Battery pack

Abstract

A battery pack (100) has an elastic body (20) provided on a part of each inner surface (12a) of a pair of lid parts (12). The pair of lid parts (12) are respectively fixed to each end surface of a battery block (2) housed in a housing space of a case body (11). A gap (GP) is formed between the pair of lid parts (12) and an end edge (11a) of each opening end in the case body (11). The lid parts (12) include a flat lid body (13) and a wall part (14) protruding from an inner surface of the lid body (13). The elastic body (20) is disposed so as to contact a surface of a wall part (14) facing an inner surface of the case body (44), and has an inclined surface (21) that widens toward an inner surface of the lid part (12). A part of the inclined surface (21) enters the gap (GP), and a corner part (19) positioned between the end edge (11a) of an opening end in the case body (11) and an inner surface (11b) of the case body (44) contacts the inclined surface (21).

Description

Battery pack

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

[0002] Battery packs are used in which multiple rechargeable secondary battery cells, such as lithium-ion secondary batteries, are connected in series or parallel and housed in an outer case to power a device (see, for example, Patent Document 1). Such battery packs use an outer case 1110, as shown in the exploded perspective view of FIG. 11 . The outer case shown in this figure is composed of a cylindrical case body 1111 with openings on both end faces to form an internal storage space, and a pair of lids 1112 that close each end face. A battery block 1102 holding multiple secondary battery cells is inserted into the storage space of the case body 1111. The battery block 1102 is inserted end-on from the case body 1111, and each end face is closed by a lid 1112. Each lid 1112 is screwed into an end-face screw hole 1108 opened in each end face of the case body 1111 using an end-face screw 1140.

[0003] Meanwhile, the bottom surface of the case body may be provided with bottom screw holes for fixing the battery block inside the storage space. When the battery block 1102 is inserted into the storage space of the case body 1111, the battery block 1102 is screwed in with bottom screws 1143 that are fastened to bottom screw holes 1109 of the case body 1111. In a battery pack 1100 with this structure, the battery block 1102 inside the case body 1111 is directly screwed in with the case body 1111, so the battery block 1102 can be stably fixed to the exterior case 1110.

[0004] However, depending on the specifications of the battery pack, such a configuration may not be possible. For example, if end screw holes are to be formed in the case body, the case body must be made thick. If the case body is made of metal to provide strength, increasing the thickness increases the weight and costs. On the other hand, to screw the bottom of the battery block to the case body, it is necessary to drill bottom screw holes in the bottom of the case body, but this configuration makes it difficult to waterproof the exterior case. For this reason, it may not be possible to screw the case body and the battery block directly. Therefore, a configuration in which the lid is directly fixed to the battery block without drilling end screw holes or bottom screw holes in the case body is considered.

[0005] As an example of such a configuration, consider a configuration in which block screw holes 1207 are opened in each end face of battery block 1202 to be inserted into case body 1211 of exterior case 1210, and lid 1212 is screwed in with end screws 1240, as shown in the exploded perspective view of Figure 12. In this configuration, each end face of case body 1211 and lid 1212 are not directly fixed. Furthermore, due to manufacturing tolerances of case body 1211 and battery block 1202, gaps will occur at the joint interface between case body 1211 and lid 1212, as shown in the cross-sectional view of Figure 13.

[0006] As a result, as shown by the arrow in Figure 13, the position of the case body 1211 is shifted by the amount of the gap between the case body 1211 and the lid portion 1212, which can hinder positioning when setting the battery pack in its designated position in the device to be driven, resulting in reduced ease of installation.

[0007] Furthermore, as shown in Figure 14, the case body 1211 moves by the gap between it and the lid 1212. Therefore, when the battery pack is used in an environment exposed to vibration or dropped and external stress is applied, contact may occur at the joint interface between the case body 1211 and the lid 1212, potentially resulting in damage. Depending on the application and standards of the battery pack, it may be required to pass reliability and durability tests such as drop tests and vibration tests. In particular, when the case body is made of metal to improve the rigidity of the exterior case and the lid is made of resin to improve the insulation of connectors provided on the lid, the difference in hardness between the metal case body and the resin lid may result in damage or cracking of the lid.

[0008] Patent No. 6049288

[0009] An object of the present disclosure is to provide a battery pack that can stably fix an outer case, a lid, and a battery block. Another object is to provide a battery pack that can accommodate component tolerances and has improved reliability against external forces. Note that the description of these objects and objects of the present disclosure does not preclude the existence of other objects and objects. Furthermore, it is not necessary for one embodiment of the present disclosure to solve all of these objects. Furthermore, other objects can be extracted from the description of the specification, drawings, and claims of the present disclosure.

[0010] A battery pack according to one aspect of the present disclosure includes: a battery block that holds a plurality of secondary battery cells; a case body that has a storage space, a first end surface and a second end surface that are each open, a first opening edge and a second opening edge; a first lid portion that covers the first opening edge of the case body; and a second lid portion that covers the second opening edge of the case body; and a first elastic body that is provided to abut against an inner surface of the first lid portion, wherein the battery block is stored in the storage space of the case body, the first lid portion is fixed to the first end surface of the battery block, and the second lid portion is The first cover portion is fixed to the second end surface of the battery block, and a first gap is formed between the first cover portion and the case body, and the first cover portion includes a flat first cover body and a first wall portion protruding from the inner surface of the first cover body, and the first elastic body is arranged to abut against the surface of the first wall portion facing the inner surface of the case body, and has a first inclined surface that widens toward the inner surface of the first cover portion, and a portion of the first inclined surface fits into the first gap, and a first corner portion located between the edge of the first opening end of the case body and the inner surface of the case body abuts against the first inclined surface.

[0011] According to a battery pack according to one embodiment of the present disclosure, while the battery block and the lid portion are fixed, a situation in which the main body case rattles between the lid portions on both sides due to a gap that occurs between the case body and the lid portion can be avoided by abutting the corners of the edge of the case body with an elastic body.

[0012] 1 is a perspective view showing a battery pack according to Embodiment 1. FIG. 1 is an exploded perspective view of the battery pack of FIG. 1. FIG. 1 is a cross-sectional view taken along line III-III of FIG. 1. FIG. 3 is an enlarged cross-sectional view of a main portion showing the dashed line portion of FIG. 3. FIG. 2 is an enlarged exploded perspective view showing the lid portion and elastic body of FIG. 2. FIG. 5 is an exploded perspective view of the lid portion and elastic body of FIG. 5 as seen from the rear side. FIG. 6 is a perspective view showing a state in which an elastic body is connected to the lid portion of FIG. 6. FIG. 7 is an exploded perspective view of a battery block. FIG. 8 is a schematic cross-sectional view showing a state in which an elastic body is omitted from the battery pack. FIG. 9 is a schematic cross-sectional view showing a state in which an elastic body is added to FIG. 9. FIG. 10 is an exploded perspective view of a battery pack according to Comparative Example 1. FIG. 11 is an exploded perspective view of a battery pack according to Comparative Example 2. FIG. 12 is a schematic cross-sectional view of the battery pack of FIG. 12. FIG. 13 is a schematic cross-sectional view showing the battery pack of FIG. 13 with the case main body moved to the left, and FIG. 13 is a schematic cross-sectional view showing the battery pack of FIG. 13 with the case main body moved to the right. FIG. 4 is an enlarged cross-sectional view showing an example in which the gap is NG in FIG. 4. FIG. 4 is an enlarged cross-sectional view showing an example in which the gap is maximum in FIG. 4.

[0013] The embodiments of the present disclosure may be specified by the following configurations and features.

[0014] In a battery pack according to another aspect of the present disclosure, in the above aspect, the first elastic body extends so that the first inclined surface widens in a region where the first lid and the edge of the first opening end of the case body overlap, as viewed from the lid. With this configuration, by bringing the corners of the case body into contact with the inclined surface, it is possible to prevent rattling of the case body.

[0015] In another aspect of the battery pack according to the present disclosure, in any of the above aspects, the first elastic body includes a flange that protrudes toward the inner surface of the case body. With this configuration, the battery pack can be sealed liquid-tight with the flange, achieving a waterproof structure. Furthermore, the elastic body that achieves the waterproof structure can be used to prevent rattle of the case body, so that a rattle-preventing structure can be achieved using existing components without adding any new components.

[0016] In a battery pack according to another aspect of the present disclosure, in any of the above aspects, the first lid body has a recess between the first wall portion and the periphery of the first lid body, and the first elastic body has a protrusion that is inserted into the recess of the first lid body. With this configuration, the lid and the elastic body can be positioned and joined by inserting the protrusion into the recess. In particular, by providing the recess and the protrusion in the direction that secures the lid to the battery block, the lid body can push the elastic body in the securing direction, allowing for stable attachment.

[0017] In a battery pack according to a further aspect of the present disclosure, in any of the above aspects, the first elastic body is integrally formed with the first wall portion by two-color molding. With this configuration, the elastic body can be easily fixed to the lid portion.

[0018] In a battery pack according to still another aspect of the present disclosure, in any of the above aspects, the first corner of the first opening end of the case body is chamfered. With this configuration, the corner that comes into contact with the elastic body is made obtuse, increasing the contact area and more stably preventing rattling of the case body.

[0019] In a battery pack according to still another aspect of the present disclosure, in any of the above aspects, the pair of lids are fixed to the respective end faces of the battery block by screwing. With this configuration, the lids and the battery block can be easily fixed together.

[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 objects such as power-assisted bicycles, electric carts, and electric scooters, 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 unit for home, office, or factory use, and as a driving power source for vehicles such as hybrid cars and electric automobiles. A battery pack used as a driving power source for a power-assisted bicycle will be described below as one embodiment of the present invention.

[0022] [Embodiment 1] A battery pack 100 according to Embodiment 1 of the present disclosure is shown in Figures 1 to 10. In these figures, Figure 1 is a perspective view showing the battery pack 100 according to Embodiment 1, Figure 2 is an exploded perspective view of the battery pack 100 of Figure 1, Figure 3 is a cross-sectional view taken along line III-III of Figure 1, Figure 4 is an enlarged cross-sectional view of a main portion showing the dashed line portion of Figure 3, Figure 5 is an enlarged exploded perspective view showing the lid portion 12 and the elastic body 20 of Figure 2, Figure 6 is an exploded perspective view of the lid portion 12 and the elastic body 20 of Figure 5 as seen from the rear side, Figure 7 is a perspective view showing the state in which the elastic body 20 is connected to the lid portion 12 of Figure 6, Figure 8 is an exploded perspective view of the battery block 2, Figure 9 is a schematic cross-sectional view showing the battery pack 100 without the elastic body 20, and Figure 10 is a schematic cross-sectional view showing the state in which the elastic body 20 is added to the state of Figure 9. The battery pack 100 shown in these figures includes a battery block 2, an outer case 10, and an elastic body 20. The battery block 2 is made up of a plurality of secondary battery cells 1.

[0023] (External Case 10) The external case 10 has an outer shape that extends in one direction, as shown in Figures 1 to 3. Here, the external shape of the external case 10 is formed into a chamfered prismatic shape, but various cross-sectional areas and shapes, such as a polygonal shape or a cylindrical shape, can also be used.

[0024] (Case body 11) In the example shown in Figures 2 and 3, the exterior case 10 includes a case body 11 and a pair of lids 12. The case body 11 is formed in a cylindrical shape with both ends open, and the interior serves as a storage space. Each of the open ends at both ends is square-shaped. However, as described above, the case body 11 can also be cylindrical, in which case the open ends are circular.

[0025] The case body 11 is made of a material with excellent strength and heat dissipation properties, such as a metal member such as aluminum or its alloy, while the exterior case may be made of a material with excellent insulation properties, such as a resin such as polycarbonate or PC-ABS alloy.

[0026] (Lid portion 12) The pair of lid portions 12 are formed to a size and shape that allows them to cover the respective open ends of the case body 11. In the examples shown in Figures 2, 3, and 4, each lid portion 12 is formed so that the inner surface 12a of the lid portion 12, i.e., the side facing the open end of the case body 11, has a footprint that is approximately equal to the size of the end face of the case body 11. Furthermore, an outer surface 12b of the lid portion 12 that is exposed to the outside is provided with a connector or the like for electrical connection to the outside as needed.

[0027] Each lid portion 12 has a wall portion 14 formed on its inner surface 12a. Specifically, the lid portion 12 includes a lid main body 13 and a wall portion 14 extending from the inner surface 12a of the lid main body 13. As shown in FIG. 5, the lid main body 13 is formed in a flat plate shape. The wall portion 14 is provided on the inner surface 12a of the lid main body 13. In the example shown in FIG. 6, the wall portion 14 extends from the lid main body 13 in a position that protrudes toward the open end of the case body 11. This wall portion 14 is preferably formed integrally with the lid main body 13. In the example shown in FIG. 7, the wall portion 14 is formed in a frame shape that is slightly smaller than the outer diameter of the square-shaped lid main body 13. An elastic body 20 is disposed around the wall portion 14. As shown in FIGS. 5 and 6, the lid portion 12 is fixed to the case body 11 with the elastic body 20 covering the periphery of the wall portion 14.

[0028] Each lid 12 is fixed to each end face of the battery block 2 housed in the storage space of the case body 11. The lid 12 and battery block 2 are fixed together by screwing, rivets, welding, or the like. In the examples shown in FIGS. 2 , 6 , and 7 , screws 40 are used for screwing. For this reason, the lid body 13 has threaded holes 15 at its four corners for threading the screws 40, as shown in FIG. 2 and other figures. Preferably, as shown in the schematic cross-sectional view of FIG. 9 , a step 16 is formed around each screw hole 15 on the outer surface 12b of the lid body 13, so that the head 41 of the screw 40 fits within the step 16 when screwed, preventing the head 41 of the screw 40 from protruding from the outer surface 12b of the lid body 13. Furthermore, as shown in FIGS. 6 and 7 , cylindrical bosses 17 are formed around each screw hole 15 on the inner surface 12a of the lid body 13. Preferably, the boss 17 and the wall portion 14 are connected by a rib 18 to improve the strength of the lid portion 12.

[0029] (Gap GP) When each cover 12 is secured to each end face of the battery block 2, a gap GP is formed between the cover 12 and the edge of the case body 11, as shown in Figure 9. For ease of explanation, the left-side gap GP1 and the right-side gap GP2 are shown to be approximately equal, but in reality they are not necessarily equal, and narrowing one gap will increase the other. These gaps are absorbed by the elastic body 20, as shown in Figure 10 (details will be described later).

[0030] (Battery Block 2) The battery block 2, also known as a battery module or core pack, houses multiple rechargeable battery cells 1. The battery block may also be composed of multiple sub-blocks, each housing multiple rechargeable battery cells. In the examples shown in Figures 2 and 8, multiple cylindrical rechargeable battery cells 1 are housed and held horizontally in the battery holder 5. The battery holder 5 can be divided into multiple parts.

[0031] (Lead Plates 7) The battery block 2 is composed of a battery holder 5, rechargeable battery cells 1, and lead plates 7. The lead plates 7 are arranged on the side of the battery holder 5. The lead plates 7 connect the electrodes on the end faces of the rechargeable battery cells 1 to connect multiple rechargeable battery cells 1 together. The lead plates 7 are made of highly conductive metal plates such as aluminum, nickel, or copper. Multiple rechargeable battery cells 1 are connected in series or parallel via the lead plates 7. The number of series connections or parallel connections can be set as desired according to the required specifications. In the example shown in Figure 2, a total of 42 rechargeable battery cells 1 are used in the entire battery block 2, forming a 14 series x 3 parallel configuration, but this configuration is not limited to this.

[0032] The battery block 2 is connected to a circuit board via lead plates 7 and bus bars. The circuit board is equipped with a charge / discharge circuit that charges and discharges the rechargeable battery cells 1, and a protection circuit that monitors the voltage and temperature of the rechargeable battery cells 1 and cuts off the current in the event of an abnormality. The circuit board is made of a glass epoxy board or the like. The battery block 2 may also have a board holder 4 attached to it as a member for holding the circuit board.

[0033] The battery holder 5 has multiple storage cylinders 6 that individually store the rechargeable battery cells 1. For example, as shown in Figure 8, each battery holder 5 is divided into two, left and right, and the two storage cylinders 6 hold the rechargeable battery cells 1 from the left and right. Such battery holders 5 can be made of resin such as polycarbonate, which has excellent insulating properties.

[0034] (Secondary battery cells 1) The multiple secondary battery cells 1 are arranged in a battery holder 5 so that the end faces of each secondary battery cell 1 are flush with one another. Each secondary battery cell 1 can be a cylindrical or rectangular secondary battery cell. In the example shown in FIG. 8 , the cylindrical secondary battery cells 1 are horizontally placed and arranged in a staggered pattern. Note that the number and arrangement of the secondary battery cells are not limited to this example, and any number and arrangement can be used as appropriate. For example, cylindrical secondary battery cells may be arranged in a matrix.

[0035] Each secondary battery cell 1 has a positive and a negative electrode. Preferably, one of the positive and negative electrodes is provided on one end face of the secondary battery cell 1, and the other is provided on the other end face. In the example shown in FIG. 2 , the negative electrode is provided on the bottom side of the exterior can of the secondary battery cell 1, and the exterior can serves as the negative electrode. Such secondary battery cells 1 can be any known secondary battery, such as a lithium-ion secondary battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

[0036] (Elastic Body 20) As shown in FIG. 9 , when each lid portion 12 is fixed to each end face of the battery block 2, gaps GP1 and GP2 are formed between the lid portion 12 (lid portion main body 13) and the edge 11a of the case main body 11. To fill these gaps GP1 and GP2, an elastic body 20 is provided on each inner surface 12a of each lid portion 12, as shown in FIG. 10 . Each elastic body 20 is positioned so as to abut against the surface of the wall portion 14 that faces the inner surface 11b of the case main body 11 (see FIG. 9 ). In other words, the elastic body 20 is formed in an annular shape so as to cover the periphery of the wall portion 14. In the examples shown in FIGS. 5 and 6 , the elastic body 20 is formed in a square shape, but the elastic body 20 may also be formed in a polygonal or annular shape, etc., depending on the shape of the wall portion 14.

[0037] (Inclined Surface 21) Each elastic body 20 forms an inclined surface 21 that widens toward the inner surface 12a of the lid portion 12. As shown in FIG. 4 , the inclined surface 21 partially fits into the gap GP. As a result, a corner 19 between the edge and the inner surface of the open end of the case body 11 abuts against part of the inclined surface 21. With this configuration, the battery block 2 and the lid portion 12 are fixed together, and a situation in which the main case rattles between the lid portions 12 on both sides due to the gap GP that occurs between the case body 11 and the lid portion 12 is prevented by abutting the corner 19 of the edge of the case body 11 against the elastic body 20.

[0038] A configuration for stably holding the main case will now be described with reference to FIGS. 11 to 14 . Consider a battery pack 1100 according to Comparative Example 1, as shown in the exploded perspective view of FIG. 11 , in which a battery block 1102 is inserted into an outer case 1110 and closed with a lid 1112. The outer case 1110 is composed of a cylindrical case body 1111 with openings on both end faces to form a storage space inside, and a pair of lids 1112 that close each end face. The battery block 1102, which holds multiple secondary battery cells 1, is inserted into the storage space of the case body 1111. With the battery block 1102 inserted end-first into the case body 1111, each end face is closed with a lid 1112. Each lid 1112 is screwed into an end screw hole 1108 opened in each end face of the case body 1111 using an end screw 1140. 11 , bottom screw holes 1109 for fixing battery block 1102 inside the storage space are provided on the bottom surface of case body 1111. This battery block 1102 is inserted into the storage space of case body 1111 and fixed by screwing with bottom screws 1143 that are fastened to bottom screw holes 1109 of case body 1111. In battery pack 1100 with this structure, battery block 1102 inside case body 1111 is directly screwed into case body 1111, so battery block 1102 can be stably fixed to exterior case 1110.

[0039] However, depending on the specifications of the battery pack, such bottom screws may not be usable. For example, if end screw holes are to be formed in the case body, the case body must be made thick. In particular, if the case body is made of metal to ensure strength, increasing the thickness of the case body increases the weight and costs. On the other hand, in order to screw the bottom of the battery block 2 or the like into the case body, bottom screw holes must be drilled in the bottom of the case body, but this configuration makes it difficult to waterproof the exterior case. For these reasons, it may not be possible to screw the case body and the battery block directly together. For this reason, it is possible to design the case body without drilling end screw holes or bottom screw holes, and to directly fasten the lid to the battery block 2.

[0040] As an example of such a configuration, a battery pack 1200 according to Comparative Example 2 is shown in the exploded perspective view of Figure 12. In this battery pack 1200, block screw holes 1207 are opened in each end face of a battery block 1202 that is inserted into a case body 1211, and a lid portion 1212 is screwed into the battery block 1202 with end screws 1240. In this configuration, each end face of the case body 1211 and the lid portion 1212 are not directly fixed to each other. Furthermore, due to manufacturing tolerances of the case body 1211 and the battery block 2, a gap GP inevitably occurs at the joint interface between the case body 1211 and the lid portion 1212, as shown in the cross-sectional view of Figure 13.

[0041] As a result, as shown by the arrow in Figure 13, a positional shift of the case body 1211 occurs by the amount of the gap GP between the case body 1211 and the lid portion 12, which can hinder positioning when setting the battery pack 1200 in a fixed position on the device to be driven, resulting in reduced ease of installation.

[0042] Furthermore, as shown in FIG. 14 , the case body 1211 moves by a gap GP between the case body 1211 and the lid portion 1212. Therefore, when the battery pack 1200 is used in an environment exposed to vibration or dropped, and external stress is applied, contact may occur at the joint interface between the case body 1211 and the lid portion 1212, potentially resulting in breakage. Depending on the application and standards of the battery pack, reliability and durability tests such as drop tests and vibration tests may be required. In particular, when the case body is made of metal to improve the rigidity of the exterior case, and the lid portion is made of resin to improve the insulation of connectors provided on the lid, the difference in hardness between the metal case body and the resin lid may result in breakage or cracking of the lid.

[0043] In contrast, in the battery pack 100 according to this embodiment, the elastic body 20 is disposed as shown in Fig. 10 to suppress rattle caused by the gap GP as shown in Fig. 9. Specifically, as shown in Fig. 15, an elastic body 20 is disposed on the outer side of each wall portion 14, and a portion of an inclined surface 21 formed on the elastic body 20 and flaring toward the inner surface 12a of the lid portion 12 is arranged to fit into the gap GP between the lid body 13 and the opening edge of the case body 11. With this arrangement, a corner 19 between the opening edge and the inner side of the case body 11 abuts against a portion of the inclined surface 21. As a result, the case body 11 is supported from at least one side by the inclined surface 21 that fits into the gap GP between the left and right lid portions 12 and the case body 11.

[0044] Here, the size of the gap GP varies from one part to another depending on component tolerances, etc. Therefore, the length of the inclined surface 21 is designed so that the corner 19 can abut against the inclined surface 21 to close the gap GP even at the maximum conceivable gap GP. In other words, as shown in Figure 16, the dimensions of the inclined surface 21 are designed to avoid a situation where the corner 19 does not abut against the inclined surface 21 and the gap GP cannot be closed. The angle of the inclined surface 21 with respect to the wall 14 is preferably 35° to 55°, and more preferably around 45°.

[0045] As shown in Fig. 17, the inclined surface 21 of the elastic body 20 elastically deforms when the corner 19 comes into contact with it, supporting the case body 11 from at least one of the left and right sides. This achieves a battery pack 100 with improved reliability against external forces, regardless of manufacturing tolerances of the case body 11, the lid 12, etc. In other words, the case body is prevented from wobbling left and right between the pair of lids as shown in Fig. 14, preventing damage to the contact surfaces between the case body and the lid, thereby improving the reliability of the exterior case.

[0046] When a cover portion 12 is fixed to each end face on both sides of the battery block 2 as in the battery pack 100 of this embodiment and an elastic body 20 is placed on each of the pair of left and right cover portions 12, the elastic body 20 on each of the pair of left and right cover portions 12 can prevent the case body 11 from rattling left and right between the pair of cover portions 12, which is advantageous in enhancing the effect of suppressing rattling left and right.

[0047] When viewed from the lid 12, the elastic body 20 has an inclined surface 21 that extends in a fan-like manner in the region where the lid 12 and the edge of the open end of the case body 11 overlap. This configuration inevitably causes the corners 19 of the case body 11 to come into contact with the inclined surface 21, making it possible to prevent the case body 11 from rattling.

[0048] The elastic body 20 is made of a material having elasticity, such as a thermoplastic elastomer or synthetic rubber.

[0049] The elastic body 20 may also be formed integrally with the wall portion 14 by two-color molding. Two-color molding allows the wall portion 14 and the elastic body 20, which are made of different materials, to be molded alternately in one cycle, making it possible to create a single molded product from two types of resin, and thus makes it easy to obtain the lid portion 12 in which the elastic body 20 is fixed to the wall portion 14 in advance.

[0050] (Flange 22) The elastic body 20 also has a flange 22 that protrudes from the inner surface 12a of the case body 11. As shown in FIG. 15 and other figures, the height of the flange 22 is designed to be slightly greater than the distance between the elastic body and the inner surface of the case body 11. This allows the leading edge of the flange 22 to abut against the inner surface of the case and elastically deform, creating a liquid-tight seal between the periphery of the wall 14 and the case body 11, thereby achieving a waterproof structure for the battery pack 100. Furthermore, the elastic body 20 that achieves the waterproof structure can be used to prevent rattle of the case body 11, allowing for a rattle-preventing structure to be achieved using existing components without adding new components. In other words, by changing the shape of the gasket used to achieve the waterproof structure, rattle prevention functionality for the case body can be added in addition to the waterproof structure. By using the same components, reliability can be improved at a low cost and with a simple configuration.

[0051] 15, the flange 22 is formed in two layers to improve waterproofing, but the flange 22 may be formed in one layer or three layers depending on the required waterproofing performance.

[0052] A recess 13a may be formed on the inner surface 12a of the lid body 13. As shown in Figures 6, 15, etc., the recess 13a is formed in a ring shape along the periphery of the inner surface 12a of the lid body 13 between the portion where the wall portion 14 is provided and the periphery.

[0053] (Protrusion 23) On the other hand, the elastic body 20 has a protrusion 23 formed on the surface facing the inner surface 12a that is inserted into the recess 13a, as shown in Figure 4. With this configuration, the lid portion 12 and the elastic body 20 can be positioned and joined by inserting the protrusion 23 into the recess 13a. Furthermore, by providing the recess 13a and the protrusion 23 in the direction that secures or presses the lid portion 12 to the battery block 2, the lid main body 13 can push the elastic body 20 in the securing direction, ensuring stable attachment.

[0054] The case body 11 also has chamfered corners 19 at the open end. This configuration makes the corners 19 that come into contact with the elastic body 20 obtuse, increasing the surface pressure at the contact point and more stably preventing rattling of the case body 11.

[0055] In the above example, the battery pack is used as a power source for an electric-assisted bicycle. However, the present disclosure is not limited to this. 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 secondary battery cells, but can also be applied to battery packs in which secondary battery cells are housed within the housing of the electric device. In the present disclosure, a battery pack is defined as a battery pack that houses secondary battery cells in a case, and also includes battery packs in which secondary battery cells for driving the electric device 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 secondary battery cells.

[0056] The battery pack according to the present invention can be suitably used as a driving power source for mobile objects such as electric carts and electric scooters in addition to power-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.

[0057] REFERENCE SIGNS LIST 100 Battery pack 1 Rechargeable battery cell 2 Battery block 5 Battery holder 6 Storage cylinder 7 Lead plate 10 Outer case 11 Case body 11a Edge 11b Inner surface 12 Lid portion 12a Inner surface 12b Outer surface 13 Lid body 13a Recess 14 Wall 15 Screw hole 16 Step 17 Boss 18 Rib 19 Corner 20 Elastic body 21 Inclined surface 22 Flange 23 Convex portion 40 Screw 41 Head 1100, 1200 Battery pack 1102, 1202 Battery block 1108 End screw hole 1109 Bottom screw hole 1110, 1210 Outer case 1111, 1211 Case body 1112, 1212 Lid 1140 End screw 1143 Bottom screw 1240 End screw GP Gap GP1 Left side gap GP2 Right side gap

Claims

1. A battery block that holds a plurality of secondary battery cells; a case body having a storage space, a first open end and a second open end, each of which is opened at a first end face and a second end face, a first lid portion that covers the first open end of the case body, and a second lid portion that covers the second open end of the case body; and a first elastic body provided on an inner surface of the first lid portion, wherein the battery block is stored in the storage space of the case body, the first lid portion is fixed to the first end face of the battery block, and the second lid portion is fixed to the second end face of the battery block, a first gap is formed between the first lid portion and the case body, the first lid portion includes: a flat first lid body; and a first wall portion that protrudes from the inner surface of the first lid body, the first elastic body is disposed so as to abut against a surface of the first wall portion that faces the inner surface of the case body, and has a first inclined surface that widens toward the inner surface of the first lid portion, A battery pack in which a portion of the first inclined surface fits into the first gap, and a first corner of the case body located between an edge of the first opening end of the case body and the inner surface of the case body abuts against the first inclined surface.

2. A battery pack as described in claim 1, wherein the first elastic body extends so that the first inclined surface widens in the area where the first cover portion and the edge of the first opening end of the case body overlap when viewed from the cover portion.

3. A battery pack as claimed in claim 1, wherein said first elastic body further includes a flange portion protruding towards said inner surface of said case body.

4. A battery pack as described in claim 1, wherein the first lid body has a recess between the first wall portion and the periphery of the first lid body, and the first elastic body has a protrusion that is inserted into the recess of the first lid body.

5. A battery pack according to any one of claims 1 to 4, wherein the first elastic body is integrally formed with the first wall portion by two-color molding.

6. A battery pack according to any one of claims 1 to 4, wherein the first corner of the first opening end of the case body is chamfered.

7. A battery pack as claimed in any one of claims 1 to 4, wherein the first lid portion is fixed to the first end face of the battery block by screwing, and the second lid portion is fixed to the second end face of the battery block by screwing.

8. A battery pack as claimed in any one of claims 1 to 4, further comprising a second elastic body provided on the inner surface of the second lid portion, a second gap being formed between the second lid portion and the case body, the second lid portion including a flat second lid body and a second wall portion protruding from the inner surface of the second lid body, the second elastic body being arranged to abut against a surface of the second wall portion facing the inner surface of the case body, and having a second inclined surface that widens towards the inner surface of the second lid portion, a portion of the second inclined surface fitting into the second gap, and a second corner of the case body located between the edge of the second opening end of the case body and the inner surface of the case body abutting against the second inclined surface.