Battery pack

Abstract

To provide a battery pack capable of improving recyclability.SOLUTION: A battery pack includes: a plurality of secondary cells 12 each having an external terminal 53; a housing case 13 having a bottom wall 14 and a side wall 15 and configured to store the plurality of secondary cells 12; and a plurality of bus bars 29 removably installed in the housing case 13 and electrically connecting the external terminals 53 of the plurality of secondly cells 12 one another. Each of the bus bars 29 has a rotation shaft 35, and a first extension part 36 and a second extension part 37 extending from a rotation shaft 35 in a direction orthogonal to the rotation shaft 35 and crossing each other. Each of the bus bars 29 rotates about the rotation shaft 35 in a manner that the second extension part 37 comes into contact with the external terminal 53 of the secondary cell 12 when the first extension part 36 is pressed by the secondary cell 12 in response to the insertion of the secondary cell 12 into the housing case 13.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a battery pack for a secondary battery. [Background technology]

[0002] Conventionally, as this type of battery pack, for example, the one shown in Patent Document 1 is known. Such a battery pack is configured to accommodate a plurality of battery modules and a plurality of bus bars in a space formed by a battery case and a cover part. Each battery module has positive and negative terminals. Each bus bar connects the positive terminal of one of two adjacent battery modules to the negative terminal of the other, thereby connecting the battery modules in series. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-91283 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery pack described above, the battery modules and bus bars are fixed to the bottom surface of the battery case via insulating members, which makes it difficult to disassemble the battery pack when it is discarded, and leaves room for improvement in terms of improving the recyclability of the battery pack. [Means for solving the problem]

[0005] Various aspects of the battery pack for solving the above problems will be described below. [Aspect 1] A battery pack comprising: a plurality of secondary batteries having external terminals; a storage case having a bottom wall and side walls and housing the plurality of secondary batteries; and a plurality of bus bars removably assembled within the storage case and electrically connecting the external terminals of the plurality of secondary batteries, wherein each of the bus bars has a rotation axis, and a first extension portion and a second extension portion extending from the rotation axis in a direction perpendicular to the rotation axis and in directions that intersect each other, and wherein when the first extension portion is pressed by the secondary battery as the secondary battery is inserted into the storage case, the second extension portion rotates about the rotation axis as a rotation center so as to contact the external terminal of the secondary battery.

[0006] According to the above configuration, each bus bar is rotatable and detachably assembled in the housing case. That is, each bus bar is not fixed in the housing case by, for example, welding. Therefore, the battery pack can be easily disassembled when discarded, which improves the recyclability of the battery pack.

[0007] [Aspect 2] The battery pack described in [Aspect 1], characterized in that the secondary battery comprises an electrode body formed by winding positive and negative electrode sheets stacked with a separator in between, and a cell case that houses the electrode body, and the external terminal is disposed on the outer surface of a cell side wall that is located in the winding axis direction of the electrode body in the cell case.

[0008] According to the above configuration, the external terminal is arranged on the outer surface of the cell side wall located in the winding axis direction of the electrode body in the cell case of the secondary battery, so that the current path from the electrode body in the secondary battery to the external terminal can be made shorter than when the external terminal is arranged on the outer surface of the top wall of the cell case.

[0009] [Aspect 3] The battery pack described in [Aspect 2], wherein each of the bus bars within the accommodating case has the first extension portion extending along the bottom wall of the accommodating case and the second extension portion extending along the side wall of the accommodating case, an insulating heat conductive member is arranged between the first extension portion and the bottom wall of each of the bus bars within the accommodating case, and a heat dissipation member that dissipates heat transferred from the heat conductive member is provided on an outer surface of the bottom wall of the accommodating case, and each of the bus bars rotates about the pivot axis as a rotation center so that the first extension portion comes into contact with the heat conductive member when the first extension portion is pressed by the secondary battery as the secondary battery is inserted into the accommodating case.

[0010] According to the above configuration, when the secondary battery is inserted into the housing case, the first extension portion of each bus bar contacts the thermally conductive member and the second extension portion contacts the external terminal of the secondary battery. That is, the external terminal and the thermally conductive member contact each other via each bus bar. Therefore, the heat of the secondary battery is transferred from the external terminal to the heat dissipation member via each bus bar and the thermally conductive member, and is then dissipated from the heat dissipation member to the outside of the housing case. Therefore, the heat of the secondary battery can be efficiently dissipated to the outside of the housing case.

[0011] [Aspect 4] A battery pack as described in [Aspect 3], characterized in that the contact surface of the external terminal with which the second extension portion makes face-to-face contact is inclined with respect to the removal direction so that the amount of protrusion in the winding axis direction decreases toward the removal direction of the secondary battery from the storage case.

[0012] According to the above configuration, when the secondary battery is housed in the housing case, the second extension portion is in surface contact with the external terminal and the first extension portion is in surface contact with the thermally conductive member. When the secondary battery is moved in this state from the housing case in the direction of removal, the contact surface of the external terminal presses the second extension portion toward the side wall of the housing case. This causes the bus bar to rotate so that the second extension portion contacts the side wall of the housing case and the first extension portion moves away from the thermally conductive member. This prevents the second extension portion from getting in the way when, for example, another secondary battery is inserted into the position in the housing case after the secondary battery has been removed.

[0013] [Aspect 5] A battery pack as described in [Aspect 3] or [Aspect 4], characterized in that the inner surface of the cell side wall in the cell case is covered by a current collecting terminal connected to the external terminal, and the current collecting terminal and the cell side wall each have a through hole formed therein for venting smoke to the outside of the cell case in the event of smoke being generated within the cell case.

[0014] According to the above configuration, high-temperature smoke generated in the cell case is discharged to the outside of the cell case through the through-hole while exchanging heat with the current collecting terminal connected to the external terminal. This makes it possible to lower the temperature of the smoke discharged from the inside of the cell case to the outside of the cell case through the through-hole. In this case, the heat of the current collecting terminal warmed by heat exchange with the smoke is transferred to the heat dissipation member via the external terminal, each bus bar, and the heat conductive member, and is then discharged from the heat dissipation member to the outside of the housing case. This makes it possible to efficiently dissipate the heat of the smoke generated in the cell case of the secondary battery to the outside of the housing case. Effect of the Invention

[0015] The present invention has an effect of improving recyclability. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing a battery pack according to an embodiment. [Diagram 2] FIG. [Diagram 3] 2 is a perspective view of a storage case with bus bars and bus bar support members disposed therein; FIG. [Figure 4] 4 is a perspective view of the main part of FIG. 3 as viewed from a different angle. [Diagram 5] FIG. 2 is a perspective view of a bus bar and a bus bar support member. [Figure 6] 4 is a cross-sectional view showing a schematic state in which a secondary battery is accommodated in a housing case. FIG. [Figure 7] FIG. 7 is an enlarged view of a main part of FIG. 6. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] 3A to 3C are cross-sectional views illustrating a state in which a secondary battery is accommodated in a storage case and a state in which the secondary battery is removed from the storage case. [Figure 11] 4A and 4B are perspective views showing a state in which a secondary battery is accommodated in the accommodation case and a state in which the secondary battery is removed from the accommodation case. [Figure 12] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment will now be described with reference to the drawings. <Battery Pack 11> As shown in FIG. 1, a battery pack 11 includes a plurality of secondary batteries 12 and a housing case 13 that houses the plurality of secondary batteries 12.

[0018] In the following description, the width direction is designated as X, the depth direction as Y, and the height direction as Z in the attitude of the battery pack 11 in Fig. 1. In the battery pack 11 of this embodiment, the width direction X and the depth direction Y coincide with the horizontal direction, and the height direction Z coincides with the vertical direction. The width direction X, the depth direction Y, and the height direction Z are perpendicular to each other. In the following description, "upper" and "lower" refer to "upper" and "lower" in the attitude of the secondary battery 12 in Fig. 1.

[0019] <Containment Case 13> 1 and 2, the storage case 13 includes a rectangular bottom wall 14 and a pair of rectangular side walls 15 erected on both ends of the bottom wall 14 in the width direction X. One of the pair of side walls 15 is a first side wall 16 and the other is a second side wall 17. The first side wall 16 is thicker than the second side wall 17. The first side wall 16 is slightly taller than the second side wall 17.

[0020] A protrusion 18 is provided at the upper end of the second side wall 17, protruding outward in the width direction X. The protrusion 18 has a rectangular plate shape extending in the depth direction Y. The upper surface of the protrusion 18 is a horizontal plane. The storage case 13 is open at its upper end and on both sides in the depth direction Y. The opening at the upper end of the storage case 13 is closed by a rectangular vibration suppression plate 19.

[0021] The vibration suppression plate 19 presses down each of the secondary batteries 12 housed in the housing case 13 from above, with one end in the width direction X being cantilevered by the upper surface of the first side wall 16. In this way, the vibration suppression plate 19 suppresses movement of each of the secondary batteries 12 in the height direction Z when the secondary batteries 12 are subjected to vibration in the height direction Z.

[0022] A plurality of guide portions 20 are provided in the center of the inner surface of each of the pair of side walls 15 to guide the secondary battery 12 when it is inserted into the housing case 13. Each guide portion 20 has a rectangular plate shape extending in the height direction Z, and is arranged at equal intervals in the depth direction Y. The upper end of each guide portion 20 is located lower than the upper end of the side wall 15, and the lower end is located higher than the lower end of the side wall 15. The plurality of guide portions 20 provided on the inner surfaces of the pair of side walls 15 face each other in the width direction X.

[0023] 2 and 7, a pair of rectangular bottom wall holes 21 are formed penetrating both ends in the width direction X of the bottom wall 14 of the storage case 13 so as to extend in the depth direction Y. A pair of rectangular bottom wall recesses 22 are formed extending in the depth direction Y at both ends in the width direction X of the outer surface of the bottom wall 14. Each bottom wall recess 22 communicates with the bottom wall hole 21 in a region corresponding to the bottom wall hole 21, which is slightly more than half of the outer side in the width direction X.

[0024] A heat dissipation member 23 made of, for example, aluminum is provided in each bottom wall recess 22 on the outer surface of the bottom wall 14. The heat dissipation member 23 includes a rectangular plate-shaped heat conduction portion 24 extending in the depth direction Y, a portion of which fits into the bottom wall recess 22, and a plurality of heat dissipation fins 25 protruding downward from the heat conduction portion 24. The plurality of heat dissipation fins 25 are rectangular plate-shaped extending in the depth direction Y, and are arranged at equal intervals in the width direction X.

[0025] The heat conductive portion 24 has, on its upper surface, a rectangular plate-shaped fitting protrusion 26 that fits into the bottom wall hole 21 and corresponds to the bottom wall hole 21. The fitting protrusion 26 is airtightly adhered to the bottom wall hole 21 with an adhesive. The upper surface of the fitting protrusion 26 when fitted into the bottom wall hole 21 is flush with the inner surface (upper surface) of the bottom wall 14 of the storage case 13.

[0026] 3 and 7, a rectangular plate-like insulating heat conductive member 27 that is slightly larger than the bottom wall hole 21 is disposed on each bottom wall hole 21 on the inner surface of the bottom wall 14 of the storage case 13 so as to cover the entire bottom wall hole 21. The heat conductive member 27 is bonded to the upper surface of the fitting protrusion 26 in the bottom wall hole 21 and to the inner surface of the bottom wall 14. The heat conductive member 27 is made of, for example, aluminum nitride. The heat dissipation member 23 dissipates heat transferred from the heat conductive member 27 to the outside of the storage case 13.

[0027] <Busbar 29> 3 and 4, a pair of busbar support members 28 and a plurality of busbars 29 supported by each busbar support member 28 are disposed at the bottom of the housing case 13. Each busbar support member 28 includes a rectangular plate-shaped base portion 30 extending in the depth direction Y, and a plurality of arm portions 31 extending straight outward in the width direction X from the outer edge of the base portion 30 in the width direction X.

[0028] The multiple arm portions 31 of each busbar support member 28 are arranged at equal intervals in the depth direction Y, and their tips extend to corner portions formed by each side wall 15 and the bottom wall 14. A cylindrical bearing portion 32 whose axis extends in the depth direction Y is provided at the tip of each arm portion 31. The base portions 30 of the pair of busbar support members 28 are arranged side by side in the width direction X between the pair of heat conduction members 27 on the bottom wall 14.

[0029] 3, 4, and 11, a marking portion 33 is provided on the outer end of the top surface of each base portion 30 in the width direction X to indicate the position and orientation of each secondary battery 12 when the secondary battery 12 is inserted into the housing case 13. The marking portion 33 has a "+" symbol indicating the positive electrode side and a "-" symbol indicating the negative electrode side. The marking portion 33 of each base portion 30 is arranged such that the "+" symbols and the "-" symbols are alternately arranged in the depth direction Y.

[0030] In this case, on the base portions 30 of the pair of bus bar support members 28, the "+" symbol of one mark portion 33 and the "-" symbol of the other mark portion 33 are arranged to face each other in the width direction X. A plurality of spacers 34 are protrudingly provided on both ends in the width direction X of the lower surface of each base portion 30 to form a gap between the lower surface of the base portion 30 and the upper surface of the bottom wall 14. The amount of protrusion of the spacers 34 from the lower surface of each base portion 30 is the same as the thickness of the heat conduction member 27. In the gap between the lower surface of the base portion 30 and the upper surface of the bottom wall 14, for example, a flexible printed circuit (FPC) is arranged.

[0031] 4 and 5, a substantially L-shaped plate-like bus bar 29 is disposed between two arm portions 31 adjacent to each other in the depth direction Y of each bus bar support member 28. Each bus bar 29 is formed by bending a substantially U-shaped plate material into a substantially L-shape and fixing a round bar-like rotation shaft 35 extending along an inner corner portion of the bent plate material.

[0032] Each bus bar 29 is rotatably supported by bearings 32 provided at the tips of two arm portions 31 adjacent to each other in the depth direction Y at both ends of a rotation shaft 35. That is, each bus bar 29 is detachably assembled to the bearings 32 of the bus bar support member 28 inside the accommodating case 13 such that the rotation shaft 35 fits along corner portions formed by the side walls 15 and the bottom wall 14 inside the accommodating case 13 and extending in the depth direction Y.

[0033] Each bus bar 29 has a rotation axis 35, and a first extending portion 36 and a pair of second extending portions 37 extending from the rotation axis 35 in a direction perpendicular to the rotation axis 35 and in directions intersecting each other. In each bus bar 29 inside the accommodating case 13, the first extending portion 36 having a substantially rectangular plate shape extends from the rotation axis 35 along the bottom wall 14 of the accommodating case 13 in the width direction X, and the pair of second extending portions 37 having a substantially rectangular plate shape extend in the height direction Z along the side wall 15 of the accommodating case 13.

[0034] The pair of second extending portions 37 are arranged side by side at a predetermined interval in the depth direction Y. Portions of the pair of second extending portions 37 other than the tip portions 37a are general portions 37b extending straight from the rotation shaft 35. The tip portions 37a of the pair of second extending portions 37 are warped outward in the width direction X with respect to the general portions 37b. The pair of second extending portions 37 are arranged to sandwich the guide portion 20 in the depth direction Y. The angle between the first extending portion 36 and the second extending portion 37 of each bus bar 29 is slightly smaller than a right angle.

[0035] The length of the first extension portion 36 from the rotation shaft 35 is slightly shorter than the length of the second extension portion 37 from the rotation shaft 35. The first extension portion 36 of each bus bar 29 is disposed between two arm portions 31 adjacent to each other in the depth direction Y and above the heat conductive member 27. Therefore, the heat conductive member 27 is disposed between the first extension portion 36 of each bus bar 29 and the bottom wall 14 inside the accommodation case 13.

[0036] <Secondary battery 12> As shown in Fig. 1 and Fig. 6, the secondary battery 12 has a generally rectangular plate shape. The secondary battery 12 is accommodated in the accommodation case 13 in a position in which the long side direction coincides with the width direction X, the short side direction coincides with the height direction Z, and the thickness direction coincides with the depth direction Y. The secondary battery 12 includes an electrode body 38 and a cell case 39 that accommodates the electrode body 38. The secondary battery 12 of this embodiment has a configuration as a lithium ion secondary battery in which the electrode body 38 in the cell case 39 is impregnated with a non-aqueous electrolyte solution (not shown). The electrolyte solution is one in which a lithium salt serving as a supporting salt is dissolved in an organic solvent.

[0037] <Electrode body 38> As shown in Fig. 1 and Fig. 6, the electrode body 38 is configured by laminating and integrating a strip-shaped positive electrode sheet 40 as an example of an electrode sheet, a strip-shaped negative electrode sheet 41 as an example of an electrode sheet, and a strip-shaped separator 42. That is, the laminate of the positive electrode sheet 40, the negative electrode sheet 41, and the separator 42 is wound around a winding axis extending in the width direction (width direction X) of these. As a result, the electrode body 38 is formed in which the positive electrode sheet 40 and the negative electrode sheet 41 are alternately arranged in the radial direction with the separator 42 sandwiched between them. The separator 42 is formed, for example, of a porous film made of an insulating synthetic resin.

[0038] The positive electrode sheet 40 has a strip-shaped positive electrode collector 43 and a positive electrode active material layer laminated on the positive electrode collector 43. The positive electrode collector 43 is made of, for example, aluminum foil. The positive electrode active material layer is laminated on the positive electrode collector 43 by applying a composite paste containing a lithium transition metal oxide serving as a positive electrode active material and a binder onto the positive electrode collector 43. In this case, the positive electrode active material layer is laminated on the positive electrode collector 43 with one edge portion in the width direction (width direction X) of the positive electrode collector 43 exposed.

[0039] The negative electrode sheet 41 has a strip-shaped negative electrode collector 44 and a negative electrode active material layer laminated on the negative electrode collector 44. The negative electrode collector 44 is made of, for example, copper foil. The negative electrode active material layer is laminated on the negative electrode collector 44 by applying a composite paste containing a carbon-based material that serves as a negative electrode active material and a binder onto the negative electrode collector 44. In this case, the negative electrode active material layer is laminated on the negative electrode collector 44 in a state where the other end edge portion, which is opposite to one end edge portion side in the width direction (width direction X) of the negative electrode collector 44, is exposed.

[0040] <Cell Case 39> 1, 6 and 8, the cell case 39 is made of, for example, a synthetic resin. The cell case 39 includes a case body 45 in the shape of a flat rectangular box with a bottom, and a rectangular plate-like cover member 47 that closes a rectangular opening 46 that opens to one side of the case body 45 in the depth direction Y. The electrode body 38 is housed in the cell case 39 with the winding axis of the electrode body 38 extending in the width direction X. The electrode body 38 has a flat shape that matches the shape inside the cell case 39.

[0041] 6, 8, and 9, a pair of side walls facing each other in the width direction X, which is the winding axis direction in which the winding axis of the electrode body 38 housed in the case body 45 extends, are cell side walls 48. A first long hole 49, which is an example of a through hole, is formed penetrating through the center of each of the pair of cell side walls 48 in the height direction Z. The first long hole 49 is closed by a plate-like sealing member 50 that is weaker than the cell side wall 48. The sealing member 50 has the same shape as the first long hole 49, and is fixed in a state where it is fitted into the first long hole 49.

[0042] A metallic terminal forming member 51 is provided on each of the pair of cell side walls 48 by, for example, insert molding. The terminal forming member 51 is configured such that a current collecting terminal 52 and an external terminal 53 are integrally formed via a connecting portion 54. The current collecting terminal 52 has a rectangular plate shape extending in the height direction Z, and is disposed so as to cover the entire inner surface of the cell side wall 48. That is, the current collecting terminal 52 is disposed on the inner surface of the cell side wall 48.

[0043] A second long hole 55, which is an example of a through hole that is slightly larger than the first long hole 49, is formed penetrating the current collecting terminal 52 at a position facing the first long hole 49 in the width direction X. The first long hole 49 and the second long hole 55 communicate with each other. The first long hole 49 and the second long hole 55 have the function of discharging smoke to the outside of the cell case 39 when smoke is generated inside the cell case 39.

[0044] 6 and 9, a block-shaped external terminal 53 larger than the connecting portion 54 is integrally formed on the outer surface of the current collecting terminal 52 at a position below the second elongated hole 55 via the block-shaped connecting portion 54. The external terminal 53 is electrically connected to the current collecting terminal 52 via the connecting portion 54. The connecting portion 54 is embedded in the cell side wall 48. The external terminal 53 is exposed from the outer surface of the cell side wall 48. That is, the external terminal 53 is disposed on the outer surface of the cell side wall 48.

[0045] As shown in Figure 6, each of the current collecting terminals 52 covering the inner surfaces of a pair of cell side walls 48 is bonded by a conductive adhesive, one in contact with the positive current collector 43 of the electrode body 38 housed in the case body 45, and the other in contact with the negative current collector 44 of the electrode body 38 housed in the case body 45.

[0046] In this case, of the external terminals 53 arranged on the outer surfaces of a pair of cell side walls 48, the one corresponding to the collector terminal 52 electrically connected to the positive electrode collector 43 of the electrode body 38 serves as the positive electrode terminal of the secondary battery 12, and the one corresponding to the collector terminal 52 electrically connected to the negative electrode collector 44 of the electrode body 38 serves as the negative electrode terminal of the secondary battery 12.

[0047] 1 and 8, a "+" symbol indicating the positive electrode side is marked on the end of the upper surface of the case body 45 of the secondary battery 12 on the positive electrode terminal side in the width direction X. A "-" symbol indicating the negative electrode side is marked on the upper surface of the case body 45 of the secondary battery 12 on the end of the negative electrode terminal side in the width direction X.

[0048] A rectangular plate-shaped protrusion 56 protruding upward is formed in the center in the width direction X on the upper surface of the case body 45 of the secondary battery 12. A two-dimensional code (not shown) is printed on the tip surface of the protrusion 56. This two-dimensional code contains various information about the secondary battery 12.

[0049] Holes 57 are formed through the vibration suppression plate 19 at positions corresponding to the protrusions 56 of the multiple secondary batteries 12 when housed in the housing case 13, into which the protrusions 56 are inserted when the opening at the top end of the housing case 13 is closed by the vibration suppression plate 19. Therefore, even when the opening at the top end of the housing case 13 containing multiple secondary batteries 12 is closed by the vibration suppression plate 19, the two-dimensional code (not shown) printed on the tip surface of the protrusion 56 of each secondary battery 12 is exposed from the hole 57.

[0050] <External terminal 53> 6 and 7 , the external terminals 53 of each secondary battery 12 accommodated in the accommodation case 13 are in surface contact with the second extension portion 37 of the bus bar 29. As a result, each bus bar 29 electrically connects the external terminals 53 of the multiple secondary batteries 12 together.

[0051] The contact surface 53a of the external terminal 53 with which the second extending portion 37 comes into surface contact is inclined upward so that the amount of outward protrusion in the width direction X, which is the winding axis direction of the electrode body 38, decreases the further upward, which is the removal direction of the secondary battery 12 from the housing case 13. In other words, the contact surface 53a of the external terminal 53 is inclined with respect to the vertical plane so as to be positioned further inward in the width direction X the further upward.

[0052] <Operation of the embodiment> 10 and 11 , before the secondary battery 12 is accommodated in the housing case 13, the first extension portion 36 of each bus bar 29 is separated from the thermally conductive member 27 and the second extension portion 37 is in contact with the inner surface of the side wall 15. When the secondary battery 12 is to be accommodated in the housing case 13 from the opening at the top end in this state, first, the "+" and "-" symbols displayed on the top surface of the base portion 30 of each bus bar support member 28 and the "+" and "-" symbols displayed on the top surface of the secondary battery 12 are checked to correctly align the orientation of the secondary battery 12.

[0053] Next, the secondary battery 12 is inserted into the housing case 13 along the guide portion 20. Then, when the secondary battery 12 is inserted all the way into the housing case 13, the first extension portion 36 of the bus bar 29 is pressed downward by the secondary battery 12. Then, as shown in Figs. 6 and 7, the bus bar 29 rotates about the rotation axis 35 so that the first extension portion 36 comes into surface contact with the thermally conductive member 27 and the second extension portion 37 comes into surface contact with the external terminal 53 of the secondary battery 12.

[0054] In the same manner, when the multiple secondary batteries 12 are sequentially inserted deep into the housing case 13, the multiple secondary batteries 12 are housed in the housing case 13 lined up in the depth direction Y. At this time, the multiple secondary batteries 12 are electrically connected in series at their external terminals 53 by the respective bus bars 29. Next, as shown in Fig. 12, with the opening at the top end of the housing case 13 covered by the vibration suppression plate 19, one end of the vibration suppression plate 19 in the width direction X is attached to the top surface of the first side wall 16. In this way, the battery pack 11 is assembled.

[0055] In this case, as shown in Fig. 12, each secondary battery 12 housed in the housing case 13 is pressed downward from the top by the vibration suppression plate 19. Therefore, even if each secondary battery 12 is subjected to vibration in the height direction Z, the vibration suppression plate 19 suppresses movement of each secondary battery 12 in the height direction Z. Furthermore, in this case, the protrusions 56 on the upper surface of the secondary battery 12 are inserted into the holes 57 of the vibration suppression plate 19, so that a two-dimensional code (not shown) printed on the tip surface of the protrusions 56 is exposed from the holes 57. Therefore, the two-dimensional code can be read by a two-dimensional code reader without removing the vibration suppression plate 19 from the housing case 13.

[0056] In addition, when each secondary battery 12 housed in the housing case 13 is pressed downward by the vibration suppression plate 19, the first extension portion 36 of the bus bar 29 is pressed further downward by the secondary battery 12. This increases the contact pressure of the first extension portion 36 against the thermal conductive member 27 and the contact pressure of the second extension portion 37 against the external terminals 53 of the secondary battery 12, ensuring sufficient contact pressure.

[0057] Furthermore, when the battery pack 11 is used, the electrode body 38 of each secondary battery 12 generates heat. However, the heat generated by the electrode body 38 of each secondary battery 12 is transferred to the heat dissipation member 23 via the current collecting terminal 52, the connecting portion 54, the external terminal 53, the bus bar 29, and the heat conductive member 27, and is then dissipated from the heat dissipation member 23 to the outside of the housing case 13. Therefore, each secondary battery 12 is effectively cooled.

[0058] Furthermore, in each secondary battery 12, when the pressure inside the cell case 39 exceeds a predetermined value due to overheating of the electrode body 38, the sealing member 50 is destroyed by the pressure. At this time, high-temperature smoke generated inside the electrode body 38 in the cell case 39 is discharged to the outside of the cell case 39 through the second long hole 55 and the first long hole 49 while being cooled by heat exchange with the current collecting terminal 52. Therefore, the temperature of the smoke discharged from inside the cell case 39 to the outside of the cell case 39 through the second long hole 55 and the first long hole 49 is kept low.

[0059] Furthermore, when removing the secondary battery 12 from the housing case 13, the vibration suppression plate 19 is removed from the housing case 13, and then the secondary battery 12 is grasped and moved straight upward. At this time, as shown in Figures 10 and 11, the contact surface 53a of the external terminal 53 of the secondary battery 12 slides upward against the inner surface in the width direction X of the second extension portion 37 of the bus bar 29, and presses the second extension portion 37 outward in the width direction X.

[0060] Then, the bus bar 29 is rotated so that the second extension portion 37 comes into contact with the side wall 15 of the storage case 13 and the first extension portion 36 moves away from the heat conductive member 27. Therefore, the second extension portion 37 does not get in the way when, for example, inserting another secondary battery 12 into the position in the storage case 13 after the secondary battery 12 has been removed.

[0061] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) The battery pack 11 includes a plurality of secondary batteries 12 having external terminals 53, a storage case 13 having a bottom wall 14 and a side wall 15 and housing the plurality of secondary batteries 12, and a plurality of bus bars 29 removably assembled within the storage case 13 and electrically connecting the external terminals 53 of the plurality of secondary batteries 12. Each bus bar 29 has a rotation axis 35, and a first extension portion 36 and a second extension portion 37 extending from the rotation axis 35 in a direction perpendicular to the rotation axis 35 and in directions intersecting each other. When the first extension portion 36 is pressed by the secondary battery 12 as the secondary battery 12 is inserted into the storage case 13, each bus bar 29 rotates about the rotation axis 35 as a rotation center such that the second extension portion 37 comes into contact with the external terminal 53 of the secondary battery 12.

[0062] According to the above configuration, each bus bar 29 is rotatable and is detachably assembled inside the housing case 13. That is, each bus bar 29 is not fixed inside the housing case 13 by, for example, welding. Therefore, the battery pack 11 can be easily disassembled when it is discarded, and the recyclability of the battery pack 11 can be improved.

[0063] (2) In the battery pack 11, the secondary battery 12 includes an electrode assembly 38 formed by winding positive and negative electrode sheets stacked with a separator 42 in between, and a cell case 39 that houses the electrode assembly 38. The external terminals 53 are disposed on the outer surface of a cell side wall 48 located in the width direction X, which is the winding axis direction of the electrode assembly 38 in the cell case 39.

[0064] According to the above configuration, the external terminal 53 is arranged on the outer surface of the cell side wall 48 located in the width direction X, which is the winding axis direction of the electrode body 38 in the cell case 39 of the secondary battery 12. Therefore, the current path from the electrode body 38 in the secondary battery 12 to the external terminal 53 can be made shorter than when the external terminal 53 is arranged on the outer surface of the upper wall of the cell case 39.

[0065] (3) In the battery pack 11, each bus bar 29 in the housing case 13 has a first extension portion 36 that extends along the bottom wall 14 of the housing case 13, and a second extension portion 37 that extends along the side wall 15 of the housing case 13. An insulating heat conductive member 27 is disposed between the first extension portion 36 of each bus bar 29 and the bottom wall 14 in the housing case 13. A heat dissipation member 23 that dissipates heat transferred from the heat conductive member 27 is provided on the outer surface of the bottom wall 14 of the housing case 13. When the first extension portion 36 is pressed by the secondary battery 12 as the secondary battery 12 is inserted into the housing case 13, each bus bar 29 rotates about a rotation axis 35 such that the first extension portion 36 comes into contact with the heat conductive member 27.

[0066] According to the above configuration, when the secondary battery 12 is inserted into the housing case 13, the first extension portion 36 of each bus bar 29 contacts the heat conductive member 27 and the second extension portion 37 contacts the external terminal 53 of the secondary battery 12. That is, the external terminal 53 and the heat conductive member 27 contact each other via each bus bar 29. Therefore, the heat of the secondary battery 12 is transferred from the external terminal 53 to the heat dissipation member 23 via each bus bar 29 and the heat conductive member 27, and is then dissipated from the heat dissipation member 23 to the outside of the housing case 13. Therefore, the heat of the secondary battery 12 can be efficiently dissipated to the outside of the housing case 13.

[0067] (4) In the battery pack 11, the contact surface 53a with which the second extension portion 37 of the external terminal 53 makes face-to-face contact is inclined with respect to the removal direction (upward) in which the secondary battery 12 is removed from the housing case 13 so that the amount of protrusion in the winding axis direction (width direction X) decreases toward the removal direction (upward).

[0068] According to the above configuration, when the secondary battery 12 is housed in the housing case 13, the second extension portion 37 is in surface contact with the external terminal 53, and the first extension portion 36 is in surface contact with the heat conductive member 27. When the secondary battery 12 is moved in this state from the housing case 13 in the removal direction, the contact surface 53a of the external terminal 53 presses the second extension portion 37 toward the side wall 15 of the housing case 13. As a result, the bus bar 29 is rotated such that the second extension portion 37 contacts the side wall 15 of the housing case 13, and the first extension portion 36 moves away from the heat conductive member 27. This prevents the second extension portion 37 from getting in the way when, for example, another secondary battery 12 is inserted into the position in the housing case 13 after the secondary battery 12 has been removed.

[0069] (5) In the battery pack 11, the inner surface of the cell side wall 48 of the cell case 39 is covered with a current collecting terminal 52 connected to an external terminal 53. The current collecting terminal 52 and the cell side wall 48 are respectively formed with a second long hole 55 and a first long hole 49 for discharging smoke to the outside of the cell case 39 in the event that smoke is generated inside the cell case 39.

[0070] According to the above configuration, high-temperature smoke generated in the cell case 39 is discharged to the outside of the cell case 39 through the second long hole 55 and the first long hole 49 while exchanging heat with the current collecting terminal 52 connected to the external terminal 53. Therefore, the temperature of the smoke discharged from the inside of the cell case 39 to the outside of the cell case 39 through the second long hole 55 and the first long hole 49 can be lowered. In this case, the heat of the current collecting terminal 52 warmed by heat exchange with the smoke is transferred to the heat dissipation member 23 through the external terminal 53, each bus bar 29, and the heat conductive member 27, and then discharged from the heat dissipation member 23 to the outside of the housing case 13. Therefore, the temperature of the smoke discharged from the inside of the cell case 39 to the outside of the cell case 39 through the second long hole 55 and the first long hole 49 can be lowered while the heat of the smoke generated in the cell case 39 of the secondary battery 12 is efficiently discharged to the outside of the housing case 13.

[0071] (6) In the battery pack 11, a “+” symbol and a “-” symbol are displayed on the upper surface of the base portion 30 of each busbar support member 28, and a “+” symbol and a “-” symbol are displayed on the upper surface of the secondary battery 12.

[0072] According to the above configuration, when the secondary battery 12 is placed into the storage case 13 through the opening at the top end, the orientation of the secondary battery 12 can be correctly aligned by looking at the "+" and "-" symbols displayed on the top surface of the base portion 30 of each busbar support member 28 and the "+" and "-" symbols displayed on the top surface of the secondary battery 12. This makes it possible to prevent the secondary battery 12 from being inserted into the storage case 13 in the wrong orientation.

[0073] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.

[0074] The inner surface of the cell side wall 48 of the cell casing 39 does not necessarily have to be covered with the current collecting terminal 52 connected to the external terminal 53 . The current collecting terminal 52 and the cell side wall 48 do not necessarily need to have the second long hole 55 and the first long hole 49, respectively, for discharging smoke to the outside of the cell case 39 if smoke is generated inside the cell case 39.

[0075] The contact surface 53a with which the second extension portion 37 of the external terminal 53 comes into surface contact does not necessarily have to be inclined with respect to the removal direction (upward) in which the secondary battery 12 is removed from the casing 13 so that the amount of protrusion in the winding axis direction (width direction X) decreases toward the removal direction (upward).

[0076] Each bus bar 29 in the accommodating case 13 does not necessarily have to have the first extension portion 36 extending along the bottom wall 14 of the accommodating case 13 and the second extension portion 37 extending along the side wall 15 of the accommodating case 13 .

[0077] It is not necessarily required to dispose the insulating heat conductive member 27 between the first extending portion 36 of each bus bar 29 and the bottom wall 14 inside the accommodating case 13 . The heat dissipation member 23 does not necessarily have to be provided on the outer surface of the bottom wall 14 of the storage case 13 .

[0078] The external terminal 53 does not necessarily have to be disposed on the outer surface of the cell side wall 48 located in the width direction X which is the winding axis direction of the electrode body 38 in the cell casing 39. In other words, the external terminal 53 may be disposed on the upper part of the cell casing 39, for example.

[0079] The position of the second long hole 55 in the current collecting terminal 52 and the position of the first long hole 49 in the cell side wall 48 may be changed as appropriate. In this case, the higher the second long hole 55 in the current collecting terminal 52 and the first long hole 49 in the cell side wall 48 are positioned, the longer the smoke generated in the cell case 39 will be in contact with the current collecting terminal 52, and therefore the greater the effect of cooling the smoke by the current collecting terminal 52. Therefore, it is preferable to position the second long hole 55 in the current collecting terminal 52 and the first long hole 49 in the cell side wall 48 as high as possible.

[0080] The upper surface of the base portion 30 of each bus bar support member 28 does not necessarily need to have a “+” symbol and a “-” symbol displayed thereon. The holes 57 in the vibration suppression plate 19 may be omitted.

[0081] The secondary battery 12 may be a secondary battery having a configuration other than a lithium ion secondary battery. [Explanation of symbols]

[0082] 11…Battery pack 12…Secondary battery 13…Storage case 14…Bottom wall 15…Side wall 16…First side wall 17…Second side wall 18...Protrusion 19...Vibration suppression plate 20…Information department 21…Bottom wall hole 22…Bottom wall recess 23...Heat dissipation member 24…Heat conductive section 25…Heat dissipation fin 26…Fitting protrusion 27...Heat conductive material 28... Busbar support member 29…Busbar 30…Base section 31…Arm section 32...Bearing part 33…Mark section 34…Spacer 35...Pivot shaft 36...First extension part 37…Second extension part 37a...Tip 37b…General section 38...Electrode body 39…Cell case 40...Positive electrode sheet as an example of an electrode sheet 41... Negative electrode sheet as an example of an electrode sheet 42…Separator 43...Positive electrode current collector 44...Negative electrode current collector 45…Case body 46…Opening 47…Cover member 48…Cell side wall 49...First long hole as an example of a through hole 50...Sealing member 51...Terminal forming member 52...Current collector terminal 53...External terminal 53a…Contact surface 54...Connection part 55...Second long hole as an example of a through hole 56…Convex part 57...hole X…Width direction Y: Depth direction Z: Height direction

Claims

1. A plurality of secondary batteries having external terminals; a housing case having a bottom wall and a side wall and housing a plurality of the secondary batteries; a plurality of bus bars that are detachably assembled in the housing case and electrically connect the external terminals of the plurality of secondary batteries; Equipped with Each of the bus bars is A battery pack comprising a pivot axis, and a first extension portion and a second extension portion extending from the pivot axis in a direction perpendicular to the pivot axis and intersecting each other, and wherein when the first extension portion is pressed by the secondary battery as the secondary battery is inserted into the storage case, the battery pack rotates about the pivot axis as a rotation center so that the second extension portion comes into contact with the external terminal of the secondary battery.

2. The secondary battery includes an electrode assembly formed by winding positive and negative electrode sheets stacked with a separator sandwiched therebetween, and a cell case that houses the electrode assembly, 2 . The battery pack according to claim 1 , wherein the external terminal is disposed on an outer surface of a cell side wall located in the winding axis direction of the electrode body in the cell case.

3. each of the bus bars in the housing case has a first extension portion extending along the bottom wall of the housing case and a second extension portion extending along the side wall of the housing case; an insulating heat conductive member is disposed between the first extension portion of each of the bus bars and the bottom wall in the accommodating case; a heat dissipation member that dissipates heat transferred from the heat conduction member is provided on an outer surface of the bottom wall of the storage case, The battery pack according to claim 2, characterized in that each of the bus bars rotates about the pivot axis as a rotation center so that the first extension portion comes into contact with the thermal conductive member when the first extension portion is pressed by the secondary battery as the secondary battery is inserted into the storage case.

4. The battery pack according to claim 3, characterized in that a contact surface with which the second extension portion of the external terminal makes surface contact is inclined with respect to the removal direction so that the amount of protrusion in the winding axis direction decreases toward the removal direction of the secondary battery from the accommodating case.

5. an inner surface of the cell side wall of the cell casing is covered with a current collecting terminal connected to the external terminal, The battery pack according to claim 3 or 4, characterized in that the collector terminal and the cell side wall each have a through hole formed therein for discharging smoke to the outside of the cell case in the event that smoke is generated within the cell case.

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