JP2019079605A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of suppressing a decrease in liquid stored in a container. A battery pack (1) includes a battery cell (21), a container (10M), and a sheet (41). The container has an internal space (10sp) for accommodating the battery cell and a first vent hole (10ha) for communicating the internal space with the external space (60), so that at least a part of the battery cell is immersed. A volatile liquid (31) is stored. The sheet has elasticity and airtightness, is provided closer to the first ventilation port side than the battery cell, and has an internal space having a first space (10sa) on the battery cell side and a second space (10sb) on the first ventilation port side. ) And the first space is airtightly closed. [Selection diagram] Figure 1

Description

  The present invention relates to a battery pack.

  In vehicles such as an electric vehicle (EV), a hybrid vehicle (HEV), and a plug-in hybrid vehicle (PHEV), a battery pack is mounted as a power supply for supplying electric power for driving a motor as a drive source. A plurality of battery cells are accommodated in the battery pack, and the plurality of battery cells are electrically connected to one another in series or in parallel. The temperature of the battery cell changes during charging and discharging, and the temperature rises according to the traveling time of the vehicle. The usable temperature is determined for each battery cell, and a vehicle battery pack may be provided with a cooling function for the purpose of suppressing exceeding the usable temperature.

  Patent Document 1 discloses a technique for immersing and cooling a battery in a liquid in a container.

JP 2014-49424 A

  By the way, when the liquid which cools the battery cell in a battery pack is a volatile liquid, the liquid in a battery pack may decrease because the vaporized liquid is discharge | released out of a battery pack.

  An object of the present invention is to provide a battery pack capable of suppressing the reduction of liquid stored in a container.

  The battery pack of the present invention includes a battery cell, a container, and a sheet. The container has an internal space for accommodating the battery cell, and a first vent communicating the internal space with the external space, and is a liquid having volatility so that at least a part of the battery cell is immersed. Are stored. The sheet is stretchable and airtight, and is provided closer to the first vent than the battery cell, and the internal space is a first space on the battery cell side and a second on the first vent side. The first space is airtightly closed, separated from the space.

  In the battery pack of the present invention, the stretchable and airtight sheet tightly closes the first space. Since the sheet airtightly closes the first space, even if the liquid stored in the first space is vaporized, the vaporized liquid is prevented from flowing out. That is, according to the battery pack of the present invention, it is possible to suppress the reduction of the liquid in the battery pack.

FIG. 1 is a cross-sectional view showing a battery pack according to the embodiment. FIG. 2 is a cross-sectional view showing the battery pack according to the embodiment. FIG. 3 is a cross-sectional view showing the battery pack according to the embodiment. FIG. 4 is a cross-sectional view showing a battery pack according to a first modification of the embodiment. FIG. 5 is a cross-sectional view showing a battery pack according to a second modification of the embodiment.

  Hereinafter, a battery pack according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily conceived by those skilled in the art or those that are substantially the same.

[Embodiment]
Embodiments will be described with reference to FIGS. 1 to 3. Embodiments relate to a battery pack. FIG. 1 is a cross-sectional view showing a battery pack according to the embodiment. FIG. 2 is a cross-sectional view showing the battery pack according to the embodiment. FIG. 3 is a cross-sectional view showing the battery pack according to the embodiment. FIG. 2 and FIG. 3 are cross-sectional views showing an example of use of the battery pack according to the embodiment.

  The battery pack 1 according to the embodiment is, for example, a vehicle battery pack mounted on a vehicle (for example, an electric vehicle or a hybrid vehicle) including a motor as a drive source. The battery pack 1 is used to supply power to the motor and the like.

  In the following description, among the first direction, second direction, and third direction orthogonal to one another, the first direction is referred to as "depth direction", the second direction is referred to as "width direction", and the third direction is referred to. Is referred to as "height direction". Also, typically, in the state where battery pack 1 is mounted on a vehicle, the depth direction and the width direction are directions along the horizontal direction, and the height direction corresponds to the direction along the vertical direction . Furthermore, in the height direction, the upper side in the vertical direction is referred to as “upper side”, and the lower side in the vertical direction is referred to as “lower side”. Moreover, each direction used by the following description is demonstrated as a direction in the state with which the battery pack 1 was mounted in the vehicle, unless there is particular notice.

  As shown in FIG. 1, the battery pack 1 according to the embodiment includes a container 10 </ b> M, a battery cell 21, and a sheet 41. The container 10M has an internal space 10sp. The shape of the container 10M is a substantially rectangular parallelepiped. The container 10M accommodates the battery cell 21 in the internal space 10sp. In the embodiment, the container 10M is a housing 10. The housing 10 is a box-shaped member having thermal conductivity. The housing 10 is made of, for example, iron (Fe), copper (Cu), aluminum (Al) or the like. The shape of the container 10M is not limited to a substantially rectangular shape. For example, the shape of the container 10M may be a cylindrical shape having an internal space 10sp.

  In the embodiment, the housing 10 includes a first portion 10a and a second portion 10b. The first portion 10a has a box-like shape whose upper side is open, and the second portion 10b has a box-like shape whose lower side is open. The housing 10 is formed by connecting the first portion 10 a and the second portion 10 b such that the opening of the first portion 10 a and the opening of the second portion 10 b are aligned. That is, the first portion 10a is disposed below the second portion 10b.

  The housing 10 has a vent 10ha (first vent 10ha) for communicating the internal space 10sp with the external space 60. In the embodiment, the upper wall of the second portion 10b has a vent 10ha. The communicating pipe 11 is connected to the vent 10ha. The communication tube 11 is a substantially cylindrical member. The internal space 10 sp is in communication with the external space 60 via the vent 10 ha and the communication pipe 11. Here, the external space 60 is, for example, the atmosphere. For example, when the battery pack 1 is housed in a case, the external space 60 corresponds to a space between the battery pack 1 and the case.

  The sheet 41 is at least partially provided in the internal space 10sp. The sheet 41 is airtight and stretchable. The sheet 41 is provided closer to the vent 10 ha than the battery cell 21. The sheet 41 airtightly closes the first space 10sa by separating the internal space 10sp into a first space 10sa on the battery cell 21 side and a second space 10sb on the air vent 10ha side. In the embodiment, the first space 10sa is located below the second space 10sb.

  The first portion 10a has a first peripheral surface 10ae located on the upper side of the wall of the first portion 10a surrounding the opening of the first portion 10a. The second portion 10b has a second peripheral surface 10be located below the wall of the second portion 10b surrounding the opening of the second portion 10b. In the embodiment, the outer peripheral end of the sheet 41 is sandwiched between the first peripheral surface 10 ae and the second peripheral surface 10 be. The outer peripheral end of the sheet 41 is sandwiched between the region on the inner peripheral side of the first peripheral surface 10 ae and the region on the inner peripheral side of the second peripheral surface 10 be. Moreover, the area | region of the outer peripheral side of 1st peripheral surface 10ae and the area | region of the outer peripheral side of 2nd peripheral surface 10be are in contact. Note that at least one of the first peripheral surface 10ae and the second peripheral surface 10be may have a step between the region on the inner peripheral side and the region on the outer peripheral side. This level | step difference is formed so that the clearance gap which clamps and hold | maintains the sheet | seat 41 between the area | region of the inner peripheral side of 1st peripheral surface 10ae, and the area | region of the inner peripheral side of 2nd peripheral surface 10be may be made.

  The first space 10sa is a space surrounded by the first portion 10a and the sheet 41 in the internal space 10sp. The second space 10sb is a space surrounded by the second portion 10b and the sheet 41 in the internal space 10sp. For example, when the temperature of the battery pack 1 is a temperature below normal temperature (in this specification, 20 degrees Celsius), the sheet 41 is provided to be substantially horizontal to a plane orthogonal to the height direction It is done. In addition, for example, when the temperature of the battery pack 1 is a temperature equal to or lower than the normal temperature, the sheet 41 may hang downward. For example, a part of the sheet 41 may be in contact with the upper surface of the battery cell 21.

  The battery cell 21 is provided in the first space 10sa. The battery cell 21 is a chargeable / dischargeable secondary battery. The battery cell 21 of the embodiment is a cylindrical lithium ion battery. In the embodiment, a plurality of battery cells 21 are provided in the first space 10sa. The plurality of battery cells 21 are connected in series or in parallel to one another to constitute a battery module BM. The plurality of battery cells 21 are arranged in a matrix in the depth direction and the width direction. A fixed gap is provided between the plurality of battery cells 21.

  The liquid 31 is stored in the first space 10sa of the housing 10 so that at least a part of the battery cell 21 is immersed. The liquid 31 becomes a refrigerant of the battery pack 1 when the temperature of the battery cell 21 rises. In the embodiment, the liquid 31 is also filled in the gaps between the plurality of battery cells 21 and is in contact with the plurality of battery cells 21. The liquid 31 is stored so that about half of the lower side of the battery cell 21 is immersed. The battery cell 21 may be entirely immersed in the liquid 31. In addition, when the battery cell 21 is housed in a case or the like having thermal conductivity, the battery cell 21 may not be in contact with the liquid 31. In this case, the battery cell 21 exchanges heat with the liquid 31 via a case or the like having thermal conductivity.

  The liquid 31 has volatility. The liquid 31 has a boiling point in the range of, for example, 50 degrees Celsius or more and 260 degrees Celsius or less. The liquid 31 may be solid, for example, when the battery pack 1 is at a temperature lower than the normal use temperature (for example, 30 degrees Celsius) of the battery cell 21. The thermal conductivity of the liquid 31 at the normal use temperature (for example, 30 degrees Celsius) of the battery cell 21 is higher than the thermal conductivity of air. Here, the normal use temperature is a temperature range in which the battery cell 21 can be used while suppressing the influence of the temperature on the battery output and battery life of the battery cell 21. The normal use temperature of the lithium ion battery is, for example, a temperature range of 30 degrees Celsius to 50 degrees Celsius.

  As the liquid 31, for example, an organic solvent such as a fluorine-based inert liquid or paraffin, pure water or the like can be used. Use a liquid containing PFPE (perfluoropolyether: perfluoropolyether), PFC (perfluorocarbon: perfluorocarbon), hydrofluoropolyether (HFPE: hydrofluoropolyether), HFE (hydrofluoroether: hydrofluoroether), etc. as a fluorine-based inert liquid Can. Further, an antifreeze liquid can also be used as the liquid 31. For example, as the antifreeze liquid, a liquid containing ethanol or ethylene glycol can be used. Further, a rust preventing material may be added to the liquid 31.

  The sheet 41 is formed using a material selected in consideration of air tightness, elasticity, durability and chemical resistance. For example, as the sheet 41, a sheet such as a fluorine rubber sheet, a silicone rubber sheet, a nitrile rubber sheet, a PTFE (polytetrafluoroethylene) rubber sheet, a urethane rubber sheet, or a natural rubber sheet can be used.

  Hereinafter, with reference to FIG. 2 and FIG. 3, an example of the use condition of the battery pack 1 which concerns on embodiment is demonstrated. When the temperature of the battery cell 21 rises, the liquid 31 receives the amount of heat from the battery cell 21, thereby suppressing the temperature rise of the battery cell 21. At this time, the liquid 31 which has received the heat from the battery cell 21 transmits a part of the heat to the casing 10 (the container 10M). In addition, a part of the liquid 31 which has received the heat from the battery cell 21 is vaporized.

  Since the first space 10sa is airtightly closed by the sheet 41, the outflow of the vaporized liquid 31 to the outside (the external space 60, the first space 10sa, and the like) is suppressed. Therefore, the vaporized liquid 31 remains in the first space 10sa. When the liquid 31 is vaporized, the pressure in the first space 10 sa is higher than the pressure in the outer space 60.

  When the pressure of the first space 10sa is increased by the vaporization of part of the liquid 31, as shown in FIG. 2, the sheet 41 extends toward the second space 10sb by the pressure P1 of the first space 10sa. Here, the second space 10sb has a width that allows the sheet 41 to stretch. For example, in the second space 10sb, when the temperature of the battery cell 21 is lower than the upper limit of the normal use temperature of the battery cell 21, the sheet 41 is not in contact with the upper wall portion of the housing 10 (second portion 10b) The breadth of

  As the sheet 41 extends toward the second space 10sb, the first space 10sa is enlarged, and the pressure in the first space 10sa is maintained below a certain pressure. At this time, as indicated by an arrow P2 in FIG. 2, part of the gas in the second space 10sb is discharged to the external space 60 through the vent 10ha and the communication pipe 11. By partially discharging the gas in the second space 10sb to the external space 60, the pressure in the housing 10 (the container 10M) is maintained at a predetermined pressure or less. For example, the pressure in the housing 10 (the container 10M) is equal to or lower than the pressure of the first space 10sa (hereinafter referred to as the allowable upper limit pressure) when the temperature of the liquid 31 is the upper limit temperature of the normal use temperature of the battery cell 21. Will be kept. Here, the allowable upper limit pressure is, for example, a pressure when the liquid 31 in the upper limit temperature of the normal use temperature of the battery cell 21 and the gas in the first space 10 sa are in a gas-liquid equilibrium state. That is, the allowable upper limit pressure is the sum of the vapor pressure of the liquid 31 at the upper limit temperature of the normal use temperature of the battery cell 21 and the atmospheric pressure.

  As shown in FIG. 3, when the difference between the pressure of the first space 10sa and the pressure of the second space 10sb exceeds a predetermined first value, the sheet 41 is torn. For example, the first value is a difference between a predetermined pressure which is equal to or higher than the allowable upper limit pressure and less than the maximum endurance pressure of the battery pack 1 and the atmospheric pressure. The first space 10sa is connected to the second space 10sb via the hole 41h made by the sheet 41 being torn. As shown by arrow P3 and arrow P4 in FIG. 3, the gas in the first space 10sa is connected to the second space 10sb, the vent 10ha, and the communication tube 11 by connecting the first space 10sa and the second space 10sb. It flows out to the external space 60 via By the gas of the first space 10sa flowing out to the external space 60, the pressure of the first space 10sa is maintained at a certain level or less.

  For example, the pressure of the first space 10sa is kept below the allowable upper limit pressure. In this case, the sheet 41 functions as a safety device for releasing the pressure in the first space 10sa when the pressure in the first space 10sa rises above a certain level. The tearability of the sheet 41 can be adjusted to be the desired tearability by, for example, the thickness of the sheet 41 and the selection of the material.

  In addition, it can be estimated based on information, such as a temperature monitoring apparatus of the battery cell 21, a voltage monitoring apparatus, etc. whether the sheet | seat 41 was torn, for example. For example, when the temperature monitoring device detects a temperature above a certain level, an alert may be provided on the mounted vehicle to recommend inspection of the seat 41.

  The case 10 may be provided with a relief valve 52. The relief valve 52 is disposed at a position between the liquid 31 and the sheet 41. The relief valve 52 in the normal state is in the closed state, and the first space 10 sa is kept airtight. The relief valve 52 changes from the closed state to the open state when the difference between the pressure in the first space 10sa and the pressure in the external space 60 of the housing 10 (container 10M) becomes larger than a predetermined second value. Become. For example, the second value is a difference between a predetermined pressure which is equal to or higher than the allowable upper limit pressure and less than the maximum endurance pressure of the battery pack 1 and the atmospheric pressure. The second value is set to a value larger than the first value. When the relief valve 52 changes from the closed state to the open state, the relief valve 52 releases part of the gas in the first space 10sa to the external space 60 to maintain the pressure in the first space 10sa at a pressure less than or equal to a certain level. . For example, the relief valve 52 keeps the pressure of the first space 10sa such that the difference between the pressure of the first space 10sa and the pressure of the external space 60 is equal to or less than a second value.

  In the battery pack 1, the relief valve 52 may be omitted.

  The means for suppressing an excessive pressure rise in the first space 10sa may not be the sheet 41. In this case, a relief valve 52 is provided at a position between the liquid 31 and the sheet 41. The relief valve 52 is switched from the closed state to the open state when the difference between the pressure in the first space 10sa and the pressure in the external space 60 of the housing 10 (container 10M) becomes larger than a predetermined first value. , The pressure of the first space 10sa is maintained at a pressure not more than a predetermined level.

  As shown in FIGS. 1 to 3, the housing 10 is provided with a connector 51. The connector 51 is disposed at a position between the liquid 31 and the sheet 41. The battery cell 21 (battery module BM) is electrically connected to an electrical component 71 outside the battery pack 1 via the connector 51. In the embodiment, the connector 51 electrically connects the connecting member 61 such as a bus bar electrically connected to the battery cell 21 (battery module BM) and the electric wire 62 electrically connected to the electrical component 71. Do. The connector 51 is a waterproof connector. The connector 51 is provided in the housing 10 such that the airtight state of the first space 10sa is maintained. That is, the connector 51 is provided such that no gap is formed between the connector 51 and the housing 10. For example, the connector 51 and the housing 10 may be sealed by a water blocking member or the like. Moreover, in order to prevent a short circuit, the connection member 61 is preferably coated with a resin or the like.

  As described above, the battery pack 1 according to the embodiment includes the battery cell 21, the container 10 </ b> M, and the sheet 41 as described above. The container 10M has an internal space 10sp for accommodating the battery cell 21 and a vent 10ha communicating the internal space 10sp with the external space 60, and has volatility so that at least a part of the battery cell 21 is immersed. The liquid 31 is stored. The sheet 41 has elasticity and airtightness, and is provided closer to the vent 10ha than the battery cell 21, and the internal space 10sp is formed by a first space 10sa on the battery cell 21 side and a second space 10sb on the vent 10ha side. And tightly close the first space 10sa.

  The liquid 31 receives heat from the battery cell 21 when the temperature of the battery cell 21 rises, thereby suppressing the temperature rise of the battery cell 21. At least a portion of the liquid 31 is vaporized by receiving heat from the battery cell 21. In the battery pack 1 of the embodiment, since the first space 10 sa is airtightly closed by the sheet 41, the vaporized liquid 31 in the first space 10 sa is prevented from flowing out to the external space 60. By suppressing the outflow of the vaporized liquid 31 to the external space 60, the reduction of the liquid 31 in the battery pack 1 can be suppressed. Further, even when the temperature of the battery pack 1 is normal temperature, the amount of vapor is kept constant (for example, the amount of saturated vapor) in the hermetically sealed first space 10sa, and the vaporization of the liquid 31 does not proceed more than a certain amount. The reduction of the liquid 31 in the container 10M is suppressed.

  Further, the battery pack 1 according to the embodiment may further include a relief valve 52 attached to the container 10M. The relief valve 52 is located between the seat 41 and the liquid 31, and is opened from the closed state when the difference between the pressure in the first space 10sa and the pressure in the external space 60 exceeds a predetermined first value. Thus, the first space 10sa and the external space 60 are communicated with each other. By providing the relief valve 52, the pressure of the first space 10sa can be maintained at a certain pressure or less.

  Further, the sheet 41 in the embodiment may be a sheet that breaks when the difference between the pressure of the first space 10sa and the pressure of the second space 10sb exceeds a predetermined first value. By breaking the sheet 41, it is possible to suppress an increase in pressure in the first space 10sa.

  Furthermore, the battery pack 1 according to the embodiment is attached to the container 10M in addition to the sheet 41 that breaks when the difference between the pressure in the first space 10sa and the pressure in the second space 10sb exceeds a predetermined first value. A relief valve 52 may be included. The relief valve 52 is located between the seat 41 and the liquid 31, and changes from the closed state to the open state when the difference between the pressure in the first space 10sa and the pressure in the external space 60 exceeds a predetermined second value. As a result, the first space 10sa and the external space 60 are communicated with each other. Here, the second value is larger than the first value. For example, when the pressure in the first space 10sa continues to rise even after the sheet 41 is torn, the pressure in the first space 10sa can be maintained at a certain level or less by opening the relief valve 52.

  The size of the second space 10sb is determined in consideration of the elasticity of the sheet 41, the amount of the liquid 31, and the size of the housing 10 (the container 10M). In addition, a filter or the like that suppresses the infiltration of water or the like into the battery pack 1 may be provided between the second space 10 sb and the external space 60.

First Modification of Embodiment
A first modified example of the embodiment will be described with reference to FIG. The first modification of the embodiment relates to a battery pack. FIG. 4 is a cross-sectional view showing a battery pack according to a first modification of the embodiment.

  The battery pack 1 of this modification is different from the battery pack 1 according to the above embodiment in that, for example, the container 10M includes a first housing 10, a communication pipe 11, and a second housing 12.

  The first housing 10 of this modification has a substantially rectangular parallelepiped shape. As shown in FIG. 4, the first housing 10 accommodates the battery cell 21 in the internal space 10 sp. A plurality of battery cells 21 are accommodated in the internal space 10 sp of the first housing 10. In the internal space 10 sp of the first housing 10, a battery module BM is configured by the plurality of battery cells 21.

  The liquid 31 is stored in the internal space 10 sp of the first housing 10 so that at least a part of the battery cell 21 (battery module BM) is immersed. The liquid 31 has volatility. For example, the liquid 31 has a boiling point in the range of not less than 50 degrees Celsius and less than 260 degrees Celsius. The liquid 31 becomes a refrigerant of the battery pack 1 when the temperature of the battery cell 21 rises.

  As in the above-described embodiment, as the liquid 31, for example, a fluorine-based inert liquid, an organic solvent such as acetone or paraffin, pure water, or the like can be used. For example, a liquid containing PFPE (perfluoropolyether), PFC (perfluorocarbon: perfluorocarbon), hydrofluoropolyether (HFPE: hydrofluoropolyether), HFE (hydrofluoroether: hydrofluoroether), etc. as a fluorine-based inert liquid It can be used. Further, an antifreeze liquid can also be used as the liquid 31. As the antifreeze liquid, a liquid containing ethanol or ethylene glycol can be used. Further, a rust preventing material may be added to the liquid 31.

  The first housing 10 has a second vent 10 hb. The second vent 10 hb is located above the liquid 31. One end of the communication tube 11 is connected to the second vent 10 hb.

  The second housing 12 is provided on the upper side of the first housing 10. The second housing 12 has a first vent 10 ha and a third vent 10 hc. The first vent 10 ha communicates the internal space 10 sp of the second housing 12 with the external space 60.

  In the battery pack 1 according to the present modification, the communication pipe 13 is provided, and the communication pipe 13 is connected to the first vent 10 ha. The internal space 10 sp of the second housing 12 communicates with the external space 60 via the first vent 10 ha and the communication pipe 13. The other end of the communication pipe 11 whose one end is connected to the second vent 10 hb is connected to the third vent 10 hc. The internal space 10sp of the first housing 10 and the internal space 10sp of the second housing 12 communicate with each other via the second vent 10hb, the communication pipe 11, and the third vent 10hc.

  In the present variation, the second housing 12 includes a first portion 12a and a second portion 12b. The first portion 12a has a box-like shape whose upper side is open, and the second portion 12b has a box-like shape whose lower side is open. The second housing 12 is formed by connecting the first portion 12a and the second portion 12b such that the opening of the first portion 12a and the opening of the second portion 12b are aligned when seen from the height direction. Ru. Here, the second portion 12 b is disposed on the upper side of the first portion 12 a. In addition, the first portion 12a has a third vent 10hc, and the second portion 12b has a first vent 10ha. The inner wall surface of the second portion 12 b is in the shape of a bowl that is recessed downward. The third vent 10 hc is disposed at a position corresponding to the bottom of the bowl-shaped inner wall surface. That is, the third vent 10 hc is an opening that is open at the lowermost portion of the second housing 12.

  At least a portion of the sheet 41 is provided in the internal space 10 sp of the second housing 12. The sheet 41 is disposed between the first vent 10 ha and the third vent 10 hc in the second housing 12. The sheet 41 is airtight and stretchable. The sheet 41 separates the internal space 10 sp into a first space 10 sa on the battery cell 21 side and a second space 10 sb on the first vent 10 ha side. The sheet 41 airtightly closes the first space 10sa. In the present variation, the first space 10sa is located below the second space 10sb. Here, the second space 10sb has a width that allows the sheet 41 to stretch. For example, in the second space 10sb, when the temperature of the battery cell 21 is lower than the upper limit temperature of the normal use temperature of the battery cell 21, the sheet 41 is on the upper wall of the second housing 12 (second portion 12b). It is wide enough not to touch.

  The first portion 12a has a first peripheral surface 12ae located on the upper side of the wall portion of the first portion 12a surrounding the opening of the first portion 12a. The second portion 12b has a second peripheral surface 12be located below the wall of the second portion 12b surrounding the opening of the second portion 12b. In the present modification, the outer peripheral end of the sheet 41 is sandwiched between the first peripheral surface 12 ae and the second peripheral surface 12 be. Moreover, the area | region of the outer peripheral side of 1st peripheral surface 12ae and the area | region of the outer peripheral side of 2nd peripheral surface 12be are in contact. Note that at least one of the first peripheral surface 12ae and the second peripheral surface 12be may have a step between the region on the inner peripheral side and the region on the outer peripheral side. The step is formed such that there is a gap for sandwiching and holding the sheet 41 between the region on the inner peripheral side of the first peripheral surface 12ae and the region on the inner peripheral side of the second peripheral surface 12be.

  The first space 10sa is a space surrounded by the first portion 10a and the sheet 41 in the internal space 10sp. The second space 10sb is a space surrounded by the second portion 10b, the communication pipe 11, the first housing 10, and the sheet 41 in the internal space 10sp. For example, when the temperature of the battery pack 1 is a temperature equal to or lower than normal temperature, the sheet 41 is provided to be substantially horizontal to a plane orthogonal to the height direction. In addition, for example, when the temperature of the battery pack 1 is a temperature equal to or lower than the normal temperature, the sheet 41 may hang downward. For example, a part of the sheet 41 may be in contact with the upper surface of the battery cell 21.

  Similar to the above-described embodiment, the sheet 41 is formed using a material selected in consideration of air tightness, stretchability, durability, and chemical resistance. For example, as the sheet 41, a sheet such as a fluorine rubber sheet, a silicone rubber sheet, a nitrile rubber sheet, a PTFE (polytetrafluoroethylene) rubber sheet, a urethane rubber sheet, or a natural rubber sheet can be used.

  In the case of this modification, the third vent 10 hc is disposed at a position corresponding to the bottom of the bowl-shaped inner wall surface. For example, when the vaporized liquid 31 cools and liquefies in the first space 10sa of the second portion 12b, the liquid 31 can move along the inner wall surface and smoothly return into the first housing 10.

  A relief valve 52 is provided at a position between the sheet 41 and the liquid 31 in the container 10M. In the present modification, the relief valve 52 is provided on the first space 10 sa side of the first housing 10 and / or the second housing 12. If the seat 41 is torn when the pressure in the first space 10sa becomes equal to or higher than a predetermined pressure (for example, the allowable upper limit pressure), the relief valve 52 may be omitted.

  A connector 51 is provided at a position between the liquid 31 and the second vent 10 hb in the first housing 10. The connector 51 electrically connects the battery cell 21 (battery module BM) and the electric component 71 outside the battery pack 1. In the present modification, connector 51 electrically connects connecting member 61 such as a bus bar electrically connected to battery cell 21 (battery module BM) and electric wire 62 electrically connected to electric component 71. Connecting. The connection member 61 is preferably coated with a resin or the like in order to prevent a short circuit.

  As described above, in the battery pack 1 according to the first modified example, the container 10M includes the first housing 10, the communication pipe 11, and the second housing 12. The first housing 10 accommodates the battery cell 21, stores the liquid 31, and has a second vent 10 hb above the liquid 31. The communicating pipe 11 is connected to the second vent 10 hb. The second housing 12 has a first vent 10ha and a third vent 10hc communicating with the second vent 10hb via the communication pipe 11. The sheet 41 is disposed at a position between the first vent 10 ha and the third vent 10 hc in the second housing 12.

  A battery pack 1 according to a first modification includes a first case 10 accommodating a battery cell 21 and storing a liquid 31, and a second case 12 in which a sheet 41 is provided in an internal space 10sp. There is. By providing the sheet 41 in the second housing 12 different from the first housing 10, the battery pack 1 can be disposed in accordance with the size and shape of the mounting space of the battery pack 1. That is, in the first housing 10, the sheet 41 is not provided inside, and the space corresponding to the second space 10sb is also reduced. Therefore, the first housing 10 that accommodates the battery cell 21 (battery module BM) can be smaller than the housing 10 (container 10M) of the above-described embodiment. For example, when the mounting space of the battery pack in the vehicle is not large enough to mount the battery pack 1 according to the above-described embodiment, the mounting space of the first casing 10 of the battery pack 1 according to the first modification And the second housing 12 can be arranged in another space.

  A tube other than the communication tube 11 may be connected between the first housing 10 and the second housing 12. In addition, a filter such as the communication pipe 11 connecting the first housing 10 and the second housing 12 may be provided.

Second Modification of Embodiment
A second modified example of the embodiment will be described with reference to FIG. The second modification of the embodiment relates to a battery pack. FIG. 5 is a cross-sectional view showing a battery pack according to a second modification of the embodiment.

  The battery pack 1 of the present modification is different from the battery pack 1 according to the above embodiment in that, for example, a needle portion 81 is provided in a housing 10 (container 10M).

  As shown in FIG. 5, the needle portion 81 is disposed in the second space 10 sb and protrudes toward the sheet 41 from the inner wall surface 10 uw of the housing 10 facing the sheet 41. In the present modified example, the needle portion 81 is provided on the upper inner wall surface 10 uw of the housing 10 (second portion 10 b). The tip of the needle portion 81 on the sheet 41 side is pointed at an acute angle. The length from the base end side to the tip end side of the needle portion 81 is set so that the tip end of the needle portion 81 penetrates the sheet 41 when the sheet 41 reaches a predetermined height position. Here, the predetermined height position is the height position of the sheet 41 when the difference between the pressure in the first space 10sa and the pressure in the second space 10sb reaches the above-described first value. When the difference between the pressure in the first space 10sa and the pressure in the second space 10sb exceeds the above-described first value, the tip of the needle portion 81 penetrates the sheet 41 and breaks the sheet 41. That is, the sheet 41 bulges toward the needle portion 81 as the pressure in the first space 10sa increases. Then, when the difference between the pressure of the first space 10sa and the pressure of the second space 10sb exceeds the above-described first value, the needle portion 81 penetrates the sheet 41 and breaks the sheet 41. Although the present modification has been described using an example in which one needle portion 81 is provided, a plurality of needle portions 81 may be provided on the inner wall surface 10 uw.

  As described above, the battery pack 1 according to the second modification is disposed in the second space 10sb and protrudes toward the sheet 41 from the inner wall surface 10uw of the housing 10 (container 10M) facing the sheet 41. The needle portion 81 is further included.

  The needle portion 81 penetrates the sheet 41 and breaks the sheet 41 when the difference between the pressure of the first space 10sa and the pressure of the second space 10sb exceeds a predetermined first value. Even when the sheet 41 is not torn spontaneously by providing the needle portion 81, the sheet when the difference between the pressure of the first space 10sa and the pressure of the second space 10sb exceeds the first value described above. You can break 41.

  The contents disclosed in the above-described embodiment and each modification can be implemented in combination as appropriate.

DESCRIPTION OF SYMBOLS 1 battery pack 10 housing | casing, 1st housing | casing 10a, 12a 1st part 10b, 12b 2nd part 10ha vent, 1st vent 10hb 2nd vent 10hc 3rd vent 10M container 10sa 1st space 10sb 2nd Space 10 sp Internal space 11, 13 Communication pipe 12 Second casing 21 Battery cell 31 Liquid 41 Sheet 41 h Hole 51 Connector 52 Relief valve 60 External space 61 Connection member 62 Electric wire 71 Electrical component 81 Needle part P1 Pressure P2 to P4 Arrow

Claims (5)

Battery cell,
An internal space for accommodating the battery cell, and a first vent communicating the internal space with the external space, and a volatile liquid is stored so that at least a portion of the battery cell is immersed. A container,
It has stretchability and airtightness, and is provided closer to the first vent than the battery cell, and the internal space is separated into a first space on the battery cell side and a second space on the first vent side. A seat that airtightly closes the first space;
A battery pack comprising: The container includes a first housing, a communication pipe, and a second housing,
The first housing accommodates the battery cell, stores the liquid, and has a second vent above the liquid.
The communication tube is connected to the second vent.
The second housing has the first vent and a third vent communicating with the second vent through the communication pipe.
The battery pack according to claim 1, wherein the sheet is disposed between the first vent and the third vent in the second housing.   The battery pack according to claim 1 or 2, wherein the sheet is broken when a difference between the pressure in the first space and the pressure in the second space exceeds a predetermined first value. Further comprising a relief valve attached to the container;
The relief valve is located between the seat and the liquid, and is opened from the closed state when the difference between the pressure in the first space and the pressure in the external space exceeds a predetermined second value. To communicate the first space with the external space,
The battery pack according to claim 3, wherein the second value is larger than the first value. Further comprising a relief valve attached to the container;
The relief valve is located between the seat and the liquid, and is opened from the closed state when the difference between the pressure in the first space and the pressure in the external space exceeds a predetermined first value. The battery pack according to claim 1, wherein the first space and the external space are communicated with each other.

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