Battery system

Abstract

To provide a battery system for an air vehicle.SOLUTION: A battery system 10 for an aircraft includes a battery pack (100) and an airtight battery case (200) for housing the battery pack, and the compressive fracture strength of the battery case is smaller than the pressure corresponding to the pressure difference between the atmospheric pressure at the aircraft's highest flight altitude and the atmospheric pressure at the aircraft's lowest altitude, and the battery case has a first pressure regulating valve (210) that introduces gas outside the battery case into the battery case to adjust the case pressure difference, which is the pressure difference between the atmospheric pressure outside the battery case and the atmospheric pressure inside the battery case, such that the case pressure difference is smaller than the compressive fracture strength, and the first pressure regulating valve is configured not to open from the time the aircraft takes off until it reaches the highest flight altitude and drops from the highest flight altitude to a predetermined first altitude, and to open at an altitude lower than the first altitude.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery system. [Background technology]

[0002] Patent Document 1 describes "a battery pack for a vehicle, the battery pack including: a thin fire box for enclosing the battery and containing thermal runaway gas; thermal insulation surrounding the fire box; a vent extending through the fire box and the thermal insulation to the exterior of the vehicle; a vent plug; and a pressure relief outlet frangible cover at least partially covering the vent plug and retaining the vent plug within the vent." [Prior art document] [Patent documents] [Patent Document 1] Special Publication No. 2022-529539 Summary of the Invention [Means for solving the problem]

[0003] According to one embodiment of the present invention, there is provided a battery system. The battery system may be for use in an aircraft. The battery system may include a battery pack and an airtight battery case that houses the battery pack. The compressive fracture strength of the battery case may be equal to or less than a pressure corresponding to a pressure difference between the atmospheric pressure at the aircraft's maximum flight altitude and the atmospheric pressure at the aircraft's minimum flight altitude. The battery case may include a first pressure regulation valve that adjusts the case pressure difference, which is the pressure difference between the atmospheric pressure outside the battery case and the atmospheric pressure inside the battery case, by introducing gas outside the battery case into the battery case so that the case pressure difference is smaller than the compressive fracture strength. The first pressure regulation valve is configured to remain closed from the time the aircraft takes off until it reaches the maximum flight altitude and descends from the maximum flight altitude to a predetermined first altitude, and to open at an altitude lower than the first altitude.

[0004] In the battery system, the expansion and fracture strength of the battery case may be greater than a pressure corresponding to a pressure difference between the atmospheric pressure at the highest flight altitude and the atmospheric pressure at the lowest flight altitude.

[0005] In the battery system, the battery case may further include a second pressure regulating valve that releases gas inside the battery case to the outside of the battery case to adjust the case pressure difference so that the expansion and deformation of the battery case due to the case pressure difference does not exceed a predetermined deformation range.

[0006] In the battery system, the expansion and rupture strength of the battery case may be equal to or less than the pressure corresponding to the pressure difference between the air pressure at the highest flight altitude and the air pressure at the lowest altitude, and the battery case may further include a second pressure regulating valve that adjusts the case pressure difference by releasing gas inside the battery case to the outside of the battery case so that the case pressure difference is smaller than the expansion and rupture strength, and is configured to not open while the flight altitude of the aircraft is equal to or greater than the first altitude and to open at altitudes lower than the first altitude.

[0007] In any of the battery systems described above, the first altitude may be determined by the ozone concentration at each altitude.

[0008] In any of the battery systems described above, the first altitude may be a minimum flight altitude during a period in which the flying object continues to fly in the air.

[0009] In any of the battery systems described above, the first pressure regulation valve may be configured to open in response to the case pressure differential exceeding a first pressure threshold within a predetermined first pressure threshold range, and the first pressure threshold range may include 20 kPa. The first pressure threshold may be 20 kPa. The first pressure threshold may be 15 kPa.

[0010] In any of the battery systems described above, the maximum flight altitude may be a stratospheric altitude.

[0011] In any of the battery systems described above, the first pressure regulating valve may include a valve portion and an elastic portion, the elastic portion may be configured to press the valve portion to close the valve portion, the first pressure regulating valve may be made of plastic, or the portion of the first pressure regulating valve excluding the elastic portion may be made of plastic. The aircraft may fly in the stratosphere, and the pressing force applied to the valve portion by the elastic portion of the first pressure regulating valve may be configured to prevent the valve from opening while the aircraft is flying in the stratosphere.

[0012] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows a schematic diagram of an example of a battery system 10. [Figure 2] 2 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 and a battery system 10. FIG. [Figure 3] 1 shows a schematic diagram of an example of a battery system 10. [Figure 4] 2 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 and a battery system 10. FIG. [Figure 5] 1 shows a schematic diagram of an example of a battery system 10. [Figure 6] 2 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 and a battery system 10. FIG. [Figure 7] An example of a pressure regulator valve 210 is shown schematically. [Figure 8] An example of a pressure regulator valve 220 is shown schematically. [Figure 9] 10 is an explanatory diagram for explaining the adjustment of the pressure at which the pressure regulating valve 210 opens. FIG. [Figure 10] 1 shows a schematic diagram of an example of a battery system 10. [Figure 11]An example of a High Altitude Platform Station (HAPS) 700 equipped with a battery system 10 is shown schematically. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0015] In conventional battery system operating environments, measures such as sealing the battery case housing the battery pack were not necessary. However, when a battery system is installed on an aircraft flying at high altitudes, such as the stratosphere, it is necessary to configure the battery system so that it can operate normally and have the necessary durability, even in extremely low temperature environments (approximately -90°C to -60°C), extremely low atmospheric pressure environments (approximately 0.03 to 0.25 kPa), and high ozone concentrations (approximately 10 ppm). Therefore, when rubber or resin is used as a component of the battery pack, measures such as making the battery system airtight are necessary to prevent ozone degradation of the components. In this case, it is possible to increase the breaking strength of the battery system so that it can withstand a pressure of approximately 100 kPa, which is the pressure difference between ground pressure and high-altitude pressure. However, increasing the breaking strength requires, for example, increasing the thickness of the battery system's structural components, which increases the weight of the battery system and the energy consumption of the aircraft.

[0016] The battery system 10 according to this embodiment has a configuration that contributes to solving these problems. For example, in the battery system 10, the battery pack is housed in an airtight battery case, and a pressure regulating valve is installed in the battery case to adjust the pressure inside the battery case by, for example, letting gas in and out between the inside and outside of the battery case. This prevents the battery case from being destroyed by a difference in air pressure. Since the destruction strength required of the battery case can be reduced, a reduction in the weight of the battery system can also be expected. Furthermore, for example, by appropriately adjusting the altitude at which the pressure regulating valve opens and closes, the intrusion of ozone gas into the battery case can be suppressed.

[0017] FIG. 1 shows a schematic diagram of an example of a battery system 10. The battery system 10 includes a battery pack 100 and an airtight battery case 200. The battery system 10 may be for an aircraft. The battery pack 100 may be any type of battery. For example, the battery pack 100 may be a lithium metal battery. The battery case 200 may be made of metal. The battery case 200 may be made of aluminum. The battery case 200 may be an aluminum laminate structure.

[0018] The battery case 200 may be box-shaped. In the example shown in FIG. 1 , the battery case 200 is a rectangular parallelepiped and has a rectangular cross-sectional shape, but the shape of the battery case 200 is not limited thereto. For example, the battery case 200 may be spherical, and the cross-sectional shape of the battery case 200 may be circular. There may be a space between the battery pack 100 and the battery case 200. The battery pack 100 may be arranged so as to be located in a predetermined space within the battery case 200.

[0019] The airtightness of the battery case 200 may be such that it prevents gas from entering or exiting between the inside and outside of the battery case 200. The airtightness of the battery case 200 may be such that it suppresses the gas from entering or exiting between the inside and outside of the battery case 200, and it does not have to be such that it prevents the gas from entering or exiting.

[0020] FIG. 2 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 equipped with the battery system 10 illustrated in FIG. 1 and the state of the battery system 10. The upper half of FIG. 2 shows the change in altitude of the aircraft 70 from takeoff to landing, and the change in air pressure at each altitude where the aircraft 70 is located. In this example, after takeoff and ascending, the aircraft 70 flies in a predetermined altitude range for a predetermined period of time, and then descends and lands. The predetermined altitude range may be the stratosphere. The predetermined altitude range may be determined appropriately taking into consideration the flight capability of the aircraft 70, the stratospheric environment, and the like. For example, the predetermined altitude range may be an altitude range of 12,000 m to 25,000 m. For example, the predetermined altitude range may be an altitude range of 16,000 m to 25,000 m in the stratosphere. The predetermined period is not particularly limited and may be, for example, less than six months, more than six months, less than one year, or more than one year.

[0021] The altitude and air pressure at the time of takeoff of the aircraft 70 may be referred to as the takeoff altitude and takeoff air pressure, respectively. The altitude and air pressure at the time of landing of the aircraft 70 may be referred to as the landing altitude and takeoff air pressure, respectively. The takeoff altitude may be an example of the minimum altitude H1, and the takeoff air pressure may be an example of the air pressure P1 at the minimum altitude H1. The landing altitude may be an example of the minimum altitude H1, and the landing air pressure may be an example of the air pressure P1 at the minimum altitude H1. The takeoff altitude and the landing altitude may be the same altitude, or may be different altitudes. For example, if the takeoff point and landing point of the aircraft 70 are different, the takeoff altitude and the landing altitude may be different altitudes. In the example shown in FIG. 2, the takeoff altitude and the landing altitude are the same altitude, and the takeoff air pressure and the landing air pressure are the same air pressure.

[0022] The maximum flight altitude H3 is the highest altitude that the aircraft 70 reaches during the period from takeoff to landing. The maximum flight altitude H3 may be an altitude in the stratosphere. In the example shown in FIG. 2, the maximum flight altitude H3 is an altitude in the stratosphere. The minimum flight altitude H2 is the lowest altitude that the aircraft 70 reaches during a predetermined period of time that the aircraft 70 is airborne. In the example shown in FIG. 2, the air pressure at the maximum flight altitude H3 is indicated as P3, and the air pressure at the minimum flight altitude H2 is indicated as P2.

[0023] As the flying object 70 ascends, the external pressure of the battery case 200 decreases as the flying object 70 ascends. However, because the battery case 200 is airtight, the internal pressure of the battery case 200 maintains the internal pressure before the start of the ascent. For example, when the flying object 70 ascends from the minimum altitude H1 to the maximum flight altitude H3, the external pressure of the battery case 200 decreases from the pressure P1 at the minimum altitude H1 to the pressure P3 at the maximum flight altitude H3, but the internal pressure of the battery case 200 maintains the pressure P1 at the minimum altitude H1. This causes a pressure difference between the inside and outside of the battery case 200. The pressure difference between the external pressure of the battery case 200 and the internal pressure of the battery case 200 is sometimes referred to as the case pressure difference. In the above case, the case pressure difference is P1 - P3.

[0024] The battery case 200 is subjected to pressure corresponding to the case pressure difference from the inside of the battery case 200 to the outside of the battery case 200, causing the battery case 200 to expand and deform. If the expansion-to-fracture strength, which is the strength at which the battery case 200 is broken due to expansion, is greater than the case pressure difference, the battery case 200 does not expand to fracture. If the expansion-to-fracture strength of the battery case 200 is smaller than the case pressure difference, the battery case 200 expands to fracture.

[0025] Although the battery case 200 is airtight, the case pressure difference continues to be experienced during a predetermined period of flight of the flying object 70, which may cause the gas inside the battery case 200 to slowly leak out of the battery case 200. For example, when the amount of gas leakage is at its highest, the internal air pressure of the battery case 200 becomes equal to the external air pressure, and the case pressure difference becomes zero.

[0026] As the flying object 70 descends, the external pressure of the battery case 200 increases as the flying object 70 descends. However, because the battery case 200 is airtight, the internal pressure of the battery case 200 maintains the same internal pressure as before the descent began. For example, during a predetermined period of flight, the internal and external pressures of the battery case 200 may become equal, and the case pressure difference may become zero. After this, the flying object 70 may descend from the maximum flight altitude H3 to the minimum altitude H1. In this case, the external pressure of the battery case 200 increases from pressure P3 at the maximum flight altitude H3 to pressure P1 at the minimum altitude H1, but the internal pressure of the battery case 200 maintains pressure P3 at the maximum flight altitude H3. This results in a case pressure difference P1-P3.

[0027] The battery case 200 is subjected to a pressure corresponding to the case pressure difference from the outside of the battery case 200 toward the inside of the battery case 200, causing the battery case 200 to undergo compressive deformation. If the compressive fracture strength of the battery case 200, which is the strength at which the battery case 200 breaks due to compression, is greater than the case pressure difference, the battery case 200 does not break due to compression. If the compressive fracture strength of the battery case 200 is equal to or less than the case pressure difference, the battery case 200 breaks due to compression.

[0028] Condition A in FIG. 2 shows a change in the state of the battery system 10 when the expansion-to-rupture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the aircraft's highest flight altitude H3 and the air pressure P1 at the aircraft's lowest altitude H1, and gas inside the battery case 200 does not leak out of the battery case 200 during a predetermined period of flight of the aircraft 70. In the example shown in condition A, the battery case 200 expands and deforms as the aircraft 70 takes off and ascends, but does not expand to rupture. Furthermore, during the predetermined period of flight of the aircraft 70, gas inside the battery case 200 does not leak out of the battery case 200, and the internal air pressure at takeoff is maintained. Therefore, even if the external air pressure of the battery case 200 increases as the aircraft 70 descends, the internal air pressure of the battery case 200 remains greater than the external air pressure of the battery case 200, and the battery case 200 does not undergo compressive deformation. As the altitude of the flying object 70 decreases, the case pressure difference decreases, and when the altitude of the flying object 70 reaches the lowest altitude H1, the case pressure difference becomes zero.

[0029] 2 shows a change in the state of the battery system 10 when the expansion fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the highest flight altitude H3 of the flying object 70 and the air pressure P1 at the lowest altitude H1 of the flying object 70, and the compression fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the highest flight altitude H3 of the flying object 70 and the air pressure P1 at the lowest altitude H1 of the flying object 70, and gas inside the battery case 200 leaks out of the battery case 200 during a predetermined period of flight of the flying object 70. In the example shown in condition B, the battery case 200 undergoes expansion and deformation as the flying object 70 takes off and ascends, but does not undergo expansion and fracture. Furthermore, during a predetermined period of time that the flying object 70 is in the air, the gas inside the battery case 200 leaks out to the outside of the battery case 200, the internal air pressure of the battery case 200 becomes equal to the external air pressure, and the case pressure difference becomes zero. Furthermore, as the flying object 70 descends and lands, the battery case 200 undergoes compressive deformation but does not undergo compressive destruction.

[0030] 2 shows a change in the state of the battery system 10 when the expansion fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the flying object 70 and the air pressure P1 at the minimum altitude H1 of the flying object 70, the compression fracture strength of the battery case 200 is equal to or less than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the flying object 70 and the air pressure P1 at the minimum altitude H1 of the flying object 70, and gas inside the battery case 200 leaks out of the battery case 200 during a predetermined period of flight of the flying object 70. In the example shown in condition C, the battery case 200 undergoes expansion and deformation as the flying object 70 takes off and ascends, but does not undergo expansion and fracture. Furthermore, during a predetermined period of time that the flying object 70 is flying in the air, the gas inside the battery case 200 leaks out to the outside of the battery case 200, the internal air pressure of the battery case 200 becomes equal to the external air pressure, and the case pressure difference becomes zero. Furthermore, as the flying object 70 descends and lands, the battery case 200 undergoes compressive deformation, and at an altitude where the case pressure difference becomes equal to the compressive fracture strength of the battery case 200, the battery case 200 undergoes compressive fracture.

[0031] FIG. 3 schematically illustrates an example of a battery system 10. In FIG. 3, differences from the example illustrated in FIG. 1 will be mainly described, and common parts will not be described. In the example illustrated in FIG. 3, the battery system 10 includes a pressure regulating valve 210. The pressure regulating valve 210 adjusts the case pressure difference by introducing gas outside the battery case 200 into the battery case 200 so that the case pressure difference is smaller than the compressive fracture strength of the battery case 200. The pressure regulating valve 210 may be a check valve. In the example illustrated in FIG. 3, the pressure regulating valve 210 is installed so as to be located on the side of the battery case 200, but this is not a limitation. The pressure regulating valve 210 may be located anywhere in the battery case 200 as long as it is possible to adjust the case pressure difference. The pressure regulating valve 210 may be an example of a first pressure regulating valve.

[0032] FIG. 4 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 equipped with the battery system 10 illustrated in FIG. 3 and the state of the battery system 10. In FIG. 4, differences from the example illustrated in FIG. 2 are mainly described, and commonalities with the example illustrated in FIG. 2 are not described. The right half of the upper half of FIG. 4 shows an example of the relationship between altitude and air pressure and the relationship between altitude and ozone concentration, superimposed on each other. Air pressure is approximately 100 kPa at altitudes near the ground and decreases with increasing altitude. The decrease in air pressure with each altitude is greater at lower altitudes and smaller at higher altitudes. Ozone concentrations are relatively low in the troposphere, but increase with increasing altitude up to an altitude of 25,000 m in the stratosphere.

[0033] In the example shown in Fig. 4, the battery system 10 has a pressure regulating valve 210. Condition D in Fig. 4 shows a change in the state of the battery system 10 when the expansion fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the aircraft 70 and the air pressure P1 at the minimum altitude H1 of the aircraft 70, the compression fracture strength of the battery case 200 is equal to or less than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the aircraft 70 and the air pressure P1 at the minimum altitude H1 of the aircraft 70, and gas inside the battery case 200 leaks out of the battery case 200 during a predetermined period of flight of the aircraft 70. In the example shown in condition D, the battery case 200 undergoes expansion and deformation as the aircraft 70 takes off and ascends, but does not undergo expansion and fracture. Furthermore, during a predetermined period during which the flying object 70 is in the air, gas inside the battery case 200 leaks out to the outside of the battery case 200, causing the internal and external pressures of the battery case 200 to become equal, resulting in a zero case pressure difference. During the predetermined period during which the flying object 70 is in the air, the pressure regulating valve 210 opens in response to changes in air pressure accompanying changes in the altitude of the flying object 70, allowing gas outside the battery case 200 to enter the battery case 200 and adjusting the case pressure difference. This prevents the battery case 200 from collapsing due to compression. In other words, the situation shown in condition C in FIG. 2 can be prevented. In this case, because the pressure regulating valve 210 opens at altitudes where the ozone concentration is high, ozone may enter the battery case 200, potentially causing deterioration of rubber or plastic components. In FIG. 4, the areas of the battery case 200 where ozone has entered are indicated by diagonal lines.

[0034] 4 shows a change in the state of the battery system 10 when the expansion fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the flying object 70 and the air pressure P1 at the minimum altitude H1 of the flying object 70, the compression fracture strength of the battery case 200 is equal to or less than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the maximum flight altitude H3 of the flying object 70 and the air pressure P1 at the minimum altitude H1 of the flying object 70, and gas inside the battery case 200 leaks out of the battery case 200 during a predetermined period of flight of the flying object 70. In the example shown in condition E, the battery case 200 undergoes expansion and deformation as the flying object 70 takes off and ascends, but does not undergo expansion and fracture. Furthermore, during a predetermined period during which the flying object 70 is in flight, gas inside the battery case 200 leaks out to the outside of the battery case 200, causing the internal and external pressures of the battery case 200 to become equal, and the case pressure difference to become zero. In the example shown in condition E of FIG. 4, the pressure regulating valve 210 is configured not to open from the time the flying object 70 takes off until it reaches its maximum flight altitude H3 and descends from the maximum flight altitude H3 to a predetermined altitude, but to open at an altitude lower than the predetermined altitude. The predetermined altitude may be an example of a first altitude. This prevents compression damage to the battery case 200. In other words, it prevents the situation shown in condition C of FIG. 2 from occurring. The predetermined altitude may be an altitude determined based on the ozone concentration at each altitude. This prevents ozone gas from entering the battery case 200. In other words, it prevents ozone from entering the battery case 200 during flight and landing, as in condition D of FIG. 4. The predetermined altitude may be an altitude at which the ozone concentration begins to increase. The predetermined altitude may be an altitude at which the ozone concentration exceeds one concentration threshold within a predetermined concentration threshold range. The predetermined altitude may be an altitude representing the boundary between the stratosphere and the troposphere. The predetermined altitude may be, for example, 11,000 m. The predetermined altitude may be the lowest flight altitude H2 during the period in which the flying object 70 continues to fly. The predetermined altitude may be, for example, 16,000 m. The predetermined altitude may be, for example, 12,000 m.This makes it possible to prevent ozone from entering the battery case 200 at least during the period when the flying object 70 is flying in the air, and even if ozone does enter the battery case 200, it can be prevented from entering during the short period when the flying object 70 is descending.

[0035] Condition F in Fig. 4 shows a change in the state of the battery system 10 when the expansion and fracture strength of the battery case 200 is equal to or less than the pressure corresponding to the pressure difference P1-P3 between the air pressure P3 at the highest flight altitude H3 of the flying object 70 and the air pressure P1 at the lowest altitude H1 of the flying object 70. In the example shown in condition F, the battery case 200 expands and deforms as the flying object 70 takes off and ascends, and the battery case 200 expands and fractures at an altitude where the case pressure difference becomes equal to the expansion and fracture strength of the battery case 200. In this case, the airtightness of the battery case 200 is lost at altitudes where the ozone concentration is high, and ozone may enter the battery case 200, causing deterioration of rubber or plastic components.

[0036] FIG. 5 schematically illustrates an example of a battery system 10. In FIG. 5, differences from the example illustrated in FIG. 3 will be mainly described, and common parts will not be described. In the example illustrated in FIG. 5, the battery system 10 further includes a pressure regulating valve 220. The pressure regulating valve 220 may adjust the case pressure difference by releasing gas inside the battery case 200 to the outside of the battery case 200 so that the case pressure difference is smaller than the expansion fracture strength of the battery case 200. The pressure regulating valve 220 may be a check valve. Like the pressure regulating valve 210, the position of the pressure regulating valve 220 is not limited to the side surface of the battery case 200. The position of the pressure regulating valve 220 may be anywhere in the battery case 200 as long as it is possible to adjust the case pressure difference.

[0037] In the example shown in FIG. 5 , the pressure regulation valve 220 has the same configuration as the pressure regulation valve 210, but is installed facing in the opposite direction to the pressure regulation valve 210. However, this is not limited to this. The pressure regulation valve 210 and the pressure regulation valve 220 may have different configurations. In the example shown in FIG. 5 , the pressure regulation valve 210 and the pressure regulation valve 220 are arranged side by side on the side of the battery case 200, but this is not limited to this. For example, the pressure regulation valve 210 and the pressure regulation valve 220 may be arranged on different sides of the battery case 200. The pressure regulation valve 210 and the pressure regulation valve 220 may be arranged on different opposing sides of the battery case 200. The pressure regulation valve 210 and the pressure regulation valve 220 may be arranged on opposing side surfaces of the battery case 200.

[0038] Figure 6 is an explanatory diagram illustrating the relationship between the altitude of an aircraft 70 equipped with the battery system 10 illustrated in Figure 5 and the state of the battery system 10. In Figure 6, differences from the example illustrated in Figure 4 will be mainly described, and parts common to the example illustrated in Figure 4 will not be described. In the example illustrated in Figure 4, the battery system 10 further includes a pressure regulating valve 220.

[0039] Condition G in FIG. 6 illustrates a change in the state of the battery system 10 when the expansion and fracture strength of the battery case 200 is greater than the pressure corresponding to the pressure difference P1-P3 between the atmospheric pressure P3 at the aircraft 70's highest flight altitude H3 and the atmospheric pressure P1 at the aircraft 70's lowest altitude H1, and the pressure regulating valve 220 is configured to release gas from the battery case 200 to the outside of the battery case to adjust the case pressure difference so that the expansion and deformation of the battery case 200 due to the case pressure difference does not exceed a predetermined deformation range. The pressure regulating valve 220 may be an example of a second pressure regulating valve. In the example illustrated by condition G, the pressure regulating valve 220 can limit the expansion and deformation of the battery case 200 to a certain range. Therefore, for example, when the space for installing the battery system 10 within the aircraft 70 is limited, interference between the battery case 200 and the structural frame of the aircraft 70 or other battery systems 10 arranged adjacent to the battery case 200 can be prevented.

[0040] Condition H in FIG. 6 illustrates a change in the state of the battery system 10 when the expansion and rupture strength of the battery case 200 is smaller than the pressure corresponding to the pressure difference P1-P3 between the atmospheric pressure P3 at the highest flight altitude H3 of the flying object 70 and the atmospheric pressure P1 at the lowest flight altitude H1 of the flying object 70, and the pressure regulating valve 220 is configured to release gas from the battery case 200 to the outside of the battery case 200 to adjust the case pressure difference so that the case pressure difference is smaller than the expansion and rupture strength of the battery case 200. The pressure regulating valve 220 may be configured to remain closed while the flying object 70 is flying at a predetermined altitude or higher and to open at an altitude lower than the predetermined altitude. The pressure regulating valve 220 may be an example of a second pressure regulating valve. Specific examples of the predetermined altitude are the same as those in the example illustrated in condition E in FIG. 4. In the example illustrated in condition H, the pressure regulating valve 220 can prevent the battery case 200 from expanding and rupturing, thereby suppressing the intrusion of ozone gas into the battery case 200. In other words, the situation shown in the example of condition F in FIG. 4 can be prevented.

[0041] FIG. 7 schematically illustrates an example of a pressure regulation valve 210. The pressure regulation valve 210 may include a housing portion 212, a valve body portion 214, and an elastic body portion 216. The valve body portion 214 and the elastic body portion 216 may be disposed inside the housing portion 212. The elastic body portion 216 may be configured to close the valve by pressing the valve body portion 214. In the example illustrated in FIG. 7, the materials of the housing portion 212, the valve body portion 214, and the elastic body portion 216 are not particularly limited. For example, some or all of these portions may be made of metal. For example, some or all of these portions may be made of plastic or the like. In other words, the pressure regulation valve 210 may be made of plastic. The pressure regulation valve 210 may have portions other than the elastic body portion 216 made of plastic. This allows the battery system 10 to be lightweight, and ultimately allows the aircraft 70 to be lightweight. In the example illustrated in FIG. 7, the elastic body portion 216 is a metal spring, but is not limited thereto. The elastic portion 216 may be made of, for example, plastic. The elastic portion 216 may be made of, for example, a thermosetting elastomer such as rubber, or a thermoplastic elastomer. Here, "plastic" includes "thermosetting elastomer" and "thermoplastic elastomer." For example, the pressure at which the pressure regulation valve 210 opens can be adjusted by appropriately adjusting the elastic properties, such as the elastic modulus and strain-stress characteristics, of the elastic portion 216 and the area of ​​the opening of the pressure regulation valve 210. For example, the aircraft 70 may fly in the stratosphere, and the pressure applied by the elastic portion 216 of the pressure regulation valve 210 to the valve body portion 214 may be configured to prevent the valve from opening while the aircraft 70 is flying in the stratosphere. This prevents ozone gas from entering the battery case 200.

[0042] 8 schematically illustrates an example of a pressure regulating valve 220. The pressure regulating valve 220 may have a housing portion 222, a valve body portion 224, and an elastic body portion 226. The valve body portion 224 and the elastic body portion 226 may be disposed inside the housing portion 222. The elastic body portion 226 may be configured to close the valve by pressing the valve body portion 224. In the example illustrated in FIG. 8, similar to the case of the pressure regulating valve 210 illustrated in FIG. 7, the materials of the housing portion 222, the valve body portion 224, and the elastic body portion 226 are not particularly limited.

[0043] 9 is an explanatory diagram for explaining adjustment of the pressure at which the pressure regulation valve 210 opens. In the example shown in Fig. 9, for example, it may be desirable to adjust the pressure regulation valve 210 so that it does not open when the aircraft 70 is located at an altitude in the stratosphere, but opens when the aircraft 70 is located at an altitude lower than that of the stratosphere, i.e., when the aircraft 70 is located at an altitude in the troposphere. In this case, for example, the pressure difference between the air pressure P3 at the maximum flight altitude H3 of the aircraft 70 and the air pressure P4 at an altitude indicating the boundary between the stratosphere and the troposphere may be set as the pressure threshold Pv at which the pressure regulation valve 210 opens.

[0044] For example, based on the ozone concentration at each altitude, it may be desirable to adjust the pressure regulation valve 210 so that it does not open at altitudes higher than the altitude at which the ozone concentration begins to increase, but opens at altitudes lower than that altitude. Because the ozone concentration at each altitude varies depending on the region and season on Earth, the altitude at which the ozone concentration begins to increase also varies depending on the region and season on Earth. Therefore, a pressure threshold Pv at which the pressure regulation valve 210 opens may be set in advance within a pressure threshold range so that it can be selected depending on the region and time of year in which the flying vehicle 70 is actually operated. The valve may be configured to open when the case pressure difference exceeds one of the pressure thresholds within the predetermined pressure threshold range. This makes it possible to more effectively suppress ozone from entering the battery case 200 depending on the region and time of year in which the flying vehicle 70 is actually operated. In the example shown in FIG. 9, the pressure threshold range is set to include 20 kPa, and the pressure threshold Pv=20 kPa, so that the pressure regulating valve 210 can be adjusted so that it does not open at altitudes higher than the altitude at which the ozone concentration begins to increase.

[0045] 9, there may be a case where it is desired to adjust the pressure regulation valve 210 so that it does not open at altitudes higher than the minimum flight altitude H2 during the period in which the flying object 70 continues its airborne flight, but opens at altitudes lower than that altitude. In the example shown in Fig. 9, by setting the pressure threshold range to include 15 kPa and setting the pressure threshold Pv = 15 kPa, it is possible to adjust the pressure regulation valve 210 so that it does not open at altitudes higher than the minimum flight altitude H2 during the period in which the flying object 70 continues its airborne flight, but opens at altitudes lower than that altitude.

[0046] Fig. 10 schematically illustrates an example of a battery system 10. In Fig. 10, differences from the example illustrated in Fig. 5 will be mainly described, and common parts will not be described. In the example illustrated in Fig. 10, the battery system 10 includes a base plate 201, a sealing layer 202, a vent valve 203, a heat insulating layer 204, and a radiant heat reflecting layer 205.

[0047] The base plate 201 is a plate-shaped member and may be made of carbon fiber, fiberglass, a composite material of carbon fiber and fiberglass, or other lightweight materials. In the example shown in Fig. 10, the battery case 200 and the base plate 201 may be joined by a sealing layer 202 to form an airtight battery case 200 as a whole. The sealing layer 202 may be made by fusing plastic such as polyethylene or polypropylene.

[0048] The base plate 201 may have a vent valve 203. The vent valve 203 may release thermal runaway gases and the like that are generated to the outside of the battery system 10 if the battery pack 100 experiences thermal runaway for some reason. A heat insulating layer 204 may cover the battery pack 100 and insulate the battery pack 100 from the outside of the battery pack 100. A radiant heat reflecting layer 205 may cover the heat insulating layer 204, and the radiant heat reflecting layer 205 may reflect radiant heat from the battery pack 100 toward the battery pack 100. The battery pack 100 may be fixed to the base plate 201, and the base plate 201 may be fixed to the aircraft 70.

[0049] 11 schematically illustrates an example of a HAPS 700 equipped with a battery system 10. The HAPS 700 is an air vehicle that provides wireless communication services to user terminals 30 within a communication area 704 formed by emitting a beam 702 toward the ground. The HAPS 700 may be an example of an air vehicle that includes the battery system 10 and a thrust generating device that generates thrust using electrical energy stored in the battery system 10.

[0050] HAPS 700 includes a body 710, a center section 720, a propeller 730, a pod 740, and solar panels 750. The body 710 includes a wing section 712. The wing section 712 includes a left wing section 714 and a right wing section 716.

[0051] For example, a battery system 10 is disposed inside the wing section 712. The electrical energy stored in the battery system 10 is utilized by each component of the HAPS 700. For example, the electrical energy stored in the battery system 10 is utilized by the motor of the propeller 730 that generates propulsion force. As a specific example, a plurality of battery systems 10 connected in parallel are disposed inside the wing section 712. Of the plurality of battery systems 10, the left plurality of battery systems 10 may be disposed in the left wing section 714, and the right plurality of battery systems 10 may be disposed in the right wing section 716. The power discharged by the plurality of battery systems 10 is utilized by each component of the HAPS 700. For example, the power discharged by the plurality of battery systems 10 is utilized by the motor of the propeller 730.

[0052] A flight control unit 722 and a communication control unit 724 are disposed within the central unit 720. The flight control unit 722 controls the flight of the HAPS 700 using power discharged by the multiple battery systems 10. The communication control unit 724 controls the communication of the HAPS 700 using power discharged by the multiple battery systems 10.

[0053] The flight control unit 722 controls the flight of the HAPS 700, for example, by controlling the rotation of the propeller 730. The flight control unit 722 may also control the flight of the HAPS 700 by changing the angles of flaps or elevators (not shown). The flight control unit 722 may include various sensors, such as a positioning sensor such as a GPS sensor, a gyro sensor, and an acceleration sensor, and may manage the position, movement direction, and movement speed of the HAPS 700.

[0054] The communication control unit 724 forms a communication area 704 on the ground using a service link (SL) antenna. The communication control unit 724 forms a service link with a terrestrial user terminal 30 using the SL antenna. The SL antenna may be a multi-beam antenna. The communication area 704 may be multi-cell.

[0055] The communication control unit 724 may use a Feeder Link (FL) antenna to form a feeder link with the terrestrial gateway 40. The communication control unit 724 may access the network 20 via the gateway 40.

[0056] The communication control unit 724 may use a satellite communication antenna to communicate with the communication satellite 50. The communication control unit 724 may access the network 20 via the communication satellite 50 and the satellite communication station 60.

[0057] The user terminal 30 may be any communication terminal capable of communicating with the HAPS 700. For example, the user terminal 30 may be a mobile phone such as a smartphone. The user terminal 30 may also be a tablet terminal or a PC (Personal Computer). The user terminal 30 may also be a so-called IoT (Internet of Things) device. The user terminal 30 may include anything that falls under the so-called IoE (Internet of Everything).

[0058] The HAPS 700 relays communications between the network 20 and the user terminal 30, for example, via a feeder link or a communications satellite 50 and a service link. The HAPS 700 may provide wireless communication services to the user terminal 30 by relaying communications between the user terminal 30 and the network 20.

[0059] The network 20 includes a mobile communication network. The mobile communication network may conform to any of the following communication methods: LTE (Long Term Evolution), 5G (5th Generation), 3G (3rd Generation), and 6G (6th Generation) or later. The network 20 may include the Internet.

[0060] For example, the HAPS 700 transmits data received from a user terminal 30 within the communication area 704 to the network 20. Furthermore, for example, when the HAPS 700 receives data addressed to a user terminal 30 within the communication area 704 via the network 20, the HAPS 700 transmits the data to the user terminal 30.

[0061] The HAPS 700 maintains a communication area 704 in a specific area on the ground while circling a predetermined flight path in the stratosphere, for example. The HAPS 700 stores power generated by solar panels 750 in multiple battery systems 10 during the day and uses the power of the multiple battery systems 10 at night to maintain flight in the stratosphere. For example, the HAPS 700 ascends and stores potential energy while charging the multiple battery systems 10 during the day, and at night, it maintains flight in the stratosphere by gently descending and appropriately operating the propellers 730 and the like using the power of the battery systems 10.

[0062] The management device 800 manages multiple HAPS 700. The management device 800 may communicate with the HAPS 700 via the network 20 and the gateway 40. The management device 800 may communicate with the HAPS 700 via the network 20, the satellite communication station 60, and the communication satellite 50.

[0063] The management device 800 controls the HAPS 700 by sending instructions. The management device 800 may cause the HAPS 700 to circle above a target area on the ground so that the target area is covered by the communication area 704. For example, while flying in a circular orbit above the target area, the HAPS 700 adjusts the direction of orientation of the FL antenna to maintain a feeder link with the gateway 40, and adjusts the direction of orientation of the SL antenna to maintain coverage of the target area by the communication area 704.

[0064] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0065] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0066] 10 battery system, 20 network, 30 user terminal, 40 gateway, 50 communications satellite, 60 satellite communications station, 70 flying vehicle, 100 battery pack, 200 battery case, 201 base plate, 202 sealing layer, 203 vent valve, 204 thermal insulation layer, 205 radiant heat reflection layer, 210 pressure regulating valve, 212 housing portion, 214 valve body portion, 216 elastic portion, 220 pressure regulating valve, 222 housing portion, 224 valve body portion, 226 elastic portion, 700 HAPS, 702 beam, 704 communication area, 710 fuselage, 712 wing portion, 714 left wing portion, 716 right wing portion, 720 center portion, 722 flight control unit, 724 communication control unit, 730 propeller, 740 pod, 750 Solar panel, 800 management device

Claims

1. A battery system for an aircraft, comprising: a battery pack; and an airtight battery case for accommodating the battery pack, the compressive fracture strength of the battery case is equal to or less than a pressure corresponding to a pressure difference between an air pressure at a maximum flight altitude of the aircraft and an air pressure at a minimum flight altitude of the aircraft; the battery case has a first pressure regulating valve that adjusts the case pressure difference, which is the pressure difference between the atmospheric pressure outside the battery case and the atmospheric pressure inside the battery case, by introducing gas outside the battery case into the battery case so that the case pressure difference is smaller than the compressive fracture strength, the first pressure regulating valve being configured not to open from the time the aircraft takes off until it reaches the maximum flight altitude and descends from the maximum flight altitude to a predetermined first altitude, and to open at an altitude lower than the first altitude; Battery system.

2. the expansion and fracture strength of the battery case is greater than a pressure corresponding to a pressure difference between the atmospheric pressure at the highest flight altitude and the atmospheric pressure at the lowest flight altitude; The battery system according to claim 1 .

3. 2. The battery system according to claim 1, wherein the battery case further comprises a second pressure regulating valve that releases gas from the battery case to the outside of the battery case to adjust the case pressure difference so that expansion and deformation of the battery case due to the case pressure difference does not exceed a predetermined deformation range.

4. the expansion and fracture strength of the battery case is equal to or less than a pressure corresponding to a pressure difference between the atmospheric pressure at the highest flight altitude and the atmospheric pressure at the lowest flight altitude; the battery case further includes a second pressure regulating valve that adjusts the case pressure difference by releasing gas inside the battery case to the outside of the battery case so that the case pressure difference becomes smaller than the expansion and fracture strength, the second pressure regulating valve being configured not to open while the flight altitude of the aircraft is equal to or higher than the first altitude and to open at an altitude lower than the first altitude; The battery system according to claim 1 .

5. The battery system according to claim 1 , wherein the first altitude is determined by an ozone concentration at each altitude.

6. The battery system according to claim 1 , wherein the first altitude is a minimum flight altitude during a period in which the flying object continues to fly in the air.

7. the first pressure regulating valve is configured to open in response to the case pressure differential exceeding a first pressure threshold within a predetermined first pressure threshold range; The battery system according to claim 1 , wherein the first pressure threshold range includes 20 kPa.

8. The battery system of claim 7 , wherein the first pressure threshold is 20 kPa.

9. The battery system of claim 7 , wherein the first pressure threshold is 15 kPa.

10. The battery system according to claim 1 , wherein the maximum flight altitude is a stratospheric altitude.

11. 5. The battery system according to claim 1, wherein the first pressure regulating valve includes a valve body portion and an elastic body portion, the elastic body portion is configured to close the valve body portion by pressing the valve body portion, and the first pressure regulating valve is made of plastic, or a portion of the first pressure regulating valve excluding the elastic body portion is made of plastic.

12. The aircraft flies in the stratosphere, 12. The battery system of claim 11, wherein the pressing force applied by the elastic body portion of the first pressure regulating valve to the valve body portion is configured to prevent the valve from opening while the aircraft is flying in the stratosphere.

Images