Battery pack

Abstract

A battery pack according to an aspect of the present disclosure is formed by storing a battery module in an exterior case. The exterior case comprises: a cylindrical case body having an opening; and a lid part which closes the opening of the case body. The lid part comprises: an inner lid connected to the opening of the case body; and an outer lid which is fixed to the inner lid and closes the opening of the case body. The inner lid is connected to an inner peripheral surface of the case body at the opening of the case body. The outer lid is fixed to an outer surface of the inner lid.

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack in which a battery module is disposed in a cylindrical outer case. [Background Art]

[0002] FIG. 5 is an exploded perspective view of a conventional battery pack. An outer case having a cylindrical case body has the advantage of enabling simple, efficient mass production while ensuring the case body has sufficient strength. In the outer case of this structure, a battery module is disposed inside the case body, and a lid is fixed to the opening of the case body. (See Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2011-134540 [Summary of the Invention]

[0004] In a battery pack in which openings at both ends of a cylindrical case body are closed by lid portions, as shown in FIG. 5, in order to fix the lid portion 94 to the case body 93, it is necessary to provide a fixing protrusion 96 having a female threaded hole 97 into which a set screw 95 passing through the lid portion 94 is screwed. Since the case body 93 shown in the drawing has the fixing protrusion 96 protruding from the inner surface, the fixing protrusion 96 restricts the internal volume. The battery pack 90 whose internal volume is restricted by the fixing protrusion 96 needs to have an increased outer dimensions of the case body 93 to accommodate a battery module 91 or the like of a specific outer shape, so that the energy density relative to the volume decreases. A battery pack can have a structure in which the fixing protrusion protrudes outward of the case body so that the fixing protrusion does not restrict the internal volume, but this structure has the disadvantage that the fixing protrusion increases the outer dimensions, thereby reducing the energy density relative to the volume.

[0005] The battery pack disclosed herein was developed with the aim of overcoming the above-mentioned drawbacks. One of the objectives of this disclosure is to provide a battery pack that can achieve a high energy density relative to its volume, which is an important characteristic for battery packs, by forming the case body into a cylindrical shape for efficient mass production, while also providing a structure that can close the opening without providing fixed protrusions on the inner or outer surface of the case body.

[0006] A battery pack according to one embodiment of the present disclosure comprises a battery module housed in an outer case. The outer case comprises a cylindrical case body having an opening and a lid portion that closes the opening of the case body. The lid portion comprises an inner lid connected to the opening of the case body and an outer lid fixed to the inner lid and closing the opening of the case body. The inner lid is connected to the inner circumferential surface of the case body at the opening of the case body. The outer lid is fixed to the outer surface of the inner lid.

[0007] The battery pack described above has a lid that closes the opening of the cylindrical case body. This lid consists of an inner lid connected to the inner circumferential surface of the case body and an outer lid fixed to the outer surface of the inner lid. Since the outer lid closes the opening of the case body, it is not necessary to provide fixing protrusions on the inner or outer circumferential surfaces of the opening of the cylindrical case body to secure the lid, as is the case with conventional battery packs. As a result, the case body can be made cylindrical for efficient mass production, while also achieving a high energy density relative to volume, which is an important characteristic for battery packs.

[0008] A battery pack according to another aspect of the present disclosure further includes a gasket sandwiched between the outer lid and the opening of the case body to seal the opening of the case body in a waterproof manner, the inner lid is connected to the opening of the case body in a non-waterproof manner, and the outer lid is shaped to be able to close the opening of the case body, and the gasket is pressed against the case body by the outer lid to seal the opening of the case body in a waterproof manner.

[0009] The above battery pack features an inner lid connected to the opening of the case body in a non-waterproof structure, with an outer lid fixed to the outer surface of the inner lid. The outer lid then presses a gasket against the case body, and the gasket and outer lid together seal the opening of the case body in a waterproof structure. This eliminates the need for fixing protrusions to secure the lid in a watertight structure at the opening of the cylindrical case body, as in conventional battery packs, and has the advantage of being able to seal the opening of the case body in a waterproof structure while maintaining a compact external shape.

[0010] In other embodiments of the present disclosure, the battery pack can have a gasket sandwiched between the opening edge of the case body and the opposing surface of the outer lid.

[0011] The battery packs described above have the advantage of securely connecting the outer lid and the case body in a waterproof structure via the gasket, because the outer lid is fixed to the inner lid, and the gasket is pressed against the case body via the outer lid.

[0012] Battery packs according to other embodiments of this disclosure can be connected by a locking structure that allows the inner lid to be inserted into and locked to the inner circumferential surface of the case body.

[0013] The battery pack described above has the advantage of being able to connect the inner lid to the case body with an extremely simple structure, as the inner lid is inserted into the inner circumference of the case body and connected with a locking mechanism. Furthermore, the locking mechanism ensures that the inner lid is connected to the case body in a fixed position, precisely and without any misalignment.

[0014] In another aspect of the present disclosure, the battery pack has a case body having a plurality of locking recesses on the inner circumferential surface of the opening, and the inner lid has a plurality of locking protrusions that protrude from the outer circumference and are guided into the locking recesses, and the inner lid can be connected to a fixed position on the case body by guiding the plurality of locking protrusions into the plurality of locking recesses, respectively.

[0015] The above battery pack has the advantage that the inner lid can be connected to the case body in a simple process of inserting it into the inside of the case body. This is because the inner lid is provided with multiple locking recesses on the inner surface of the case body, and multiple locking protrusions are provided on the outer circumference of the outer lid that are guided into these locking recesses, thereby connecting the inner lid to the fixed position on the case body.

[0016] In another aspect of the present disclosure, the battery pack has an inner lid having a peripheral wall that is inserted into the inner peripheral surface of an opening in the case body, and a plurality of locking protrusions are arranged on the outer peripheral surface of the peripheral wall, and the plurality of locking protrusions are guided into a plurality of locking recesses, thereby connecting the inner lid to the inner peripheral surface of the case body.

[0017] The battery pack described above has a peripheral wall on the inner lid, with locking protrusions protruding from the outer surface of this peripheral wall. By sliding the peripheral wall along the inner surface of the case body, the inner lid can be held parallel to the opening of the case body and moved inward from the opening. Therefore, the multiple locking protrusions on the peripheral wall of the inner lid can be guided together into multiple locking recesses on the inner surface of the case body, allowing for easy connection to the case body with a locking structure.

[0018] In other embodiments of the present disclosure, the battery pack has a peripheral wall made of an elastically deformable plate material, and the locking projection can be positioned in the locking recess by elastically deforming the peripheral wall.

[0019] The battery pack described above has the advantage that the peripheral wall on which the locking projection is provided undergoes elastic deformation, allowing the locking projection to slide smoothly along the inner surface of the case body, guiding it into the locking recess, and enabling the inner lid to be connected to the case body in a fixed position with a locking structure.

[0020] In other embodiments of the present disclosure, the battery pack can be connected to the case body by welding or bonding the inner lid.

[0021] In the battery pack described above, since the inner lid and the case body are connected by welding or adhesion, it has the advantage that the inner lid and the case body can be reliably connected over a wide area or a long region.

[0022] In a battery pack according to another aspect of the present disclosure, an outer lid can be connected to an inner lid via a set screw that penetrates the waterproof structure and is screwed into the inner lid.

[0023] The battery pack described above has the advantages that the outer lid can be easily connected to the inner lid, and in the step of fixing the outer lid to the inner lid, the gasket can be pressed against the case body to achieve reliable connection with a waterproof structure.

[0024] In a battery pack according to another aspect of the present disclosure, the outer lid has a recess on a surface thereof, and a screw head of the set screw can be disposed in the recess.

[0025] In the battery pack described above, a recess is provided in the outer lid, and the screw head of the set screw is disposed therein, so that the set screw does not protrude from the surface of the outer lid, or the protrusion amount can be reduced, and the outer lid can be fixed to the inner lid with such an advantage.

[0026] In a battery pack according to another aspect of the present disclosure, the case body can be made of aluminum processed into a cylindrical shape.

[0027] The battery pack described above has the advantage that the case body can be mass-produced efficiently by drawing or extruding aluminum. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [Figure 1] FIG. 1 is a perspective view of a battery pack according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view of the battery pack shown in FIG. 1. [Figure 3] FIG. 3 is an enlarged exploded perspective view showing an outer case of the battery pack shown in FIG. 2. [Figure 4]Figure 4 is a large, enlarged cross-sectional view of the battery pack shown in Figure 1. [Figure 5] Figure 5 is a disassembled perspective view of a conventional battery pack. [Modes for carrying out the invention]

[0029] The present disclosure will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of the disclosure with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components.

[0030] Furthermore, the embodiments described below illustrate specific examples of the technical concept of the present invention and do not limit the present invention to those described below. Also, the dimensions, materials, shapes, relative arrangements, etc., of the components described below are intended to be illustrative, and not to limit the scope of the present invention unless otherwise specified. Moreover, the content described in one embodiment or example is applicable to other embodiments and examples. Additionally, the size and positional relationships of the members shown in the drawings may be exaggerated for clarity.

[0031] (Embodiment 1) The battery pack 100 shown in Figures 1 to 4 has a battery module 1 housed in an outer case 2. The battery module 1 comprises a battery block in which multiple individual cells are connected in series or parallel, and a circuit board connected to this battery block. The battery block connects multiple individual cells in series or parallel to achieve the required charge and discharge capacity, and each individual cell is positioned in a fixed position using a battery holder. The circuit board is connected to the battery block and implements a protection circuit that controls the charging and discharging of the battery block. The individual cells are, for example, secondary batteries such as lithium-ion batteries. A battery module 1 using lithium-ion secondary batteries as the individual cells can achieve a large charge and discharge capacity relative to its capacity and weight. However, the individual cells of the battery block are not limited to lithium-ion secondary batteries; all secondary batteries currently in use or to be developed in the future, such as all-solid-state batteries, can also be used.

[0032] (Outer case 2) The outer casing 2 comprises a cylindrical case body 3 and a lid 4 that closes the opening 3A of the case body 3. The lid 4 consists of an inner lid 5 connected to the opening 3A of the case body 3 and an outer lid 6 fixed to the outer surface 5A of the inner lid 5 to close the opening 3A of the case body 3. The inner lid 5 is connected to the inner circumferential surface of the opening 3A of the case body 3. The outer lid 6 is fixed to the outer surface 5A of the inner lid 5 to close the opening 3A of the case body 3. Furthermore, in the outer casing 2 shown in Figures 1 to 4, a gasket 7 is sandwiched between the outer lid 6 and the case body 3, and the opening 3A of the case body 3 is connected to the lid 4 in a waterproof structure. The waterproof outer casing 2 can ensure higher safety by preventing various problems caused by water ingress, such as leakage current and short-circuit current due to a decrease in insulation resistance.

[0033] (Case body 3) The case body 3 can preferably be manufactured by forming a cylindrical shape from metal or plastic using drawing or extrusion. The cylindrical case body 3 can be efficiently mass-produced by forming it into a long cylindrical shape and then cutting it to a predetermined length. Since the cylindrical case body 3 formed by drawing or extrusion can have the same cross-sectional shape, it has the advantage that the inner lid 5, described later, can be smoothly inserted and connected by sliding it onto the inner circumferential surface of the opening 3A. The metal case body 3 can preferably be manufactured by drawing or extrusion from aluminum or an aluminum alloy. In addition to its excellent impact strength, the metal case body 3 has favorable thermal conductivity characteristics that allow it to efficiently dissipate heat from internal heat-generating components to the outside. This disclosure does not specify that the metal of the case body 3 is aluminum, and it can also be manufactured from metals other than aluminum. For example, the case body 3 can be made from a metal such as magnesium to reduce weight and achieve a high energy density relative to weight while maintaining excellent impact strength. Furthermore, the case body 3 can be made of plastic, and a stronger case body 3 can be formed by embedding reinforcing fibers such as glass fibers or carbon fibers.

[0034] The case body 3 shown in Figures 2 to 4 has a locking recess 8 on the inner circumferential surface of the opening 3A in order to connect the inner lid 5 to a fixed position with a locking structure. The locking recess 8 guides the locking projection 9 provided on the outer circumferential surface of the inner lid 5 into a fitted state, thereby connecting the inner lid 5 to the case body 3 without misalignment. The fitting structure between the locking recess 8 and the locking projection 9 can be realized with a shape that allows the locking projection 9 to be guided into the locking recess 8 without any gaps. In order to guide the locking projection 9 into the locking recess 8 with a fitting structure, the gap between the locking recess 8 and the guided locking projection 9 can be realized with, for example, 0.2 mm or less, preferably 0.1 mm or less. The locking recess 8 can smoothly guide the locking projection 9 by having a chamfered shape at the opening edge or by having a tapered shape that increases the opening area toward the opening 3A.

[0035] The locking recess 8 is provided on the inner circumferential surface without penetrating the case body 3. This locking recess 8 can be provided, for example, by press working on the inner surface 3C (inner circumferential surface 3D) of the cylindrical case body 3. In this processing method, a press die with a protrusion for forming the locking recess 8 is inserted into the cylindrical case body 3, both ends of the press die are made to protrude from the openings 3A at both ends of the case body 3, and the locking recess 8 can be provided by pressing these protrusions with a press mechanism. However, this disclosure does not specify a processing method for providing the locking recess 8 on the inner circumferential surface of the case body 3, and all other methods that can provide the locking recess 8 on the inner circumferential surface of the case body 3 can be employed.

[0036] The rectangular cylindrical case body 3 has locking recesses 8 on the inner surface of each side forming the rectangle, securely and stably connecting the inner lid 5 with a locking structure. In Figures 2 to 4, the case body 3 has locking recesses 8 at opposing positions on the inner surface. The rectangular cylindrical case body 3, with its four mutually orthogonal inner surfaces, has multiple locking recesses 8 on each surface, allowing the inner lid 5 to be connected to the case body 3 more accurately and without misalignment, and holding the inner lid 5 in a position perpendicular to the axial direction of the case body 3 (horizontal in the figures). In Figure 3, the case body 3 has more locking recesses 8 on the wider surface 3a located on the longer side of the rectangle than on the narrower surface 3b located on the shorter side. This structure allows the rectangular inner lid 5 to be connected in a fixed position, holding it in a position perpendicular to the axial direction (horizontal in the figures). By increasing the number of locking recesses 8 arranged on the same surface of each inner surface, the inner lid 5 can be firmly connected to the fixed position of the case body 3 in a position perpendicular to the axial direction. However, by reducing the number of locking recesses 8, the process of connecting the inner lid 5 and the case body 3 can be made more efficient. Therefore, the number of locking recesses 8 is set to the optimal number considering the size and bending strength of the inner lid 5.

[0037] The case body 3 shown in Figures 1 to 3 is molded into a rectangular tubular shape, but the tubular shape of the case body 3 is not limited to a rectangular cross-section; it can also be elliptical, circular, or a polygonal tubular shape with curved corners. Case bodies 3 of these shapes can be connected to a fixed position by providing locking recesses 8 at predetermined intervals to hold the inner lid 5 in a position perpendicular to the axial direction.

[0038] (Inner lid 5) The inner lid 5 is connected to the inner circumferential surface of the opening 3A of the case body 3. The inner lid 5 shown in Figures 2 to 4 is connected to the case body 3 by a locking structure. The inner lid 5, which is connected to the case body 3 by a locking structure, has the advantage of being able to be inserted into the inner circumferential surface of the opening 3A of the case body 3 and connected to a fixed position without misalignment.

[0039] The inner lid 5, which is connected to the case body 3 by a locking structure, is provided with a plurality of locking protrusions 9 that protrude from the outer circumference and are guided into locking recesses 8 on the inner circumferential surface of the case body 3. Since the locking protrusions 9 are guided into the locking recesses 8 and connect the inner lid 5 to the fixed position on the case body 3, as described above, the outer shape of the locking protrusions 9 is preferably such that it is guided into the locking recesses 8 by a fitting structure.

[0040] The waterproof outer case 2 achieves its waterproof structure by sandwiching a gasket 7 between the outer lid 6 and the case body 3, rather than by achieving waterproofness through the inner lid 5 and the case body 3. The inner lid 5 does not need to be connected to the case body 3 in a waterproof structure, so it can be easily connected by locking to the inner surface of the case body 3 in a non-waterproof structure without achieving waterproofness. The inner lid 5 is a component for fixing the outer lid 6 to the opening 3A of the case body 3, and is not required to have any special feature that closes the opening 3A of the case body 3 itself. Therefore, the inner lid 5 can be easily connected to the case body 3 in a locking structure, but the connection structure is not limited to a locking structure, and the inner lid 5 can be connected to the case body 3 in any other structure that can connect it. For example, the inner lid 5 can be connected to the case body 3 by adhesive, or the outer circumference of the inner lid 5 and the inner circumference of the case body 3 can be welded together.

[0041] The inner lid 5 in Figures 3 and 4 is formed by press-forming a metal plate to create a box shape with a peripheral wall 11 around the main plate portion 10 that is inserted into the inner circumferential surface of the opening 3A of the case body 3, and has multiple locking protrusions 9 on the outer circumferential surface of the peripheral wall 11. This inner lid 5 is made by press-forming a flat metal plate to create the locking protrusions 9, then cutting it to a predetermined outer shape, and finally bending the periphery of the main plate portion 10 at a right angle to form the peripheral wall 11. With this shape, the inner lid 5 can be efficiently mass-produced with accurate dimensions and shape through the pressing, cutting, and bending processes. Furthermore, the inner lid 5 can slide along the inner surface 3C (inner circumferential surface 3D) of the case body 3 with its peripheral wall 11, holding the inner lid 5 in a position parallel to the opening 3A of the case body 3, and moving inward from the opening 3A to guide the locking protrusions 9 into the locking recesses 8. Therefore, the inner lid 5 has the advantage of being able to be positioned in a fixed location on the case body 3 by guiding the multiple locking protrusions 9 provided on the peripheral wall 11 of the inner lid 5 together into the respective locking recesses 8 on the inner peripheral surface 3D of the case body 3. Furthermore, since the inside of the peripheral wall 11 of the inner lid 5 is used as the placement space for the battery module 1, the height of the peripheral wall 11 can be increased (increased vertically in the figure) without narrowing the placement space, and the inner lid 5 can be moved and connected along the inner peripheral surface 3D of the case body 3 while being held in a horizontal position.

[0042] Furthermore, the inner lid 5 described above has a metal plate of peripheral wall 11 with a thickness that allows for elastic deformation, for example, 2 mm or less, so that the peripheral wall 11 with the locking projection 9 slides smoothly along the inner peripheral surface 3D of the case body 3, guiding the locking projection 9 into the locking recess 8. In addition, the elastic restoring force of the peripheral wall 11 holds the locking projection 9, guided into the locking recess 8, in a state where it cannot come out of the locking recess 8, thereby firmly connecting the inner lid 5 to the case body 3. In the inner lid 5, where the peripheral wall 11 is elastically deformable, the pressure that the locking projection 9 presses against the inner peripheral surface 3D of the case body 3 decreases as the peripheral wall 11 elastically deforms. The frictional resistance of the locking projection 9 with the inner peripheral surface 3D of the case body 3 decreases as the pressure pressing against the inner peripheral surface 3D decreases. This is because frictional resistance increases in proportion to the pressing force. The locking projection 9 with reduced frictional resistance can slide smoothly along the inner peripheral surface 3D of the case body 3 and be quickly guided into the locking recess 8. Furthermore, the locking projection 9 guided by the locking recess 8 is held in the locking recess 8 by elastic restoring force, allowing the inner lid 5 to be positioned in its fixed location on the case body 3. In other words, the inner lid 5 of this structure achieves the ideal characteristic of smoothly connecting to the fixed location on the case body 3 and remaining in its fixed location on the case body 3 without coming loose while connected. This feature is extremely important in the outer case 2, which guides numerous locking projections 9 into the locking recess 8 in order to reliably connect the large inner lid 5 to the case body 3. This is because providing numerous locking projections 9 and locking recesses 8 increases the frictional resistance between each locking projection 9 and the inner circumferential surface 3D of the case body 3, making smooth connection difficult.

[0043] Furthermore, the inner cover 5 is provided with a screw hole 12 for screwing in a set screw 13 to secure the outer cover 6. The inner cover 5 shown in Figures 3 and 4 is located on the outer circumference of the main plate portion 10, and the screw hole 12 is provided opposite the position where the set screw 13, which is screwed into the outer cover 6, is screwed. This screw hole 12 is, for example, a burred screw hole so that the set screw 13 screwed into it can be firmly secured.

[0044] (Outer cover 6) The outer cover 6 is fixed to the outer surface 5A of the inner cover 5 and closes the opening 3A of the case body 3. The outer cover 6 can be made of plastic or metal in the shape of a plate that can close the opening 3A of the case body 3. In Figures 1 to 4, the outer cover 6 is shaped to match the outer edge of the cylindrical case body 3, so that the outer cover 6 and the outer edge of the case body 3 are on the same plane. The outer cover 6 can be fixed to the inner cover 5 via a set screw 13 that penetrates the waterproof structure. The set screw 13 has a non-circular fitting hole in the center of the screw head, such as a hexagon, star shape, or ellipse, so that a screwdriver or the like can be inserted into the fitting hole and rotated to screw it into the inner cover 5. The set screw 13 penetrates the outer cover 6 with a ring-shaped packing 14 sandwiched between the screw head and the surface of the outer cover 6, and the screw portion is screwed into the screw hole 12 of the inner cover 5 to fix the outer cover 6 to the inner cover 5. The set screw 13, which does not connect the outer lid 6 in the waterproof structure, passes through the outer lid 6 without using a gasket 14 and is screwed into the inner lid 5.

[0045] The outer lid 6 in Figures 1 to 4 has a recess 15 on its outer surface 6A for positioning the screw head of the set screw 13. The outer lid 6 shown in the figures has a rectangular recess 15 in the area excluding the outer peripheral edge. The recess 15 is deeper than the height of the screw head, so that the outer lid 6 can be fixed to the inner lid 5 without the screw head protruding from the surface of the outer lid 6. The recess 15 has a through hole 16 through which the set screw 13 is inserted. The through hole 16 is on the outer peripheral edge of the recess 15, and the set screw 13 inserted into this hole fixes the outer peripheral edge of the outer lid 6 to the inner lid 5, so that the outer peripheral edge of the outer lid 6 is in close contact with the opening 3A of the case body 3. The outer lid 6 with the recess 15 in the area excluding the outer peripheral edge can fix the outer lid 6 to the inner lid 5 without the screw head of the set screw 13 protruding from the surface, or with a small amount of protrusion. In addition, the outer peripheral edge of the outer lid 6 is made thicker to increase its bending strength, so that it can be securely fixed in close contact with the opening 3A of the case body 3. Furthermore, the recess 15 allows for weight reduction of the outer cover 6. A battery pack 100 with a lighter outer cover 6 can achieve sufficient strength by using a metal outer cover 6 such as aluminum, and while achieving excellent heat dissipation characteristics, it can also lighten the outer case 2 and increase the energy density relative to its weight. The outer cover 6 can be made of plastic as well as metal, and even a plastic outer cover 6 can be made lighter and have a higher energy density relative to its weight by providing the recess 15 on the outer surface 6A.

[0046] The outer lid 6 in Figure 4 is provided with a guide groove 17 that guides the gasket 7, which is used to secure the lid to the case body 3 in a waterproof manner, into place. The guide groove 17 is located on the surface opposite to the open end face 3B of the case body 3. The depth of the guide groove 17 is smaller than the thickness and outer diameter of the gasket 7, and when the outer lid 6 is fixed to the inner lid 5, it is compressed and tightly adheres to the outer lid 6 and the open end face 3B of the case body 3.

[0047] (Gasket 7) The gasket 7 is a ring-shaped material made of an elastic material such as elastomer or rubber, or a material that, when pressed, adheres tightly to the outer lid 6 and the open end surface 3B of the case body 3 to create a waterproof structure. It is placed in the guide groove 17 of the outer lid 6 and elastically deforms when pressed against the case body 3 by the outer lid 6. The gasket 7 is an O-ring made of elastomer or rubber, or a sheet that, when pressed, adheres tightly to the opposing surface of the waterproof structure. With the outer lid 6 fixed to the inner lid 5, the gasket 7 adheres tightly to the opposing surfaces of the outer lid 6 and the case body 3 to seal the outer case 2 into a waterproof structure.

[0048] The outer case 2 shown in Figure 4 is equipped with a gasket 7 that is sandwiched between the outer lid 6 and the opening edge of the case body 3 to seal the opening 3A of the case body 3 in a waterproof manner. In this battery pack 100, the inner lid 5 is connected to the opening 3A of the case body 3 in a non-waterproof manner, and the outer lid 6 is made to have an outer shape that can close the opening 3A of the case body 3, preferably approximately equal to the outer shape of the case body 3, and the outer lid 6 presses the gasket 7 against the opening edge of the case body 3. The rubber-like elastic gasket 7, pressed by the outer lid 6, elastically deforms in the direction of compression, and adheres tightly to the outer circumference of the outer lid 6 and the opening end face 3B of the case body 3, thereby sealing the opening 3A of the case body 3 in a waterproof manner. [Industrial applicability]

[0049] This disclosure can be suitably used as a battery pack in which a battery module is arranged in a cylindrical outer case, thereby increasing the energy density relative to the volume. [Explanation of Symbols]

[0050] 100 Battery Pack 1 Battery Module 2. Outer case 3. Case body 3A opening 3B Opening end surface 3a Wide surface 3b Narrow side 4 Lid 5. Inner lid 6. Outer lid 7 Gasket 8 Locking recess 9 Locking projection 10 Main body plate section 11 Peripheral wall 12 screw holes 13 Set screws 14 Gasket 15 recesses 16 through holes 17 Guide groove 90 Battery Pack 91 Battery Module 93 Case body 94 Lid 95 Set screw 96 Fixed protrusion 97 Female screw hole

Claims

1. A battery pack having a battery module built into an outer casing, The aforementioned outer casing is A cylindrical case body having an opening, It consists of a lid portion that closes the opening of the case body, The aforementioned lid portion is An inner lid connected to the opening of the case body, It consists of an outer lid that is fixed to the inner lid and closes the opening of the case body, The inner lid is connected to the inner circumferential surface of the case body at the opening of the case body. The outer cover is fixed to the outer surface of the inner cover, The case further comprises a gasket sandwiched between the outer lid and the opening of the case body, which seals the opening of the case body in a waterproof manner. The inner lid is connected to the opening of the case body in a non-waterproof manner. The outer lid has an outer shape configured to close the opening of the case body, The gasket is configured to be pressed against the case body by the outer lid, thereby sealing the opening of the case body in a waterproof manner, in a battery pack.

2. A battery pack according to claim 1, A battery pack in which the gasket is sandwiched between the opening edge of the case body and the opposing surface of the outer lid.

3. A battery pack according to claim 1, A battery pack in which the inner lid is connected by a locking structure that inserts into and locks the inner circumferential surface of the case body.

4. The battery pack according to claim 3, The case body has a plurality of locking recesses provided on the inner circumferential surface of the opening, The inner cover has a plurality of locking protrusions that protrude from the outer circumference of the inner cover and are guided into the locking recess, A battery pack in which the plurality of locking protrusions are guided into the plurality of locking recesses, respectively, and the inner lid is connected to the case body in a fixed position.

5. The battery pack according to claim 4, The inner lid has a peripheral wall that is inserted into the inner circumferential surface from the opening of the case body, The plurality of locking protrusions are arranged on the outer circumferential surface of the peripheral wall of the inner lid, A battery pack in which the plurality of locking protrusions are guided into the plurality of locking recesses, respectively, and the inner lid is connected to the inner circumferential surface of the case body.

6. The battery pack according to claim 5, The peripheral wall is made of a plate material that can be elastically deformed, A battery pack in which the peripheral wall is elastically deformed and the locking projection is positioned in the locking recess.

7. A battery pack according to any one of claims 1 to 6, A battery pack in which the inner lid is welded or bonded to the case body.

8. A battery pack according to any one of claims 1 to 6, A battery pack in which the outer cover is connected to the inner cover via a set screw that penetrates the inner cover and is screwed into the inner cover, with the outer cover having a waterproof structure.

9. The battery pack according to claim 8, The outer cover has a recess on its surface, A battery pack in which the screw head of the retaining screw is positioned in the recess of the outer cover.

10. A battery pack according to claim 1, The aforementioned case body is a battery pack made of aluminum processed into a cylindrical shape.

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