Battery pack

Abstract

In the present invention, harmful effects due to high-temperature discharge gas ejected from unit cell discharge-valves are suppressed.　In an outer case (9), a battery pack accommodates battery blocks (10), in which a plurality of unit cells (1) having discharge valves are arranged and fixed in position by a battery holder (2), by coupling heat-resistant caps (5) to end portions of the battery blocks and coupling a circuit board (4) to a first surface (10A) of the battery blocks. The heat-resistant caps (5) are each provided with: an occluding plate section (5X) that forms a first discharge gap (11A) between itself and an end surface (10X) of the battery block (10); and a peripheral wall section (5A) that forms a second discharge gap between itself and the first surface (10A) of the battery block (10). The circuit board (4) is disposed so as to create a ventilating gap (12) between itself and the first surfaces (10A) of the battery blocks (10); the ventilating gap (12) communicates with the second discharge gap (11B); and exhaust gas discharged from the discharge valves of the unit cells (1) passes via a discharge gap (11) composed of the first discharge gap (11A) and the second discharge gap (11B), through the ventilating gap (12) and is discharged from a discharge section (15) to the exterior.

Description

[Technical field]

[0001] The present invention relates to a battery pack having a large capacity by connecting a plurality of battery cells in series or in parallel. [Background technology]

[0002] Battery packs, each containing multiple battery cells housed in a case, are used as power sources for portable cordless electrical devices. These battery packs have multiple battery cells connected in series or parallel to increase capacity. In recent years, there has been an increasing demand for higher output from battery packs used as power sources for electrical devices, and non-aqueous electrolyte secondary batteries such as lithium-ion batteries, which have excellent efficiency per unit volume, have been adopted.

[0003] Lithium-ion batteries have high output, but their internal pressure can rise for some reason. To ensure safety against an increase in the battery's internal pressure, a discharge valve is provided that opens at a set pressure to prevent the battery from bursting. When the discharge valve opens, the battery is in an abnormally heated state and high-temperature gas is forcefully ejected from the discharge valve. A battery pack has been developed that has a hole in the exterior case to allow the exhaust gas discharged from the discharge valve to be discharged to the outside. (See Patent Document 1) Furthermore, a battery pack has also been developed in which the exterior case is provided with multiple through holes to improve internal ventilation, promote heat dissipation from the battery, and prevent heat from building up inside the case (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-196039 A [Patent Document 2] Japanese Patent Application Publication No. 10-162795 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional battery packs have holes in the exterior case to allow exhaust gases sprayed from the exhaust valve to be discharged to the outside. With this type of battery pack, it is difficult to safely discharge the high-temperature exhaust gases that are sprayed forcefully from the battery cells. In particular, the exhaust gases sprayed from the exhaust valve of lithium-ion batteries, which are non-aqueous electrolyte secondary batteries, are abnormally hot at over 400°C and are sprayed forcefully, causing the exhaust gas to melt the exterior case. If the high-temperature exhaust gas is sprayed outside the case and ignites, safety is significantly compromised.

[0006] The present invention was developed with the aim of preventing the above-mentioned problems, and its main object is to provide a battery pack that prevents a decrease in safety due to high-temperature exhaust gas being sprayed from an opening exhaust valve. [Means for solving the problem]

[0007] A battery pack according to an embodiment of the present invention includes a battery block in which a plurality of battery cells, each having a discharge valve that opens when the internal pressure exceeds a set pressure, are arranged in a fixed position by a battery holder, a heat-resistant cap connected to an end of the battery block, a circuit board arranged along a first surface adjacent to the end face of the battery block on which the heat-resistant cap is arranged and connected to the battery block, and an exterior case that houses the battery block to which the heat-resistant cap and the circuit board are connected and has an exhaust section that exhausts exhaust gas discharged from the exhaust valve to the outside. The battery block has an exhaust valve side end face on which the exhaust valve of the battery cell is provided arranged at the first end to which the heat-resistant cap is connected. The heat-resistant cap includes a closing plate portion that forms a first exhaust gap between itself and the end face of the battery block, and a peripheral wall portion that is connected to the periphery of the closing plate portion and forms a second exhaust gap between itself and the first surface of the battery block. The circuit board forms a ventilation gap between itself and the first surface of the battery block, and the edge portion on the first end side is laminated to the peripheral wall portion to connect the ventilation gap to the second exhaust gap. The battery pack is configured so that exhaust gas discharged from the exhaust valve of the battery cell passes through the ventilation gap from the exhaust gap consisting of the first exhaust gap and the second exhaust gap, and is exhausted to the outside from the exhaust section. Effect of the Invention

[0008] The battery pack of the present invention can enhance safety by suppressing adverse effects caused by high-temperature exhaust gas ejected from the exhaust valve of the battery cell. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of a battery pack according to an embodiment of the present invention; [Diagram 2] 2 is a vertical cross-sectional view of the battery pack shown in FIG. 1. [Diagram 3] 2 is a vertical cross-sectional view of the battery pack shown in FIG. 1. [Figure 4] FIG. 2 is an exploded perspective view of the battery pack shown in FIG. [Diagram 5] 5 is an exploded perspective view of a core pack of the battery pack shown in FIG. 4. [Figure 6] FIG. 6 is an exploded perspective view of the battery block shown in FIG. 5. [Figure 7] 3 is an enlarged cross-sectional view of a main part of the battery pack shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The battery pack of the first embodiment of the present invention includes a battery block in which a plurality of battery cells, each having a discharge valve that opens when the internal pressure exceeds a set pressure, are arranged in a fixed position by a battery holder, a heat-resistant cap connected to an end of the battery block, a circuit board arranged along a first surface adjacent to the end face of the battery block on which the heat-resistant cap is arranged and connected to the battery block, and an exterior case that houses the battery block to which the heat-resistant cap and the circuit board are connected and has an exhaust section that exhausts exhaust gas discharged from the exhaust valve to the outside. The battery block has an exhaust valve side end face on which the exhaust valve of the battery cell is provided arranged at the first end to which the heat-resistant cap is connected. The heat-resistant cap includes a closing plate portion that forms a first exhaust gap between itself and the end face of the battery block, and a peripheral wall portion that is connected to the periphery of the closing plate portion and forms a second exhaust gap between itself and the first surface of the battery block. The circuit board is arranged so that a ventilation gap is formed between the circuit board and the first surface of the battery block, and the edge portion on the first end side is laminated to the peripheral wall portion so that the ventilation gap is communicated with the second exhaust gap. In the battery pack, exhaust gas discharged from the exhaust valve of the battery cell passes through the ventilation gap from the exhaust gap consisting of the first exhaust gap and the second exhaust gap, and is exhausted to the outside from the exhaust section.

[0011] The above battery pack can eliminate the adverse effects of high-temperature exhaust gas injected from the open exhaust valve and ensure high safety. This is because the above battery pack passes the high-temperature exhaust gas injected from the exhaust valve from the exhaust gap formed between the first end of the battery block and the heat-resistant cap to the ventilation gap formed between the first surface of the battery block and the circuit board, and exhausts it to the outside from the exhaust section 15. This battery pack guides the high-temperature exhaust gas discharged from the exhaust valve from the first exhaust gap to the second exhaust gap, and further guides it from the second exhaust gap to the ventilation gap, passes it through the ventilation gap, and then exhausts it to the outside from the exhaust section of the exterior case. This structure causes the high-temperature, high-energy exhaust gas injected from the exhaust valve to collide with the closing plate section of the heat-resistant cap to attenuate its energy, and then passes the exhaust gas with attenuated energy in the first exhaust gap from the second exhaust gap to the ventilation gap to attenuate its energy. In particular, exhaust gas passing through the ventilation gap loses both kinetic and thermal energy as it collides with various components on the battery holder and circuit board as it passes through the ventilation gap, thereby effectively attenuating the kinetic and thermal energy of the high-temperature exhaust gas discharged from the exhaust valve and eliminating the harmful effects of high-temperature exhaust gas.

[0012] In a battery pack according to a second embodiment of the present invention, a heat-resistant cap is connected to the periphery of the closing plate portion and includes a sub-peripheral wall portion connected to the outer circumferential surface of the battery block.

[0013] With the above configuration, the heat-resistant cap has a sub-circumferential wall portion that is connected to the outer peripheral surface of the battery block, so the heat-resistant cap can be securely connected to the end of the battery block while effectively preventing exhaust gas from leaking to surfaces other than the first surface of the battery block. In particular, it is possible to effectively prevent high-temperature exhaust gas discharged from the exhaust valve from being directly sprayed onto the inner surface of the exterior case and causing damage thereto.

[0014] In a battery pack according to a third embodiment of the present invention, a heat-resistant cap is disposed between end faces of adjacent battery cells and includes a partition wall that defines a first discharge gap at each end face of the battery cells.

[0015] According to the above configuration, a partition is provided between the end faces of adjacent battery cells on the battery block end face side of the blocking plate, and this partition divides the first exhaust gap into each end face of each battery cell. The exhaust gas discharged to the valve side end face of the battery cell is exhausted by passing it through the first exhaust gap and the second exhaust gap, thereby preventing the induction of thermal runaway in the battery cell and attenuating both the kinetic energy and thermal energy of the exhaust gas before exhausting it to the outside.

[0016] In a battery pack of a fourth embodiment of the present invention, the outer case includes a surface plate portion facing the circuit board, and an expansion gap for exhaust gas is formed between the surface plate portion and the circuit board, and exhaust gas that has passed through the ventilation gap is passed through the expansion gap and exhausted to the outside from the exhaust portion.

[0017] According to the above configuration, the exhaust gas that has passed through the ventilation gap is passed through the expansion gap formed between the circuit board and the surface plate portion of the outer case and exhausted to the outside from the exhaust section, so that the exhaust gas whose energy has been attenuated by passing through the ventilation gap can have its energy further attenuated in the expansion gap before being exhausted to the outside.

[0018] In a battery pack according to a fifth embodiment of the present invention, the exterior case has an exhaust section provided in the surface plate section at the end opposite the first end of the battery block.

[0019] With the above configuration, the exhaust section is provided on the surface plate at the end of the exterior case facing the first end of the battery block, and the energy of the exhaust gas discharged from the exhaust section can be reliably attenuated. With this structure, the first end of the battery block, where the exhaust valves of the battery cells are located, and the exhaust section provided on the surface plate are located close to each other, and the exhaust gas is diverted into the ventilation gap, so that the energy of the exhaust gas can be reliably attenuated and discharged.

[0020] In a battery pack according to a sixth embodiment of the present invention, the heat-resistant cap is made of reinforced plastic that is reinforced by embedding an inorganic material in the resin.

[0021] In a battery pack according to a seventh embodiment of the present invention, the battery cells are cylindrical batteries, and the end faces of multiple cylindrical batteries are arranged on the same plane and in a parallel position in a battery holder to form a battery block.

[0022] In the battery pack according to the eighth embodiment of the present invention, the battery cells are non-aqueous electrolyte secondary batteries. Furthermore, in the battery pack according to the eighth embodiment of the present invention, the battery cells are lithium ion batteries.

[0023] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper", "lower", and other terms including these terms) are used as necessary, but the use of these terms is for the purpose of facilitating understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. In addition, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members.

[0024] Furthermore, the embodiments shown below are specific examples of the technical ideas of the present invention, and do not limit the present invention to the following. Furthermore, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present invention, unless otherwise specified. Furthermore, the contents described in one embodiment or example can be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0025] A battery pack according to one embodiment of the present invention is shown in Fig. 1 to Fig. 7. Fig. 1 shows a perspective view of the battery pack, Fig. 2 shows a vertical longitudinal sectional view of the battery pack, Fig. 3 shows a vertical transverse sectional view of the battery pack, Fig. 4 shows an exploded perspective view of the battery pack, Fig. 5 shows an exploded perspective view of a core pack of the battery pack, Fig. 6 shows an exploded perspective view of a battery block, and Fig. 7 shows an enlarged sectional view of a main part of Fig. 2.

[0026] The battery pack 100 shown in Figures 1 to 6 comprises a battery block 10 consisting of multiple battery cells 1 arranged in fixed positions in a battery holder 2, a heat-resistant cap 5 connected to an end of the battery block 10, a circuit board 4 arranged along a first surface 10A of the battery block 10 and connected to the battery block 10, and an exterior case 9 housing the battery block 10 with the heat-resistant cap 5 and circuit board 4 connected to it.

[0027] The battery pack 100 is used, for example, as a power source for a portable electrical device such as a vacuum cleaner. However, the present invention does not specify the electrical device for which the battery pack is intended, and the battery pack can also be used as a power source for other electrical devices, such as power tools and assisted bicycles. The battery pack can be structured to be detachably connected to the electrical device, or can be built into the electrical device in a non-detachable state.

[0028] (Battery cell 1) Battery cell 1 is a cylindrical battery with an exhaust valve on end face 1a that opens when the internal pressure exceeds a set pressure. A cylindrical battery contains electrodes and electrolyte in a cylindrical metal case. The metal case has a sealed structure with a sealing plate hermetically fixed to the opening of a cylindrical exterior can that closes the bottom. The exterior can is manufactured by pressing a metal plate into a cylindrical shape. The sealing plate is hermetically fixed by crimping to the periphery of the opening of the exterior can via an insulating packing.

[0029] Although not shown, the battery cell 1 is provided with a discharge valve on the sealing plate to prevent the internal pressure of the metal case from becoming abnormally high and causing damage. The battery cell 1 has an opening for the discharge valve on the sealing plate, which opens to discharge internal gases and the like. However, the battery cell 1 can also have a discharge valve and its opening on the bottom of the exterior can. The discharge valve opens when the internal pressure exceeds a set pressure, for example, 1.5 MPa, to prevent the metal case from being destroyed by the internal pressure rise. The discharge valve opens under abnormal conditions. Therefore, when the discharge valve is open, the temperature of the battery cell 1 is also very high. Therefore, the gas and electrolyte (ejected material) discharged from the open discharge valve are abnormally high. In particular, a battery pack in which the battery cell 1 is a non-aqueous electrolyte secondary battery such as a lithium ion battery will discharge gas at an abnormally high temperature of 400°C or higher. Furthermore, since the lithium ion battery is filled with a non-aqueous electrolyte, if this is discharged to the outside of the case at a high temperature, it may come into contact with air and ignite, causing the temperature to become even higher. Not only in lithium-ion batteries, but also in other rechargeable batteries, the exhaust gas ejected from the open exhaust valve becomes very hot, so it is important to attenuate the energy of the exhaust gas and exhaust it outside the case to increase safety.

[0030] (Battery block 10) As shown in FIG. 6, a battery block 10 has multiple battery cells 1 arranged in parallel via a plastic battery holder 2. The battery block 10 in the figure has four battery cells 1 arranged in two rows and two columns in the battery holder 2. The battery block 10 in the figure has four battery cells 1 arranged in two rows and two columns, with each battery cell 1 connected in series with a lead plate 3. The battery block 10 in the figure has four battery cells 1 arranged in two rows and two columns and connected in series, but the number of battery cells 1 and the connection form can be freely changed. Each battery block 10 can be made common by arranging battery cells 1 of the same external shape, for example cylindrical batteries of the same dimensions, in fixed positions in battery holders 2 of the same shape and connecting the battery cells 1 with lead plates 3 of the same shape. Battery blocks 10 in which all parts are common can be mass-produced particularly cheaply.

[0031] (Battery holder 2) The battery holder 2 in Figures 5 and 6 arranges multiple battery cells 1 in a parallel position with the terminal surfaces at both ends on the same plane. The battery holder 2 arranges multiple battery cells 1 in multiple rows and columns. The battery holder 2 in the figures is made by molding plastic into a shape with a retaining cylinder 22 that holds four battery cells 1 in fixed positions. This battery holder 2 is shaped so that four sets of retaining cylinders 22 are connected in two rows and two columns in a parallel position, and the inside of the retaining cylinders 22 is made to be roughly the same shape as the outer shape of the battery cells 1 to form the retaining section 21.

[0032] In the battery block 10 of FIG. 6, the battery holder 2 is divided in the longitudinal direction of the battery cell 1 into a first battery holder 2A and a second battery holder 2B. The long and thin battery cell 1 can be smoothly inserted into this battery holder 2. The first battery holder 2A and the second battery holder 2B are separately manufactured by molding plastic, and are connected to each other by inserting the battery cell 1. The first battery holder 2A and the second battery holder 2B are provided with a cylindrical holding cylinder 22 so that the cylindrical battery cell 1 can be inserted and positioned in a fixed position. The inner shape of the holding cylinder 22 is almost the same as the outer shape of the battery cell 1, and more precisely, it is slightly larger so that the battery cell 1 can be smoothly inserted and positioned in a fixed position. The first battery holder 2A and the second battery holder 2B of this structure are connected to each other in a fixed position via the battery cell 1 with both ends of the cylindrical battery cell 1 inserted. The first battery holder 2A and second battery holder 2B can be connected more accurately by fitting their opposing surfaces together, and are connected in fixed positions via a non-melting plate (described below). The first battery holder 2A and second battery holder 2B, which are connected via the battery cell 1, are connected to a circuit board 4 and maintained in a connected state.

[0033] The battery block 10 shown in Figures 3 and 6 has retaining tubes 22 arranged between adjacent battery cells 1 as partition walls 23, and a non-molten plate 13, such as a mica plate, arranged inside the partition walls 23. The battery holder 2 shown in the figures arranges the battery cells 1 in two rows and two columns, so a cross-shaped partition wall 23 is provided between four sets of battery cells 1 arranged vertically and horizontally. The partition wall 23 has insertion gaps 25 into which the internal non-molten plate 13 is inserted. The partition wall 23 inserts the non-molten plate 13, such as a mica plate, into this insertion gap 25. This battery block 10 can prevent thermal runaway from being induced in an adjacent battery cell 1 when one of the battery cells 1 experiences thermal runaway and generates abnormal heat.

[0034] (Lead plate 3) The battery cells 1 in the battery block 10 are electrically connected in series via lead plates 3. The lead plates 3 are made by bending a metal plate with excellent conductivity. The lead plates 3 are fixed by welding to electrodes provided on the end faces of the battery cells 1. In the battery block 10 shown in FIG. 6, the individual battery cells 1 are connected in series via the lead plates 3 to increase the output voltage, but the battery block 10 can also connect the battery cells 1 in parallel via the lead plates 3, or in series and parallel. The lead plates 3 to which the battery cells 1 are connected are connected to a circuit board 4.

[0035] (Heat-resistant cap 5) In the battery pack 100 shown in Figs. 2 to 5, a heat-resistant cap 5 is connected to an end of the battery block 10 in order to attenuate and exhaust the energy of exhaust gas ejected from the exhaust valve of the battery cell 1 arranged at the first end 10a of the battery block 10. The heat-resistant cap 5 is produced by molding a thermoplastic plastic with better heat resistance than the battery holder 2 and the exterior case 9. Plastic with excellent heat resistance is produced by molding a fiber-reinforced plastic such as PBT resin reinforced with inorganic fibers such as glass fiber. The heat-resistant cap 5 is connected to the end of the battery block 10 to attenuate the energy of exhaust gas ejected from the valve-side end face of the battery cell 1 and change the flow direction. The heat-resistant cap 5 includes a closing plate portion 5X arranged opposite the end face 10X of the battery block 10 and a peripheral wall portion 5A connected to the periphery of the closing plate portion 5X, and the closing plate portion 5X and the peripheral wall portion 5A are molded into an integral structure.

[0036] A first discharge gap 11A is provided between the closing plate portion 5X and the end face 10X of the battery block 10 to discharge the exhaust gas ejected from the exhaust valve. In the first discharge gap 11A, the closing plate portion 5X causes the exhaust gas ejected from the exhaust valve to collide with its inner surface, thereby attenuating its energy. The first discharge gap 11A provided between the closing plate portion 5X and the end face 10X of the battery block 10, more precisely, between the closing plate portion 5X and the end face 1a of the battery cell 1, is set to, for example, 0.5 mm or more and 3 mm or less so that the exhaust gas can be smoothly discharged while attenuating the kinetic energy of the exhaust gas. A lead plate 3 fixed to the battery cell 1 is placed in the first discharge gap 11A.

[0037] The momentum of the exhaust gas passing through the first discharge gap 11A is weakened by the closing plate portion 5X and collides with the inside of the peripheral wall portion 5A. The peripheral wall portion 5A has a second discharge gap 11B between itself and the first surface 10A (the upper surface in the figure) of the battery block 10 in order to change the direction of the exhaust gas flowing in from the first discharge gap 11A and discharge it. The peripheral wall portion 5A causes the exhaust gas flowing in from the first discharge gap 11A to collide with the inside to attenuate its energy, and then changes the flow direction at a right angle to the longitudinal direction of the battery cell 1 without scattering it to the surroundings. The exhaust gas collides with the inner surface of the peripheral wall portion 5A, changes direction, attenuates its kinetic energy, and is discharged in the longitudinal direction of the battery cell 1.

[0038] The peripheral wall portion 5A has a second discharge gap 11B between it and the first surface 10A to allow the exhaust gas to flow between it and the battery block 10. The peripheral wall portion 5A shown in FIG. 3 and FIG. 7 is disposed away from the first surface 10A on which the circuit board 4 is disposed, and a second discharge gap 11B for guiding the exhaust gas is formed between the peripheral wall portion 5A and the first surface 10A. The exhaust gas that collides with the inside of the blocking plate portion 5X and flows into the second discharge gap 11B flows into the ventilation gap 12 formed between the circuit board 4 and the battery block 10. The heat-resistant cap 5 shown in the figure is disposed in a stacked state with the tip of the peripheral wall portion 5A on the edge portion of the circuit board 4 so that the exhaust gas that passes through the second discharge gap 11B smoothly flows into the ventilation gap 12 formed between the circuit board 4 and the battery block 10. 7 is disposed so that the tip of the peripheral wall portion 5A is inserted between the first surface 10A of the battery block 10 and the circuit board 4 in a plan view, so that the second discharge gap 11B communicates with the ventilation gap 12. The peripheral wall portion 5A is preferably laminated on the circuit board 4 in contact therewith. However, the peripheral wall portion can also be laminated on the circuit board in a non-contact state. The peripheral wall portion can also be laminated on the upper surface of the circuit board.

[0039] 3 and 5 includes sub-circumferential wall portions 5B and 5C that are connected to the periphery of the closing plate portion 5X and connected to the outer peripheral surface of the battery block 10. The heat-resistant cap shown in the figures includes a sub-circumferential wall portion 5B that is connected to the second surface 10B (both side surfaces in the figures) adjacent to the first surface 10A, which is the outer peripheral surface of the battery block 10, and a sub-circumferential wall portion 5C that is connected to a third surface 10C (bottom surface in the figures) that faces the first surface 10A. As shown in FIG. 3, the heat-resistant cap 5 connects the sub-circumferential wall portion 5B to the outside of the second surface 10B of the battery block 10, and connects the sub-circumferential wall portion 5C to the outside (lower surface) of the third surface 10C of the battery block 10. That is, the heat-resistant cap 5 is connected to a fixed position at the end of the battery block 10 with the sub-circumferential wall portions 5B and 5C in close contact with the outer peripheral surface of the battery block 10. In this way, the heat-resistant cap 5 having the sub-circumferential wall portions 5B, C that contact and are connected to the outer peripheral surface of the battery block 10 prevents exhaust gas injected into the first discharge gap 11A from leaking to both sides and below the battery block 10, and can reliably guide the exhaust gas discharged into the first discharge gap 11A to the second discharge gap 11B. However, the heat-resistant cap 5 does not necessarily need to have both the sub-circumferential wall portion 5B that is connected to the side surface of the battery block 10 and the sub-circumferential wall portion 5C that is connected to the bottom surface, and only one of them may be provided.

[0040] Furthermore, the heat-resistant cap 5 shown in Figs. 5 and 7 is provided with a partition wall 5M that is disposed between the end faces 1a of the adjacent battery cells 1 and divides the first discharge gap 11A between the end faces 1a of the respective battery cells 1. The partition wall 5M is fixed vertically to the inner surface of the closing plate portion 5X and divides the first discharge gap 11A between the end faces 1a of the battery cells 1. The partition wall 5M divides the gap between the valve-side end face of the abnormal battery cell whose discharge valve is open and the closing plate portion 5X, and the gap between the adjacent battery cell and the closing plate portion 5X. When the battery cell 1 experiences thermal runaway due to, for example, an internal short circuit, the internal pressure rises abnormally and the discharge valve opens. In this state, the exhaust gas ejected from the discharge valve becomes abnormally hot. When the high-temperature exhaust gas heats the adjacent battery cells, it causes thermal runaway to occur. The partition wall 5M prevents the high-temperature exhaust gas from flowing to the end faces of the adjacent battery cells, thereby preventing the induction of thermal runaway. The partition wall 5M is provided to prevent exhaust gas emitted from an abnormal battery cell from heating adjacent battery cells 1, and defines a first exhaust gap 11A between the battery cells 1.

[0041] The partition wall 5M prevents the ejected exhaust gas from flowing to the end face 1a of the adjacent battery cell 1, thereby preventing the exhaust gas from heating the adjacent battery cell 1. The partition wall 5M protrudes from the closing plate portion 5X into the first exhaust gap 11A and is disposed between the end faces 1a of each battery cell 1. The partition wall 5M disposed in the first exhaust gap 11A protrudes from the inner surface of the closing plate portion 5X and comes into contact with the surface of the lead plate 3, dividing the first exhaust gap 11A between the battery cells 1.

[0042] (Circuit board 4) The circuit board 4 is equipped with a protection circuit that charges and discharges the battery cells 1, and connects each battery cell 1 to the protection circuit. The protection circuit detects the voltage and current of each battery cell 1 and controls the charging and discharging current to charge and discharge while protecting the battery. The circuit board 4 can also connect output lead parts 3x for inputting the positive and negative outputs of each battery block 10, or intermediate potential lead parts 3y for measuring an intermediate potential in order to grasp the voltage of each battery cell 1, or the potential of a temperature detection part (not shown) for detecting the temperature of each battery cell 1. A thermistor or the like is used as the temperature detection part.

[0043] The circuit board 4 is disposed along the first surface 10A (upper surface in the figure) of the battery block 10 adjacent to the end surface 10X on which the heat-resistant cap 5 is disposed. The circuit board 4 is disposed in a state in which a ventilation gap 12 is formed between the circuit board 4 and the first surface 10A of the battery block 10. This ventilation gap 12 is a gap that allows exhaust gas that is discharged from the exhaust valve of the battery cell 1 and has passed through the first exhaust gap 11A and the second exhaust gap 11B to pass through. As the high-temperature exhaust gas passes through this ventilation gap 12, it comes into contact with the battery holder 2 and members provided on the circuit board 4, and the kinetic energy and thermal energy are attenuated. The circuit board 4 is fixed to the battery block 10 so that the distance of the ventilation gap 12 is, for example, 2.5 mm to 3.0 mm.

[0044] The circuit board 4 is connected to a fixed position on the first surface 10A of the battery block 10, and the ventilation gap 12 is formed to have a specified distance. The battery holder 2 shown in the perspective view of FIG. 6 has mating protrusions 29 protruding from the surface facing the circuit board 4 (the upper surface in the figure) in order to connect the circuit board 4 to a fixed position. The mating protrusions 29 are hollow columnar bosses that protrude vertically upward from the four corners of the facing surface, and are formed by molding integrally with the plastic of the battery holder 2. As shown in FIG. 4, the mating protrusions 29 guide the mating recesses 4a formed in the circuit board 4 to position the circuit board 4 in a fixed position. Furthermore, the battery holder 2 shown in FIG. 6 has mounting ribs 31 molded integrally at multiple locations on the facing surface for placing the circuit board 4 thereon to determine its up-down position. The mounting ribs 31 are provided at multiple locations on both sides of the opposing surface of the battery holder 2, and position the circuit board 4 at a fixed position with a specified distance from the first surface 10A. Furthermore, the battery block 10 in FIG. 6 is provided with a locking hook 30 for the circuit board 4 that is integrally molded on the opposing surface of the battery holder 2. As shown in FIG. 4, the locking hook 30 locks the circuit board 4 placed on the first surface 10A and positions it in a fixed position. The output lead portion 3x and the intermediate potential lead portion 3y that protrude from the first surface 10A of the battery block 10 are inserted into the through holes of the circuit board 4, the mating convex portion 29 of the battery holder 2 is guided into the mating concave portion 4a, and the bottom surface of the circuit board 4 is placed on the mounting ribs 31 and then engaged with the locking hook 30 to position it in the fixed position. With the circuit board 4 set in place by the locking hooks 30, the output lead 3x and the intermediate potential lead 3y are soldered to the connections of the circuit board 4, and the battery block 10 is connected.

[0045] Furthermore, the circuit board 4 shown in the figure connects multiple battery blocks 10, electrically connecting and further physically connecting each battery block 10. The battery pack 100 shown in the exploded oblique view of Figure 5 connects the multiple battery blocks 10 even more firmly by screwing the circuit board 4 to two sets of battery blocks 10 with set screws 18 that penetrate the circuit board 4. The battery block 10 has fixing bosses 28, into which the set screws 18 are screwed, on the surface facing the battery holder 2.

[0046] The output lead portions 3x of the battery blocks 10 are connected via a circuit board 4, and further connected to a connector 19. The circuit board 4 has a conductive layer (not shown) such as copper foil on its surface. The conductive layer electrically connects the connection portions of the output lead portions 3x to connect the battery blocks 10 in series, and also connects the output lead portions 3x to lead wires 16 of the connector 19. The conductive layer also connects the connection portion of the intermediate potential lead portion 3y to a protection circuit of the circuit board 4.

[0047] As described above, the battery core pack 20 is formed by fixing the battery blocks 10 to the circuit board 4 while being connected in a straight line. The core pack 20 shown in the figure has two battery blocks 10 connected in a straight line, with an insulating plate section 6 disposed between the opposing battery blocks 10 to insulate them from each other, heat-resistant caps 5 connected to both ends, and a circuit board 4 connected to the first surface 10A of the battery block 10. The insulating plate section 6 is disposed between the battery blocks 10 arranged in the longitudinal direction. The insulating plate section 6 is produced by molding a material with excellent insulating and heat-insulating properties, such as PBT resin, which is a fiber-reinforced plastic reinforced by embedding inorganic fibers such as glass fibers. However, an inorganic plate such as a mica plate can also be used for the insulating plate section.

[0048] (Outer case 9) The exterior case 9 is formed in a rectangular cylindrical box shape as shown in Figs. 1 to 4. The exterior case 9 in the figures is divided into a case main body 9A and a closing portion 9B. As shown in Fig. 3, the exterior case 9 houses a battery core pack 20 including two battery blocks 10, heat-resistant caps 5 disposed at the ends of the battery blocks 10, and a circuit board 4 connected to the battery blocks 10. The exterior case 9 extends a connector 19 to the outside for connection to an electrical device to which power is supplied by the battery pack 100. The exterior case 9 is made of a material with excellent insulating and heat-insulating properties, such as polycarbonate or ABS, or a resin that combines these.

[0049] The above-mentioned exterior case 9 has an exhaust section 15 that exhausts the exhaust gas discharged from the exhaust valve to the outside. In the exterior case 9 shown in the figure, the exhaust section 15 is an end of the case body 9A, where the connector 19 is drawn out of the case. This exterior case 9 has a structure in which an opening window 9a is provided in the case body 9, and the lead wire 16 is guided into a groove 9b provided in the opening edge of the opening window 9a to draw the connector 19 out of the case. Therefore, in this exterior case, the opening window 9a and the groove 9b through which the lead wire is drawn out serve as an exhaust section for exhausting the exhaust gas in the case to the outside. In this exterior case 9, the connector 19 is passed through the opening window 9a opened in the case body 9A, the battery core pack 20 is stored in the case body 9A, and then the case body 9A is closed with the lid 9B, the lead wire 16 is passed through the groove 9b provided in the peripheral portion of the opening window 9a, and then the opening window 9a of the case body 9A is closed with the closing lid 17.

[0050] Furthermore, the exterior case 9 shown in Fig. 2 has a surface plate portion 9x in which the case body 9A faces the circuit board 4. When the exterior case 9 houses the battery core pack 20 inside, an expansion gap 14 for exhaust gas is formed between the circuit board 4 and the surface plate portion 9x. In this battery pack 100, the exhaust gas that has passed through the ventilation gap 12 passes through the expansion gap 14 and is exhausted to the outside from the exhaust section 15. In this way, according to the structure in which the exhaust gas that has passed through the ventilation gap 12 passes through the expansion gap 14 and is exhausted to the outside from the exhaust section 15, the exhaust gas whose energy has been attenuated in the ventilation gap 12 can be further attenuated in the expansion gap 14 and exhausted to the outside.

[0051] Furthermore, the exterior case 9 shown in FIG. 2 has an exhaust section 15 on the surface plate section 9x at the end opposite the first end section 10a of the battery block 10. The battery pack 100 having the above structure has the exhaust section 15 on the surface plate section 9x at the end of the exterior case 9 opposite the first end section 10a of the battery block 10, and yet can reliably attenuate the energy of the exhaust gas discharged from the exhaust section 15. This structure reliably attenuates and discharges the energy of the exhaust gas by diverting it to the ventilation gap 12 while arranging the first end section 10a of the battery block 10, where the exhaust valve of the battery cell 1 is arranged, close to the exhaust section 15 provided on the surface plate section 9x. Therefore, despite the linear distance between the exhaust valve of the battery cell 1 and the exhaust section 15 of the exterior case 9 being shortened, the path of the exhaust gas can be lengthened, and the energy can be reliably attenuated.

[0052] In the exterior case shown in FIG. 3, the exhaust section 15 is provided at the end of the surface plate section of the case body 9A, which is on the same side as the first end section 10a provided on the battery block 10, but the exhaust section 15 may be provided in the center or on the side of the surface plate section 9x of the case body 9A. Even in this case, exhaust gas discharged from the exhaust valve side end face 1a of the battery cell 1 arranged at the first end section 10a of the battery block 10 passes through the exhaust gap 11 consisting of the first exhaust gap 11A and the second exhaust gap 11B to the ventilation gap 12, and also passes through the ventilation gap 12 to the expansion gap 14, before being discharged to the outside from the exhaust section 15. In this way, the battery pack of the present invention allows high-temperature exhaust gas to pass through the ventilation gap 12 formed between the battery block 10 and the circuit board 4, thereby lengthening the path of the exhaust gas and reliably attenuating its energy before discharging it to the outside. Furthermore, the battery pack 100 can lengthen the path of exhaust gas even at the exhaust valve side end faces of battery cells arranged in positions other than the first end 10a of the battery block 10, allowing the gas to be exhausted to the outside while attenuating its energy.

[0053] (Heat dissipation plate 8) Furthermore, the battery pack 100 in Fig. 4 has a heat dissipation plate 8 disposed on the underside of the core pack 20 to more effectively attenuate the energy of exhaust gas. The heat dissipation plate 8 is disposed inside the closing portion 9B of the exterior case 9 and between it and the battery block 10, and attenuates the energy of exhaust gas emitted from the battery cells 1. A plate material with better thermal conductivity than the exterior case 9 is suitable for the heat dissipation plate 8. This heat dissipation plate 8 absorbs the thermal energy of the exhaust gas that it collides with, and quickly diffuses the absorbed thermal energy over a wide area for thermal conduction to the exterior case 9, which then dissipates the thermal energy to the outside over a wide area.

[0054] A metal plate is used for the heat dissipation plate 8 as a plate material with favorable heat conduction properties. In particular, an aluminum (including aluminum alloy) plate is suitable for the heat dissipation plate 8. An aluminum plate has heat resistance, excellent heat conduction properties, and is lightweight, so it can quickly diffuse the thermal energy of the exhaust gas and dissipate heat efficiently while reducing weight. The battery pack 100 in FIG. 4 has a strip shape arranged along the longitudinal direction of the blocking portion 9B, and is bent at both ends into an L-shape and arranged between the heat-resistant cap 5 and the exterior case 9. This covers the case connection parts at both ends of the exterior case 9 from the inside, preventing the exhaust gas discharged from the exhaust valve from being discharged to the outside from these parts. [Industrial Applicability]

[0055] The battery pack of the present invention is suitably used as a power source for portable electrical devices such as vacuum cleaners, power tools, and power-assisted bicycles. [Explanation of symbols]

[0056] 100…Battery pack 1. Battery cell 1a...end face 2…Battery holder 2A…1st battery holder 2B…Second battery holder 3...Lead plate 3x…Output lead 3y...Intermediate potential lead 4…Circuit board 4a…Mating recess 5…Heat-resistant cap 5X…Closing plate section 5A…Peripheral wall part 5B...Second peripheral wall portion 5C…Third peripheral wall 5M…Bulkhead 6…Insulating plate part 8…Heat dissipation plate 9…Outer case 9A…Case body 9a…Opening window 9b…Groove 9x…Surface plate section 9B…Occluded part 10…Battery block 10a...First end 10X...end face 10A…First surface 10B...Second surface 10C…Third Surface 11...Discharge gap 11A…First discharge gap 11B…Second discharge gap 1 2…Ventilation gap 13…Non-melting plate 14...Expansion gap 15…Exhaust section 16…Lead wire 17…occlusion lid 18…Set screw 19…Connector 20…Core Pack 21...Holding part 22...Holding tube 23…Partition wall 25…Insertion gap 28...Fixed boss 29…Fitting protrusion 30…Latching hook 31...Ribs

Claims

1. a battery block including a plurality of battery cells arranged in fixed positions in a battery holder, the battery cells having exhaust valves that open when the internal pressure exceeds a set pressure; a heat-resistant cap connected to an end of the battery block; a circuit board disposed along a first surface adjacent to the end face of the battery block on which the heat-resistant cap is disposed and connected to the battery block; an exterior case that houses the battery block to which the heat-resistant cap and the circuit board are connected, the exterior case having an exhaust section that exhausts exhaust gas discharged from the exhaust valve to the outside; A battery pack comprising: The battery block includes: a discharge valve side end surface on which a discharge valve for the battery cell is provided is disposed at a first end formed by connecting the heat-resistant caps; The heat-resistant cap is a closing plate portion that defines a first discharge gap between itself and an end face of the battery block; a peripheral wall portion connected to a periphery of the closing plate portion and defining a second discharge gap between the peripheral wall portion and a first surface of the battery block, The circuit board includes: a ventilation gap is formed between the first surface of the battery block and the battery block, and an edge portion of the first end side is laminated to the peripheral wall portion, and the ventilation gap is communicated with the second exhaust gap; A battery pack characterized in that exhaust gas discharged from the exhaust valve of the battery cell passes through an exhaust gap consisting of the first exhaust gap and the second exhaust gap, passes through the ventilation gap, and is exhausted to the outside from the exhaust section.

2. 2. The battery pack according to claim 1, an outer circumferential surface of the battery block has a second surface adjacent to the first surface and a third surface facing the first surface; a sub-circumferential wall portion connected to the periphery of the closing plate portion and connected to at least one of the second surface and the third surface of the outer circumferential surface of the battery block,

3. 3. The battery pack according to claim 1, the heat-resistant cap is disposed between end faces of adjacent battery cells and includes a partition wall that defines the first discharge gap at each end face of the battery cells.

4. 4. The battery pack according to claim 1, the exterior case includes a surface plate portion facing the circuit board, and an expansion gap for exhaust gas is formed between the surface plate portion and the circuit board, The battery pack is characterized in that the exhaust gas that has passed through the ventilation gap is passed through the expansion gap and is exhausted to the outside from the exhaust portion.

5. 5. The battery pack according to claim 4, a first end of the battery block and a second end of the battery block that are spaced apart from each other, the first end being opposite to the first end of the battery block and the second end being opposite to the first end of the battery block;

6. 6. The battery pack according to claim 1, The battery pack according to claim 1, wherein the heat-resistant cap is made of a reinforced plastic material having an inorganic material embedded in the resin for reinforcement.

7. 7. The battery pack according to claim 1, a battery pack comprising: said battery cells being cylindrical batteries; and a plurality of cylindrical batteries being arranged with their end faces flush with one another and in a parallel position in said battery holder to form a battery block.

8. 8. The battery pack according to claim 7, The battery pack, wherein the battery cells are lithium ion batteries.

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