Battery pack

Abstract

The objective of the present invention is to suppress situations in which a flame leaks to the outside in the event of an abnormality.　This battery pack is provided with a first inorganic plate which is disposed in an opening of a casing, and which is disposed spaced apart from a battery holder by a first gap d1, and a second inorganic plate which is spaced apart from the first inorganic plate by a second gap d2. The first inorganic plate has a plurality of first through holes opened in a prescribed first pattern, the second inorganic plate has a plurality of second through holes opened in a prescribed second pattern, the casing forms an inner rib which projects from an inner surface of the opening, the inner rib is interposed between the first inorganic plate and the second inorganic plate to form the second gap d2, and positions the first inorganic plate and the second inorganic plate in such a way that the second through holes are positionally displaced from the first through holes, such that the interior of the casing cannot be viewed from the outside.

Description

[Technical Field]

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

[0002] Battery packs, which consist of multiple secondary battery cells connected in series and parallel, are used as power sources for portable electric devices such as electric cleaners and power tools; as stationary power storage devices for server backup power supplies; and as power sources for home, office, and factory use. They are also used as driving power sources for assisted bicycles, electric scooters, electric carts, and vehicles such as hybrid and electric vehicles. Lithium-ion secondary batteries are generally used as secondary battery cells in such battery packs. However, lithium-ion secondary batteries can be subject to unsafe conditions, such as the emission of smoke or fire, due to an abnormality such as bolt penetration during a collision. If an unsafe condition were to occur in a battery pack, there is a risk that the fire from the internal secondary battery cells could be released outside the battery pack.

[0003] To prevent this, it is necessary to prevent flames from leaking outside even if an abnormality occurs in the battery pack. Conventionally, a countermeasure has been taken by wrapping fire-resistant fibers around the core pack of the secondary battery cells. However, in small battery packs with outer casings below a certain size, the pack is unable to absorb the gas pressure emitted from the cells, resulting in the problem of flames leaking outside the battery pack. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2020 / 153017 issue Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a battery pack that prevents flames from leaking to the outside in the event of an abnormality.

[0006] In order to achieve the above-mentioned object, a battery pack according to a first embodiment of the present invention comprises: a battery holder having a plurality of secondary battery cells, each having a safety valve; a housing having an opening surface with at least one side partially open, which houses the battery holder; a first inorganic plate arranged in the opening of the housing, spaced apart from the battery holder to form a first gap between it and the surface of the battery holder; and a second inorganic plate arranged in the opening of the housing, spaced apart from the first inorganic plate to form a second gap between it and the first inorganic plate, wherein the first inorganic plate has a plurality of first through holes formed in a predetermined first pattern, and the second inorganic plate has a plurality of second through holes formed in a predetermined second pattern, and the housing forms an inner rib protruding from the inner surface of the opening, and the inner rib is interposed between the first inorganic plate and the second inorganic plate to form the second gap, and the first inorganic plate and the second inorganic plate are positioned so that the second through holes are misaligned with the first through holes so that the inside of the housing cannot be seen from the outside through the second through holes. With the above configuration, a second gap is formed between the first inorganic plate and the second inorganic plate using the inner rib of the housing, and these are positioned in the thickness direction while also being positioned in the planar direction so that the first through hole and the second through hole do not overlap.By doing so, even if the secondary battery cell were to open the safety valve due to some abnormality and cause a flame to form, the momentum is weakened and heat is removed by creating paths with different traveling directions from the first gap to the first through hole, from the first through hole to the second gap, and from the second gap to the second through hole, thereby preventing the flame generated from the secondary battery cell from being directly released outside the battery pack and improving safety.

[0007] In a battery pack according to a second aspect of the present invention, the inner rib has a first step portion on a surface facing the battery holder and a second step portion on the opposite surface, the first step portion abutting against an end surface of the first inorganic plate to position the first inorganic plate in a plane parallel to the opening surface, and the second step portion abutting against an end surface of the second inorganic plate to position the second inorganic plate in a plane parallel to the opening surface. With this configuration, the first inorganic plate and the second inorganic plate can be easily positioned in the planar direction of the opening surface by the inner rib of the housing, and the first through hole and the second through hole can be offset to bend the flame propagation path and ensure the suppression effect.

[0008] Furthermore, in any one of the above configurations, the battery pack according to a third embodiment of the present invention is such that the second step portion is formed so as to be misaligned with the first step portion within the opening surface.

[0009] Furthermore, in a battery pack according to a fourth aspect of the present invention, in any of the above configurations, the second step portion is formed so as to be shifted relative to the first step portion within the opening surface by a first displacement amount in a first direction and a second displacement amount in a second direction perpendicular to the first direction.

[0010] Furthermore, in a battery pack according to a fifth embodiment of the present invention, in any one of the above configurations, the first displacement amount and the second displacement amount are set equal to each other.

[0011] Furthermore, in a battery pack according to a sixth aspect of the present invention, in any of the above configurations, the battery holder has a plurality of protrusions at an edge of the opening that protrude from a surface of the battery holder toward the inner rib of the housing, and the end faces of the plurality of protrusions abut against an edge of one surface of the first inorganic plate to form the first gap between the surface of the battery holder and the first inorganic plate, and the end faces of the protrusions face the inner rib to form a first holding space that holds the edge of the first inorganic plate. With the above configuration, the inner rib and the protrusions make it easy to position the first inorganic plate in the thickness direction.

[0012] Furthermore, in a battery pack according to a seventh aspect of the present invention, in any of the above configurations, the multiple protrusions protrude in a direction opposite to the opening surface of the housing and are formed in lines extending in a parallel state along the top and bottom of the opening.

[0013] Furthermore, in a battery pack according to an eighth aspect of the present invention, in any of the above configurations, the second inorganic plate is made of the same material as the first inorganic plate. With this configuration, by arranging the same inorganic plates, each having a large number of through holes formed in a predetermined pattern, in a staggered manner, a configuration that exhibits an extinguishing effect can be realized, and cost reduction and workability during assembly can be improved by standardizing the materials.

[0014] Furthermore, in a battery pack according to a ninth aspect of the present invention, in any of the above configurations, the first inorganic plate has a plurality of first fixing holes for fixing to the housing, and the second inorganic plate has a plurality of second fixing holes for fixing to the housing, the first inorganic plate and the second inorganic plate are fixed to the housing by passing fasteners through the first fixing holes and the second fixing holes, and the first fixing holes are positioned so that when the first inorganic plate is rotated 180 degrees, the first fixing holes of the first inorganic plate coincide with the position of the second fixing holes of the second inorganic plate. With the above configuration, the first inorganic plate and the second inorganic plate are positioned with a misalignment within the opening surface so that the first through hole and the second through hole do not overlap, while the first fixing hole and the second fixing hole must be opened in an overlapping position so that a fastener such as a screw or pin can be passed through the first inorganic plate and the second inorganic plate when they are stacked, and therefore a common inorganic plate cannot be used.However, by previously positioning the first through hole so that it coincides with the second through hole when the first inorganic plate is inverted so that it can be used as the second inorganic plate when inverted, it is possible to use a common inorganic plate and position the first through hole and the second through hole so that they are misaligned while the first fixing hole and the second fixing hole are aligned.

[0015] Furthermore, in a battery pack according to a tenth aspect of the present invention, in any of the above configurations, opposing main surfaces of the casing are the opening surfaces, and the first inorganic plate and the second inorganic plate are respectively arranged on each opening surface. With this configuration, when the safety valve opens, gas is discharged from both sides of the battery pack, thereby ensuring the gas discharge capacity per unit time and preventing the inside of the battery pack from becoming high pressure.

[0016] Furthermore, in a battery pack according to an eleventh embodiment of the present invention, in any of the above configurations, the distance between the first through holes and the second through holes is between two and ten times the inner diameter of the through holes.

[0017] Furthermore, in a battery pack according to a twelfth embodiment of the present invention, in any one of the above configurations, the first through hole and the second through hole have a diameter of 0.5 mmφ to 2 mmφ.

[0018] Furthermore, in a battery pack according to a thirteenth aspect of the present invention, in any one of the above configurations, the first inorganic plate and the second inorganic plate are made of metal plates. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing a battery pack according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the battery pack of FIG. 1. [Figure 3] FIG. 3 is an exploded perspective view of the battery holder of FIG. 2. [Figure 4] 4 is a cross-sectional view of the battery pack taken along line IV-IV in FIG. 1. [Figure 5] 2 is a cross-sectional view of the battery pack taken along line VV in FIG. 1. [Figure 6] 6 is a cross-sectional perspective view of the battery pack of FIG. 1 taken along line VI-VI. DETAILED DESCRIPTION OF THE INVENTION

[0020] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to these. Furthermore, this specification in no way specifies the components set forth in the claims as components of the embodiments. The dimensions, materials, shapes, and relative positions of components described in the embodiments are not intended to limit the scope of the present invention, and are merely illustrative unless otherwise specified. The size and relative positions of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present invention may be configured with the same components, so that one component serves multiple functions, or conversely, the function of one component may be shared by multiple components.

[0021] The battery pack of the present invention can be used as a power source for portable electric devices such as electric cleaners and power tools, or as a backup power source for servers in stationary power storage applications, or as a power source for homes, offices, and factories, and further as a power source for driving electric-powered bicycles, electric scooters, electric carts, or vehicles such as hybrid cars and electric automobiles. Hereinafter, a battery pack used as a power source for portable electric devices will be described as one embodiment of the present invention. [Embodiment 1]

[0022] A battery pack 100 according to a first embodiment of the present invention is shown in an external perspective view in FIG. 1 and an exploded perspective view in FIG. 2. The battery pack 100 shown in these figures includes a battery holder 10, a housing 20, a first inorganic plate 30, and a second inorganic plate 40. The housing 20 houses the battery holder 10 therein. The housing 20 also has at least one partially open opening. In the example shown in FIG. 2, two opposing sides of the housing 20, i.e., the left and right sides of the box-shaped housing 20 in the figure, are open. A first inorganic plate 30 and a second inorganic plate 40 are stacked on top of each other on each open side. The first inorganic plate 30 and the second inorganic plate 40 are fixed to the housing 20 by a fastener 50. The first inorganic plate 30 and the second inorganic plate 40 each have a first through hole 31 and a second through hole 41. The first through hole 31 and the second through hole 41 are offset from each other. In other words, the openings of the first through hole 31 and the second through hole 41 do not overlap, and the interior of the battery pack 100 cannot be seen from the outside through the second through hole 41. By arranging multiple inorganic plates on one side of the housing in this way and arranging the through holes in each inorganic plate so that they are offset from one another, it is possible to effectively prevent the flames from directly leaking out of the battery pack even if one of the secondary battery cells housed inside the battery pack catches fire. (Battery holder 10)

[0023] The battery holder 10 is formed with an outer shape slightly smaller than the inner shape of the housing 20 so that it can be housed inside the housing 20. It also has multiple protrusions 12 formed on its surface. Each protrusion 12 protrudes from the surface of the battery holder 10 toward the inner surface of the housing 20 when the battery holder 10 is housed in the housing 20. In the example shown in FIG. 2, a pair of protrusions 12 are formed parallel to each other along the upper and lower edges of the opening 22 of the housing 20. These protrusions 12 are formed integrally with the battery holder 10. Furthermore, a slit 14 is formed between the pair of protrusions 12.

[0024] An exploded perspective view of the battery holder 10 is shown in Figure 3. This battery holder 10 holds rechargeable battery cells 1 and a substrate 60. The battery holder 10, with the rechargeable battery cells 1 and substrate 60 set inside, forms a core pack. The substrate 60 is placed and fixed on one side of the battery holder 10. The battery holder 10 also holds multiple rechargeable battery cells 1. This battery holder 10 is divided into two sub-holders 11A and 11B, which hold multiple rechargeable battery cells 1 by sandwiching them lengthwise. Each of the sub-holders 11A and 11B forms a cylindrical storage space 13 that houses the rechargeable battery cells 1. In this example, four rechargeable battery cells 1 are stacked and held in a two-row x two-column configuration. The number and stacking method of the rechargeable battery cells are not limited to this configuration; three or fewer, or five or more, may be held. Furthermore, the number of layers is not limited to two; a single layer, in which all the rechargeable battery cells are arranged on the same plane, may be used, or three or more layers may be used. In addition to a matrix arrangement, the batteries may be arranged in a staggered pattern, with each level alternating. For example, the battery holder thickness can be reduced by creating two levels of storage space and offsetting the cylindrical centers of the upper and lower levels. The battery holder 10 is made of a material with excellent insulating and heat-resistant properties, such as polycarbonate ABC resin. (Secondary battery cell 1)

[0025] Each secondary battery cell 1 is a cylindrical secondary battery cell whose outer can is cylindrical. The cylindrical secondary battery cell has electrode surfaces on both end faces. One of the electrode surfaces is also equipped with a safety valve. The safety valve is a component that opens to release internal gas when the internal pressure of the outer can increases. Although the safety valve is generally provided on the positive electrode side, the present invention does not limit the location of the safety valve to the positive electrode side; it may be provided in another position, for example, on the negative electrode side. The battery holder 10 also has a slit 14 formed in it so that gas released from the safety valve can be released to the outside of the battery holder 10 when the safety valve opens.

[0026] Cylindrical lithium-ion secondary batteries are suitable for use as such secondary battery cells 1. However, the battery pack of the present invention does not limit the secondary battery cells to cylindrical batteries, nor does it limit them to lithium-ion secondary batteries. Any rechargeable battery, such as nickel-metal hydride batteries or nickel-cadmium batteries, can be used as the secondary battery cells. (reed plate)

[0027] Lead plates are fixed to the end faces of the secondary battery cells 1. Multiple secondary battery cells 1 are connected in series or parallel via the lead plates. The lead plates are made of metal plates and are welded to the secondary battery cells 1. Lead positioning guides that follow the outline of the lead plates are formed on the inner surface of the battery holder 10 to position the lead plates in a predetermined position. The lead plates may be placed on the outer surface of the battery holder rather than the inner surface. In this case, after the secondary battery cells are inserted into the storage space of the battery holder, the lead plates are fixed to the electrode surfaces of the secondary battery cells that are exposed from the battery holder. The output of the core pack, which is made up of secondary battery cells 1 connected in series or parallel via lead plates in this way, is output from the battery pack 100.

[0028] Furthermore, the upper surface of the battery holder 10 serves as a mounting surface 15 on which a substrate 60 is placed. A frame for holding the substrate 60 may be formed on the mounting surface 15. Alternatively, a substrate holder for holding the substrate may be provided separately. (Substrate 60)

[0029] Electronic circuits such as a voltage detection circuit that detects the total potential and intermediate potential of the battery assembly in which the secondary battery cells 1 are connected in series or parallel, a control circuit that controls charging and discharging, and a safety circuit are mounted on the substrate 60. The substrate 60 is formed in a rectangular shape. (Housing 20)

[0030] The housing 20 that houses the battery holder 10 is box-shaped. In the example shown in Figure 1, the housing 20 is divided into two sub-cases 21A and 21B, which house the battery holder 10 by sandwiching it from the left and right. The direction in which the sub-cases 21A and 21B are separated is 90° to the direction in which the battery holder 10 is separated into sub-holders 11A and 11B, which increases resistance to impact. Each sub-case 21A and 21B is made of a material with excellent insulating properties, such as a resin such as polycarbonate or ABS. (Inner rib 23)

[0031] The housing 20 also has openings on opposing side surfaces (left and right in FIG. 1). An inner rib 23 is provided on the inner surface of the opening. A first inorganic plate 30 and a second inorganic plate 40 are further disposed on the opening. The first inorganic plate 30 and the second inorganic plate 40 are stacked with the inner rib 23 sandwiched between them, as shown in the cross-sectional views of FIG. 4 and FIG. 5 and the cross-sectional perspective view of FIG. 6. As a result, a second gap d2 having a thickness equivalent to the thickness of the inner rib 23 is formed between the first inorganic plate 30 and the second inorganic plate 40. (Protrusion 12)

[0032] Meanwhile, as described above, multiple protrusions 12 are formed on the surface of the battery holder 10. Each protrusion 12 protrudes toward an inner rib 23 provided on the edge of the opening 22 of the housing 20, and the end face of the protrusion 12 and the inner rib 23 sandwich and hold the edge of the first inorganic plate 30. Furthermore, as shown in Figures 4 and 6, a first gap d1 corresponding to the height of the protrusions 12 is formed between the surface of the battery holder 10 and the first inorganic plate 30.

[0033] In this way, the first inorganic plate 30 is disposed on the inner surface side of the inner rib 23, and the second inorganic plate 40 is disposed on the outer surface side, and the relative positions of the first inorganic plate 30 and the second inorganic plate 40 in the thickness direction are determined by the inner rib 23. Furthermore, the relative positions of the first inorganic plate 30 and the battery holder 10 in the thickness direction are determined by the protrusion 12. (First inorganic plate 30)

[0034] The first inorganic plate 30 and the second inorganic plate 40 are disposed in the opening 22 of the housing 20. The first inorganic plate 30 is separated from the battery holder 10 by a protrusion 12. A first gap d1 is provided between the surface of the battery holder 10 and the first inorganic plate 30. The first inorganic plate 30 has a large number of first through holes 31 formed in a predetermined first pattern. The first through holes 31 are preferably circular. However, they may also be polygonal, such as hexagonal or octagonal. In the example shown in FIG. 1, the predetermined first pattern is a matrix. Here, adjacent first through holes 31 are spaced approximately equally apart vertically and horizontally. The first inorganic plate 30 can be made of a material with sufficient strength and heat resistance, such as a metal plate such as aluminum or a plate made of a mineral material such as mica. From the perspectives of thermal conductivity, durability, ease of processing, and the like, it is preferable to form the first inorganic plate 30 and the second inorganic plate 40 from metal plates.

[0035] The first through holes 31 must have a certain opening area to reduce the force of high-temperature, high-pressure gas and flames that are released when the safety valve of the secondary battery cell 1 is opened, preventing them from being suddenly released directly to the outside of the battery pack 100. This reduces the temperature and prevents the pressure inside the battery pack 100 from building up, which could lead to a rupture. However, increasing the opening area of ​​each first through hole 31 makes the flame more likely to leak. Therefore, by increasing the number of first through holes 31 while keeping the opening area of ​​each first through hole 31 small, the total opening area is increased, ensuring the amount of gas discharged per unit time while preventing the sudden release of high-temperature, high-pressure gas and flames. In the example shown in FIG. 1 , the inner diameter of each first through hole 31 is 0.5 mm to 2 mm, preferably approximately 1 mm. Furthermore, the longitudinal (i.e., vertical) spacing WDy between the first through holes 31 is preferably between two and ten times the inner diameter of the through hole. In this way, by lengthening the distance between the first through holes 31, it becomes easier to arrange the second through holes 41 therebetween. (Second inorganic plate 40)

[0036] The second inorganic plate 40 is separated from the first inorganic plate 30 by an inner rib 23. By interposing the inner rib 23 between the second inorganic plate 40 and the first inorganic plate 30, a second gap d2 is formed therebetween. The second inorganic plate 40 also has a large number of second through holes 41 formed in a predetermined second pattern. Like the first through holes 31, the second through holes 41 are preferably circular. The predetermined second pattern is also a matrix. The second inorganic plate 40 may be formed separately from the first inorganic plate 30, but preferably the same material is used. This provides the advantage of sharing parts, reducing manufacturing costs, and improving workability during assembly.

[0037] The first through hole 31 of the first inorganic plate 30 and the second through hole 41 of the second inorganic plate 40 are misaligned so that their opening areas do not overlap. Therefore, the inner rib 23 positions the first inorganic plate 30 and the second inorganic plate 40 so that the first through hole 31 and the second through hole 41 are misaligned. In the enlarged cross-sectional view of a main portion shown in FIG. 4 , the section is taken along the position of the second through hole 41, and the first through hole 31 is indicated by a dashed line. Conversely, in the enlarged perspective cross-sectional view of a main portion shown in FIG. 5 , the section is taken along the position of the first through hole 31, and the second through hole 41 is indicated by a dashed line. As shown in these figures, the inner rib 23 of the housing 20 forms a second gap d2 between the first inorganic plate 30 and the second inorganic plate 40, positioning them in the thickness direction and also positioning them so that the first through hole 31 and the second through hole 41 do not overlap in the planar direction. This prevents flames from leaking to the outside even if the safety valve of the secondary battery cell 1 opens due to some abnormality. That is, the flame or high-pressure gas that moves from the first gap d1 through the first through-hole 31 to the second gap d2 is prevented from escaping by the second inorganic plate 40 and is forced to bend its path instead of escaping to the outside. That is, by forming a different path—moving from the first gap d1 through the first through-hole 31 to the second gap d2, then to another position in the second gap d2, and then passing through the second through-hole 41—the flame or high-pressure gas is weakened and heat is absorbed, preventing the flame from the secondary battery cell 1 from directly escaping to the outside of the battery pack 100 and improving safety. Furthermore, the second inorganic plate 40 has superior strength and thermal conductivity compared to a plate material made of resin, and therefore can block the flame or high-pressure gas that has just passed through the first through-hole 31. Furthermore, by using a metal for the first inorganic plate 30, the high heat capacity and thermal conductivity of the first inorganic plate 30 and the second inorganic plate 40 can contribute to lowering the temperature of the flame or high-pressure gas.

[0038] To offset the first through hole 31 and the second through hole 41 in this manner, the internal rib forms a first step 24 on the surface facing the battery holder 10 and a second step 25 on the opposite surface, as shown in the enlarged view of a main portion in FIG. 4 . The first step 24, together with the end face of the protrusion 12, forms a first holding space that holds the edge of the first inorganic plate 30. By abutting the first step 24 against the end face of the first inorganic plate 30, the edge of the first inorganic plate 30 is held in the first holding space, and the first inorganic plate 30 is positioned in a plane parallel to the opening surface. Furthermore, by abutting the second step 25 against the end face of the second inorganic plate 40, the second inorganic plate 40 is positioned in a plane parallel to the opening surface. In this way, the internal rib 23 of the housing 20 can easily position the first inorganic plate 30 and the second inorganic plate 40 in the planar direction of the opening surface.

[0039] The second step portion 25 is formed to be misaligned with the first step portion 24 within the opening plane. Specifically, the second step portion 25 is displaced by a first displacement amount in a first direction relative to the first step portion 24. The first direction is, for example, the up-down direction or the Y direction. In the example of FIG. 4 , as shown in the enlarged view of a main portion thereof, the second step portion 25 is positioned above the first step portion 24 by the first displacement amount Dy. In this example, the vertical spacing WDy between the first through holes 31 is set equal to the vertical spacing WDy between the second through holes 41. Under this condition, the first displacement amount Dy is preferably set to ½ of the vertical spacing WDy between the first through holes 31. This positions the second through holes 41 midway between the first through holes 31, maximizing the distance between the first through holes 31 and the second through holes 41. This increases the travel distance of the high-pressure gas and flame discharged from the safety valve, thereby contributing to weakening their momentum and lowering their temperature.

[0040] Furthermore, it is preferable that the second step portion 25 be displaced not only in the first direction but also in a second direction perpendicular to the first direction. The second direction may be, for example, the left-right direction or the X direction. In the horizontal cross-sectional view of FIG. 5, as shown in the enlarged view of a main portion thereof, the second step portion 25 is disposed horizontally (to the left in the drawing) by a second displacement amount Dx relative to the first step portion 24. In this example, the lateral, i.e., horizontal, spacing WDx between the first through holes 31 is set equal to the horizontal spacing WDx between the second through holes 41. Under this condition, it is preferable that the second displacement amount Dx is set equal to 1 / 2 of the horizontal spacing WDx between the second through holes 41. More preferably, the second displacement amount Dx is set equal to the first displacement amount Dy. In particular, by matching the first pattern having the first through holes 31 with the second pattern having the second through holes 41, and further making the vertical and horizontal spacings WDx and WDy between adjacent first through holes 31 and second through holes 41 equal, the vertical and horizontal spacings of the first through holes 31 and the second through holes 41 become equal, which prevents high-pressure gas, etc. from concentrating in a few through holes when it is discharged, and allows the high-pressure gas, etc. to be discharged by dispersing it evenly so that it is close to the gas, thereby increasing discharge efficiency and improving safety. (fixture 50)

[0041] The first inorganic plate 30 and the second inorganic plate 40 are fixed to the housing 20 by fasteners 50. Housing fastening holes 26 are formed in the housing 20, through which the fasteners 50 are inserted. In the example of FIG. 2, the housing fastening holes 26 are formed in the inner rib 23. The fasteners 50 can be screws, bolts, rivets, or the like. The first inorganic plate 30 has a plurality of first fastening holes 32 formed therein for fastening to the housing 20. In the example of FIG. 2, the first fastening holes 32 are formed in each of the four corners of the first inorganic plate 30. Similarly, the second inorganic plate 40 has a plurality of second fastening holes 42 formed therein for fastening to the housing 20. In the example of FIG. 2, the second inorganic plate 40 has a plurality of second fastening holes 42 formed therein for similarly ... The first inorganic plate 30 and the second inorganic plate 40 are fixed to the housing 20 by passing fasteners 50 through the first fastening holes 32 and the second fastening holes 42.

[0042] As described above, the first inorganic plate 30 and the second inorganic plate 40 need to be fixed with the first through hole 31 and the second through hole 41 misaligned. On the other hand, if the first inorganic plate 30 and the second inorganic plate 40 are fixed using a common fixture 50 rather than being fixed individually, the first fixing hole 32 and the second fixing hole 42 need to be aligned when the first inorganic plate 30 and the second inorganic plate 40 are stacked in a spaced apart position. When the first inorganic plate 30 and the second inorganic plate 40 are individually designed, it is sufficient to open through holes and fixing holes in the necessary locations. On the other hand, when the first inorganic plate 30 and the second inorganic plate 40 are constructed using a common inorganic plate, the first fixing hole 32 and the second fixing hole 42 need to be aligned while the first inorganic plate 30 and the second inorganic plate 40 are misaligned. Therefore, the fixing holes are not provided in symmetrical positions relative to the plane of the inorganic plate, but are provided in positions that match when the plate is inverted. In the example shown in FIG. 2 , the second inorganic plate 40 is rotated 180° relative to the horizontally elongated rectangular first inorganic plate 30. Instead of rotating the first inorganic plate 30 by 180°, the first fixing holes of the first inorganic plate may be positioned so that they coincide with the positions of the second fixing holes of the second inorganic plate by combining inversion and rotation. Alternatively, if the first inorganic plate is square, the first fixing holes may be positioned so that they coincide with the positions of the second fixing holes of the second inorganic plate by rotating the first inorganic plate by 90°. In this way, by aligning the positions of the first fixing holes 32 with the positions of the second fixing holes 42 by rotating or inverting the first inorganic plate rather than providing the first fixing holes 32 evenly at the four corners or in line-symmetric or point-symmetric positions, it is possible to align the fixing holes while maintaining misalignment between the through holes and the second through holes 41 using a common inorganic plate. Using a common inorganic plate is advantageous in terms of raw material costs and ease of assembly. [Industrial Applicability]

[0043] The battery pack according to the present invention can be suitably used as a power source for portable electrical devices such as electric cleaners and power tools, and can also be suitably used as a power source device for mobile objects such as assisted bicycles and electric carts. [Explanation of symbols]

[0044] 100...Battery pack 1... Secondary battery cell 10...Battery holder 11A, 11B...Sub holder 12...Protrusion 13...Storage space 14...Slit 15...Placement surface 20…Housing 21A, 21B...Subcase 22…Aperture 23...Inner rib 24...First step part 25...Second step part 26...Housing fixing hole 30...First inorganic plate 31...First through hole 32...First fixing hole 40...Second inorganic plate 41...Second through hole 42...Second fixing hole 50…Fixing tool 60...Substrate d1...first gap d2...second gap WDy: Vertical distance between through holes WDx: Horizontal distance between through holes Dy...First displacement amount Dx: Second displacement

Claims

1. a battery holder having a plurality of secondary battery cells each having a safety valve; a housing having an opening surface with at least one surface partially open, the housing housing housing the battery holder; a first inorganic plate that is disposed in the opening of the housing and is spaced apart from the battery holder with a first gap formed between the first inorganic plate and a surface of the battery holder; a second inorganic plate that is disposed in the opening of the housing and is spaced apart from the first inorganic plate with a second gap formed between the first inorganic plate and the second inorganic plate; A battery pack comprising: the first inorganic plate has a plurality of first through holes formed in a predetermined first pattern; the second inorganic plate has a plurality of second through holes formed in a predetermined second pattern; The housing has an inner rib that protrudes from the inner surface of the opening, A battery pack in which the inner rib is interposed between the first inorganic plate and the second inorganic plate to form the second gap, and the first inorganic plate and the second inorganic plate are positioned so that the second through hole is misaligned with the first through hole so that the inside of the housing cannot be seen from the outside through the second through hole.

2. 2. The battery pack according to claim 1, The inner rib is a first step portion is formed on a surface facing the battery holder, and a second step portion is formed on the opposite surface, the first step portion is brought into contact with an end surface of the first inorganic plate, and the first inorganic plate is positioned in a plane parallel to the opening surface; The battery pack has the second step portion abutting against an end surface of the second inorganic plate, thereby positioning the second inorganic plate in a plane parallel to the opening surface.

3. 3. The battery pack according to claim 2, The second step portion is formed in the opening plane so as to be offset from the first step portion.

4. The battery pack according to claim 3, The second step portion is formed within the opening surface so as to be displaced relative to the first step portion by a first displacement amount in a first direction and a second displacement amount in a second direction perpendicular to the first direction.

5. 5. The battery pack according to claim 4, The battery pack has the first displacement amount and the second displacement amount set equal to each other.

6. The battery pack according to any one of claims 1 to 5, the battery holder has a plurality of protrusions at an edge of the opening that protrude from a surface of the battery holder toward the inner rib of the housing, The battery pack has the end faces of the multiple protrusions abutting against the edge of one side of the first inorganic plate to form the first gap between the surface of the battery holder and the first inorganic plate, and the end faces of the protrusions facing the inner rib to form a first holding space that holds the edge of the first inorganic plate.

7. 7. The battery pack according to claim 6, The battery pack has a plurality of protrusions that protrude in a direction facing the opening surface of the housing and are formed in linear shapes that extend parallel to each other along the top and bottom of the opening.

8. The battery pack according to any one of claims 1 to 7, The battery pack is configured such that the second inorganic plate is made of the same material as the first inorganic plate.

9. 9. The battery pack according to claim 8, the first inorganic plate has a plurality of first fixing holes formed therein for fixing to the housing; the second inorganic plate has a plurality of second fixing holes formed therein for fixing to the housing; the first inorganic plate and the second inorganic plate are fixed to the housing by passing fasteners through the first fixing holes and the second fixing holes, A battery pack in which the first fixing hole of the first inorganic plate is positioned so that when the first inorganic plate is rotated 180 degrees, the first fixing hole of the first inorganic plate coincides with the position of the second fixing hole of the second inorganic plate.

10. The battery pack according to any one of claims 1 to 9, The battery pack has opposing main surfaces of the housing as the opening surfaces, and the first inorganic plate and the second inorganic plate are disposed on each opening surface.

11. The battery pack according to any one of claims 1 to 10, The battery pack has a spacing between the first through holes and the second through holes that is between two and ten times the inner diameter of the through holes.

12. The battery pack according to any one of claims 1 to 11, The battery pack, wherein the first through hole and the second through hole have a diameter of 0.5 mm to 2 mm.

13. The battery pack according to any one of claims 1 to 12, The battery pack, wherein the first inorganic plate and the second inorganic plate are made of metal plates.

Images