Battery pack

Abstract

The present invention relates to a battery pack accommodating battery modules. More specifically, the battery pack of the present invention includes a pack case including a plurality of module regions in which battery modules are seated, the pack case including a base plate, a side wall coupled along an edge of the base plate, and a support wall coupled to an inner surface of the side wall, the support wall including a coupling portion protruding in a rib shape on one side facing the side wall, and the side wall including an insertion groove recessed on an inner side into which the coupling portion of the support wall can be inserted.

Description

[Technical Field]

[0001] The present invention relates to a battery pack, more particularly, to a battery pack accommodating battery modules each having a reinforcing plate for supporting a side surface thereof, and the battery pack of the present invention is characterized by improving space efficiency by separately creating a weld bead space that is generated during a welding process for fixing the battery modules.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0124949, filed on September 30, 2022, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] Types of secondary batteries include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is approximately 2.5V to 4.2V. Therefore, if a higher output voltage is required, a battery pack may be configured by connecting a plurality of battery cells in series. Alternatively, a battery pack may be configured by connecting a number of battery cells in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of battery cells included in the battery pack may be variously set depending on the required output voltage or charge / discharge capacity.

[0004] For example, when a battery pack is constructed by connecting a plurality of battery cells in series / parallel, a battery module made up of the plurality of battery cells is first constructed.

[0005] Generally, a battery module includes a plurality of cells, and the battery module may be protected by a module frame that surrounds the cells, or may be protected via a reinforcing plate that supports both sides, as needed.

[0006] FIG. 1 shows a type of battery module 10 supported on both sides by reinforcing plates 30. As shown in FIG. 1, the battery module 10 includes a cell stack 20 in which a plurality of cells are stacked in one direction, and end plates 40 are coupled to the front and rear of the cell stack 20. Reinforcing plates 30 are coupled to both sides of the cell stack 20 to protect the cell stack 20. In this case, the reinforcing plates 30 may have steps formed in the vertical direction to facilitate engagement with adjacent battery modules 10.

[0007] FIG. 2 shows a pack case 50 of a battery pack in which the battery module 10 shown in FIG. 1 can be accommodated, and FIG. 3 shows the state in which the battery module 10 of FIG. 1 is accommodated in the pack case 50 of FIG. 2.

[0008] 2, the pack case 50 includes a base plate 60 that supports the lower portion of the battery module 10, and a side wall 70 that is coupled along the edge of the base plate 60. A support wall 90 may be provided at a portion of the side wall 70, to which the reinforcing plate 30 of the battery module 10 to be mounted or coupled. The pack case 50 also includes a main partition wall 80 that is coupled to the base plate 60 across the center. The battery module 10 may be mounted and housed in a space defined by the side wall 70 and the main partition wall 80, as shown in FIG.

[0009] FIG. 4 shows a cross section of the support wall 90 and the side wall 70 of the pack case 50 of FIG.

[0010] The support wall 90 has a height corresponding to the height of the stepped portion of the battery module 10 so that it can be coupled to the reinforcing plate 30 of the battery module 10, which has a step. The support wall 90 is coupled by welding so that it can be fixed to the inside of the side wall 70 of the pack case 50, and the support wall 90 includes a coupling portion 100 that protrudes forward from an upper end to provide a welding site. The welding can be performed on the coupling portion 100 as shown, and a weld bead Bw can be generated over the upper portion of the coupling portion 100 and across the side wall 70.

[0011] Therefore, the support wall 90 is connected to the side wall 70 by welding as shown in FIG. 4(a), and the battery module 10 is mounted on the base plate 60 such that a portion of the reinforcing plate 30 is engaged with and connected to the support wall 90 fixed to the side wall 70 as shown in FIG. 4(b).

[0012] However, the conventional battery pack has a drawback in that the space occupied by the joint 100 for welding the support wall 90 to the side wall 70 cannot be fully utilized. Summary of the Invention [Problem to be solved by the invention]

[0013] Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a battery pack with improved internal space utilization.

[0014] Other objects and advantages of the present invention can be understood from the following description and become more apparent from the embodiments of the present invention. Also, it is easily understood that the objects and advantages of the present invention can be realized by the means and combinations thereof as claimed. [Means for solving the problem]

[0015] According to the present invention, there is provided a battery pack for accommodating battery modules, the battery pack including a pack case including a plurality of module regions in which the battery modules are seated, the pack case including a base plate, side walls coupled along edges of the base plate, and support walls coupled to inner surfaces of the side walls, the support walls including coupling portions that protrude in a rib shape on one side facing the side walls, and the side walls including recessed insertion grooves on their interior sides into which the coupling portions of the support walls can be inserted.

[0016] The support wall may be coupled to the side wall by inserting the coupling portion into the insertion groove, and the coupling portion and the insertion groove may be fixed to each other by welding.

[0017] The side wall includes a front frame including terminals of a battery pack, a rear frame disposed opposite the front frame, and a pair of side frames coupled to ends of the front frame and rear frame, respectively, on both sides of a base plate, and the support wall can be coupled to at least one of the front frame and the rear frame.

[0018] The insertion groove may be formed to extend along the longitudinal direction of the front frame or the rear frame, and the connecting portion of the support wall connected to the insertion groove may be formed to extend along the longitudinal direction of the support wall corresponding to the insertion groove.

[0019] The battery module includes a cell stack in which a plurality of cells are stacked, and a pair of reinforcing plates coupled to support both outermost side surfaces of the cell stack, and the battery module accommodated in the pack case so as to abut against the front frame or the rear frame can be fixed to the pack case by coupling one of the reinforcing plates to the support wall.

[0020] The battery module coupled to the support wall may be fixed to the pack case by a bolt that passes through the coupled support wall and reinforcing plate and is screwed into the base plate.

[0021] The reinforcing plate included in the battery module may include a protruding portion at an upper portion thereof that protrudes to form a step along the height direction of the battery module, and the height of the support wall may be lower than the height of a lower end of the protrusion included in the reinforcing plate that is coupled to the support wall.

[0022] The reinforcing plate included in the battery module may include a protruding portion that protrudes to form a step along a height direction of the battery module, and the battery module may be coupled to the support wall such that a lower portion of the protruding portion of the reinforcing plate is placed on an upper end of the support wall.

[0023] The insertion groove includes an inclined surface at its upper portion that slopes inward, and the joint portion of the support wall is fitted into the area of ​​the insertion groove excluding the inclined surface, and a weld bead produced by welding can be filled between the joint portion and the inclined surface.

[0024] The support wall may have a height less than that of the side wall, and the joint may be formed at an upper edge of the support wall.

[0025] The side wall includes an inclined surface inclined inward at the edge of the lower end that is connected to the base plate, and an auxiliary groove formed by the inclined surface, and the lower end of the support wall, the lower end of the side wall, and the base plate can be fixed to each other by welding within the auxiliary groove.

[0026] The auxiliary groove can be filled with a weld bead produced by welding.

[0027] The insertion groove includes inwardly inclined inclined surfaces at the top and bottom, respectively, and the joint portion of the support wall is fitted into the area of ​​the insertion groove excluding the inclined surfaces, and a weld bead produced by welding can be filled between the joint portion and the inclined surfaces. [Effects of the Invention]

[0028] According to the present invention, it is possible to improve the space utilization rate inside the battery pack and improve the energy efficiency of the battery. [Brief explanation of the drawings]

[0029] [Figure 1] 1 shows a conventional battery module. [Figure 2] 1 shows a pack case included in a conventional battery pack. [Figure 3] This shows the state in which a battery module is housed in the pack case of Figure 2 above. [Figure 4] 4 shows a cross section of a part of the side wall included in the pack case of FIGS. 2 and 3. FIG. [Figure 5] 1 is a perspective view of a pack case included in a battery pack according to a first embodiment of the present invention; [Figure 6] 1 shows a cross section of a base plate and a side wall including an insertion groove at an end of the base plate. [Figure 7] 1 shows a cross section of a portion of a support wall and a side wall. [Figure 8] 1 illustrates a battery module of the present invention. [Figure 9] The battery module is seated so that the support wall is adjacent to the connected side wall. [Figure 10] In order to show the connection between the support wall and the reinforcing plate, a cross section of the connection between the side wall, the support wall and the reinforcing plate is shown. [Figure 11] 10 illustrates a process in which a support wall and a reinforcing plate are coupled to a side wall included in a battery pack according to a second embodiment of the present invention. [Figure 12] 10 illustrates a process in which a support wall and a reinforcing plate are coupled to a side wall included in a battery pack according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before that, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concepts of the terms to best describe his own invention.

[0031] Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and there may be various equivalents and modifications that can replace them at the time of this application.

[0032] Furthermore, in the description of the present invention, if it is determined that a detailed description of related publicly known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0033] The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and therefore the shapes and sizes of components in the drawings may be exaggerated, omitted, or shown in a schematic manner for clearer explanation. Therefore, the sizes and proportions of each component do not completely reflect the actual sizes and proportions.

[0034] The present invention relates to a battery pack accommodating a battery module M. More specifically, the present invention relates to a battery pack accommodating a battery module M having reinforcing plates Pr on both sides thereof for supporting the side surfaces thereof, and the battery pack of the present invention is characterized by improving space efficiency by separately creating a space for a weld bead Bw generated in the welding process for fixing the battery module M.

[0035] 5 to 10 relate to a battery pack according to a first embodiment of the present invention, FIG. 11 relates to a battery pack according to a second embodiment of the present invention, and FIG. 12 relates to a battery pack according to a third embodiment of the present invention.

[0036] Hereinafter, each embodiment of the battery pack of the present invention will be described with reference to the above drawings.

[0037] (First embodiment) FIG. 5 is a perspective view of a pack case 1000 included in the battery pack according to the first embodiment of the present invention.

[0038] As shown in FIG. 5, the pack case 1000 of the present invention includes a base plate 100, a side wall 200, and a support wall 300.

[0039] The base plate 100 serves to support the lower portion of the battery module M housed in the pack case 1000.

[0040] The side walls 200 support the sides of the battery modules M housed in the pack case 1000 and protect the battery modules M from the external environment.

[0041] The side wall 200 is coupled along the edge of the base plate 100 .

[0042] When the side wall 200 is coupled to the base plate 100, a module area Am may be formed on the base plate 100, on which a plurality of battery modules M may be mounted.

[0043] The outer surface of the side wall 200 may be provided with terminals 400 electrically connected to the battery module M housed in the pack case 1000, and the battery pack may be electrically connected to an external device through the terminals 400.

[0044] More specifically, the side wall 200 includes a front frame 210 including a terminal 400 of the battery pack, a rear frame 220 disposed opposite the front frame 210, and a pair of side frames 230 coupled to the ends of the front frame 210 and the rear frame 220, respectively, on both sides of the base plate 100.

[0045] The pack case 1000 of the present invention may further include a main partition wall that is connected to the base plate 100 across the center.

[0046] The main partition wall may serve to protect conductive wires and bus bars inserted therein, or to partition the internal space of the pack case 1000 and separate the module regions Am.

[0047] The support wall 300 is connected to the inner surface of the side wall 200 .

[0048] The support wall 300 is coupled and fixed to the side wall 200 and the base plate 100, and serves to support and fix the battery module M of the present invention.

[0049] The side wall 200 and the support wall 300 included in the pack case 1000 may be made of a material such as aluminum, and the support wall 300 is joined to the side wall 200 by welding or the like.

[0050] The support wall 300 of the present invention includes a rib-shaped protruding connecting portion 310 on one side facing the side wall 200 .

[0051] The coupling part 310 is formed to extend along the longitudinal 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 the upper edge of the support wall 300 and protrudes forward.

[0052] As shown in FIG. 5, the side wall 200 includes an insertion groove 200h1 recessed inward so that the coupling portion 310 of the support wall 300 can be inserted therein.

[0053] That is, the support wall 300 is coupled to the side wall 200 by inserting the protruding coupling portion 310 into the insertion groove 200h1 of the side wall 200.

[0054] Specifically, as shown in FIG. 5, the insertion groove 200h1 is formed in at least one of the front frame 210 and the rear frame 220, and is formed to extend along the longitudinal direction of the front frame 210 or the rear frame 220.

[0055] The coupling portion 310 of the support wall 300 coupled to the insertion groove 200h1 is formed to extend along the longitudinal direction of the support wall 300 in correspondence with the insertion groove 200h1.

[0056] Preferably, the support wall 300 of the present invention can be coupled and fixed to the side wall 200 by welding the coupling portion 310 and the insertion groove 200h1 to each other.

[0057] FIG. 6 shows a cross section of the base plate 100 and the side wall 200 including the insertion groove 200h1 at the end of the base plate 100. As shown in FIG.

[0058] 6, the insertion groove 200h1 has an inwardly inclined surface at its upper portion, and therefore, when observed in cross section, the insertion groove 200h1 has a trapezoidal shape with an inclined surface on one side.

[0059] FIG. 7 shows a partial cross section of the support wall 300 and the side wall 200 that are joined together.

[0060] 7, an insertion groove 200h1 is formed on an inner surface of the side wall 200 coupled to an end of the base plate 100, and the support wall 300 is coupled to the side wall 200 such that the coupling portion 310 faces the insertion groove 200h1 and is inserted into the insertion groove 200h1. At this time, the coupling portion 310 is fitted into a space excluding the inclined surface of the insertion groove 200h1, and an empty space having a triangular cross section, i.e., a weld groove 200h2, is formed between the coupling portion 310 and the inclined surface. Thereafter, the coupling portion 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 formed by the welding may be filled into the weld groove 200h2.

[0061] Therefore, the support wall 300 can be tightly coupled to the side wall 200 by the welding groove 200h2 and can be firmly fixed by welding.

[0062] FIG. 8 shows a battery module M of the present invention.

[0063] As shown in FIG. 8, the battery module M includes a cell stack L in which a plurality of cells C are stacked in one direction, and a pair of reinforcing plates Pr coupled to support both outermost side surfaces of the cell stack L.

[0064] The reinforcing plate Pr includes a protrusion Pr1 that protrudes to form a step along the height direction of the battery module M. Specifically, the reinforcing plate Pr on one side of the battery module M includes the protrusion Pr1 on an upper part, and the reinforcing plate Pr on the other side includes the protrusion Pr1 on a lower part. Therefore, a pair of adjacent battery modules M can be coupled to each other by the interlocking reinforcing plates Pr.

[0065] FIG. 9 shows that the battery module M is seated adjacent to the side wall 200 to which the support wall 300 is coupled.

[0066] As shown in FIG. 9, the battery module M is mounted on the base plate 100 by closely contacting the support wall 300 with one side of the reinforcing plates Pr included on both sides, where the protrusion Pr1 is located at the top, facing the support wall 300.

[0067] 9, 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 so as to support and be coupled to the lower part of the protrusion Pr1 located on the upper part of the reinforcing plate Pr. Therefore, the battery module M is coupled to the support wall 300 by being positioned such that the lower part of the protrusion Pr1 of the reinforcing plate Pr is placed on the upper end of the support wall 300.

[0068] FIG. 10 shows a cross section of the bond between the side wall 200, the support wall 300, and the reinforcing plate Pr to illustrate the bond between the support wall 300 and the reinforcing plate Pr.

[0069] 10, the reinforcing plate Pr is coupled to the support wall 300 and the side wall 200 such that the protrusion Pr1 abuts against the inner side of the side wall 200 and is supported by the upper part of the support wall 300.

[0070] The battery module M coupled to the support wall 300 may be fixed to the pack case 1000 by bolts Bt. That is, as shown in Fig. 9, the battery module M may be fixed to the pack case 1000 by bolts Bt that penetrate the support wall 300 and the reinforcing plate Pr and are screwed to the base plate 100. At this time, since the weld bead Bw is filled in the weld groove 200h2 of the side wall 200, the reinforcing plate Pr can be tightly coupled to the side wall 200 and the support wall 300, thereby preventing waste of internal space in the pack case 1000.

[0071] 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 a well-known technology and does not constitute a main feature of the present invention, detailed description thereof will be omitted.

[0072] (Second embodiment) The support wall 300 of the present invention may be joined to the side wall 200 by welding the joining portion 310 and the insertion groove 200h1, and may also be welded to the base plate 100.

[0073] FIG. 11 illustrates a process in which a support wall 300 and a reinforcing plate Pr are coupled to a side wall 200 included in a battery pack according to a second embodiment of the present invention.

[0074] The side wall 200 according to the second embodiment is characterized in that it includes an inclined surface inclined inward at the edge of the lower end that is joined to the base plate 100, and includes an auxiliary groove 200h3 formed by the inclined surface.

[0075] The auxiliary groove 200h3 has a triangular cross section, and welding can be performed in the space of the auxiliary groove 200h3, that is, the lower end of the support wall 300, the lower end of the side wall 200, and the base plate 100 can be fixed to each other by welding within the auxiliary groove 200h3.

[0076] The weld bead Bw formed by the welding is filled only in the space of the auxiliary groove 200h3 so as not to prevent the support wall 300 from being tightly attached to the side wall 200.

[0077] (Third embodiment) The welding at the coupling portion 310 and the insertion groove 200h1 of the present invention can be carried out over a wider area.

[0078] FIG. 12 illustrates a process in which a support wall 300 and a reinforcing plate Pr are coupled to a side wall 200 included in a battery pack according to the third embodiment of the present invention.

[0079] The side wall 200 according to the third embodiment is characterized in that the upper and lower parts of the insertion groove 200h1 each include an inclined surface that is inclined inward.

[0080] 12, the coupling part 310 of the support wall 300 is fitted into the area of ​​the insertion groove 200h1 excluding the inclined surface. By fitting the coupling part 310 into the insertion groove 200h1, auxiliary grooves 200h3 are formed at the upper and lower parts of the coupling part 310 via the inclined surface.

[0081] The auxiliary grooves 200h3 have a triangular cross section, and welding can be performed in the spaces between the auxiliary grooves 200h3. That is, the support wall 300 can be welded to the side wall 200 through a larger space, and the support wall 300 can be more stably fixed to the side wall 200.

[0082] The weld bead Bw formed by the welding is filled only in the spaces of the auxiliary grooves 200h3 located at the upper and lower parts of the coupling portion 310 so as not to prevent the support wall 300 from being tightly attached to the side wall 200.

[0083] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0084] 10: (Prior Art) Battery Module 20: (Prior Art) Cell Stack 30: (Prior Art) Reinforcement Plate 40: (Prior Art) End Plate 50: (Conventional technology) Pack case 60: (Conventional technology) Base plate 70: (Prior Art) Sidewall 80: (Conventional) Main bulkhead 90: (Prior Art) Support Wall 100: (Prior Art) Joint 1000: Pack case 100: Base plate 200: Side wall 200h1: Insertion groove 200h2: Welded groove 200h3: Auxiliary groove 210: Front frame 220: Rear frame 230: Side frame 300: Support wall 310:Joining part 400: Terminal Am: Module Area Bt: Bolt Bw: Weld bead C: Cell L: Cell stack M: Battery module Pr: Reinforcement plate Pr1:Protrusion

Claims

1. A battery pack that houses a battery module, a pack case including a module area in which a battery module is mounted, The pack case is A base plate and a sidewall coupled along an edge of the base plate; a support wall coupled to an inner surface of the side wall; The support wall includes a connecting portion protruding in a rib shape on one side facing the side wall, The side wall includes an insertion groove formed therein so that the coupling portion of the support wall can be inserted therein; The side wall is a front frame including terminals for the battery pack; a rear frame disposed opposite the front frame, the support wall is coupled to at least one of the front frame and the rear frame; the battery module includes a cell stack in which a plurality of cells are stacked, and a pair of reinforcing plates coupled to support both side surfaces located at the outermost positions of the cell stack, The battery module accommodated in the pack case so as to abut against the front frame or the rear frame is fixed to the pack case by coupling one of the reinforcing plates to the support wall.

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

3. The side wall is a pair of side frames respectively coupled to the ends of the front frame and the rear frame on either side of the base plate; The battery pack according to claim 1 .

4. The insertion groove is formed to extend along the longitudinal direction of the front frame or the rear frame, The battery pack according to claim 1 , wherein the coupling portion of the support wall coupled to the insertion groove is formed to extend along the longitudinal direction of the support wall in correspondence with the insertion groove.

5. A battery pack that houses a battery module, a pack case including a module area in which a battery module is mounted, The pack case is A base plate and a sidewall coupled along an edge of the base plate; a support wall coupled to an inner surface of the side wall; The support wall includes a connecting portion protruding in a rib shape on one side facing the side wall, The side wall includes an insertion groove formed therein so that the coupling portion of the support wall can be inserted therein; The side wall is a front frame including terminals for the battery pack; a rear frame disposed opposite the front frame; a pair of side frames coupled to ends of the front frame and rear frame on both sides of a base plate, respectively; the support wall is coupled to at least one of the front frame and the rear frame; the battery module includes a cell stack in which a plurality of cells are stacked, and a pair of reinforcing plates coupled to support both side surfaces located at the outermost positions of the cell stack, The battery module accommodated in the pack case so as to abut against the front frame or the rear frame is fixed to the pack case by coupling one of the reinforcing plates to the support wall.

6. The battery pack according to claim 5 , wherein the battery module coupled to the support wall is fixed to the pack case by a bolt that passes through the coupled support wall and reinforcing plate and is screwed into a base plate.

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

8. the reinforcing plate included in the battery module includes a protrusion that protrudes to form a step along a height direction of the battery module, The battery pack of claim 5 , wherein the battery module is coupled to the support wall such that a lower portion of the protrusion of the reinforcing plate is placed on an upper end of the support wall.

9. The insertion groove includes an inclined surface inclined inward at an upper portion thereof, The coupling portion of the support wall is fitted into a space excluding the inclined surface of the insertion groove, The battery pack according to claim 1 , wherein a weld bead formed by welding fills a gap between the joint portion and the inclined surface.

10. The height of the support wall is less than the height of the side wall; The battery pack according to claim 1 , wherein the coupling portion is formed on an upper edge of the support wall.

11. the side wall includes an inclined surface inclined inward at a lower edge portion that is coupled to the base plate, an auxiliary groove formed by the inclined surface; The battery pack according to claim 1 , wherein the lower end of the support wall, the lower end of the side wall, and the base plate are fixed to one another within the auxiliary groove by welding.

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

13. the insertion groove includes inclined surfaces inclined inward at upper and lower portions, The coupling portion of the support wall is fitted into an area of ​​the insertion groove excluding the inclined surface, The battery pack according to claim 1 , wherein a weld bead formed by welding fills a gap between the joint portion and the inclined surface.

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