Battery pack

Abstract

Provided is a battery pack in which adhesion to a cylindrical battery cell is improved. The battery pack 100 comprises a battery case 1 provided with a plurality of accommodating sections 11 each accommodating one cylindrical battery cell 10, the accommodating sections 11 being arranged in a row in one direction, wherein: the accommodating sections 11 each have a wall section 12 which demarcates a space for accommodating the cylindrical battery cell 10; the wall sections 12, in a state before accommodating the cylindrical battery cell 10, each demarcate an elliptically cylindrical space; the wall sections 12 are each provided with a slit 13 which is parallel to the center axis C of the elliptically cylindrical space; the long-axis direction of the elliptically cylindrical space is the direction in which the accommodating sections 11 are arranged in the one direction, the short-axis direction is a direction perpendicular to the long-axis direction, and the depth direction is a direction which is perpendicular to the long-axis direction and to the short-axis direction and which is parallel to the center axis C of the elliptically cylindrical space; and the short-axis diameter L2, where the elliptically cylindrical space in each accommodating section 11 is the longest in the short-axis direction, is no greater than the diameter of the cylindrical battery cell 10.

Description

[Technical Field]

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

[0002] Patent Document 1 describes a battery holder that holds multiple cylindrical batteries in an aligned state, and has multiple cylindrical battery storage sections that respectively store each battery, with each battery storage section formed by a roughly cylindrical wall section that has spring properties that allow it to expand in diameter when a battery is inserted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-207569 Summary of the Invention [Problem to be solved by the invention]

[0004] It is technically known that cylindrical batteries have dimensional tolerances. For example, if the diameter of a cylindrical battery accommodated in a battery holder is within the maximum dimensional tolerance, the battery accommodating section will expand and deform, allowing the cylindrical battery to be properly accommodated in the battery accommodating section. However, if the diameter of a cylindrical battery accommodated in a battery holder is within the minimum dimensional tolerance, the battery accommodating section will not expand and deform, reducing the adhesion between the cylindrical battery and the battery accommodating section, potentially preventing the cylindrical battery from being properly accommodated in the battery holder.

[0005] Therefore, a primary object of the present disclosure is to provide a battery pack with improved adhesion to cylindrical battery cells. [Means for solving the problem]

[0006] The battery pack according to the present disclosure comprises: A battery pack including a battery case having a plurality of housing sections each housing a single cylindrical battery cell, the housing sections being arranged in a line in one direction, the housing portion has a wall portion that defines a space for housing the cylindrical battery cell; the wall portion defines an elliptical cylindrical space before the cylindrical battery cell is housed therein; a slit is provided in the wall portion parallel to the central axis of the elliptical cylindrical space, The direction in which the storage sections are lined up in one direction is the long axis direction of the elliptical cylindrical space, the direction perpendicular to the long axis direction is the short axis direction, the direction perpendicular to the long axis direction and the short axis direction and parallel to the central axis of the elliptical cylindrical space is the depth direction, and the longest short axis diameter in the short axis direction of the elliptical cylindrical space in the storage section is less than the diameter of the cylindrical battery cell. [Effects of the Invention]

[0007] The battery pack of the present disclosure can provide a battery pack with improved adhesion to cylindrical battery cells. Specifically, a wall defining an elliptically extending space has a slit parallel to the central axis of the elliptical cylindrical space, thereby improving adhesion between the wall and the outer circumferential surface of the cylindrical battery cells. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view schematically illustrating a first embodiment of a battery pack according to the present disclosure. [Figure 2] FIG. 2 is a front view of the battery case in the first embodiment as viewed from the axial direction. [Figure 3] FIG. 10 is a front view of a battery case according to a modification of the first embodiment, viewed from the axial direction. [Figure 4] FIG. 10 is a perspective view schematically illustrating a second embodiment of a battery pack according to the present disclosure. [Figure 5] FIG. 10 is a front view of a battery case according to a second embodiment, viewed from the axial direction. [Figure 6]FIG. 10 is a perspective view schematically illustrating a third embodiment of a battery pack according to the present disclosure. [Figure 7] FIG. 11 is a front view of a battery case according to a third embodiment, viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0009] A battery pack according to an embodiment of the present disclosure will be described in more detail below. While the description will be made with reference to drawings as needed, the various elements in the drawings are merely shown schematically and for illustrative purposes to facilitate understanding of the present disclosure, and the appearance and dimensional ratios may differ from those of the actual product.

[0010] Various numerical ranges mentioned in this specification are intended to include the lower and upper limit numerical values ​​themselves, unless otherwise specified, such as "less than" or "more than / greater than." For example, a numerical range such as 1 to 10 can be interpreted as including the lower limit of "1" and the upper limit of "10." Furthermore, terms such as "about" and "approximately" mean that the range may include a variation of a few percent, for example, ±10%.

[0011] As used herein, the term "plan view" refers to the state when an object (e.g., a battery pack) is placed and viewed from directly above in the thickness (height) direction, and is synonymous with a plan view. For example, the term "plan view" refers to the state when viewed along the negative direction in the "short axis direction" shown in FIG. 1. Unless otherwise specified, the term "side view" refers to the state when an object (e.g., a battery pack) is placed and viewed from the side perpendicular to the thickness (height) direction, and is synonymous with a side view. For example, the term "side view" refers to the state when viewed along the negative direction (or positive direction) in the "long axis direction" shown in FIG. 1. Unless otherwise specified, the term "front view" refers to the state when an object (e.g., a battery pack) is placed and viewed from the front perpendicular to the thickness (height) direction, and is synonymous with a front view. For example, the term "front view" refers to the state when viewed along the negative direction in the "depth direction" shown in FIG. 1. The above-mentioned "positive direction" refers to the direction of the arrows in the long axis direction, short axis direction, and depth direction shown in Figures 1 to 7, and the "negative direction" refers to the direction opposite to the direction of the arrows in the long axis direction, short axis direction, and depth direction shown in Figures 1 to 7.

[0012] -First embodiment of the battery pack of the present disclosure- A first embodiment of a battery pack according to the present disclosure will be described with reference to Figures 1 to 3. The battery pack 100 according to the present disclosure includes a battery case 1 as a main component (see Figure 1). In addition, the battery pack 100 may include, as secondary components, cylindrical battery cells 10 housed in the battery case 1, tabs 20 that electrically connect the housed cylindrical battery cells 10, and an exterior member 30 that houses the battery case 1. The components of the battery pack 100 according to the present disclosure will be described in detail below.

[0013] Battery case The battery case 1 has multiple storage sections 11 that accommodate one cylindrical battery cell 10. In the example shown in FIG. 2, the number of storage sections 11 is five, but the number is not limited to the above example as long as there are two or more storage sections 11. As an example, the number of storage sections 11 may be two as shown in FIG. 3. The storage sections 11 are arranged side by side in one direction. In this specification, the direction in which the storage sections 11 are arranged is defined as the long axis direction, and the direction perpendicular to the long axis direction is defined as the short axis direction. The direction perpendicular to the long axis direction and the short axis direction and parallel to the central axis of the cylindrical battery cell 10 is defined as the depth direction.

[0014] The storage section 11 has a wall 12 that defines a space for storing the cylindrical battery cell 10. Before the cylindrical battery cell 10 is stored in the storage section 11, the space is elliptical in front view. However, the shape of the space is not limited to ellipse because the wall 12 is deformed by the cylindrical battery cell 10 after the cylindrical battery cell 10 is stored in the storage section 11. In FIG. 2 , which shows an example, the elliptical storage section 11 has a major axis diameter L1 and a minor axis diameter L2. In this specification, the "major axis diameter L1" is synonymous with the longest length in the major axis direction of the elliptical storage section 11 before the cylindrical battery cell 10 is stored in the storage section 11, and the "minor axis diameter L2" is synonymous with the longest length in the minor axis direction of the elliptical storage section 11 before the cylindrical battery cell 10 is stored in the storage section 11. The major axis diameter L1 is longer than the minor axis diameter L2.

[0015] The walls 12 of adjacent storage sections 11 may be connected to each other. In other words, the walls 12 may be integrated as a single member. Designing the walls 12 in this manner makes it easier to handle the walls 12.

[0016] The wall 12 has a slit 13 formed parallel to the central axis C of the elliptical cylindrical space. Note that the "central axis of the elliptical cylindrical space" in this specification refers to an axis that passes through the center of the elliptical cylindrical space and extends parallel to the depth direction. In other words, the slit 13 is formed parallel to the depth direction. The wall 12 may be made of any elastically deformable material, but a resin material is preferred. Furthermore, the resin material preferably has the following material properties: a tensile strength of 15 MPa or more, a bending strength of 15 MPa or more, or a bending modulus of elasticity of 4000 MPa or less. Therefore, the wall 12 with the slit 13 formed therein can be elastically deformed in the minor axis direction when the cylindrical battery cell 10 is placed in the storage section 11.

[0017] One characteristic feature of the battery pack 100 of the present disclosure is that the minor axis diameter L2 of the elliptical cylindrical space provided in the housing portion 11 is equal to or smaller than the diameter of the cylindrical battery cell 10.

[0018] In this specification, the term "diameter of the cylindrical battery cell 10" literally refers to the diameter of the cylindrical battery cell 10, but also encompasses the minimum diameter dimension of the dimensional tolerance of the cylindrical battery cell 10. In this specification, the dimensional tolerance refers to a difference of ±2% of the diameter of the cylindrical battery cell 10.

[0019] According to the battery pack 100 of the present disclosure, when a cylindrical battery cell 10 is accommodated in the accommodation section 11, the wall section 12 elastically deforms so as to widen the gap of the slit 13. Then, because the minor axis diameter L2 of the elliptical cylindrical space is equal to or less than the diameter of the cylindrical battery cell 10, the elliptical cylindrical space elastically deforms in the minor axis direction. Then, because an elastic force is generated in the minor axis direction by the elastic deformation, the cylindrical battery cell is sandwiched between the wall section 12 in the minor axis direction. Therefore, the elastically deformed wall section 12 can be appropriately brought into close contact with the outer peripheral surface of the cylindrical battery cell 10.

[0020] In a preferred embodiment of the accommodation section 11, the major axis diameter L1 of the elliptical cylindrical space may be equal to or greater than the diameter of the cylindrical battery cell 10. By setting the major axis diameter L1 of the elliptical cylindrical space as described above, elastic deformation of the accommodation sections 11 in a direction in which the cylindrical battery cells 10 are aligned (the major axis direction) can be prevented even when the cylindrical battery cells 10 are accommodated in the battery case 1. In other words, even if one cylindrical battery cell 10 is accommodated in an accommodation section 11 and another cylindrical battery cell 10 is accommodated in an adjacent accommodation section 11, elastic deformation of the accommodation sections 11 in the major axis direction is suppressed because the major axis diameter L1 is equal to or greater than the diameter of the cylindrical battery cell 10. This makes it difficult for the distance between the central axis of one cylindrical battery cell 10 and the central axis of the other cylindrical battery cell 10 to change, and the distance between the central axis of one cylindrical battery cell 10 and the central axis of the other cylindrical battery cell 10 can be maintained constant. The "central axis of the cylindrical battery cell" refers to an axis that passes through the center of the cylindrical battery cell 10 and extends parallel to the depth direction described above.

[0021] Furthermore, in a preferred embodiment of the accommodation section 11, when a cylindrical battery cell 10 is accommodated in the elliptical cylindrical space, the central axis C of the elliptical cylindrical space may coincide with the central axis of the cylindrical battery cell 10. Furthermore, as described above, in the long axis direction of the elliptical cylindrical space, the long axis diameter L1 of the space is equal to or greater than the diameter of the cylindrical battery cell 10. Therefore, even if one cylindrical battery cell 10 is accommodated in the accommodation section 11 and another cylindrical battery cell 10 is accommodated in the adjacent accommodation section 11, the central axis C of the elliptical cylindrical space coincides with the central axis of the cylindrical battery cell 10. Furthermore, the distance between the central axis of one cylindrical battery cell 10 and the adjacent cylindrical battery cell 10 is less likely to change, making it easier to position the cylindrical battery cell 10 relative to the tab 20, which will be described later.

[0022] In addition, in a preferred embodiment of the storage section 11, the depth direction length of the storage section 11 may be equal to or greater than the depth direction length of the cylindrical battery cells 10. By designing the length of the storage section 11 in the central axis direction in this manner, the contact area between the cylindrical battery cells 10 stored in the storage section 11 and the wall section 12 of the storage section 11 increases, thereby improving heat transfer efficiency.

[0023] In the present embodiment shown in FIG. 2 , the slits 13 are provided in the boundary region A between adjacent storage sections 11. In this specification, the term "boundary region" refers to the boundary position Ap between adjacent storage sections 11 and the region extending from the boundary position Ap up to a length ΔA that is ±10% of the major axis diameter L1. In the present embodiment shown in FIG. 2 , the slits 13 are provided in the boundary region A between adjacent storage sections 11 in all storage sections 11 except the central storage section 11, so that the entire area above the cylindrical battery cells 10 can be covered by the wall section 12. Therefore, by providing the slits 13 in the boundary region A, the cylindrical battery cells 10 can be properly brought into close contact with the wall section 12.

[0024] In addition, in this embodiment shown in Figure 2, the slits 13 provided in the centrally located storage section 11 are positioned so as to overlap the central axis C of the storage section 11 in a plan view of the battery case 1. As mentioned above, a plan view refers to a state when viewed along the negative direction in the minor axis direction shown in Figure 1. Providing the slits 13 in this manner makes it easy to accommodate cylindrical battery cells 10 in the centrally located storage section 11.

[0025] In the present embodiment shown in FIG. 2 , the slits 13 formed in the multiple housing sections 11 are plane-symmetrical with respect to a bisecting plane P of the battery case 1, which is parallel to the minor axis diameter L2 of the elliptical cylindrical space. The term "bisecting plane" used herein refers to a plane that includes a perpendicular bisector that bisects the length D (see FIG. 2 ) parallel to the major axis direction of the battery case 1 and is perpendicular to the major axis direction of the battery case 1. Furthermore, the term "plane-symmetrical" used herein refers to an object that, when cut along the bisecting plane P, has two halves that have substantially the same shape. By providing the slits 13 with plane symmetry in this way, the elastic deformation of the wall sections 12 is symmetrical in the direction in which the housing sections 11 are arranged, thereby further improving the adhesion between the wall sections 12 and the cylindrical battery cells 10. This facilitates the transfer of heat generated by the cylindrical battery cells 10 to the battery case 1, thereby further improving the heat dissipation of the cylindrical battery cells 10.

[0026] 2, the slits 13 formed in the plurality of housing portions 11 are positioned above the major axis diameter L1 of the ellipse in a front view (in the positive direction of the minor axis in FIG. 2). In other words, the slits 13 are positioned in the same direction (upper side) as the positive direction of the minor axis. By providing the slits 13 in this manner, the elastic deformation of the wall portions 12 can be aligned in the same direction, thereby generating appropriate elastic deformation.

[0027] Furthermore, in the present embodiment shown in FIG. 2, the minor axis diameter L2 is preferably a length that is 90% or more of the diameter of the cylindrical battery cell 10 accommodated in the accommodation section 11. More preferably, it is preferably no more than 100% of the diameter of the cylindrical battery cell 10 accommodated in the accommodation section 11. Having the minor axis diameter L2 as described above provides the following advantageous effects. The accommodation section 11 has a slit 13, and the minor axis diameter L2 is the above-described length. This allows the accommodation section 11 (wall 12) to elastically deform when the cylindrical battery cell 10 is accommodated so that the space for accommodating the cylindrical battery cell 10 expands to an extent that prevents the cylindrical battery cell 10 from cracking. This prevents the battery case 1 (wall 12) from cracking when the cylindrical battery cell 10 is accommodated in the accommodation section 11.

[0028] Furthermore, by setting the minor axis diameter L2 as described above, the contact area between the wall portion 12 and the surface of the cylindrical battery cell 10 can be increased. First, as a comparative example, a case will be described in which the minor axis diameter L2 is a length that is less than 90% of the diameter of the cylindrical battery cell 10 accommodated in the accommodation portion 11. In this case, when the cylindrical battery cell 10 is accommodated in the accommodation portion 11, the width (length in the major axis direction) of the slit 13 is further expanded compared to this embodiment. In other words, the contact area between the wall portion 12 and the cylindrical battery cell 10 is reduced. This makes it more difficult for heat generated by the cylindrical battery cell 10 to be transferred to the battery case 1.

[0029] In contrast, in this embodiment, by setting the minor axis diameter L2 as described above, it is possible to minimize the expansion of the width (length in the major axis direction) of the slit 13 when the cylindrical battery cell 10 is housed in the housing portion 11. In other words, it is possible to increase the contact area between the wall portion 12 and the surface of the cylindrical battery cell 10 compared to the comparative example. This makes it easier to transfer heat generated by the cylindrical battery cell 10 to the battery case 1, further improving the heat dissipation performance of the cylindrical battery cell 10.

[0030] Cylindrical battery cells The cylindrical battery cell 10, which is a secondary component of the present disclosure, is housed in the housing portion 11 of the battery case 1 described above. The cylindrical battery cell 10 is intended to be a chemical battery that primarily converts chemical energy into direct current power through a chemical reaction, but it may also be a physical battery that generates electricity from physical energy such as heat or light.

[0031] As described above, the cylindrical battery cells 10 have a predetermined dimensional tolerance. However, cylindrical battery cells 10 that do not have dimensional tolerances may also be used.

[0032] In a preferred embodiment of the cylindrical battery cell 10, the metal can may be exposed on the outer circumferential surface of the cylindrical battery cell 10. Exposing the metal can facilitates heat transfer from the exposed metal to the wall 12, thereby improving the heat transfer efficiency between the cylindrical battery cell 10 with the exposed metal can and the wall 12 of the housing section 11 compared to a cylindrical battery cell 10 covered with shrink film. Furthermore, because the outer circumferential surface of the cylindrical battery cell 10 is exposed without being covered with shrink film or the like, the dimensional tolerance of the cylindrical battery cell 10 can also be reduced. Note that the embodiment is not limited to the above, and the outer circumferential surface of the cylindrical battery cell 10 may also be covered with shrink film or the like.

[0033] ·tab The tabs 20, which are a secondary component of the present disclosure, electrically connect adjacent cylindrical battery cells 10 housed in the housing portion 11. The tabs 20 may electrically connect the cylindrical battery cells 10 in series. Alternatively, the tabs 20 may electrically connect the cylindrical battery cells 10 in parallel. In other words, since the tabs 20 electrically connect to the cylindrical battery cells 10, they are preferably made of a material with good electrical conductivity. As an example, metal is preferred. By providing the tabs 20 in this manner, adjacent cylindrical battery cells 10 can be electrically connected in series or parallel with the wall portions 12 in appropriate contact with the outer circumferential surfaces of the cylindrical battery cells 10.

[0034] Furthermore, as described above, if the central axis C of the elliptically extending space in the storage section 11 coincides with the central axis of the cylindrical battery cell 10, the distance between the central axis C of one cylindrical battery cell 10 and the central axis of the adjacent cylindrical battery cell 10 is less likely to change when the cylindrical battery cell 10 is stored in the storage section 11. This makes it easier to tab the cylindrical battery cells 10 together using the tabs 20 that electrically connect them.

[0035] Exterior materials The exterior member 30, which is a secondary component of the present disclosure, is used to house the above-described battery case 1. The exterior member 30 may be made of any material as long as it can house the battery case 1, but in consideration of the safety of the battery pack 100, it is preferable to use an insulating material.

[0036] Furthermore, the exterior member 30 may be provided with a connector or the like for extracting the power generated by the cylindrical battery cells 10 housed inside.

[0037] As described above, according to the battery pack 100 of the present disclosure, the wall 12 defining the space that houses the cylindrical battery cell 10 has a slit 13 formed parallel to the central axis C of the elliptical cylindrical space, and the minor axis diameter L2 of the elliptical cylindrical space is equal to or smaller than the diameter of the cylindrical battery cell 10, so that the wall 12 divided by the slit 13 can be properly adhered to the outer peripheral surface of the cylindrical battery cell 10.

[0038] -Second embodiment of the battery pack of the present disclosure- A second embodiment of the battery pack of the present disclosure will be described with reference to Figures 4 and 5. The second embodiment differs from the first embodiment described above in the position of the slit 13 provided in the wall portion 12. The other configurations are basically the same as those of the first embodiment described above. The different configurations will be described below.

[0039] In this embodiment, the slit 13 (13a) provided in the outermost storage section 11 (hereinafter referred to as the outermost storage section 11a) among the multiple storage sections 11 is arranged to overlap with the central axis C1 of the elliptical cylindrical space in the storage section 11a when viewed from the side of the battery pack 100.

[0040] By positioning the slit 13a of the outermost housing portion 11a in the above position, it is possible to suppress fluctuations in the position of the outermost housing portion 11a in the short axis direction before and after the cylindrical battery cell 10 is housed in the outermost housing portion 11a.

[0041] In this embodiment, the slits 13 (13b, 13c) provided in the housing sections 11 (11b, 11c) located more inward than the outermost housing section 11a among the multiple housing sections 11 are provided at positions overlapping the central axes C (C2, C3) of the housing sections 11 in a plan view of the battery case 1. In FIG. 5 showing an example, the slit 13b of the housing section 11b located in the center (hereinafter referred to as the central housing section 11b) is provided below the central housing section 11b (in the negative direction of the minor axis in FIG. 5). In contrast, the slit 13c of the housing section 11c (hereinafter referred to as the intermediate housing section 11c) between the central housing section 11b and the outermost housing section 11a is provided above the intermediate housing section 11c (in the positive direction of the minor axis in FIG. 5).

[0042] The effects of the above configuration will be explained with reference to Figure 5. First, when a cylindrical battery cell 10 is accommodated in the central accommodation section 11b, the slit 13b expands. As a result, the intermediate accommodation section 11c and the outermost accommodation section 11a move in the positive direction of the minor axis in Figure 5. In other words, the arrangement of the accommodation sections 11a-11c of the battery case 1 when viewed from the direction of the central axes C1-C3 is V-shaped (not shown).

[0043] Subsequently, when a cylindrical battery cell 10 is accommodated in the intermediate accommodation section 11c, the slit 13c expands, causing the outermost accommodation section 11a to move in the negative direction in the minor axis direction in Figure 5 (not shown).

[0044] Finally, even when cylindrical battery cells 10 are accommodated in the outermost housing sections 11a, fluctuations in the position of the outermost housing sections 11a (fluctuations in the minor axis direction in FIG. 5) are suppressed, as explained above. Note that the order in which the cylindrical battery cells 10 are accommodated in the housing sections 11a is not limited to the above-mentioned order of the central housing section 11b, the intermediate housing section 11c, and the outermost housing section 11a. For example, the cylindrical battery cells 10 may be accommodated in the outermost housing section 11a first, or the cylindrical battery cells 10 may be accommodated in the intermediate housing section 11b first.

[0045] These actions make it possible to suppress deformation of the battery case 1 before and after the cylindrical battery cells 10 are accommodated (in other words, deformation of the battery case 1 as a whole in the up-and-down direction (short axis direction)).

[0046] Furthermore, in this embodiment, among the multiple storage sections 11, the storage sections 11b and 11c are located inside the outermost storage section 11a, and the slits 13 of the adjacent storage sections 11 are staggered when viewed from the front of the battery case 1. In this specification, "staggered" refers to the slit positions overlapping when the adjacent storage sections 11 are rotated 180° around the center of the storage sections 11. This configuration can distribute the stress on the cylindrical battery cells 10 caused by the wall sections 12, allowing all of the cylindrical battery cells 10 to fit more closely to the battery case 1. Furthermore, since the left and right battery cases 1 can be made to deform similarly around the central storage section 11b, deformation of the battery case 1 in the vertical direction (the minor axis direction in FIG. 5 ) can be suppressed.

[0047] 5, which shows an example of this embodiment, the slits 13c of the intermediate storage portions 11c are formed on the upper side (positive direction in the minor axis direction) and the slits 13b of the central storage portion 11b are formed on the lower side (negative direction in the minor axis direction), but this is not limiting. For example, the same effect can be achieved by forming the slits 13c of the intermediate storage portions 11c on the lower side (negative direction in the minor axis direction) and the slits 13b of the central storage portion 11b on the upper side (positive direction in the minor axis direction).

[0048] -Third embodiment of the battery pack of the present disclosure- A third embodiment of the battery pack of the present disclosure will be described with reference to Figures 6 and 7. The third embodiment differs from the first and second embodiments described above in that a connecting member is provided to connect the walls of the outermost housing sections. The other configurations are basically the same as those of the first and second embodiments described above. The different configurations will be described below.

[0049] Connection parts The connecting member 40 of this embodiment connects the wall portions 12 of the outermost housing portions 11 together. Providing the connecting member 40 can improve the strength of the battery case 1. Furthermore, by connecting the wall portions 12 of the outermost housing portions 11 together using the connecting member 40, deformation of the battery case 1 in the longitudinal direction can be reduced. In other words, deformation of the entire battery case 1 can be suppressed.

[0050] The material of the connecting member 40 is preferably the same resin material as the material of the wall portion 12 described above, but a material different from the material of the wall portion 12 may also be used.

[0051] The connection member 40 may also be provided with a control circuit for controlling the power of the cylindrical battery cells 10. In other words, the connection member 40 can also function as a member for mounting the control circuit. Therefore, by providing the connection member 40 as in this embodiment, the surface area can be used effectively.

[0052] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. The technical scope of the present disclosure also includes all modifications within the scope and meaning equivalent to the claims.

[0053] The battery pack of the present disclosure includes the following aspects. <1> A battery pack including a battery case having a plurality of housing sections each housing a single cylindrical battery cell, the housing sections being arranged in a line in one direction, the housing portion has a wall portion that defines a space for housing the cylindrical battery cell; the wall portion defines an elliptical cylindrical space before the cylindrical battery cell is housed therein; a slit is provided in the wall portion parallel to the central axis of the elliptical cylindrical space, The direction in which the storage sections are arranged in one direction is defined as the long axis direction of the elliptical cylindrical space, the direction perpendicular to the long axis direction is defined as the short axis direction, and the direction perpendicular to the long axis direction and the short axis direction and parallel to the central axis of the elliptical cylindrical space is defined as the depth direction, a diameter of the cylindrical battery cell that is equal to or smaller than the diameter of the cylindrical battery cell, the diameter being the longest minor axis of the elliptical cylindrical space in the accommodation portion. <2> <1> The battery pack according to claim 1, The battery pack includes tabs that electrically connect adjacent cylindrical battery cells to each other. <3> <1> or <2> The battery pack according to claim 1, When the cylindrical battery cells are housed in the housing sections, the central axes of the housing sections and the cylindrical battery cells are aligned. <4> <1> ~ <3> The battery pack according to any one of the above items, The battery pack, wherein the longest major axis diameter in the major axis direction of the elliptical cylindrical space is equal to or greater than the diameter of the cylindrical battery cell. <5> <1> ~ <4> The battery pack according to any one of the above items, The slit is provided in a boundary region between the adjacent storage sections. <6> <1> ~ <5> The battery pack according to any one of the above items, A battery pack, wherein the slit formed in the central storage portion is positioned so as to overlap with the central axis of the elliptical cylindrical space in the storage portion when the battery case is viewed in plan. <7> <1> ~ <6> The battery pack according to any one of the above items, the slits formed in the plurality of housing sections are plane-symmetrical with respect to a plane that bisects the battery case and is parallel to the minor axis diameter of the elliptical cylindrical space. <8> <1> ~ <7> The battery pack according to any one of the above items, a slit provided in the outermost storage section among the plurality of storage sections is provided at a position that overlaps with the central axis of the elliptical cylindrical space in the storage section when viewed from the side of the battery case. <9> <1> ~ <8> The battery pack according to any one of the above items, A battery pack, wherein a slit provided in a storage section located more inward than the outermost storage section among the plurality of storage sections is provided at a position that overlaps with the central axis of the elliptical cylindrical space in the storage section when viewed in a plane of the battery case. <10> <1> ~ <9> The battery pack according to any one of the above items, In the battery pack, in the housing sections located more inward than the outermost housing sections among the plurality of housing sections, the slits of adjacent housing sections are staggered when viewed from the front of the battery case. <11> <1> ~ <10> The battery pack according to any one of the above items, A battery pack having a connecting member that connects wall portions of the outermost storage portion. <12> <1> ~ <11> The battery pack according to any one of the above items, A battery pack, wherein a metal can is exposed on the outer circumferential surface of the cylindrical battery cell. <13> <1> ~ <12> The battery pack according to any one of the above items, a length of the housing portion in the depth direction that is equal to or greater than a length of the cylindrical battery cell in the depth direction. <14> <1> ~ <13> The battery pack according to any one of the above items, The battery pack has wall portions of the adjacent storage portions connected to each other. <15> <1> ~ <14> The battery pack according to any one of the above items, A battery pack, wherein the minor axis diameter is a length that is 90% or more of the diameter of the cylindrical battery cell. [Industrial Applicability]

[0054] The present disclosure can be used in a battery pack with improved adhesion to cylindrical battery cells. [Explanation of symbols]

[0055] 1 Battery case 10 Cylindrical battery cells 11, 11a to 11c Storage section 12 Wall 13, 13a~13c Slit 20 tabs 30 Exterior materials 40 Connecting member 100 battery packs A boundary area Ap Boundary position C1~C3 center axis L1 major axis diameter L2 short axis diameter P bisector

Claims

1. A battery pack including a battery case having a plurality of housing sections each housing a single cylindrical battery cell, the housing sections being arranged in a line in one direction, the housing portion has a wall portion that defines a space for housing the cylindrical battery cell; the wall portion defines an elliptical cylindrical space before the cylindrical battery cell is housed therein; a slit is provided in the wall portion parallel to the central axis of the elliptical cylindrical space, The direction in which the storage sections are arranged in one direction is defined as the long axis direction of the elliptical cylindrical space, the direction perpendicular to the long axis direction is defined as the short axis direction, and the direction perpendicular to the long axis direction and the short axis direction and parallel to the central axis of the elliptical cylindrical space is defined as the depth direction, a diameter of the cylindrical battery cell that is equal to or smaller than the diameter of the cylindrical battery cell, the diameter being the longest minor axis of the elliptical cylindrical space in the accommodation portion.

2. 2. The battery pack according to claim 1, The battery pack includes tabs that electrically connect adjacent cylindrical battery cells to each other.

3. 2. The battery pack according to claim 1, When the cylindrical battery cells are housed in the housing sections, the central axes of the housing sections and the cylindrical battery cells are aligned.

4. 2. The battery pack according to claim 1, The battery pack, wherein the longest major axis diameter in the major axis direction of the elliptical cylindrical space is equal to or greater than the diameter of the cylindrical battery cell.

5. 2. The battery pack according to claim 1, The slit is provided in a boundary region between the adjacent storage sections.

6. 2. The battery pack according to claim 1, A battery pack, wherein the slit formed in the central storage portion is positioned so as to overlap with the central axis of the elliptical cylindrical space in the storage portion when the battery case is viewed in plan.

7. 2. The battery pack according to claim 1, The slits formed in the plurality of housing sections are plane-symmetrical with respect to a plane that bisects the battery case and is parallel to the minor axis diameter of the elliptical cylindrical space.

8. 2. The battery pack according to claim 1, a slit provided in the outermost storage section among the plurality of storage sections is provided at a position that overlaps with the central axis of the elliptical cylindrical space in the storage section when viewed from the side of the battery case.

9. 2. The battery pack according to claim 1, A battery pack, wherein a slit provided in a storage section located more inward than an outermost storage section among the plurality of storage sections is provided at a position that overlaps with the central axis of the elliptical cylindrical space in the storage section when viewed in a plane of the battery case.

10. 2. The battery pack according to claim 1, In the battery pack, in the housing sections located more inward than the outermost housing sections among the plurality of housing sections, the slits of adjacent housing sections are staggered when viewed from the front of the battery case.

11. 2. The battery pack according to claim 1, A battery pack having a connecting member that connects wall portions of the outermost storage portion.

12. 2. The battery pack according to claim 1, A battery pack in which a metal can is exposed on the outer periphery of the cylindrical battery cell.

13. 2. The battery pack according to claim 1, a length of the housing portion in the depth direction that is equal to or greater than a length of the cylindrical battery cell in the depth direction.

14. 2. The battery pack according to claim 1, The battery pack has wall portions of the adjacent storage portions connected to each other.

15. 2. The battery pack according to claim 1, A battery pack, wherein the minor axis diameter is a length that is 90% or more of the diameter of the cylindrical battery cell.

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