Battery pack

Abstract

This battery pack comprises a battery block of a plurality of battery cells, a circuit substrate, a substrate holder, and potting resin with which the substrate holder is filled to embed the circuit substrate. In the substrate holder, the circuit substrate is disposed in a storage part of a bottom plate having a peripheral wall, a filling gap for the potting resin is provided between the circuit substrate and the bottom plate, and pouring grooves of the potting resin are provided in the bottom plate. The potting resin is adhered to the circuit substrate by potting resin on a front surface and potting resin on a rear surface. The potting resin on the rear surface connects rib-shaped potting resin, formed by the potting resin being injected into and cured in the pouring grooves, into an integrated structure.

Description

Battery pack

[0001] The present invention relates to a battery pack in which a circuit board is embedded in a potting resin.

[0002] A battery pack has been developed in which a circuit board fixed to a board holder is embedded in potting resin (see Patent Document 1). This battery pack achieves various advantages by embedding the circuit board in potting resin. For example, the potting resin can improve the waterproofing of the circuit board and the heat dissipation characteristics of heat-generating components mounted on the circuit board. This battery pack can be manufactured by injecting uncured paste-like or liquid potting resin into the housing of the board holder in which the circuit board is placed, adhering the potting resin to both sides of the circuit board, and embedding the circuit board in the potting resin. The potting resin used to embed the circuit board can be poured tightly into both sides of the circuit board, especially into narrow filling gaps on the backside of the circuit board, to closely embed the potting resin on both sides of the circuit board. The potting resin that flows into the filling gap and hardens has the advantage of connecting the circuit board and board holder into an integrated structure and protecting the circuit board.

[0003] Japanese Patent Application Laid-Open No. 2005-209995

[0004] The battery pack described above has a filling gap between the circuit board and the bottom plate into which uncured potting resin is poured. The filling gap can be widened to allow the uncured potting resin to flow without leaving any gaps. However, a wide filling gap poses the problem of increasing the amount of potting resin required, resulting in higher material costs and a thicker board holder for mounting the circuit board. While this problem can be solved by narrowing the filling gap as much as possible, a narrow filling gap reduces the fluidity of the uncured potting resin, making it difficult to inject it into the interior, resulting in the creation of voids.

[0005] The present invention was developed with the aim of solving the above problems, and one of the objects of the present disclosure is to provide a battery pack in which uncured potting resin can be smoothly poured into the filling gap between the circuit board and the board holder, thereby embedding the circuit board in the potting resin.

[0006] A battery pack according to one embodiment of the present disclosure has all of the following configurations (a) to (e): (a) The battery pack includes a battery block having a plurality of battery cells, a circuit board connected to the battery block, a board holder that secures the circuit board, and a filling section that is formed by potting resin that is filled into the board holder to embed the circuit board. (b) The board holder includes a bottom plate with a peripheral wall, and the inside of the bottom plate serves as a storage section. The circuit board is placed in the storage section, and a filling gap for the filling section is provided between the circuit board and the bottom plate. (c) The board holder includes a potting resin pouring groove in the bottom plate. (d) The filling section that embeds the circuit board includes a front filling section that is in close contact with the front surface of the circuit board and a back filling section that is in close contact with the back surface of the circuit board. (e) The back filling section integrally connects a rib-shaped filling section that is poured into the pouring groove and hardened.

[0007] The above battery pack has the advantage that uncured potting resin can be smoothly poured into the gap between the circuit board and the board holder, and the circuit board can be embedded in a desirable state in the filled portion formed by the potting resin.

[0008] 1 is a schematic perspective view showing a battery pack according to one embodiment of the present invention. FIG. 1 is a schematic perspective view of a battery block, a board holder, and a circuit board. FIG. 2 is a schematic exploded perspective view of the board holder and the circuit board. FIG. 3 is a schematic plan view and an enlarged view of a main part showing a state in which a circuit board is arranged in the board holder. FIG. 4 is a schematic cross-sectional view taken along line VIII-VIII of the enlarged view of a main part of FIG. 4 in a state in which the circuit board is embedded in potting resin. FIG. 5 is a schematic cross-sectional view taken along line IX-IX of the enlarged view of a main part of FIG. 4 in a state in which the circuit board is embedded in potting resin.

[0009] The present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms including these terms) will be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same or equivalent parts or members.

[0010] Furthermore, the embodiments shown below are specific examples of the technical concept of the present invention and are not intended to limit the present invention thereto. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended as examples and are not intended to limit the scope of the present invention thereto. Furthermore, the content described in one embodiment or example can also be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity of explanation.

[0011] The embodiments of the present disclosure may be specified by the following configurations and features.

[0012] A battery pack according to one embodiment of the present disclosure has all of the following configurations (a) to (e): (a) The battery pack includes a battery block having a plurality of battery cells, a circuit board connected to the battery block, a board holder for securing the circuit board, and a filling section formed of potting resin that is filled into the board holder to embed the circuit board. (b) The board holder includes a bottom plate with a peripheral wall, the inside of which serves as a storage section, and the circuit board is placed in the storage section, with a filling gap in the filling section between the circuit board and the bottom plate. (c) The board holder includes a potting resin pouring groove in the bottom plate. (d) The filling section in which the circuit board is embedded includes a front filling section that is in close contact with the front surface of the circuit board and a back filling section that is in close contact with the back surface of the circuit board. (e) The back filling section integrally connects a rib-shaped filling section that is poured into the pouring groove and hardened.

[0013] The above battery pack has the advantage that the potting resin smoothly flows into the gap between the circuit board and the board holder, making it difficult for gaps to remain unfilled. The potting resin that flows between the circuit board and the bottom plate adheres to the entire back surface of the circuit board, providing ideal insulation for the circuit board. Furthermore, the filling section formed by the potting resin on the back surface integrally connects the circuit board and the bottom plate of the board holder, ensuring reliable fixation of the circuit board to the board holder. The battery pack's smooth filling of the gap with uncured potting resin is achieved by providing a pouring groove in the bottom plate, which improves the fluidity of the uncured potting resin. The improved fluidity of the uncured potting resin allows it to smoothly flow into the gap and then diffuse to both sides, filling the entire gap.

[0014] Furthermore, in the battery pack described above, the potting resin on the back surface integrally connects the circuit board and the bottom plate of the board holder, and the uncured potting resin that flows into the pouring groove hardens to form a rib-shaped filling portion that is integrally connected to the filling portion on the back surface to form a reinforcing rib, thereby reinforcing the filling portion on the back surface. Furthermore, the ribs on the bottom plate of the board holder improve the strength of the board holder itself, and the filling portion on the back surface reinforced by the rib-shaped filling portion is integrally connected to the circuit board, contributing to the alleviation of external stress on the circuit board.

[0015] Another embodiment of the battery pack disclosed herein includes an inlet opening for uncured potting resin between the side edge of the circuit board and the inner surface of the peripheral wall. The potting resin injected into the inlet opening can be cured to form a filling portion of the connecting part that connects the front filling portion and the back filling portion. The filling portion of the connecting part connects the front filling portion and the back filling portion into an integral structure. In this battery pack, uncured potting resin can be smoothly poured from the inlet opening into the filling gap of the bottom plate to embed the circuit board in the filling portion. In addition, uncured potting resin can be filled from the inlet opening into the pouring groove and diffused throughout the filling gap via the pouring groove, filling the entire filling gap. Furthermore, the filling portion formed by the potting resin filled into the inlet opening connects the front filling portion and the back filling portion into an integral structure via the filling portion of the connecting part, allowing the circuit board to be embedded in the filling portion.

[0016] In another embodiment of the battery pack of the present disclosure, an inlet opening can be opened in communication with the end of the pouring groove. The battery pack described above has an inlet opening that is in communication with the end of the pouring groove, which allows uncured potting resin to be smoothly poured into the pouring groove through the inlet opening. The pouring groove into which the uncured potting resin has been poured smoothly injects the potting resin into the filling gap. Furthermore, this structure provides a stronger, integrated connection between the backside filling portion that fills and hardens in the inlet opening and the rib-shaped filling portion that fills and hardens in the pouring groove, thereby providing stronger reinforcement for the embedded circuit board.

[0017] In another embodiment of the battery pack of the present disclosure, the peripheral wall of the board holder has a protruding peripheral wall that protrudes in the width direction, and an inlet opening can be provided between the protruding peripheral wall and the outer periphery of the circuit board. The battery pack described above has an inlet opening between the protruding peripheral wall provided on the peripheral wall of the board holder and the outer periphery of the circuit board, which increases the opening area of ​​the inlet opening, allowing uncured potting resin to be smoothly poured into the filling gap and the pouring groove. Furthermore, the above structure also achieves the advantage of increasing the cross-sectional area of ​​the filling portion of the connecting part that hardens at the inlet opening with a larger opening area, thereby connecting the front filling portion and the back filling portion into an integral structure with a stronger filling portion of the connecting part, allowing the circuit board to be embedded in the filling portion in a more preferable state.

[0018] In another embodiment of the battery pack of the present disclosure, the inlet opening can be a slit-like opening extending along the longitudinal direction of the side edge of the circuit board. This battery pack has the advantage that the inlet opening is elongated and slit-like, and an inlet opening with a large opening area is provided on the side edge of the circuit board, allowing uncured potting resin to smoothly flow into the filling gap and the pouring groove.

[0019] In another embodiment of the battery pack of the present disclosure, the board holder includes a pair of opposing peripheral walls extending longitudinally along both sides of the circuit board, each of which may include multiple protruding peripheral walls. In this battery pack, the opposing peripheral walls include multiple protruding peripheral walls, and inlet openings are provided between the respective side edges of the circuit board and the protruding peripheral walls, allowing uncured potting resin to be more smoothly poured into the filling gap and the pouring groove from the respective inlet openings. This allows the potting resin to be reliably poured into the entire filling gap, even in the case of a long, narrow circuit board.

[0020] In another embodiment of the battery pack of the present disclosure, a notch can be provided on the outer periphery of the circuit board. In the battery pack described above, the notch on the outer periphery of the circuit board can serve as an inlet opening for injecting uncured potting resin into the back surface of the circuit board. Therefore, a large inlet opening can be provided without providing a protruding peripheral wall on the peripheral wall of the board holder, or by reducing the protrusion of the protruding peripheral wall. Therefore, the battery pack described above has the advantage that the opening area of ​​the inlet opening can be increased without increasing the width of the board holder, allowing uncured potting resin to be poured into the filling gap and the pouring groove. Furthermore, the above structure can also have the notch positioned opposite the protruding peripheral wall to further increase the size of the inlet opening.

[0021] In another embodiment of the battery pack of the present disclosure, the bottom plate may be provided with multiple rows of pouring grooves. This battery pack has the advantage that even for a long and narrow circuit board, multiple rows of pouring grooves are provided at intervals along the length of the circuit board, allowing the uncured potting resin to be smoothly filled throughout the entire filling gap.

[0022] In another embodiment of the battery pack of the present disclosure, the circuit board is a double-sided board with components mounted on both sides, and the rear-side components mounted on the rear side of the circuit board can be embedded in a rib-shaped filling portion formed by hardening a potting resin in a pouring groove. This battery pack has the advantage that the rear-side components mounted on the rear side of the circuit board can be placed inside the pouring groove, improving space efficiency and allowing the double-sided board to be placed close to the bottom plate. Another advantage is that a portion of the rear-side components can be embedded in the filling portion injected into the pouring groove, thereby more reliably connecting the filling portion and the circuit board, particularly with improved peel strength.

[0023] In another embodiment of the battery pack disclosed herein, the battery block includes a plurality of battery cells and a battery holder in which the battery cells are arranged in fixed positions, the battery cells being cylindrical batteries, the battery holder having grooves between adjacent cylindrical batteries, and the pouring grooves in the bottom plate being arranged in the valley grooves of the battery holder. The above battery pack improves space efficiency by arranging the pouring grooves in the bottom plate in the valley grooves of the battery holder, allowing the board holder to be arranged close to the battery holder. This allows the board holder to have pouring grooves in the bottom plate, allowing uncured potting resin to be smoothly injected into the filling gap, while still achieving a compact overall battery pack.

[0024] (Embodiment 1) A battery pack 1 includes a battery block 3 consisting of a plurality of battery cells 2, a circuit board 4 connected to the battery block 3, a board holder 5 to which the circuit board 4 is fixed, and a filling section 6 to which the circuit board 4 is fixed to the board holder 5. The filling section 6 is made of potting resin.

[0025] (Battery Block 3) The battery pack 1 in Figures 1 to 9 includes a battery block 3 consisting of multiple battery cells 2, a circuit board 4 connected to the battery block 3, and a board holder 5 to which the circuit board 4 is fixed. The circuit board 4 is embedded in a filling section 6 and arranged in a fixed position in the board holder 5. This disclosure does not specify the type, shape, arrangement, alignment, or connection of the battery cells 2. For example, the battery block 3 shown in the cross-sectional view of Figure 5 has multiple rechargeable battery cells 2 arranged in a parallel position in a battery holder 7. The battery cells 2 in this figure are cylindrical batteries 2A, and multiple cylindrical batteries 2A are arranged vertically in multiple rows and columns, like a straw bale stack. The battery cells 2 are rechargeable secondary batteries, and lithium-ion secondary batteries can be used. However, this disclosure does not specify that the battery cells 2 be lithium-ion batteries; all other rechargeable secondary batteries can be used, including currently used batteries such as lithium polymer secondary batteries and all-solid-state batteries to be developed in the future. Furthermore, although the battery pack 1 in FIG. 5 has cylindrical battery cells 2A, the battery cells 2 may be batteries other than cylindrical batteries, for example, prismatic batteries.

[0026] The battery block 3 has multiple battery cells 2 arranged in a parallel position in battery holders 7 and connected in parallel or in series with lead plates (not shown). The battery block 3 can be divided into parallel units by connecting multiple battery cells 2 in parallel. This battery block 3 can increase the output voltage by connecting multiple parallel units in series.

[0027] The battery holder 7 holds multiple battery cells 2 in fixed positions. The battery holder 7 is made by molding a material with excellent insulating properties, preferably thermoplastic plastic. The battery holder 7 holds each battery cell 2 in a parallel position, with the end faces of the battery cells 2 positioned on the same plane.

[0028] The battery holder 7 has multiple cell retention openings 7A into which battery cells 2 are inserted and held in place. Each cell retention opening 7A has an interior shape that follows almost the entire periphery of the surface of the battery cell 2. The battery holder 7 positions each battery cell 2 in a predetermined position by inserting a battery cell 2 into each cell retention opening 7A.

[0029] The battery block 3 shown in the cross-sectional view of Figure 5 has cylindrical battery 2A battery cells 2 arranged in a bale-like configuration. As shown in Figure 5, a battery block 3 with cylindrical batteries 2A arranged in a bale-like configuration can have valley grooves 7B on the top surfaces of the battery holders 7. This battery holder 7 can have multiple valley grooves 7B on its top surface, giving it a wave-like shape that conforms to the top surfaces of the cylindrical batteries 2A. As shown in the enlarged cross-sectional view of Figure 6 and the enlarged perspective cross-sectional view of Figure 7, the valley grooves 7B can be effectively used as space to guide the ridges 11A that protrude from the underside of the pouring grooves 8 provided in the bottom plate 11 of the board holder 5, which will be described later.

[0030] (Circuit Board 4) The circuit board 4 is connected to the battery block 3 via lead wires (not shown) and is mounted with electronic components that implement a protection circuit (not shown) that controls the charging and discharging of the battery cells 2. The circuit board 4 is a double-sided board with components such as semiconductor elements that control charging and discharging mounted on both the front and back sides, allowing components to be placed in optimal positions. The semiconductor elements control the charging and discharging of the battery block 3. The protection circuit detects the voltage, remaining capacity, temperature, current, etc. of the battery cells 2 that make up the battery block 3 and controls the charging and discharging current to prevent overcharging and over-discharging of the battery cells 2. The protection circuit can also detect abnormal conditions in the battery cells 2 and control the charging and discharging current to prevent deterioration of the battery cells 2 and degradation of their electrical characteristics. The semiconductor elements of the protection circuit are FETs, transistors, etc.

[0031] The semiconductor elements that control the charge and discharge current of the battery block 3 generate heat due to Joule heat. Joule heat increases in proportion to the product of the square of the flowing current and the equivalent resistance. Because the semiconductor elements control the charge and discharge current of the battery block 3, the amount of heat generated increases as the load current or charging current of the battery pack 1 increases. For example, if the load current or charging current doubles, the heat energy of the semiconductor elements increases fourfold, causing a rise in temperature. The semiconductor elements require heat dissipation to maintain their temperature below a preset level.

[0032] The circuit board 4 embedded in the filling portion 6 can dissipate the thermal energy of heat-generating components such as semiconductor elements through the filling portion 6. The filling portion 6 is in close contact with the surface of the heat-generating components such as semiconductor elements in a favorable thermal bond state, thereby efficiently dissipating the thermal energy. The filling portion 6 that embeds the double-sided board is in close contact with the heat-generating components such as semiconductor elements mounted on both sides of the circuit board 4, thereby efficiently dissipating heat.

[0033] (Board Holder 5) The board holder 5 shown in the exploded perspective view of FIG. 3 and the plan view of FIG. 4 positions and secures the circuit board 4 in a fixed position. While the filling section 6 is not shown in these figures, the circuit board 4 is embedded in the filling section 6 and positioned in a fixed position, as described below. The filling section 6 is composed of a potting resin that is fluid in its uncured state and is injected into the board holder 5 to fill it, then hardens to embed the circuit board 4. A transparent urethane resin, for example, is suitable for the filling section 6. Urethane resin is a resin that hardens through a chemical reaction between a polyol and an isocyanate curing agent. However, this disclosure does not limit the filling section 6 to urethane resin. Any resin that is fluid in its uncured state and can harden to embed the circuit board 4 in the board holder 5, such as epoxy resin or silicone resin, can be used. In the battery pack 1, the board holder 5 is positioned and secured by being close to and connected to the battery block 3. This disclosure does not specify the placement or position of the board holder 5, but the board holder 5 can be positioned and secured to the side of the battery block 3, as shown in FIG. 2, for example.

[0034] The board holder 5 shown in the exploded perspective view of FIG. 3 has a bottom plate 11 and a peripheral wall 9 connected to the outer edge of the bottom plate 11. The board holder 5 of FIG. 3 has the peripheral wall 9 disposed around the bottom plate 11, and the inside of the peripheral wall 9 forms a storage section 10 for storing a circuit board 4. The board holder 5 has a gap above the bottom plate 11 for arranging the circuit board 4. The board holder 5 of FIG. 6 (FIG. 5) has the circuit board 4 disposed parallel to the bottom plate 11, and a filling gap 12 for filling the filling section 6 between the circuit board 4 and the bottom plate 11. The storage section 10 is an area surrounded by the bottom plate 11 and the peripheral wall 9 that surrounds the periphery, and the circuit board 4 is disposed inside and embedded in the filling section 6. The board holder 5 fills the storage section 10, which secures the circuit board 4, with uncured potting resin to form the filling section 6, and embeds the circuit board 4 in the cured filling section 6. With the circuit board 4 secured in the storage section 10 of the board holder 5, uncured potting resin is injected into the storage section 10 to embed the circuit board 4 in the filling section 6. The filling section 6 hardens to secure the circuit board 4 to the board holder 5. Furthermore, the filling section 6 is in close contact with both sides of the circuit board 4 and with the mounted components, such as semiconductor devices, mounted on the circuit board 4, thereby embedding the circuit board 4. The filling section 6, which is in close contact with the circuit board 4 and the mounted components, not only secures the circuit board 4 to the board holder 5 without misalignment, but also thermally bonds with the heat-generating mounted components in an optimal state, absorbing and dissipating the thermal energy of the mounted components. The cross-sectional perspective view of FIG. 7 shows the circuit board 4 placed in the storage section 10 of the board holder 5 embedded in the filling section 6.

[0035] (Bottom Plate 11) In the board holder 5 shown in the exploded perspective view of FIG. 3 and the plan view of FIG. 4, the bottom plate 11 is provided with a pouring groove 8 that improves the fluidity of the uncured potting resin and smoothly injects it into the filling gap 12. The pouring groove 8 enlarges the cross-sectional area of ​​the flow path on the back side of the circuit board 4, improving the fluidity of the supplied uncured potting resin and forming a flow path for quickly pouring the uncured potting resin throughout the filling gap 12. The filling gap 12 can be widened vertically to smoothly fill the uncured potting resin to its interior. However, widening the vertical width (H) of the filling gap 12 has the drawback of separating the circuit board 4 from the bottom plate 11, making the board holder 5 substantially thicker and bulkier, and increasing the overall size of the battery pack 1. Another drawback is the increased amount of potting resin required, which increases material costs. Narrowing the filling gap 12 allows the board holder 5, on which the circuit board 4 is mounted, to be substantially thinner, and also reduces the amount of potting resin used, thereby reducing material costs. However, narrow filling gap 12 makes it difficult for the uncured potting resin to flow smoothly into the interior, resulting in the problem of a void 6 on the back surface of circuit board 4 where the potting resin is not filled. By forming pouring groove 8 in a groove shape that is partially recessed from the bottom surface of bottom plate 11, on the one hand, the vertical width (H) of filling gap 12 is within an appropriate range, narrowing filling gap 12 and substantially thinning board holder 5 for mounting circuit board 4, thereby reducing the amount of potting resin. On the other hand, the cross-sectional area of ​​the flow path on the back side of circuit board 4 is partially expanded, improving the fluidity of the uncured potting resin and allowing it to flow smoothly into filling gap 12. As shown in the cross-sectional view of Figure 7, the vertical width (H) of filling gap 12 is set narrow in the portion where pouring groove 8 is not provided. 8, in the portion where the pouring groove 8 is provided, the cross-sectional area of ​​the flow path on the back side of the circuit board 4 is partially expanded by the depth (d) of the pouring groove 8 in addition to the vertical width (H) of the filling gap 12. Furthermore, the pouring groove 8 can be reinforced as a bead, thereby improving the strength of the board holder 5.

[0036] In the board holder 5 having the pouring groove 8 in the bottom plate 11, the vertical width (H) of the filling gap 12 can be set to an optimum value taking into consideration the fluidity of the uncured potting resin and the width of the circuit board 4. For example, in a battery pack 1 using a urethane resin as the potting resin, the filling gap 12 can be set to 2 mm or more, and the pouring groove 8 in the bottom plate 11 can be used to fill the entire filling gap 12 with uncured potting resin to form the filling portion 6.

[0037] The pouring grooves 8 are grooves for improving the fluidity of the uncured potting resin flowing into the filling gap 12, allowing the uncured potting resin to flow smoothly into the filling gap 12 between the circuit board 4 and the bottom plate 11. The pouring grooves 8 increase the cross-sectional area of ​​the flow path, thereby improving the fluidity of the uncured potting resin. As shown in the exploded perspective view of FIG. 3 , in a slender circuit board 4, multiple rows of pouring grooves 8 extending in the width direction, i.e., the lateral direction of the circuit board 4, are provided in parallel on the bottom plate 11, allowing the uncured potting resin to fill the entire filling gap 12 and form the filling section 6. The board holder 5 having multiple rows of pouring grooves 8 on the bottom plate 11 has the advantage that the multiple pouring grooves 8 increase the cross-sectional area of ​​each flow path in multiple regions of the filling gap 12, improving the fluidity. This allows the uncured potting resin to be uniformly filled over the entire surface of the slender circuit board 4 and form the filling section 6 without creating unfilled voids.

[0038] The cross-sectional shape and position of the multiple rows of pouring grooves 8 are set to optimal values ​​taking into consideration the fluidity of the uncured potting resin that makes up the filling portion 6. As shown in the enlarged cross-sectional view of Figure 6, the depth (d) and inner width (w) of the cross-sectional area of ​​the pouring grooves 8 can be set to 10% or more, preferably 20% or more, of the vertical width (H) of the filling gap 12, for example, in a transparent urethane resin, and the inner width (w) of the pouring grooves 8 can be set to, for example, 1 to 10 times, preferably 1 to 5 times, the depth (d) of the pouring grooves 8, thereby improving the fluidity of the uncured potting resin poured into the filling gap 12.

[0039] The board holder 5 shown in Figure 4 has an inlet opening 13 between the peripheral wall 9 and the outer periphery of the circuit board 4, through which uncured potting resin is poured onto the back surface of the circuit board 4. The inlet opening 13 is an opening through which uncured potting resin supplied onto the circuit board 4 is poured onto the back surface of the circuit board 4. The board holder 5 has an inlet opening 13 that communicates with the end of the pouring groove 8. The pouring groove in Figure 4 has a pouring groove 8 with an inlet opening 13 at one end and a pouring groove with inlet openings 13 at both ends. This structure has the advantage that the uncured potting resin flowing in from the inlet opening 13 can be smoothly poured into the pouring groove and smoothly injected into the entire filling gap.

[0040] The board holder 5 shown in Figures 3 and 4 has a protruding peripheral wall 9B that protrudes outward from a portion of the peripheral wall 9. An inflow opening 13 for the uncured potting resin that constitutes the filling portion 6 is provided inside the protruding peripheral wall 9B. The inflow opening 13, shown in the enlarged view of Figure 4, is slit-shaped and extends in the width direction of the pouring groove 8. This board holder 5 can increase the width of the protruding peripheral wall 9B, i.e., the slit, thereby increasing the opening area of ​​the inflow opening 13. The inflow opening 13 can also be increased in width by widening the slit. The inflow opening 13 with a large opening area has the advantage of allowing the uncured potting resin to more smoothly flow onto the back surface of the circuit board 4 and be injected into the pouring groove 8. The inflow opening 13 is an opening through which the uncured potting resin is poured from top to bottom of the circuit board 4. The filling portion 6, formed by the potting resin filled in the inflow opening 13, hardens to become the filling portion 6C, which connects the filling portion 6A on the front surface with the filling portion 6B on the back surface. The filling portion 6C of the connecting portion serves as a protective cover for the outer periphery of the circuit board 4 and also protects the embedded circuit board 4 by integrally connecting the front filling portion 6A and the back filling portion 6B. The protruding peripheral wall 9B (FIG. 8) of the peripheral wall of the board holder 5 (FIG. 7) protrudes widthwise, increasing the opening area of ​​the inlet opening 13, making it easier to pour uncured potting resin onto the back surface of the circuit board 4 and further allowing it to be poured into the pouring groove 8. Once hardened, the filling portion 6C of the connecting portion connects the front filling portion 6A and the back filling portion 6B into an integral structure, allowing the circuit board 4 to be embedded in the filling portion 6 in a desirable state and protecting it. The back filling portion 6B is integrally connected to the rib-shaped filling portion 6D, further reinforcing and protecting the circuit board 4.

[0041] The board holder 5 is molded from insulating plastic into a shape in which the bottom plate 11 and peripheral wall 9 are integrally formed. The board holder 5 shown in the plan view of FIG. 4 has a pair of opposing peripheral walls 9A extending longitudinally on both sides of the circuit board 4, with multiple protruding peripheral walls 9B on each opposing peripheral wall 9A, and inlet openings 13 at opposing positions on both sides of the circuit board 4. The inlet openings 13 provided between the protruding peripheral walls 9B and the side edges of the circuit board 4 communicate with the ends of the pouring groove 8 at both ends. The board holder 5, which has multiple inlet openings 13 at opposing positions on both sides of the circuit board 4, allows uncured potting resin to flow from each inlet opening 13 into the pouring groove 8, ensuring reliable and stable injection of potting resin into the entire filling gap 12 between the bottom plate 11 and the circuit board 4, even for a long and narrow circuit board 4.

[0042] As shown by the dashed line in the enlarged cross-sectional view of FIG. 4 , the circuit board 4 can have a notch 4A on its outer periphery. The notch 4A is preferably positioned opposite the protruding peripheral wall 9B. This notch 4A enlarges the gap between the notch 4A and the inner surface of the protruding peripheral wall 9B provided on the peripheral wall 9, thereby increasing the opening area of ​​the inlet opening 13. Alternatively, the notch 4A can be positioned at the inlet opening 13 of the board holder 5, eliminating the need for a protruding peripheral wall 9B on the peripheral wall 9 or reducing the protrusion of the protruding peripheral wall 9B to provide an inlet opening 13 with a larger opening area. A circuit board 4 with a notch 4A has the advantage of allowing uncured potting resin to flow more smoothly from the inlet opening 13 into the filling gap 12.

[0043] 3 and 4 have multiple pouring grooves 8 formed in the bottom plate 11 extending widthwise in the middle of the circuit board 4, improving the fluidity of the uncured potting resin so that it can be poured into the filling gap 12 without leaving any gaps. The uncured potting resin, whose fluidity has been improved by the pouring grooves 8, fills the entire filling gap 12. The bottom plate 11 of FIG. 3 has six rows of pouring grooves 8 extending widthwise. This board holder 5 fills the multiple pouring grooves 8 with uncured potting resin, increasing the filling amount and volume of the filling section 6 and enabling it to absorb more heat energy from the circuit board 4 and heat-generating components.

[0044] For example, the filling volume of the filling portion 6 in which the circuit board 4 is embedded is set to 44,500 mm ２ The substrate holder 5 is provided with six rows of pouring grooves 8 each having a depth of 2 mm, an inner width of about 4 mm, and a length (L) of 60 mm, so that the filling volume of the substrate holder 5 is 47,380 mm ２ The board holder 5 with an increased filling volume of the filling portion 6 can increase the heat capacity absorbed from the embedded circuit board 4, and can efficiently dissipate the heat energy of the heat-generating components mounted on the circuit board 4.

[0045] The board holder 5 in Figure 4 also has inlet openings 13 at the corners of the outer periphery of the circuit board 4. These inlet openings 13 not only have the effect of quickly pouring uncured potting resin into the pouring grooves 8, but also have the advantage that the filling portions 6C of the connecting portions that harden inside the inlet openings 13 protect the corners of the circuit board 4, reinforce the corners of the peripheral wall 9 of the board holder 5 from the inside, relieve external stress, and prevent damage due to impacts such as being dropped. Furthermore, the filling portions 6C of the connecting portions that are injected into the inlet openings 13 on both sides of the circuit board 4 and harden also protect the circuit board 4 and board holder 5, relieve external stress on the circuit board 4 and board holder 5, and prevent damage due to impacts such as being dropped.

[0046] The filling section 6 in which the circuit board 4 is embedded sandwiches and reinforces the circuit board 4 between the front filling section 6A and the back filling section 6B, and the back filling section 6B is further reinforced by a rib-shaped filling section 6D that is poured into the pouring groove 8 and hardened, which has the effect of reinforcing the board holder 5 and the circuit board 4 and also has the effect of alleviating external stress applied to the circuit board 4 and protecting the circuit board 4. Furthermore, the filling section 6 in which the circuit board 4 is embedded has pouring grooves 8 formed in the bottom plate 11 and an integral rib-shaped filling section 6D, which increases the filling amount and volume of the filling section 6 and has the advantage of being able to increase the thermal energy absorbed from the thermal energy of the circuit board 4 and the mounted components.

[0047] As shown in the enlarged cross-sectional view of Figure 6, in the battery pack 1, a portion of the rear-surface components 14 mounted on the rear surface of the circuit board 4 can be placed inside the pouring groove 8 of the board holder 5 and embedded in the hardened rib-like filling portion 6D. This structure has the advantage that by placing the rear-surface components 14 protruding from the rear surface of the double-sided board, which has mounted components fixed to its rear surface, inside the pouring groove 8, the double-sided board can be placed close to the bottom plate 11 while ensuring the partial height of the mounted components with the filling gap 12 and pouring groove 8. Another advantage is that by embedding the rear-surface components 14 in the pouring groove 8, the filling portion 6 and the circuit board 4 can be connected more reliably, particularly with improved peel strength.

[0048] Furthermore, in the battery pack 1 shown in the cross-sectional view of Figure 6, the pouring grooves 8 on the bottom plate 11 of the board holder 5 are positioned in the valley grooves 7B on the surface of the battery block 3, and the board holder 5 is positioned close to the battery block 3. The battery block 3 shown in the figure uses cylindrical batteries 2A as battery cells 2, and these cylindrical batteries 2A are stacked in a bale-like manner in the battery holder 7, with valley grooves 7B provided between adjacent cylindrical batteries 2A. The battery holder 7 can be molded to a shape that fits the surface of the cylindrical batteries 2A, and valley grooves 7B can be provided on the surface. The bottom plate 11 of the board holder 5 can be provided with pouring grooves 8 and ridges 11A that protrude downward, and these ridges 11A are positioned in the valley grooves 7B of the battery holder 7. The battery pack 1 of this structure has the advantage that the entire battery pack 1 can be made compact by positioning the board holder 5 close to the battery block 3, injecting potting resin into the pouring groove 8, and reliably connecting the circuit board 4 and board holder 5 with the filling part 6.

[0049] The present disclosure can be effectively used as a battery pack in which uncured potting resin can be smoothly poured into the filling gap between the circuit board and the board holder, thereby embedding the circuit board in the potting resin.

[0050] DESCRIPTION OF SYMBOLS 1...Battery pack 2...Battery cell 2A...Cylindrical battery 3...Battery block 4...Circuit board 4A...Notch 5...Board holder 6...Filling section 6A...Filling section on front surface 6B...Filling section on back surface 6C...Filling section on connecting section 6D...Rib-shaped filling section 7...Battery holder 7A...Cell holding opening 7B...Valley groove 8...Pouring groove 9...Peripheral wall 9A...Opposite peripheral wall 9B...Protruding peripheral wall 10...Storage section 11...Bottom plate 11A...Convex rib 12...Filling gap 13...Inlet opening 14...Back surface part

Claims

1. A battery pack comprises: a battery block having a plurality of battery cells; a circuit board connected to the battery block; and a board holder fixing the circuit board; a filling section filled into the board holder to embed the circuit board, the filling section being made of potting resin; the board holder has a bottom plate with a peripheral wall, the inside of which is used as a storage section, the circuit board is placed in the storage section, and a filling gap for the filling section is provided between the circuit board and the bottom plate; the board holder has a pouring groove for the filling section in the bottom plate; the filling section embedding the circuit board comprises a front filling section that is in close contact with the front surface of the circuit board and a back filling section that is in close contact with the back surface of the circuit board; and the back filling section connects, in an integral structure, a rib-shaped filling section that is poured into the pouring groove and hardened.

2. A battery pack as claimed in claim 1, comprising an inlet opening for the unhardened potting resin between the side edge of the circuit board and the inner surface of the peripheral wall, the potting resin injected into the inlet opening hardening to form the filling section, and forming a filling section of a connecting section connecting the filling section on the front surface and the filling section on the back surface.

3. A battery pack according to claim 2, wherein the inlet opening is open and communicates with the end of the inlet groove.

4. A battery pack as claimed in claim 2, wherein the peripheral wall of the circuit board holder has a protruding peripheral wall that protrudes in the width direction, and the inlet opening is provided between the protruding peripheral wall and the outer periphery of the circuit board.

5. A battery pack according to claim 4, wherein the inlet opening is a slit extending along the longitudinal side edge of the circuit board.

6. A battery pack according to claim 4, wherein the board holder has a pair of opposing peripheral walls extending longitudinally along both sides of the circuit board, and each of the pair of opposing peripheral walls has the plurality of protruding peripheral walls.

7. A battery pack according to claim 4, wherein the circuit board has a notch on the outer periphery.

8. A battery pack according to any one of claims 1 to 7, wherein the bottom plate has a plurality of rows of the pouring grooves.

9. A battery pack as described in claim 1, wherein the circuit board is a double-sided board with components mounted on both sides, and the backside components mounted on the backside of the circuit board are embedded in the rib-shaped filling portion formed by hardening the potting resin in the pouring groove.

10. A battery pack as claimed in claim 1, wherein the battery block comprises the plurality of battery cells and a battery holder in which the plurality of battery cells are arranged in fixed positions, each of the plurality of battery cells being cylindrical batteries, the battery holder having valley grooves between adjacently arranged battery cells, and the pouring grooves of the bottom plate being arranged in the valley grooves of the battery holder.

Images