Battery pack

Abstract

Provided is a battery pack in which damage to a lead plate can be reduced when high-temperature and high-pressure gas is discharged from a secondary battery cell. A battery pack (100) is provided with: a plurality of secondary battery cells (1) in which an outer can (1b) has a cylindrical shape and in which one or more gas discharge ports (1a) are provided in a circular end surface (1c); an exterior case (10) that houses the plurality of secondary battery cells (1); and one or more lead plates (30) connected to an end surface (1c) of any one of the plurality of secondary battery cells (1). In addition, the present invention is provided with a path-defining unit (25) that defines a gas discharge path (40) disposed so as to face at least one of the one or more gas discharge ports (1a). The path-defining unit (25) defines a first path (41) along a first direction from the center direction of the circular shape of the end surface (1c) of the outer can (1b) toward the circumferential direction, and a second path (42) along a second direction from the circumferential direction of the circular shape of the end surface (1c) of the outer can (1b) toward the center direction.

Description

Technical Field

[0001] The present disclosure relates to battery packs. Background Art

[0002] In order to drive electrical equipment using rechargeable secondary batteries such as lithium-ion secondary batteries, a battery pack is used in which a plurality of secondary battery cells are housed in an outer casing (e.g., Patent Document 1). For example, a battery pack in which a plurality of secondary battery cells using cylindrical outer cans are connected in series or in parallel to achieve high output and high capacity is described in detail in the following examples. Fig. 9 As shown in the stereoscopic view, the end faces of the cylindrical outer cans are aligned to the same plane, and then welded through a flat lead plate 930 so as to cover the end faces of the outer cans of each secondary battery cell. In addition, the battery pack is provided with a fuse to protect the battery pack from unintended large currents. For example, Fig. 9 In the example of the lead plate 930 shown, a narrow area is provided in a part of the lead plate 930 to locally increase the resistance value, thereby providing a fuse structure 938 so that it melts and is cut off due to Joule heat when a large current is passed.

[0003] In such a battery pack, each secondary battery cell has a gas outlet disposed on the outer can, and the outlet is used to discharge high-temperature and high-pressure gas from the outer can in the event of some abnormality that causes the interior of the outer can to become high-pressure. For example, in a secondary battery cell using a cylindrical outer can, a gas outlet is opened on the end face of the cylindrical outer can. In a battery pack using such secondary battery cells, when high-temperature and high-pressure gas is ejected from the gas outlet of a secondary battery cell, it is desired to quickly discharge the gas from the inside of the outer shell to the outside.

[0004] However, in Fig. 9 In a battery pack 900 in which the end faces of adjacent secondary battery cells are connected to each other by a lead plate 930 as shown in the perspective view of Fig.10 As shown in the cross-sectional view of FIG. 1 , welding is performed with the end faces of each secondary battery cell 901 covered by the lead plate 930. In this state, the gas outlet opening at the end face of the outer can is covered by the lead plate 930. In this state, Fig.11As shown, if high-temperature and high-pressure gas is discharged from the gas outlet 901a of a secondary battery cell 901, the lead plate is heated due to the high temperature and further exposed to the high-pressure gas, which may cause damage. It is believed that in this case, if the lead plate breaks and its resistance value increases, the current value decreases, and as a result, the fuse structure 938 no longer operates. If the fuse structure 938 does not operate, the power supply to other secondary battery cells cannot be stopped, and the secondary battery cells are abnormally heated due to the Joule heat generated by the power supply, resulting in the worry of increasing abnormal secondary battery cells.

[0005] In addition, through experiments conducted by the inventors of the present application, it was found that the following situation may occur: the high-temperature and high-pressure gas discharged from the secondary battery cell 901A hits the back side of the lead plate 930 and rebounds, and is irradiated to the end face of the adjacent secondary battery cell 901B. In this state, the end face of the normal secondary battery cell 901B is exposed to the high-temperature and high-pressure gas, resulting in an abnormal state, and sometimes there is a concern that the abnormal secondary battery cell will spread.

[0006] Prior Art Literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-174673 Summary of the invention

[0009] Problems to be solved by the invention

[0010] One of the objects of the present disclosure is to provide a battery pack capable of reducing damage to a lead plate and adverse effects on adjacent secondary battery cells when high-temperature and high-pressure gas is discharged from a secondary battery cell.

[0011] Means for solving problems

[0012] A battery pack according to one embodiment of the present invention comprises: a plurality of secondary battery cells, an outer can is set to be cylindrical, and one or more gas exhaust ports are provided on the circular end face of the outer can; an outer shell body accommodating the plurality of secondary battery cells; and one or more lead plates connected to the end face of any one of the plurality of secondary battery cells, the battery pack comprising: a path defining portion defining a gas exhaust path arranged facing at least any one of the one or more gas exhaust ports, the path defining portion defining a first path and a second path, the first path being along a first direction from the center direction of the circular end face of the outer can toward the circumferential direction, and the second path being along a second direction from the circumferential direction of the circular end face of the outer can toward the center direction.

[0013] Effects of the Invention

[0014] According to a battery pack involved in one aspect of the present invention, even if high-temperature and high-pressure gas is discharged from the gas outlet of any secondary battery cell, it is possible to avoid the high-temperature and high-pressure gas from being directly discharged to the lead plate to improve safety. That is, the gas is guided to a gas discharge path arranged facing at least any one of the gas discharge ports, and a first path along a first direction from the center direction of the circular shape of the end face of the outer can toward the circumferential direction and a second path along a second direction from the circumferential direction toward the center direction are provided in the gas discharge path to increase pressure loss, thereby causing the gas pressure to drop and then flow to the lead plate side, thereby preventing the lead plate from being damaged and preventing the gas rebounded by the lead plate connecting the end faces of adjacent secondary battery cells from propagating to the end faces of adjacent secondary battery cells and heating them. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a perspective view showing a battery pack according to Embodiment 1 of the present invention.

[0016] Figure 2 yes Figure 1 An exploded perspective view of a battery pack.

[0017] Figure 3 It is shown Figure 2 A three-dimensional view of a battery module.

[0018] Figure 4 Observed from the back Figure 3 A three-dimensional view of a battery module.

[0019] Figure 5 is from Figure 3 An exploded perspective view of a battery module with the lead plate removed.

[0020] Figure 6 is from Figure 4 An exploded perspective view of a battery module with the lead plate removed.

[0021] Figure 7 is from Figure 5 An exploded perspective view of the battery holder is further removed.

[0022] Figure 8 yes Figure 3 Cross-sectional view of the battery module taken along line VIII-VIII.

[0023] Fig. 9 It is a perspective view showing a battery pack according to a comparative example.

[0024] Fig.10 It is shown Fig. 9 A schematic cross-sectional view of a portion of a gas outlet of a battery pack.

[0025] Fig.11 It is shown in Fig. 9 A schematic cross-sectional view of a state in which gas is exhausted from one secondary battery cell in a battery pack and is reflected by a lead plate.

[0026] Fig.12 is from Figure 7 Stereoscopic image observed along line XII-XII.

[0027] Fig.13 It is shown in Fig.12 An enlarged stereoscopic view of the state of being cut at the XIII-XIII line.

[0028] Fig.14 is Figure 5 FIG. 1 is a perspective view of a path defining portion of a battery module.

[0029] Fig.15 It is shown Figure 3 An enlarged perspective front view of the lead plate welding portion of a battery module.

[0030] Fig.16 is from Fig.15 Front perspective view with lead plate removed.

[0031] Fig.17 Observed from the back side Fig.16 Figure 1. A diagram of a battery holder.

[0032] Fig.18 yes Fig.16 An enlarged perspective front view of the portion surrounded by circle XVIII at the lower left.

[0033] Fig.19 yes Fig.16 An enlarged perspective front view of the portion surrounded by circle XIX on the upper right.

[0034] Fig. 20 It is shown Fig.17 An enlarged view of a portion of a path defining portion of a battery holder.

[0035] Fig.21 It is shown Fig. 20 A graph showing the pressure of gas at various locations.

[0036] Fig. 22 It is shown Fig. 20 A graph showing the flow rate of gas at various positions.

[0037] Fig.23 This is a schematic diagram showing a path defining portion of a battery pack according to the second embodiment.

[0038] Fig.24 This is a schematic diagram showing a path defining portion of a battery pack according to the third embodiment.

[0039] Fig.25 This is a schematic diagram showing a path defining portion of a battery pack according to a fourth embodiment.

[0040] Fig.26 This is a schematic diagram showing a path defining portion of a battery pack according to a fifth embodiment.

[0041] Fig. 27 This is a schematic diagram showing a path defining portion of a battery pack according to a sixth embodiment. DETAILED DESCRIPTION

[0042] The aspects of the present invention can also be identified by the following structures and features.

[0043] Regarding a battery pack according to another embodiment of the present invention, in the above embodiment, the lead plate has a fuse structure that breaks when a current exceeding a given value flows. With the above structure, in the event that high-temperature and high-pressure gas is discharged from a secondary battery cell, it is possible to avoid the high-temperature and high-pressure gas being directly irradiated to the lead plate having the fuse structure, thereby preventing the fuse structure from being properly operated, thereby improving reliability.

[0044] In addition, a battery pack according to another aspect of the present invention, in any of the above aspects, further comprises a battery holder for holding the plurality of secondary battery cells, wherein the path defining portion is formed on an inner surface of the battery holder facing end surfaces of the secondary battery cells.

[0045] Further, regarding a battery pack according to another embodiment of the present invention, in any of the above embodiments, the path defining portion includes one or more baffles extending between the central direction and the circumferential direction of the circular shape of the end face of the outer can, the first path is provided on one side of the one or more baffles along the extending direction, and the second path is provided on the other side, and a first guide port communicating with the first path and a second guide port communicating with the second path are opened on both sides of a first end face of the one or more baffles facing the central side of the circular shape of the end face of the outer can, respectively, and the first path and the second path are communicated on the second end face of the one or more baffles facing the circumferential side of the circular shape of the end face of the outer can. With the above structure, high-temperature and high-pressure gas can be guided from both or either of the first guide port and the second guide port to the first path and / or the second path, the flow path of the gas discharge path can be lengthened, and the traveling direction is changed at the connection portion between the first path and the second path, thereby causing momentum loss and reducing the pressure of the gas. Furthermore, by guiding the gas from both the first guide port and the second guide port, high-pressure gases can collide with each other in the middle of the gas guide path to generate a vortex, thereby achieving a pressure reduction.

[0046] Furthermore, in another embodiment of the present invention, in any of the above embodiments, the first path is defined so that the opening width becomes narrower from the first guide port toward the second end face side, and the second path is defined so that the opening width becomes narrower from the second guide port toward the second end face side. With the above structure, the high-temperature and high-pressure gas guided from either the first guide port or the second guide port has a faster flow rate and a lower pressure due to the gradual reduction of the flow path area, and then expands when going to the second guide port or the first guide port due to the expansion of the flow path area, thereby becoming a reverse pressure gradient state in which the pressure rises instead, and as a result, the pressure loss can be increased to reduce the pressure of the gas.

[0047] Furthermore, in another embodiment of the present invention, the first guide port and the second guide port are defined by a curved surface. The above structure can reduce pressure loss in the first guide port and the second guide port, making it easier to guide gas to the gas discharge path.

[0048] Furthermore, in a battery pack according to another aspect of the present invention, in any of the above aspects, a plurality of baffles are provided.

[0049] Furthermore, in addition, regarding a battery pack involved in another embodiment of the present invention, in any of the above-mentioned embodiments, the multiple baffles are arranged to be separated by a first distance that is equally spaced from each other, and the one or more gas exhaust ports have multiple gas exhaust ports separated by a second distance that is equally spaced from each other and different from the first distance.

[0050] Furthermore, in addition, regarding the battery pack involved in another embodiment of the present invention, in any of the above embodiments, m, which is the number of the gas outlets, and n, which is the number of the baffles, are mutually prime. Through the above structure, regardless of the rotation direction of the secondary battery cell, the first guide port and the second guide port defined by the baffle and the gas outlet must be opposite to each other at any position, so that the high-temperature and high-pressure gas can be reliably guided to the first guide port and the second guide port. That is, there is no need to position the rotation direction of the secondary battery cell and the relative position of the baffle, which can obtain the advantage of simplifying the assembly process of the battery pack.

[0051] Furthermore, in another embodiment of the present invention, the baffles are arranged radially relative to the center of the circular shape of the end surface of the outer can in any of the above embodiments, the path defining portion is formed with a wall portion, the wall portion is separated from the radial baffles, and the wall portion is formed into a mountain shape along the outer edge of the baffle, and the gas exhaust path is formed into a U-shape between the wall portion and the baffle. With the above structure, by arranging the baffles radially, it is possible to cause pressure loss in the ejected gas, reduce the total pressure of the ejected gas irradiated to the lead plate, and reduce damage to the lead plate.

[0052] Furthermore, in a battery pack according to another aspect of the present invention, in any of the above aspects, an opening width between the second end surface of each baffle and the wall portion is formed narrower than the first guide opening and the second guide opening.

[0053] Hereinafter, the embodiments of the present invention will be described based on the accompanying drawings. However, the embodiments shown below are examples for concretizing the technical ideas of the present invention, and the present invention is not limited by the following contents. In addition, this specification will never limit the components shown in the claims to the components of the embodiments. In particular, as long as there is no special limiting record about the size, material, shape, relative configuration, etc. of the structural parts recorded in the embodiments, the main purpose is not to limit the scope of the present invention to only this, but is just an illustrative example. In addition, the size, positional relationship, etc. of the components shown in the drawings are sometimes exaggerated in order to make the description clear. Further, in the following description, for the same name, symbol, the same or homogeneous components are represented, and detailed description is appropriately omitted. Further, with respect to the various elements constituting the present invention, it can also be set to make multiple elements consist of the same components so that one component can share multiple elements, and it can also be realized by sharing the function of one component by multiple components on the contrary.

[0054] The battery pack of the present invention can be used as a driving power source for autonomous robots for delivery, electric carts for delivery, electric scooters for golf courses, construction machinery, hybrid vehicles, electric vehicles and other vehicles. In addition, in addition to the driving power source for power-assisted bicycles, it can also be used as a power source for portable electrical equipment such as wireless devices, electric cleaners, and electric tools. Or it can also be used as a backup power source for servers, or a power supply device for home use, production service sites, and factories for stationary power storage purposes. Below, as one embodiment of the present invention, a battery pack used as a driving power source for an autonomous robot is described.

[0055] [Implementation Method 1]

[0056] exist Figures 1 to 8 1 and 2 show a battery pack 100 according to Embodiment 1 of the present invention. In these figures, respectively, Figure 1 FIG. 1 is a perspective view showing a battery pack 100 according to Embodiment 1 of the present invention. Figure 2 Shows Figure 1 An exploded perspective view of the battery pack 100, Figure 3 Shows Shows Figure 2 A perspective view of a battery module 2, Figure 4 Shown from the back Figure 3 A perspective view of a battery module 2, Figure 5 Shows from Figure 3 An exploded perspective view of the battery module 2 with the lead plate 30 removed, Figure 6 Shows from Figure 4 An exploded perspective view of the battery module 2 with the lead plate 30 removed, Figure 7 Shows from Figure 5 Further removed the battery holder 20 of the exploded perspective view, Figure 8 Shows Figure 3 1 and 2 are cross-sectional views of a battery module 2 taken along line VIII-VIII. The battery pack 100 shown in these figures includes an outer casing 10 and a battery module 2. The battery module 2 includes one or more secondary battery cells 1.

[0057] (External casing 10)

[0058] The outer casing 10 accommodates a battery module 2 composed of one or more secondary battery cells 1 and a circuit board 3. Figure 1 , Figure 2 As shown in FIG. 1 and FIG. 2 , the outer casing 10 is formed into a box-shaped rectangular shape extending in one direction when viewed from above. The box-shaped outer casing 10 has a first surface and a second surface intersecting the first surface. Figure 1 In the example of FIG. 1 , the top surface is set as the first surface, and the side surface along the length direction is set as the second surface. Figure 2 As shown in FIGS. 1 and 1 , a storage space for storing the battery module 2 and the circuit board 3 is provided inside the outer casing 10 .

[0059] like Figure 2 As shown, the outer casing 10 is, for example, divided into two parts, an upper casing 11 and a lower casing 12. The divided upper casing 11 and the lower casing 12 are fixed by screwing, fitting, bonding, ultrasonic welding, etc. at their corners. In addition, the structure is not limited thereto, and for example, it may be divided into a bottomed cylindrical portion with one side open and a cover portion that blocks the open surface, or it may be decomposed into three or more parts.

[0060] (Battery module 2)

[0061] exist Figure 3 to Figure 7 2 and 3 show a battery module 2. As shown in these figures, the battery module 2 includes a plurality of secondary battery cells 1, a battery holder 20 for housing these secondary battery cells 1, and a lead plate 30.

[0062] (Battery holder 20)

[0063] The battery holder 20 is provided with a plurality of storage tubes 24 for individually storing the secondary battery cells 1. Figure 7 In the example shown, the cylindrical secondary battery cell 1 is divided into a first holder 21 and a second holder 22 in the longitudinal direction, and the secondary battery cell 1 is stored in the storage tube 24 from each end face 1c in the longitudinal direction. In addition, an opening 23 is formed on the end face of the storage tube 24 to expose the end face 1c of the secondary battery cell 1. Such a battery holder 20 can be made of a resin such as polycarbonate with excellent insulation.

[0064] In addition, if Figure 2As shown in the exploded perspective view of FIG. 1 , the circuit substrate 3 is placed on the upper surface of the battery holder 20. The battery holder 20 holds the secondary battery cell 1 and the circuit substrate 3. The battery module 2 is connected to the circuit substrate 3 via the lead plate 30. A placement surface for placing the circuit substrate 3 is formed on the upper surface of the battery holder 20 constituting the battery module 2.

[0065] (Circuit board 3)

[0066] The battery module 2 is connected to the circuit board 3 via the lead plate 30. The circuit board 3 is mounted with a charge and discharge circuit for charging and discharging the secondary battery cells 1, a protection circuit for monitoring the voltage and temperature of the secondary battery cells 1 and cutting off the current in the event of an abnormality, etc. The circuit board 3 is made of a glass epoxy substrate, etc.

[0067] (Secondary battery cell 1)

[0068] One or more secondary battery cells 1 can use a secondary battery cell having an outer can 1b in a square or cylindrical shape. Figure 7 , Figure 8 In the example shown, four cylindrical secondary battery cells 1 are arranged in a posture of stacking two layers with two cells per layer. In addition, the secondary battery cells 1 are set to be connected in two series and two full parallel connections. In addition, the number, configuration, number of series or parallel connections of the secondary battery cells are not limited to this example, and any number and configuration can be appropriately adopted. Each secondary battery cell 1 has a positive and negative electrode. The positive and negative electrodes are preferably provided on one end surface 1c of the secondary battery cell 1. For such a secondary battery cell 1, known secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries can be appropriately utilized.

[0069] In addition, the secondary battery cell 1 has a safety mechanism that releases the internal gas from the outer can 1b when the internal pressure of the outer can 1b increases for some reason. Figure 8 As shown in the figures, a gas outlet 1a is provided in the outer tank 1b of the secondary battery cell 1. The gas outlet 1a opens in response to the increase in the internal pressure of the outer tank 1b, and releases the gas inside the outer tank 1b to the outside. Such a gas outlet 1a can utilize, for example, a safety valve or a sealing body provided with a cutout that opens the open end. The gas outlet 1a is surrounded by a battery holder 20. Therefore, the gas released from the gas outlet 1a flows toward the end face 1c of the secondary battery cell 1. In addition, the gas outlet 1a can also be formed into a circular arc-shaped slit when viewed from above the end face 1c. Furthermore, a plurality of gas outlets 1a can be provided. In the later-described Fig.14 , Fig.16 In the example shown in FIG. 1 and FIG. 2 , three gas exhaust ports 1 a formed in a slit shape are opened in an arc shape.

[0070] (Lead plate 30)

[0071] A lead plate 30 is disposed on the side surface of the battery holder 20. The lead plate 30 connects the electrodes on the end surfaces 1c of the secondary battery cells 1 to each other, and connects the plurality of secondary battery cells 1 in series or in parallel. Figure 3 to Figure 7 In the example of, the secondary battery cells 1 are set to be connected in series with two and in parallel, and a first lead plate 31 is provided to connect the end faces 1c of the four secondary battery cells 1 to each other, and a second lead plate 32 is provided to connect the end faces 1c of the two secondary battery cells 1 to each other. In addition, the number, configuration, number of connections in series or in parallel, etc. of the secondary battery cells are not limited to this example, and any number and configuration can be appropriately adopted. These lead plates 30 are made of metal plates with excellent conductivity such as nickel plates. In addition, an insulating plate can also be arranged on the end face of the lead plate 30 as needed. The insulating plate is made of a material with excellent insulation such as paper and mica.

[0072] like Figure 3 to Figure 7 As shown, each lead plate 30 has a pair of bonding pieces 34 respectively bonded to the end faces 1c of the adjacent secondary battery cells 1, and a flat portion 35 with the pair of bonding pieces 34 provided on both sides. The flat portion 35 has the pair of bonding pieces 34 bent on both sides. Figure 8 As shown, the main surface of the plane portion 35 is separated from the surfaces to which the pair of joining pieces 34 belong, and a first space 36 is formed on the back side of the plane portion 35 .

[0073] (Fuse structure 38)

[0074] also, Figure 7 The first lead plate 31 shown has a fuse structure 38 that breaks when a current exceeding a given value flows. The fuse structure 38 increases the resistance value by locally providing a narrow width region in a portion of the lead plate 30. As a result, it can function as a temperature fuse in which the narrow width region of the lead plate 30 is melted by Joule heat when a large current flows. This fuse function can determine that an abnormality occurs when a large current exceeding a given value flows, and the fuse is melted to cut off the current, thereby improving the safety of the battery pack.

[0075] On the other hand, consider the following situation: due to some abnormality in any of the secondary battery cells, the internal pressure of the outer can increases, and the safety mechanism is activated to release high-temperature and high-pressure gas from the gas outlet. Fig. 9In the structure of the battery pack 900 involving the comparative example shown in the stereoscopic view of the , the lead plate 930 is used for the electrical connection of the secondary battery cells 901. The battery holder 920 holds the secondary battery cells 901 in a posture where the end faces of the secondary battery cells 901 are aligned, and the end faces of the adjacent secondary battery cells 901 are exposed, and the lead plates 930 are used for welding and connection. In this structure, the flat lead plates 930 are welded to cover the end faces of the secondary battery cells 901. As a result, Fig.10 As shown in the cross-sectional view of , the end face on the positive electrode side is covered by the lead plate 930. On the other hand, each secondary battery cell 901 is provided with a safety valve or the like, which opens the valve to discharge the high-temperature and high-pressure gas inside the outer can to the outside in the event that the inside of the outer can becomes high pressure. Such a gas discharge port 901a is generally provided on the end face on the positive electrode side.

[0076] In such a structure, when high-temperature and high-pressure gas is discharged from the gas discharge port 901a, Fig.11 As shown in the cross-sectional view of , the lead plate 930 is directly exposed to the high-temperature and high-pressure gas, which may cause the following situation: the lead plate 930 is damaged or broken, the resistance value of the circuit increases, and the current does not flow. As a result, since the current does not flow, the fuse structure 938 provided in the lead plate 930 does not operate properly, and the secondary battery cell 901B is energized in other parts, and there is a possibility of thermal runaway propagation. This situation has been determined through experiments by the inventors of the present application.

[0077] (Path defining unit 25)

[0078] In order to avoid such a situation, the battery pack 100 according to the present embodiment includes a path defining portion 25 defining a gas discharge path 40, and the gas discharge path 40 guides the gas so that the high-temperature and high-pressure gas discharged from the gas discharge port 1a is not directly irradiated to the lead plate 30. The gas discharge path 40 is provided with a first path 41 and a second path 42. The first path 41 is a gas discharge path 40 along a first direction from the center direction of the circular shape of the end surface 1c of the outer can 1b to the circumferential direction. On the other hand, the second path 42 is a gas discharge path 40 along a second direction from the circumferential direction of the circular shape of the end surface 1c of the outer can 1b to the center direction opposite to the first path 41. By setting such a structure, even if high-temperature and high-pressure gas is discharged from the gas discharge port 1a of any secondary battery cell, it can be guided to the gas discharge path 40 to reduce the pressure, so that the amount of high-temperature and high-pressure gas directly discharged to the lead plate 30 side can be reduced to improve safety.

[0079] Such a path defining portion 25 can be provided in the battery holder 20. Fig.12 , Fig.13 , Fig.14 , Fig.15 , Fig.16 , Fig.17 In the illustrated example, a baffle 26 and a wall portion 27 are formed as a path defining portion 25 on the inner surface of the battery holder 20 that faces the end surface 1 c of the secondary battery cell 1 .

[0080] (Baffle 26)

[0081] The baffle plate 26 is a member extending between the center direction and the circumferential direction of the circular shape of the end surface 1c of the outer can 1b. It is preferable to provide a plurality of baffle plates 26. Fig.17 In the example of FIG. 1 , seven baffles 26 are provided on the inner surface of the battery holder 20 radially from the center of the circular secondary battery cell 1. Each baffle 26 has a first path 41 on one side surface along the extending direction and a second path 42 on the other side surface.

[0082] (Wall 27)

[0083] In addition, the wall portion 27 is formed separately from each baffle plate 26. Fig.17 In the example of FIG. 1 , the wall portion 27 is formed into a mountain shape along the outer edge of each radial baffle 26. Between each baffle 26 and the wall portion 27, a gas exhaust path 40 is formed. Fig.18 , Fig.19 The gas discharge path 40 is formed in a U-shape. In addition, the gas discharge path 40 has a star-shaped or petal-shaped undulating shape. The baffle 26 and the wall 27 are preferably formed integrally on the inner surface of the battery holder 20. Thus, the path defining portion 25 can be added at a low cost.

[0084] Each baffle 26 has a first end face 26a and a second end face 26b as end faces in the longitudinal direction. Fig.17 As shown in the figure, the first end face 26a faces the central side of the circular shape of the end face 1c of the outer can 1b. In addition, the second end face 26b faces the opposite side of the first end face 26a, that is, the circumferential side of the circular shape of the end face 1c of the outer can 1b. The first path 41 and the second path 42 are respectively provided on both sides of the length direction extending between the first end face 26a and the second end face 26b. Fig. 20 In the example shown in the enlarged view of , the right side is set as the first path 41, and the left side is set as the second path 42. Furthermore, on both sides of the first end surface 26a, a first guide port 44 communicating with the first path 41 and a second guide port 45 communicating with the second path 42 are opened respectively. Fig. 20In the example of FIG. 4 , the right side of the first end surface 26a is the first guide port 44, and the left side is the second guide port 45. In addition, a communication portion 43 that allows the first path 41 and the second path 42 to communicate is formed on the second end surface 26b side.

[0085] Here, the first path 41 is defined so that the opening width is narrowed from the first guide port 44 toward the second end face 26b side. In addition, the second path 42 is defined so that the opening width is narrowed from the second guide port 45 toward the second end face 26b side. By setting such a structure, the high-temperature and high-pressure gas guided from either the first guide port 44 or the second guide port 45 has a faster flow rate and a reduced pressure due to the gradual reduction of the flow path area. Thereafter, when it goes to the second guide port 45 or the first guide port 44, it expands due to the expansion of the flow path area, thereby becoming a reverse pressure gradient state in which the pressure rises instead. As a result, the pressure loss can be increased and the pressure of the gas can be reduced. In addition, the opening width of the connecting portion 43 is formed narrower than the first guide port 44 and the second guide port 45.

[0086] The open end of the gas outlet 1a formed by the first guide port 44 and the second guide port 45 is arranged to face any one of the gas outlets 1a. Thus, the high-temperature and high-pressure gas can be guided from both or any one of the first guide port 44 and the second guide port 45 to the first path 41 and / or the second path 42, and the flow path of the gas outlet path 40 can be lengthened, and the momentum is lost by changing the traveling direction at the connecting portion 43 between the first path 41 and the second path 42, so that the pressure of the gas is reduced. In addition, by setting the baffle 26 in a radial shape, the gas can generate pressure loss to reduce the total pressure when irradiated to the lead plate 30, thereby reducing the damage to the lead plate 30.

[0087] Here, in Fig.21 The graph shows the battery pack 100 according to the first embodiment and the battery pack 100 according to the comparative example. Fig. 9 , Fig.10 The pressure change of the gas in the battery pack 900 shown in the figure without the path defining portion 25 is shown. In the figure, the static pressure is shown by the solid line, and the dynamic pressure is shown by the dotted line. As shown in the figure, it can be seen that in the comparative example, the static pressure and the dynamic pressure do not change, but in the battery pack 100 involved in the first embodiment, the static pressure and the dynamic pressure are reduced. Specifically, if the high-temperature and high-pressure gas flows into the first guide port 44, the static pressure is converted into dynamic pressure as it goes to the connecting portion 43. In addition, after passing through the connecting portion 43, the pressure recovery occurs with the expansion of the flow path, and the dynamic pressure is converted into static pressure, but the flow of the gas does not follow the shape of the flow path, and the flow is stripped, so that pressure loss occurs and the pressure is reduced.

[0088] Furthermore, by guiding the gas from both the first guide port 44 and the second guide port 45, it is possible to cause high-pressure gases to collide with each other in the middle of the gas guide path to generate vortexes and achieve pressure reduction. Fig.18 As shown in FIG. 1 , when the gas outlet 1a is opposed to only the first guide port 44 formed on the side of the baffle plate 26 on the lower side in the figure, the amount of gas flowing from the first guide port 44 to the second guide port 45 becomes larger. In addition, when the gas outlet 1a is opposed to only the second guide port 45 formed on the side of the baffle plate 26 on the upper side in the figure, the amount of gas flowing from the second guide port 45 to the first guide port 44 becomes larger. On the other hand, Fig.19 As shown, when the first guide port 44 and the second guide port 45 are both opposed to the gas discharge port 1a, the gas is guided to the first guide port 44 and the second guide port 45 respectively, resulting in collision of the gas inside the first path 41 and the second path 42, resulting in pressure attenuation.

[0089] Furthermore, the first guide port 44 and the second guide port 45 are preferably defined by a curved surface. By setting such a structure, it is possible to prevent pressure loss from occurring in the first guide port 44 and the second guide port 45, and to facilitate the gas to be guided to the gas discharge path 40. On the contrary, if the first guide port 44 and the second guide port 45 are formed in a straight line or a corner of a triangle or the like, pressure loss occurs at these inlet portions, causing turbulence, and as a result, it is difficult to guide the gas.

[0090] In this way, by generating pressure loss by the path defining portion 25 , the mass flow rate of the gas reflected by the lead plate and flowing into the adjacent secondary battery cell side is reduced, thereby expecting an effect of reducing the risk of fire spread.

[0091] (Example)

[0092] Here, as an example, Fig. 22 The graph shows that Fig. 20 FIG. 4 is an image showing a change in flow velocity when the gas guided by the first guide port 44 passes through the communicating portion 43 and is discharged from the second guide port 45 .

[0093] In the above example, the open end of the gas exhaust port 1a formed by the first guide port 44 and the second guide port 45 is configured to face any one of the gas exhaust ports 1a. Here, the plurality of baffles 26 are configured to be separated from each other by a first distance. In addition, the plurality of gas exhaust ports 1a are separated from each other by a second distance. Here, the first distance is different from the second distance. In addition, m, which is the number of gas exhaust ports 1a provided, and n, which is the number of baffles 26 provided, are mutually prime. By setting such a structure, regardless of the rotational orientation of the secondary battery cell 1, the first guide port 44 and the second guide port 45 defined by the baffle 26 and the gas exhaust port 1a must be opposed at any position, so that high-temperature and high-pressure gas can be reliably guided to the first guide port 44 and the second guide port 45. As a result, there is no need to position the rotational orientation of the secondary battery cell 1 and the relative position of the baffle 26 in the assembly process of the battery pack, and the advantage of being able to simplify the assembly process of the battery pack can be obtained. Fig.14 , Fig.16 In the example, the gas outlet 1a is set to three slits and seven baffles 26 are provided. If the gas outlet 1a and the baffle 26 are designed to be mutually prime in this way, a portion where the gas outlet 1a and the baffle 26 are opposed to each other will definitely be generated at any position on the circumference. Therefore, even if the posture of the secondary battery cell 1 in the rotation direction is not positioned, any gas outlet 1a can be opposed to any baffle 26, that is, the gas outlet path 40, to achieve the protection of the lead plate 30 caused by the pressure drop during gas discharge. In addition, the path defining portion 25 can also be formed to be point-symmetrical with respect to the center of the circle of the end face 1c of the outer tank 1b. Similarly, the gas outlet 1a can also be formed to be point-symmetrical with respect to the center of the circle of the end face 1c of the outer tank 1b.

[0094] [Implementation Method 2]

[0095] On the other hand, the present disclosure is not limited to the structure in which the gas outlet and the baffle are designed to be different prime numbers. As long as the gas outlet and the baffle are relatively positioned, they can also be set to any number other than a prime number. Fig.23 Shown in Fig.23 The battery pack according to the second embodiment shown in the figure. In this figure, the same symbols are marked for the same components as those in the first embodiment, and detailed descriptions are omitted as appropriate. In the battery pack according to the second embodiment, the number of gas outlets 1a is set to 3 as in the first embodiment, and the number of baffles 26B is set to 6 instead of a prime number. Even with such a structure, by relative positioning of the gas outlet 1a and the baffle 26B, it is possible to set the position where the gas outlet 1a and the baffle 26B are opposite to each other, thereby utilizing the path defining portion to reduce the pressure when the gas is discharged and protect the lead plate.

[0096] [Implementation method 3]

[0097] In addition, the path defining unit is not limited to the above-mentioned structure, and other modes can also be adopted. Fig.24 The battery pack involved in Embodiment 3 is shown in FIG. In this figure, the same symbols are also marked for the same components as those in Embodiment 1 and the like, and detailed descriptions are appropriately omitted. In the battery pack shown in this figure, as a path defining portion 25, in addition to forming a wall portion 27B along the outer shape of the above-mentioned baffle 26B, the connecting portions 43B are connected to each other through an annular path. Here, the annular path is set to a circular annular path 47. If it is this structure, the gas reaching the connecting portion 43B from the first guide port 44B and the second guide port 45B is also branched in the annular path 47, and is also guided to the first path 41B and the second path 42B formed around other adjacent baffles 26B. As a result, the number of collisions with the gas guided from other baffles 26B increases, and the pressure of the gas is further reduced. In addition, in the structure of embodiment 1, there is a baffle 26 that is not opposite to the gas exhaust port 1a, and this portion is not fully utilized. However, in the structure of embodiment 3, the gas also flows through the annular path 47 in the first path 41B and the second path 42B formed by the baffle 26B that is not opposite to the gas exhaust port 1a, thereby being able to fully utilize the gas pressure reduction effect of the entire baffle 26B.

[0098] [Implementation Method 4]

[0099] Furthermore, such an annular path connecting the communicating parts to each other is not limited to a circular structure, and may be set to other shapes. Fig.25 2 shows a battery pack according to Embodiment 4. In this figure, the same reference numerals are given to the same components as those in Embodiment 1, and detailed descriptions are omitted as appropriate. The battery pack shown in this figure has the communication portions 43C connected to each other by a ring-shaped corrugated path 48, as in Embodiment 2. The corrugated path 48 is connected to each other by a ring-shaped corrugated path 48. Fig.24 In the path defining portion 25, the annular path is bent in the region between the baffles 26C, which is originally a dead angle, to further enhance the pressure reducing effect.

[0100] [Implementation method 5]

[0101] In addition, the above-mentioned third and fourth embodiments may be combined to form a looped path using both a circular path and a corrugated path. Such an example is used as a battery pack according to the fifth embodiment. Fig.26, in which the same reference numerals are used for the same components as those in the first embodiment and the detailed description is omitted as appropriate. In the battery pack shown in the figure, a first guide port 44D and a second guide port 45D are also provided between the baffle 26D and the wall portion 27D, and a first path 41D and a second path 42D are connected through a connecting portion 43D. Furthermore, a corrugated path 48D similar to that in the fourth embodiment is provided in the middle of the annular annular path 47D similar to that in the third embodiment passing through the connecting portion 43D to branch. With this structure, the annular path can be further branched, so that the pressure loss at the confluence portion can be increased and the gas pressure reduction effect can be further improved.

[0102] [Implementation Method 6]

[0103] Furthermore, in the above-mentioned embodiments 3 and 4, the width of the looped path is described as being fixed, but it is also possible to set the path to have an uneven width with a narrow portion having a narrow width. Such an example is used as a battery pack according to the sixth embodiment. Fig. 27 . In this figure, the same symbols are also marked for the same components as those in the above-mentioned embodiment 1, and detailed descriptions are appropriately omitted. In the battery pack shown in this figure, a first guide port 44E and a second guide port 45E are also provided between the baffle 26E and the wall portion 27E. In addition, the first path 41E and the second path 42E are connected through the connecting portion 43E. Furthermore, the width of the annular annular path 47E passing through the connecting portion 43E is changed at each position to make it uneven. In this way, the pressure loss can be further increased.

[0104] In the above examples, the battery pack is mounted on the electrical device of the driving object to supply power to the electrical device. In addition, when the remaining capacity of the battery pack decreases or when the battery pack deteriorates over the years, the battery pack can be replaced to continue using the electrical device. However, the present disclosure does not limit the battery pack to a replaceable battery pack that mainly accommodates secondary battery cells, but can also be applied to a method in which a secondary battery cell is accommodated in the housing of the electrical device. In the present disclosure, a so-called battery pack is one that accommodates a secondary battery cell in the housing, and a structure in which a secondary battery cell for driving is built into the housing of the electrical device itself is also referred to as a battery pack. That is, the present disclosure is not limited to replaceable battery packs, but can also be applied to electrical devices with built-in secondary battery cells.

[0105] Industrial Applicability

[0106] The battery pack of the present invention can be suitably used as a driving power source for autonomous robots for delivery, electric carts for delivery and golf courses, electric scooters, construction machinery, hybrid vehicles, electric vehicles, etc. In addition, in addition to the driving power source for power-assisted bicycles, it can also be appropriately used as a power source for portable electrical equipment such as wireless devices, electric cleaners, and electric tools, as a backup power source for servers for stationary power storage purposes, and as a power supply device for home use, production service sites, and factories.

[0107] Description of Reference Numerals

[0108] 100…Battery pack

[0109] 1… secondary battery cell; 1a… gas outlet; 1b… outer container; 1c… end surface

[0110] 2…Battery Module

[0111] 3…Circuit board

[0112] 10…External housing

[0113] 11…Upper housing

[0114] 12…Lower housing

[0115] 20…Battery holder

[0116] 21 ... first retaining member

[0117] 22 ... second retaining member

[0118] 23…Opening

[0119] 24…Storage tube

[0120] 25…Route regulation unit

[0121] 26, 26B, 26C, 26D, 26E... baffle; 26a... first end surface; 26b... second end surface

[0122] 27, 27B, 27D, 27E…Wall

[0123] 30...Lead plate

[0124] 31…first lead plate

[0125] 32…Second lead plate

[0126] 34…Joint piece

[0127] 35…Flat surface

[0128] 36…First Space

[0129] 38…Fuse structure

[0130] 40…Gas exhaust path

[0131] 41, 41B, 41D, 41E…First Path

[0132] 42, 42B, 42D, 42E… Second Path

[0133] 43, 43B, 43C, 43D, 43E…connecting part

[0134] 44, 44B, 44D, 44E…first guide port

[0135] 45, 45B, 45D, 45E…Second guide port

[0136] 47, 47D, 47E…Circular Path

[0137] 48…Wave Path

[0138] 900…Battery pack

[0139] 901, 901A, 901B… secondary battery cells; 901a… gas outlet

[0140] 920…Battery holder

[0141] 938…Fuse construction.

Claims

1. A battery pack comprising: A plurality of secondary battery cells, wherein the outer can is set to be cylindrical, and one or more gas exhaust ports are provided on the circular end surface of the outer can; an outer casing for housing the plurality of secondary battery cells; and One or more lead plates are connected to the end surface of any one of the plurality of secondary battery cells. The battery pack includes: a path defining unit that defines a gas exhaust path disposed to face at least any one of the one or more gas exhaust ports; The path defining portion defines a first path and a second path, wherein the first path is along a first direction from the center direction of the circular end surface of the outer can toward the circumferential direction, and the second path is along a second direction from the circumferential direction of the circular end surface of the outer can toward the center direction.

2. The battery pack according to claim 1, wherein: The lead plate has a fuse structure that breaks when a current exceeding a given value flows.

3. The battery pack according to claim 1, wherein: The battery pack further includes a battery holder for holding the plurality of secondary battery cells. The path defining portion is formed on an inner surface of the battery holder that faces an end surface of the secondary battery cell.

4. The battery pack according to claim 1, wherein: The path defining portion includes one or more baffles extending between the center direction and the circumferential direction of the circular shape of the end surface of the outer can. The first path is provided on one side surface of the one or more baffles along the extension direction, and the second path is provided on the other side surface, and A first guide port communicating with the first path and a second guide port communicating with the second path are respectively opened on both sides of a first end face of the one or more baffles facing the circular center side face of the end face of the outer can. The first path and the second path are communicated with each other on the second end surface side of the one or more baffles that faces the circular circumferential side of the end surface of the outer can.

5. The battery pack according to claim 4, wherein: The first path is defined so that the opening width becomes narrower from the first guide port toward the second end surface side. The second path is defined so that the opening width becomes narrower from the second guide port toward the second end surface side.

6. The battery pack according to claim 4, wherein: The first guide opening and the second guide opening are defined by a curved surface.

7. The battery pack according to claim 4, wherein: A plurality of baffles are provided.

8. The battery pack according to claim 7, wherein: The plurality of baffles are arranged to be separated by a first distance that is equally spaced from each other. The one or more gas exhaust ports include a plurality of gas exhaust ports that are spaced apart from each other by a second distance that is equal to or different from the first distance.

9. The battery pack according to claim 8, wherein: The number m of the gas exhaust ports and the number n of the baffles are relatively prime.

10. The battery pack according to claim 8, wherein: The baffles are arranged radially with respect to the center of the circular shape of the end surface of the outer can. The path defining portion includes a wall portion that is separated from the radial baffle plate and formed in a mountain shape along an outer edge of the baffle plate, and the gas exhaust path is formed in a U shape between the wall portion and the baffle plate.

11. The battery pack according to claim 10, wherein: The opening width between the second end surface of each baffle plate and the wall portion is formed to be narrower than the first guide opening and the second guide opening.

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