Vehicle battery pack

Abstract

This vehicle battery pack which is provided to a vehicle comprises: a battery module including a plurality of battery cells and partition parts that are disposed between the plurality of battery cells in the arrangement direction of the plurality of battery cells, that have a thermal insulation material thereinside, and that are filled with a cooling medium; vaporized gas discharge valves which operate in response to a pressure increase associated with vaporization of the cooling medium in the partition parts, and through which a vaporized gas generated by the vaporization is discharged from the partition parts; a coupling duct which couples the plurality of vaporized gas discharge valves; and a detection sensor which detects discharge of the vaporized gas at the vaporized gas discharge valves.

Description

Vehicle battery packs

[0001] The present invention relates to the technical field of battery packs mounted on vehicles.

[0002] For example, hybrid vehicles, electric vehicles, and other electric vehicles that are configured to drive the wheels using the power of an electric motor are equipped with a battery (secondary battery) to supply power to the electric motor. Generally, the discharge characteristics of a battery change depending on the temperature, and when the battery temperature is high, the battery needs to be cooled.

[0003] When cooling a battery, it is preferable to configure the battery so that heat can be easily transferred between the battery cells. This allows heat to be transferred to the surrounding battery cells and the cooling medium when a battery cell becomes locally hot, thereby cooling that battery cell.

[0004] Such battery packs are known to be configured to facilitate heat transfer between battery cells under normal conditions, but to make it difficult for heat to transfer between battery cells in the event of thermal runaway of the battery pack (see Patent Document 1 below).

[0005] International Publication No. 2018 / 169044

[0006] It is important to detect the occurrence of thermal runaway in battery cells. By detecting thermal runaway appropriately and early, it becomes possible to move the vehicle to a safe place and evacuate the occupants quickly.

[0007] Therefore, the present invention has been made in consideration of these problems, and aims to propose a vehicle battery pack that has a configuration that can detect thermal runaway while taking into account both the cooling efficiency and insulation of the battery cells.

[0008] The vehicle battery pack according to the present invention includes a battery module having a plurality of battery cells, a partition section disposed between the plurality of battery cells in the arrangement direction of the battery cells, an insulating material disposed therein, and the partition section being filled with a cooling solvent, a vaporized gas release valve that is activated by a pressure increase caused by the evaporation of the cooling solvent within the partition section and releases the vaporized gas resulting from the evaporation from the partition section, a connecting duct connecting the plurality of vaporized gas release valves, and a detection sensor that detects the release of the vaporized gas from the vaporized gas release valve. This allows efficient heat transfer between two adjacent battery cells via the partition section while the cooling solvent is present in liquid form within the partition section. When thermal runaway occurs in a battery cell, the temperature rise of the battery cell causes the cooling solvent to vaporize and be released to the outside through the partition section, thereby placing the two battery cells adjacent to each other via the insulating material and the vaporized gas, significantly reducing thermal conductivity between the battery cells. Furthermore, the generation of vaporized gas resulting from the evaporation of the cooling solvent can be detected by measuring the pressure in the connecting duct using a detection sensor such as a pressure sensor.

[0009] According to the present invention, it is possible to propose a vehicle battery pack having a configuration that can detect thermal runaway while taking into consideration both the cooling efficiency and thermal insulation of the battery cells.

[0010] Fig. 1 is a schematic cross-sectional view showing an example of the configuration of a vehicle battery pack according to an embodiment of the present invention; Fig. 2 is a perspective view showing a cross section of a part of a partition; Fig. 3 is a cross-sectional view of a partition; Fig. 4 is a perspective view showing a part of a vehicle battery pack; Fig. 5 is a diagram for explaining a discharge path when a cooling solvent is vaporized; Fig. 6 is a flowchart of a process executed by a control unit to detect the occurrence of thermal runaway; Fig. 7 is an explanatory diagram of an example of the configuration of a modified vehicle battery pack;

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle battery pack 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings. 1. Configuration of the vehicle battery pack

[0012] An example of the configuration of a vehicle battery pack 1 of the present invention is shown in Figure 1. The vehicle battery pack 1 includes a case unit 4 consisting of a lower case 2 and an upper case 3, one or more battery modules 6 arranged in an internal space 5 formed by the case unit 4, a battery ECU (Electronic Control Unit) 7 that monitors input / output to and from the battery module 6, cools the battery module 6, and acquires various sensor values ​​such as voltage, current, and pressure, and a cooler 8 that cools the battery module 6.

[0013] The lower case 2 is formed in a box shape with an opening at the top. The upper case 3 is attached to close the opening of the lower case 2 from above, thereby forming an internal space 5 as an enclosed space.

[0014] The battery module 6 is configured to have a plurality of battery cells 9 and partitions 10 arranged between the battery cells 9 .

[0015] The battery cells 9 and the partitions 10 are each formed in a flattened cubic shape and are arranged adjacent to each other in the thickness direction. The direction in which the battery cells 9 and the partitions 10 are adjacent to each other is, for example, the front-to-rear direction of the vehicle, and will be referred to as the "arrangement direction" in the following explanation.

[0016] The partitions 10 are filled with a cooling solvent, allowing efficient heat exchange between the partitions 10 and the battery cells 9 .

[0017] Each of the partitions 10 shown in Fig. 1 is adjacent to two battery cells 9. The two battery cells 9 adjacent to each other via the partitions 10 are able to exchange heat with each other, thereby enabling indirect heat exchange between the battery cells 9. As a result, when one battery cell 9 becomes too hot, the heat can be released to the adjacent battery cell 9 via the adjacent partition 10.

[0018] Under normal circumstances, the partition 10 serves to disperse heat generated locally in the battery cell 9 by exchanging heat between the battery cell 9 and the cooling solvent. However, when thermal runaway occurs, the cooling solvent evaporates, and the space filled with the cooling solvent is replaced by gas, significantly reducing the efficiency of heat exchange with the battery cell 9.

[0019] As a result, the partitions 10 promote heat exchange with the battery cells 9 under normal conditions, and suppress heat exchange with the battery cells 9 when thermal runaway occurs.

[0020] It is desirable to select the cooling solvent appropriately depending on the materials of each part constituting the vehicle battery pack 1. Specifically, if the material constituting the vehicle battery pack 1 is best one that melts at 100 degrees Celsius, it is desirable to select a cooling solvent that evaporates at temperatures below 100 degrees Celsius. This can prevent electrical short circuits and fires caused by melting of the material.

[0021] An example of the configuration of the partition section 10 will be described with reference to FIG.

[0022] The partition 10 is made up of a highly airtight case 11 and a heat insulating material 12 disposed inside the case 11 .

[0023] The heat insulating material 12 has a large number of pores 13, and a cooling solvent is held inside the pores 13. The heat insulating material 12 is made of, for example, porous ceramic.

[0024] The pores 13 are formed so as to be arranged two-dimensionally in a plane perpendicular to the thickness direction of the heat insulating material 12, and each pore has a uniform diameter. The diameter of the pores 13 is, for example, several mm (millimeters).

[0025] 3, a gap 14 is provided between the heat insulating material 12 and the case part 11, and as shown by the matte finish in the figure, the cooling solvent can move between the pores 13 through the gap 14. The width of the gap 14 is, for example, less than 1 mm.

[0026] Further, a discharge hole 10a is formed on the upper surface of the case portion 11 of the partition portion 10, through which the cooling solvent that has turned into vaporized gas is discharged to the outside.

[0027] The vaporized gas generated by vaporization of the cooling solvent in the pores 13 and the gap 14 passes through the gap 14 and moves upward, and is then discharged to the outside of the partition 10 through the discharge hole 10a.

[0028] In addition, a protrusion (not shown) of approximately the same height as the length of the gap 14 may be provided on the surface of the insulating material 12 facing the arrangement direction, so that a portion of the insulating material 12 comes into contact with the inner surface of the case portion 11.

[0029] By configuring the heat insulating material 12 to come into contact with the inner surface of the case 11 via the protrusions, it is possible to prevent deformation and damage to the case 11 when force is applied to the case 11 from the arrangement direction, and to prevent the cooling solvent filled inside from leaking out of the case 11. Therefore, the heat exchange function between the battery cells 9 via the cooling solvent can be maintained.

[0030] The vehicle battery pack 1 has a configuration for discharging vaporized gas generated by the evaporation of the cooling solvent filled inside the partition portion 10 .

[0031] Specifically, the vehicle battery pack 1 includes a connection duct 15 , a connecting duct 16 , a detection sensor 17 , and a terminal end 18 .

[0032] An example of the configuration of the battery ECU 7, battery cells 9, partition section 10, connection duct 15, connecting duct 16, detection sensor 17, and terminal section 18 is shown in FIG.

[0033] In FIG. 4, only a portion of the battery cells 9 and the partitions 10 included in the battery module 6 is shown.

[0034] A positive electrode terminal 19p and a negative electrode terminal 19m are provided on the top surface of the battery cell 9. In Fig. 1, the positive electrode terminal 19p and the negative electrode terminal 19m are not distinguished from each other and are simply referred to as "terminals 19".

[0035] The cables connected to the terminals 19 are not shown in FIGS.

[0036] A discharge hole 10a formed in the upper part of the partition portion 10 is connected to a connection duct 15 formed in a cylindrical shape and extending in the vertical direction.

[0037] The plurality of connection ducts 15 connected to each partition 10 are connected to a connecting duct 16, thereby communicating with each other. That is, the vaporized gas generated by vaporization of the cooling solvent in each partition 10 flows into the connecting duct 16 via the connecting duct 15.

[0038] The connecting duct 16 is formed in a cylindrical shape extending in the arrangement direction, and a detection sensor 17 is connected to a first end 16a, which is one end in the arrangement direction, and a terminal end 18 is connected to a second end 16b, which is the other end.

[0039] The detection sensor 17 is a sensor that detects the generation of vaporized gas resulting from evaporation of the cooling solvent in any of the partitions 10 connected to the connecting duct 16 .

[0040] The detection sensor 17 may be a sensor that detects a substance contained in the cooling solvent. For example, if the cooling solvent is a liquid containing a specific chemical substance, the detection sensor 17 may be a sensor that detects the chemical substance in the vaporized gas produced by the evaporation of the cooling solvent or a substance produced by a chemical reaction during the vaporization. If the cooling solvent is water, a humidity sensor or the like may be used as the detection sensor 17. If the cooling solvent is an alcohol-based solvent, the detection sensor 17 may be an alcohol sensor or the like.

[0041] Further, a pressure sensor 17A capable of detecting a pressure increase due to the generation of vaporized gas may be employed as the detection sensor 17. In the example shown in FIG.

[0042] The detection sensor 17 is capable of communicating with the battery ECU 7 by being connected to the battery ECU 7 via a communication line 20. That is, the detection sensor 17 outputs the detected sensor value to the battery ECU 7, and the battery ECU 7 executes the processing described below based on the input sensor value.

[0043] The terminal end 18 is formed with a discharge hole 18a for discharging vaporized gas to the outside in order to reduce the pressure inside the connecting duct 16. This prevents the pressure inside the connecting duct 16 from becoming too high, and prevents malfunction of the detection sensor 17, damage to the connecting duct 16, etc.

[0044] Valve mechanisms are provided inside the connection duct 15 and the terminal end portion 18. A specific description will be given with reference to FIG.

[0045] A vaporized gas release valve 21 (shown by a dashed line) is provided inside the connecting duct 15 to release the vaporized gas generated inside the partition 10 into the connecting duct 16. The vaporized gas release valve 21 automatically opens and closes depending on the pressure inside the partition 10. That is, when the pressure inside the partition 10 becomes higher than a predetermined threshold due to the generation of vaporized gas, the vaporized gas release valve 21 opens and adjusts the pressure inside the partition 10 so that it does not rise any further.

[0046] A pressure reducing valve 22 (shown by a broken line) is provided inside the terminal end portion 18. Similar to the vaporized gas release valve 21, the pressure reducing valve 22 opens at a predetermined timing when the pressure inside the connecting duct 16 increases, and the vaporized gas is released from the connecting duct 16.

[0047] 1, an exhaust duct is connected to the discharge hole 18a of the terminal end 18, and the vaporized gas generated by the evaporation of the cooling solvent is discharged to the outside of the vehicle through the exhaust duct, thereby preventing the vaporized gas from being drawn into the vehicle interior and improving the safety of the occupants.

[0048] 1 monitors the voltage, temperature, SOC (State Of Charge), SOH (State Of Health), etc. of each component to ensure an appropriate power supply from the high-voltage battery cells 9 or battery modules 6. In this embodiment, the battery ECU 7 also acquires a sensor value from a pressure sensor 17A as the detection sensor 17 and determines whether or not thermal runaway has occurred in the battery cells 9.

[0049] When the battery ECU 7 detects the occurrence of thermal runaway in the battery cell 9, the battery ECU 7 performs a process to electrically cut off the battery cell 9. Furthermore, when the battery ECU 7 or a control unit such as another ECU detects thermal runaway, it instructs the occupants to evacuate.

[0050] As shown in FIG. 1, the cooler 8 is disposed adjacent to the lower part of the case unit 4 and cools the battery module 6 from below.

[0051] A cooling medium such as water is circulated inside the cooler 8, and the cooling medium is cooled by a chiller or the like (not shown), thereby maintaining the cooling effect on the battery module 6.

[0052] 2. Flowchart The battery ECU 7 or another ECU (hereinafter simply referred to as the "controller") performs processing to detect the occurrence of thermal runaway in the battery cell 9. The processing executed by the controller will be described with reference to FIG.

[0053] The control unit determines whether the system is in an on state in step S101 of Fig. 6. The on state of the system refers to a process of determining whether the control system of the vehicle is in an activated state, and may be, for example, a process of determining whether the vehicle is in a state where it can be driven.

[0054] If it is determined that the system is not in the ON state, the control unit repeats the process of step S101.

[0055] On the other hand, if it is determined that the system is in the on state, the control unit starts acquiring sensor values ​​by starting sensing using the detection sensor 17 (hereinafter referred to as pressure sensor 17A) in step S102.

[0056] In step S103, the control unit starts counting up the detection time, which is defined as the time elapsed since the pressure sensor 17A started acquiring the pressure sensor value.

[0057] The control unit starts the initialization process of the pressure sensor 17A in step S104, and then determines whether the initialization time has elapsed by determining whether the detection time has reached the initialization time in the following step S105. The initialization time is the time required for the initialization process of the pressure sensor 17A started in step S104 to be completed. That is, the control unit waits in step S105 until the initialization process is completed.

[0058] In the initialization process, it is confirmed whether the pressure sensor value acquired by the pressure sensor 17A is a normal value. Therefore, the initialization process is performed after the start of acquiring the pressure sensor value in step S102.

[0059] In step S106, the control unit calculates the amount of change in the pressure sensor value. The pressure sensor value has been acquired every few hundred milliseconds or every second since the processing in step S103. In step S106, the control unit calculates the amount of change by calculating the difference between the latest pressure sensor value and the previous value.

[0060] In step S107, the control unit determines whether the amount of change in the pressure sensor value calculated earlier is equal to or greater than the thermal runaway determination threshold. If thermal runaway occurs, the pressure sensor value will continue to increase for a while thereafter. The control unit can detect the onset of thermal runaway by detecting an increase in the pressure sensor value.

[0061] Note that the control unit of this configuration does not determine whether the pressure sensor value is equal to or greater than the threshold value, but rather whether the change in the pressure sensor value is equal to or greater than the threshold value. When the pressure sensor 17A fails, it may fall into a state where a predetermined sensor value continues to be output. In this case, if a configuration that determines whether the pressure sensor value is equal to or greater than the threshold value is adopted, there is a possibility that the occurrence of thermal runaway may be erroneously detected. On the other hand, the present configuration that determines whether the change in the pressure sensor value is equal to or greater than the threshold value can prevent erroneous detection of the occurrence of thermal runaway.

[0062] If it is determined that the change in the pressure sensor value is equal to or greater than the thermal runaway threshold, the control unit starts counting up the pressure rise elapsed time in step S108. The pressure rise elapsed time is the time elapsed since the pressure rise occurred.

[0063] In step S109, the control unit determines whether the elapsed pressure rise time is equal to or greater than the debounce threshold. The debounce threshold is set to prevent erroneous thermal runaway determination due to debouncing that may occur when the change in the pressure sensor value exceeds the thermal runaway determination threshold for the first time, and may be set to several seconds, for example. In other words, by checking that the change in the pressure sensor value continues to exceed the thermal runaway determination threshold for a certain period based on the debounce threshold (for example, several seconds), erroneous thermal runaway determination can be prevented.

[0064] If the pressure rise elapsed time is less than the debounce threshold, the control unit returns to the determination process of step S107.

[0065] If it is determined in step S107 that the amount of change in the pressure sensor value is less than the thermal runaway determination threshold, the control unit resets the pressure rise elapsed time to zero in step S110 and returns to the process of step S107.

[0066] In step S109, if it is determined that the pressure rise elapsed time is equal to or greater than the debounce threshold, that is, if a pressure rise of a certain level or greater is continuously detected, the control unit sets the thermal runaway flag to "1" in step S111. That is, the control unit detects the occurrence of thermal runaway in step S111.

[0067] In step S112, the control unit performs a response process to the occurrence of thermal runaway. In the response process, for example, an electrical cutoff process is performed for each battery cell 9 in the battery module 6, and further, an instruction to occupants to evacuate is issued. The instruction to occupants to evacuate may be issued, for example, via a monitor or the like placed in a position visible to the driver, or may be issued by audio output.

[0068] 3. Modifications The following describes modifications to the above-described vehicle battery pack 1. As shown in Fig. 7, a vehicle battery pack 1B may be configured to include a battery module 6B having a smaller number of partitions 10 than in the above-described example.

[0069] Specifically, the battery cells 9 of the battery module 6B are arranged adjacent to one another in the arrangement direction, and a partition 10 is arranged adjacent to the other one in the arrangement direction. In other words, one partition 10 is provided adjacent to each pair of two battery cells 9.

[0070] As a result, all of the battery cells 9 are adjacent to the partitions 10, allowing for efficient heat transfer between the battery cells 9, and the reduced number of partitions 10 allows for a more compact battery module 6B.

[0071] Therefore, the length of the vehicle battery pack 1B in the arrangement direction can be shortened, and the space required for arranging the vehicle battery pack 1B can be reduced. Also, the degree of freedom in arranging the vehicle battery pack 1B can be improved. Furthermore, the degree of freedom in arranging vehicle equipment other than the vehicle battery pack 1B can be improved, and the degree of freedom in the shape of the vehicle equipment can be improved.

[0072] In the above-described vehicle battery pack 1, an example has been shown in which one detection sensor 17 is provided at the first end 16a of the connecting duct 16, but a detection sensor 17 may also be provided for each battery cell 9.

[0073] This makes it possible to identify the battery cell 9 in which thermal runaway has occurred. Therefore, it is possible to reduce the number of battery cells 9 that are the target of electrical cutoff processing, making it easier to ensure the minimum power required to move the vehicle to a safe location.

[0074] The pressure reducing valve 22 arranged inside the terminal end portion 18 may be opened and closed automatically when the pressure inside the connecting duct 16 reaches a predetermined pressure, or may be opened and closed under the control of the battery ECU 7. For example, the battery ECU 7 controls the pressure reducing valve 22 to an open state when the sensor value of the pressure sensor 17A is equal to or greater than a predetermined threshold, and controls the pressure reducing valve 22 to a closed state when the sensor value is less than the predetermined threshold.

[0075] If the pressure reducing valve 22 is configured to open and close naturally, variations in the timing at which it opens will occur due to manufacturing errors in the pressure reducing valve 22. On the other hand, if it is configured to be controlled in accordance with the sensor value of the pressure sensor 17A, the variations in the opening timing can be reduced by suppressing the detection error of the pressure sensor 17A, and failures of the pressure sensor 17A, etc. can be suppressed.

[0076] The vehicle battery pack 1 may employ a liquid cooling system in which the cooler 8 is disposed below the case unit 4, or an air cooling system that does not require the cooler 8 to be disposed below the case unit 4. This allows the vehicle battery pack 1 to be made smaller.

[0077] The above examples may be combined in any way.

[0078] 4. Summary As described in the above examples, a vehicle battery pack 1 (1B) mounted on an electric vehicle, such as a hybrid vehicle or an electric vehicle, configured to drive wheels using the power of an electric motor, includes a battery module 6 (6B) having a plurality of battery cells 9 and partitions 10 arranged between the plurality of battery cells 9 in the arrangement direction of the plurality of battery cells 9 (e.g., the front-to-rear direction of the vehicle), with heat insulating material 12 disposed therein and filled with a cooling solvent, vaporized gas release valves 21 that are activated by a pressure increase associated with the evaporation of the cooling solvent in the partitions 10 and release the vaporized gas generated by the vaporization from the partitions 10, a connecting duct 16 connecting the plurality of vaporized gas release valves 21, and a detection sensor 17 (e.g., a pressure sensor 17A) that detects the release of the vaporized gas from the vaporized gas release valves 21. As a result, while the cooling solvent is present in liquid form in the partitions 10, heat is efficiently transferred between two adjacent battery cells 9 via the partitions 10. When a battery cell 9 experiences thermal runaway, the temperature rise of the battery cell 9 causes the cooling solvent to vaporize and be released to the outside through the partition 10. This significantly impairs thermal conductivity between the battery cells 9, as the two battery cells 9 are adjacent to each other via the insulating material 12 and the vaporized gas. Furthermore, by measuring the pressure inside the connecting duct 16 using the sensor value of a detection sensor 17, such as the pressure sensor 17A, the generation of vaporized gas resulting from the evaporation of the cooling solvent can be detected. This improves the cooling performance of the battery cell 9 when no thermal runaway occurs and prevents the spread of fire to surrounding battery cells 9 when thermal runaway does occur. By detecting the occurrence of thermal runaway in a battery cell 9, the controller can quickly notify the driver, thereby ensuring time to drive the vehicle to a safe location and stop it, while improving the safety of passengers. Furthermore, by connecting multiple battery cells 9 via the connecting duct 16, only one detection sensor 17 is required for each battery module 6. This reduces the number of components.

[0079] The vehicle battery pack 1 (1B) may also have a pressure reducing valve 22 for reducing the pressure inside the connecting duct 16. When the cooling solvent vaporizes due to heat generated by thermal runaway of the battery cells 9, causing a pressure increase, the pressure reducing valve 22 operates to reduce the pressure inside the partition section 10. The pressure when the pressure reducing valve 22 is opened is set to be higher than the pressure when the thermal runaway flag is set to "1". This prevents the pressure reducing valve 22 from being opened and the pressure inside the connecting duct 16 from being reduced before thermal runaway is detected.

[0080] Furthermore, the insulating material 12 in the vehicle battery pack 1 (1B) may have multiple pores 13 for retaining the cooling solvent. For example, multiple pores 13 are provided in the partition 10, which is shaped like a flattened cube across a surface perpendicular to the arrangement direction, and the arrangement direction of the multiple pores 13 is the axial direction. Therefore, the cooling solvent filled in the pores 13 is adjacent to the two battery cells 9 via the case 11, thereby improving thermal conductivity. Furthermore, a configuration using an insulating material 12 with multiple pores 13 improves the strength of the partition 10 and prevents deformation of the partition 10 due to external forces compared to a configuration in which the cooling solvent is filled in a hollow internal space without the insulating material 12. Furthermore, the partition 10 is pressed strongly against the battery cells 9 in the arrangement direction, thereby improving the efficiency of heat exchange between the cooling solvent and the battery cells 9. Therefore, it is preferable to place a heat insulating material 12 in the internal space of the partitions 10 in order to prevent the partitions 10 from being deformed by being pressed against the battery cells 9. It is possible to improve the resistance to deformation caused by pressure from the arrangement direction of the partitions 10 by making the case parts 11 of the partitions 10 sturdy, but this would result in an increase in the weight of the partitions 10. By including the heat insulating material 12 in the partitions 10, it is possible to avoid the weight of the partitions 10 being increased.

[0081] Additionally, the pores 13 in the vehicle battery pack 1 (1B) may be cylindrical pores with their axial direction aligned in the arrangement direction (e.g., the longitudinal direction of the vehicle). By making the pores 13 cylindrical, convection within the pores 13 is facilitated, enabling efficient heat exchange between the battery cells 9 and the cooling medium. This allows for high cooling performance.

[0082] Furthermore, the detection sensor 17 in the vehicle battery pack 1 (1B) may be a pressure sensor 17A. By acquiring a sensor value from the pressure sensor 17A, the controller (battery ECU 7) can detect the generation of vaporized gas caused by the evaporation of the cooling solvent.

[0083] REFERENCE SIGNS LIST 1, 1B Vehicle battery pack 6, 6B Battery module 9 Battery cell 10 Partition 12 Heat insulating material 13 Pore 16 Connecting duct 17 Detection sensor 17A Pressure sensor 21 Vaporized gas release valve 22 Pressure reducing valve

Claims

1. A vehicle battery pack comprising: a battery module having a plurality of battery cells; a partition section disposed between the plurality of battery cells in the arrangement direction of the plurality of battery cells, with a heat insulating material disposed therein and filled with a cooling solvent; a vaporized gas release valve that is activated by a pressure increase accompanying evaporation of the cooling solvent in the partition section and releases vaporized gas generated by the evaporation from the partition section; a connecting duct that connects the plurality of vaporized gas release valves; and a detection sensor that detects the release of the vaporized gas from the vaporized gas release valve.

2. The vehicle battery pack according to claim 1, further comprising a pressure reducing valve for reducing the pressure inside the connecting duct.

3. The vehicle battery pack according to claim 1, wherein the heat insulating material has a plurality of pores that retain the cooling solvent.

4. The vehicle battery pack according to claim 3, wherein the pores are cylindrical holes whose axial direction is in the arrangement direction.

5. A vehicle battery pack according to any one of claims 1 to 4, wherein the detection sensor is a pressure sensor.