Battery pack

Abstract

A battery pack (10) comprises a case (11) for accommodating a battery (12). The case (11) is provided with a first chamber (111) that accommodates the battery (12), a second chamber (112) that is adjacent to the first chamber (111), and a partition wall (113) that separates the first chamber (111) and the second chamber (112). The second chamber (112) is provided with a dehumidifying mechanism (3), a communication part (171) that communicates with the outside, and a hydrophobic permeable membrane (172) that blocks the communication part (171) and that allows passage of only gas. The partition wall (113) is provided with a first valve (18) that is open when a differential pressure (ΔP) obtained by subtracting the pressure (P1) of the first chamber (111) from the pressure (P2) of the second chamber (112) is less than a first differential pressure (ΔP1), and a second valve (19) that is open when the differential pressure (ΔP) exceeds a second differential pressure (ΔP2).

Description

Battery pack

[0001] This invention relates to a battery pack installed in a vehicle.

[0002] Conventionally, battery packs containing batteries are known (for example, Patent Document 1). The battery pack of Patent Document 1 houses a battery, a blower fan, a temperature sensor, a humidity sensor, and a cooling device, etc. The air conditioning control device controls the blower fan and the evaporator of the cooling device based on the temperature detected by the temperature sensor, determines whether dehumidification is necessary based on the humidity detected by the humidity sensor, and dehumidifies by rapidly cooling the evaporator to generate condensation.

[0003] Japanese Patent Publication No. 2016-146236

[0004] However, the apparatus described in Patent Document 1 requires a blower fan, various sensors, and a dedicated cooling device, which complicates the configuration and necessitates the construction of a system that controls the blower fan and cooling device based on these sensors.

[0005] The present invention aims to provide a battery pack that can dehumidify the battery with a simple configuration.

[0006] A battery pack according to a first aspect of the present invention is a battery pack mounted on a vehicle and comprises a case for housing a battery. The case comprises a first chamber in which the battery is housed, a second chamber adjacent to the first chamber, and a partition wall separating the first chamber and the second chamber. A dehumidification mechanism is provided in the second chamber. The second chamber is also provided with a communication section that communicates with the outside of the case, and the communication section is closed with a hydrophobic permeable membrane that allows only gas to pass through. The partition wall is provided with a first valve and a second valve. The first valve is opened when the differential pressure obtained by subtracting the pressure of the first chamber from the pressure of the second chamber is less than the first pressure difference, and is closed when it is greater than or equal to the first pressure difference. The second valve is opened when the differential pressure obtained by subtracting the pressure of the first chamber from the pressure of the second chamber exceeds the second pressure difference, and is closed when it is less than or equal to the second pressure difference.

[0007] In such a battery pack, as the temperature of the first chamber rises, the pressure in the first chamber increases. When the differential pressure obtained by subtracting the pressure in the first chamber from the pressure in the second chamber becomes less than the first pressure difference, the first valve opens, and the high-temperature gas in the first chamber flows into the second chamber. The gas that has flowed into the second chamber is dehumidified by the dehumidification mechanism. Further, as the temperature of the first chamber drops, the pressure in the first chamber decreases. When the differential pressure obtained by subtracting the pressure in the first chamber from the pressure in the second chamber exceeds the second pressure difference, the second valve opens, and the dehumidified air in the second chamber flows into the first chamber. As a result, dehumidification within the battery pack becomes possible with a simple configuration.

[0008] Schematic diagram showing an overview of a vehicle equipped with the battery pack of the present embodiment. Perspective view showing an example of the battery pack of the present embodiment. Cross-sectional view showing an example of the battery pack of the present embodiment. Diagram showing another example of the inclined surface provided in the second chamber. Cross-sectional view showing the schematic configuration of the drain part of the present embodiment. Cross-sectional view showing the schematic configuration of the drain part of the present embodiment. Cross-sectional view showing the schematic configuration of the second chamber in a modified example.

[0009] Hereinafter, an embodiment of the present disclosure will be described. FIG. 1 is a schematic diagram showing an overview of a vehicle 1 equipped with a battery pack 10 of the present embodiment. FIG. 2 is a perspective view of the battery pack 10 of the present embodiment, and FIG. 3 is a cross-sectional view of the battery pack 10. As shown in FIG. 1, the battery pack 10 of the present embodiment is mounted on the vehicle 1. Although not shown in the figure, the vehicle 1 is provided with a drive source such as a motor, a traveling mechanism that causes the vehicle 1 to travel by the driving force of the drive source, a steering mechanism, an air conditioner, various sensors, and a control controller for controlling each component. Further, as shown in FIG. 1, the vehicle 1 is provided with a cooling mechanism 2 for cooling the drive source, the traveling mechanism, the air conditioner, and the like. The battery pack 10 supplies electric power to each component of the vehicle 1 as described above.

[0010] The cooling mechanism 2 is generally arranged on the front Fr side of the vehicle 1. Since many heat sources such as drive sources like motors and heat sources like air conditioners are arranged on the front Fr side of the vehicle 1, it is preferable to provide the cooling mechanism 2 on the front Fr side of the vehicle 1 in order to cool these heat sources. A refrigerant pipe 3 through which a refrigerant flows is connected to the cooling mechanism 2, and the refrigerant pipe 3 extends toward each component of the vehicle 1 to be cooled. Although details will be described later, in this embodiment, a part of the refrigerant pipe 3 contacts the battery pack 10.

[0011] As shown in FIG. 2, the battery pack 10 has, for example, a flat shape in which the lengths in the Y direction (vehicle width direction) and the X direction (vehicle length direction) are longer than the Z direction (vehicle height direction), and is arranged at the center of the vehicle 1. In the following description, the vehicle length direction from the rear R to the front Fr of the vehicle 1 is defined as the X direction, the vehicle width direction from the left side to the right side of the vehicle 1 is defined as the Y direction, and the vehicle height direction from the road surface toward the direction perpendicular to the road surface is defined as the Z direction.

[0012] As shown in FIG. 3, the battery pack 10 includes a case 11 and a battery 12 housed in the case 11. The case 11 includes a front surface portion 11F arranged on the +X side (front Fr side) as shown in FIG. 2, a rear surface portion 11R arranged on the -X side (rear R side), side surface portions 11S arranged on the ±Y sides (see FIG. 2), a bottom surface portion 11D arranged on the -Z side, and a top surface portion 11U arranged on the +Z side. The case 11 maintains the internal space surrounded by these wall surfaces (11F, 11R, 11S, 11D, 11U) airtight. The case 11 includes a first room 111, a second room 112, and a partition wall 113 that separates the first room 111 and the second room 112 in the internal space.

[0013] The first room 111 is enclosed by a rear section 11R, a side section 11S, a bottom section 11D, a top section 11U, and a partition wall 113, and is a space in which the interior is kept airtight. One or more batteries 12 are housed in the first room 111. The battery 12 in this embodiment is, for example, a secondary battery containing a solid electrolyte, and its temperature changes with charging and discharging. Although detailed illustrations are omitted, the all-solid-state secondary battery 12 is configured to have, for example, a laminate formed by stacking multiple battery cells, and this laminate is housed in a battery case. Each battery 12 is provided with busbars to which the electrode foils of the housed battery cells are connected. The first room 111 may also house wiring connected to the busbars, a junction box (J / B) where the connection points and branching points of the wiring are concentrated, and a battery management system (BMS) for managing and controlling the charging and discharging of each battery 12.

[0014] In the first chamber 111, a PRD 13 (Pressure Relief Device: a safety valve as defined herein) is positioned on a wall portion not adjacent to the second chamber 112. The wall portion not adjacent to the second chamber 112 is at least one of the rear portion 11R, the side portion 11S, and the top portion 11U. In the example shown in Figure 3, the PRD 13 is positioned on the rear portion 11R of the first chamber 111. This PRD 13 is a valve that opens when the pressure in the first chamber 111 exceeds a predetermined pressure value, and discharges the gas inside the first chamber 111 to the outside of the case 11. The pressure at which the PRD 13 operates is sufficiently greater than the pressure at which the first valve 18 and the second valve 19, which will be described later, operate. As will be described in detail later, in this embodiment, the first valve 18 operates at the pressure P of the second chamber 112. ２ Pressure P from the first room 111 １ The differential pressure ΔP obtained by subtracting the predetermined first pressure difference ΔP １ It activates and releases when the pressure falls below (for example, -10 kPa). In contrast, the PRD13 operates when the differential pressure ΔP is less than the first pressure difference ΔP １ A third pressure difference ΔP is smaller than this. ３ It activates and opens when the pressure falls below (for example, -20 kPa). In this embodiment, the pressure P in the second chamber 112 ２is maintained at the same pressure as the external pressure of the case 11, for example, the atmospheric pressure. That is, the pressure P of the first chamber 111 １ is greater than the pressure outside the case 11 by |ΔP １ |, the first valve 18 is opened. Furthermore, as the pressure P １ increases and becomes greater than the pressure outside the case 11 by |ΔP ３ |, the PRD 13 is opened. When the PRD 13 is opened, the gas in the first chamber 111 is emergently discharged to the outside of the case 11. A plurality of such PRDs 13 may be provided. For example, the PRD 13 may be installed on each of the back surface portion 11R, side surface portions 11S, and top surface portion 11U, or a plurality of PRDs 13 may be arranged on the back surface portion 11R. In this case, when the pressure in the first chamber 111 becomes abnormally high, it is possible to more quickly reduce the pressure.

[0015] The second chamber 112 is a space formed by being surrounded by the front surface portion 11F, a pair of side surface portions 11S, the bottom surface portion 11D, the top surface portion 11U, and the partition wall 113. That is, the second chamber 112 is arranged on the +X side (front Fr side) of the first chamber 111 via the partition wall 113.

[0016] The second chamber 112 is in contact with a refrigerant pipe 3 through which a refrigerant flows. Here, "the refrigerant pipe 3 is in contact with the second chamber 112" includes not only the case where the refrigerant pipe 3 is in contact with the outer surface of the wall portion (11F, 11D, 11U, 11S) that constitutes the second chamber 112, but also the case where the refrigerant pipe 3 is installed penetrating the second chamber 112 and the outer surface of the pipe is in contact with the gas inside the second chamber 112. In the example shown in Figure 3, the refrigerant pipe 3 is shown in contact with the bottom portion 11D of the second chamber 112, but it may also be in contact with the front portion 11F, the top portion 11U, or the side portion 11S. However, if the refrigerant pipe 3 is positioned close to the first chamber 111, the gas inside the first chamber 111 will also be cooled, causing condensation inside the first chamber 111 and adversely affecting the battery 12. Therefore, it is preferable that the refrigerant piping 3 is in contact with the second chamber 112 on the opposite side from the first chamber 111, that is, on the +X side of the center point of the second chamber 112 in the X direction. By the refrigerant piping 3 being in contact with the second chamber 112, it becomes possible to cool the gas inside the second chamber 112. Furthermore, by generating condensation through the cooling of the gas inside the second chamber 112, it becomes possible to dehumidify the gas inside the second chamber 112. In this embodiment, the configuration in which the refrigerant piping 3 is in contact with the second chamber 112 means that it functions as a dehumidification mechanism of this disclosure.

[0017] Furthermore, in this embodiment, an inclined surface 15 is provided on the bottom surface 11D of the second room 112. The inclined surface 15 slopes from upward (+Z side) to downward (-Z side) to guide water droplets (condensation water) generated by condensation. For example, in the example shown in Figure 3, an inclined surface 15 is provided from a part of the front surface 11F of the second room 112, sloping toward the -Z side as it moves toward the -X side. A drainage section 16 is provided at the bottom surface 11D, which is the lower end 151 of the inclined surface 15, and the condensation water is guided to the drainage section 16.

[0018] Note that the inclined surface 15 is not limited to the configuration shown in Figure 3, and any inclination that uses the inclination to guide condensation droplets to the drainage section 16 located on the -Z side is acceptable. Figure 4 shows another example of an inclined surface provided in the second chamber 112. For example, as shown in Figure 4, there may be an inclined surface 15A that slopes towards the -Z side as you move from the front portion 11F toward the -X side, and an inclined surface 15B that slopes towards the -Z side as you move from the partition wall 113 toward the +X side. In this case, it is preferable that the lower ends 151 of the inclined surfaces 15A and 15B are at approximately the same position, and that the drainage section 16 is provided at the lower ends 151. In the example in Figure 4, only the XZ cross section is shown, but an inclined surface with a similar configuration may be applied to the YZ cross section. That is, a funnel-shaped inclined surface may be provided centered on the drainage section 16 provided on the bottom portion 11D.

[0019] Figures 5A and 5B are cross-sectional views showing the schematic configuration of the drain section 16 of this embodiment. The drain section 16 has a return structure and is configured to suppress backflow. For example, the drain section 16 shown in Figures 5A and 5B includes a storage section 161, a discharge passage 162, a discharge valve 163, and a biasing member 164. In this drain section 16, the storage section 161 is formed in an inner circumferential cylindrical shape, and the -Z side end communicates with a discharge passage 162 which has a larger pipe diameter than the storage section 161. A discharge valve 163 is positioned at the boundary between the storage section 161 and the discharge passage 162, and the discharge valve 163 is biased toward the storage section 161 by a biasing member 164. The discharge section of this disclosure is composed of the discharge passage 162, the discharge valve 163, and the biasing member 164. In such a drain section 16, if the amount of water stored in the storage section 161 is less than a predetermined amount, the discharge valve 163 closes the storage section 161 due to the biasing force of the biasing member 164, as shown in Figure 5A. As a result, water is not discharged from the storage section 161 to the discharge passage 162. However, this also prevents problems such as water flowing back from the discharge passage 162 towards the storage section 161, or water sprayed from outside the case 11 entering the case 11. On the other hand, when the amount of water stored in the storage section 161 exceeds a predetermined amount, as shown in Figure 5B, the weight of the stored water causes the discharge valve 163 to move to the -Z side against the biasing force of the biasing member 164. As a result, water is discharged from the storage section 161 to the outside of the case 11 via the discharge passage 162.

[0020] The return structure of the drain section 16 is not limited to the configuration shown in Figures 5A and 5B, as long as it is configured such that a predetermined amount of water is stored, the stored water is discharged to the outside of the case 11, and the entry or backflow of water from the case 11 is suppressed. For example, a U-shaped trap structure or the like may be used as the return structure of the drain section 16.

[0021] Furthermore, the second chamber 112 is provided with a pressure adjustment unit 17 on at least one of the wall portions not adjacent to the first chamber 111, namely the front portion 11F, the side portion 11S, and the top portion 11U. In the example shown in Figure 3, the pressure adjustment unit 17 is located on the front portion 11F of the second chamber 112. This pressure adjustment unit 17 maintains a constant pressure in the second chamber 112, for example, by maintaining the pressure in the second chamber 112 to be equal to the pressure outside the case 11 (e.g., atmospheric pressure). Specifically, the pressure adjustment unit 17 is composed of a communication portion 171 that penetrates the wall portion (the front portion 11F in the example of Figure 3) and a hydrophobic permeable membrane 172 that closes the communication portion 171. The permeable membrane 172 is a gas permeable membrane that allows only gas to pass through and prevents the entry of liquids and solids.

[0022] The permeable membrane 172 may be configured to selectively allow only specific gases to pass through. For example, a permeable membrane 172 that allows harmless gases such as oxygen and nitrogen to pass through while suppressing the permeation of corrosive gases such as hydrogen sulfide and carbon dioxide, and acidic gases, may be used. By using such a permeable membrane 172, the inconvenience of corrosive gases and acidic gases entering the inside of the battery pack 10 can be suppressed, and corrosion and oxidation of the battery 12 can be suppressed. In addition, by suppressing the discharge of corrosive gases and acidic gases generated inside the battery pack 10 to the outside of the case 11, an improvement in the environment can be expected. Examples of such permeable membranes 172 include polyimide-based and polysulfone-based permeable membranes, composite membranes formed by laminating membranes with different properties, and inorganic membranes such as ceramic membranes and zeolite membranes.

[0023] The partition wall 113 is a wall provided between the first room 111 and the second room 112. As shown in Figure 3, the partition wall 113 is provided with a first valve 18 and a second valve 19. When either the first valve 18 or the second valve 19 is opened, the first room 111 and the second room 112 are connected through the opened valve.

[0024] The first valve 18 controls the pressure P of the second chamber 112. ２ From there, the pressure P in the first room 111 １ The differential pressure ΔP obtained by subtracting the predetermined first pressure difference ΔP １ It opens when the pressure difference ΔP is less than the first pressure difference ΔP １ The system is closed if the above conditions are met. Here, the first pressure difference ΔP １ It is a negative value. In other words, the pressure P in the first room 111. １ However, the pressure P in the second room 112 ２ Rather than the predetermined value |ΔP １ If the value is greater than or equal to the above, the first valve 18 is opened. When the first valve 18 is opened, gas flows from the first chamber 111 to the second chamber 112 through the first valve 18.

[0025] Furthermore, it is preferable that the first valve 18 is positioned on the bottom surface 11D side of the partition wall 113. That is, the center position Z in the height direction of the partition wall 113. Ｃ (See Figure 3) It is preferable that it be located on the -Z side. In this case, gases heavier than air can be preferentially discharged into the second chamber 112. Gases heavier than air include corrosive gases such as hydrogen sulfide and carbon dioxide, as well as acidic gases. In this embodiment, by providing the first valve 18 on the bottom surface 11D side of the partition wall 113, these corrosive and acidic gases can be preferentially discharged into the second chamber 112. This makes it possible to suppress corrosion and oxidation of the battery 12, junction box, battery management system, etc., which are located in the first chamber 111.

[0026] Furthermore, the first valve 18 is located at the center position Z in the height direction. ＣIt is more preferable that the first valve 18 be positioned closer to the bottom surface 11D and further +Z from the bottom surface 11D by a predetermined distance. By positioning the first valve 18 further +Z from the bottom surface 11D by a predetermined distance, the inconvenience of condensation water generated in the second chamber 112 flowing into the first chamber 111 can be suppressed. That is, when the first valve 18 is opened, the pressure P in the first chamber 111 １ However, the pressure P in the second room 112 ２ When the temperature is higher than the first chamber 111, gas flows from the first chamber 111 to the second chamber 112. Due to this gas flow, even if condensation occurs in the second chamber 112, the entry of water from the first valve 18 into the first chamber 111 is suppressed. However, if the road surface is sloped and the rear R side of the vehicle 1 is lower than the front Fr side, or when the vehicle 1 is accelerating, condensed water may move to the rear R side. In this case, if the first valve 18 is in contact with the bottom surface 11D, there is a risk that condensed water will enter the first chamber 111. To address this, by positioning the first valve 18 on the bottom surface 11D side of the partition wall 113, and at a position (higher position) a predetermined distance away from the bottom surface 11D, the movement of condensed water into the first chamber 111 can be suppressed.

[0027] The second valve 19 controls the pressure P of the second chamber 112. ２ From there, the pressure P in the first room 111 １ The differential pressure ΔP obtained by subtracting the predetermined second pressure difference ΔP ２ It is opened when it exceeds the second pressure difference ΔP. ２ The blockage occurs when the following conditions are met: where the second pressure difference ΔP ２ This is a positive value. In other words, the pressure P in the second room 112. ２ However, the pressure P in the first room 111 １ Rather than the predetermined value |ΔP ２ If the value is greater than or equal to |, the second valve 19 is opened. Therefore, when the second valve 19 is opened, gas flows from the second chamber 112 to the first chamber 111 through the second valve 19. In this embodiment, the first pressure difference ΔP １ If it is a negative value, the second pressure difference ΔP ２ Since it is a positive value, the differential pressure ΔP is equal to the first pressure difference ΔP １ The above is the second pressure difference ΔP ２Within the following range, both the first valve 18 and the second valve 19 are closed.

[0028] Furthermore, it is preferable that the second valve 19 is positioned on the top surface 11U side of the partition wall 113. That is, at the center position (Z) in the height direction of the partition wall 113. Ｃ It is preferable that it be located on the +Z side of ). This suppresses the inflow of gases heavier than air into the first chamber 111. In other words, by suppressing the inflow of corrosive and acidic gases into the first chamber 111, corrosion and oxidation of the battery 12, junction box, battery management system, etc., located in the first chamber 111 can be suppressed.

[0029] Furthermore, by providing the second valve 19 on the top surface 11U side of the partition wall 113, the intrusion of condensation water into the first chamber 111 can also be suppressed. As described above, when the second valve 19 is opened, the pressure P of the second chamber 112 ２ However, the pressure P in the first room 111 １ When the temperature is higher than the specified value, gas flows from the second chamber 112 towards the first chamber 111. If the second valve 19 were located on the bottom surface 11D side of the partition wall 113, there would be a risk that water droplets that flowed down to the bottom surface 11D side with the gas flow would move from the second chamber 112 to the first chamber 111. In contrast, in this embodiment, the second valve 19 is located on the top surface 11U side of the partition wall 113, thereby suppressing the movement of water generated by condensation into the first chamber 111.

[0030] [Cooling and Dehumidification Mechanism of Battery Pack 10] Next, the cooling of the battery 12 and the dehumidification of the internal space of the battery pack 10 in this embodiment will be described in more detail. The battery pack 10 in this embodiment is a battery pack 10 mounted on a vehicle 1, and when the power to the vehicle 1 is turned on and operation (operation) begins, the battery 12 is charged and discharged, causing the temperature of the battery 12 to rise. As the temperature of the battery 12 rises, the temperature of the first chamber 111 also rises accordingly, and the pressure P of the first chamber 111 rises. １ It will rise.

[0031] Here, the pressure P in the second chamber 112 ２From there, the pressure P in the first room 111 １ The differential pressure ΔP obtained by subtracting the first pressure difference ΔP is the first pressure difference ΔP. １ The above is the second pressure difference ΔP ２ If the following conditions are met, the first valve 18 and the second valve 19 are closed, and there is no movement of gas between the first chamber 111 and the second chamber 112. Due to the rise in pressure P1 in the first chamber 111, the differential pressure ΔP becomes the first pressure difference ΔP １ (Pressure P in the first room 111) becomes less than １ However, the pressure P in the second room 112 ２ Rather than the predetermined value |ΔP １ When the temperature exceeds |, the first valve 18 is opened. As a result, the high-temperature gas in the first chamber 111 flows from the first valve 18 into the second chamber 112.

[0032] Since the refrigerant piping 3 is in contact with the second chamber 112, the gas in the second chamber 112 is cooled by the refrigerant piping 3. This cooling also causes condensation, and the condensed water flows from the inclined surface 15 of the second chamber 112 to the drain section 16. As a result, the gas in the second chamber 112 is cooled and dehumidified.

[0033] Furthermore, since the second chamber 112 is equipped with a pressure adjustment unit 17, even if gas flows from the first chamber 111 to the second chamber 112, the pressure in the second chamber 112 is maintained at a predetermined pressure (for example, atmospheric pressure). Therefore, as gas flows out from the first chamber 111 to the second chamber 112, the pressure in the first chamber 111 approaches the predetermined pressure, and the differential pressure ΔP becomes the first pressure difference ΔP １ The above is the second pressure difference ΔP ２ The first valve 18 is closed when the range falls below the specified limit.

[0034] Subsequently, as the charge / discharge rate of the battery 12 decreases, the temperature of the battery 12 will drop, and consequently, the pressure P in the first chamber 111 will decrease. １ It also decreases. Pressure P in the first room 111 １ As the pressure decreases, the differential pressure ΔP becomes the second pressure difference ΔP ２ (Pressure P in the second room 112) ２ However, the pressure P in the first room 111 １ Rather than the predetermined value |ΔP ２When the temperature exceeds |, the second valve 19 is opened. As a result, the gas in the second chamber 112 flows into the first chamber 111 from the second valve 19. As described above, the gas in the second chamber 112 is cooled and dehumidified by the refrigerant piping 3, so when this gas flows into the first chamber 111, the temperature of the battery 12 can be further cooled and the humidity of the first chamber 111 can be lowered.

[0035] Then, due to the inflow of gas from the second chamber 112 to the first chamber 111, the pressure in the first chamber 111 changes to the pressure P in the second chamber 112. １ As it approaches, the differential pressure ΔP becomes the first pressure difference ΔP １ The above is the second pressure difference ΔP ２ The second valve 19 is closed when the range falls below the specified limit.

[0036] As described above, in the battery pack 10 of this embodiment, the first valve 18 and the second valve 19 open and close in response to the rise and fall in temperature of the battery 12 due to the operation of the vehicle 1, allowing for the exchange of gas between the first chamber 111 and the second chamber 112, and enabling the dehumidified dry gas from the second chamber 112 to be circulated to the first chamber 111.

[0037] [Effects of this embodiment] The battery pack 10 of this embodiment includes a case 11 for housing a battery 12. The case 11 includes a first chamber 111 in which the battery 12 is housed, a second chamber 112 adjacent to the first chamber 111, and a partition wall 113 separating the first chamber 111 and the second chamber 112. The second chamber 112 is connected to a refrigerant pipe 3 that also functions as a dehumidification mechanism for dehumidifying the inside of the second chamber 112. The second chamber 112 is also provided with a pressure adjustment section 17, which consists of a communication section 171 communicating with the outside of the case 11 and a hydrophobic permeable membrane 172 that closes the communication section 171 and allows only gas to pass through. The partition wall 113 is also provided with a first valve 18 and a second valve 19. The first valve 18 controls the pressure P of the second chamber 112. ２ Pressure P from the first room 111 １ The differential pressure ΔP obtained by subtracting the first pressure difference ΔP is the first pressure difference ΔP. １When the pressure difference ΔP is less than the first pressure difference ΔP, it opens and gas flows from the first chamber 111 to the second chamber 112. １ The valve is closed if the above conditions are met. The second valve 19 closes when the differential pressure ΔP is equal to the second pressure difference ΔP ２ When the pressure exceeds the second pressure difference ΔP, it opens and gas flows from the second chamber 112 to the first chamber 111. ２ It will be blocked in the following cases:

[0038] In this embodiment of the battery pack 10, the second chamber 112 is maintained at a constant pressure by the pressure adjustment unit 17. Therefore, as the temperature of the battery 12 changes, the pressure in the first chamber 111 changes, creating a differential pressure ΔP between the first chamber 111 and the second chamber 112. This differential pressure ΔP is then used as the first pressure difference ΔP. １ If the value is less than the second pressure difference ΔP, the first valve 18 is opened, and the differential pressure ΔP becomes the second pressure difference ΔP. ２ When the temperature exceeds a certain level, the second valve 19 is opened. This causes gas to circulate between the first chamber 111 and the second chamber 112. Since the refrigerant piping 3, which functions as a dehumidification mechanism, is in contact with the second chamber 112, dry gas is introduced into the first chamber 111 where the battery 12 is housed through the circulation of gas as described above. In this embodiment, for example, components such as an air-cooling fan, a cooling device dedicated to cooling the battery, and sensors for measuring temperature and humidity become unnecessary, and a system configuration for controlling these components also becomes unnecessary, thus simplifying the configuration of the battery pack 10.

[0039] In the battery pack 10 of this embodiment, the first valve 18 is activated by the pressure increase in the first chamber 111 due to the rise in temperature of the battery 12 caused by the operation of the vehicle 1, so that the differential pressure ΔP becomes the first pressure difference ΔP １ It opens when the pressure drops below a certain level. Also, the second valve 19 opens when the pressure in the first chamber 111 decreases as the temperature of the battery 12 decreases after the temperature of the battery 12 rises, and the differential pressure ΔP becomes the second pressure difference ΔP ２It is opened when the temperature exceeds a certain level. In other words, in this embodiment, the first valve 18 and the second valve 19 are opened and closed alternately by the rise and fall of the battery 12 temperature associated with the operation of the vehicle 1, allowing the gas to circulate between the first chamber 111 and the second chamber 112. This eliminates the need for a separate configuration such as a fan to circulate the gas between the first chamber 111 and the second chamber 112.

[0040] In the battery pack 10 of this embodiment, the first valve 18 is located at the center position Z in the height direction of the partition wall 113. Ｃ Rather, it is located on the bottom surface 11D side of the second chamber 112. This allows corrosive and acidic gases that are heavier than air to be preferentially discharged from the first chamber 111 to the second chamber 112, thereby suppressing the deterioration of the battery 12, the junction box connected to the battery 12, and the battery management system due to corrosive and acidic gases.

[0041] In the battery pack 10 of this embodiment, the second valve 19 is located at the center position Z in the height direction of the partition wall 113. Ｃ Rather, it is positioned on the top surface 11U side of the second room 112. This prevents condensation water generated in the second room 112 from flowing into the first room 111 due to the acceleration or tilting of the vehicle 1 during vehicle operation. It also prevents corrosive gases and acidic gases that are heavier than air from flowing from the second room 112 to the first room 111.

[0042] In this embodiment, the battery pack 10 is equipped with a refrigerant pipe 3 that is in contact with the second chamber 112, and the refrigerant pipe 3 functions as a dehumidification mechanism. By utilizing the refrigerant pipe 3 used in the cooling mechanism 2 of the vehicle 1, there is no need to provide a separate dehumidification mechanism dedicated to the battery pack 10, thus simplifying the configuration. Furthermore, the refrigerant pipe 3 can perform both dehumidification and cooling of the second chamber 112. That is, dehumidified and cooled gas can be flowed from the second valve 19 to the first chamber 111.

[0043] In the battery pack 10 of this embodiment, the second chamber 112 is located on the front Fr side of the vehicle 1 than the first chamber 111, and a cooling mechanism 2 to which refrigerant piping 3 is connected is provided on the front Fr side of the vehicle 1. This makes it possible to shorten the refrigerant piping 3 extending from the cooling mechanism 2 to the second chamber 112, thereby simplifying the configuration.

[0044] In the battery pack 10 of this embodiment, the second chamber 112 is provided with a drain section 16 for removing water droplets generated by cooling by the refrigerant piping 3. This allows water droplets generated by condensation due to cooling by the refrigerant piping 3 to be removed (discharged) from the drain section 16, thereby keeping the humidity in the second chamber 112 low.

[0045] In the battery pack 10 of this embodiment, the bottom surface of the second chamber 112 is provided with an inclined surface 15 that slopes from top to bottom, and the drainage section 16 is provided at the lower end 151 of the inclined surface 15. As a result, water droplets generated in the second chamber 112 by cooling by the refrigerant piping 3 can be collected in the drainage section 16 using the inclined surface 15, and the water can be efficiently drained.

[0046] In the battery pack 10 of this embodiment, the drain section 16 includes a storage section 161 for storing water, and a discharge section (discharge passage 162, discharge valve 163, and biasing member 164) for discharging the stored water when a predetermined amount of water is stored in the storage section 161. As a result, when the amount of stored water exceeds a predetermined amount, the discharge valve 163 is opened, allowing the water stored in the storage section 161 to be discharged from the discharge passage 162. Furthermore, when the discharge valve 163 is closed, it is possible to suppress the backflow of water from the discharge passage 162 to the storage section 161 and the entry of water from outside the case 11 into the second chamber 112.

[0047] In the battery pack 10 of this embodiment, the first chamber 111 is provided with a PRD 13 that releases the gas from the first chamber 111 to the outside of the case 11. This PRD 13 is configured such that the differential pressure ΔP is equal to the first pressure difference ΔP １ A third pressure difference ΔP is smaller than this. ３ It is released when it falls below a certain value. In other words, the pressure P in the first chamber 111 １ The pressure outside case 11 is greater than |ΔP１ When the pressure exceeds |, the first valve 18 opens, and the pressure P １ As it increases, |ΔP| becomes greater than the pressure outside case 11. ３ When the volume exceeds the limit, the PRD 13 is opened. By providing such a PRD 13, if abnormal heat generation occurs in the battery cells of the battery 12, the gas in the first chamber 111 can be urgently discharged.

[0048] [Modifications] The present invention is not limited to the embodiments described above, but also includes the following modifications to the extent that the objectives of the present invention can be achieved.

[0049] [Modification 1] In the above embodiment, a refrigerant pipe 3 in contact with the second chamber 112 was exemplified as the dehumidification mechanism in this disclosure, but it is not limited thereto. Figure 6 is a diagram showing an example of a dehumidification mechanism for the second chamber 112 in another embodiment. In the battery pack 10A shown in Figure 6, a dehumidifying material 4 is placed in the second chamber 112 as a dehumidification mechanism. The dehumidifying material 4 is a chemically stable material that does not affect the battery 12, such as silica gel or molecular sieve. When using a dehumidifying material 4, for example, as shown in Figure 6, an openable and closable pocket 112A is provided in the second chamber 112, and the dehumidifying material 4 is placed inside the pocket 112A. The pocket 112A in Figure 6 is provided, for example, on the front part 11F, and can be opened outwards to replace the dehumidifying material 4, and can be closed to seal it airtight.

[0050] Alternatively, after arranging the moisture-absorbing material 4, a configuration may be provided in which refrigerant piping 3 is in contact with the second chamber 112, as in the embodiment described above. In this case, dehumidification can be performed by the moisture-absorbing material 4, and cooling and dehumidification can be performed by the refrigerant piping 3, thereby further enhancing the dehumidification effect.

[0051] [Modification 2] In the above embodiment, an example was shown in which the second chamber 112 is located on the front Fr side of the vehicle 1 than the first chamber 111, but the vehicle is not limited to this. In a typical vehicle, the drive mechanism such as the engine is located on the front side, and the cooling mechanism 2 is installed behind the front grille on the front side where it is easy to take in outside air while driving. However, in a vehicle in which the drive mechanism such as the engine is located on the rear side, the cooling mechanism 2 may be provided on the rear side. When the battery pack 10 of this disclosure is installed in such a vehicle, the second chamber 112 may be located on the rear side than the first chamber 111. This makes it possible to shorten the length of the refrigerant piping 3 when extending the refrigerant piping 3 connected to the cooling mechanism 2 into the second chamber 112.

[0052] Furthermore, if multiple components to be cooled are arranged on the front and rear sides of the vehicle, a cooling mechanism 2 may be provided on both the front and rear sides. In this case, the second chamber 112 should be positioned close to the cooling mechanism 2 closest to the battery pack 10.

[0053] [Modification 3] In the above embodiment, an example was shown in which the inclined surface 15 is inclined to the -Z side as it moves from the front portion 11F toward the -X side. However, a configuration in which the inclined surface 15 is inclined to the -Z side as it moves toward the front portion 11F side is also possible. In this case, the water generated by condensation flows toward the side away from the first room 111, so the inconvenience of the water entering the first room 111 can be further suppressed.

[0054] 1...Vehicle, 2...Cooling mechanism, 3...Refrigerant piping (also functions as a dehumidification mechanism), 4...Moisture absorbent material (dehumidification mechanism), 10, 10A...Battery pack, 11...Case, 12...Battery, 15, 15A, 15B...Inclined surface, 16...Water drain section, 17...Pressure adjustment section, 18...First valve, 19...Second valve, 111...First chamber, 112...Second chamber, 113...Bulkhead, 151...Lower end, 161...Storage section, 162...Discharge passage, 163...Discharge valve, 164...Biasing member, 171...Communication section, 172...Permeable membrane, Fr...Front, R...Rear.

Claims

A battery pack that includes a case for housing a battery and is mounted on a vehicle, The case comprises a first room in which the battery is housed, a second room adjacent to the first room, and a partition separating the first room and the second room. The second chamber comprises a dehumidification mechanism for dehumidifying the inside of the second chamber, a communication section connecting the second chamber and the outside of the case, and a hydrophobic permeable membrane that closes the communication section and allows only gas to pass through. The aforementioned partition wall has, A first valve is opened when the pressure difference obtained by subtracting the pressure in the first chamber from the pressure in the second chamber is less than a predetermined first pressure difference, and is closed when it is equal to or greater than the first pressure difference. A battery pack is provided with a second valve that is opened when the pressure difference obtained by subtracting the pressure of the first chamber from the pressure of the second chamber exceeds a predetermined second pressure difference, and closed when it is less than or equal to the second pressure difference. 　 The first valve is opened when the differential pressure becomes less than the first pressure difference due to the pressure increase in the first chamber caused by the rise in battery temperature due to the operation of the vehicle. The second valve is opened when, after the battery temperature rises, the pressure in the first chamber decreases due to the decrease in pressure resulting from the decrease in the battery temperature, causing the differential pressure to exceed the second pressure difference. The battery pack according to claim 1. 　 The first valve is positioned on the bottom side of the second chamber, relative to the center of the partition wall in the height direction. The battery pack according to claim 1. 　 The second valve is positioned on the upper side of the second chamber, relative to the center of the partition wall in the height direction. The battery pack according to claim 1. 　 The dehumidification mechanism is provided adjacent to the second chamber and is a refrigerant piping through which a refrigerant flows. The battery pack according to claim 1. 　 The second room is located further forward of the vehicle than the first room, and a cooling mechanism to which the refrigerant piping is connected is provided on the front side of the vehicle. The battery pack according to claim 5. 　 The second chamber is equipped with a drain section for removing water droplets generated by cooling by the refrigerant piping. The battery pack according to claim 6. 　 The bottom surface of the second room is provided with an inclined surface that slopes downward from above. The drainage section is provided at the lower end of the inclined surface. The battery pack according to claim 7. 　 The drain section includes a storage section for storing water and a discharge section for discharging the stored water once a predetermined amount of water has been stored in the storage section. The battery pack according to claim 7. 　 The dehumidification mechanism is a desiccant placed in the second chamber. The battery pack according to claim 1. 　 The first chamber is provided with a safety valve that releases the gas from the first chamber to the outside of the case. The safety valve is opened when the pressure difference obtained by subtracting the pressure in the first chamber from the pressure in the second chamber becomes less than a third pressure difference, which is smaller than the first pressure difference. The battery pack according to claim 1.

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