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

Battery pack

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

[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 being formed by a roughly cylindrical wall section that has spring properties that allow it to expand in diameter when a battery is inserted.

[0003] Japanese Patent Application Laid-Open No. 2016-207569

[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.

[0006] The battery pack according to the present disclosure is a battery pack comprising a battery case having a plurality of storage sections each accommodating one cylindrical battery cell, the storage sections being arranged in a line in one direction, wherein the storage section has a wall section defining a space for accommodating the cylindrical battery cell, the wall section defining an elliptical cylindrical space before the cylindrical battery cell is accommodated in the battery case, a slit being provided in the wall section parallel to the central axis of the elliptical cylindrical space, the direction in which the storage sections are arranged in one direction being the long axis direction of the elliptical cylindrical space, a direction perpendicular to the long axis direction being the short axis direction, a direction perpendicular to the long axis direction and the short axis direction and parallel to the central axis of the elliptical cylindrical space being the depth direction, and the longest short axis diameter in the short axis direction of the elliptical cylindrical space in the storage section being equal to or less than the diameter of the cylindrical battery cell.

[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.

[0008] FIG. 1 is a perspective view schematically showing a first embodiment of a battery pack according to the present disclosure; FIG. 2 is a front view of a battery case according to the first embodiment, viewed from an axial direction; FIG. 3 is a front view of a battery case according to a modified example of the first embodiment, viewed from an axial direction; FIG. 4 is a perspective view schematically showing a second embodiment of a battery pack according to the present disclosure; FIG. 5 is a front view of a battery case according to the second embodiment, viewed from an axial direction; FIG. 6 is a perspective view schematically showing a third embodiment of a battery pack according to the present disclosure; FIG. 7 is a front view of a battery case according to the third embodiment, viewed from an axial direction.

[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 . As used herein, 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 . As used herein, 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 Battery Pack of the Present Disclosure A first embodiment of a battery pack of the present disclosure will be described with reference to Figures 1 to 3. A battery pack 100 of 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 of the present disclosure will be described in detail below.

[0013] Battery Case The battery case 1 has multiple storage sections 11 that store a single 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 lined up 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 housing section 11 has a wall 12 that defines a space for housing the cylindrical battery cell 10. Before housing the cylindrical battery cell 10, 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 housing the cylindrical battery cell 10. In FIG. 2 , which shows an example, the elliptical housing 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 housing section 11 before housing the cylindrical battery cell 10, and the "minor axis diameter L2" is synonymous with the longest length in the minor axis direction of the elliptical housing section 11 before housing the cylindrical battery cell 10. 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. In this specification, the "central axis of the elliptical cylindrical space" 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 is elastically deformable 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, and 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 portion 11, the wall portion 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 portion 12 in the minor axis direction. Therefore, the elastically deformed wall portion 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] In addition, 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, as described below.

[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 Figure 2, the slits 13 are provided in the boundary region A between adjacent housing sections 11. In this specification, the term "boundary region" refers to the boundary position Ap between adjacent housing sections 11 and the region extending from the boundary position Ap up to a length ΔA of ±10% of the major axis diameter L1. In the present embodiment shown in Figure 2, the slits 13 are provided in the boundary region A between adjacent housing sections 11 in all housing sections 11 except the central housing 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 the present 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, the plan view refers to the 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" as 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" as 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 manner, 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] In the present embodiment shown in Fig. 2, the slits 13 provided in the plurality of accommodation sections 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 sections 12 can be aligned in the same direction, thereby enabling appropriate elastic deformation to occur.

[0027] Furthermore, in the present embodiment shown in FIG. 2 , the minor axis diameter L2 is preferably at least 90% of the diameter of the cylindrical battery cell 10 accommodated in the accommodation section 11. More preferably, it is less than 100% of the diameter of the cylindrical battery cell 10 accommodated in the accommodation section 11. Having the above-described minor axis diameter L2 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 a degree that prevents 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 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, the minor axis diameter L2 is set as described above, which minimizes 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, the contact area between the wall portion 12 and the surface of the cylindrical battery cell 10 can be made larger than in 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 Cell 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. 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 a dimensional tolerance 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 metal can is exposed without being covered with a shrink film or the like on the outer circumferential surface of the cylindrical battery cell 10, 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 a shrink film or the like.

[0033] Tabs 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 each other while the wall portions 12 are 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 housing 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 housed in the housing section 11. This makes it easier to tab the cylindrical battery cells 10 together using the tabs 20 that electrically connect them.

[0035] Exterior member 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 portion 12 that defines 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 portion 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 storage section 11a at the above position, fluctuations in the position of the outermost storage section 11a in the short axis direction before and after storing the cylindrical battery cell 10 in the outermost storage section 11a can be suppressed.

[0041] In this embodiment, the slits 13 (13b, 13c) provided in the accommodation portions 11 (11b, 11c) located more inward than the outermost accommodation portion 11a among the plurality of accommodation portions 11 are provided at positions overlapping with the central axes C (C2, C3) of the accommodation portions 11 in a plan view of the battery case 1. In FIG. 5 showing an example, the slit 13b of the accommodation portion 11b located in the center (hereinafter referred to as the central accommodation portion 11b) is provided below the central accommodation portion 11b (in the negative direction of the minor axis in FIG. 5). In contrast, the slit 13c of the accommodation portion 11c (hereinafter referred to as the intermediate accommodation portion 11c) between the central accommodation portion 11b and the outermost accommodation portion 11a is provided above the intermediate accommodation portion 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 to 11c of the battery case 1 when viewed from the direction of the central axes C1 to C3 is V-shaped (not shown).

[0043] Next, 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 accommodation section 11a, fluctuations in the position of the outermost accommodation section 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 accommodation sections 11a is not limited to the above-mentioned order of the central accommodation section 11b, the intermediate accommodation section 11c, and the outermost accommodation section 11a. For example, the cylindrical battery cells 10 may be accommodated in the outermost accommodation section 11a first, or the cylindrical battery cells 10 may be accommodated in the intermediate accommodation 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 entire battery case 1 in the up-and-down direction (short axis direction)).

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

[0047] 5, which illustrates 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 rest of the configuration is basically the same as the first and second embodiments described above. This different configuration will be described below.

[0049] Connecting Member The connecting member 40 of this embodiment connects the wall portions 12 of the outermost housing portions 11 together. By providing the connecting member 40, the strength of the battery case 1 can be improved. 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 effectively utilized.

[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 accommodation sections that accommodate one cylindrical battery cell, the accommodation sections being arranged side by side in one direction, wherein the accommodation section has a wall that defines a space that accommodates the cylindrical battery cell, the wall defining an elliptical cylindrical space before the cylindrical battery cell is accommodated in the battery case, a slit is formed in the wall parallel to the central axis of the elliptical cylindrical space, the direction in which the accommodation sections are arranged in one direction is the long axis direction of the elliptical cylindrical space, a direction perpendicular to the long axis direction is the short axis direction, and a 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 accommodation section is equal to or less than the diameter of the cylindrical battery cell. <2> The battery pack according to <1>, further including a tab that electrically connects adjacent cylindrical battery cells to each other. <3> The battery pack according to <1> or <2>, wherein, when the cylindrical battery cells are accommodated in the accommodation sections, the central axis of the accommodation sections coincides with the central axis of the cylindrical battery cells. <4> The battery pack according to any one of <1> to <3>, wherein the longest major axis diameter in the major axis direction of the elliptical cylindrical space is equal to or longer than the diameter of the cylindrical battery cells. <5> The battery pack according to any one of <1> to <4>, wherein the slit is provided in a boundary region between adjacent accommodation sections. <6> The battery pack according to any one of <1> to <5>, wherein the slit formed in a central accommodation section is provided in a position that overlaps with the central axis of the elliptical cylindrical space in the accommodation section in a plan view of the battery case. <7> The battery pack according to any one of <1> to <6>, wherein the slits formed in the plurality of housing sections are plane-symmetrical with respect to a bisecting plane of the battery case that is parallel to the minor axis diameter of the elliptical cylindrical space.<8> The battery pack according to any one of <1> to <7>, wherein a slit provided in an outermost storage section among the plurality of storage sections is positioned so as to overlap with the central axis of the elliptical cylindrical space in the storage section in a side view of the battery case. <9> The battery pack according to any one of <1> to <8>, wherein a slit provided in an storage section located more inward than the outermost storage section among the plurality of storage sections is positioned so as to overlap with the central axis of the elliptical cylindrical space in the storage section in a plan view of the battery case. <10> The battery pack according to any one of <1> to <9>, wherein, in a storage section located more inward than the outermost storage section among the plurality of storage sections, the slits of adjacent storage sections are staggered in a front view of the battery case. <11> The battery pack according to any one of <1> to <10>, comprising a connecting member that connects wall sections of the outermost storage sections together. <12> The battery pack according to any one of <1> to <11>, wherein a metal can is exposed from the outer peripheral surface of the cylindrical battery cell. <13> The battery pack according to any one of <1> to <12>, wherein the length of the storage section in the depth direction is equal to or greater than the length of the cylindrical battery cell in the depth direction. <14> The battery pack according to any one of <1> to <13>, wherein wall portions of adjacent storage sections are connected to each other. <15> The battery pack according to any one of <1> to <14>, wherein the minor axis diameter is equal to or greater than 90% of the diameter of the cylindrical battery cell.

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

[0055] REFERENCE SIGNS LIST 1 battery case 10 cylindrical battery cell 11, 11a to 11c storage section 12 wall section 13, 13a to 13c slit 20 tab 30 exterior member 40 connection member 100 battery pack A boundary region Ap boundary position C1 to C3 central axis L1 major axis diameter L2 minor axis diameter P bisecting plane

Claims

1. A battery pack comprising a plurality of accommodating portions for accommodating one cylindrical battery cell, and a battery case in which the accommodating portions are arranged side by side in one direction, The accommodating portion has a wall portion that defines a space for accommodating the cylindrical battery cell, The wall portion in the state before accommodating the cylindrical battery cell defines an elliptical columnar space, In the wall portion, a slit is provided parallel to the central axis of the elliptical columnar space, The direction in which the accommodating portions are arranged side by side in one direction is defined as the major axis direction of the elliptical columnar space, the direction perpendicular to the major axis direction is defined as the minor axis direction, and the direction perpendicular to the major axis direction and the minor axis direction and parallel to the central axis of the elliptical columnar space is defined as the depth direction, A battery pack, wherein the longest minor axis diameter in the minor axis direction of the elliptical columnar space in the accommodating portion is equal to or less than the diameter of the cylindrical battery cell.

2. The battery pack according to claim 1, comprising a tab for electrically connecting adjacent cylindrical battery cells.

3. The battery pack according to claim 1, wherein the central axis of the accommodating portion coincides with the central axis of the cylindrical battery cell when the cylindrical battery cell is accommodated in the accommodating portion.

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

5. The battery pack according to claim 1, wherein the slit is provided in a boundary region between adjacent accommodating portions.

6. The battery pack according to claim 1, The slit formed in the accommodating portion located at the center is provided at a position overlapping the central axis of the elliptical columnar space in the accommodating portion in a plan view of the battery case, the battery pack.

7. The battery pack according to claim 1, The slits formed in the plurality of accommodating portions are plane-symmetric with respect to the bisecting plane of the battery case parallel to the minor axis diameter of the elliptical columnar space, the battery pack.

8. The battery pack according to claim 1, The slit provided in the outermost accommodating portion among the plurality of accommodating portions is provided at a position overlapping the central axis of the elliptical columnar space in the accommodating portion in a side view of the battery case, the battery pack.

9. The battery pack according to claim 1, The slit provided in the accommodating portion located inside the outermost accommodating portion among the plurality of accommodating portions is provided at a position overlapping the central axis of the elliptical columnar space in the accommodating portion in a plan view of the battery case, the battery pack.

10. The battery pack according to claim 1, In the accommodating portion located inside the outermost accommodating portion among the plurality of accommodating portions, the slits of the adjacent accommodating portions are staggered in a front view of the battery case, the battery pack.

11. The battery pack according to claim 1, Having a connecting member that connects the wall portions of the outermost accommodating portions, the battery pack.

12. The battery pack according to claim 1, The outer peripheral surface of the cylindrical battery cell has a metal can exposed, the battery pack.

13. The battery pack according to claim 1, The length of the accommodation part in the depth direction is equal to or greater than the length of the cylindrical battery cell in the depth direction, battery pack.

14. The battery pack according to claim 1, wherein the wall portions of adjacent accommodation parts are connected to each other, battery pack.

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