface of the weight portion 32 (the surface on which the weight main body 33 is provided) , And a base portion 42 that connects the upper end portions of the first column portion 43 and the second column portion 44 (the end portion opposite to the end portion joined to the weight portion 32). That is, the battery pack 30 has a front opening 30 a surrounded by the weight 32 and the frame 41 on the other end 32 b side of the weight 32. In the battery pack 30, the front opening 30a is closed by a lid member 46 having a rectangular plate shape.

  The length in the standing direction of each pillar portion 43, 44 (the length in the longitudinal direction of each pillar portion 43, 44) is the same as the shortest length from the upper surface of the weight portion 32 to the distal end surface of the weight body 33. A top plate 47 is supported on the upper surface of the frame 41 (the upper surface of the base portion 42) and the distal end surface of the weight body 33. The top plate 47 closes an opening (not shown) between the weight body 33 and the frame 41. Further, the battery pack 30 has a weight main body 33, the weight portion 32, the first column portion 43, and one end side opening 30 b surrounded by the top plate 47 on the one end 32 c side of the weight portion 32 in the longitudinal direction. . Further, the battery pack 30 has the other end side opening 30c surrounded by the weight main body 33, the weight portion 32, the second column portion 44, and the top plate 47 on the other end 32d side of the weight portion 32 in the longitudinal direction. Have The one end side opening 30b and the other end side opening 30c are closed by a lid member 45.

  One end surface in the thickness direction of the weight main body 33 is an installation surface 33a on which the battery module 50 is installed. A plurality of battery modules 50 are provided on the installation surface 33a. Two battery modules 50 are provided side by side in the longitudinal direction of the weight main body 33, and three sets of battery modules 50 are provided side by side in the lateral direction of the weight main body 33 at intervals. A mounting plate 36 having a rectangular flat plate shape is fixed to the notch 35. On the mounting plate 36, a housing case 37 that houses a control device that controls the battery module 50 and a junction box 38 that houses a relay, wiring, and the like are disposed.

  As shown in FIGS. 3 and 4, the battery module 50 is juxtaposed in a state where a square battery 51 as a secondary battery (for example, a lithium ion secondary battery or a nickel hydride storage battery) is held by a battery holder 52. In addition, heat transfer plates 53 are arranged in parallel with the square batteries 51. In the battery module 50, end plates 54 are provided at both ends of the prismatic battery 51 in the juxtaposition direction. The prismatic battery 51 is arranged so that the polarities of the terminals 56 adjacent in the juxtaposition direction are different. The terminals 56 adjacent to each other in the juxtaposed direction are alternately connected by connection members 67 (bus bars), and the respective square batteries 51 are connected in series.

  As shown in FIG. 4, the battery holder 52 includes a square box-shaped holder main body 60 and a rectangular parallelepiped mounting base 61 provided at the four corners of the outer surface of the holder main body 60. More specifically, the holder body 60 has a first covering portion 62 that covers the surface in the thickness direction of the prismatic battery 51 while forming a rectangular plate shape. Second covering portions that cover the surfaces of the rectangular batteries 51 in the width direction (directions perpendicular to the thickness direction and the height direction of the rectangular batteries 51) are provided at both longitudinal ends 62 a and 62 b of the first covering portion 62. 63 and a third covering portion 64 are erected in the thickness direction of the first covering portion 62. Both the 2nd coating | coated part 63 and the 3rd coating | coated part 64 have comprised the rectangular plate shape. The short direction of the second covering portion 63 and the third covering portion 64 is the same direction as the thickness direction of the first covering portion 62. The dimension in the short direction of the second covering portion 63 is slightly smaller than that of the third covering portion 64.

  A fourth covering portion 65 and a fifth covering portion 66 that cover the surface in the height direction of the prismatic battery 51 are provided upright at both ends 62 c and 62 d in the short direction of the first covering portion 62. Both the 4th coating | coated part 65 and the 5th coating | coated part 66 have comprised the rectangular plate shape. The longitudinal directions of the fourth covering portion 65 and the fifth covering portion 66 are the same as the longitudinal direction of the first covering portion 62. The short direction of the fourth covering portion 65 and the fifth covering portion 66 is the same direction as the thickness direction of the first covering portion 62. The dimension in the short direction of the fifth covering portion 66 is slightly smaller than that of the fourth covering portion 65.

  Mounts 61 are provided on the outer surfaces of the longitudinal ends of the fourth covering portion 65 and the fifth covering portion 66. Each mounting base 61 is provided with an insertion hole 61a through which the bolt B1 is inserted.

  The holder main body 60 has a housing portion S in which the square battery 51 is housed in a region surrounded by the covering portions 62 to 66. And while the square battery 51 is accommodated in this accommodating part S, it heat-transfers to the surface side on the opposite side to the surface coat | covered with the 1st coating | coated part 62 among the thickness direction both surfaces of the square battery 51. A plate 53 is provided.

  The heat transfer plate 53 has a rectangular plate shape and is joined to the surface in the thickness direction of the prismatic battery 51, and a rectangular plate shape that extends in the thickness direction of the main body portion 71 from one longitudinal end 71a of the main body portion 71. The heat radiating part 72 is provided. The main body portion 71 and the heat radiating portion 72 are different in the short side direction and the long side direction. The heat transfer plate 53 is made of a metal such as aluminum, for example. In the heat transfer plate 53, the main body 71 is joined to the surface in the thickness direction of the rectangular battery 51, and the heat radiating portion 72 protrudes out of the battery holder 52 so that the outer surface of the second covering portion 63 (second covering portion). 63, the surface opposite to the surface facing the third covering portion 64).

  The end plate 54 has a main body portion 74 having a rectangular plate shape, and attachment portions 75 provided at four corners of the main body portion 74. The attachment portion 75 is provided with an insertion hole 75a through which the bolt B1 is inserted. The battery module 50 is configured such that the bolt B1 is inserted into the insertion hole 75a provided in the attachment base 75 of the battery holder 52 and the attachment portion 75 of the end plate 54, and the bolt B1 has a nut. N is fixed by screwing.

  As shown in FIG. 5, in the battery module 50, the bolt B <b> 2 inserted through the bracket 76 provided on the surface opposite to the surface facing the battery module 50 in the end plate 54 is screwed into the weight body 33. The weight main body 33 is fixed. At this time, in the heat radiating portion 72 of the heat transfer plate 53, the surface opposite to the surface facing the second covering portion 63 is in surface contact with the weight main body 33.

  In the battery module 50 of the present embodiment, the size of the heat radiating portion 72 of the heat transfer plate 53 is different. In the battery module 50 shown in FIG. 5, for convenience of explanation, the rectangular battery 51 provided at the extreme end (both ends) in the side-by-side direction of the battery module 50 is denoted by reference numeral 51 </ b> A and is adjacent to the rectangular battery 51 </ b> A. 51 is denoted by reference numeral 51B. Furthermore, reference numeral 51C is given to the square battery 51 adjacent to the opposite side of the square battery 51A in the square battery 51B, and reference numeral 51D is assigned to the square battery 51 adjacent to the opposite side of the square battery 51B in the square battery 51C. Is attached. The prismatic battery 51D is a prismatic battery that is disposed at a position closest to the center C of the line L that connects both ends of the prismatic batteries 51 in the battery module 50 in the juxtaposition direction. In addition, the heat transfer plates 53 joined to the surfaces in the thickness direction of the respective square batteries 51A, 51B, 51C, 51D will be described with reference numerals 53A, 53B, 53C, 53D, respectively. Note that the square batteries 51A to 51D have the same heat generation amount during discharging or charging.

  Each of the heat transfer plates 53A to 53D has a length in the longitudinal direction of the main body 71, a dimension in the short direction, and a thickness (the length in the parallel arrangement direction of the prismatic batteries 51 in the main body 71 of the heat transfer plates 53A to 53D. ) Are the same. The main body 71 is an inter-battery portion provided between the respective square batteries 51A to 51D.

  Each of the heat transfer plates 53 </ b> A to 53 </ b> D has different dimensions in the short direction of the heat radiating portion 72. Specifically, the heat sink 72 has the largest dimension in the short direction of the heat transfer plate 53D, the heat sink 72 of the heat transfer plate 53C next to the heat sink 72 of the heat transfer plate 53D. . Further, the heat dissipation portion 72 has a short dimension in the short direction, the heat dissipation portion 72 of the heat transfer plate 53B being next to the heat dissipation portion 72 of the heat transfer plate 53C, and the heat dissipation portion 72 of the heat transfer plate 53A being the smallest. In addition, the dimension of the longitudinal direction of the thermal radiation part 72 is the same in all the heat-transfer plates 53A-53D. The heat dissipation portions 72 of the heat transfer plates 53A to 53D have different heat capacities due to the different dimensions in the short direction.

  In the parallel arrangement direction of the square batteries 51, the heat transfer plate 53 </ b> A joined to the square battery 51 </ b> A provided at the end has the smallest heat capacity of the heat radiating portion 72. The heat transfer plate 53B joined to the prismatic battery 51B has the heat capacity of the heat radiating portion 72 next to the heat capacity of the heat radiating portion 72 of the heat transfer plate 53A. In the heat transfer plate 53C joined to the square battery 51C, the heat capacity of the heat dissipating part 72 is next to the heat capacity of the heat dissipating part 72 of the heat transfer plate 53B. The heat transfer plate 53D joined to the prismatic battery 51D has the largest heat capacity of the heat radiating portion 72.

  Furthermore, the contact area of each heat-transfer plate 53A-53D and the weight main body 33 differs because the length of the heat radiation part 72 in the transversal direction differs. The contact areas of the heat transfer plates 53A to 53D increase as they approach the heat transfer plate 53D from the heat transfer plate 53A at the end (both ends) in the side-by-side arrangement of the prismatic batteries 51. That is, in the parallel arrangement direction of the square batteries 51, the heat transfer plate 53A joined to the square battery 51A provided at the end has a smaller contact area with the weight body 33.

  In the direction in which the prismatic batteries 51 are arranged side by side, the heat transfer plate 53A joined to the prismatic battery 51A provided at the end has the smallest contact area with the weight main body 33 of the heat radiating section 72. The heat transfer plate 53B joined to the prismatic battery 51B has a contact area with the weight main body 33 of the heat radiating portion 72 next to the contact area with the weight main body 33 of the heat radiating portion 72 of the heat transfer plate 53A. The heat transfer plate 53C joined to the square battery 51C has the contact area with the weight main body 33 of the heat radiating portion 72 next to the contact area with the weight main body 33 of the heat radiating portion 72 of the heat transfer plate 53B. The heat transfer plate 53D joined to the square battery 51D has the largest contact area with the weight main body 33 of the heat radiating portion 72.

  And as for the thermal radiation part 72 of heat-transfer plate 53A-53D, the thermal radiation efficiency becomes high, so that the contact area with the weight main body 33 is large. Moreover, the heat dissipation part 72 of the heat transfer plates 53A to 53D has higher heat dissipation efficiency as the heat capacity is larger. For this reason, the heat dissipation efficiency increases in the order of the heat dissipating part 72 of the heat transfer plate 53D> the heat dissipating part 72 of the heat transfer plate 53C> the heat dissipating part 72 of the heat transfer plate 53B> the heat dissipating part 72 of the heat transfer plate 53A. That is, the heat dissipation efficiency of the heat dissipation portion 72 of the heat transfer plate 53D is higher than the heat dissipation efficiency of the heat dissipation portions 72 of the other heat transfer plates 53A to 53C. And the main-body part 71 of the heat-transfer plate 53D is between the square battery 51C and the square battery 51D which are square batteries 51 other than the square battery 51A located in the endmost in the parallel arrangement direction of the square batteries 51. Is provided.

Next, the operation of the battery module 50 will be described.
When each of the square batteries 51A to 51D generates heat, this heat is diffused to the surroundings via the battery holder 52 and the heat transfer plates 53A to 53D. Of the heat transfer plates 53A to 53D, heat is conducted from both the square batteries 51A to 51D sandwiching the main body 71 to the main body 71 of the heat transfer plates 53A to 53D sandwiched between the square batteries 51A to 51D. . Heat is conducted from the prismatic battery 51A to the heat transfer plate 53A that is not sandwiched between the prismatic batteries 51A to 51D.

  The heat diffused to the battery holder 52 and the heat transfer plates 53A to 53D is radiated to the weight body 33 and the surrounding heat medium. Therefore, the counterweight 31 (the weight main body 33) functions as a heat radiating body that radiates heat generated by the square batteries 51A to 51D. The prismatic battery 51D provided at a position closest to the center C of the line L is likely to generate heat. On the other hand, in the direction in which the square batteries 51 are arranged side by side, the square battery 51A provided at the end is hardly affected by the surrounding square batteries 51B to 51D. As a result, when the calorific values at the time of discharging or charging of the square batteries 51A to 51D are the same, the temperature may increase in the order of the square battery 51A> the square battery 51B> the square battery 51C> the square battery 51D. high.

  In the heat transfer plates 53A to 53D, the heat dissipation efficiency of the heat radiating part 72 is larger in the order of heat transfer plate 53D> heat transfer plate 53C> heat transfer plate 53B> heat transfer plate 53A. As the heat transfer plates 53A to 53D joined to the square batteries 51A to 51D having higher temperatures increase the heat dissipation efficiency, the temperature difference between the square batteries 51 becomes smaller.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The heat transfer plates 53 </ b> A to 53 </ b> D reduce the temperature difference between the square batteries 51 </ b> A to 51 </ b> D by making the heat dissipation efficiency of the heat dissipation part 72 different. In particular, in this embodiment, the temperature of the square battery 51 becomes uniform by using the heat transfer plates 53A to 53D corresponding to the temperature of the square batteries 51A to 51D. Even if the heat transfer plates 53A to 53D have the same thickness (the length in the direction in which the prismatic batteries 51A to 51D are arranged in parallel), the temperature difference between the prismatic batteries 51A to 51D can be reduced. The distances between the batteries 51 </ b> A to 51 </ b> D are equal, and the square batteries 51 </ b> A to 51 </ b> D can be connected by the common connection member 67. For this reason, it is not necessary to prepare a plurality of connecting members according to the distance between the square batteries 51, and an increase in the number of parts is suppressed.

  (2) The heat capacity of the heat radiating portion 72 of each of the heat transfer plates 53A to 53D is made different by changing the dimension in the short direction of the heat radiating portion 72 of each of the heat transfer plates 53A to 53D. And the thermal radiation efficiency of each heat-transfer plate 53A-53D can be varied by varying the heat radiation amount of each heat-transfer plate 53A-53D.

  (3) The contact area between the heat radiating portion 72 of each of the heat transfer plates 53A to 53D and the weight main body 33 varies depending on the amount of heat generated by the square batteries 51A to 51D. For this reason, the heat radiation efficiency of the heat radiation part 72 can be varied depending on the contact area with the weight main body 33.

  (4) When the square battery 51 and the heat transfer plate 53 are supported by the battery holder 52 as in the battery module 50 of the present embodiment, the thickness of the separator between the secondary batteries is set as described in Patent Document 1. If changed, it is necessary to change the shape of the battery holder 52 in accordance with the thickness of the separator. For this reason, a plurality of battery holders are required, and the number of parts may increase. As in this embodiment, it is not necessary to change the shape of the battery holder 52 by increasing the contact area of the weight body 33 and making the thickness of the portion sandwiched between the square batteries 51 of the heat transfer plate 53 uniform. . For this reason, the temperature difference between the square batteries 51 can be reduced without increasing the number of parts.

In addition, you may change embodiment as follows.
In the embodiment, the heat capacity of the heat dissipating part 72 may be varied by varying the thickness of the heat dissipating part 72 of each heat transfer plate 53, thereby varying the heat dissipating efficiency of the heat dissipating part 72.

  In the embodiment, the heat dissipation efficiency of the heat dissipating part 72 may be varied by changing the material of the heat dissipating part 72 of each heat transfer plate 53. Further, in addition to the heat radiating portion 72, the material of the main body portion 71 may be different.

  In the embodiment, the contact area with the weight main body 33 is made different by changing the dimension in the short direction of the heat radiating portion 72 of each heat transfer plate 53, but is not limited thereto. For example, the contact area with the weight main body 33 may be varied by providing the heat radiating portions 72 of some of the heat transfer plates 53 apart from the weight main body 33.

  In the embodiment, the heat transfer plates 53A to 53D having the heat radiation portions 72 having the heat radiation efficiency corresponding to the heat generation amounts of the respective square batteries 51A to 51D are joined to the respective square batteries 51A to 51D. . For example, the heat dissipation efficiency of the heat dissipating part 72 of the heat transfer plates 53A and 53D joined to the square battery 51A and the square battery 51D with the largest temperature difference is greater than the heat dissipating efficiency of the heat dissipating part 72 of the heat transfer plate 53A. It is sufficient that the heat transfer efficiency of the heat transfer plate 53D is higher, and the heat transfer efficiency of the other heat transfer plates 53 is not limited. In this case, since the temperature difference between the prismatic battery 51A and the prismatic battery 51D having the largest temperature difference is reduced, the temperature difference between the prismatic batteries 51 is reduced.

  In the embodiment, a rectangular fan 51 may be provided to cool the prismatic battery 51 with the blower. In this case, a temperature difference occurs between the prismatic battery 51 that is easily cooled by the air blown by the blower and the prismatic battery 51 that is difficult to cool. For example, when the square battery 51 located on the upstream side in the blowing direction of the blower is more easily cooled by blowing, and the square battery 51 located on the downstream side is less likely to be cooled by blowing, the square battery 51 located on the upstream side A temperature difference is generated in the square battery 51 located on the downstream side. In this case, the heat radiation efficiency of the heat radiation portion 72 of the heat transfer plate 53 joined to the square battery 51 located on the downstream side is made higher than that of the other heat transfer plates 53. That is, when the temperature difference is biased due to an external factor such as a blower, the heat dissipation efficiency of the heat dissipation portion 72 of the heat transfer plate 53 may be varied in consideration of these.

  In the embodiment, when the heat transfer plate having the same heat dissipation efficiency is provided, the heat transfer plate 53 having the heat dissipation portion 72 having the high heat dissipation efficiency is joined to the square battery 51 other than the square battery 51 having the lowest temperature. You may let them.

  In the embodiment, the prismatic battery 51 may have a different amount of heat generation. In this case, the heat dissipation efficiency of the heat dissipation portion 72 of the heat transfer plate 53 joined to the square battery 51 having a large heat generation amount may be higher than the heat dissipation efficiency of the other heat transfer plates 53, You may change the contact area with the weight main body 33 of the heat-transfer plate 53 from the arrangement position of the square battery 51. FIG. In this case, by measuring the internal resistance of each square battery 51 before shipment of the battery module 50, the amount of heat generated before the internal resistance of the square battery 51 is changed by use can be obtained.

  In the embodiment, the thickness of the inter-battery portion (main body portion 71) sandwiched between the square batteries 51 in the heat transfer plate 53 may be within a range where the same connection member 67 can be used or within a range of manufacturing errors. May be different. That is, “the same” in “the lengths of the main body portions 71 (between the batteries) of the plurality of heat transfer plates 53 in the direction in which the prismatic batteries 51 (secondary batteries) are arranged in parallel” is the same as the connection member 67. An error to the extent that the terminals 56 can be connected together and a manufacturing error are allowed.

  In embodiment, if the thickness of the main-body part 71 is the same as the heat-transfer plate 53, the magnitude | size of the main-body part 71 may differ. For example, the shape of the heat radiation part 72 may be the same, and the size of the main body part 71 may be different.

  In the embodiment, a weight other than the weight main body 33 may be used as the heat radiator. For example, when the battery module 50 is accommodated in the casing to form the battery pack 30, the side wall of the casing may be used as a heat radiator.

In the embodiment, a cylindrical battery or the like other than the square battery 51 may be used as the secondary battery.
In the embodiment, a battery module in which the square battery 51 and the heat transfer plate 53 are arranged in parallel may be used without providing the battery holder 52.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(B) The inter-battery portion of the heat transfer plate having a heat dissipation portion with a high heat dissipation efficiency compared with the heat dissipation efficiency of the heat dissipation portion of the other heat transfer plate is the shortest distance between both ends in the parallel arrangement direction of the secondary batteries. 3. The battery module according to claim 2, wherein the battery module is provided between the secondary battery disposed closest to the center of the line connecting the two and the secondary battery adjacent to the secondary battery.

  30 ... Battery pack, 31 ... Counterweight, 50 ... Battery module, 51, 51A, 51B, 51C, 51D ... Square battery, 53, 53A, 53B, 53C, 53D ... Heat transfer plate, 56 ... Terminal, 67 ... Connection 71, body part, 72 ... heat dissipation part.

Claims (4)

A plurality of secondary batteries arranged in parallel;
A plurality of heat transfer plates having a heat dissipating part facing the heat dissipating member and an inter-battery part provided between the plurality of secondary batteries;
A plurality of connecting members for connecting the terminals of the secondary battery, and a battery module comprising:
The inter-battery portions of the plurality of heat transfer plates absorb the heat of the secondary battery, and the lengths in the juxtaposed direction of the plurality of secondary batteries are the same,
The heat dissipating part of the plurality of heat transfer plates dissipates heat from the inter-battery part to the heat dissipating body,
The plurality of heat transfer plates include a heat transfer plate having different heat dissipation efficiency of the heat dissipation portion.   Among the heat transfer plates, the inter-battery portion of the heat transfer plate having a heat dissipation portion with a high heat dissipation efficiency compared to the heat dissipation efficiency of the heat dissipation portion of the other heat transfer plate is the plurality of secondary batteries. The battery module according to claim 1, wherein the battery module is provided between secondary batteries other than the secondary battery located at the endmost in the direction in which the secondary batteries are arranged side by side.   The heat dissipation part having a higher heat dissipation efficiency than the heat dissipation efficiency of the heat dissipation part of the other heat transfer plate has a larger heat capacity than the heat capacity of the heat dissipation part of the other heat transfer plate. Item 3. The battery module according to Item 2.   The heat dissipating part having a high heat dissipating efficiency compared to the heat dissipating efficiency of the heat dissipating part of the other heat transfer plate has a larger contact area with the heat dissipating body than the heat dissipating part of the other heat transfer plate. The battery module according to any one of claims 1 to 3.