Battery pack

Abstract

The present invention achieves a high degree of safety by efficiently dissipating, to the outside, thermal energy from a battery that generates heat.　This battery pack is provided with a battery core block (10) obtained by arranging a plurality of battery cells at prescribed positions in a battery holder (2), and a casing accommodating the core block (10). The casing is provided with a heat dissipating case (4) of which both ends are open, and a closing portion for closing the opening portions at both ends of the heat dissipating case (4). The heat dissipating case (4) is provided with: a tube portion (6) inside which the core block (10) is disposed, and which is formed by shaping metal into a tubular shape; and a plurality of rows of heat absorbing fins (7) which are thermally coupled to an inside surface of the tube portion (6), project inward from the tube portion (6), and comprise a metal disposed in an attitude extending in an axial direction of the tube portion (6).

Description

[Technical Field]

[0001] The present invention relates to a battery pack in which a battery core block, which is made up of a plurality of battery cells arranged in fixed positions in a battery holder, is housed in a casing. [Background technology]

[0002] Battery packs for applications requiring high output, such as electric bicycles and assisted bicycles, have multiple battery cells connected in series and parallel and housed in a casing. This battery pack can increase the output voltage (V) by increasing the number of cells connected in series, and can also increase the battery capacity (Ah) by increasing the number connected in parallel.

[0003] As a battery pack for this purpose, a battery pack has been developed in which multiple cylindrical batteries are arranged in fixed positions using battery holders and housed in a casing (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-216366 Summary of the Invention [Problem to be solved by the invention]

[0005] FIG. 13 shows an exploded perspective view of the battery pack disclosed in Patent Document 1. In this battery pack, multiple battery cells are arranged in fixed positions in a battery holder 92 to form a core block 90, which is then inserted into a casing 93. The casing 93 houses the core block 90 inside, with both end faces of a cylindrical heat dissipation case 94 closed by closure sections 95 via packing 97. The heat dissipation case 94 is cylindrical with both ends open. As shown in the enlarged cross-sectional view of FIG. 14, to secure and close the closure sections 95 at the openings, the casing has multiple rows of fixing ribs 94a protruding from the inner surface and extending in the longitudinal direction. These fixing ribs 94a have threaded holes 94c extending in the longitudinal direction, into which set screws 96 are threaded to pass through the closure sections 95 and secure the closure sections 95 to both ends of the heat dissipation case 94.

[0006] When an internal short circuit occurs in a battery cell, reactions between the positive and negative electrode active materials and the electrolyte occur, and the electrolyte decomposes and vaporizes. These reactions generate heat, accelerating the reaction. As the reaction progresses, gas is generated, causing an abnormal increase in internal pressure. The battery cell's exhaust valve opens, expelling vaporized electrolyte and other high-temperature battery components in a short period of time. This accelerated reaction, which ultimately results in an explosion, is called "thermal runaway." The ejected material is a high-temperature, high-velocity powder mixture containing extremely hot, finely fragmented battery components and vaporized electrolyte components, accompanied by flames. It is ejected into the battery pack, triggering thermal runaway in other battery cells. This can lead to a chain reaction of thermal runaway, spreading from one battery cell to another, causing serious thermal damage and spreading to the entire battery pack. Furthermore, if the ejected material is not safely discharged from the battery pack after being sufficiently cooled, it can also cause serious thermal damage to connected devices.

[0007] In this respect, even if the above battery packs use a metal with excellent heat dissipation properties as the casing, they are unable to effectively cool the ejected material from a battery cell that has gone into thermal runaway. As a result, they are unable to effectively suppress thermal runaway in other battery cells, and are unable to discharge the ejected material outside the battery pack in a safe, sufficiently cooled state.

[0008] The present invention was developed with the aim of eliminating the above-mentioned drawbacks of the conventional technology, and one of its purposes is to provide a battery pack that effectively cools the heat generated inside the battery pack, in particular the ejection material from a battery cell that has gone into thermal runaway, thereby preventing serious thermal damage such as the spread of fire to the entire battery pack and thermal damage to connected devices, thereby achieving a high level of safety. [Means for solving the problem]

[0009] A battery pack according to one aspect of the present invention includes a battery core block in which multiple battery cells are arranged in fixed positions in a battery holder, and a casing that houses the core block. The casing includes a heat dissipation case with open ends and closing sections that close both end openings of the heat dissipation case. The heat dissipation case includes a cylindrical section formed from metal and having the core block arranged inside it, and multiple rows of metal heat absorption fins that are thermally coupled to the inner surface of the cylindrical section, protrude inward from the cylindrical section, and are arranged in a position that extends axially of the cylindrical section. [Effects of the Invention]

[0010] The battery pack described above efficiently dissipates heat generated inside the battery pack to the outside, achieving a high level of safety. In particular, the thermal energy of ejected material from a thermally runaway battery cell can be efficiently dissipated to the outside, suppressing thermal runaway in other battery cells, and the ejected material can be discharged outside the battery pack in a sufficiently cooled and safe state, preventing the entire battery pack from catching fire and thermal damage to connected devices, achieving a high level of safety. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic lateral end view of a battery pack according to a first embodiment of the present invention. [Figure 2] 1 is a schematic exploded perspective view of a battery pack according to a first embodiment of the present invention. [Figure 3]FIG. 10 is a schematic lateral end view of a battery pack according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic exploded perspective view of a battery pack according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a schematic lateral end view of a battery pack according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a schematic exploded perspective view of a battery pack according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a schematic lateral end view of a battery pack according to a fourth embodiment of the present invention. [Figure 8] FIG. 10 is a schematic exploded perspective view of a battery pack according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a schematic lateral end view of a battery pack according to a fifth embodiment of the present invention. [Figure 10] FIG. 10 is a schematic exploded perspective view of a battery pack according to a fifth embodiment of the present invention. [Figure 11] FIG. 10 is a schematic exploded perspective view of a battery pack according to a sixth embodiment of the present invention. [Figure 12] FIG. 10 is a schematic end view of a battery pack according to a seventh embodiment of the present invention. [Figure 13] FIG. 1 is an exploded perspective view of a conventional battery pack. [Figure 14] 14 is an enlarged cross-sectional view of a main part of a heat dissipation case of the battery pack shown in FIG. 13. DETAILED DESCRIPTION OF THE INVENTION

[0012] A battery pack according to one embodiment of the present invention comprises a battery core block in which multiple battery cells are arranged in fixed positions in a battery holder, and a casing that houses the core block, the casing having a heat dissipation case with open ends and closing sections that close the open ends of the heat dissipation case. The heat dissipation case has a cylindrical section in which the core block is arranged and made of metal and has multiple rows of heat absorption fins that are thermally bonded to the inner surface of the cylindrical section, protrude inward from the cylindrical section, and are arranged in a position that extends axially of the cylindrical section.

[0013] The battery pack described above efficiently dissipates the thermal energy of the ejected material from the battery cells to the outside, preventing thermal runaway in other battery cells, and discharges the ejected material to the outside in a sufficiently cooled and safe state, achieving a high level of safety. This is because the battery pack described above has a casing composed of a heat dissipation case with open ends and closing sections that close both end openings of the heat dissipation case, and the heat dissipation case further comprises a metal cylindrical section that houses the core block and multiple rows of metal heat absorption fins that are thermally coupled to the inner surface of the cylindrical section, protrude inward from the cylindrical section, and are arranged in an axial direction of the cylindrical section. The multiple rows of heat absorption fins that are thermally coupled to the inner surface of the cylindrical section and protrude inward efficiently absorb the thermal energy of the ejected material from the battery cells over a wide area, and the heat absorption fins that absorb the heat energy conduct the heat to the thermally coupled cylindrical section, and the cylindrical section to which the heat energy is conducted efficiently dissipates the heat to the outside over a wide area.

[0014] In a battery pack according to another embodiment of the present invention, the heat dissipation case has a cylindrical portion and heat absorption fins that are integrally formed from metal.

[0015] The battery pack described above has the advantage of achieving high safety by efficiently dissipating heat generated inside the battery pack to the outside. This is because the heat absorption fins and cylindrical portion of the battery pack are molded as an integrated metal structure, which allows heat to be efficiently transferred from the heat absorption fins to the cylindrical portion. In addition, by molding multiple rows of heat absorption fins integrally with the cylindrical portion, the rigidity of the entire heat dissipation case is increased, which has the advantage of allowing the core block stored inside to be stably held.

[0016] In another embodiment of the battery pack of the present invention, the heat absorption fins are connected to a closing portion, and the closing portion is connected to a cylindrical portion, with the heat absorption fins being arranged at a thermal coupling position on the inner surface of the cylindrical portion via the closing portion.

[0017] In the battery pack described above, the cylindrical portion and the heat-absorbing fins are separate components, so the heat-absorbing fins can be inserted into the cylindrical portion, the closing portion fixed to the cylindrical portion, and the heat-absorbing fins can be thermally coupled to the cylindrical portion and positioned in a predetermined position. Battery packs that can be assembled in this manner can be mass-produced inexpensively with a simple cylindrical portion that does not have heat-absorbing fins, and the assembly process can be simplified by smoothly inserting a core block into the cylindrical portion. Furthermore, the structure in which the heat-absorbing fins are connected to the closing portion allows the heat-absorbing fins and the closing portion to be thermally coupled in a favorable manner, ensuring favorable heat conduction from the heat-absorbing fins to the closing portion, thereby achieving the advantage of more efficient heat dissipation.

[0018] In another embodiment of the battery pack of the present invention, the cylindrical portion, heat absorption fins, and closing portion are separate components, and multiple rows of heat absorption fins are connected to each other to form a fin unit. The fin unit is inserted into the cylindrical portion and connected to the inner surface of the cylindrical portion in a thermally coupled state.

[0019] The above battery pack can be assembled by inserting a fin unit connecting multiple rows of heat absorption fins into a cylindrical portion and connecting each heat absorption fin to the inner surface of the cylindrical portion in a thermally coupled state, so it has the advantage that multiple rows of heat absorption fins can be easily connected to the inner surface of the cylindrical portion in a thermally coupled state and assembled.

[0020] In another embodiment of the battery pack of the present invention, the heat absorption fins have contact protrusions that come into thermally coupled contact with the inner surface of the cylindrical portion, and the heat absorption fins arranged inside the cylindrical portion are connected in a thermally coupled state to the inner surface of the cylindrical portion via the contact protrusions.

[0021] In the battery pack described above, the heat absorption fins have contact protrusions, and the heat absorption fins are arranged in thermal contact with the inner surface of the cylindrical portion via the contact protrusions, so the heat absorption fins arranged inside the cylindrical portion can be reliably connected to the cylindrical portion in a thermally coupled state. In particular, since the contact protrusions on the heat absorption fins are in contact with the inner surface of the cylindrical portion, the heat absorption fins can be inserted into the cylindrical portion with low resistance.

[0022] In a battery pack according to another embodiment of the present invention, the heat dissipation case forms a duct between the inner surface of the cylindrical portion and the heat absorption fins, through which ejected matter from the battery cells flows.

[0023] The battery pack described above uses heat-absorbing fins on the wall surface that forms the duct, and has a duct between the duct and the inner surface of the cylindrical portion, which has the advantage of being able to guide high-temperature, high-pressure exhaust gases and other ejections that are emitted when a battery cell experiences thermal runaway into the duct, preventing thermal runaway from occurring in other battery cells. This is because the ejections from a thermal runaway battery cell can be guided into the duct, preventing the heating of other battery cells. Furthermore, a battery pack with this structure has the advantage of being able to discharge exhaust gases to the outside by connecting the duct to an exhaust opening in the casing, more effectively preventing thermal runaway from occurring.

[0024] In a battery pack according to another embodiment of the present invention, the heat dissipation case has a duct provided at an opposing position on the inside of the cylindrical portion in a cross-sectional shape.

[0025] The above battery pack has a feature in that the cylindrical portion of the heat dissipation case is equipped with ducts at opposing positions inside, and a core block that discharges exhaust gases and other ejected materials on both sides is built into the cylindrical portion, smoothly guiding the ejected material from a thermally runaway battery cell into the duct, thereby preventing the induction of thermal runaway.

[0026] In a battery pack according to another embodiment of the present invention, the cross-sectional shape of the heat dissipation case is such that three or more ducts are provided along the inner surface of the cylindrical portion.

[0027] In the above battery pack, the cylindrical part of the heat dissipation case has three or more ducts along the inner surface, which allows exhaust gases and other ejected materials emitted from the battery cells housed in the core block to be smoothly guided to the nearest duct and efficiently discharged, thereby preventing thermal runaway.

[0028] In another embodiment of the battery pack of the present invention, a pair of heat absorption fins are arranged opposite each other with a slit interposed between them, and the pair of heat absorption fins have first side edges that are thermally coupled to the inner surface of the cylindrical portion, and second side edges that form the opening edge of the slit.

[0029] In the battery pack described above, a pair of heat-absorbing fins are positioned opposite each other with a slit between them. Therefore, exhaust gases and other ejected material from the battery cells pass through the slit and collide with the inner surface of the cylindrical section, where their energy is attenuated and they are split into two parts and flow into their respective ducts. This effectively prevents thermal runaway from being triggered by high-temperature, high-pressure ejected material from a thermally runaway battery cell. In particular, exhaust gases that pass through the slit and are split into two parts to change direction are prevented from flowing to other battery cells, effectively preventing thermal runaway from being triggered.

[0030] In a battery pack according to another embodiment of the present invention, the cylindrical portion has a ridge portion extending along the slit on the surface facing the slit.

[0031] The battery pack described above has the advantage that ejected material that passes through the slit collides with the ridges, and is quickly diverted along the inner surface of the cylindrical portion to both sides by the ridge surface, allowing it to be divided and flow into the duct.

[0032] In another embodiment of the battery pack of the present invention, both the inner surface of the cylindrical portion and the heat absorption fins are arched. The duct has a curved shape, and is gradually narrowed towards both side edges.

[0033] In a battery pack according to another embodiment of the present invention, the heat dissipation case is an integrally formed metal body in which the cross-sectional shape of all areas is the same.

[0034] The battery pack described above has the advantage that the heat dissipation case, which is made of a metal such as aluminum and has an integral structure of a cylindrical portion and heat-absorbing fins, can be efficiently mass-produced.

[0035] In a battery pack according to another embodiment of the present invention, the cylindrical portion is formed into a cylindrical shape by extrusion or drawing. The battery pack has an advantage that the cylindrical portion can be mass-produced at low cost.

[0036] In a battery pack according to another embodiment of the present invention, the heat dissipation case is made of aluminum or magnesium.

[0037] A battery pack according to another embodiment of the present invention includes a plurality of heat dissipation rods disposed between the heat absorption fins and the battery cells, and extending in the axial direction of the cylindrical portion.

[0038] The battery pack described above has the advantage that it can more effectively prevent thermal runaway because it can absorb the heat energy of the heat-generating battery cells with both the heat dissipation rod and the heat absorption fins.

[0039] In a battery pack according to another embodiment of the present invention, the heat dissipation rod and the heat absorption fin are arranged in thermal coupling.

[0040] The battery pack described above has the advantage that the heat energy absorbed by the heat dissipation rod can be efficiently dissipated from the cylindrical portion to the outside via the heat absorption fins, thereby enabling more effective heat dissipation from the battery cells.

[0041] In a battery pack according to another embodiment of the present invention, the heat dissipation rod also serves as a fastening member formed by connecting a pair of closing portions.

[0042] In a battery pack according to another embodiment of the present invention, the heat-absorbing fins also serve as fastening members formed by connecting a pair of closing portions.

[0043] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to these. Furthermore, this specification in no way specifies the components set forth in the claims as components of the embodiments. The dimensions, materials, shapes, and relative positions of components described in the embodiments are not intended to limit the scope of the present invention, and are merely illustrative unless otherwise specified. The size and relative positions of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present invention may be configured with the same components, so that one component serves multiple functions, or conversely, the function of one component may be shared by multiple components. Furthermore, the content described in some examples and embodiments may be applicable to other examples and embodiments.

[0044] The battery pack of the present invention is primarily mounted on an electric vehicle to supply power to the drive motor. It can be used, for example, as a power source for power-assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric carts. However, the present invention does not specify the use of the battery pack, and it can also be used as a power source for various electrical devices used indoors and outdoors, such as cleaners and power tools.

[0045] (Embodiment 1) A battery pack according to a first embodiment of the present invention is shown in FIGS. 1 and 2. FIG. 1 is a schematic side end view of the battery pack, and FIG. 2 is a schematic exploded perspective view of the battery pack. The battery pack 100 shown in these figures includes a battery core block 10 in which multiple battery cells 1 are arranged in fixed positions in a battery holder 2, and a casing 3 that houses the core block 10. The casing 3 includes a heat dissipation case 4 that is open at both ends and inside which the core block 10 is arranged, and a closing section 5 that closes both end openings of the heat dissipation case 4. The closing section 5 is fixed with fastening members 8 at positions that close both end openings of the heat dissipation case 4. The battery pack 100 in FIG. 2 houses a core block 10 in the casing 3, which is made up of multiple battery blocks 9 stacked in the axial direction of the heat dissipation case 4.

[0046] (Core Block 10) As shown in Figures 1 and 2, the core block 10 includes a battery block 9 in which multiple battery cells 1 are arranged in multiple rows and columns in a battery holder 2. The core block 10 shown in Figure 2 includes two sets of battery blocks 9 stacked in the longitudinal direction of the battery cells 1 and connected in a straight line. This core block 10 connects multiple battery cells 1 in parallel to increase the battery charge / discharge capacity (Ah), and connects multiple battery cells 1 in series to increase the output voltage (V). Although the core block 10 shown in the figure includes multiple battery blocks 9, the core block can also be configured with a single battery block. Furthermore, a core block with multiple battery blocks can also be configured with three or more sets of battery blocks.

[0047] (Battery block 9) 1 and 2, each battery block 9 has a battery holder 2 provided with a cylindrical insertion portion 21 for the battery cells 1, and the battery cells 1 are inserted into the cylindrical insertion portion 21 to arrange the battery cells 1 in fixed positions. In the battery block 9, multiple rechargeable battery cells 1 are arranged in multiple rows and columns in the battery holder 2.

[0048] The battery cell 1 is a cylindrical, rechargeable secondary battery, specifically a lithium-ion secondary battery. However, the present invention does not limit the battery cell to lithium-ion batteries, and any other rechargeable secondary battery, such as a nickel-metal hydride battery cell, a nickel-cadmium battery, or a lithium polymer battery, can be used.

[0049] In a battery block 9, multiple battery cells 1 are arranged in parallel with the longitudinal direction of each battery cell 1 facing in the same direction. The multiple battery cells 1 that make up the battery block 9 are connected to the desired number of parallel and series connections using lead plates (not shown) connected to the end surface electrodes on both ends of the battery cells 1, or are connected on a circuit board (not shown). The core block 10 shown in Figure 2 connects two battery blocks 9, each with 10 battery cells 1, for a total of 20 battery cells connected in multiple parallel and multiple series. However, the number and connection form of the battery cells 1 in the core block 10 can be freely changed.

[0050] (Battery holder 2) As shown in Figures 1 and 2, the battery holder 2 is molded from insulating plastic into the same shape and has an insertion tube portion 21 into which the battery cell 1 is inserted. The insertion tube portion 21 holds the battery cell 1 set therein in a fixed position. The battery holder 2 shown in the figures uses cylindrical battery cells 1, and the insertion tube portion 21 is shaped to insert and hold cylindrical batteries in a fixed position. However, the present invention does not necessarily limit the battery cells to cylindrical batteries; the battery cells can also be, for example, prismatic batteries. In a battery pack using prismatic battery cells, the insertion tube portion of the battery holder is prismatic.

[0051] The battery holder 2 in Figure 1 has 10 battery cells 1 arranged in three vertical rows, with the batteries arranged in three rows, four rows, and three rows from top to bottom, in a rice bale-like configuration, with the upper and lower battery cells 1 positioned in the gaps between adjacent battery cells 1 on the left and right.

[0052] As shown in Figures 1 and 2, the battery holder 2 has an insertion tube section 21 into which the battery cells 1 are inserted in a parallel position. The insertion tube section 21 is open at both ends to expose the end electrodes of the cylindrical batteries inserted therein so that lead plates can be connected to the end electrodes. However, the battery holder can also be composed of a pair of cell holders divided into two, or three or more cell holders divided into two.

[0053] Furthermore, the battery pack 100 can also have heat-resistant plates 15 laminated between stacked battery blocks 9, as shown by the dashed lines in Figure 2. Such heat-resistant plates 15 can be made of inorganic materials such as mica, or metal plates. Mica, in particular, has high flame retardancy and non-combustibility, excellent insulation properties, and is relatively inexpensive, making it suitable for components that require heat resistance and insulation. The heat-resistant plates 15, which have excellent heat resistance, will not burn or melt even when exposed to high-temperature exhaust gases or flames emitted from the battery cells 1. This prevents the exhaust gases or flames from penetrating the heat-resistant plates 15 and directly striking the battery cells 1 of the opposing battery block 9.

[0054] (Casing 3) As shown in Figure 2, the casing 3 comprises a heat dissipation case 4 that is open at both ends and a pair of closing sections 5 that close the openings at both ends of the heat dissipation case 4. With the core block 10 inserted into the heat dissipation case 4, the pair of closing sections 5 are fastened with fastening members 8, and both ends of the heat dissipation case 4 are clamped and closed by the pair of closing sections 5 from both sides.

[0055] (heat dissipation case 4) The heat dissipation case 4 has a core block 10 disposed inside, a cylindrical portion 6 formed from metal in a cylindrical shape, and multiple rows of metal heat absorption fins 7 that are thermally bonded to the inner surface of the cylindrical portion 6, protrude inward from the cylindrical portion 6, and are arranged in a position extending in the axial direction of the cylindrical portion 6. The heat dissipation case 4 shown in the figures is formed from metal into an integral structure with the cylindrical portion 6 and the multiple rows of heat absorption fins 7 that protrude from the inner surface of the cylindrical portion 6. However, the heat dissipation case may also have multiple rows of heat absorption fins that are separate members from the cylindrical portion and integrally connected to the inner surface of the cylindrical portion by welding or the like.

[0056] The cylindrical portion 6 shown in the schematic end view of FIG. 1 and the schematic exploded perspective view of FIG. 2 is a cylindrical shape with a pair of opposing plates 6A connected on both sides by side plates 6B, and in cross section, the longitudinal width (W1) is wider than the lateral width (W2). Furthermore, the heat dissipation case 4 has a pair of heat absorption fins 7 extending inward from each opposing plate 6A. The heat dissipation case 4 shown in the figure is made by extrusion or pultrusion molding a metal such as aluminum, forming the heat absorption fins 7 and the cylindrical portion 6 into an integral structure. The heat absorption fins 7 are formed as elongated plates extending from one end of the heat dissipation case 4 to the other, efficiently absorbing thermal energy inside the casing and conducting it to the cylindrical portion 6 for heat dissipation.

[0057] In addition to absorbing and dissipating thermal energy within the casing 3, the heat-absorbing fins 7 also serve as ducts 11 for exhaust gas emitted from the battery cells 1. This heat-dissipating case 4 uses the heat-absorbing fins 7 as ducts 11, and also uses the side plates 6B as ducts 11, so that the ducts 11 for guiding exhaust gas can be formed with a simple shape without the need to mold a dedicated part for forming the duct 11. The heat-dissipating case 4 with the exhaust gas duct 11 inside it can guide high-temperature, high-pressure exhaust gas emitted when a battery cell 1 experiences thermal runaway into the duct 11, preventing it from inducing thermal runaway in other battery cells 1.

[0058] The heat dissipation case 4 shown in Figures 1 and 2 has ducts 11 formed between the inner surface of the tubular portion 6 and the heat absorption fins 7, through which exhaust gas from the battery cells 1 flows. The heat dissipation case 4 shown in the figures has plate-shaped heat absorption fins 7 that extend along the inside of the side plate 6B, and a duct 11 is provided between the side plate 6B and the heat absorption fins 7. A slit 12 is opened between a pair of heat absorption fins 7 connected to each opposing plate 6A. The pair of heat absorption fins 7 are positioned opposite each other with the slit 12 between them. A first side edge of each heat absorption fin 7 is thermally connected to the inner surface of the tubular portion 6, and a second side edge forms the opening edge of the slit 12.

[0059] The slits 12 guide exhaust gas emitted from the battery cells 1 into the duct 11. The opening width of the slits 12 is set to a gap that allows exhaust gas and other ejected matter emitted from the battery cells 1 to be quickly guided into the duct 11. If the opening width of the slits 12 is widened, exhaust gas from the battery cells 1 can flow efficiently into the duct 11, but the amount by which the heat absorption fins 7 protrude from the inner surface of the tubular portion 6 becomes smaller, reducing the surface area of ​​the heat absorption fins 7 and decreasing the heat absorption efficiency. Conversely, if the protrusion amount of the heat absorption fins 7 is increased, the surface area of ​​the heat absorption fins 7 increases and the heat absorption efficiency improves, but the opening width of the slits 12 becomes narrower, making it difficult for the exhaust gas to quickly flow into the duct 11. Therefore, the amount by which the heat absorption fins 7 protrude from the tubular portion 6 and the opening width of the slits 12 are designed to be optimal values ​​taking the above into consideration.

[0060] The slit 12 extends in the axial direction of the cylindrical portion 6 and opens. Because multiple battery blocks 9 are stacked and housed within the heat dissipation case 4, exhaust gas flowing out between the core blocks 10 flows into the duct 11 through the opening of the slit 12, as shown by the arrow in FIG. 1 . The duct 11 is connected to an exhaust opening (not shown) provided in the casing 3, and exhausts the inflowing exhaust gas to the outside. The exhaust opening may be provided in the closing portion 5 or the opposing plate 6A, or in the connecting portion between the closing portion 5 and the heat dissipation case 4, although not shown. The exhaust opening may be provided in the casing 3 as one or multiple through-holes, or may be provided in the casing 3 as a slit. The multiple through-holes or slits provided as exhaust openings may be sealed with a gas-liquid separation membrane or rubber valve that allows gas to pass through but blocks liquids and solids.

[0061] The heat dissipation case 4 in FIG. 1 has an arch-shaped side plate 6B and heat-absorbing fins 7 that curve along the side plate 6B, resulting in a duct 11 that gradually narrows toward both side edges. This heat dissipation case 4 has plate-shaped heat-absorbing fins 7 that extend inward from each opposing plate 6A, positioned in opposing positions. This increases the effective protrusion length of the heat-absorbing fins 7, thereby increasing the heat-absorbing area and enabling efficient absorption of thermal energy generated within the heat dissipation case 4. Furthermore, the heat-dissipation case 4 in FIG. 1 has curved heat-absorbing fins 7, which gradually narrows the inner width of the duct 11 from the slit 12 toward the connecting portion of the opposing plates 6A. This allows exhaust gas to flow into the narrow duct 11, thereby attenuating the energy of high-temperature, high-pressure exhaust gas. This is because the narrow duct 11 creates high resistance to exhaust gas flow, reducing the exhaust gas flow velocity and therefore the kinetic energy of the exhaust gas.

[0062] Furthermore, the heat dissipation case 4 in FIG. 1 has four sets of ducts 11 arranged in an area that includes the four corners on both sides of the cylindrical portion 6, which is roughly rectangular in cross section. Slits 12 are opened between pairs of heat-absorbing fins 7 on both sides of the heat dissipation case 4, and exhaust gas emitted from the battery cells 1 branches off through the slits 12 and flows into the ducts 11 on both sides. A heat dissipation case 4 with this structure causes exhaust gas passing through the slits 12 to collide with the inner surface of the side plate 6B, attenuating its energy and guiding it to the ducts 11 on both sides. This allows the energy of high-temperature, high-pressure exhaust gas forcefully emitted from the battery cells 1 to be attenuated and guided to the ducts 11 for exhaust to the outside. Furthermore, because ducts 11 are provided on both sides of the heat dissipation case 4, a core block 10 that discharges exhaust gas to both sides is built into the cylindrical portion 6 of the casing 3, allowing exhaust gas from a battery cell 1 that has experienced thermal runaway to be smoothly guided to the ducts 11 and discharged to the outside.

[0063] The heat dissipation case 4 shown in Figures 1 and 2 is manufactured by extruding or pultruding metal to form an integral structure of the tubular portion 6 and heat absorption fins 7. Because the heat dissipation case 4 is formed by extruding or pultruding metal through a die to form an integral structure of the tubular portion 6 and heat absorption fins 7, it has the advantage of being able to efficiently mass-produce heat dissipation cases 4 with a uniform cross-sectional shape throughout the entire area using metals such as aluminum. Heat dissipation cases 4 formed by extrusion or pultrusion are preferably formed into an integral structure using aluminum (including aluminum alloys). Aluminum heat dissipation cases 4 have the advantage of being able to efficiently mass-produce using extrusion or pultrusion, as well as the advantage of aluminum's excellent thermal conductivity, which allows for efficient dissipation of thermal energy from battery cells. However, the metal used to form the heat dissipation case 4 is not limited to aluminum; other materials that can be extruded or pultruded to form an integral structure of the tubular portion 6 and heat absorption fins 7, such as magnesium or its alloys, can also be used.

[0064] (Occluded part 5) The closing portion 5 is plate-shaped and closes both end openings of the heat dissipation case 4. Its outer shape conforms to the outer shape of the heat dissipation case 4. The closing portion 5 shown in FIG. 2 has a low peripheral wall 5b along its outer periphery to connect to the opening edge of the heat dissipation case 4 via a fitting structure. The closing portion 5 shown in the figure has a structure in which the inner shape of the peripheral wall 5b conforms to the outer shape of the heat dissipation case 4, allowing the heat dissipation case 4 to be connected while being positioned. However, the closing portion does not necessarily have to have a peripheral wall. It can also be connected while being positioned relative to the heat dissipation case by providing a recess or groove that guides the open end of the heat dissipation case, or by providing a protrusion that is inserted into the opening of the heat dissipation case. By connecting the closing portion 5 to both end openings of the heat dissipation case 4 while positioning it, the outer periphery of the closing portion 5, which is fastened with the fastening members 8, abuts against the open end face of the heat dissipation case 4, thereby accurately closing the casing 3. Furthermore, the closing portion 5 shown in the figure has a through hole 5a through which a fixing screw 14, which will be described later, is inserted.

[0065] Furthermore, although not shown, the closing section 5 can be provided with a discharge connector for discharging the built-in battery cells 1 and a charge connector for charging the built-in battery cells 1. Furthermore, the closing section 5 can also be provided with a display section on its surface that displays the remaining capacity of the battery pack 100. This display section displays the remaining capacity of the battery pack, for example, by lighting a light source such as an LED.

[0066] (Heat dissipation rod 13) Furthermore, the casing 3 shown in the cross-sectional view of Figure 1 has a heat dissipation rod 13 positioned between the battery cells 1 housed in the battery holder 2 and the heat absorption fins 7, extending in the axial direction of the cylindrical section 6. The heat dissipation rod 13 is a metal rod, such as aluminum, inserted into a through-hole 22 in the battery holder 2 and positioned in a fixed position in the core block 10. The heat dissipation rod 13 shown in the figure has both ends thermally connected to the blocking section 5. This allows the thermal energy absorbed by the heat dissipation rod 13 to be thermally conducted to the blocking section 5, thereby dissipating heat more effectively. However, because the heat dissipation rod 13 itself absorbs thermal energy, it absorbs it without being thermally connected to the blocking section 5, thereby suppressing temperature increases. Furthermore, the heat dissipation rod 13 shown in the figure is also used as a fastening member 8 that fastens the blocking section 5 to the heat dissipation case 4. This heat dissipation rod 13 has female threaded holes 13a at both ends into which fixing screws 14 are screwed in to fix it, and the fixing screws 14 that pass through the blocking portion 5 are screwed into the female threaded holes 13a to fix the blocking portion 5 to the heat dissipation case 4.

[0067] (Fastening member 8) The fastening members 8 fasten the pair of closing sections 5 together, sandwiching the heat dissipation case 4 between them. The fastening members 8 fasten the pair of closing sections 5, for example, via a core block 10 housed in the casing 3. The fastening members 8 shown in FIG. 2 are a heat dissipation rod 13 inserted into the battery holder 2 of the core block 10 and a fixing screw 14 that penetrates the closing section 5 and screws into female threaded holes 13a at both ends of the heat dissipation rod 13. However, the fastening members are not limited to the above structure. They can also be fixing screws that penetrate one closing section and the battery core block and screw into the other closing section, or nuts that screw into threaded portions at both ends of a connecting rod that penetrates the pair of closing sections and the battery core block. These fastening members can also be metal rods inserted into through holes in the battery holders of the core block, which also serve as heat dissipation rods.

[0068] Furthermore, the fastening members do not necessarily have to be members that penetrate the core block 10, and for example, the pair of closing portions 5 can also be fastened to the heat dissipation case 4 via the cylindrical portion 6 or the heat absorption fins 7. The fastening members can also be, for example, fixing screws that penetrate the closing portions and are screwed into screw holes provided on the heat absorption fins or cylindrical portion via fixing ribs or bosses.

[0069] Here, the fastening member 8 refers to a member for connecting the pair of closing portions 5 to each other and sandwiching the heat dissipation case 4 from both sides. In a case where the core block 10 is composed of multiple separable battery blocks 9, the fastening member 8 may also include a member for integrally connecting these battery blocks 9. Therefore, an example of the fastening member 8 may be a connector for connecting the multiple battery blocks 9 and a fixture for securing the closing portion 5 to the core block 10. However, in a case where the core block 10 is composed of a single battery block, or in a case where the multiple battery blocks 9 constituting the core block 10 are integrally secured via the battery holder 2, a member for connecting the multiple battery blocks 9 is not necessarily required. In such a case, the connector can be omitted, and the pair of closing portions can be directly secured to the core block. In such a case, the fastening member may be a fixture for securing the closing portion to the core block, such as a fixing screw or rivet.

[0070] (Embodiment 2) Furthermore, the battery pack may also have the structure shown in FIGS. 3 and 4. The heat dissipation case 4 of the battery pack 200 shown in these figures has a cylindrical section 6 with a generally rectangular cross section and both the opposing plate 6A and the side plate 6B being flat. Like the heat dissipation case 4 of the first embodiment, the heat dissipation case 4 of these figures is manufactured by integrally molding the cylindrical section 6 and heat absorption fins 7 using extrusion or pultrusion molding. The heat absorption fins 7 of the heat dissipation case 4 of these figures are formed as plates extending vertically on the inner surface of the opposing plate 6A. The heat absorption fins 7 are arranged parallel to the side plate 6B, forming a duct 11 between the opposing plate 6A and the fins. A slit 12 is provided between the pair of heat absorption fins 7 integrally molded on the opposing opposing plates 6A. The slit 12 guides exhaust gases and other ejected matter emitted from the battery cells 1 to the duct 11. Similar to the casing 3 of the first embodiment, the duct 11 is connected to an exhaust opening and exhausts the incoming exhaust gas to the outside. In the battery pack 200 shown in FIGS. 3 and 4, the blocking portion 5 is omitted.

[0071] Furthermore, the battery pack 200 in Figures 3 and 4 houses multiple battery cells 1 in a horizontal position in the figures, with the multiple battery cells 1 positioned parallel to one another in the longitudinal direction of the cross section of the heat dissipation case 4. The multiple battery cells 1 are arranged in fixed positions via the battery holder 2, with the insertion tube portion 21 in a horizontal position, and are housed in the heat dissipation case 4 as a core block 10. The core block 10 shown in the figures is composed of a set of battery blocks 9. As an example, the battery holder 2 in Figure 4 houses 12 battery cells 1 in two left and right columns and six upper and lower columns. The battery holder 2 is designed to allow exhaust gas emitted from the battery cells 1 to flow through slits 12. The battery cells 1 have exhaust valves at one end for ejecting ejected material, so the ejected material from the battery cells 1 flows from the slits 12 into duct 11 and is discharged to the outside, as shown by the arrows. In a battery pack 200 of this shape, the battery cells 1 eject exhaust gas toward the slits 12 provided between the heat absorption fins 7 (horizontally in the figure), so the exhaust gas can be quickly guided to the duct 11 and discharged to the outside.

[0072] The heat dissipation case 4 shown in Figures 3 and 4 has slits 12 located opposite exhaust valves (not shown) on the end electrodes of the battery cells 1 to facilitate the flow of exhaust gas and other ejected matter from the battery cells 1 into the duct 11. The slits 12 preferably open to an area facing part or all of the exhaust valves to facilitate guiding the exhaust gas from the exhaust valves of the battery cells 1. In the battery pack 200 shown in Figure 3, which houses multiple battery cells 1 in two rows, the slits 12 are located midway between the left and right battery cells 1, and have an opening width that allows access to approximately half of the end electrodes of the left and right battery cells 1. As described above, the heat dissipation case 4 is also designed to optimize the amount of protrusion of the heat absorption fins 7 from the tubular portion 6 and the opening width of the slits 12, taking into account the heat absorption efficiency of the heat absorption fins 7 and the exhaust gas discharge efficiency of the slits 12.

[0073] (Embodiment 3) 5 and 6, similar to the battery holder 2 shown in Fig. 4, the battery pack 300 shown in Fig. 5 and 6 has a battery block 9 configured to store multiple battery cells 1 in a horizontal position, and the multiple battery blocks 9 are arranged in the longitudinal direction of the cylindrical portion 6 (the axial direction of the battery cells 1) and stored in the heat dissipation case 4. Note that the closing portion 5 is omitted in the battery pack 300 shown in Fig. 5 and 6.

[0074] The heat dissipation case 4 shown in the figure has heat-absorbing fins 7 arranged between multiple battery blocks 9. The cross section of the tubular portion 6 of the heat dissipation case 4 shown in the figure is approximately rectangular, and is configured to accommodate three battery blocks 9 arranged longitudinally in the cross section. A pair of heat-absorbing fins 7 protruding from the inner surface of the opposing plate 6A is provided between each battery block 9, separating adjacent battery blocks 9. The heat dissipation case 4 forms a gap 25 between the pair of heat-absorbing fins 7. The pair of heat-absorbing fins 7 connects the first side edge to the inner surface of the opposing plate 6A, and the end on the second side edge is bent to form a bent piece 7a, forming a gap 25 between the opposing bent pieces 7a. Furthermore, each heat-absorbing fin 7 forms a duct 11 between the bent piece 7a at the end on the second side edge and the inner surface of the tubular portion 6, allowing the flow of material ejected from the battery cells 1. The pair of heat absorbing fins 7 are arranged point symmetrically in cross section by bending the bent pieces 7a in opposite directions.

[0075] Furthermore, the heat dissipation case 4 shown in the figure is provided with heat-absorbing fins 7 that protrude from the inner surface of the opposing side plate 6B, and a duct 11 is also formed between the side plate 6B and the opposing battery block 9. The heat-absorbing fins 7 that protrude from the inner surface of the side plate 6B connect their first side edge to the inner surface of the side plate 6B, and the tip of the second side edge is bent so that this bent piece 7b is in surface contact with the end surface of the battery block 9. The heat-absorbing fins 7 form a duct 11 between them and the opposing plate 6A to allow material ejected from the battery cells 1 to flow in, and a narrow, dead-end duct 11 is also provided between the side plate 6B and the bent piece 7b.

[0076] Furthermore, as shown by the dotted line in Figure 5, the heat dissipation case 4 can be provided with a sub-heat absorption fin 7S on the end face of the battery holder 2, facing the end face of the battery cell 1 on the exhaust valve side. This sub-heat absorption fin 7S is connected to the opposing plate 6A so that it protrudes vertically. This structure allows a narrow, dead-end duct 11 to be formed between the heat absorption fin 7 and the sub-heat absorption fin 7s, and exhaust gas ejected from the battery cell 1 can flow into the narrow duct 11, thereby reducing the kinetic energy of the exhaust gas. This structure also allows a slit 12 to be formed between the leading edge of the sub-heat absorption fin 7s and the bent pieces 7a, 7b of the heat absorption fin 7, and the opening width of this slit 12 can be adjusted to control the flow of exhaust gas into the duct 11.

[0077] The battery pack 300 shown in the figures also houses multiple battery cells 1 in a horizontal position, parallel to one another in the longitudinal direction in the cross section of the heat dissipation case 4. The multiple battery cells 1 are arranged in a fixed position via a battery holder 2 with the insertion tube portion 21 in a horizontal position, and are housed in the heat dissipation case 4 as a core block 10. Each battery block 9 is arranged so that ejected material from the battery cells 1 flows into a duct 11 provided at an opposing position. Each battery block 9 shown in Figure 6 houses battery cells 1 in two left and right rows and multiple levels, with the upper and lower battery cells 1 facing the same direction. Generally, battery cells 1 have a discharge valve on one end electrode (the protruding electrode in the figure), and the battery cells 1 are housed so that the end face with the discharge valve is positioned opposite the duct 11 of the heat dissipation case 4. 5, in the battery pack 300, the battery cell 1 located on the upper side in the figure ejects ejected material from the left end face as indicated by the arrow, so a duct 11 is provided in a position opposite this ejection side end face, and the battery cell 1 located on the lower side in the figure ejects ejected material from the right end face as indicated by the arrow, so a duct 11 is provided in a position opposite this ejection side end face. A heat dissipation case 4 with this shape also achieves the advantage of being able to effectively dissipate the thermal energy of ejected material such as exhaust gases, thanks to the multiple heat absorption fins 7 protruding from the inner surface of the cylindrical portion 6.

[0078] (Embodiment 4) Furthermore, the battery pack 400 shown in FIGS. 7 and 8 has a structure in which multiple heat-absorbing fins 7 are separate from the cylindrical portion 6 and connected to the closing portion 5. The heat-absorbing fins 7 shown in the figures are composed of four curved plates arranged along the four corners of the core block 10. Both ends of the four curved plates are connected to a pair of closing portions 5 via fixing screws 14 that pass through the closing portions 5. In this battery pack 400, by connecting the closing portions 5 to the cylindrical portion 6, the heat-absorbing fins 7 are arranged at thermally coupled positions on the inner surface of the cylindrical portion 6 via the closing portions 5. The heat-absorbing fins 7, which are curved plates, have a first side edge that is thermally coupled to the inner surface of the cylindrical portion 6 and a second side edge that is spaced apart from the inner surface of the cylindrical portion 6, with a slit 12 formed between the opposing second side edges. A duct 11 is formed between the pair of heat-absorbing fins 7 that form the slit 12 and the inner surface of the cylindrical portion 6.

[0079] Furthermore, the heat-absorbing fins 7 shown in the figures are thermally coupled to the heat-dissipating rods 13 that are inserted into through-holes 22 in the battery holder 2. The heat-absorbing fins 7 shown in the figures have a curved shape that extends in the axial direction of the tubular portion 6 along the four corners of the battery holder 2, and are integrally molded to connect the heat-dissipating rods 13 that are inserted into the through-holes 22 in the battery holder 2. The heat-absorbing fins 7 shown in Figure 7 are integrally connected to the heat-dissipating rods 13 via connecting portions 16. To insert the heat-dissipating rods 13 connected to the heat-absorbing fins 7 into the through-holes 22, the battery holder 2 has insertion slits 23 that guide the connecting portions 16 by partially cutting out the peripheral wall of the through-holes 22 in the axial direction.

[0080] The structure described above, which integrally connects the heat absorption fins 7 and the heat dissipation rod 13, allows the heat absorption fins 7 to be positioned in a fixed position on the battery holder 2 by inserting the heat dissipation rod 13 into the through-hole 22 of the battery holder 2. This allows multiple heat absorption fins 7 to be connected to the closure 5 while positioned in their fixed positions. The casing 3 shown in the figure is configured so that fixing screws 14 are threaded into female threaded holes 17 on both ends of the heat absorption fins 7. The female threaded holes 17 are formed by connecting a cylindrical body 24 to the outer surface of the heat absorption fins 7 by welding or other means. Although not shown, the heat absorption fins can also be provided with thickened or protruding portions and female threaded holes drilled into their end surfaces. However, one end of the heat absorption fins 7 can also be fixed to the closure 5 by welding or other means. In this structure, four heat absorption fins 7 are fixed in their fixed positions on the closure 5, and a core block 10 is placed between the heat absorption fins 7 fixed to the closure 5 for thermal coupling. As described above, the structure connecting the blocking portion 5 to the heat absorption fin 7 has the advantage that the thermal energy absorbed by the heat absorption fin 7 can be effectively dissipated by making all or part of the blocking portion 5 (for example, the part to which the heat absorption fin 7 is connected) out of metal.

[0081] The battery pack 400 shown in the figures has a structure in which the heat dissipation rod 13 is thermally coupled to the heat absorption fins 7, so that the thermal energy of the heat-generating battery cells 1 is efficiently absorbed by the heat dissipation rod 13. The heat dissipation rod 13 itself absorbs thermal energy to suppress temperature increases in the battery cells and exhaust gases, but by being thermally coupled to the heat absorption fins 7, the absorbed thermal energy is thermally conducted to the tubular portion 6 and the closed portion 5 via the heat absorption fins 7, allowing for more effective dissipation to the outside.

[0082] Furthermore, in the battery pack 400, the heat absorption fins 7, which are thermally coupled to the core block 10, are inserted into the cylindrical portion 6 together with the core block 10 and are thermally coupled to the inner surface of the cylindrical portion 6. After the core block 10 to which the heat absorption fins 7 are coupled is inserted into the cylindrical portion 6, the other closing portion 5 is fixed to the tip of the heat absorption fin 7, and both ends of the cylindrical portion 6 are closed by the pair of closing portions 5. The heat absorption fins 7 are fixed to the closing portions 5 by threading fixing screws 14 that pass through the closing portions 5 into female threaded holes 17 provided at both ends of the heat absorption fin 7, and these also serve as fastening members 8 that close both end openings of the heat dissipation case 4 with the pair of closing portions 5. However, the heat absorption fins do not necessarily have to be directly fixed to the closing portions. Female threaded holes can be provided at both ends of a heat dissipation rod connected to the heat absorption fins, and the heat dissipation rod can be fixed to the closing portions via fixing screws that are threaded into the female threaded holes.

[0083] In the battery pack 400 described above, the cylindrical portion 6 and the heat absorption fins 7 are separate members, so by fastening the blocking portion 5 to the cylindrical portion 6 with the heat absorption fins 7 inserted into the cylindrical portion 6, the heat absorption fins 7 can be arranged in a predetermined position on the cylindrical portion 6 in a thermally coupled state. The battery pack 400 that can be assembled in this state can be mass-produced inexpensively with a simple cylindrical portion 6 that does not have the heat absorption fins 7, and the assembly process can be simplified by smoothly inserting the core block 10 into the cylindrical portion 6. Furthermore, the structure in which the heat absorption fins 7 are connected to the blocking portion 5 connects the heat absorption fins 7 and the blocking portion 5 in a favorable thermally coupled state, which also favors heat conduction from the heat absorption fins 7 to the blocking portion 5, thereby realizing the advantage of more efficient heat dissipation.

[0084] (Embodiment 5) 9, similarly to the battery pack 400 shown in the fourth embodiment, the battery pack 500 shown in FIG. 9 has a structure in which the heat absorption fins 7 are separate members from the cylindrical portion 6 and connected to the closing portion 5, and also has a duct 11 provided between the facing plate 6A of the cylindrical portion 6 and the heat absorption fins 7. The heat dissipation case 4 shown in FIG. 9 has a first side edge of the heat absorption fins 7 arranged inside the cylindrical portion 6 not in contact with the inner surface of the cylindrical portion 6, and the end of the first side edge is positioned away from the facing plate 6A, thereby providing a duct 11 between the facing plate 6A and the heat absorption fins 7.

[0085] The heat absorption fin 7 in the figures has a contact protrusion 19 extending in the axial direction in the middle portion, and this contact protrusion 19 is thermally connected to the inner surface of the tubular portion 6. As shown in Figure 10, the contact protrusion 19 in the figures is a columnar protrusion 19A extending to both ends of the heat absorption fin 7, and this protrusion 19A is integrally connected to the heat absorption fin 7 so as to protrude outward from the surface. In the figure, the contact protrusion 19 is arranged in contact with the inner surface of the opposing plate 6A of the tubular portion 6 and is thermally connected to the tubular portion 6. The heat absorption fin 7 is thermally connected to the tubular portion 6 via the contact protrusion 19 provided on the outside of the middle portion, and the end on the first side edge is positioned away from the opposing plate 6A with a duct 11 provided therebetween, and the end on the second side edge is positioned away from the side plate 6B with a duct 11 provided therebetween. A slit 12 is provided in the center of the inner surface of the opposing plate 6A between the first side edges of adjacent heat-absorbing fins 7. In the cross section of a heat dissipation case 4 with this structure, ducts 11 are provided on the inside of the side plates 6B, which are both longitudinal ends, and also on the inside of the opposing plate 6A, which extends in the longitudinal direction. In this way, a structure with four ducts 11 provided along the four sides of the heat dissipation case 4 allows ejected material from the battery cells 1 to flow into the ducts 11 through nearby slits 12, allowing it to be quickly discharged to the outside, effectively suppressing thermal damage caused by ejected material such as high-temperature, high-pressure exhaust gases.

[0086] The contact protrusions 19 shown in Fig. 10 are formed in a columnar shape extending in the axial direction of the heat absorption fin 7, and are in contact with and thermally bonded to the inner surface of the tubular portion 6 in an area extending in the axial direction. Furthermore, the contact protrusions 19 shown in the figure have female threaded holes 17 drilled on both end surfaces, and the blocking portions 5 can be connected by screwing fixing screws 14 into these female threaded holes 17. In other words, the contact protrusions 19 also serve as fastening members 8 that close the openings at both ends of the heat dissipation case 4 with the pair of blocking portions 5. The contact protrusions shown in the figure are formed integrally with the heat absorption fins by extrusion or drawing, but the contact protrusions can also be formed by connecting a columnar metal rod or metal pipe to the surface of the heat absorption fin by welding or the like.

[0087] The contact protrusions 19 shown in Figures 9 and 10 are ribs 19A with a cylindrical cross section. This allows for smooth insertion of the heat absorption fins 7 connected to the core block 10 into the cylindrical portion 6 by reducing contact resistance with the inner surface of the cylindrical portion 6. However, the cross section of the contact protrusions 19 can be modified to various columnar shapes. In this case, the shape can be made to connect to the inner surface of the cylindrical portion 6 in a surface-to-surface contact state, allowing for efficient heat conduction. Furthermore, regardless of the shape of the ribs 19A, thermally conductive grease can be applied between the ribs 19A and the cylindrical portion 6, or a thermally conductive sheet can be sandwiched between the two surfaces to improve contact with the inner surface of the cylindrical portion 6 and improve heat transfer from the heat absorption fins 7 to the cylindrical portion 6.

[0088] In the battery pack 500 described above, the heat-absorbing fins 7 are inserted into the cylindrical portion 6, closing the pair of closing portions 5 at both end openings of the heat dissipation case 4. The contact protrusions 19 of the heat-absorbing fins 7 are in contact with the inner surface of the cylindrical portion 6, and the heat-absorbing fins 7 are arranged in a thermally coupled state. The ducts 11 are formed between the opposing plate 6A and the side plate 6B of the cylindrical portion 6 and the heat-absorbing fins 7. This battery pack 500 simplifies the assembly process by mass-producing the cylindrical portion 6 inexpensively and smoothly inserting the heat-absorbing fins 7 and core block 10 into the cylindrical portion 6. Furthermore, connecting the cylindrical portion 6 and the heat-absorbing fins 7 in a thermally coupled state via the contact protrusions 19 ensures favorable heat conduction from the heat-absorbing fins 7 to the cylindrical portion 6, enabling more efficient heat dissipation. Furthermore, providing ducts 11 on all four sides of the cylindrical portion allows for ideal guidance of ejected material to the ducts 11 for heat dissipation, regardless of the position of the battery cell 1 experiencing thermal runaway.

[0089] (Embodiment 6) 11, the cylindrical portion 6, the heat absorption fins 7, and the closing portion 5 are separate components. The casing 3 shown in the figure has multiple rows of heat absorption fins 7 connected to each other by connecting portions 18 to form a fin unit 20. This fin unit 20 is inserted into a fixed position in the cylindrical portion 6, and the multiple heat absorption fins 7 are connected to the cylindrical portion 6 in a thermally coupled state.

[0090] The fin unit 20 shown in the figure has an integrated structure in which four heat absorption fins 7 are arranged along the outer sides of the four corners of the core block 10 and connected to each other at the top and bottom by connecting portions 18. Each heat absorption fin 7 has a first side edge thermally coupled to the inner surface of the cylindrical portion 6 and a second side edge spaced apart from the inner surface of the cylindrical portion 6, with a slit 12 formed between the opposing second side edges. A duct is formed between the pair of heat absorption fins 7 forming the slit 12 and the inner surface of the cylindrical portion 6. The fin unit 20 shown in the figure has contact protrusions 19 on each heat absorption fin 7 that thermally contact the inner surface of the cylindrical portion 6. The fin unit 20 shown in the figure has multiple dome-shaped protrusions 19B on the outer surface of the heat absorption fin 7 in the area facing the inner surface of the cylindrical portion 6, forming the contact protrusions 19. The multiple protrusions 19B are arranged at equal intervals extending in the axial direction of the cylindrical portion 6. The protrusions 19B are formed, for example, by stamping the heat-absorbing fins 7 from the inner surface side, into a dome shape that protrudes outward. When the fin unit 20 is inserted into the cylindrical portion 6, the contact protrusions 19 consisting of multiple protrusions 19B are thermally coupled to the inner surface of the cylindrical portion 6. Furthermore, by providing the contact protrusions 19 on the surface of the fin unit 20, the fin unit 20 can be inserted into the cylindrical portion 6 with low resistance. Furthermore, although not shown, it is also possible to apply thermally conductive grease between the protrusions 19B and the cylindrical portion 6, or to sandwich a thermally conductive sheet that improves heat transfer between the two surfaces.

[0091] The above battery pack 600 has the advantage that the fin unit 20 connecting multiple rows of heat absorption fins 7 can be inserted into the cylindrical portion 6, and each heat absorption fin 7 can be connected in a thermally coupled state to the inner surface of the cylindrical portion 6, so that the multiple rows of heat absorption fins 7 can be easily assembled while being thermally coupled to the inner surface of the cylindrical portion 6.

[0092] (Embodiment 7) 12, multiple rows of heat absorption fins 7 are arranged on the inner surface of the cylindrical portion 6 between the cylindrical portion 6 and the core block 10 inserted into the cylindrical portion 6. Each heat absorption fin 7 is integrally molded to protrude from the inner surface of the cylindrical portion 6 and is arranged along the outer peripheral surface of the core block 10.

[0093] In a cross-sectional view, the heat dissipation case 4 shown in the figure has multiple heat absorption fins 7 arranged opposite the outer surface of the insertion cylindrical portion 21 that houses the battery cells 1 arranged on the outer periphery of the battery holder 2. In the figure, the heat absorption fins 7 arranged on both sides of the opposing plate 6A and on the side plate 6B are V-shaped in plan view, and are configured to contact the outer surface of the insertion cylindrical portion 21 in two directions. In addition, the heat absorption fin 7 arranged in the center of the opposing plate 6A is T-shaped in plan view, and is configured to contact the outer surface of the insertion cylindrical portion 21 in one direction. The heat dissipation case 4 shown in the figure has three V-shaped heat absorption fins 7 arranged on each side, and one T-shaped heat absorption fin 7 arranged on each top and bottom.

[0094] Furthermore, the heat dissipation case 4 has slits 12 formed between the leading edges of adjacent heat absorption fins 7, and ducts 11 formed between the pair of heat absorption fins 7 forming the slits 12 and the inner surface of the tubular portion 6. The heat dissipation case 4 shown in the figure has two rows of ducts 11 on the inner side of each of the pair of opposing plates 6A, and two rows of ducts 11 on the inner side of each of the pair of opposing plates 6A, for a total of eight rows of ducts 11 along the inner side of the tubular portion 6. This heat dissipation case 4 is designed to allow exhaust gas and other ejected matter emitted from the battery cells 1 to pass through the slits 12 and flow into the ducts 11.

[0095] Furthermore, the cylindrical portion 6 shown in the figure has ridges 6a extending along the slits 12 on the surface facing the slits 12, and as shown by the arrows in the figure, exhaust gas that passes through the slits 12 collides with the ridges 6a and is quickly divided to both sides and flows into the duct 11. The battery pack 700 with the above structure has the advantage of being able to dissipate heat more effectively by quickly directing the ejected material from the battery cells 1 into the nearest duct 11, as shown by the arrows in the figure. [Industrial Applicability]

[0096] The battery pack according to the present invention is attached to an electric vehicle and supplies power to a drive motor, and can be suitably used as a power source for, for example, an electric motor-assisted bicycle, an electric motorcycle, an electric wheelchair, an electric tricycle, an electric cart, etc. [Explanation of symbols]

[0097] 100, 200, 300, 400, 500, 600, 700... Battery packs 1...Battery cell 2...Battery holder 3...Casing 4...Heat dissipation case 5...Occluded area 5a...Through hole 5b...peripheral wall 6...Cylinder part 6A...opposing plate 6B...Side plate 6a…Yamabe 7...Heat absorption fin 7S...Sub heat absorption fin 7a, 7b...bent piece 8...Fastening member 9...Battery block 10...Core block 11...Duct 12...Slit 13...Heat dissipation rod 13a...Female screw hole 14...Fixing screw 15...Heat-resistant plate 16...Connection part 17...Female screw hole 18...Connection part 19...Contact protrusion 19A…Convex strip 19B...Convex part 20...Fin unit 21...insertion tube 22...Through hole 23...Insertion slit 24...Cylinder 25...opposing gap 90...Core block 92...Battery holder 93...Casing 94...Heat dissipation case 94a...Fixed rib 94c...screw hole 95...Occluded part 96...Set screw 97...Gasket

Claims

1. a battery core block formed by arranging a plurality of battery cells in fixed positions in a battery holder; a casing that houses the core block, The casing is a heat dissipation case having openings at both ends; and a closing portion that closes both end openings of the heat dissipation case, The heat dissipation case is a cylindrical portion in which the core block is disposed inside and which is formed by molding a metal into a cylindrical shape; a plurality of rows of heat-absorbing fins made of metal, thermally coupled to the inner surface of the cylindrical portion, protruding inward from the cylindrical portion, and arranged in a position extending in the axial direction of the cylindrical portion; A battery pack comprising:

2. 2. The battery pack according to claim 1, The battery pack according to claim 1, wherein the heat dissipation case is formed by molding the cylindrical portion and the heat absorption fins into an integral structure using metal.

3. 2. The battery pack according to claim 1, The heat absorption fin is connected to the closing portion, The battery pack according to claim 1, wherein the closing portion is connected to the cylindrical portion, and the heat-absorbing fins are disposed at thermally coupled positions on the inner surface of the cylindrical portion via the closing portion.

4. 2. The battery pack according to claim 1, The cylindrical portion, the heat absorption fin, and the closing portion are separate members, A plurality of rows of the heat absorption fins are connected to each other to form a fin unit, The battery pack is characterized in that the fin unit is inserted into the cylindrical portion and is connected to the inner surface of the cylindrical portion in a thermally coupled state.

5. 5. The battery pack according to claim 3, the heat absorption fin has a contact protrusion that contacts the inner surface of the cylindrical portion in a thermally coupled state; The battery pack according to claim 1, wherein the heat-absorbing fins arranged inside the cylindrical portion are thermally coupled to the inner surface of the cylindrical portion via the contact protrusions.

6. 6. The battery pack according to claim 1, a heat dissipation case that forms a duct between the inner surface of the cylindrical portion and the heat absorption fins to allow ejected material from the battery cells to flow therein;

7. 7. The battery pack according to claim 6, The battery pack according to claim 1, wherein the heat dissipation case has a cross-sectional shape in which the duct is provided at an opposing position on the inside of the cylindrical portion.

8. 7. The battery pack according to claim 6, a heat dissipation case having a cross-sectional shape in which three or more ducts are provided along the inner surface of the cylindrical portion;

9. 9. The battery pack according to claim 6, wherein: The pair of heat-absorbing fins are arranged opposite to each other with a slit interposed therebetween, The pair of heat-absorbing fins have first side edges that are thermally coupled to the inner surface of the cylindrical portion, and second side edges that form opening edges of the slits.

10. 10. The battery pack according to claim 9, The battery pack according to claim 1, wherein the cylindrical portion has a ridge portion extending along the slit on a surface facing the slit.

11. 11. The battery pack according to claim 6, The battery pack is characterized in that both the inner surface of the cylindrical portion and the heat absorption fins are curved in an arch shape, and the duct has a shape that gradually narrows toward both side edges.

12. 12. The battery pack according to claim 1, The battery pack is characterized in that the heat dissipation case is a metal molded body of an integral structure in which the cross-sectional shape of all areas is the same.

13. 13. The battery pack of claim 12, The battery pack is characterized in that the cylindrical portion is an extruded or drawn cylindrical portion.

14. 14. The battery pack of claim 13, The battery pack is characterized in that the heat dissipation case is made of aluminum or magnesium.

15. 15. The battery pack according to claim 1, The battery pack further comprises a plurality of heat dissipation rods disposed between the heat absorption fins and the battery cells, the heat dissipation rods extending in the axial direction of the cylindrical portion.

16. 16. The battery pack of claim 15, The battery pack is characterized in that the heat dissipation rod and the heat absorption fin are arranged in a thermally coupled state.

17. 17. The battery pack according to claim 15 or 16, The battery pack according to claim 1, wherein the heat dissipation rod also serves as a fastening member connecting a pair of the closing portions.

18. 18. The battery pack according to claim 1, The battery pack according to claim 1, wherein the heat absorbing fins are also used as fastening members that connect the pair of closing portions.

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