Battery pack and method for manufacturing same

Abstract

The present invention suppresses the generation of bubbles in a configuration in which the interior of an outer case is filled with a potting material. An outer case 10 has a rectangular outer shape extending in a first direction in plan view, and has a case first main surface 11a where the inner surface of the outer case 10 faces a block first main surface 2a, and a case second main surface 12a where the inner surface of the outer case 10 faces a block second main surface 2b. Formed in the case first main surface 11a are: a filling hole 14, which is for filling an internal space with an uncured filler 50 between the inner surface of the outer case 10 and the surface of a battery block 2; and an air hole 15, which is formed spaced apart from the filling hole 14. The inner surface at the case first main surface 11a is formed in the shape of a bowl such that the distance between the inner surface at the case first main surface 11a and the surface of the block first main surface 2a is the largest in the region where the filling hole 14 is provided, and such that said distance decreases leading away from the filling hole 14 in the direction of the case first main surface 11a.

Description

Battery Pack and Method for Manufacturing the Same

[0001] The present disclosure relates to a battery pack and a method for manufacturing the same.

[0002] Battery packs configured with rechargeable secondary battery cells such as lithium-ion secondary batteries are housed inside an exterior case and used in various applications to drive electrical devices. In such battery packs, there are some cases where a potting material is filled inside the exterior case to fill gaps for purposes such as enhancing heat dissipation and explosion protection (for example, Patent Document 1).

[0003] However, it is not easy to evenly distribute the potting material in the gap between the inner surface of the exterior case and the surface of the battery block. In particular, many potting agents have a high viscosity. Also, in the case of a configuration where the exterior case is divided into upper and lower parts, since the inner surface of the upper case is flat, the potting material may diffuse irregularly and air bubbles may remain.

[0004] Japanese Unexamined Patent Application Publication No. 2011-113722

[0005] One problem of the present disclosure is to provide a battery pack and a method for manufacturing the same that can suppress the generation of air bubbles in a configuration where a potting material is filled inside an exterior case. Another problem is to provide a battery pack and a method for manufacturing the same that facilitate the removal of air bubbles on the inner surface of the main surface of the first case of the exterior case. Still another problem is to provide a battery pack and a method for manufacturing the same that have explosion protection. Note that the description of these objects and problems of the present disclosure does not prevent the existence of other objects and problems. Also, one aspect of the present disclosure does not need to solve all of these problems. Furthermore, other problems can be extracted from the description of the specification, drawings, and claims of the present disclosure.

[0006] A battery pack according to one embodiment of the present disclosure comprises one or more battery blocks, each having a first main surface and a second main surface of a block facing each other; an outer case for housing the battery blocks in an internal space; and a filler material filled between the inner surface of the outer case and the surface of the battery blocks in the internal space, wherein the outer case has an outer shape in plan view that is a rectangle extended in a first direction, and its inner surface has a first main surface of the case facing the first main surface of the block and a second main surface of the case facing the second main surface of the block, and a filling hole for filling the filler material in an uncured state between the inner surface of the outer case and the surface of the battery blocks in the internal space, and an air hole opened spaced apart from the filling hole, opening on the first main surface of the case, and the inner surface of the first main surface of the case is formed in a mortar shape such that the distance between the inner surface of the first main surface of the case and the surface of the first main surface of the block is greatest in the region where the filling hole is provided, and approaches as the distance moves away from the filling hole in the direction of the first main surface of the case.

[0007] Another method for manufacturing a battery pack comprises one or more battery blocks, each having an opposing first main surface and a second main surface; an outer case for housing the battery blocks in an internal space; and a filler material filled between the inner surface of the outer case and the surface of the battery blocks in the internal space, wherein the outer shape in plan view is formed in a rectangular shape extended in the first direction, and its inner surface has a first main surface of the case facing the first main surface of the block and a second main surface of the case facing the second main surface of the block. The process includes: housing the battery block in the internal space of the outer case; inserting an injection tube through a filling hole opened in the first main surface of the case, filling the internal space with the filler material in an uncured state through the injection tube; removing air bubbles contained in the uncured filler material guided between the inner surface of the first main surface of the case and the surface of the first main surface of the block through an air hole opened at a distance from the filling hole on the inner surface of the first main surface of the case, which is formed in a mortar shape with the filling hole as its apex; and curing the uncured filler material filled in the internal space.

[0008] According to one embodiment of the present disclosure, when filling the internal space with uncured filler material, residual air is more easily collected in the area where the filling holes are provided, thereby suppressing the situation in which air bubbles remain in the cured filler material.

[0009] This is a perspective view showing a battery pack according to Embodiment 1. This is an exploded perspective view of the battery pack in Figure 1. This is an exploded perspective view of the battery pack in Figure 2, viewed from below. This is a perspective view showing the core block in Figure 2. This is an exploded perspective view of Figure 4 with the substrate removed. This is an exploded perspective view of Figure 5 with the battery holder removed. This is an exploded perspective view of the battery block connector in Figure 6, viewed from below. This is a perspective view of the battery holder, viewed from diagonally below. This is a schematic perspective view showing the direction of movement of air and filler material inside the battery pack. This is a vertical cross-sectional view of the battery pack in Figure 1 along line X-X. This is a perspective view of the second case in Figure 2. This is a perspective view showing the direction of filling of the filler material inside the battery pack in Figure 1. This is a vertical cross-sectional view of the battery pack in Figure 1 along line XIII-XIII. This is a perspective view showing the first case in Figure 2. This is a perspective view of the first case in Figure 14, viewed from the back side. This is a vertical cross-sectional view of the first case in Figure 15 along line XVI-XVI. This is a vertical cross-sectional view of the first case in Figure 15 along line XVII-XVII. This is an enlarged perspective view showing the opening rib in Figure 15.

[0010] The form of this disclosure may be specified by the following configurations and features.

[0011] In other embodiments of the present disclosure, the battery pack is formed such that the distance between the inner surface of the first main surface of the case and the surface of the first main surface of the block is minimized at the four corners of the outer case on the inner surface of the first main surface of the case.

[0012] Furthermore, in other embodiments of the present disclosure, the battery pack has multiple air holes opening so as to sandwich the filling hole. With this configuration, multiple air holes can be opened to effectively suppress the generation of air bubbles.

[0013] Furthermore, in any of the above embodiments of the battery pack, the inner surface of the first main surface of the case is formed in an isosceles trapezoidal shape with the region where the filling holes are provided as the upper edge when viewed in cross-section along the first direction, and the air holes are opened on the slanted sides of the isosceles trapezoidal shape. With the above configuration, by making the inner surface of the first main surface an isosceles trapezoidal shape in cross-section along the first direction, when filling the internal space with uncured filler material, residual air is guided along the slanted sides, making it easier for air to escape through the air holes opened on the slanted sides, thereby suppressing the situation in which air bubbles remain in the cured filler material.

[0014] Furthermore, in other embodiments of the present disclosure, the inner surface of the first main surface of the case is formed in an isosceles trapezoidal shape with the region where the filling holes are provided as the upper edge, in a cross-sectional view along a second direction intersecting the first direction. With this configuration, by making the inner surface mortar-shaped, when filling the internal space with uncured filler material, residual air is guided along the inclined surface and can easily escape through the air holes, thereby suppressing the situation in which air bubbles remain in the cured filler material.

[0015] Furthermore, in any of the above embodiments, the battery pack has a filling hole that is opened midway between the first direction and the second direction intersecting the first direction. This configuration ensures uniform filling by making the distance the filler material travels within the outer casing equal even in the short direction.

[0016] Furthermore, in other embodiments of the present disclosure, the battery pack in any of the above embodiments is provided with an opening rib that protrudes along the opening edge on the inner surface of the first main surface of the case. With this configuration, the opening rib prevents the filler material from being discharged from the air hole, thereby gaining time before the filler material is discharged from the air hole, guiding air bubbles into the air hole for easier discharge, and preventing air bubbles from remaining.

[0017] Furthermore, in any of the above embodiments, a battery pack is provided on the inner surface of the second main surface of the case, with guide ribs to prevent the uncured filler material, which is filled between the inner surface of the second main surface of the case and the surface of the second main surface of the block through the filling holes, from being filled in a second direction intersecting the first direction. With this configuration, the uncured filler material filled in the outer case tends to fill more easily in the short direction than in the longitudinal direction, resulting in difficulty in spreading in the longitudinal direction and the generation of air bubbles. However, by using guide ribs to prevent the uncured filler material from advancing in the second direction, which is the shorter direction, it is made easier for it to fill in the longer first direction, thereby achieving uniform filling in the internal space and suppressing the generation of air bubbles.

[0018] Furthermore, in other embodiments of the present disclosure, the battery pack, in any of the above embodiments, is configured such that the guide ribs are formed as a pair of walls extending in the first direction on the inner surface of the second main surface of the case, sandwiching a region corresponding to the filling hole. With this configuration, the wall-shaped guide ribs extending in the first direction block the progress of the uncured filler in the second direction intersecting the first direction, thereby making it relatively easier for the filler to progress in the first direction and promoting the filling of the uncured filler in the longitudinal direction.

[0019] Furthermore, in other embodiments of the present disclosure, the battery pack is configured such that the guide ribs are formed such that the width of the pair of wall-like structures widens as they move away from the region corresponding to the filling hole in the first direction. With this configuration, the guide ribs prevent the fast-moving, uncured filler material that has just been supplied into the internal space from the filling hole from spreading in the second direction by narrowing them from both sides, while widening them towards the first direction to reduce resistance and facilitate the diffusion of the filler material.

[0020] Furthermore, in other embodiments of the present disclosure, the battery pack in any of the above embodiments has the guide ribs extending radially from the region corresponding to the filling hole toward the rectangular corner of the second main surface of the case. With this configuration, the filler is guided in the first direction, and the flared guide ribs further guide the uncured filler guided in the first direction toward the corners where short circuits in the filler filling are likely to occur and create air pockets, thereby making it easier to fill the four corners of the second main surface of the case and suppressing the formation of air pockets and bubbles.

[0021] Furthermore, in other embodiments of the present disclosure, the battery pack is configured such that the guide rib is integrally formed with the second main surface of the case. This configuration allows the guide rib to be easily formed on the second main surface of the case.

[0022] Furthermore, in any of the above embodiments, the battery pack is divided into a first case and a second case, wherein the first case has a first main surface and the second case has a second main surface.

[0023] Furthermore, in any of the above embodiments, the battery pack is a silicone resin or a urethane resin.

[0024] Furthermore, in other embodiments of the present disclosure, in any of the above embodiments, one or more battery blocks have block walls formed on their sides along the first direction, and the block walls have notches formed in areas facing the corners of the outer casing. With this configuration, when the uncured filler material filled between the second main surface of the outer casing and the second main surface of the block gradually rises in level and reaches the first main surface of the case and the first main surface of the block, it flows in all at once from the sides of the battery block towards the center, thereby suppressing the situation in which the filler materials advancing from both sides mix in the center and are prone to generating air bubbles. In other words, by blocking the filler material that is trying to advance in the shorter direction, where the distance of advancement of the filler material is relatively short, with the block walls, and guiding the filler material to the first main surface of the case through the notches formed near the corners of the outer casing, the distance of advancement of the filler material is increased, and the filler material is gradually mixed, thereby suppressing the generation of air bubbles.

[0025] Furthermore, in any of the above embodiments, the battery packs relating to other embodiments of the present disclosure include, in any of the above embodiments, the one or more battery blocks communicating with the filling hole and forming a communication opening for guiding the uncured filler material between the inner surface of the second main surface of the case and the surface of the second main surface of the block through the filling hole.

[0026] Furthermore, in any other embodiment of the present disclosure, the battery pack comprises one or more battery blocks, and the communication port is formed between the two battery blocks.

[0027] The embodiments of this disclosure will be described below with reference to the drawings. However, the embodiments shown below are examples for concretizing the technical concept of this disclosure, and this disclosure is not limited to the following. Furthermore, this specification does not limit the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of this disclosure to those, unless otherwise specifically stated, but are merely illustrative examples. Note that the size and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and reference numeral indicate the same or similar members, and detailed explanations will be omitted as appropriate. Furthermore, each element constituting this disclosure may be configured such that multiple elements are made of the same member, with one member serving multiple elements, or conversely, the function of one member may be shared among multiple members.

[0028] The battery pack disclosed herein can be used as a power source for portable electrical equipment such as wireless devices, electric vacuums, and power tools; as a power source for mobile devices such as electric carts, electric scooters, and electric assist bicycles; or as a backup power source for servers, or as a power supply for homes, offices, and factories in stationary energy storage applications; and even as a power source for vehicles such as hybrid cars and electric vehicles. Hereinafter, one embodiment of the present invention will be described as a battery pack used as a power source for a transceiver. [Embodiment 1]

[0029] Figures 1 to 18 show a battery pack 100 according to Embodiment 1 of the present disclosure. In these figures, Figure 1 is a perspective view showing the battery pack 100 according to Embodiment 1, Figure 2 is an exploded perspective view of the battery pack 100 of Figure 1, Figure 3 is an exploded perspective view of the battery pack 100 of Figure 2 viewed from below, Figure 4 is a perspective view showing the core block 4 of Figure 2, Figure 5 is an exploded perspective view of Figure 4 with the substrate removed, Figure 6 is an exploded perspective view of Figure 5 with the battery holder 20 removed, Figure 7 is an exploded perspective view of the battery block connector 3 of Figure 6 viewed from below, Figure 8 is a perspective view of the battery holder 20 viewed from diagonally below, Figure 9 is a schematic perspective view showing the direction of movement of air and filler 50 inside the battery pack 100, and Figure 10 shows the X-axis of the battery pack 100 of Figure 1. Figure 11 is a perspective view of the second case 12 in Figure 2, Figure 12 is a perspective view showing the filling direction of the filler material 50 inside the battery pack 100 in Figure 1, Figure 13 is a vertical cross-sectional view of the battery pack 100 in Figure 1 in the XIII-XIII direction, Figure 14 is a perspective view showing the first case 11 in Figure 2, Figure 15 is a perspective view of the first case 11 in Figure 14 viewed from the back side, Figure 16 is a vertical cross-sectional view of the first case 11 in Figure 15 in the XVI-XVI direction, Figure 17 is a vertical cross-sectional view of the first case 11 in Figure 15 in the XVII-XVII direction, and Figure 18 is an enlarged perspective view showing the opening rib 16 in Figure 15. The battery pack 100 shown in these figures comprises an outer case 10 and a core block 4. (Outer case 10)

[0030] The outer casing 10 houses the core block 4. The outer shape of the outer casing 10 can be any shape with an internal space inside. In the examples shown in Figures 1 to 3, the outer casing 10 is formed in a box shape with its exterior extended in the first direction. The box-shaped outer casing 10 is divided into a first case 11 and a second case 12, which are divided vertically or horizontally. This outer casing 10 is preferably made of a material with excellent insulating properties, such as a resin such as polycarbonate or PC-ABS alloy. It may also be made of a metal material such as aluminum or its alloy. An internal space for housing the core block 4 is defined inside the box shape.

[0031] Furthermore, the outer casing 10 has a first main surface 11a facing the first main surface 2a of the battery block 2, and a second main surface 12a facing the second main surface 2b of the battery block 2. In the example shown in Figure 2, the first case 11 has the first main surface 11a, and the second case 12 has the second main surface 12a. In addition, the outer casing 10 has a filling hole 14 opening in the first main surface 11a of the outer casing 10 for filling the space between the inner surface of the outer casing 10 and the surface of the battery block 2 in an uncured state. (Core block 4)

[0032] As shown in Figures 2 and 3, the core block 4 is housed in the internal space of the outer case 10. In this state, the gap between the inner surface of the outer case 10 and the surface of the core block 4 in the internal space is filled with filler material 50 (see Figure 10).

[0033] The core block 4 is constructed by integrating multiple components as shown in Figures 4 to 6. Specifically, the core block 4 is composed of a battery holder 20, a circuit board 30, and a battery block connector 3. (Battery block connector 3)

[0034] The battery block connector 3 is constructed by connecting multiple battery blocks 2. An example of the battery block connector 3 is shown in Figure 7. Each battery block 2 is composed of one or more secondary battery cells 1. The battery blocks 2 are connected to each other via intermediate lead plates 40. In the examples in Figures 6 and 7, each battery block 2 is composed of one secondary battery cell 1. However, each battery block may be composed of two or more secondary battery cells. Also, in the examples in Figures 6 and 7, a rectangular secondary battery cell with a rectangular outer casing is used as the secondary battery cell 1, but it is not limited to this, and pouch-type secondary battery cells or cylindrical secondary battery cells may also be used. (Battery Block 2)

[0035] Each battery block 2 has a first main surface 2a, a second main surface 2b facing the first main surface 2a, and a block end surface 2c that intersects with the first and second main surfaces 2b. In the example shown in Figures 6 and 7, each battery block 2 is composed of a single rectangular secondary battery cell 1, so the block end surface 2c becomes the cell end surface of the secondary battery cell 1. Multiple battery blocks 2 are connected in a manner in which the block end surfaces 2c of each battery block 2 face each other. Furthermore, in the figures, the upper surface of each battery block 2 is the first main surface 2a, and the lower surface is the second main surface 2b. In the example shown in Figures 6 and 7, multiple battery blocks 2 are arranged in a line along the longitudinal direction of the battery block 2 and connected by an intermediate lead plate 40. Multiple secondary battery cells 1 are connected in series or parallel via the intermediate lead plate 40, etc. The number of series connections and parallel connections can be arbitrarily set according to the required specifications. In the examples shown in Figures 6 and 7, two secondary battery cells 1 are connected in series, but the configuration is not limited to this. Alternatively, the core block may be composed of multiple battery blocks, with each battery block containing multiple secondary battery cells. (Secondary battery cell 1)

[0036] Each secondary battery cell 1 can be a cylindrical or rectangular secondary battery cell. In the examples shown in Figures 6 and 7, rectangular secondary battery cells 1 are used arranged horizontally. The number and arrangement of secondary battery cells 1 are not limited to this example, and any number and arrangement can be used as appropriate. For example, cylindrical secondary battery cells may be arranged in a matrix. Each secondary battery cell 1 has positive and negative electrodes. The positive and negative electrodes are preferably provided on one end face of the secondary battery cell 1. Known secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries can be used as secondary battery cells 1 as appropriate. (Battery holder 20)

[0037] The battery holder 20 is a component for holding multiple battery blocks 2. The battery holder 20 may also include a mechanism for holding or positioning the intermediate lead plate 40. Furthermore, the battery holder 20 has a spacer portion 25 formed on a part of it. The spacer portion 25 is inserted between the opposing block end faces 2c of the multiple battery blocks 2. By forming a spacer portion 25 that defines a guide path on a part of the battery holder 20 in this way, the structure can be simplified without increasing the number of parts. Preferably, the spacer portion 25 is integrally formed in the battery holder 20. However, the battery holder may be constructed by dividing it into multiple sub-holders. The battery holder 20 can also be made of a resin such as polycarbonate.

[0038] The battery holder 20 shown in Figure 8 has an open bottom surface to define a storage space for housing the battery block 2. Therefore, the battery holder 20 comprises a plate-shaped top plate 21, side walls 22 extending in the longitudinal direction of the top plate 21, a pair of end walls 23 formed on the longitudinal end faces, and a partition wall 24 parallel to the end walls 23 that demarcates the battery block 2. Output terminals and the like are arranged on the end walls 23. Furthermore, an opening window may be formed on one end face of the outer casing 10 to expose the output terminals from the outer casing 10.

[0039] The side wall 22 is approximately the same length as the top plate 21 and is positioned to intersect with the top plate 21 along its side surface. The battery holder 20 shown in Figure 8 has a side wall 22 on only one side, leaving the other side open. The side wall 22 covers the side surface of the battery block 2 and also serves as a guide for positioning the circuit board 30.

[0040] As shown in Figure 8, two partition walls 24 are formed parallel to each other in the middle of the longitudinal direction of the top plate 21. A recess 26 is formed between the two partition walls 24 and a part of the top plate 21. In the battery holder 20, the portion of these two partition walls 24 and the portion of the top plate 21 substantially constitute the spacer portion 25. The recess 26 is formed in a slit shape and both sides are closed. In the example shown in Figure 8, one side of the recess 26 is closed by a part of the side wall 22 (in the middle in the figure). (Filling hole 14)

[0041] Furthermore, as shown in Figures 9-10, 14-15, etc., the outer casing 10 has filling holes 14 and air holes 15. These filling holes 14 and air holes 15 are spaced apart from each other. The filling holes 14 are holes for filling the space between the inner surface of the outer casing 10 and the surfaces of the multiple battery blocks 2 in the internal space. Here, as shown in Figure 10, a tubular or straw-shaped injection tube TB is inserted into the interior of the outer casing 10 through the filling holes 14, and the uncured filler material 50 is filled between the inner surface of the second main surface 12a of the case and the surface of the second main surface 2b of the block. (Filler material 50)

[0042] The filler material 50 can be a liquid material in its uncured state with excellent thermal conductivity, preferably a potting material such as silicone resin or urethane resin. By filling the inside of the outer case 10 with the filler material 50 and eliminating the voids, the air layer that would act as an insulating layer is eliminated, improving thermal conductivity and thus improving the heat dissipation of the battery pack 100. Furthermore, if an air layer exists inside the outer case 10, there is a risk of the air layer burning because the oxygen contained in the air layer is flammable. By eliminating the air layer, the flammability of the material is removed, thus improving explosion-proof properties. (Air holes 15)

[0043] The air holes 15 are for releasing air from the internal space when filling the internal space with the filler material 50 from the filling holes 14.

[0044] The filling hole 14 is opened on the inner surface of the outer case 10 at a position that communicates with the space between the block end faces 2c. In examples such as Figures 2 and 6, two battery blocks 2, each composed of a rectangular secondary battery cell 1, are housed side by side along the longitudinal direction of the outer case 10. Therefore, the space between the block end faces 2c is located midway in the first direction, which is the longitudinal direction. When filling the filling material 50 from the filling hole 14, if the filling material 50 does not travel a long distance in the first direction through the internal space of the outer case 10 to reach the end face, the filling material 50 will stop midway, causing a so-called short circuit of the filling material 50 and creating a gap. Therefore, by opening the filling hole 14 approximately in the center of the first direction of the outer case 10, the filling material 50 can be advanced almost evenly through the internal space from the filling hole 14 to each end face in the longitudinal direction, thereby reducing the risk of a short circuit.

[0045] Further, the filling hole 14 preferably opens in the middle in the second direction intersecting the first direction, that is, the short side direction of the outer case 10. Accordingly, the filler 50 can be advanced substantially evenly toward the side surface from the filling hole 14 opened substantially at the center in the width direction, and the risk of the filler 50 shorting can be reduced as well.

[0046] The spacer portion 25 communicates with the filling hole 14 and forms a guiding path for guiding the filler 50 into the internal space. With such a configuration, when the filler 50 is filled into the internal space from the filling hole 14, it is possible to smoothly guide it through the guiding path of the spacer portion 25. (Guide rib 60)

[0047] Further, as shown in FIG. 11, the outer case 10 is provided with a guide rib 60 on the inner surface of the second main surface 12a of the case. The guide rib 60 is a member for inhibiting the uncured filler 50 filled between the inner surface of the second main surface 12a of the case and the surface of the second main surface 2b of the block from being filled in the second direction intersecting the first direction through the filling hole 14. By providing the guide rib 60 in this way, an effect of controlling the flow path and speed of the filler 50 can be obtained. Specifically, as shown in FIG. 12, when trying to fill the uncured filler 50 inside the outer case 10, it becomes easier to be filled in the short side direction indicated by arrow A than in the longitudinal direction indicated by arrow B in the figure. As a result, the short side direction of A is filled first, and the filling in the longitudinal direction of B becomes slow, and the filler 50 from the A side blocks the air hole 15 before the filling from the B side, and the bubbles from the B side cannot escape. Therefore, by providing the guide rib 60 and inhibiting the uncured filler 50 from advancing in the second direction which is the short side direction as indicated by the thin arrow in FIG. 11, it becomes easier to be filled in the first direction as indicated by the thick arrow. As a result, it is possible to adjust the filling speeds on the A side and the B side and perform a well-balanced filling operation. As a result, uniform filling of the filler 50 in the internal space can be achieved, and an effect of suppressing the generation of bubbles and enhancing heat dissipation and explosion protection can be obtained.

[0048] The guiding rib 60 is preferably formed in a pair of wall shapes extending in the first direction so as to sandwich the region corresponding to the filling hole 14 on the inner surface of the second main surface 12a of the case. As a result, even with the wall-shaped guiding rib 60 extending in the first direction, the progress of the uncured filling material 50 in the second direction intersecting the first direction is blocked, making it relatively easier to progress in the first direction and facilitating the filling of the uncured filling material 50 in the longitudinal direction.

[0049] Also, the guiding rib 60 is preferably formed such that the width of the pair of walls widens as it moves away from the region corresponding to the filling hole 14 in the first direction. Thus, while preventing the uncured filling material 50, which has just been supplied from the filling hole 14 into the internal space and has momentum, from spreading in the second direction by sandwiching it from both sides with the narrow-width guiding rib 60, the filling material 50 can be easily diffused by making it wider in the first direction and weakening the resistance.

[0050] Furthermore, the guiding rib 60 preferably has a pair of walls extending radially from the region corresponding to the filling hole 14 toward the rectangular corners of the second main surface 12a of the case. Thereby, while guiding the filling material 50 in the first direction, the guiding rib 60 with a further spreading shape guides the uncured filling material 50 guided in the first direction toward the corners where the filling of the filling material 50 is likely to be short and an air layer is likely to occur, making it easier to fill the filling material 50 in the four corners of the second main surface 12a of the case and suppressing the formation of air layers and bubbles. In the example of FIG. 11, the guiding rib 60 is generally formed in an X shape or a hyperbolic shape.

[0051] Such a guiding rib 60 can be formed integrally with the second main surface 12a of the case. Thereby, the guiding rib 60 can be formed on the second main surface 12a of the case at low cost and easily. (Block wall portion 70)

[0052] Furthermore, as shown in the exploded perspective view of Figure 5, the battery block 2 has a block wall portion 70 formed on its side surface along the first direction. The block wall portion 70 has a notch formed in the area facing the corner of the outer case 10. With this configuration, when the uncured filler material 50 filled between the second main surface 12a of the outer case 10 and the second main surface 2b of the block gradually rises in water level and reaches the first main surface 11a of the case and the first main surface 2a of the block, it flows in all at once from the side of the battery block 2 toward the center, thereby suppressing the situation in which the filler material 50 advancing from both sides mix in the center and is prone to generating air bubbles. In other words, by blocking the filler material 50, which tends to move in the shorter direction where its travel distance is relatively short, with the block wall portion 70, and guiding the filler material 50 to the first main surface 11a of the case through a notch formed near the corner of the outer case 10, the travel distance of the filler material 50 is increased, allowing the filler material 50 to gradually mix together and suppressing the generation of air bubbles. (Communication opening 27)

[0053] The spacer portion 25 of the battery holder 20 has a U-shaped recess 26 in cross-section, which forms part of the guide path. The spacer portion 25 also has a communication opening 27 at the bottom of the recess 26 that connects to the filling hole 14. The lower part of the communication opening 27 is formed in a U-shape in cross-section so that it opens downwards. The communication opening 27 is also opened at the bottom of the recess 26. In plan view, the communication opening 27 is positioned to overlap with the filling hole 14. This allows the spacer portion 25 to be provided between the battery blocks 2, while the communication opening 27 is positioned to overlap with the filling hole 14, so that the spacer portion 25 does not obstruct the filling of the filler material 50.

[0054] Furthermore, the partition wall 24 is formed in a curved shape 27b in cross-section so as to extend from the inner surface of the communication opening 27 across the recess 26. This allows the filler material 50 introduced from the filling hole 14 through the communication opening 27 into the recess 26 to be smoothly guided to the bottom surface of the internal space of the outer case 10, as shown in Figure 10. (First case 11)

[0055] The first case 11 is shown in Figures 13 to 17. As shown in these figures, the distance between the inner surface of the first main surface 11a of the case and the surface of the first main surface 2a of the block is maximized in the region D1 where the filling holes 14 are provided, and decreases as you move away from the filling holes 14 towards the first main surface 11a of the case. Here, the inner surface of the first main surface 11a of the case is formed in a mortar shape, being thinner towards the region D1 where the filling holes 14 are provided and thicker towards the surrounding area D2. With this configuration, when filling the internal space with uncured filler 50, residual air is more easily collected in the region where the filling holes 14 are provided, and the situation in which air bubbles remain in the cured filler 50 can be suppressed. Furthermore, the distance between the inner surface of the first main surface 11a of the case and the surface of the first main surface 2a of the block is minimized at the four corners of the first case 11 of the outer case 10 on the inner surface of the first main surface 11a of the case. Therefore, it is possible to prevent air bubbles from remaining in the four corners of the first case 11.

[0056] Because many fillers such as potting agents have high viscosity, it is not easy to spread the filler evenly into the gap between the inner surface of the outer case and the surface of the battery block. In particular, since the inner surface of the upper case is generally flat, the filler sometimes diffuses irregularly, resulting in residual air bubbles. In contrast, as shown in Figures 13, 15 to 17, etc., the battery pack 100 according to this embodiment has the inner surface of the first main surface 11a of the case formed in a mortar shape, and an air hole 15 is provided in the region at the apex, making it possible to direct the flow of the filler 50 regularly in the intended direction.

[0057] Multiple air holes 15 can be opened on either side of the filling hole 14. By opening multiple air holes 15 in this way, air can be released from areas where air bubbles tend to accumulate to the outside of the outer case 10, effectively suppressing the generation of air bubbles.

[0058] In the examples shown in Figures 13, 15-16, etc., the inner surface of the first main surface 11a of the case is formed in an isosceles trapezoid shape with the region where the filling holes 14 are provided as the upper edge when viewed in cross-section along the first direction. The air holes 15 are opened on the slanted sides of the isosceles trapezoid shape. With this configuration, by making the inner surface of the first main surface an isosceles trapezoid shape in cross-section along the first direction, when filling the internal space with uncured filler material 50, residual air is guided along the slanted sides, making it easier for air to escape through the air holes 15 opened on the slanted sides, thereby suppressing the situation in which air bubbles remain in the cured filler material 50.

[0059] In this disclosure, the term "isosceles trapezoid" does not necessarily mean strictly isosceles trapezoids; for example, the corners may be chamfered. It may also be formed by curves with curved edges or vertices. Curves that are roughly close to isosceles trapezoids are also included in the definition of isosceles trapezoid in this disclosure. In the example shown in Figure 13, the inner surface of the first main surface 11a of the case is a truncated pyramid, but it may also be a truncated cone or a dome shape.

[0060] Furthermore, as shown in Figures 15 and 17, the inner surface of the first main surface 11a of the case is formed in an isosceles trapezoidal shape with the region where the filling holes 14 are provided as the upper edge, even when viewed in cross-section along the second direction. As a result, the inner surface of the first main surface 11a of the case is mortar-shaped in all directions of the vertical and horizontal x and y planes, which guides residual air along the inclined surface when filling the internal space with uncured filler 50, making it easier for it to escape through the air holes 15 and suppressing the situation in which air bubbles remain in the cured filler 50. (Opening rib 16)

[0061] Furthermore, as shown in Figure 18, the air hole 15 is provided with an opening rib 16 that protrudes along the opening edge on the inner surface of the first main surface 11a of the case. With this configuration, the opening rib 16 prevents the filler material 50 from being discharged from the air hole 15, thereby gaining time before the filler material 50 is discharged from the air hole 15. During this time, air bubbles are guided into the air hole 15 and made easier to discharge, thus preventing air bubbles from remaining.

[0062] The spacer portion 25 of the battery holder 20 can have a groove portion 28 formed on its surface, spaced apart from the air hole 15. In the example shown in Figure 4, the groove portion 28 extends to the left and right of the filling hole 14. By forming the groove portion 28 on the top surface of the battery holder 20 in this way, it is possible to suppress the situation in which the filler material 50 tries to go to the air hole 15 by the shortest distance. In other words, the filler material 50 supplied to the internal space tries to flow along the path with the least resistance. Generally, a path with little resistance is a path with a short path length. As a result, as shown by the solid arrows in the cross-sectional view of Figure 17, the filler material 50 supplied from the filling hole 14 flows laterally through the slit-shaped recess 26, or passes through the core block 4 and travels along the bottom surface and side surface of the core block 4, with a portion of it wrapping around to the top surface of the core block 4. This filler material 50 tries to go to the air hole 15 by the shortest distance, as shown by the dashed line. This makes it difficult to fill every corner of the internal space with the filler material 50. In contrast, in the battery pack 100 according to this embodiment, a groove 28 is formed in the top plate 21 of the battery holder 20, thereby guiding the filler material 50 that has wrapped around to the upper surface of the core block 4 towards the groove 28, thereby hindering the movement of the filler material 50 that would otherwise try to reach the air hole 15 by the shortest distance. By restricting the movement of the filler material 50 in this way, it becomes possible to direct the filler material 50 in a direction that allows it to spread uniformly within the internal space.

[0063] In the example shown in Figure 4, the groove 28 is formed to be continuous with the side surface of the filling hole 14. However, this disclosure is not limited to a configuration in which the groove 28 is in a straight line passing through the filling hole 14; for example, it may be formed on the opposite side of the filling hole from the side closer to the air hole. Furthermore, the groove may be formed in multiple lines. In this way, the groove may be formed in other patterns that restrict the movement of the filler material attempting to shortcut through the air hole. (Spacer recess 29)

[0064] Furthermore, as shown in Figure 8, the spacer portion 25 of the battery holder 20 has a spacer recess 29 formed in a part of the recess 26 for positioning the bridge piece 43 of the intermediate lead plate 40. This allows the bridge piece 43 of the intermediate lead plate 40 to be positioned in the guide path of the spacer portion 25 without interfering with anything. (Circuit board 30)

[0065] The battery pack 100 also includes a circuit board 30 electrically connected to a plurality of secondary battery cells 1. The battery block connector 3 is connected to the circuit board 30 via an intermediate lead plate 40, a first lead plate 46, and a second lead plate 47. In the examples shown in Figures 4 and 6, the first lead plate 46 is connected to the negative electrode side of the battery block connector 3, and the second lead plate 47 is connected to the positive electrode side of the battery block connector 3. In Figure 6, the first lead plate 46 and the second lead plate 47 are welded to the battery block 2 (secondary battery cell 1), respectively. At this stage, the tips of the first lead plate 46 and the second lead plate 47 are not bent but are in an extended position. In this state, the battery block connector 3 is covered with a battery holder 20. At this time, the third connecting piece 44 is bent to the top surface 21 of the battery holder 20. Also, as shown in Figure 6, the circuit board 30 is fixed to the side wall 22 of the battery holder 20. At this time, the tips of the first lead plate 46 and the second lead plate 47 are folded back onto the circuit board 30. The intermediate lead plate 40 connects the intermediate potential of the battery block connector 3 to the circuit board 30. The circuit board 30 implements a charge / discharge circuit for charging and discharging the secondary battery cell 1, and a protection circuit that monitors the voltage and temperature of the secondary battery cell 1 and cuts off the current in case of abnormality. The circuit board 30 is made of a glass epoxy substrate or the like. A substrate holder for holding such a circuit board 30 may also be provided.

[0066] As shown in Figures 5 and 6, the circuit board 30 is positioned on one side of the battery holder 20 so as to overlap with the side wall 22. In this configuration, where the circuit board 30 is positioned on the side of the core block 4, the circuit board 30 may obstruct the flow path of the filler material 50, potentially preventing it from filling the entire internal space of the outer casing 10. Therefore, a notch 32 is provided in the circuit board 30 to ensure a flow path for the filler material 50.

[0067] In the examples shown in Figures 4 and 5, the circuit board 30 has a substrate notch 32 formed in the portion that intersects with the guide path. By partially forming the substrate notch 32 on the circuit board 30, which must be positioned in a orientation that intersects with the guide path, it is possible to suppress the situation in which the filling of the filler material 50 is obstructed by the circuit board 30. (Spacer notch 22b)

[0068] Furthermore, the spacer portion 25 of the battery holder 20 has a spacer notch 22b formed in a part of the side wall 22, with a recess 26 partially exposed. The notch of the battery holder 20 is aligned with the substrate notch 32 of the circuit board 30, as shown in Figure 5, etc. In this way, when filling the filler material 50 from the filling hole 14, the spacer notch 22b and the substrate notch 32 are positioned to intersect the flow of the filler material 50 pushed towards the circuit board 30 along the slit-shaped recess 26, allowing the filler material 50 to pass through the spacer notch 22b and the substrate notch 32, thus enabling the filler material 50 to proceed along its guide path without obstructing its flow. It is preferable that the spacer notch 22b be the same size as or smaller than the substrate notch 32. This makes it possible to control the flow of the filler material 50 during filling by the size of the spacer notch 22b. [Battery pack manufacturing method]

[0069] Next, an example of a manufacturing method for the battery pack 100 will be described. Here, the battery pack 100 comprises one or more battery blocks 2, each having an opposing first main surface 2a and a second main surface 2b of the block; an outer case 10 that houses the battery blocks 2 in its internal space; and a filler material 50 that is filled between the inner surface of the outer case 10 and the surface of the battery blocks 2 in the internal space. First, the battery blocks 2 are housed in the internal space of the outer case 10. The outer case 10 has an outer shape in plan view that is rectangular and extended in the first direction. The inner surface of the outer case 10 has a first main surface 11a of the case that is opposite to the first main surface 2a of the block; and a second main surface 12a of the case that is opposite to the second main surface 2b of the block.

[0070] Next, the injection tube TB is inserted through the filling hole 14 opened in the first main surface 11a of the case. Then, the filler material 50 is filled in the internal space between the inner surface of the second main surface 12a of the case and the surface of the second main surface 2b of the block through the injection tube TB in an uncured state. At this time, air bubbles contained in the uncured filler material 50 are removed through air holes 15 that are opened at a distance from the filling hole 14 on the inner surface of the first main surface 11a of the case, which is formed in a mortar shape with the filling hole 14 at its apex.

[0071] As described above, the uncured filler material 50 is filled into the bottom, side, and top surfaces of the internal space of the outer case 10, thereby filling the entire internal space of the outer case 10 with the filler material 50. Finally, the uncured filler material 50 filled into the internal space is cured. This makes it easier for residual air to collect in the area where the filling holes 14 are provided when filling the internal space with the uncured filler material 50, thereby suppressing the situation in which air bubbles remain in the cured filler material 50.

[0072] The above examples illustrate the use of a battery pack as a power source for portable electrical devices. However, this disclosure is not limited to this, and the battery pack can also be used for other purposes, such as supplying power to various types of electrical devices that are driven by mobile devices. Examples of electrical devices include portable electrical devices and mobile devices such as electric vehicles and electric carts. In such electrical devices, if the remaining capacity of the battery pack becomes low or if the battery pack deteriorates over time, the battery pack can be replaced, allowing the electrical device to continue to be used. However, this disclosure is not limited to replaceable battery packs that mainly house secondary battery cells, but can also be applied to configurations in which secondary battery cells are housed within the casing of the electrical device. In this disclosure, a battery pack is defined as one in which secondary battery cells are housed within a case, and also includes those in which the secondary battery cells for driving are built into the casing of the electrical device itself. In other words, this disclosure is not limited to replaceable battery packs, but can also be applied to electrical devices that have built-in secondary battery cells.

[0073] The battery pack and its manufacturing method according to the present invention can be suitably used as a power source for wireless devices, a power source for portable electrical equipment such as electric cleaners and power tools, a power source for mobile devices such as electric scooters, electric carts and electric assist bicycles, a backup power source for servers, and a stationary energy storage device for home, office, and factory use.

[0074] 100...Battery pack 1...Secondary battery cell 2...Battery block; 2a...First main surface of block; 2b...Second main surface of block; 2c...End surface of block 3...Battery block connector 4...Core block 10...Outer case 11...First case; 11a...First main surface of case 12...Second case; 12a...Second main surface of case 14...Filling hole 15...Air hole 16...Opening rib 20, 20B...Battery holder 21...Top plate 22...Side wall; 22b...Spacer cutout 23...End wall 24...Partition wall 25...Spacer section 26...Recess 27...Communication opening; 27b...Curved surface 28...Groove section 29...Spacer recess 30...Circuit board 32...Board cutout 40...Intermediate lead plate 43...Bridge piece 46...First lead plate 47...Second lead plate 50...Filler material 60...Guiding rib 70...Block wall section TB...Injection pipe D1...Maximum distance between the inner surface of the first main surface of the case and the outer surface of the first main surface of the block D2...Minimum distance between the inner surface of the first main surface of the case and the outer surface of the first main surface of the block

Claims

1. A battery pack comprising: one or more battery blocks, each having a first main surface and a second main surface of a block facing each other; an outer case for housing the battery blocks in an internal space; and a filler material filled between the inner surface of the outer case and the surface of the battery blocks in the internal space, wherein the outer case has an outer shape in plan view that is formed in a rectangular shape extended in a first direction, and its inner surface has a first main surface of the case facing the first main surface of the block and a second main surface of the case facing the second main surface of the block, and a filling hole for filling the filler material in an uncured state between the inner surface of the outer case and the surface of the battery blocks in the internal space, and an air hole opened at a distance from the filling hole, opening on the first main surface of the case, and the inner surface of the first main surface of the case is formed in a mortar shape such that the distance between the inner surface of the first main surface of the case and the surface of the first main surface of the block is greatest in the region where the filling hole is provided, and approaches as the distance moves away from the filling hole in the direction of the first main surface of the case.

2. A battery pack according to claim 1, wherein the distance between the inner surface of the first main surface of the case and the surface of the first main surface of the block is minimized at the four corners of the outer case on the inner surface of the first main surface of the case.

3. A battery pack according to claim 1, wherein a plurality of air holes are opened so as to sandwich the filling hole.

4. A battery pack according to claim 1, wherein the inner surface of the first main surface of the case is formed in an isosceles trapezoidal shape with the region where the filling holes are provided as the upper edge when viewed in cross-section along the first direction, and the air holes are opened on the slanted edges of the isosceles trapezoidal shape.

5. A battery pack according to claim 4, wherein the inner surface of the first main surface of the case is formed in an isosceles trapezoidal shape with the region where the filling holes are provided as the upper edge, in a cross-sectional view along a second direction intersecting the first direction.

6. A battery pack according to claim 1, wherein the filling hole is opened midway between the first direction and the second direction intersecting the first direction.

7. A battery pack according to any one of claims 1 to 6, wherein the air hole is provided with an opening rib that protrudes along the opening edge on the inner surface of the first main surface of the case.

8. A battery pack according to any one of claims 1 to 6, wherein the inner surface of the second main surface of the case is provided with guide ribs to prevent the uncured filler material, which is filled between the inner surface of the second main surface of the case and the surface of the second main surface of the block through the filling hole, from being filled in a second direction intersecting the first direction.

9. A battery pack according to claim 8, wherein the guide ribs are formed in the inner surface of the second main surface of the case as a pair of wall-like structures extending in the first direction, sandwiching a region corresponding to the filling hole.

10. A battery pack according to claim 9, wherein the guide ribs are formed such that the width of the pair of wall-like structures widens as they move away from the region corresponding to the filling hole in the first direction.

11. A battery pack according to claim 10, wherein the guide ribs extend radially from the region corresponding to the filling hole toward the rectangular corner of the second main surface of the case, the pair of wall-like structures.

12. A battery pack according to claim 11, wherein the guide rib is formed integrally with the second main surface of the case.

13. A battery pack according to any one of claims 1 to 6, wherein the outer case is divided into a first case and a second case, and the first case has a first main surface and the second case has a second main surface.

14. A battery pack according to any one of claims 1 to 6, wherein the filler is a silicone resin or a urethane resin.

15. A battery pack according to any one of claims 1 to 6, wherein one or more battery blocks have block walls formed on their sides along the first direction, and the block walls have notches formed in the region facing the corners of the outer casing.

16. A battery pack according to any one of claims 1 to 6, wherein one or more battery blocks communicate with the filling hole and form a communication opening for guiding the uncured filler material between the inner surface of the second main surface of the case and the surface of the second main surface of the block through the filling hole.

17. A battery pack according to claim 16, wherein the one or more battery blocks comprise two battery blocks, and the communication port is formed between the two battery blocks.

18. A method for manufacturing a battery pack comprising: one or more battery blocks, each having a first main surface and a second main surface of a block facing each other; an outer case for housing the battery blocks in an internal space; and a filler material filled between the inner surface of the outer case and the surface of the battery blocks in the internal space, the method comprising: a step of housing the battery blocks in the internal space of the outer case, the outer case having an outer shape in plan view that is formed in a rectangular shape extended in a first direction, and whose inner surface has a first main surface of the case facing the first main surface of the block and a second main surface of the case facing the second main surface of the block; a step of inserting an injection tube through a filling hole opened in the first main surface of the case, filling the internal space with the filler material in an uncured state from the injection tube, and removing air bubbles contained in the uncured filler material guided between the inner surface of the first main surface of the case and the surface of the first main surface of the block through an air hole opened at a distance from the filling hole on the inner surface of the first main surface of the case, which is formed in a mortar shape with the filling hole as its apex; A method for manufacturing a battery pack, comprising the step of curing the uncured filler material that has been filled into the internal space.

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