BATTERY PACK

Abstract

A battery pack includes a plurality of battery cells and holder that has battery cells arranged in a parallel posture. Holder has partition wall between adjacent battery cells for arranging battery cells at fixed positions. Partition wall has a surface facing battery cells as resin molded layer shaped to arrange battery cells at the fixed positions. Partition wall has a three-layer structure that non-melting plate is disposed inside and resin molded layer is laminated on both surfaces of non-melting plate. Holder is formed in a single-piece structure by molding resin molded layer from a synthetic resin.

Claims

1. A battery pack comprising: a plurality of battery cells; and a holder holding the plurality of battery cells to be arranged in a parallel posture, wherein the holder includes a partition wall between adjacent two of the plurality of battery cells to arrange the plurality of battery cells at fixed positions, the partition wall has a three-layer structure including: resin molded layers each having a surface facing a corresponding battery cell of the each adjacent two of the plurality of battery cells, and the surface being shaped to arrange the corresponding battery cell at the fixed positions, and to non-melting plate is disposed inside and being sandwiched by the resin molded layers, and the holder further includes a synthetic resin molding the resin molded layers to be integrated into a single piece.

2. The battery pack according to claim 1, wherein the plurality of battery cells are cylindrical batteries, the holder comprising plastic, the plastic having an insertion gap for disposing the non-melting plate at a fixed position inside the resin molded layer, the plastic having the surface facing the corresponding battery cell, the surface being curved along a surface of the corresponding battery cell, and the non-melting plate is disposed in the insertion gap.

3. The battery pack according to claim 1, wherein the non-melting plate is an inorganic plate.

4. The battery pack according to claim 3, wherein the non-melting plate is a mica plate.

5. The battery pack according to claim 1, wherein the holder includes: a holding tube for storing each of the plurality of battery cells inside, and an inflow space provided outside the holding tube, the inflow space being a space into which the holding tube flows when the holding tube is melted by heat.

6. The battery pack according to claim 5, wherein the holder holding tubes each being the holding tube, the holding tubes being arranged in multiple stages and multiple rows, the partition wall is cross-shaped and provided between the holding tubes arranged vertically and horizontally, and includes an inflow space being elongated along a length of the plurality of battery cells, and being located in a central portion of the partition wall being cross-shaped.

7. The battery pack according to claim 5, wherein the holder includes an insertion gap having the inflow space in the partition wall located between adjacent holding tubes of the holding tubes, the insertion gap includes: a holding gap for disposing the non-melting plate at a fixed position, the holding gap sandwiching a central portion of the non-melting plate, and the inflow space, and a lateral width of the holding gap is narrower than a lateral width of the non-melting plate, and the inflow space is provided on both side portions of the non-melting plate.

8. The battery pack according to claim 2, wherein the non-melting plate is disposed so as to be freely placed into and taken out of the insertion gap.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a perspective view of a battery pack according to an exemplary embodiment of the present invention.

[0022] FIG. 2 is a cross-sectional view of the battery pack shown in FIG. 1 taken along line II-II.

[0023] FIG. 3 is an exploded perspective view of the battery pack shown in FIG. 1.

[0024] FIG. 4 is a perspective view of a battery block.

[0025] FIG. 5 is an exploded perspective view of the battery block shown in FIG. 4.

[0026] FIG. 6 is a perspective view of a core pack in which two battery blocks and a circuit board are coupled.

DESCRIPTION OF EMBODIMENT

[0027] Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, terms to denote specific directions or positions (e.g., “top”, “bottom”, and other terms including those terms) are used as necessary for easy understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meanings of the terms. The parts having the same reference numerals appearing in a plurality of drawings indicate the same or equivalent parts or members.

[0028] The exemplary embodiment described below is specific examples of the technical idea of the present invention, and the present invention is not limited to the following exemplary embodiment. The dimensions, materials, shapes, relative arrangements, and the like of the components described below are not intended to limit the scope of the present invention thereto but are intended for exemplification, unless specifically stated. The contents described in relation to one exemplary embodiment and example can be applied to other exemplary embodiments and examples. The sizes and positional relationships of members shown in the drawings may be exaggerated in order to clarify the explanation.

[0029] FIGS. 1 to 5 show a battery pack according to one exemplary embodiment of the present invention. FIG. 1 is a perspective view of the battery pack, FIG. 2 is a vertical cross-sectional view of the battery pack, and FIG. 3 is an exploded perspective view of the battery pack. FIG. 4 is a perspective view of a battery block built in the battery pack, FIG. 5 is an exploded perspective view of the battery block, and FIG. 6 is a perspective view of a battery core pack in which two battery blocks and a circuit board are coupled. Battery pack 100 shown in FIGS. 1 to 6 includes a plurality of battery cells 1 and holder 2 in which battery cells 1 are arranged in a parallel posture. Battery pack 100 shown in FIGS. 2 and 3 includes exterior case 9 that houses two sets of battery blocks 10 arranged in the longitudinal direction, and circuit board 4.

[0030] Battery pack 100 is used as a power source for a mobile device such as a vacuum cleaner. However, the present invention does not limit the use of the battery pack to a mobile device. The battery pack is also applicable to other mobile devices such as an electric tool and an assisted bicycle, for example. The battery pack shown in the drawings is structured to be detachably coupled to a portable device. However, the battery pack of the present invention can also be used by being incorporated in a portable device in a non-detachable state.

[0031] (Exterior Case 9)

[0032] Battery pack 100 is formed in a rectangular tubular box shape as shown in FIGS. 2 and 3. Exterior case 9 shown in the drawings is divided into two parts, case body 9A and closing part 9B. Exterior case 9 has connector 19 drawn to the outside for connecting with a portable device that is to be supplied power from battery pack 100. Exterior case 9 is made of a material having excellent electrical insulating properties and thermal insulating properties, for example, resin such as polycarbonate.

[0033] Inside exterior case 9 stores, as shown in FIG. 3, two sets of battery blocks 10, insulating plate part 11 disposed between battery blocks 10, and circuit board 4 connected to battery blocks 10. As shown in FIGS. 4 and 5, battery block 10 has a plurality of battery cells 1 arranged in parallel posture in holder 2. In illustrated battery block 10, four battery cells 1 are arranged in two rows and two stages in holder 2. Battery cell 1 uses a cylindrical battery having a cylindrical exterior can. In illustrated battery block 10, four battery cells 1 are arranged in two rows and two stages, and battery cells 1 are connected in series by lead plates 3. In illustrated battery block 10, four battery cells 1 are arranged in two rows and two stages and connected in series. However, a number and connection form of battery cells can be freely changed.

[0034] Battery cell 1 is a lithium ion secondary battery. However, battery cell 1 can be a non-aqueous electrolyte secondary battery other than a lithium-ion secondary battery. The cylindrical battery cell may be a rechargeable secondary battery such as a nickel metal hydride battery or a nickel cadmium battery, especially a battery that generates heat at high temperatures when being used.

[0035] Battery cells 1 are electrically connected in series by lead plates 3. Lead plate 3 is formed by bending a metal plate having excellent conductivity. Lead plate 3 is welded to an electrode on an end surface of battery cell 1. Lead plate 3 with battery cell 1 is connected to circuit board 4. Circuit board 4 has a charge/discharge circuit and a protection circuit mounted thereon. Circuit board 4 is connected to output lead part 3x for inputting positive or negative output of each battery block 10, or is connected to intermediate potential lead part 3y for measuring intermediate potential in order to detect a voltage of each battery cell 1. In addition, circuit board 4 may be connected to potential of a temperature detector (not illustrated) for detecting a temperature of each battery cell 1. The temperature detector can be a thermistor or the like.

[0036] (Insulation Plate Part 11)

[0037] As shown in FIG. 3, inside exterior case 9 has insulating plate part 11 disposed between battery blocks 10. Insulating plate part 11 is disposed between battery blocks 10 arranged side by side in the longitudinal direction of exterior case 9. Insulating plate part 11 is an inorganic plate made from a material having excellent insulating properties and heat insulating properties, for example, such as a mica plate.

[0038] (Battery Block 10)

[0039] Battery block 10 has four battery cells 1 arranged at fixed positions in plastic holder 2. Battery block 10 shown in FIGS. 4 and 5 has holder 2 divided into first holder 2A and second holder 2B in the longitudinal direction of battery cells 1. First holder 2A and second holder 2B are separately manufactured by molding plastic, and battery cells 1 are inserted and coupled to each other. First holder 2A and second holder 2B each have cylindrical holding part 21 for inserting cylindrical battery cells 1 and arranging the same at fixed positions. An inner shape of holding part 21 is substantially the same as an outer shape of battery cell 1, and to be exact, the inner shape of holding part 21 is slightly larger to smoothly insert and arrange battery cells 1 at fixed positions. First holder 2A and second holder 2B of this structure are coupled to each other at fixed positions with battery cells 1 therebetween in a state where both ends of cylindrical battery cells 1 are inserted. First holder 2A and second holder 2B can be more accurately coupled to each other with opposing surfaces as a fitting structure, and are also coupled together at fixed positions with a non-melting plate described later.

[0040] (Holder 2)

[0041] In order to arrange four battery cells 1 in a parallel posture, holder 2 shown in FIGS. 3 and 4 is molded into a shape in which four sets of holding tubes 22 are coupled in two rows and two stages in a parallel posture, and holding part 21 is formed such that an inside of each holding tube 22 is made substantially equal to the outer shape of battery cell 1. Holding tube 22 defines partition wall 23 between adjacent battery cells 1. In illustrated holder 2, since battery cells 1 are arranged in two rows and two stages, cross-shaped partition wall 23 is provided between the four sets of battery cells 1 arranged vertically and horizontally. Partition wall 23 has a three-layer structure of non-melting plate 13 and resin molded layers 12 in which resin molded layer 12 is provided on the surface facing battery cell 1 and non-melting plate 13 is disposed inside resin molded layer 12. Partition wall 23 has a three-layer structure in which resin molded layers 12 are laminated on both sides of internal non-melting plate 13. Resin molded layer 12 has a surface molded into a curved surface along a surface of cylindrical battery cell 1 to arrange battery cell 1 at a fixed position.

[0042] Holder 2 of FIGS. 4 and 5 has inflow spaces 24 and 27 for heat-melted holding tube 22 outside holding tube 22. In holder 2 of FIGS. 4 and 5, holding tubes 22 are arranged in multiple stages and multiple rows, in two rows and two stages in these drawings, cross-shaped partition wall 23 is provided between holding tubes 22 arranged vertically and horizontally, and inflow space 24 is provided in the center of cross-shaped partition wall 23. Inflow space 24 is provided in a hollow part of cross-shaped partition wall 23, as a rectangular hollow part extending in the longitudinal direction of battery cell 1. Inflow space 24 provided in this part has a large internal volume so that the heat-melted resin of holding tube 22 can smoothly flow into this space.

[0043] Holder 2 of FIG. 4 further has inflow spaces 27 provided on both sides of insertion gap 25 for disposing non-melting plate 13 at a fixed position. Inflow spaces 27 each are provided such that flat-surface parts facing each other are placed at portions of an outer surfaces of adjacent cylindrical holding tubes 22, holding gap 26 for non-melting plate 13 is provided between the facing flat-surface parts, and a lateral width of holding gap 26 is made narrower than a lateral width of non-melting plate 13, in other words, an entire width of insertion gap 25. Insertion gap 25 has inflow spaces 27 on both sides of holding gap 26 of non-melting plate 13. Holding gap 26 sandwiches non-melting plate 13 between both sides and holds at a fixed position. Inflow spaces 27 are on both sides of insertion gap 25 and allow the heat-melted resin of holding tube 22 to flow in.

[0044] Holder 2 described above has inflow spaces 24 and 27 into which the heat-melted synthetic resin of holding tube 22 is to flow at the both sides of insertion gap 25 and the hollow parts of cross-shaped partition wall 23. In this holder 2, when battery cell 1 generates abnormal heat and holding tube 22 is heat-melted, the heat-melted synthetic resin flows into inflow spaces 27 on the both sides of insertion gap 25. Melted synthetic resin flowing into these spaces melts the synthetic resin between inflow spaces 27 and inflow space 24 provided in the hollow part of the cross-shaped partition wall 23, and then flows into inflow space 24 provided in the hollow part of cross-shaped partition wall 23 as shown by arrows A. The heat-melted synthetic resin flows into inflow space 24 and is cooled. When the synthetic resin is heat-melted and flows into inflow space 24, an air layer is formed between battery cell 1 and non-melting plate 13, and a heat insulation effect of this air layer prevents induction of thermal runaway to adjacent battery cells 1. Since holder 2 of FIG. 2 also has inflow space 27 outside lower holding tubes 22, when any of battery cells 1 inside lower holding tubes 22 generates abnormal heat and holding tube 22 is heat-melted, the melted synthetic resin flows into inflow spaces 27 provided below holding tube 22 and is cooled. In addition, the air layer is provided between battery cell 1 and non-melting plate 13 to insulate the heat and prevent thermal runaway.

[0045] (Non-Melting Plate 13)

[0046] Non-melting plate 13 is a plate that does not deform at the temperature of battery cell 1 having generated abnormal heat, and preferably an inorganic plate such as a mica plate. As the inorganic plate, instead of the mica plate, one obtained by sintering or molding inorganic powder into a plate shape, or a plate-shaped inorganic material, or a plate-shaped inorganic fiber material can be used. As the non-melting plate, a plate material slightly thinner than the insertion gap is used such that it can be detachably disposed in the insertion gap.

[0047] Battery pack 100 described above is assembled in the following steps.

[0048] (1) Battery cells 1 and non-melting plates 13 are arranged and coupled at fixed positions in first holder 2A and second holder 2B. First holder 2A and second holder 2B are coupled in a state where battery cells 1 are inserted into corresponding holding parts 21 and non-melting plates 13 are inserted into corresponding insertion gaps 25 of partition wall 23. First holder 2A and second holder 2B are coupled by a locking structure, and are also coupled at fixed positions via built-in battery cells 1 and non-melting plates 13.

[0049] (2) Lead plates 3 are connected to end surface electrodes of battery cells 1 exposed from both end surfaces of holder 2 so that all battery cells 1 housed in holder 2 are connected in series. Lead plates 3 are electrically connected and fixed by welding to the end surface electrodes of battery cells 1.

[0050] Battery block 10 is manufactured through the above steps.

[0051] (3) Two battery blocks 10 are coupled with insulating plate part 11 sandwiched therebetween. Two battery blocks 10 are arranged side by side in the axial direction of battery cells 1, and are insulated by insulating plate part 11 interposed therebetween.

[0052] (4) Circuit board 4 is coupled to two battery blocks 10. Holder 2 shown in FIGS. 3 to 6 includes projecting part 29 on an upper surface, and projecting part 29 is guided to concave part 4a provided on an outer peripheral edge of circuit board 4 to dispose circuit board 4 at a fixed position. Further, holder 2 shown in the diagrams includes locking hook 30 protruding from the upper surface, and this locking hook 30 is locked to circuit board 4 and is coupled at a fixed position by a locking structure. Circuit board 4 is fixed to holder 2 by screwing set screws 18 penetrating circuit board 4 into fixing bosses 28 provided on the upper surface of holder 2.

[0053] (5) Output lead parts 3x and intermediate potential lead parts 3y drawn from lead plates 3 are electrically coupled to circuit board 4 connected to battery block 10. Output lead parts 3x and intermediate potential lead parts 3y are disposed so as to project from an upper surface of battery block 10, are inserted into connection holes 4b provided in circuit board 4 and disposed at fixed positions, and are electrically connected and physically coupled to circuit board 4 by soldering.

[0054] In the above state, as shown in FIG. 6, battery core pack 20 in which circuit board 4 is coupled to two battery blocks 10 is manufactured.

[0055] (6) Battery core pack 20 is stored in exterior case 9. Circuit board 4 shown in the diagram is connected to output connector 19. Battery core pack 20 is stored in case body 9A of exterior case 9 such that connector 19 passes through open window 9a in case body 9A, and then case body 9A is closed with closure part 9B. Then, open window 9a of case body 9A is closed by closure lid 17.

INDUSTRIAL APPLICABILITY

[0056] The battery pack of the present invention is suitably used as a power source for portable devices such as vacuum cleaners, electric power tools, and assisted bicycles.

REFERENCE MARKS IN THE DRAWINGS

[0057] 100 battery pack [0058] 1 battery cell [0059] 2 holder [0060] 2A first holder [0061] 2B second holder [0062] 3 lead plate [0063] 3x output lead part [0064] 3y intermediate potential lead part [0065] 4 circuit board [0066] 4a concave part [0067] 4b connection hole [0068] 9 exterior case [0069] 9A case body [0070] 9a open window [0071] 9B closing part [0072] 10 battery block [0073] 11 insulation plate part [0074] 12 resin molded layer [0075] 13 non-melting plate [0076] 17 closure lid [0077] 18 set screw [0078] 19 connector [0079] 20 core pack [0080] 21 holding part [0081] 22 holding tube [0082] 23 partition wall [0083] 24 inflow space [0084] 25 insertion gap [0085] 26 holding gap [0086] 27 inflow space [0087] 28 fixing boss [0088] 29 projecting part [0089] 30 locking hook