Battery pack

Abstract

This invention achieves stable holding of a core pack while also making assembly of the core pack to an exterior case easier using a simple configuration. A battery pack 100 includes: a core pack 2 including a plurality of battery cells 1; and an exterior case 10 for housing the core pack 2 in an internal space 13. The exterior case 10 has a plurality of recesses 30 on a wall surface 20. The plurality of recesses 30 form a plurality of protrusions 40 protruding to the internal space 13 side, and the core pack 2 is supported by the protrusions 40.

Description

Battery pack

[0001] The present disclosure relates to a battery pack.

[0002] Battery packs that house a plurality of rechargeable battery cells, such as lithium-ion secondary batteries, inside an exterior case to power electrical devices are used for a variety of purposes (see, for example, Patent Documents 1 and 2). Such battery packs require a structure that allows the exterior case to stably hold a core pack while also facilitating assembly of the core pack to the exterior case, but achieving both goals simultaneously has been a challenge.

[0003] Japanese Patent No. 7216530 JP 2022-124214 A

[0004] One object of the present disclosure is to provide a battery pack that can stably hold a core pack with a simple configuration while facilitating assembly of the core pack to an exterior case. Another object is to provide a battery pack with improved rigidity. Note that the description of these objects and objects of the present disclosure does not preclude the existence of other objects and objects. Furthermore, the embodiments of the present disclosure do not necessarily solve all of these objects, and other objects may be extracted from the description of the specification, drawings, and claims of the present disclosure.

[0005] A battery pack according to one embodiment of the present disclosure is a battery pack comprising a core pack containing a plurality of battery cells and an outer case that houses the core pack in an internal space, wherein the outer case has a plurality of recesses on the outer surface of the wall, and the plurality of recesses are configured to support the core pack with protrusions that protrude into the internal space.

[0006] The configuration of one embodiment of the present disclosure has the advantage that the core pack can be stably held with a simple configuration, and the core pack can be easily assembled to the outer case. Furthermore, the above configuration has the advantage that the rigidity of the battery pack can be improved.

[0007] 1 is a schematic perspective view showing a battery pack according to embodiment 1. FIG. 2 is a schematic perspective view of the battery pack of FIG. 1 as seen from the rear side. FIG. 3 is a schematic exploded perspective view of an exterior case of the battery pack. FIG. 4 is a schematic perspective view of a core pack, a protective sheet, and an inner bag. FIG. 5 is a schematic exploded perspective view of the core pack. FIG. 6 is a schematic perspective view of an upper case. FIG. 7 is a schematic perspective view of a lower case. FIG. 8 is a schematic view showing the inner surface of a side surface (longitudinal side surface 22) of the battery pack. FIG. 9 is a schematic view showing the inner surface of another side surface (end surface 22a) of the battery pack. FIG. 1 is a horizontal cross-sectional view taken along line X-X in FIG. 1. FIG. 10 is an enlarged cross-sectional view of a main portion of a screw boss. FIG. 11 is a vertical cross-sectional view taken along line XII-XII in FIG. 2.

[0008] The embodiments of the present disclosure may be specified by the following configurations and features: A battery pack according to an embodiment of the present disclosure includes a core pack including a plurality of battery cells and an exterior case that houses the core pack in an interior space, the exterior case having a plurality of recesses on the outer surface of the wall, the plurality of recesses forming a plurality of ridges that protrude into the interior space and support the core pack with the ridges.

[0009] The above configuration has the advantage of being able to stably hold the core pack with a simple structure while facilitating assembly of the core pack to the exterior case. This is because the exterior case has multiple recesses on the outer surface of the wall, which form ridges that protrude into the interior space and support the core pack. The above configuration also has the advantage of being able to improve the rigidity of the battery pack. This is because the multiple recesses and ridges on the wall of the exterior case have an uneven shape that improves the strength and rigidity of the exterior case, thereby improving the vibration resistance and vibration resistance of the battery pack.

[0010] The above configuration has the advantage of being simple and capable of both stably holding the core pack and facilitating assembly of the core pack to the outer case. This is because the simple configuration in which the recessed ridges on the outer surface of the wall form multiple ridges that protrude into the interior space of the outer case allows the contact area of ​​the ridges with the core pack to be appropriately set and adjusted. The ridges have a large contact area with the core pack and contact it surface-to-surface, allowing for stable holding of the core pack while protecting it. The elasticity of the outer case due to the uneven shape of the recessed ridges and ridges prevents damage to the core pack due to vibration, impact, etc. Furthermore, the multiple ridges formed by the multiple recessed ridges can stably hold the core pack at spaced positions. Furthermore, the multiple ridges at spaced positions provide gaps between the core pack and contacting parts, such as the inner surface of the outer case, allowing the contact area with the core pack to be adjusted, facilitating assembly of the core pack to the outer case. Furthermore, the above configuration allows for a wide degree of design freedom in terms of the shape, size, and placement of the multiple recesses and protrusions on the wall surface, making it possible to accommodate the shapes and placement of the core pack and components. The above configuration has the advantage of being able to achieve the features described in this disclosure without substantially increasing the external size of the exterior case. This is because the exterior case has recesses that are recessed inward from the outer surface of the wall, and the recesses form protrusions that protrude into the interior space, without having any portions that protrude outward from the wall surface.

[0011] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure has a plurality of ridges provided at the center and end of the wall surface, and the width (w) of the ridges at the end can be smaller than that of the ridges at the center. This configuration has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the outer case. This configuration also has the advantage of improving the rigidity of the battery pack. This is because the relatively wide ridges at the center can stably hold the core pack through surface contact, and the relatively narrow ridges at the end can facilitate insertion and installation of the core pack from the end side. Furthermore, in addition to the uneven shape of the grooves and ridges, the relatively narrow ridges at the end provided at the end of the wall surface near the corner of the outer case can more effectively prevent and suppress deformation, distortion, and twisting of the outer case.

[0012] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure has an outer case formed by joining an upper case and a lower case, and the outer case has screw bosses for fastening screws joining the upper case and the lower case, and the screw bosses can be provided between adjacent ridges. This configuration has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the outer case. The above configuration also has the advantage of improving the rigidity of the battery pack. This is because the screw bosses are provided between adjacent ridges, allowing the upper case and the lower case to be reliably screwed together without misalignment, and the multiple ridges are arranged closely together, achieving both stable holding of the core pack and easy assembly of the core pack to the outer case. Furthermore, the uneven shape and thickness of the wall surface formed by the multiple ridges and screw bosses can prevent and suppress deformation, distortion, and twisting of the outer case.

[0013] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure can have a screw boss height (h) that is lower than a ridge height (H). This configuration has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the exterior case. The above configuration also has the advantage of being able to improve the rigidity of the battery pack. This is because the screw boss stably holds the core pack with the ridge, does not interfere with assembly of the core pack to the exterior case, and can prevent the screw boss from coming into contact with the core pack or inner bag housed inside, causing friction and damage due to vibration or impact.

[0014] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure may have a plurality of ridges arranged separately, and the outer case may have an inner groove between adjacent ridges on the inner surface of the wall. This configuration has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the outer case. The above configuration also has the advantage of improving the rigidity of the battery pack. This is because providing an inner groove between adjacent ridges on the inner surface of the outer case allows the contact area of ​​the ridges toward the core pack to be appropriately set and adjusted, thereby enabling stable holding of the core pack while avoiding difficulties in assembling the core pack to the outer case. Furthermore, the uneven shape of the wall formed by the plurality of ridges and the inner groove can prevent and suppress deformation, distortion, and twisting of the outer case.

[0015] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure has a gas flow path formed in the inner groove, which can communicate with the end space formed between the inner surface of the exterior case and the discharge end face of the battery cell. The above configuration has the advantage of improving the safety of the battery pack. By forming a gas flow path in the inner groove and further communicating the gas flow path with the end space, the smooth diffusion of ejected matter such as gas ejected from the discharge end face of the battery cell in the event of an abnormality can be promoted, the diffusion area can be expanded, and the thermal energy and kinetic energy of the ejected matter can be reduced and attenuated.

[0016] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure has an outer case that can have multiple inner grooves arranged at intersecting positions. This configuration has the advantage of being able to stably hold a core pack with a simple configuration while facilitating assembly of the core pack to the outer case. The above configuration also has the advantage of improving the rigidity of the battery pack. This is because the ridges arranged along the inner grooves can stably hold the core pack, and the uneven shape of the multiple inner grooves arranged at intersecting positions and in intersecting orientations can appropriately set and adjust the contact area of ​​the ridges on the core pack side, thereby stably holding the core pack while avoiding difficulties in assembling the core pack to the outer case, and preventing and suppressing deformation, distortion, and twisting of the outer case. Furthermore, the above configuration has the advantage that the multiple inner grooves arranged at intersecting positions and in intersecting orientations can promote smooth diffusion of ejected material, expanding the diffusion area and improving the safety of the battery pack.

[0017] In addition to the above configuration, a battery pack according to another embodiment of the present disclosure may have an outer case including an upper case and a lower case joined to the upper case, and the plurality of ridges may be formed separately on the upper case and the lower case, avoiding the joint between the upper case and the lower case. This configuration has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the outer case. The above configuration also has the advantage of improving the rigidity of the battery pack. This is because the plurality of ridges are separated and spaced apart on the upper case and the lower case, respectively, allowing for stable holding of the core pack and appropriate setting and adjustment of the contact area of ​​the ridges on the core pack side. Furthermore, the ridges are not provided at the joint between the upper case and the lower case, and an inner groove can be provided along the joint, facilitating assembly of the core pack to the outer case. The plurality of ridges are separated on the upper case and the lower case, respectively, forming an uneven shape, preventing and suppressing deformation, distortion, and twisting of the outer case. Furthermore, the above configuration has the advantage that the inner groove along the joint promotes smooth diffusion and discharge of ejected material, enlarging the diffusion area and improving the safety of the battery pack.

[0018] In addition to any of the above configurations, a battery pack according to another embodiment of the present disclosure further includes a protective sheet between the ridge and the surface of the core pack, so that the ridge can support the core pack via the protective sheet.

[0019] To meet vibration resistance and impact resistance requirements, battery packs often use cushioning material (protective sheet) between the exterior case and the core pack. While pre-compressing the cushioning material is advantageous in terms of strength, pre-compressing the cushioning material presents a challenge in that it makes it difficult to insert and attach the core pack to the exterior case during battery pack assembly. The battery pack described above has the advantage of being able to stably hold the core pack with a simple configuration while facilitating assembly of the core pack to the exterior case. The configuration also has the advantage of improving the rigidity of the battery pack. By providing a protective sheet between the ridges and the surface of the core pack, the protective sheet's effectiveness can be enhanced. This is because, in addition to the uneven shape of the recesses and ridges, the interposed protective sheet allows the area of ​​the ridges facing the core pack to be appropriately set and adjusted, and a pre-compressed protective sheet can be interposed. This is because the protective sheet can protect the core pack, improving the battery pack's earthquake resistance, impact resistance, and drop resistance, and the elasticity of the protective sheet, in addition to the uneven shape of the concave and convex stripes, can prevent damage to the core pack due to vibration, impact, etc. The above configuration is particularly useful for battery packs for electric bicycles and electric motorcycles, which require high vibration resistance to withstand severe vibrations during driving, and portable battery packs, which are subject to strong impacts if dropped during transportation and therefore require high rigidity, drop resistance, and impact resistance.

[0020] Embodiments of the present disclosure will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concepts of the present disclosure, and the present disclosure is not limited to the following. Furthermore, this specification does not in any way specify the components set forth in the claims to be those of the embodiments. The dimensions, materials, shapes, relative positions, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure, and are merely illustrative examples, unless otherwise specified. The size and positional relationships of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate components that are identical or of the same quality, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present disclosure may be configured with the same components, such that multiple elements are served by a single component, or conversely, the functions of a single component may be shared by multiple components.

[0021] The battery pack of the present disclosure can be used as a driving power source for mobile devices such as electric motorcycles, electric carts, electric scooters, and assisted bicycles, as a power source for portable electrical devices such as radios, electric cleaners, and power tools, as a backup power source for servers in stationary power storage applications, as a power supply device for home, office, or factory use, and as a driving power source for vehicles such as hybrid cars and electric automobiles. Hereinafter, a battery pack 100 used as a driving power source for an electric motorcycle will be described as one embodiment of the present disclosure. [Embodiment 1]

[0022] 1 to 12 show a battery pack 100 according to a first embodiment of the present disclosure. FIGS. 1 and 2 are schematic perspective views of the battery pack 100, FIG. 3 is an exploded perspective view showing the core pack 2 attached to the exterior case 10, FIG. 4 is a schematic perspective view of the core pack 2, protective sheet 70, and inner bag 60, FIG. 5 is a schematic exploded perspective view of the core pack 2, FIG. 6 is a schematic perspective view of the upper case 10A viewed from below, FIG. 7 is a schematic perspective view of the lower case 10B viewed from above, FIG. 8 is a schematic view showing the inner surface 20b of the longitudinal side surface 22 of the battery pack, FIG. 9 is a schematic view showing the inner surface 20b of the end surface 22a of the battery pack, FIG. 10 is a horizontal cross-sectional view of the battery pack 100 taken along line X-X, FIG. 11 is an enlarged cross-sectional view of a main portion of the screw boss 50, and FIG. 12 is a vertical cross-sectional perspective view of the battery pack 100 taken along line XII-XII. The battery pack 100 shown in these figures includes an exterior case 10 and a core pack 2. (Core Pack 2)

[0023] The battery pack 100 shown in Figures 1 to 3 houses a core pack 2 inside an exterior case 10. The core pack 2 has multiple battery cells 1. The core pack 2 is composed of a battery block 7 having a battery holder 5 that houses the multiple battery cells 1, and a circuit board 3, and is also called a battery module. As shown in Figure 4, the core pack 2 can be housed inside an inner bag 60 to provide a waterproof structure.

[0024] The battery block 7 has a battery holder 5 that arranges, houses, and holds multiple battery cells 1 in a predetermined position and orientation. The battery holder 5 is divided into, for example, multiple sub-holders 5a that sandwich the battery cells 1. In the example shown in Figure 5, the battery holder 5 houses and holds multiple cylindrical battery cells 1 in a vertical orientation. The multiple battery cells 1 are connected in series or parallel via lead plates 4 or the like. The number of series connections or parallel connections can be set as desired according to the required specifications. In the example shown in Figure 5, the core pack 2 uses 112 battery cells 1, forming a 14-in-series x 8-in-parallel configuration. However, this configuration is not limiting and any number or arrangement can be used as appropriate. The core pack 2 may also be composed of multiple battery blocks 7, with each battery block 7 housing multiple battery cells 1.

[0025] The battery holder 5 has multiple storage cylinders 6 for individually storing battery cells 1. In the example shown in Figure 5, the battery holder 5 is divided into two parts, an upper part and an lower part, and the two storage cylinders 6 sandwich the battery cells 1 from above and below. The number of sections of the battery holder 5 is not limited to two; it can be three or more. The battery holder 5 can be made of a resin with excellent insulating properties, such as polycarbonate. Lead plates 4 are arranged on the battery holder 5 and equipped with guides for positioning the lead plates 4. The lead plates 4 are made of metal plates with excellent conductivity, such as aluminum or nickel, and connect the electrodes on the end faces of the battery cells 1 to connect multiple battery cells 1 in series or parallel. Electrode windows are partially opened to expose the electrodes of the lead plates 4. An insulating plate can be placed on the end face of the lead plate 4. A protective sheet 70 can also be used as the insulating plate. The insulating plate is formed to cover the entire surface of the lead plate 4. The insulating plate is made of a material with excellent insulating properties and fire resistance, such as mica.

[0026] The battery block 7 (battery cells 1) is connected to the circuit board 3 via lead plates 4. The circuit board 3 is equipped with a charge / discharge circuit that charges and discharges the battery cells 1, and a protection circuit that monitors the voltage and temperature of the battery cells 1 and cuts off the current in the event of an abnormality. The circuit board 3 is made of a glass epoxy board or similar material. A board holder for holding the circuit board 3 may also be provided. (Battery Cells 1)

[0027] The battery cells 1 may be secondary battery cells with cylindrical or rectangular outer shapes. In the example shown in FIG. 5 , cylindrical battery cells 1 are arranged vertically in a staggered pattern. The number and arrangement of the battery cells 1 are not limited to this example, and any number and arrangement may be used as appropriate. For example, the cylindrical battery cells 1 may be arranged in a matrix. Each battery cell 1 has positive and negative electrodes. The positive and negative electrodes are provided on one or both end faces of the battery cell 1. The battery cells 1 may be any known or future-developed secondary battery, such as a lithium-ion secondary battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

[0028] The exterior can of the battery cell 1 is provided with a discharge valve on its discharge end surface. The discharge valve opens in response to an increase in the internal pressure of the exterior can, releasing gas and other ejected materials inside the exterior can to the outside. The discharge valve is provided on one of the cell end surfaces of the battery cell 1, for example, on the positive electrode side. A battery cell 1 equipped with a discharge valve can prevent the battery cell 1 from exploding by opening in the event of an abnormality. The discharge valve opens when the battery cell 1 experiences thermal runaway and the internal pressure exceeds a threshold. As a result, the ejected materials, including gas and ejected materials, ejected from the opening of the battery cell 1 into the exterior case 10 can reach abnormally high temperatures and pressures. This can cause the ejected materials to concentrate in specific locations, such as corners, causing thermal damage to the exterior case 10 and even breaking through, resulting in the ejected materials being ejected to the outside of the exterior case 10. However, the battery pack 100 of the present disclosure smoothly diffuses the ejected materials, expanding the diffusion area and reducing and attenuating the thermal and kinetic energy of the ejected materials, thereby preventing and avoiding such situations. As the energy density of batteries increases, it is becoming increasingly important to improve the safety of battery packs at low cost. (External case 10)

[0029] The outer case 10 houses the core pack 2. The outer shape of the outer case 10 can be any shape that has an internal space 13 for housing the core pack 2 inside. In the example shown in Figures 1 to 3, the outer case 10 has a box-like appearance that extends in one direction, and has a handle 12 on one end surface 22a. The outer case 10 is preferably made of a material with excellent insulating properties, such as a resin such as high-density polyethylene, polypropylene, polyimide, polycarbonate, or PC-ABS alloy, but may also be made of a metal material such as aluminum or its alloy.

[0030] The outer case 10 can be closed by joining and connecting multiple separate components, such as a main body and a lid, vertically or horizontally, with connecting members. The outer case 10 shown in FIG. 3 has two separate upper and lower cases 10A and 10B. For example, the upper and lower cases 10A and 10B in FIG. 3 have overlapping portions at the opening edges, and are connected by threaded bosses 50 through which screws 51 are threaded. The outer case 10 shown in FIG. 3 has multiple screw bosses 50 on a wall surface 20 with grooves 30, and the upper and lower cases 10A and 10B are screwed together to securely connect the two cases. The outer case 10 includes an internal space 13 for accommodating a core pack 2, and the internal space 13 is enclosed by the wall surface 20. The present disclosure does not specify the structure, configuration, or connection method of the outer case 10; any structure or shape of the outer case 10 is possible in which a core pack 2 can be placed, stored, or inserted therein to form a closed structure.

[0031] The outer case 10 (upper case 10A and lower case 10B) has wall surfaces 20 that cover the core pack 2 on the outside of the core pack 2. The outer case 10 in Figures 1 to 3 has a plurality of pairs of opposing wall surfaces 20. The wall surfaces 20 in the figures have side surfaces 22 (including end surfaces 22a), a top surface 23, and a bottom surface 24, and the side surfaces 22 have side surfaces 22 in the longitudinal direction and side surfaces 22 in the lateral direction (end surfaces 22a).

[0032] The exterior case 10 is provided with one or more exhaust ports 14 for discharging ejected material to the outside in the event of an abnormality in which the gas exhaust valve of the battery cell 1 opens and high-pressure gas or the like is discharged. The exhaust ports 14 are sufficient as long as they are capable of discharging ejected material to the outside, and their shape, size, number, and placement are not specified. However, for example, the shape of the exhaust ports 14 can be rectangular, polygonal (e.g., octagonal, hexagonal, or square), circular, track-shaped, or elliptical. The exhaust port 14 shown in Figure 2 is located on the end surface 22a of the upper case 10A of the exterior case 10 opposite the handle 12. In Figure 2, a water drainage opening located on the end surface 22a of the exterior case 10 serves as the exhaust port 14 for gas discharged from the battery cell 1. (Recessed grooves 30)

[0033] The exterior case 10 has a recessed rib 30 on the outer surface 20a of the wall surface 20, which is recessed inward of the wall surface 20. The recessed rib 30 is recessed inward relative to the non-recessed first surface 21 (outer surface 20a), and has an outer concave shape formed on the outer surface 20a side of the wall surface 20. The recessed rib 30 has a bottom 31 and a recessed rib frame 32. The bottom 31 is a bottom recessed inward relative to the first surface 21. The recessed rib frame 32 is connected to the outer edge of the bottom 31 and connects the bottom 31 to the first surface 21. The recessed rib 30 has a height difference in the recessing direction (the first recessed rib 30X in FIG. 2 is in the Z direction), and the depth (D) of the recessed rib 30 is the height difference (distance) between the first surface 21 and the bottom 31. 2 has a flat surface portion 31a, and the wide flat surface portion 31a (e.g., the first groove 30X) is less likely to collect dust and is easy to clean. The flat surface portion 31a forms the flat surface portion 41a of the protrusion 40 on the inner surface 20b side of the wall surface 20.

[0034] The grooves 30 on the outer surface 20a of the wall surface 20 form ridges 40 on the inner surface 20b of the wall surface 20. The grooves 30 and ridges 40 are integrated on the outer surface 20a and inner surface 20b of the wall surface 20, forming unevenness, steps, and grooves on the wall surface 20. The depth (D) of the grooves 30 and the height (H) of the ridges 40 are both greater than the thickness of the wall surface 20, and the grooves 30 are recessed inward from the outer surface 20a (first surface 21) of the wall surface 20, while the ridges 40 protrude inward from the inner surface 20b (first surface 21) of the wall surface 20. A configuration in which the grooves 30 on the outer surface 20a form the ridges 40 on the inner surface 20b allows the thickness of the wall surface 20 to be substantially the same, reducing material costs without increasing the thickness. The depth (D) of the grooves 30 and the height (H) of the ridges 40 in FIG. 12 are approximately the same. However, the depth (D) of the recessed ribs 30 and the height (H) of the protruding ribs 40 may be different in depth or height difference, for example, by making the wall surface 20 have a different shape or thickness. In this disclosure, the inside refers to the side closer to the core pack 2, i.e., the side closer to the internal space 13 of the outer case 10, and the outside refers to the side farther from the core pack 2, i.e., the outside of the outer case 10.

[0035] The exterior case 10 can have multiple recesses 30 on one or multiple wall surfaces 20. The exterior case 10 illustrated in Fig. 2 has four first recesses 30X (30X1 to 30X4) in the longitudinal center of the side surface 22 and four second recesses 30Y (30Y1 to 30Y4) at the end near the end surface 22a, each of which is separated and spaced apart. Furthermore, third recesses 30Z (30Z1, 30Z2) and fourth recesses 30W (30W1, 30W2) are provided on the end surface 22a. Each of the grooves 20 (first groove 30X, second groove 30Y, third groove 30Z, fourth groove 30W) on the outer surface 20a of the wall surface 20 forms a ridge 40 (first ridge 40X, second ridge 40Y, third ridge 40Z, fourth ridge 40W) described below on the inner surface 20b of the wall surface 20, and an inner groove portion 43 is formed between the ridges formed by adjacent grooves 30. Since the grooves 30 and the ridges 40 are in a one-sided relationship on the outer surface 20a side and the inner surface 20b side of the wall surface 20, the description of the ridge 40 on the inner surface 20b side corresponds to the groove 30 on the outer surface 20a side. (ridge 40)

[0036] The outer case 10 has a raised ridge 40 that protrudes inward on the inner surface 20b of the wall surface 20. The ridge 40 protrudes inward (toward the internal space 13) beyond the non-concave first surface 21 (inner surface 20b). The ridge 40 has an inner convex shape formed on the inner surface 20b of the wall surface 20 by the concave ridge 30. The outer case 10 has the ridge 40 that protrudes inward beyond the first surface 21, and the ridge 40 abuts against and holds the core pack 2. Furthermore, the unevenness, steps, and groove shape of the ridge 40 can improve rigidity. The ridge 40 does not protrude outward beyond the first surface 21, and without increasing the external size of the outer case 10, it can achieve features such as stable support for the core pack 2, easy assembly of the core pack 2, improved rigidity of the outer case 10, and improved safety of the battery pack 100.

[0037] The ridge 40 has a tip portion 41 and a ridge frame portion 42. The tip portion 41 is a peak or tip side that protrudes inward relative to the first surface 21. The ridge frame portion 42 is connected to the outer edge of the tip portion 41 and connects the tip portion 41 to the first surface 21. The ridge 40 has a height difference in the protruding direction (the first ridge 40X in FIG. 1 is the Z direction), and the height (H) of the ridge 40 is the height difference (distance) between the first surface 21 and the tip portion 41.

[0038] The tip portion 41 is shaped to match the shape of the core pack 2 it abuts, thereby holding and protecting the core pack 2. The tip portion 41 has a planar surface 41a that is entirely or partially flat. The planar surface 41a in FIGS. 8 and 9 is generally rectangular, with rounded corners 44. The planar surface 41a abuts the outer surface of the core pack 2 to provide stable support. The rounded shapes of the planar surface 41a and the rounded corners 44 reduce damage to the tip portion 41 caused by contact and rubbing against the core pack 2 due to vibration or impact, protect the core pack 2 with its elasticity, and improve vibration resistance and impact resistance. Furthermore, the uneven and stepped shape of the ridges 40 improves the rigidity of the outer case 10. For example, the planar surface 41a of the first ridge 40X is generally rectangular and elongated in the X direction, and the planar surface 41a of the second ridge 40Y is generally rectangular and elongated in the Y direction. The flat surface 41a can be formed in a shape other than a rectangle, for example, a polygon such as a triangle, a square, a pentagon, or a hexagon, a circle, an ellipse, an L-shape, a C-shape, or any other regular or irregular shape, and can be formed in a shape that matches the wall surface 20 of the core pack 2 and the outer case 10.

[0039] The ridges 40 can be positioned closer to the periphery than the center of the wall surface 20. The ridges 40 in Figures 8 and 9 are positioned closer to the upper edge 25 and lower edge 26 of the periphery than the center in the vertical direction (Y direction) on the side surface 22 and end surface 22a of the wall surface 20. The core pack 2 can be held by both the upper edge 25 of the upper case 10A and the lower edge 26 of the lower case 10B, as well as the ridges 40, improving the rigidity of the outer case 10. A portion of the flat portion 41a can be connected to the edge of the outer periphery of the highly rigid wall surface 20 of the outer case 10. For example, the flat portion 41a of the first ridge 40X in Figures 8 and 9 has an upper edge 45a that serves as the upper edge 25 connecting the upper surface 23 and side surface 22 of the upper case 10A, and left and right vertical edges 45c and a lower edge 45b that connect to the ridge frame portion 42. This configuration allows the area of ​​the flat portion 41a to be expanded to the outer peripheral edge of the wall surface 20, and the highly rigid flat portion 41a connected to the upper edge 25 and three sides of the protruding frame portion 42 can stably hold the core pack 2.

[0040] The convex strip frame portion 42 is provided on all or part of the periphery of the tip portion 41. The convex strip frame portion 42 in FIGS. 8 and 9 is connected to the tip portion 41 at three sides, excluding the upper side 45a or the lower side 45b. For example, the first convex strip 40X1 connects the left and right vertical sides 45c and the lower side 45b of the periphery of the tip portion 41 to the convex strip frame portion 42. It is also possible to have a convex strip frame portion 42 connected to the entire periphery of the tip portion 41, thereby providing a stepped shape around the entire periphery of the convex strip 40. As shown in FIGS. 11 and 12, the convex strip frame portion 42 has a first connecting portion 42a on the inside, which is one end side, connected to the tip portion 41, and a second connecting portion 42b on the outside, which is the other end side, connected to the first surface 21. The tip portion 41 is connected to the ridge frame portion 42 via the first connecting portion 42a, and the ridge frame portion 42 is connected to the first surface 21 via the second connecting portion 42b. The stepped shape of the ridges 40 improves the rigidity of the outer case 10 with a small height difference, and the ridge frame portion 42 acts as a beam connecting the first surface 21 and the tip portion 41, and connects the tip portion 41 (bottom portion 31) and the first surface 21 in an oppositely bent shape (S-shape) at a close position via the first connecting portion 42a and the second connecting portion 42b, efficiently improving the rigidity of the outer case 10 with a simple configuration.

[0041] All or part of the ridge frame portion 42 can be oriented perpendicular (vertical surface) or inclined (inclined surface) relative to the tip portion 41 and / or the first surface 21. The ridge frame portion 42 can be oriented perpendicular to the tip portion 41 and the first surface 21 to increase the area of ​​the tip portion 41 (flat portion 41a). As shown in FIG. 12 , the ridge frame portion 42 can be oriented in an inclined manner, with the inwardly protruding ridges 40 tapering toward the tip portion 41, i.e., with the first connecting portion 42a being smaller in size and shape than the second connecting portion 42b. This not only facilitates assembly of the core pack 2, but also improves elasticity and absorbs drops and impacts. The inclination angle of the ridge frame portion 42 can be determined for each side, and can also be partially different inclination angles, or have a curved surface. For example, the upper edge 45a or the lower edge 45b can be made to have a gentler inclination than the vertical edge 45c, and the left and right vertical edges 45c can be made to have a gentler or steeper inclination than the upper edge 45a or the lower edge 45b, or a nearly vertical surface, thereby adjusting the rigidity and elasticity of the ridge 40 and the wall surface 20. The ridge frame portion 42 of the first ridge 40X1 can be made to have a gentler inclination on the lower edge 45b side of the long side than the vertical edge 45c, thereby improving elasticity. The ridge frame portion 42 of the first ridge 40X3 has an inclined surface on the upper edge 45a side of the long side, which facilitates insertion and assembly of the core pack 2. The same applies to the lower edge 45b of the long side of the ridge frame portion 42 of the first ridge 40X1. Furthermore, the first connecting portion 42a and / or the second connecting portion 42b have a curved, rounded shape, which, like the inclined surfaces and rounded corners 44 of the protruding frame portion 42, can improve the elasticity of the wall surface 20, thereby improving the retention of the core pack 2 and improving vibration resistance and impact resistance. It also facilitates the insertion and assembly of the core pack 2. The tip portion 41 and / or the protruding frame portion 42 may further have unevenness, an inclined surface, a step, or the like. For example, the flat portion 41a may have a tapered surface, an inclined surface, or a curved surface on the peripheral edge on the insertion side of the core pack 2 that gradually decreases in width in the insertion direction of the core pack 2, which can contribute to stable support of the core pack 2, ease of assembly, and protection.

[0042] The outer case 10 has multiple ridges 40, which can be of the same or different shapes and sizes. The contact area, position, and holding pressure of the ridges 40 that contact the core pack 2 can be adjusted by adjusting the arrangement, shape, size, number, and height difference of the ridges 40. This allows the outer case 10 to stably support the core pack 2, improves the rigidity of the outer case 10, and enables the optimal shape and design to be achieved according to the core pack 2, thereby improving the strength performance (vibration resistance and impact resistance) and installation and processability of the battery pack 100. By arranging the multiple ridges 40 separately, the core pack 2 can be efficiently and stably held. Furthermore, the inner surface 20b of the wall surface 20 has a non-holding portion that does not contact the outer surface of the core pack 2, making it easier to attach and insert the core pack 2 into the outer case 10, and the stepped shape reinforces the outer case 10, efficiently improving the rigidity of the outer case 10. The separately arranged ridges 40 have screw bosses 50 between adjacent ridges 40 to connect and close the outer case 10. Furthermore, inner grooves 43 are provided between the ridges 40, and these grooves serve as gas channels 43a for diffusing ejected material, improving the safety of the battery pack 100. The inner grooves 43 reduce the thickness of the wall surface 20, reducing material costs, while improving the rigidity of the outer case 10 through their uneven, stepped shape. The outer case 10 can also increase the thickness of the wall surface 20 by filling the grooves between adjacent ridges 40 without providing inner grooves 43. The ridges 40 can have shapes that differ partially from other portions and from other ridges 40. For example, by providing a second ridge 40Y with a relatively narrow width (w2) at the end, slightly extending inward from the tips 41 of the other ridges 40, rotation and positional changes of the core pack 2 can be suppressed or prevented. When a load is applied to the end, the second convex strip 40Y, which has a narrow width (w2), deforms first, and then the force can be received by all the tip portions 41 (flat portions 41a) of the other convex strips 40, such as the first convex strip 40X.

[0043] The outer case 10 can be provided with a plurality of ridges 40 on both or one of a pair of opposing wall surfaces 20. This configuration, in which a plurality of ridges 40 are provided on both sides of a pair of opposing wall surfaces 20, allows the ridges 40 to hold the core pack 2 from both sides, and the ridges 40 on both sides can expand the range of adjustment for the area, arrangement, shape, etc. of the contact surface for the core pack 2, making it easier to assemble the core pack 2 to the outer case 10 and improving the rigidity of the wall surfaces 20 on both sides.

[0044] The exterior case 10 shown in Figure 8 has multiple ridges 40 on the side surface 22 in the longitudinal direction of the wall surface 20, with four first ridges 40X (40X1 to 40X4) located in the central portion of the longitudinal direction of the side surface 22 and four second ridges 40Y (40Y1 to 40Y4) located at separate distances at the end portion near the end surface 22a. The multiple ridges 40 in Figure 8 have the same shape for the first ridges 40X and the same shape for the second ridges 40Y, but the first ridges 40X and the second ridges 40Y have different shapes. The width (w2) of the second ridges 40Y located at the end portions is smaller than the width (w1) of the first ridges 40X located in the central portion. The second ridge 40Y, which has a relatively narrow width (w2) at its end, has a tip portion 41 (flat portion 41a) extending in the vertical direction (Y direction), improving rigidity and effectively preventing and suppressing deformation and twisting of the outer case 10, as well as suppressing rotation, movement, and change in orientation of the core pack 2. The narrow ridge 40 can maintain the position and orientation of the core pack 2 even if the outer case 10 deforms. The first ridge 40X, which has a relatively wide width (w1), has a tip portion 41 (flat portion 41a) extending in the horizontal direction (X direction), and the tip portion 41 (flat portion 41a) can hold the core pack 2 over a wide contact area by utilizing the length of the longitudinal side surface 22. Combining both the relatively wide and narrow ridges 40 not only holds the core pack 2, but also makes it easier to attach and insert the core pack 2 into the outer case 10, and further efficiently improves the rigidity of the outer case 10. The width (w) of the ridge 40 can be constant, or can be gradually increasing or decreasing.

[0045] The outer case 10 may have multiple ridges 40 on one or more wall surfaces 20. In the outer case 10 shown in Figures 8 and 9, in addition to the longitudinal side surfaces 22, the end surfaces 22a have third ridges 40Z (40Z1, 40Z2) and fourth ridges 40W (40W1, 40W2). The end surfaces 22a have a relatively wide third ridge 40Z (w3) located in the center and a fourth ridge 40W that is relatively narrower (w4) than the third ridge 40Z. The descriptions of the wide first ridge 40X and narrow second ridge 40Y on the side surfaces 22 apply to these ridges. Together with the longitudinal side surfaces 22, these ridges facilitate retention of the core pack 2 and ease of attachment and insertion of the core pack 2 into the outer case 10, improving the rigidity of the outer case 10.

[0046] The multiple ridges 40 and ridge frame portions 42 in Figures 8 and 9 are arranged in a substantially parallel position. The flat portions 41a extending in a parallel position in the horizontal direction (X direction) and the vertical direction (Y direction) can stably hold the core pack 2 over a wide contact area, and the parallel steps and uneven shapes can improve rigidity. By arranging the multiple ridge frame portions 42 in a substantially vertical position in the intersecting direction, rigidity in each extension direction can be improved. In Figure 8, from the left side of the upper case 10A, the flat surfaces 41a of the second convex rib 40Y1, the first convex rib 40X1, the first convex rib 40X2, and the second convex rib 40Y2 are arranged in the longitudinal direction (X direction), and from the left side of the lower case 10B, the flat surfaces 41a of the second convex rib 40Y3, the first convex rib 40X3, the first convex rib 40X4, and the second convex rib 40Y4 are arranged in the longitudinal direction (X direction) at positions facing each convex rib 40 of the upper case 10A. The convex stripe frame portion 42 around the periphery of the first convex stripe 40X1 extends in the X direction (toward the lower edge 45b of the first convex stripe 40X1) and in the Y direction (left and right vertical edges 45c). The convex stripe frame portions 42 of the adjacent first convex stripes 40X2 to 40X4 and second convex stripes 40Y1 to 40Y4 also extend in the X direction (toward the lower edge 45b or upper edge 45a) and in the Y direction (toward the left and right vertical edges 45c) to provide reinforcement in each direction. In Figures 8 and 9, the multiple convex stripe frame portions 42 are arranged so as to extend longitudinally from one end to the other and also so as to extend transversely from the upper edge 25 to the lower edge 26. In Figures 8 and 9, the lower edges 45b of the multiple convex stripe frame portions 42 of the upper case 10A and the upper edges 45a of the multiple convex stripe frame portions 42 of the lower case 10B are arranged substantially on the same line. The left and right vertical sides 45c of the upper case 10A and the lower case 10B are also arranged substantially on the same line.

[0047] The multiple ridges 40 in Figures 8 and 9 are arranged in one row on each of the upper case 10A and the lower case 10B, and in two rows on each of the side surface 22 and the end surface 22a, with the roughly rectangular (quadrilateral) planar portion 41a having a vertical side 45c extending in the Y direction and an upper side 45a and a lower side 45b extending in the X direction. The exterior case 10 shown in the figures has a ridge 40 (e.g., a first ridge 40X) having a planar portion 41a whose horizontal side (e.g., upper side 45a) is longer than the vertical side 45c, and a ridge 40 (e.g., a first ridge 40Y) having a planar portion 41a whose vertical side 45c is longer than the horizontal side (e.g., upper side 45a), which are arranged adjacent to each other. The multiple ridges 40 can be arranged symmetrically with respect to a line in the up-down direction (Y direction) and / or left-right direction (X direction). Furthermore, the multiple ridges 40 may have portions arranged in line symmetry and / or point symmetry, and in any case, the ridges 40 can abut and hold the core pack 2 in a balanced manner, such as symmetrically or diagonally.

[0048] 8 and 9, the protruding strips 40 are arranged separately on the upper case 10A and the lower case 10B, and further, the protruding strips 40 are arranged so as to avoid the joint 11 between the upper case 10A and the lower case 10B. In the above configuration, for example, in FIG. 8, the tip 41 of each of the plurality of protruding strips 40 arranged spaced apart from each other, such as four locations of the first protruding strips 40X1, 40X2 and the second protruding strips 40Y1, 40Y2 on the upper case 10A and four locations of the first protruding strips 40X3, 40X4 and the second protruding strips 40Y3, 40Y4 on the lower case 10B, is in contact with the core pack 2 to efficiently and stably hold it. In addition, the spaced apart arrangement makes it possible to adjust the contact area, arrangement, and non-contact portions to facilitate insertion and attachment of the core pack 2, and the uneven shape of each of the protruding strips can improve the rigidity of the outer case 10. 8, the convex ribs 40 can be arranged symmetrically with respect to the joint 11, and the tip portion 41 (flat portion 41a) extending in the longitudinal direction (X direction) parallel to the joint 11 can be provided over a wide area. Furthermore, an inner groove 43 forming a gas flow path 43a can be provided along the joint 11, and the gas flow path 43a can communicate with a gas discharge gap (gas flow path 43a) from one end to the other end. For example, as shown in FIGS. 8 and 9, the inner groove 43 can be provided in the center of the longitudinal side surface 22 and end surface 22a in the up-down direction (Y direction) so as to extend longitudinally from one end to the other end of the side surface 22 and end surface 22a, respectively, allowing the ejected material to be diffused smoothly and the diffusion area of ​​the ejected material to be increased.

[0049] The multiple, separated ridges 40 can form inner grooves 43 sandwiched between adjacent ridges 40. The inner grooves 43 are groove-shaped gaps that open inward on the inner surface 20b of the outer case 10 between adjacent ridges 40. The inner grooves 43 form gaps between the core pack 2 and the inner surface 20b of the outer case 10 and can be used as gas flow paths 43a for the outflow and diffusion of ejected material, such as gas emitted from the battery cells 1 in the event of an abnormality. Depending on the direction of extension (vertical, horizontal, or diagonal) and the orientation of the inner grooves 43, the inner grooves 43 can smoothly flow in, out, guide, direct, and diffuse the ejected material, preventing high-temperature, high-pressure ejected material from concentrating and pooling in specific locations, such as the corners of the outer case 10. For example, as shown in FIG. 8 , when an inner groove 43 is disposed on the longitudinal side surface 22 of the exterior case 10, the gas flow passages 43a extending in the vertical direction (Y direction) can diffuse the ejected material from the discharge end surface of the battery cell 1 disposed above or below in the vertical direction (Y direction). The gas flow passages 43a extending in the horizontal direction (X direction) can diffuse the ejected material in the horizontal direction (X direction) regardless of which battery cell 1 the ejected material is from. The exterior case 10 can be provided with a ridge 40 (inner groove 43) on a wall surface 20 other than the surface facing the discharge end surface of the battery cell 1, for example, on the side surface 22 (end surface 22a) facing the side surface of the battery cell 1, thereby making the diffusion of the ejected material by the gas flow passages 43a more efficient and effective. The same applies when an inner groove 43 (gas flow passage 43a) is formed on the end surface 22a of the exterior case 10, as shown in FIG. 9 . The gas emitted from the battery cells 1 and diffused through the gas flow paths 43a is discharged to the outside of the exterior case 10, for example, from the exhaust ports 14 on the end surface 22a of the exterior case 10. The gas emitted from the battery cells 1 is also discharged to the outside of the exterior case 10 from gaps formed at the joining edge of the upper case 10A and the lower case 10B of the exterior case 10 due to an increase in pressure inside the exterior case 10 caused by the gas emitted from the battery cells 1.

[0050] The gas flow path 43a is connected to the end space 1a formed between the inner surface 20b of the exterior case 10 and the discharge end face of the battery cell 1, allowing for smooth diffusion of the ejected material, expanding the diffusion area of ​​the ejected material, and gaining time to gradually reduce the thermal energy and kinetic energy of the high-temperature, high-pressure ejected material, thereby improving the safety of the battery pack 100. The end space 1a formed between the inner surface 20b of the exterior case 10 and the discharge end face of the battery cell 1 is provided in the upper and lower spaces facing both the upper and lower end faces of the battery cell 1, and the gas flow path 43a communicates with the upper and lower spaces. This configuration allows for the ejected material ejected from the discharge end face to be diffused to the exterior case 10 on the opposite side of the discharge end face, expanding the diffusion area. Furthermore, in a battery pack 100 in which the discharge end faces of multiple battery cells 1 are arranged on both the upper and lower end faces, this configuration can accommodate ejected material ejected from either discharge end face. The inner groove 43 can be used as a ventilation and cooling flow path during normal operation. The upper case 10A and the lower case 10B can have uneven portions on the inner surface 20b facing the discharge end face. The uneven portions have a tip portion on the side close to the discharge end face and a bottom portion on the side away from the discharge end face, and the tip portion and bottom portion of the uneven portion are arranged with a difference in height in the vertical direction relative to the discharge end face, and a simple configuration such as a checkerboard or honeycomb shape can be used to reduce costs and reduce the risk of damage to the exterior case 10 in the event of an abnormality.

[0051] The multiple inner grooves 43 can be arranged in an intersecting orientation, such as a cross or X shape. The inner grooves 43 in Figures 8, 9, and 12 have a first inner groove 43H extending horizontally (the longitudinal side surface 22 extends in the X direction, and the end surface 22a extends in the Z direction) between the respective ridges 40 of the upper case 10A and the lower case 10B, and a second inner groove 43V extending vertically. The first inner groove 43H and the second inner groove 43V intersect (are perpendicular to each other) at an intersection 43b. The width (s1) of the first inner groove 43H at the intersection 43b is set larger than the width (s2) of the second inner groove 43V excluding the screw boss 50, allowing the ejected material to be smoothly dispersed in the vertical and horizontal directions.

[0052] In one wall surface 20 where an inner groove 43 is provided, the inner groove 43 can be provided extending from one outer periphery to the other outer periphery on the opposite side, allowing for smooth diffusion of ejected material via the gas flow paths 43a. In the longitudinal side surface 22 shown in FIG. 8 , the first inner groove 43H extends from the left edge connecting with the left end face 22a (one outer periphery) to the left edge connecting with the right end face 22a (the other outer periphery). The second inner groove 43V extends from the upper edge 25 (one outer periphery) to the lower edge 26 (the other outer periphery). The first inner groove 43H and / or the second inner groove 43V on the end face 22a in FIG. 9 can be provided in a similar manner.

[0053] The outer case 10 in FIGS. 10 and 11 has screw bosses 50 between adjacent ridges 40 for securing screws 51 that join the upper case 10A and the lower case 10B. The screw bosses 50 can be positioned in the inner grooves 43 between adjacent ridges 40. The screw bosses 50 protrude inward from the inner surface 20b of the wall surface 20. This configuration increases the thickness of the wall surface 20 (inner grooves 43) without increasing the external size of the outer case 10. Furthermore, the unevenness and stepped shape formed by the screw bosses 50 and the ridges 40 on both sides improves strength and rigidity. This allows the upper case 10A and the lower case 10B to be securely fastened together with screws without misalignment. By spacing the screw bosses 50 apart, the reliability of the connection between the upper case 10A and the lower case 10B and the rigidity of the outer case 10 can be more efficiently improved.

[0054] As shown in Fig. 11 , the height (h) of the screw boss 50, i.e., the height (h) by which the screw boss 50 protrudes inward, is set lower than the height (H) of the ridge 40. The inner tip of this screw boss 50 does not protrude inward beyond the tips 41 of the ridges 40 on both sides, preventing the screw boss 50 from contacting the core pack 2 (inner bag 60, protective sheet 70). The screw boss 50 in Fig. 11 has its inner tip (height h) positioned lower than the tip (height H) of the tip 41 of the ridge 40 by the height difference (s), separating the screw boss 50 from the core pack 2 and preventing contact. This configuration prevents the inner tip of the screw boss 50 from protruding inward beyond the tips 41 of the ridges 40 on both sides, preventing the screw boss 50 from directly contacting the core pack 2, protective sheet 70, inner bag 60, etc., preventing external impacts and vibrations from being directly applied through the screw boss 50, preventing damage from contact or friction, and allowing the screw boss 50 to relieve stress generated by the screws 51, etc., improving the vibration resistance and impact resistance of the battery pack 100. Furthermore, the screw boss 50 stably holds the core pack 2 via the ridges 40, without interfering with the assembly of the core pack 2 to the outer case 10, achieving both. (Inner bag 60)

[0055] The inner bag 60 covers the outer periphery of the battery holder 5 inside the outer case 10. The inner bag 60 is waterproof, and protects the battery cells 1 housed in the outer case 10 from water. For this reason, the inner bag 60 is made of a waterproof material.

[0056] The inner bag 60 is made of a flexible material. In the example shown in FIG. 4, the inner bag 60 is shown box-shaped, but this shape is not limited to this and may be an irregular shape such as a bag. For such an inner bag 60, a resin with excellent heat resistance, flame retardancy, flexibility, and abrasion resistance, such as polyolefin resin or polyethylene resin, e.g., PET resin, may be used. Heat-shrinkable tubing that shrinks when heated may also be used. Furthermore, the inner bag 60 may be equipped with a check valve that exhausts internal gas while preventing moisture from passing through from the outside. (Protective sheet 70)

[0057] The protective sheet 70 is interposed between the ridges 40 and the core pack 2 and protects the core pack 2 as a cushioning material. Part or all of one or more protective sheets 70 are arranged between the core pack 2 and the ridges 40, so that the ridges 40 abut against the protective sheets 70, thereby stably supporting the core pack 2 via the protective sheets 70. The protective sheet 70 reduces the repulsive force, making it easier to insert the core pack 2 and improving ease of assembly. The protective sheet 70 can cover the surface of the inner bag 60 and can be attached or adhered to the surface.

[0058] The protective sheet 70 is made of an elastic and flexible material. By interposing the elastic protective sheet 70 between the outer surface of the core pack 2 (inner bag 60) and the inner surface 20b of the hard outer case 10, the inner bag 60 and the core pack 2 stored in the inner bag 60 can be protected. Specifically, the inner bag 60 and the core pack 2 can be protected from external forces such as impact and vibration. Furthermore, the flexible inner bag 60 can be prevented from being torn by friction due to impact, vibration, etc. The protective sheet 70 is made of an insulating material, such as a heat-resistant or flame-retardant rubber sheet or foam. Preferably, a CR (chloroprene rubber)-based rubber sheet can be used.

[0059] The protective sheet 70 that protects the surfaces of the core pack 2 and the inner bag 60 covers all or part of the outer surface 2A of the core pack 2 and can be provided on one or more outer surfaces 2A of the core pack 2. The protective sheet 70 can be limited to the portion that abuts the ridge 40, and can be provided not only on the surface facing the wall surface 20 on which the ridge 40 is provided, but also on the non-facing surface. Multiple protective sheets 70 can be spaced apart according to the shape and arrangement of the ridge 40. Two protective sheets 70 shown in Figures 3 and 4 are arranged on the outer surface of the core pack 2 that faces the wall surface 20 on which the ridge 40 is provided (side surface 22 and end surface 22a in the figures). The protective sheet 70 in Figures 3 and 4 has a first protective sheet 71 and a second protective sheet 72 that are spaced apart. The first protective sheet 71 continuously covers the side surfaces 2a (longitudinal and lateral sides 2a) of the core pack 2 and the top surface 2b adjacent to the side surfaces 2a, while the second protective sheet 72 continuously covers the side surfaces 2a (longitudinal and lateral sides 2a) of the core pack 2 and the bottom surface 2c adjacent to the side surfaces 2a. The protective sheet 70 provided on multiple side surfaces 2a provides broad protection for the surface of the core pack 2 and other components, making it easy to position the core pack 2 in a predetermined location and preventing misalignment. The protective sheet 70 can also have other functions, such as covering the discharge end surface where the discharge valve is located. By using the protective sheet 70, which covers the battery holder 5 to improve impact resistance, to cover the discharge end surface where the discharge valve is located, high-temperature, high-pressure gas is prevented from immediately escaping from the battery pack 100 even if it were to be discharged from the discharge valve of one of the battery cells 1. This prevents the flame from igniting the gas and leaking directly outside the battery pack 100. Furthermore, the protective sheet 70 can contribute to improving the insulation and waterproof properties of the core pack 2.

[0060] For example, battery packs 100 for electric bicycles and electric motorcycles require high vibration resistance to withstand the intense vibrations experienced during operation. Portable battery packs 100 are subject to strong impacts if dropped during transport, and therefore require high rigidity, drop resistance, and impact resistance. To meet these requirements, a cushioning material (protective sheet 70) may be provided between the exterior case 10 and the core pack 2. While pre-compressing the cushioning material is advantageous in terms of strength, pre-compressed cushioning material presents a problem in that it makes it difficult to insert and attach the core pack 2 to the exterior case 10 during assembly of the battery pack 100. The exterior case 10 of the present disclosure has a simple configuration with multiple ridges 40 on the wall surface 20, which allows for stable support of the core pack 2 while facilitating assembly of the core pack 2 to the exterior case 10 and further improving the rigidity, earthquake resistance, and impact resistance of the battery pack 100. Furthermore, by providing the protective sheet 70 between the ridges 40 and the outer surface of the core pack 2, in addition to the uneven shape of the recesses 30 and the ridges 40, the ridges 40 abutting the interposed protective sheet 70 can determine the holding pressure and contact area on the core pack 2 within appropriate ranges, thereby achieving both stable holding of the core pack 2 and easy assembly of the core pack 2 to the outer case 10. For example, while the protective sheet 70 has a predetermined thickness and shape, the contact area and holding pressure can be adjusted by the size, shape, arrangement, number, etc. of the ridges 40. The ridges 40 can eliminate or alleviate the difficulty of assembling the core pack 2 to the outer case 10 due to the presence of the pre-compressed protective sheet 70. Furthermore, the protective sheet 70 can protect the core pack 2, and the presence of the pre-compressed protective sheet 70 can further improve the earthquake resistance, impact resistance, and drop resistance of the battery pack 100. The elasticity of the protective sheet 70, in addition to the uneven shape of the concave and convex ribs 30 and 40, reduces the impact on the core pack 2 of vibrations and shocks of the battery pack 100, preventing damage. The effectiveness and usefulness of the protective sheet 70 are particularly evident in battery packs 100 for electric bicycles and electric motorcycles, portable battery packs 100, and heavy battery packs 100, where vibration resistance, impact resistance, and high rigidity are increasingly important.

[0061] In the above example, the battery pack 100 is used as a power source for an electric motorcycle. However, the present disclosure is not limited to this application. The battery pack can also be attached to an electric device to be driven and used for other purposes, such as supplying power to the electric device. Examples of electric devices include mobile objects such as electric vehicles and electric carts, as well as portable electric devices. In such electric devices, when the remaining capacity of the battery pack becomes low or the battery pack deteriorates over time, the battery pack can be replaced to continue using the electric device. However, the present disclosure is not limited to replaceable battery packs that primarily house battery cells 1, but can also be applied to battery packs in which the battery cells 1 are housed within the housing of the electric device. In the present disclosure, the battery pack 100 is defined as a battery pack in which the battery cells 1 are housed within an exterior case 10, and also includes battery packs in which the driving battery cells 1 are built into the housing of the electric device itself. In other words, the present disclosure is not limited to replaceable battery packs, but can also be applied to electric devices that house battery cells.

[0062] The battery pack according to the present invention can be suitably used as a driving power source for mobile objects such as electric scooters, electric carts and assisted bicycles, as a power source for radios, and as a power source for portable electrical equipment such as electric cleaners and power tools, as a backup power source for servers and the like, and as a stationary power storage device for home, office and factory use, etc.

[0063] DESCRIPTION OF SYMBOLS 100...Battery pack 1...Battery cell 1a...End surface space 2...Core pack 2A...Outer surface 2a...Side surface 2b...Top surface 2c...Bottom surface 3...Circuit board 4...Lead plate 5...Battery holder 5a...Sub-holder 6...Storage cylinder 7...Battery block 10...External case 10A...Upper case 10B...Lower case 11...Joint 12...Handle 13...Internal space 14...Discharge port 20...Wall surface 20a...Outer surface 20b...Inner surface 21...First surface 22...Side surface 22a...End surface 23...Top surface 24...Bottom surface 25...Top edge 26...Bottom edge 30...Concave strips 30X, 30X1 to 30X4...First concave strips 30Y, 30Y1 to 30Y4...Second concave strips 30Z, 30Z1, 30Z2...Third concave groove 30W, 30W1, 30W2...Fourth concave groove 31...Bottom 31a...Flat portion 32...Concave groove frame portion 40...Convex groove 40X, 40X1 to 40X4...First convex groove 40Y, 40Y1 to 40Y4...Second convex groove 40Z, 40Z1, 40Z2...Third convex groove 40W, 40W1, 40W2...Fourth convex groove 41...Tip portion 41a...Flat portion 42...Convex groove frame portion 42a...First connecting portion 42b...Second connecting portion 43...Inner groove portion 43H...First inner groove portion 43V...Second inner groove portion 43a...Gas flow path 43b...Intersection portion 44...Corner portion 45a...Upper side 45b...Lower side 45c...Vertical side 50...Screw boss 51...Screw 60...Inner bag 70...Protection sheet 71...First protection sheet 72...Second protection sheet

Claims

1. A battery pack comprising: a core pack containing a plurality of battery cells; and an exterior case that houses the core pack in an internal space, wherein the exterior case has a plurality of recesses on the outer surface of the wall, and the plurality of recesses form a plurality of ridges that protrude into the internal space, and the ridges are configured to support the core pack.

2. A battery pack as claimed in claim 1, wherein the plurality of ridges include ridges provided at the centre and at the ends of the wall surface, and the width (w) of the ridges at the ends is smaller than that of the ridges at the centre.

3. A battery pack as claimed in claim 1, wherein the exterior case is formed by joining an upper case and a lower case, the exterior case is provided with screw bosses for fixing screws joining the upper case and the lower case, and the screw bosses are provided between adjacent ridges.

4. A battery pack according to claim 3, wherein the height (h) of the screw boss is lower than the height (H) of the ridge.

5. A battery pack according to claim 1, wherein the plurality of ridges are arranged separately, and the exterior case has an inner groove portion between adjacent ridges on the inner surface of the wall.

6. A battery pack according to claim 5, wherein a gas flow path is formed in the inner groove portion, and the gas flow path is in communication with an end surface space formed between the inner surface of the exterior case and the discharge end surface of the battery cell.

7. A battery pack according to claim 5, wherein the exterior case has a plurality of the inner grooves arranged at intersecting positions.

8. A battery pack as claimed in claim 1, wherein the exterior case has an upper case and a lower case joined to the upper case, and the plurality of protrusions are formed separately on the upper case and the lower case, avoiding the joint between the upper case and the lower case.

9. A battery pack according to any one of claims 1 to 8, further comprising a protective sheet between the ridge and the surface of the core pack, wherein the ridge supports the core pack via the protective sheet.

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