Battery pack

Abstract

Disclosed herein is a battery pack for accommodating battery modules. More specifically, the battery pack of the present invention comprises a pack case including a module area in which battery modules are disposed, in which the pack case comprises: a bottom plate; the side wall is combined along the periphery of the bottom plate; and a support wall coupled to an inner surface of the side wall, in which the support wall includes a coupling portion protruding in a rib shape on a side opposite to the side wall, and the side wall includes, on an inner side, a recessed insertion groove for inserting the coupling portion of the support wall.

Description

Technical Field

[0001] The present invention relates to a battery pack. More specifically, the present invention relates to a battery pack accommodating a battery module having reinforcing plates on both sides to support each side, wherein the battery pack of the present invention is characterized in that space efficiency is improved by separately generating a weld space generated during welding for fixing the battery module.

[0002] The present application claims priority based on Korean Patent Application No. 10-2022-0124949 filed on September 30, 2022, and the entire contents of the Korean Patent Application are incorporated herein by reference. Background Art

[0003] Types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. These unit secondary battery cells (i.e., unit battery cells) have an operating voltage of about 2.5 to 4.2V. Therefore, if a higher output voltage is required, a plurality of battery cells can be connected in series to form a battery pack. In addition, according to the charge and discharge capacity required for the battery pack, a plurality of battery cells can be connected in parallel to form a battery pack. Therefore, the number of battery cells included in the battery pack can vary according to the required output voltage or charge / discharge capacity.

[0004] For example, when a battery pack is configured by connecting a plurality of battery cells in series / parallel, a battery module composed of a plurality of battery cells is first configured.

[0005] Generally, a battery module includes a plurality of battery cells, and the battery module may be protected by a module frame surrounding the battery cells or by a reinforcing plate supporting both sides, etc., as necessary.

[0006] Figure 1 A type of battery module 10 is shown with both sides supported by reinforcing plates 30. Figure 1 The battery module 10 includes a battery cell stack 20 formed by stacking a plurality of battery cells in one direction, and end plates 40 are respectively coupled to the front and rear of the battery cell stack 20. There is also a reinforcing plate 30 coupled to both sides to protect the battery cell stack 20. At this time, the reinforcing plate 30 may form a step in the up-down direction to facilitate coupling with an adjacent battery module 10.

[0007] Figure 2 Shows that it can accommodate Figure 1 The battery pack housing 50 of the battery pack of the battery module 10 shown, Figure 3 Shown is housed in Figure 2 The battery pack housing 50 Figure 1 A battery module 10 is provided.

[0008] Reference Figure 2 The battery pack housing 50 includes a bottom plate 60 supporting the lower portion of the battery module 10 and a side wall 70 coupled along the periphery of the bottom plate 60. A portion of the side wall 70 may be provided with a support wall 90 to which the reinforcing plate 30 of the battery module 10 may be placed or coupled. It also includes a main partition wall 80 that spans the center thereof and is coupled to the bottom plate 60. The battery module 10 may be placed and accommodated in a space divided by the side wall 70 and the main partition wall 80, as shown in FIG. Figure 3 shown.

[0009] Figure 4 (a) is Figure 2 A cross-sectional view of the support wall 90 and the side wall 70 in the battery pack housing 50, Figure 4 (b) shows Figure 4 (a) shows a state where the reinforcing plate 30 and the supporting wall 90 are combined by placing the battery module 10 .

[0010] The support wall 90 has a height corresponding to the height of the step portion of the battery module 10 so as to be coupled to the reinforcing plate 30 of the battery module 10 formed with the step. The support wall 90 is coupled by welding to be fixed to the inner side wall 70 of the battery pack housing 50, wherein the support wall 90 includes a joint portion 100 protruding forward from the top to set a welding position. As shown in the figure, welding can be performed on the joint portion 100, and the welding can produce a weld Bw across the upper portion of the joint portion 100 and the side wall 70.

[0011] The support wall 90 is as follows Figure 4 As shown in (a), the battery module 10 is welded to the side wall 70. Figure 4 (b) is positioned so that a portion of the reinforcing plate 30 is bonded to the supporting wall 90 fixed to the side wall 70 and is placed on the bottom plate 60 .

[0012] However, as described above, the conventional battery pack has a disadvantage in that the space occupied by the joint 100 for welding the support wall 90 to the side wall 70 cannot be utilized. Summary of the invention

[0013] Technical issues

[0014] Therefore, the present invention is to solve the above-mentioned problems and to provide a battery pack with improved internal space utilization.

[0015] Other purposes and advantages of the present invention will be understood from the following description and become apparent from the embodiments of the present invention. It is also apparent that the purposes and advantages of the present invention can be achieved by the means disclosed in the claims of this patent and their combinations.

[0016] Technical Solution

[0017] According to the present invention, a battery pack for accommodating a battery module is provided, the battery pack comprising: a battery pack housing including a module area in which the battery module is mounted, wherein the battery pack housing comprises: a bottom plate; a side wall coupled along the periphery of the bottom plate; and a support wall coupled to the inner surface of the side wall, wherein: the support wall comprises a coupling portion protruding in a rib shape on a side opposite to the side wall, and the side wall comprises a recessed insertion groove on the inner side for inserting the coupling portion of the support wall.

[0018] The support wall is coupled to the side wall by inserting the coupling part into the insertion groove, and the coupling part and the insertion groove may be fixed to each other by welding.

[0019] The side wall may include: a front frame; a rear frame including terminals for a battery pack; arranged opposite to the front frame, and a pair of side frames, respectively coupled to the ends of the front frame and the rear frame on both sides of the bottom plate, wherein the support wall may be coupled to at least one of the front frame and the rear frame.

[0020] The insertion groove is formed to extend in the length direction of the front frame or the rear frame, and a coupling portion of the support wall coupled with the insertion groove may be formed to extend in the length direction of the support wall corresponding to the insertion groove.

[0021] The battery module includes a battery cell stack and a pair of reinforcing plates, the battery cell stack having a plurality of stacked battery cells, the pair of reinforcing plates being combined to support the two outermost side surfaces of the battery cell stack, wherein the battery module accommodated in a battery pack housing and abutting against a front frame or a rear frame can be fixed to the battery pack housing by at least one reinforcing plate coupled to a supporting wall.

[0022] The battery module may be fixed to the battery pack case by bolts penetrating the combined support wall and reinforcement plate and being threadedly engaged to the bottom plate.

[0023] The reinforcing plate included in the battery module includes a protrusion located at an upper portion, which protrudes to form a step in a height direction of the battery module, wherein the height of the supporting wall may be smaller than the lower end height of the protrusion included in the reinforcing plate coupled to the supporting wall.

[0024] The reinforcing plate included in the battery module includes a protrusion protruding to form a step in a height direction of the battery module, wherein the battery module can be coupled to the support wall by being arranged so that a lower portion of the protrusion of the reinforcing plate is located at an upper end of the support wall.

[0025] The insertion groove includes an inclined surface inclined inwardly at an upper portion, a coupling portion of the support wall is fitted into a space of the insertion groove excluding the inclined surface, and a weld generated by welding may be filled between the coupling portion and the inclined surface.

[0026] The height of the support wall is smaller than that of the side wall, and the coupling portion may be formed at an upper corner of the support wall.

[0027] The side wall includes an inwardly inclined inclined surface at a lower corner combined with the bottom plate and an auxiliary groove formed by the inclined surface, wherein the lower end of the support wall, the lower end of the side wall and the bottom plate can be fixed to each other by welding in the auxiliary groove.

[0028] The auxiliary groove can be filled with a weld seam produced by welding.

[0029] The insertion groove includes inwardly inclined inclined surfaces at the upper and lower parts respectively, the coupling part of the support wall is fitted into the region of the insertion groove except the inclined surfaces, and a weld produced by welding may be filled between the coupling part and the inclined surfaces.

[0030] Beneficial Effects

[0031] According to the present invention, the energy efficiency of the battery can be improved by improving the utilization rate of the internal space of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A conventional battery module is shown.

[0033] Figure 2 A battery pack case included in a conventional battery pack is shown.

[0034] Figure 3 Shown accommodated in Figure 2 A battery module in a battery pack housing.

[0035] Figure 4 yes Figure 2 and Figure 3 A cross-sectional view of a portion of a side wall included in a battery pack housing.

[0036] Figure 5 is a perspective view of a battery pack case in a battery pack according to a first embodiment of the present invention.

[0037] Figure 6 is a cross-sectional view of a bottom plate and a side wall including an insertion groove at an end of the bottom plate.

[0038] Figure 7 A portion of a cross-sectional view of the support wall and side walls is shown.

[0039] Figure 8 A battery module according to the present invention is shown.

[0040] Fig. 9 The battery modules are shown positioned adjacent to the side walls in combination with the support walls.

[0041] Fig.10 It is a combined cross section of the side wall, the supporting wall and the reinforcing plate to illustrate the combination of the supporting wall and the reinforcing plate.

[0042] Fig.11 A process of bonding a support wall and a reinforcing plate to a side wall included in a battery pack according to a second embodiment of the present invention is shown.

[0043] Fig.12 A process of bonding a support wall and a reinforcing plate to a side wall included in a battery pack according to a third embodiment of the present invention is shown. DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be interpreted with their ordinary or dictionary meanings, but should be interpreted with meanings and concepts consistent with the technical concept of the present invention based on the principle that the inventor can appropriately define the concept of the term to best describe his invention.

[0045] Therefore, it should be understood that the embodiments described herein and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, but do not represent the entire technical concept of the present invention, and that various equivalents and modifications that can replace them when the application is filed may exist.

[0046] Furthermore, in describing the present invention, when it is determined that the detailed description of related known configurations or features may obscure the essence of the present invention, the detailed description will be omitted.

[0047] The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, and for the sake of clarity, the shapes and sizes of the components in the drawings may be exaggerated, omitted or schematically shown. Therefore, the size or ratio of each component does not necessarily represent its actual size or ratio.

[0048] The present invention relates to a battery pack for accommodating a battery module M. More specifically, the present invention relates to a battery pack for accommodating a battery module M to which reinforcing plates Pr for supporting side portions are applied on both sides, respectively, wherein the battery pack of the present invention is characterized in that space efficiency is improved by separately generating a space for a weld Bw generated during welding for fixing the battery module M.

[0049] Figures 5 to 10 A battery pack according to a first embodiment of the present invention is shown. Fig.11 A battery pack according to a second embodiment of the present invention is shown. Fig.12 A battery pack according to a third embodiment of the present invention is shown.

[0050] Hereinafter, embodiments of a battery pack according to the present invention will be described with reference to the accompanying drawings.

[0051] (First embodiment)

[0052] Figure 5 is a perspective view of a battery pack case 1000 included in the battery pack according to the first embodiment of the present invention.

[0053] The battery pack housing 1000 of the present invention includes a bottom plate 100, a side wall 200 and a support wall 300. Figure 5 shown.

[0054] The bottom plate 100 serves to support the lower portion of the battery module M accommodated in the battery pack case 1000 .

[0055] The side wall 200 serves to support the side of the battery module M accommodated in the battery pack case 1000 and protect the battery module M from the external environment.

[0056] The side wall 200 is coupled along the periphery of the bottom plate 100 .

[0057] When the side wall 200 is coupled to the bottom plate 100 , a module area Am may be formed on the bottom plate 100 , and a plurality of battery modules M may be disposed in the module area Am.

[0058] The outer surface of the side wall 200 may be provided with a terminal 400 electrically connected to the battery module M accommodated in the pack case 1000 , and the battery pack may be electrically connected to an external device via the terminal 400 .

[0059] More specifically, the side wall 200 includes: a front frame 210 including the terminals 400 of the battery pack; a rear frame 220 disposed opposite to the front frame 210; and a pair of side frames 230 respectively coupled to ends of the front frame 210 and the rear frame 220 at both sides of the bottom plate 100.

[0060] The battery pack case 1000 of the present invention may further include a main partition wall coupled to the bottom plate 100 through the center.

[0061] The main partition wall may be used to protect wirings, bus bars, etc. by inserting them therein, or may be used to divide the space inside the battery pack case 1000 into module areas Am.

[0062] The support wall 300 is coupled to the inner surface of the side wall 200 .

[0063] The support wall 300 is combined and fixed to the side wall 200 and the bottom plate 100 , and serves to support and fix the battery module M of the present invention.

[0064] The side wall 200 and the support wall 300 and the like included in the battery pack case 1000 may be made of aluminum and the like, and the support wall 300 is coupled to the side wall 200 by welding and the like.

[0065] The support wall 300 of the present invention includes a coupling portion 310 protruding in a rib shape at a side opposite to the side wall 200 .

[0066] The coupling part 310 is formed to extend in the length direction of the support wall 300, and preferably protrudes from the upper end of the support wall 300. More specifically, the coupling part 310 is formed at an upper corner of the support wall 300 and protrudes forward therefrom.

[0067] like Figure 5 As shown, the side wall 200 includes an insertion groove 200h1 recessed inwardly so that the coupling portion 310 of the support wall 300 can be inserted.

[0068] That is, the support wall 300 is coupled to the side wall 200 by inserting the protruding coupling portion 310 into the insertion groove 200 h 1 of the side wall 200 .

[0069] Specifically, Figure 5 As shown, the insertion groove 200h1 is formed in at least one of the front frame 210 and the rear frame 220 and extends along a length direction of the front frame 210 or the rear frame 220 .

[0070] The coupling portion 310 of the support wall 300 coupled with the insertion groove 200h1 is formed to extend along the length direction of the support wall 300 corresponding to the insertion groove 200h1.

[0071] Preferably, the support wall 300 of the present invention can be combined and fixed to the side wall 200 by welding the combining portion 310 and the insertion groove 200h1 to each other.

[0072] Figure 6 2 is a cross-sectional view of the bottom plate 100 and the side wall 200 including the insertion groove 200h1 at the end of the bottom plate 100.

[0073] like Figure 6 As shown, the insertion groove 200h1 includes an inclined surface inclined inwardly at an upper portion. Therefore, when the insertion groove 200h1 is viewed in cross section, it becomes a trapezoidal shape including an inclined surface on one side.

[0074] Figure 7 It is a part of the cross section of the support wall 300 and the side wall 200 combined with each other.

[0075] Reference Figure 7, an insertion groove 200h1 is formed on the inner surface of the side wall 200 combined with the end of the bottom plate 100, the support wall 300 is arranged so that the coupling part 310 faces the insertion groove 200h1, and the support wall 300 is combined with the side wall 200 so that the coupling part 310 is inserted into the insertion groove 200h1. At this time, the coupling part 310 is assembled into the space of the insertion groove 200h1 except the inclined surface, and between the coupling part 310 and the inclined surface, an empty space with a triangular cross section, that is, a welding groove 200h2 is formed. Then, the coupling part 310 of the support wall 300 and the insertion groove 200h1 of the side wall 200 are welded through the empty space, and a weld bead Bw generated by welding can be filled into the welding groove 200h2.

[0076] Therefore, due to the welding groove 200h2, the support wall 300 can be closely coupled to the side wall 200 while still being firmly fixed by welding.

[0077] Figure 8 A battery module M according to the present invention is shown.

[0078] like Figure 8 As shown, the battery module M includes: a battery cell stack L having a plurality of battery cells C stacked in a unidirectional manner; and a pair of reinforcing plates Pr combined to support both sides of the battery cell stack L located at the outermost sides.

[0079] The reinforcing plate Pr includes a protruding portion Pr1 that protrudes to form a step in the height direction of the battery module M. Specifically, the reinforcing plate Pr located on one side of the battery module M includes the reinforcing portion Pr1 located at the upper portion, and the reinforcing plate Pr located on the other side includes the protruding portion Pr1 located at the lower portion. Therefore, a pair of adjacent battery modules M can be coupled to each other by the reinforcing plates Pr of an interlocking shape.

[0080] Fig. 9 The battery module M is shown positioned adjacent to the side wall 200 in combination with the support wall 300 .

[0081] like Fig. 9 As shown, the battery module M is mounted on the bottom plate 100 in close contact with the support wall 300 through a side of the protrusion Pr1 located at an upper portion of the reinforcing plate Pr included on both sides facing the support wall 300 .

[0082] like Fig. 9As shown, the height of the support wall 300 is lower than the height of the side wall 200. More specifically, the support wall 300 is preferably lower than the height of the lower end of the protrusion Pr1 of the reinforcing plate Pr to support and combine the lower portion of the protrusion Pr1 located at the upper portion of the reinforcing plate Pr. Therefore, the battery module M is arranged so that the lower portion of the protrusion Pr1 of the reinforcing plate Pr abuts against the upper end of the support wall 300 and is combined to the support wall 300.

[0083] Fig.10 2 is a combined cross section of the side wall 200 , the support wall 300 , and the reinforcing plate Pr to illustrate the combination of the support wall 300 and the reinforcing plate Pr.

[0084] Reference Fig.10 , the reinforcing plate Pr is coupled to the supporting wall 300 and the side wall 200 such that the protrusion Pr1 contacts the inner portion of the side wall 200 and the protrusion Pr1 is supported on the upper portion of the supporting wall 300 .

[0085] The battery module M coupled to the support wall 300 may be fixed to the battery pack case 1000 by bolts Bt. Fig. 9 As shown, the battery module M can be fixed to the battery pack case 1000 by the bolts Bt that penetrate the support wall 300 and the reinforcement plate Pr and are screwed into the bottom plate 100. In this case, since the weld Bw is filled in the welding groove 200h2 of the side wall 200, the reinforcement plate Pr can be tightly combined with the side wall 200 and the support wall 300, thereby having the effect of not wasting the space inside the battery pack case 1000.

[0086] The battery pack of the present invention may further include an upper cover coupled to the pack case 1000 to cover an upper portion of each battery module M accommodated in the pack case 1000. However, since the upper cover is known in the art and does not constitute a main feature of the present invention, a detailed description thereof is omitted.

[0087] (Second embodiment)

[0088] The support wall 300 of the present invention is not only coupled to the side wall 200 by welding the coupling portion 310 and the insertion groove 200 h 1 , but may also be welded to the bottom plate 100 .

[0089] Fig.11 A process of combining the support wall 300 and the reinforcement plate Pr to the side wall 200 included in the battery pack according to the second embodiment of the present invention is shown.

[0090] The side wall 200 according to the second embodiment is characterized in that it includes an inwardly inclined inclined surface at a lower corner thereof combined with the bottom plate 100 and an auxiliary groove 200h3 formed by the inclined surface.

[0091] The auxiliary groove 200h3 has a triangular cross section, and welding can be performed into the auxiliary groove 200h3 space. That is, the lower end of the support wall 300, the lower end of the side wall 200, and the bottom plate 100 can be fixed to each other by welding in the auxiliary groove 200h3.

[0092] The weld Bw generated by welding is filled only in the auxiliary groove 200h3 space so as not to interfere with the close adhesion of the support wall 300 and the side wall 200.

[0093] (Third Embodiment)

[0094] In the present invention, welding at the coupling portion 310 and the insertion groove 200h1 can be performed over a larger area.

[0095] Fig.12 A process of combining the support wall 300 and the reinforcing plate Pr to the side wall 200 included in the battery pack according to the third embodiment of the present invention is shown.

[0096] The side wall 200 according to the third embodiment is characterized in that it includes inclined surfaces inclined inwardly at upper and lower portions of the insertion groove 200h1, respectively.

[0097] like Fig.12 As shown, the coupling part 310 of the support wall 300 is fitted in the region of the insertion groove 200h1 except the inclined surface. By fitting the coupling part 310 into the insertion groove 200h1, the auxiliary groove 200h3 is formed by the inclined surfaces at the upper and lower parts of the coupling part 310.

[0098] The auxiliary groove 200h3 has a triangular cross section, and welding can be performed into the space of each auxiliary groove 200h3. That is, the support wall 300 can be welded to the side wall 200 through a wider space, and the support wall 300 can be fixed to the side wall 200 more stably.

[0099] The welds Bw generated by welding are filled only in the spaces of the auxiliary grooves 200 h 3 located at the upper and lower portions of the coupling portion 310 so as not to interfere with the close adhesion of the support wall 300 to the side wall 200 .

[0100] The present invention has been described in more detail above with reference to the accompanying drawings and embodiments. However, it should be understood that the configuration shown in the accompanying drawings or the embodiments described herein are only one embodiment of the present invention and do not represent the entire technical concept of the present invention, and various equivalents and modifications that can replace them when submitting this application may exist.

[0101] [reference numerals]

[0102] 10: (Conventional technology) Battery module

[0103] 20: (Conventional technology) Battery cell stack

[0104] 30: (Conventional technology) reinforcement plate

[0105] 40: (Conventional technology) end plate

[0106] 50: (Conventional technology) battery pack housing

[0107] 60: (Conventional technology) bottom plate

[0108] 70: (Conventional technology) side wall

[0109] 80: (Conventional technology) Main partition wall

[0110] 90: (Conventional technology) Support wall

[0111] 100: (Conventional technology) joint

[0112] 1000: Battery pack housing

[0113] 100: Base plate

[0114] 200: Sidewall

[0115] 200h1: Insertion slot

[0116] 200h2: Welding tank

[0117] 200h3: Auxiliary slot

[0118] 210: Front frame

[0119] 220: Rear frame

[0120] 230: Side frame

[0121] 300: Support wall

[0122] 310: Joint

[0123] 400: Terminal

[0124] Am: Module area

[0125] BT: Bolt

[0126] Bw: Weld

[0127] C: Battery cell

[0128] L: Battery cell stack

[0129] M: Battery module

[0130] Pr: Reinforcement plate

[0131] Pr1: protrusion

Claims

1. A battery pack accommodating a battery module, comprising: A battery pack housing includes a module area in which the battery module is mounted. Wherein, the battery pack housing comprises: Base plate; a side wall coupled along a perimeter of the base plate; and a support wall coupled to an inner surface of the side wall, wherein: The support wall includes a rib-shaped joint portion protruding on a side opposite to the side wall, and The side wall includes a concave insertion groove on the inner side for inserting the coupling portion of the support wall.

2. The battery pack according to claim 1, wherein: The support wall is coupled to the side wall by inserting the coupling portion into the insertion groove, and The coupling portion and the insertion groove are fixed to each other by welding.

3. The battery pack according to claim 1, wherein: The side wall comprises: a front frame including terminals for said battery pack; a rear frame, arranged opposite to the front frame, and A pair of side frames are respectively coupled to the ends of the front frame and the rear frame on both sides of the bottom plate, wherein The support wall is coupled to at least one of the front frame and the rear frame.

4. The battery pack according to claim 3, wherein: The insertion groove is formed to extend along the length direction of the front frame or the rear frame, and The coupling portion of the support wall coupled with the insertion groove is formed to extend along a length direction of the support wall corresponding to the insertion groove.

5. The battery pack according to claim 3, wherein: The battery module includes a battery cell stack having a plurality of stacked battery cells and a pair of reinforcing plates coupled to support two outermost side surfaces of the battery cell stack. The battery module accommodated in the battery pack case abutting against the front frame or the rear frame is fixed to the battery pack case by at least one of the reinforcing plates coupled to the support wall.

6. The battery pack according to claim 5, wherein: The battery module is fixed to the battery pack case by bolts penetrating the combined support wall and the reinforcement plate and being threadedly engaged to the bottom plate.

7. The battery pack according to claim 5, wherein: The reinforcing plate included in the battery module includes a protruding portion located at an upper portion, the protruding portion protruding to form a step along a height direction of the battery module, wherein The support wall has a height smaller than a lower end height of the protrusion included in the reinforcement plate coupled to the support wall.

8. The battery pack according to claim 5, wherein: The reinforcing plate included in the battery module includes a protrusion, the protrusion protruding to form a step along the height direction of the battery module, wherein The battery module is coupled to the support wall by being arranged such that a lower portion of the protrusion of the reinforcing plate is located at an upper end of the support wall.

9. The battery pack according to claim 1, wherein: The insertion groove includes an inclined surface at an upper portion that is inclined inwardly, The coupling portion of the support wall is fitted into a space of the insertion groove excluding the inclined surface, and A weld created by welding is filled between the joining portion and the inclined surface.

10. The battery pack according to claim 1, wherein: The height of the support wall is smaller than the height of the side wall, and The coupling portion is formed at an upper corner of the supporting wall.

11. The battery pack according to claim 1, wherein: The side wall includes an inwardly inclined inclined surface at a lower corner portion combined with the bottom plate and an auxiliary groove formed by the inclined surface, wherein The lower end of the support wall, the lower end of the side wall, and the bottom plate are fixed to each other by welding in the auxiliary groove.

12. The battery pack according to claim 11, wherein: The auxiliary groove is filled with a weld seam produced by welding.

13. The battery pack according to claim 1, wherein: The insertion groove includes inwardly inclined inclined surfaces located at the upper and lower parts, respectively, The coupling portion of the support wall is fitted into a region of the insertion groove excluding the inclined surface, and A weld created by welding is filled between the joining portion and the inclined surface.

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