Battery pack

Abstract

A battery pack (1) in which a plurality of batteries (30) are housed in a case (10), the plurality of batteries (30) having a relief valve (37) that opens by an increase in internal pressure and discharges internal gas, and the plurality of batteries (30) are immersed in a coolant (50) in the case (10). The case (10) is provided with: a gas inflow part into which the gas discharged from the battery (30) flows; an exhaust part (13) which is provided on a wall part of the case (10) and which exhausts the gas exhausted from the battery (30) to the outside of the case (10); and an exhaust path (16) provided between the gas inflow part and the exhaust part (13) and including a reservoir (18) for the cooling liquid or an inner reservoir path provided in the reservoir (18).

Description

Technical Field

[0001] The present invention relates to a battery pack in which a plurality of batteries are housed. Background Art

[0002] Secondary batteries such as lithium ion batteries are used in the form of a battery pack in which a plurality of batteries are electrically connected and housed in a case. In Patent Document 1, a battery pack is disclosed in which batteries are housed in a space filled with a coolant to cool the batteries.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-60088 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In addition, when an abnormality occurs in a battery within a battery pack, heat is generated inside the battery, and the surface of the outer case of the battery becomes high temperature. Moreover, if the abnormality further progresses, high-temperature gas will soon be generated from inside the battery. In the battery pack disclosed in Patent Document 1, a structure in which the battery has a safety valve that opens by an increase in internal pressure and discharges the internal gas is considered. In addition, a structure in which the gas discharged from the safety valve is discharged to the outside of the case via an exhaust portion provided in the upper space within the case is also considered. However, in this structure, there is a possibility that the high-temperature gas is discharged to the outside of the case without being cooled. Therefore, problems may occur when the gas is flammable. Accordingly, it is desired to reduce the gas temperature when discharging the gas to the outside of the case.

[0008] An object of the present invention is to provide a battery pack capable of reducing the gas temperature when discharging gas generated inside the battery to the outside of the case when an abnormality occurs in the battery.

[0009] A battery pack according to one aspect of the present invention houses a plurality of batteries in a case. Among them, the plurality of batteries have safety valves that open by an increase in internal pressure and discharge the internal gas, and the plurality of batteries are immersed in a coolant within the case. The case includes: a gas inlet portion provided within the case for allowing the gas discharged from the battery to flow in; an exhaust portion provided in the wall portion of the case for discharging the gas discharged from the battery to the outside of the case; and an exhaust path provided between the gas inlet portion and the exhaust portion, including a coolant accumulation portion or an accumulation portion internal path provided within the accumulation portion.

[0010] According to a battery pack of one aspect of the present invention, when an abnormality occurs in the battery, the gas generated inside the battery passes through the coolant accumulation portion or the accumulation portion internal path within the case, and thus the gas temperature when discharging the gas to the outside of the case can be reduced. Brief Description of the Drawings

[0011] Figure 1 This is a perspective view of a battery pack as an example of an embodiment.

[0012] Figure 2 This is Figure 1 a sectional view taken along line A-A.

[0013] Figure 3 This is a sectional view of the battery that constitutes the battery pack of the embodiment.

[0014] Figure 4 This is a view corresponding to Figure 2 of a battery pack of another example of the embodiment.

[0015] Figure 5 This is a view corresponding to Figure 2 of a battery pack of another example of the embodiment.

[0016] Figure 6 In (a) of Figure 2 is a view corresponding to Figure 6 of a battery pack of another example of the embodiment, Figure 6 and (b) of is an enlarged view of part B of (a) of

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, among the multiple drawings, there are schematic diagrams, and the dimensional ratios of the lengths, widths, heights, etc. of each component may not be the same between different drawings. In addition, for the components described below that are not described in the independent claims representing the most general concept, they are optional components, not essential components.

[0018] In addition, in the following embodiments, the case where the battery pack 1 has a substantially rectangular parallelepiped outer shape will be described as an example. In the drawings and the description of the embodiments, the X direction represents the length direction of the battery pack 1 (housing 10), the Y direction represents the width direction of the battery pack 1 (housing 10), and the Z direction represents the up-and-down direction (height direction) of the battery pack 1 (housing 10). The X direction, Y direction, and Z direction are orthogonal to each other. In addition, in the Z direction, Figure 3 the side of the battery 30 shown in

[0019] with the lid 45 is set as the "upper side", and the opposite side is set as the "lower side". The Z direction, that is, the up-and-down direction, corresponds to the first direction. The X direction, that is, the length direction, corresponds to the second direction. Figure 1 and Figure 2 will be used to explain the outline of the battery pack 1. Figure 1 This is a perspective view of the battery pack 1 as an example of an embodiment. Figure 2 This is Figure 1AA cross-sectional view (a cross-sectional view when cutting along an XZ plane passing through the center in the width direction of the battery pack 1).

[0020] The battery pack 1 includes a battery block 20 having a plurality of batteries 30 and a housing 10 for housing the battery block 20. For example, a non-aqueous electrolyte secondary battery such as a lithium ion battery is used as the battery 30. Although the shape and size are not particularly limited, a cylindrical battery is preferred. The following description will focus on the case where the battery 30 is a cylindrical battery.

[0021] The housing 10 is a box-shaped body having a substantially rectangular parallelepiped shape. An insulating coolant 50 is stored inside the housing 10, and each battery 30 is partially immersed in the coolant 50. Thus, the coolant 50 is in direct contact with each battery 30, thereby improving the cooling performance of each battery 30.

[0022] A gas inflow chamber 12 is provided inside the housing 10 as a portion into which high-temperature and high-pressure gas discharged from the inside of the battery 30 flows when an abnormality occurs in the battery 30. An exhaust portion 13 for exhausting the gas in the battery 30 to the outside of the housing 10 is provided on the wall portion of the housing 10 facing the outside. An exhaust path 16 is provided inside the housing 10 between the gas inflow chamber 12 and the exhaust portion 13. In the present embodiment, the exhaust path 16 includes a reservoir 18 for the coolant 50. Thus, as described later, when an abnormality occurs in the battery 30, the gas generated from the inside of the battery 30 passes through the reservoir 18 of the coolant 50 in the housing 10, thereby being able to reduce the gas temperature when the gas is discharged to the outside of the housing 10.

[0023] The battery pack 1 is mainly used as a power source for power. For example, the battery pack 1 is used as a power source for electric devices driven by electric motors, such as electric vehicles, electric tools, electric assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric vehicles for the elderly. In addition, the use of the battery pack 1 is not particularly limited, and it can also be used as a power source for various electric devices used indoors and outdoors, such as cleaners, wireless devices, lighting devices, digital cameras, and video cameras, etc., other than electric devices.

[0024] The battery block 20 includes a plurality of batteries 30 and a battery holder 60 for inserting and holding both ends of the batteries 30 in the vertical direction Z. The battery block 20 is arranged in the portion from the lower end to the middle portion in the vertical direction Z inside the housing 10. Thus, a gas inflow chamber 12 described later is formed at the upper end inside the housing 10. The gas inflow chamber 12 corresponds to the gas inflow portion.

[0025] The battery 30 has a safety valve 37 which opens when the internal pressure rises and discharges the internal gas. In the present embodiment, the safety valve 37 is provided at the upper end of the battery 30, which will be described in detail later. Specifically, with the first direction being the vertical direction, a plurality of batteries 30 are arranged in the housing 10 in the vertical direction such that the safety valve 37 is located at the upper end which is one end side in the first direction. If the internal pressure of the battery 30 rises when an abnormality occurs in the battery 30, gas will be discharged from the exhaust hole 45a formed in the lid 45 constituting the safety valve 37 (refer to Figure 3 ).

[0026] The battery holder 60 includes a first holder 61 that holds the upper side of the battery 30 and a second holder 62 that holds the lower side of the battery 30. The first holder 61 includes: a holding portion 63 that holds the upper end of the battery 30; and an opening 64 into which the lid 45 of the battery 30 is inserted to expose the lid 45 to the gas inlet chamber 12. The lid 45 constitutes the safety valve 37 of the battery 30.

[0027] Refer to Figure 1 and Figure 2 for a detailed description of the housing 10.

[0028] The housing 10 is made of a metal such as aluminum or a resin and has a substantially rectangular parallelepiped shape. Specifically, the housing 10 has two first side walls 10a, 10b disposed at both ends in the length direction X and two second side walls 10c disposed at both ends in the width direction Y. Each of the side walls 10a, 10b, 10c corresponds to a wall portion. The housing 10 has a function of protecting the battery 30 housed inside from the influence of dust and water.

[0029] As Figure 2 shown, a battery accommodation chamber 11 for accommodating the battery 30 is formed inside the housing 10. The battery accommodation chamber 11 is a portion partitioned by the housing 10, the first holder 61, and the second holder 62, and is a portion where parts of the battery 30 other than both ends in the vertical direction Z are arranged. Coolant 50 accumulates in the battery accommodation chamber 11, and parts of each battery 30 are immersed in the coolant 50. From the viewpoint of efficiently cooling the battery 30, as Figure 2 shown, it is preferable that the coolant 50 occupies more than half of the volume of the battery accommodation chamber 11. The coolant 50 may also be filled in the entire battery accommodation chamber 11. In this way, the battery 30 is in contact with the coolant 50 and is directly cooled, so that the battery 30 can be efficiently cooled. Thereby, the charging performance, durability, and safety of the battery 30 can be improved.

[0030] In addition, the coolant 50 has insulating properties. Thereby, it is possible to prevent the battery 30 from leaking electricity to other batteries 30 via the coolant 50. Examples of the coolant 50 include insulating oils, transformer oils, silicone oils, fluorine-based inert liquids such as hydrofluoroethers, and the like.

[0031] As Figure 2 shown, a gas inflow chamber 12 into which the gas discharged from the safety valve 37 of the battery 30 flows is formed at the upper side end portion inside the housing 10. The gas inflow chamber 12 is formed between the top plate of the housing 10 and the first holding member 61 so as to be separated from the battery accommodation chamber 11. The lid 45 constituting the safety valve 37 is exposed to the gas inflow chamber 12. Thus, the upper end portions, i.e., the safety valve 37 side end portions, of the plurality of batteries 30 are exposed to the gas inflow chamber 12. When the pressure inside the battery 30 rises in the event of an abnormality in the battery 30, the gas generated inside the battery 30 is discharged from the exhaust hole 45a of the lid 45 (refer to Figure 3 ), which will be described in detail later. Thus, the gas discharged from the safety valve 37 flows into the gas inflow chamber 12.

[0032] The housing 10 has an exhaust portion 13 provided on the upper side of the first side wall 10a provided at one end in the length direction as the second direction. The exhaust portion 13 discharges the gas inside the gas inflow chamber 12 to the outside of the housing 10. Thus, the gas discharged from the safety valve 37 of the battery 30 when an abnormality occurs in the battery 30 is discharged from the exhaust portion 13 to the outside of the housing 10.

[0033] The size of the exhaust portion 13 is only required to be such that it can discharge the gas inside the housing 10 and suppress the breakage of the housing 10, and there is no particular limitation. The exhaust portion 13 may be always open, or may be a structure having a function of breaking and opening according to the rise in the pressure inside the housing 10 in the event of an abnormality. Thus, it is possible to prevent dust and water from entering the inside of the housing 10, or coolant from leaking to the outside of the housing 10, and to suppress the breakage of the housing 10.

[0034] In the present embodiment, the exhaust portion 13 is formed by a plurality of small holes penetrating the first side wall 10a and approaching each other. The exhaust portion may also be formed by only one small hole or a slit. By having a slit, in the event of an abnormality, the slit portion will preferentially deform according to the rise in the pressure inside the housing 10. Thus, when the gas is discharged from the safety valve 37, the pressure inside the housing 10 rises, and the exhaust portion is pressed from the inside of the housing 10, so that the slit portion opens and discharges the gas to the outside of the housing 10. In addition, the slit refers to a through hole that penetrates in the thickness direction of each exhaust portion and has a thin wire cross-section.

[0035] The housing 10 may also have a covering member that covers the exhaust portion 13. Thus, it is possible to further suppress dust and water from entering the inside of the housing 10. The covering member is fixed to the outer surface or the inner surface of the housing 10 by a fixing member such as an adhesive so as to block the exhaust portion 13. The covering member may also be made of a breathable waterproof material such as GORE-TEX (registered trademark) that allows the exhaust from the inside of the housing 10 to pass through and blocks liquids such as water from the outside.

[0036] In addition, inside the housing 10, an exhaust path 16 is provided between the gas inflow chamber 12 and the exhaust portion 13. In the present embodiment, the exhaust path 16 includes an accumulation portion 18 for the coolant 50 in the middle portion in the path direction. The accumulation portion 18 will be described in detail later.

[0037] Refer to Figure 2 The battery block 20 will be described. As described above, the battery block 20 has a battery holder 60 into which both axial ends of a plurality of batteries 30 are inserted and held.

[0038] The battery block 20 includes a positive terminal plate 70 that abuts against the upper surface of the first holder 61 and a negative terminal plate 80 that abuts against the lower surface of the second holder 62. The positive terminal plate 70 and the lid 45, which is the positive external terminal of the battery 30, are electrically connected by a positive lead portion (not shown). In addition, the negative terminal plate 80 is electrically connected to the bottom of the outer casing 35 (refer to Figure 3 ) which is the negative external terminal of the battery 30 by a negative lead portion (not shown). The positive terminal plate 70 and the negative terminal plate 80 connect the plurality of batteries 30 in parallel.

[0039] The battery holder 60 can also be made of, for example, PC (polycarbonate) resin, highly heat-conductive PPS (polyphenylene sulfide) resin, resin containing a heat-dissipating filler, a thermosetting resin capable of injection molding, etc. More specifically, the battery holder 60 can also be made of phenolic resin, unsaturated polyester, or unsaturated polyester mixed with an endothermic agent.

[0040] The holding portion 63 of the first holder 61 is a circular hole portion formed on the lower surface of the first holder 61. By fitting the upper end portion of the battery 30 into the holding portion 63, the upper side of the battery 30 is held.

[0041] The opening 64 is formed to penetrate the first holder 61 in the vertical direction. More specifically, the opening 64 is formed as a circular hole having the same central axis as the holding portion 63 and a diameter smaller than that of the holding portion 63. By forming the opening 64, the lid 45, which is the positive external terminal of the battery 30, can be exposed to the gas inflow chamber 12, so that the lid 45 can be connected to the positive lead portion. In addition, when an abnormality occurs in the battery 30, the gas discharged from the safety valve of the battery 30 can flow into the gas inflow chamber 12. The above-mentioned positive lead portion is connected to the lid 45 of the battery 30 through the opening 64. The positive lead portion can also be a part integrally formed with the positive terminal plate 70.

[0042] The second holding member 62 includes a holding portion 65 that holds the lower end portion of the battery 30 and an opening portion 66 that exposes the bottom surface of the battery 30 toward the bottom plate side of the housing 10. The holding portion 65 of the second holding member 62 is a circular hole portion formed on the upper side surface of the second holding member 62. By fitting the lower end portion of the battery 30 into the holding portion 65, the lower side of the battery 30 is held.

[0043] The opening portion 66 is formed to penetrate the second holding member 62 in the vertical direction. The negative electrode lead portion is connected to the bottom of the battery 30 through the opening portion 66. The negative electrode lead portion may also be a portion integrally formed with the negative terminal plate 80.

[0044] Refer to Figure 3 The battery 30 will be described. The battery 30 is a cylindrical battery and is a lithium-ion battery. In addition, the battery 30 is not limited to a cylindrical battery and may also be a square battery, a laminated battery, etc. Further, the battery 30 may be an aqueous battery or a non-aqueous battery. As an example of a non-aqueous battery, a lithium-ion battery can be preferably used.

[0045] The battery 30 includes an electrode body 34, an electrolyte (not shown), and an outer casing 35 that houses the electrode body 34 and the electrolyte. The electrode body 34 includes a positive electrode 31, a negative electrode 32, and a separator 33, and the electrode body 34 has a wound structure in which the positive electrode 31 and the negative electrode 32 are wound in a spiral shape with the separator 33 therebetween. The outer casing 35 has a bottomed cylindrical shape with an upper opening, and the opening of the outer casing 35 is sealed by a sealing body 36.

[0046] The battery 30 is provided with insulating plates 38a and 38b respectively disposed above and below the electrode body 34. In Figure 3 the example shown, the positive electrode lead 39 attached to the positive electrode 31 extends toward the sealing body 36 through the through hole of the insulating plate 38a, and the negative electrode lead 40 attached to the negative electrode 32 extends toward the bottom side of the outer casing 35 through the through hole of the insulating plate 38b. The positive electrode lead 39 is connected to the lower surface of the bottom plate of the sealing body 36, i.e., the internal terminal plate 41, by welding or the like. The internal terminal plate 41 is electrically connected to the top plate of the sealing body 36 and is a cover 45 that serves as an external positive electrode terminal. The negative electrode lead 40 is connected to the inner surface of the bottom of the outer casing 35 by welding or the like, and the bottom of the outer casing 35 serves as an external negative electrode terminal.

[0047] The sealing body 36 has a structure in which an internal terminal plate 41, a first valve body 42, an insulating member 43, a second valve body 44, and a cover 45 are laminated in sequence from the side of the electrode body 34. Each member constituting the sealing body 36 is, for example, in a disk shape or a ring shape, and the members other than the insulating member 43 are electrically connected to each other. The first valve body 42 and the second valve body 44 are connected to each other at their central portions and sandwich the insulating member 43 between their peripheral portions.

[0048] In the present embodiment, a safety valve 37 of the sealing body 36 is constituted by a first valve body 42, a second valve body 44, and a lid 45. When the internal pressure rises in the event of an abnormality in the battery 30, the first valve body 42 deforms and breaks in a manner that pushes the second valve body 44 toward the lid 45 side, and the current path between the first valve body 42 and the second valve body 44 is blocked. When the internal pressure further rises, the second valve body 44 breaks, and gas is discharged from the exhaust hole 45a on the side surface of the convex portion formed on the lid 45.

[0049] In addition, the arrangement position of the safety valve is not limited to the present embodiment, and the following structure may also be adopted: a safety valve is provided at the bottom of the outer casing 35 on the lower side of the battery 30, and gas is discharged from the safety valve when the internal pressure of the battery rises. In this case, it is configured such that the bottom of the outer casing 35 is exposed to the gas inflow chamber 12 (refer to Figure 2 ).

[0050] As described above, an exhaust path 16 is provided between the gas inflow chamber 12 and the exhaust portion 13 within the housing 10. In particular, in the present embodiment, the exhaust path 16 includes a coolant accumulation portion 18 at an intermediate portion in the path direction. Specifically, inside the housing 10, a coolant accumulation portion 18 is provided at an end on the exhaust portion 13 side ( Figure 2 the right side in the illustrated example) in the length direction relative to the battery accommodation chamber 11. The accumulation portion 18 is separated from the battery accommodation chamber 11 by a partition wall 82 erected from the bottom plate of the housing 10. The accumulation portion 18 is provided at a position lower than the gas inflow chamber 12 and the exhaust portion 13. Coolant 50 accumulates in the accumulation portion 18.

[0051] In the illustrated example, by forming a through hole 83 that penetrates in the thickness direction in a part of the partition wall 82, the coolant 50 in the battery accommodation chamber 11 and the coolant 50 in the accumulation portion 18 are shared. On the other hand, a structure may also be adopted in which the through hole is not formed in the partition wall 82 and the battery accommodation chamber 11 and the accumulation portion 18 are completely separated.

[0052] Moreover, an intermediate wall 84 that protrudes downward is provided at a portion on the lower surface of the top plate of the housing 10 that is located between the partition wall 82 and the first side wall 10a. Both ends in the width direction Y of the intermediate wall 84 are connected to the inner surfaces of the two second side walls 10c. As a result, the exhaust path 16 has a folding portion 86 that folds back on the lower side, which is the other side in the first direction, at an intermediate portion in the path length direction on the side of the second direction, that is, the length direction side ( Figure 2 the right side in the illustrated example) relative to the plurality of batteries 30. Therefore, the path length of the exhaust path 16 is long.

[0053] In addition, the lower end of the intermediate wall 84 is located at a position lower than the liquid level of the coolant 50. Thus, a part of the exhaust path 16 includes a coolant accumulation portion 18 of the coolant 50 provided in the folding portion 86. Therefore, when an abnormality occurs in the battery 30, the high-pressure gas flowing into the gas inflow chamber 12 from the safety valve 37 can be transported to the outlet space 88 facing the exhaust portion 13 in the housing 10 only via the coolant accumulation portion 18 of the coolant 50. At this time, the high-pressure gas discharged from the gas inflow chamber 12 toward the accumulation portion 18 side is pressed into the coolant 50 in the accumulation portion 18 by the gas pressure, becomes a bubble state in the coolant 50, and moves toward the outlet space 88.

[0054] As described above, the battery pack 1 of the present embodiment houses a plurality of batteries 30 in the housing 10, and the plurality of batteries 30 have safety valves 37 that open when the internal pressure rises. The housing 10 has a gas inflow chamber 12 into which the gas discharged from the safety valves 37 of the plurality of batteries 30 flows, an exhaust portion 13, and an exhaust path 16. In addition, the exhaust path 16 includes a coolant accumulation portion 18 of the coolant 50.

[0055] Thus, when an abnormality occurs in the battery 30, the internal pressure rises, and the high-pressure gas generated inside the battery 30 is discharged from the safety valve 37 and discharged from the gas inflow chamber 12 to the outside of the housing 10 via the exhaust path 16 from the exhaust portion 13. In Figure 2 the flow of the gas from the inside when an abnormality occurs in the middle battery 30 is indicated by arrows A1, A2, and A3. In addition, the exhaust path 16 includes a coolant accumulation portion 18 in the middle portion. Thus, the gas generated inside the battery 30 passes through the accumulation portion 18 in the housing 10, so that the gas temperature when discharged to the outside of the housing 10 can be reduced. Therefore, it is possible to prevent problems when exhausting at a high temperature in the case where the gas is flammable.

[0056] In addition, the gas inflow chamber 12 is a space provided on the upper side of the housing 10 and exposing the upper end portions of the plurality of batteries 30 and having no coolant. The exhaust path 16 includes a coolant accumulation portion 18 provided in the folding portion 86 provided on the lower side of the housing 10. Thus, the accumulation portion 18 can be provided on the exhaust path 16, and it is not necessary to make the amount of coolant accumulated in the accumulation portion 18 too large. Therefore, while suppressing the usage amount of the coolant 50, the temperature of the high-temperature gas discharged from the battery 30 can be reduced and discharged to the outside of the housing 10.

[0057] In addition, in the present embodiment, the battery accommodation chamber 11 and the gas inflow chamber 12 are partitioned by the battery holder 60, but it is not limited thereto. For example, a partition wall may be provided inside the housing 10 to partition the battery accommodation chamber 11 and the gas inflow chamber 12.

[0058] Figure 4It is a diagram corresponding to the battery pack 1a of another example of the embodiment and Figure 2 In the structure of this example, at the upper ends of one side ( Figure 4 the right side) of the coolant accumulation part on the battery 30 side and the other side ( Figure 4 the left side) of the exhaust part 13, cover wall parts 90 and 91 are respectively provided. Thus, the gas inflow chamber 12 and the outlet space 88 are separated from the coolant accumulation part 18 of the coolant 50 in such a way that they basically do not come into contact with the coolant 50.

[0059] In addition, an accumulation part inner path 92 is connected to the two cover wall parts 90 and 91, and the accumulation part inner path 92 is bent into a U shape so as to penetrate through the cover wall parts 90 and 91 at both ends. Thus, the accumulation part inner path 92 is provided in the folding part 86 of the accumulation part 18. The accumulation part inner path 92 is formed by a gas pipe. The gas pipe is made of resin, but it can also be made of a metal with relatively high heat transfer performance such as aluminum alloy. The shape of the accumulation part inner path 92 is not limited. For example, the accumulation part inner path 92 can be formed by connecting a plurality of cylindrical parts with a rectangular cross-section, or can be a shape formed by bending a pipe with a circular cross-section into a U shape. In Figure 4 it, the accumulation part inner path 92 is a shape formed by connecting three cylindrical parts extending in a straight line direction at right angles to each other, but it can also be a shape in which the middle part is smoothly bent into a substantially circular arc cross-section.

[0060] According to the structure of this example, the gas discharged from the battery 30 when the battery 30 has an abnormality flows from the gas inflow chamber 12 through the accumulation part inner path 92 toward the outlet space 88 and is discharged to the outside of the housing 10 from the exhaust part 13. At this time, when the high-temperature gas passes through the accumulation part inner path 92, heat exchange is carried out between the wall part of the gas pipe and the coolant 50 in the accumulation part 18. Therefore, the temperature of the gas passing through the accumulation part inner path 92 can be reduced, and thus the temperature of the gas discharged from the exhaust part 13 to the outside of the housing 10 can be reduced. In this example, other structures and functions are the same as those of Figures 1 - 3 the structure.

[0061] Figure 5 It is a diagram corresponding to the battery pack 1b of another example of the embodiment and Figure 2 In the structure of this example, compared with Figure 4Due to the different structures, the lower end of the path 92a inside the accumulation part reaches near the bottom plate of the housing 10. As a result, the path 92a inside the accumulation part becomes longer. The path 92a inside the accumulation part is formed by connecting a plurality of cylindrical parts with a rectangular cross-section, and baffles 94 project alternately along the path length direction from both ends in the width direction orthogonal to the path length direction. Thus, the gas path inside the path 92a inside the accumulation part is bent into a meandering shape. Therefore, the gas path for heat exchange with the coolant 50 in the accumulation part 18 becomes longer. Therefore, the temperature of the gas passing through the path 92a inside the accumulation part can be further reduced. In this example, other structures and functions are the same as those of Figures 1 - 3 the structure or Figure 4 the structure is the same.

[0062] Figure 6 The (a) of Figure 2 corresponds to the battery pack 1c which is another example of the embodiment. Figure 6 The (b) of Figure 6 is an enlarged view of part B of (a) of Figures 1 - 3 In the structure of this example, different from the structure of Figures 1 - 3 , at least the part including the gas inlet part 96 and the exhaust path 98 inside the housing 100 is filled with the coolant 50. Specifically, at the upper end part inside the housing 100, the gas inlet part 96 is provided at a position on the side opposite to the side where the exhaust part 13a is located in the length direction X with respect to the partition wall 82, and the end parts on the safety valve 37 side of the plurality of batteries 30 are exposed to the gas inlet part 96. In addition, an exhaust path 98 is provided between the gas inlet part 96 and the exhaust part 13a inside the housing 100, and the exhaust path 98 includes a bent-back part 86 that bends back in a substantially U shape at the lower side.

[0063] In this example, the entire inside of the housing 100 including the battery accommodation chamber 11, the gas inlet part 96, and the exhaust path 98 is filled with the coolant 50. Therefore, inside the housing 100, the entire exhaust path 98 from the gas inlet part 96 to the exhaust part 13a is the accumulation part of the coolant 50.

[0064] Moreover, as shown in the enlarged view of (b) of Figure 6 , the exhaust part 13a is formed by forming a thin wall part on the upper side of the first side wall 10a at one end in the length direction X of the housing 100. No holes penetrating the inside and outside of the housing 100 are formed in the side walls 10a, 10b of the housing 100.

[0065] Specifically, by forming C-shaped or circular groove portions on the side surfaces on both sides of the first side wall 10a, a C-shaped or circular thin-walled portion 101 is formed, and the exhaust portion 13a is formed by using this thin-walled portion 101. Thus, it has the following function: at the exhaust portion 13a, when an abnormality occurs in the battery 30, under the pressure of the high-pressure gas discharged from the battery 30, the thin-walled portion 101 breaks and opens. Therefore, the gas is discharged from inside the housing 100 through this opening. Thus, usually, no holes or openings are formed in the housing 100, and the coolant will not leak to the outside of the housing 100. In this way, the exhaust portion 13a can become an easily breakable portion that opens only when high-pressure gas is applied. In addition, in order to form the thin-walled portion 101, a C-shaped or circular groove portion may also be formed only on one side surface of the first side wall 10a.

[0066] According to the structure of this example as well, similar to the Figures 1 - 3 structure, the gas generated inside the battery 30 will pass through the accumulation portion of the coolant 50 inside the housing 100, so the gas temperature when the gas is discharged to the outside of the housing 100 can be reduced. In addition, in this example, the exhaust path includes a bent portion 86 that is bent into a substantially U shape, so the path length can be extended, and the time of heat exchange between the gas and the coolant when the gas is discharged to the outside of the housing can be extended, thereby improving the cooling efficiency.

[0067] In addition, in this example, there is no limitation on the up-down direction when using the battery pack 1c, and it can be used upside down relative to the Figure 6 up-down direction, or the orientation of the housing 100 can be changed by 90 degrees with the entire housing 100 along the horizontal direction relative to the Figure 6 In this example, the other structures and functions are the same as those of the Figures 1 - 3 structure.

[0068] In addition, in the above-described embodiments, it has been described that the positive terminal plate 70 for electrically connecting the positive external terminals of the plurality of batteries 30 and the negative terminal plate 80 for electrically connecting the bottom of the outer housing 35 (refer to Figure 3 ) which is the negative external terminal of the plurality of batteries 30 are provided at positions outside the upper and lower ends of the battery 30 in the up-down direction and are arranged to be opposite in the up-down direction. However, both the positive terminal plate 70 for electrically connecting the positive external terminals of the plurality of batteries 30 and the negative terminal plate 80 for electrically connecting the outer housing 35 (refer to Figure 3 ) which is the negative external terminal of the plurality of batteries 30 can also be arranged on one side in the up-down direction of the battery 30. In addition, in this case, a plate made of an insulating material can also be sandwiched between the positive terminal plate 70 for electrically connecting the positive external terminals of the plurality of batteries 30 and the outer housing 35 (refer to Figure 3Between the negative terminal plate 80 electrically connected to the bottom of ( )), thus reliably preventing a short circuit between the positive terminal plate 70 and the negative terminal plate 80. For example, in Figure 2 In the structure shown, it is also possible to invert the vertical direction of the plurality of batteries 30, provide the positive terminal plate 70 and the negative terminal plate 80 on the lower side of the plurality of batteries 30, and form an exhaust portion (safety valve) composed of a thin wall portion or the like at the bottom of the plurality of batteries 30 that becomes the upper side of the outer casing 35. At this time, the exhaust portion at the bottom of the battery 30 is exposed to the gas inflow chamber 12.

[0069] In addition, the present invention is not limited to the above-described embodiments, and various improvements and changes can be made within the scope of the matters described in the claims of the present application and their equivalents.

[0070] Explanation of reference numerals

[0071] 1, 1a, 1b, 1c, battery pack; 10, housing; 10a, 10b, first side wall; 10c, second side wall; 11, battery accommodation chamber; 12, gas inflow chamber; 13, 13a, exhaust portion; 16, exhaust path; 18, accumulation portion; 20, battery block; 30, battery; 31, positive electrode; 32, negative electrode; 33, spacer; 34, electrode body; 35, outer casing; 36, sealing body; 37, safety valve; 38a, 38b, insulating plate; 39, positive electrode lead; 40, negative electrode lead; 41, internal terminal plate; 42, first valve body; 43, insulating member; 44, second valve body; 45, cover (positive external terminal); 45a, exhaust hole; 50, coolant; 60, battery holder; 61, first holder; 62, second holder; 63, holding portion; 64, opening; 65, holding portion; 66, opening; 70, positive terminal plate; 80, negative terminal plate; 82, partition wall; 83, through hole; 84, intermediate wall; 86, folded-back portion; 88, outlet space; 90, 91, cover wall portion; 92, 92a, accumulation portion inner path; 94, baffle; 96, gas inflow portion; 98, exhaust path; 100, housing; 101, thin wall portion.

Claims

1. A battery pack, which houses a plurality of batteries in a housing, wherein, the plurality of batteries have safety valves that open by an increase in internal pressure and discharge the internal gas, and the plurality of batteries are immersed in a coolant within the housing, the housing includes: a gas inlet portion provided within the housing for the gas discharged from the battery to flow in; an exhaust portion provided in a wall portion of the housing for discharging the gas discharged from the battery to the outside of the housing; and an exhaust path provided between the gas inlet portion and the exhaust portion, including a coolant accumulation portion or an accumulation portion inner path provided within the accumulation portion.

2. The battery pack according to claim 1, wherein, the plurality of batteries are arranged along the first direction within the housing such that the safety valves are located at one end on the first direction side, the gas inlet portion is provided on the first direction side within the housing, the exhaust portion is provided on the first direction side of the wall portion at one end on the second direction orthogonal to the first direction, the exhaust path has a folding portion that folds back on the other side in the first direction at an intermediate portion in the path length direction on the side in the second direction relative to the plurality of batteries.

3. The battery pack according to claim 2, wherein, the first direction side is the upper side during use, and the other side in the first direction is the lower side during use, the gas inlet portion is a space that exposes the end portion on the safety valve side of the plurality of batteries and does not have the coolant, the exhaust path includes the accumulation portion or the accumulation portion inner path provided in the folding portion.

4. The battery pack according to claim 1, wherein, at least a portion of the housing including the gas inlet portion and the exhaust path is filled with the coolant.

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