Battery module and battery cooling system

Abstract

This battery module comprises: a plurality of battery cells (220); a housing part (210); a heat storage part (230); valve joints (240, 250); and a cooling fluid passage (270). The housing part houses the plurality of battery cells. The heat storage part is disposed between adjacent battery cells, exchanges heat with the battery cells, and stores heat of the battery cells. The valve joints are provided in the housing part for the detachment and attachment of a cooling device (400) for supplying cooling fluid (600) into the housing part. The cooling fluid passage is provided between the adjacent battery cells and the heat storage part, and is configured to allow circulation of the cooling fluid supplied into the storage part. The battery cells and the heat storage part are connected by at least two connection parts (233, 281, 282). Gaps (235, 284) are formed between the battery cells and the heat storage part where the battery cells and the heat storage part are not connected by the connection parts. The cooling fluid passage is composed of the gaps formed between adjacent connection parts.

Description

Battery module and battery cooling system CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2023-205557, filed on December 5, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a battery module and a battery cooling system.

[0003] Patent Document 1 describes a battery module having a heat receiving portion sandwiched between battery cells to receive heat from the battery cells, and a cooling portion formed integrally with the heat receiving portion and projecting from the battery cells. In this prior art, a cooling fluid is supplied to the cooling portion to efficiently dissipate heat from the battery cells.

[0004] JP 2011-243358 A

[0005] When a battery module is installed in an electric aircraft, the cooling performance required differs between when the aircraft is in flight and when it is on the ground after landing. To be more specific, a lightweight design is required when the aircraft is in flight, so a minimum level of cooling performance must be ensured while simplifying the configuration required for cooling the battery pack. Meanwhile, when the aircraft is on the ground, high-performance cooling is required to deal with heat generated by rapid charging of the battery pack.

[0006] In view of the above, an object of the present disclosure is to provide a battery module and a battery cooling system that can easily adjust the cooling performance for battery cells.

[0007] In order to achieve the above object, a battery module according to one embodiment of the present disclosure comprises: a plurality of battery cells; a storage section for storing the plurality of battery cells; a heat storage section arranged between adjacent battery cells, exchanging heat with the battery cells and storing heat from the battery cells; a valve fitting provided in the storage section to which a cooling device that supplies cooling fluid into the storage section is detachably attached; and a cooling fluid passage provided between adjacent battery cells and the heat storage section, through which the cooling fluid supplied into the storage section can flow, wherein the battery cells and the heat storage section are connected by at least two connection sections; and a gap is formed between the battery cells and the heat storage section in the portions of the battery cells and the heat storage section that are not connected by the connection sections, and the cooling fluid passage is constituted by the gap formed between adjacent connection sections.

[0008] Furthermore, a battery cooling system according to one aspect of the present disclosure includes a battery module including: a plurality of battery cells; a storage section for storing the plurality of battery cells; a heat storage section disposed between adjacent battery cells, exchanging heat with the battery cells and storing heat from the battery cells; a valve fitting provided in the storage section to which a cooling device that supplies cooling fluid into the storage section is detachably attached; a cooling device that cools and stores the cooling fluid; and a control device that controls the cooling device, wherein the battery module and the cooling device are connected via the valve fitting to form a cooling circulation circuit that allows the cooling fluid to circulate between the battery module and the cooling device, and the control device circulates the cooling fluid that has been previously cooled by the cooling device through the cooling circulation circuit, and after circulating the cooling fluid, discharges at least a portion of the cooling fluid in the storage section via the cooling circulation circuit.

[0009] Furthermore, a battery cooling system according to one aspect of the present disclosure includes a battery module including: a plurality of battery cells; a storage section for storing the plurality of battery cells; a heat storage section disposed between adjacent battery cells, exchanging heat with the battery cells and storing heat from the battery cells; a valve fitting provided in the storage section to which a cooling device that supplies cooling fluid into the storage section is detachably attached; a cooling device that cools and stores the cooling fluid; and a control device that controls the cooling device, wherein the battery module and the cooling device are connected via the valve fitting to form a cooling flow path through which the cooling fluid can flow between the battery module and the cooling device, and the control device fills the battery module with cooling fluid that has been cooled in advance by the cooling device from the cooling device through the cooling flow path, and after filling the battery module with the cooling fluid, discharges at least a portion of the cooling fluid in the storage section through the cooling flow path.

[0010] According to this, when the cooling device is not connected to the valve joint, heat storage cooling is performed, in which heat from each battery cell is absorbed by the heat storage section. On the other hand, when the cooling device is connected to the valve joint, immersion cooling is performed, in which the battery cells are immersed in a cooling fluid and cooled. Therefore, simply by attaching or detaching the cooling device to or from the valve joint, the cooling method for the battery cells can be switched and the cooling performance for the battery cells can be adjusted. This makes it possible to easily adjust the cooling performance for the battery cells.

[0011] 1 is a diagram showing a schematic configuration of an eVTOL in a first embodiment. FIG. 2 is an explanatory diagram showing a battery cooling system during flight in the first embodiment. FIG. 3 is a top view showing a battery module during flight in the first embodiment. FIG. 4 is an explanatory diagram showing a battery cooling system on the ground in the first embodiment. FIG. 5 is a top view showing a battery module on the ground in the first embodiment. FIG. 6 is a diagram showing changes in battery output and battery temperature from takeoff to landing of the eVTOL in the first embodiment. FIG. 7 is a top view showing a battery module during flight in a modified example. FIG. 8 is an explanatory diagram showing a battery cooling system on the ground in the second embodiment. FIG. 9 is an explanatory diagram showing a battery cooling system on the ground in the second embodiment. FIG. 10 is an explanatory diagram showing a battery cooling system on the ground in the third embodiment. FIG. 11 is an explanatory diagram showing a battery cooling system on the ground in the third embodiment. FIG. 12 is a top view showing a battery module during flight in the fourth embodiment. FIG. 13 is a top view showing a battery module during flight in the fifth embodiment. FIG. 14 is a top view showing a battery module during flight in the sixth embodiment. FIG. 15 is a top view showing a battery module during flight in a modified example.

[0012] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, the other previously described embodiments may be applied to the other parts of the configuration.

[0013] In each embodiment, it is possible to combine parts that are specifically expressly possible to combine with each other. Furthermore, even if it is not expressly expressly possible to combine, it is also possible to combine parts of embodiments with each other, as long as there is no particular problem with the combination.

[0014] First Embodiment A battery module according to this embodiment is mounted on an electric vehicle. The electric vehicle is an electric flying object, an electric vehicle, etc. The electric flying object is capable of flying by being driven by a rotating electric machine.

[0015] Examples of electric flying vehicles include electric vertical take-off and landing aircraft (eVTOL), electric short take-off and landing aircraft (eSTOL), drones, etc. eVTOL is an abbreviation for electronic vertical take-off and landing aircraft. eSTOL is an abbreviation for electronic short distance take-off and landing aircraft. In the following, an example in which a battery module is installed in an eVTOL will be described.

[0016] <eVTOL> As shown in FIG. 1 , an eVTOL 100 according to the present embodiment includes, as an example, an aircraft body 110 , fixed wings 120 , rotary wings 130 , a lift control mechanism 140 , a battery module 200 , an EPU 150 , a BMS 160 , and an ECU 170 .

[0017] The aircraft main body 110 is the fuselage of the aircraft. The aircraft main body 110 has a shape that extends in the front-to-rear direction. The aircraft main body 110 has a passenger compartment for passengers and / or a luggage compartment for carrying luggage.

[0018] The fixed wing 120 is a wing portion of the aircraft and is connected to the aircraft body 110. The fixed wing 120 provides gliding lift. The gliding lift is the lift generated by the fixed wing 120. As an example, the fixed wing 120 has a main wing 121 and a tail 122. The main wing 121 extends left and right from near the center of the aircraft body 110 in the fore-and-aft direction. The tail 122 extends left and right from the rear of the aircraft body 110. The shape of the fixed wing 120 is not particularly limited. For example, a swept wing, a delta wing, a straight wing, etc. can be used.

[0019] A plurality of rotors 130 are provided on the airframe. At least some of the plurality of rotors 130 may be provided on the fixed wing 120. At least some of the plurality of rotors 130 may be provided on the airframe main body 110. The number of rotors 130 provided on the eVTOL 100 is not particularly limited. As an example, a plurality of rotors 130 are provided on each of the airframe main body 110 and the main wing 121. The eVTOL 100 is provided with six rotors 130.

[0020] The rotor 130 may be referred to as a rotor, a propeller, a fan, etc. The rotor 130 has blades 131 and a shaft 132. The blades 131 are attached to the shaft 132. The blades 131 are vanes that rotate together with the shaft 132. A plurality of blades 131 extend radially around the axis of the shaft 132. The shaft 132 is the rotation axis of the rotor 130, and is driven to rotate by the motor of the EPU 150.

[0021] Rotor 130 generates thrust by rotation. The thrust acts on eVTOL 100 primarily as rotational lift during takeoff and landing. Rotor 130 primarily provides rotational lift during takeoff and landing. Rotational lift is lift generated by the rotation of rotor 130. During takeoff and landing, rotor 130 may provide only rotational lift, or may provide forward thrust in addition to rotational lift. Rotor 130 provides rotational lift during eVTOL 100 hovering.

[0022] The propulsive force acts primarily as thrust on eVTOL 100 during cruise of eVTOL 100. Rotor 130 primarily provides thrust during cruise. During cruise, rotor 130 may provide thrust alone or may provide lift in addition to thrust.

[0023] The lift adjustment mechanism 140 adjusts the gliding lift of the fixed wing 120. The lift adjustment mechanism 140 increases or decreases the gliding lift generated by the fixed wing 120. The lift adjustment mechanism 140 adjusts the gliding lift by adjusting at least one of the surface area, angle of attack (AOA), camber (wing curvature), stall AOA, and wing speed of the fixed wing 120, for example. AOA is an abbreviation for Angle Of Attack. As an example, the lift adjustment mechanism 140 has a tilt mechanism 141 and a flap 142.

[0024] The tilt mechanism 141 is driven to adjust the tilt angle of the rotor 130. The tilt mechanism 141, together with a motor, an inverter, and the like that drive the tilt mechanism 141, constitutes a tilt adjustment device. The tilt adjustment device including the tilt mechanism 141 is provided, for example, individually for each rotor 130. The tilt mechanism 141 adjusts the tilt angle of the rotor 130 by adjusting the relative inclination of the rotor 130 with respect to the airframe.

[0025] During takeoff and landing, tilt mechanism 141 controls the tilt angle so that the axis of each rotor 130 approaches a position parallel to the vertical direction. As a result, the thrust generated by the rotation of each rotor 130 acts on eVTOL 100 primarily as rotational lift. This allows eVTOL 100 to take off and land in a short distance or in a vertical direction. In FIG. 1 , the vertical direction is perpendicular to the plane of the page.

[0026] During cruising, tilt mechanism 141 controls the tilt angle so that the axis of each rotor 130 approaches a position parallel to the horizontal. As a result, the propulsive force generated by the rotation of each rotor 130 acts primarily as thrust on eVTOL 100. Therefore, eVTOL 100 can move forward using the forward thrust generated by the rotation of each rotor 130 while obtaining gliding lift from fixed wing 120. Furthermore, gliding lift can be adjusted by changing the wing speed using thrust.

[0027] Although the example in which the tilt mechanisms 141 are provided individually for the rotors 130 has been described, the present invention is not limited to this. For example, the tilt angles of multiple rotors 130 arranged side by side may be controlled by a common tilt mechanism. Alternatively, the rotors 130 may be integrated with a portion of the wing section, and the portion of the wing section and the rotors 130 may be displaced integrally by the tilt mechanism.

[0028] The flap 142 is a movable wing piece and is provided on the fixed wing 120. The flap 142, together with a motor, an inverter, and the like that drive the flap 142, constitutes a flap adjustment device. The flap 142 is sometimes referred to as a high-lift device. As an example, a plurality of flaps 142 are provided on the trailing edge of the main wing 121. Each of the plurality of flaps 142 is provided with a motor and an inverter. The flap 142 may be provided on the tail 122 in addition to the main wing 121. The flap 142 may also be provided on the leading edge of the fixed wing 120.

[0029] The flaps 142 adjust the surface area and camber of the fixed wing 120. For example, by controlling the flaps 142 provided on the main wing 121 to a lower position, the gliding lift acting on the main wing 121 increases. In addition, by moving the flaps 142 in a direction that protrudes from the main wing 121, it is possible to further increase the gliding lift.

[0030] The lift adjustment mechanism 140 is not limited to the tilt mechanism 141 and the flap 142 described above. A tilt mechanism that adjusts the relative inclination of the fixed wing 120 with respect to the aircraft body 110 may be employed as the lift adjustment mechanism 140. In this case, the angle of attack of the fixed wing 120 can be adjusted. A thrust rotor provided separately from the rotor 130 may be employed as the lift adjustment mechanism 140. In this case, the wing speed can be adjusted. Furthermore, by providing a thrust rotor, the rotor 130 can be dedicated to lift (i.e., rotational lift).

[0031] A variable wing may be used as the lift adjustment mechanism 140. Lift can be adjusted by changing the surface area, camber, angle of attachment, etc. of the fixed wing 120. A high-lift device other than the flap 142, such as a slat, may be used as the lift adjustment mechanism 140. The slat is provided on the leading edge of the main wing 121. By moving the slat forward relative to the main wing 121, a gap is created between the slat and the main wing 121, delaying separation. This allows for increased lift without stalling up to a higher angle of attack. In other words, the stall AOA can be delayed.

[0032] The battery module 200 has a plurality of battery cells (described later) and is a device capable of cooling each battery cell. Each battery cell is a rechargeable secondary battery capable of storing DC power. Each battery cell supplies power to the EPU 150, the ECU 170, the tilt adjustment device, and the flap adjustment device. Each battery cell also supplies power to auxiliary equipment (not shown), such as an air conditioner.

[0033] As an example, the eVTOL 100 of this embodiment includes a plurality of battery modules 200. The plurality of battery modules 200 may be connected to each other in series and / or parallel, or may be arranged independently without being connected to each other. The battery modules 200 may be provided individually for the EPU 150, or may be provided redundantly for the EPU 150.

[0034] Here, the battery modules 200 are heavy because they include, for example, tens or hundreds of battery cells. Therefore, by arranging each battery module 200 at two locations on each side of the main wing 121, the balance of the airframe main body 110 can be maintained. Of course, the battery modules 200 may also be arranged in the airframe main body 110.

[0035] The EPU 150 has a motor and an inverter, and rotates the rotors 130 that provide propulsive force to the eVTOL 100. EPU is an abbreviation for Electric Propulsion Unit. As an example, the number of EPUs 150 provided is the same as the number of rotors 130. In other words, the eVTOL 100 includes six EPUs 150. The EPUs 150 and the rotors 130 are connected one-to-one. Alternatively, two or more rotors 130 may be connected to one EPU 150 via a gearbox.

[0036] The BMS 160 monitors the state of each battery pack 260 (see FIG. 2 described below) of the battery module 200. BMS is an abbreviation for Battery Management System. For example, one BMS 160 is provided for each battery module 200. By monitoring the state of each battery pack 260 of each of the multiple battery modules 200, the BMS 160 may, for example, predict or detect an abnormality in each battery module 200.

[0037] ECU 170 controls the flight of eVTOL 100. ECU is an abbreviation for Electronic Control Unit. ECU 170 controls the flight of eVTOL 100 in a flight state according to operation by a pilot as an operator, remote operation by an operator, or control by a control system. ECU 170 executes flight control based on detection results from BMS 160 and various sensors. ECU 170 controls the drive of, for example, the motor of EPU 150, the motor of the tilt adjustment device, and the motor of the flap adjustment device. ECU 170 may also execute control of auxiliary equipment.

[0038] <Battery Cooling System> As shown in Figure 2, the battery cooling system 300 of this embodiment includes a battery module 200, a cooling device 400, and a control device 500. The up-and-down direction when the eVTOL 100 is stationary on the ground is referred to as the vertical direction. In the vertical direction, the upper side refers to the sky and the lower side refers to the ground. The vertical direction corresponds to the direction of gravity.

[0039] As shown in FIGS. 2 and 3 , the battery module 200 of this embodiment includes a cooling tank 210 , a plurality of battery cells 220 , a heat storage tube 230 , and valve joints 240 and 250 .

[0040] The cooling tank 210 is a housing that houses the battery cells 220 and the heat storage tubes 230. The cooling tank 210 constitutes the housing of the battery module 200. The cooling tank 210 has an outer wall surface 211 and an inner wall surface 212, and also has a space 213 inside. The cooling tank 210 is formed using, for example, an aluminum-based metal material or a resin material. As an example, the cooling tank 210 in this embodiment is formed using an aluminum-based material.

[0041] The cooling tank 210 may have, for example, a lid 214 configured as an upper portion in the vertical direction. The lid 214 is attachable to and detachable from the other portions. This allows multiple battery cells 220 and heat storage tubes 230 to be inserted into and removed from the space 213 of the cooling tank 210. The interior of the cooling tank 210 may be sealed, or it may not be completely sealed.

[0042] The battery cell 220 is a secondary battery that generates an electromotive force through a chemical reaction. The battery cell 220 is, for example, a lithium-ion secondary battery, a nickel-metal hydride secondary battery, an organic radical battery, etc. The battery cell 220 may be a secondary battery with a liquid electrolyte, or a so-called all-solid-state battery with a solid electrolyte.

[0043] A plurality of battery cells 220 are housed in the space 213 of the cooling tank 210. The plurality of battery cells 220 have a common structure. There are no particular limitations on the number or arrangement of the plurality of battery cells 220. The plurality of battery cells 220 may be connected in series, or may be connected in parallel and in series. As an example, the battery cells 220 in this embodiment are connected in series. An electrically connected structure of the plurality of battery cells 220 is sometimes called a battery pack.

[0044] The battery cell 220 has a power generating element and a battery case that houses the power generating element. The battery case provides the outer shell of the battery cell 220. The battery case is formed using, for example, a metal material. The shape of the battery cell 220, i.e., the battery case, is not particularly limited. For example, a cylindrical shape, a rectangular shape, or the like can be adopted. As an example, the battery cell 220 of this embodiment has a rectangular shape, specifically a thin, flat shape.

[0045] The battery cell 220 is, for example, a laminated battery. The battery cell 220 has a top surface, a bottom surface, and four side surfaces. The top surface is the surface facing upward in the vertical direction. The bottom surface is the surface opposite the top surface in the vertical direction and faces the ground. The side surface is a surface connecting the top surface and the bottom surface and is a surface along the vertical direction. As an example, the multiple battery cells 220 in this embodiment are arranged side by side in a direction perpendicular to the vertical direction.

[0046] Each battery cell 220 has two electrode terminals. One electrode terminal is electrically connected to the positive electrode of the battery cell 220. This electrode terminal may be referred to as a positive electrode terminal, a P terminal, or the like. The other electrode terminal is electrically connected to the negative electrode of the battery cell 220. The other electrode terminal may be referred to as a negative electrode terminal, an N terminal, or the like. The electrode terminals may be referred to as current collecting tabs.

[0047] A heat storage tube 230 is disposed between adjacent battery cells 220. The heat storage tube 230 is a heat transfer member that transfers heat between the battery cells 220. The heat storage tube 230 is also a heat storage section that incorporates a heat storage material 231. In other words, the inside of the heat storage tube 230 is filled with the heat storage material 231.

[0048] The heat storage material 231 is a member that has a heat storage effect. The heat storage material 231 cools the battery cells 220 by absorbing heat generated in the battery cells 220. The heat storage material 231 is, for example, a latent heat storage material. Instead of a latent heat storage material, water or cooling water to which LLC has been added may be used as the heat storage material 231. LLC is an abbreviation for Long Life Coolant. The heat storage material is sometimes called a cold storage material.

[0049] As an example, the heat storage material 231 in this embodiment is a latent heat storage material. A latent heat storage material is sometimes referred to as a PCM. PCM is an abbreviation for phase change material. A latent heat storage material changes phase between solid and liquid. A latent heat storage material utilizes the latent heat of a substance. The latent heat storage material maintains the temperature of the battery cell 220 at a predetermined temperature or within a predetermined temperature range. For example, a non-hydrate carbon compound, specifically a paraffin-based material, may be used as the latent heat storage material. Instead of a paraffin-based material, a hydrate-based material may be used as the latent heat storage material. Hydrate-based materials include, for example, hydrates of sodium acetate, sodium sulfate, sodium nitrate, etc.

[0050] As an example, the heat storage material 231 in this embodiment is a non-hydrate carbon compound, i.e., a paraffin-based heat storage material, and the phase transition temperature between the solid phase and the liquid phase of the heat storage material 231 is set within the range of 30°C to 60°C.

[0051] A plurality of heat storage tubes 230 are arranged in the space 213 of the housing portion 210. In this embodiment, as an example, one heat storage tube 230 is arranged between each of the adjacent battery cells 220.

[0052] The heat storage tube 230 is in thermal contact with the battery cell 220. Details of the heat storage tube 230 will be described later.

[0053] The battery pack 260 is made up of the plurality of battery cells 220 and heat storage tubes 230 stacked as described above. Hereinafter, the stacking direction of the battery cells 220 in the battery pack 260 will be referred to as the cell stacking direction.

[0054] The battery cells 220 and the heat storage tubes 230 are arranged so that their upper surfaces are positioned at approximately the same height in the vertical direction. The battery cells 220 and the heat storage tubes 230 are fixed in their relative positions by a fixing member (not shown). The fixing member may be, for example, a case or a restraining member such as a belt-like band.

[0055] In the above-described arrangement, the electrode terminals of adjacent battery cells 220 are electrically connected to each other by a bus bar (not shown) which is a wiring member. In other words, the plurality of battery cells 220 are connected in series by the bus bar.

[0056] Two bus bars, one for the positive electrode and one for the negative electrode, protrude from a space 213 of the cooling tank 210 to the outside of the cooling tank 210. When the cooling tank 210 is made of a metal material, an insulating part (not shown) such as an insulating seal material is disposed in the portion of the cooling tank 210 through which the bus bars pass, thereby achieving electrical insulation and sealing between the cooling tank 210 and the bus bars.

[0057] 4, the valve joints 240 and 250 are detachable parts to which the cooling device 400 is attached and detached. That is, the cooling tank 210 is attached and detached to and from the cooling device 400 via the valve joints 240 and 250. The valve joints 240 and 250 allow the passage of the cooling fluid 600 when connected to the cooling device 400, but block the passage of the cooling fluid 600 when not connected to the cooling device 400. The cooling fluid 600 will be described in detail later.

[0058] For example, the valve joints 240, 250 may be manually switched to the open state after the cooling device 400 is connected. Alternatively, the valve joints 240, 250 may be manually switched to the closed state before the cooling device 400 is disconnected. Alternatively, the valve joints 240, 250 may be mechanically switched to the open state when the cooling device 400 is connected to the valve joints 240, 250. Alternatively, the valve joints 240, 250 may be mechanically switched to the closed state when the cooling device 400 is disconnected from the valve joints 240, 250.

[0059] Here, the central position of the cooling tank 210 in the vertical direction is defined as the reference position. In this embodiment, one valve joint 240 is provided above the reference position in the cooling tank 210. The other valve joint 250 is provided below the reference position in the cooling tank 210.

[0060] Hereinafter, the valve joint 240 provided above the reference position in the cooling tank 210 will also be referred to as the first valve joint 240. The valve joint 250 provided below the reference position in the cooling tank 210 will also be referred to as the second valve joint 250.

[0061] As a result, for example, when the cooling fluid 600 inside the cooling tank 210 is discharged to the outside via the second valve joint 250, the cooling fluid 600 can be discharged to the outside from the cooling tank 210 by gravity. In this case, the cooling fluid 600 located above the second valve joint 250 in the vertical direction can be discharged to the outside.

[0062] Both the first valve joint 240 and the second valve joint 250 may be provided in the vertical direction below a reference position in the cooling tank 210. Alternatively, both the first valve joint 240 and the second valve joint 250 may be provided in the vertical direction above a reference position in the cooling tank 210. In other words, it is sufficient that the first valve joint 240 and the second valve joint 250 are each provided at a position in the cooling tank 210 where the cooling fluid 600 is present.

[0063] By displacing the valve joints 240 and 250 vertically or horizontally, it is possible to discharge a large amount of the cooling fluid 600 from the cooling tank 210 and circulate the cooling fluid with less stagnation (i.e., non-flowing portions). Furthermore, each of the valve joints 240 and 250 may be connected to the cooling tank 210 via a pipe.

[0064] The cooling device 400 is a device that cools and stores the cooling fluid 600. The cooling device 400 is also a device that is connected to the valve joints 240 and 250 of the cooling tank 210, thereby allowing the cooling fluid 600 inside the cooling tank 210 to flow in and out.

[0065] The cooling fluid 600 is a heat medium that is supplied to the space 213 of the cooling tank 210 when the cooling device 400 is connected to the valve joints 240, 250 of the cooling tank 210. The cooling fluid 600 is a cooling fluid that immerses each battery cell 220 and absorbs heat from each battery cell 220 to cool each battery cell 220 when the cooling device 400 is connected to the valve joints 240, 250 of the cooling tank 210.

[0066] When the cooling device 400 is connected to the valve joints 240, 250, each battery cell 220 may be entirely immersed in the cooling fluid 600, or only a portion of each battery cell 220 may be immersed in the cooling fluid 600. In this embodiment, as an example, each battery cell 220 is entirely immersed in the cooling fluid 600.

[0067] In this embodiment, an insulating liquid having insulating properties is used as the cooling fluid 600. For example, a non-flammable fluorine-based liquid can be used as the insulating liquid. Non-flammable means that the substance or object does not burn and is not likely to spread due to sparks or heat, and also means that it is non-flammable. A non-flammable fluorine-based insulating liquid can suppress thermal chain reactions when the battery cell 220 experiences thermal runaway, or can even prevent thermal chain reactions altogether. In other words, a fluorine-based insulating liquid has the advantage of being highly safe.

[0068] Examples of non-flammable fluorine-based insulating liquids that can be used include Galden (registered trademark) manufactured by Solvay, Asahiklin (registered trademark) manufactured by AGC, and Opteon (registered trademark) manufactured by Chemours.

[0069] Another example of the insulating liquid is oil. Oil has low volatility, which reduces leakage from the cooling tank 210 to the outside. Oil is also less expensive than the fluorine-based insulating liquid described above.

[0070] As the oil, for example, SPECTRASYN (registered trademark) from ExxonMobil Corporation, SYNFLUID (registered trademark) from Chevron Phillips Chemical Company, and MIVOLT (registered trademark) from M&I Materials, Inc. Also, as other oil, for example, AmpCool from Engineered Fluids, Inc. and silicone oil from Shin-Etsu Chemical Co., Ltd. can be used.

[0071] The cooling device 400 of this embodiment includes a tank 410, pipes 420 and 430, and a pump 440. The tank 410 stores the cooling fluid 600. The pipes 420 and 430 are connected to the tank 410. The pump 440 pumps the cooling fluid 600 in the tank 410 to the pipe 430. Although not shown, the cooling device 400 also includes a cooling facility that cools and keeps the cooling fluid 600 in the tank 410 warm.

[0072] The pipes 420, 430 are, for example, hoses. One pipe 420 is connected to the first valve joint 240. The other pipe 430 is connected to the second valve joint 250. In this way, by connecting the battery module 200 and the cooling device 400 via the valve joints 240, 250 and the pipes 420, 430, a cooling circulation circuit 460 is formed in which the cooling fluid 600 can circulate between the battery module 200 and the cooling device 400.

[0073] The other pipe 430 may be provided with a discharge valve for discharging the high-temperature cooling fluid 600 in the cooling tank 210. This allows the high-temperature cooling fluid 600 inside the cooling tank 210 to be quickly discharged. Of course, the other pipe 430 does not have to be provided with a discharge valve.

[0074] A cooling device 400 is provided for each battery module 200, for example. Alternatively, a single cooling device 400 may be provided with a plurality of sets of pipes 420, 430 arranged in parallel. In this case, each of the pipes 420, 430 is connected to each of the battery modules 200.

[0075] Cooling device 400 is connected to cooling tank 210 after eVTOL 100 lands (i.e., when on the ground). As shown in Figure 2, when eVTOL 100 takes off, cruises, or lands (i.e., when in flight), battery module 200 is detached from cooling device 400 and is located inside eVTOL 100. Cooling device 400 is located outside eVTOL 100.

[0076] Cooling device 400 may be connected to cooling tank 210 simultaneously with landing of eVTOL 100. Cooling device 400 may also be detached from cooling tank 210 simultaneously with takeoff of eVTOL 100.

[0077] The control device 500 is a device that controls the cooling device 400. The control device 500 controls, for example, the rotation speed (i.e., pumping capacity) of the pump 440 and the cooling temperature of the cooling equipment. The control device 500 is composed of a well-known microcomputer including a processor, ROM, RAM, etc., and its peripheral circuits. The control device 500 performs various calculations and processes based on a control program stored in the ROM.

[0078] When a plurality of cooling devices 400 are provided, a control device 500 may be provided for each battery module 200, or one control device 500 may control a plurality of battery modules 200.

[0079] 3 and 5 , a cooling fluid passage 270 is provided between adjacent battery cells 220 and heat storage tubes 230. The cooling fluid passage 270 is a passage through which the cooling fluid 600 can flow when the eVTOL 100 is on the ground, i.e., when the cooling device 400 is connected to the valve joints 240, 250.

[0080] As an example, the heat storage tube 230 of this embodiment has a base portion 232 and a plurality of protrusions 233. The base portion 232 is not in contact with the battery cells 220. The base portion 232 extends in a direction perpendicular to the cell stacking direction. As an example, in this embodiment, the base portion 232 extends in the top-to-bottom direction (the direction perpendicular to the paper surface of FIGS. 3 and 5 ).

[0081] The base portion 232 faces the battery cell 220 and has a non-contact surface 234 that does not come into contact with the battery cell 220. In other words, the surface of the base portion 232 that faces the battery cell 220 has the non-contact surface 234 that does not come into contact with the battery cell 220.

[0082] The multiple protrusions 233 are each formed to protrude from the non-contact surface 234 of the base portion 232 toward the adjacent battery cell 220. The protrusions 233 are in contact with the surfaces of the battery cells 220. In other words, the surfaces of the adjacent battery cells 220 and the surfaces of the heat storage tubes 230 are connected via at least two protrusions 233. Therefore, the protrusions 233 in this embodiment correspond to an example of a connection portion.

[0083] A gap 235 is formed between the battery cell 220 and the heat storage tube 230 at a portion of the battery cell 220 and the heat storage tube 230 that is not connected by the protrusion 233. The gap 235 formed between adjacent protrusions 233 forms a cooling fluid passage 270. More specifically, the cooling fluid passage 270 is formed by the gap 235 surrounded by two adjacent protrusions 233, a non-contact surface 234 located between the two protrusions 233, and the surface of the battery cell 220 that faces the non-contact surface 234.

[0084] As an example, in this embodiment, the base portion 232 and the plurality of protrusions 233 are integrally formed. The space in the base portion 232 that accommodates the heat storage material 231 is connected to the space in each of the protrusions 233 that accommodates the heat storage material 231. This allows the heat storage tube 230 to be filled with the heat storage material 231 and sealed by simply providing a single filling port (not shown) for filling the heat storage tube 230 with the heat storage material 231. In other words, there is no need to provide multiple filling ports. This simplifies the configuration of the heat storage tube 230.

[0085] 4, the cooling fluid passage 270 has an inlet portion 271 through which the cooling fluid 600 flows into the cooling fluid passage 270, and an outlet portion 272 through which the cooling fluid 600 flows out of the cooling fluid passage 270. The inlet portion 271 and the outlet portion 272 are provided at different locations. That is, the cooling fluid passage 270 penetrates in one direction. The cooling fluid passage 270 extends linearly.

[0086] In this embodiment, as an example, the cooling fluid passage 270 extends in the vertical direction. That is, the inlet portion 271 and the outlet portion 272 are arranged on the same straight line parallel to the vertical direction. For example, the inlet portion 271 is provided at the lower end of the cooling fluid passage 270, and the outlet portion 272 is provided at the upper end of the cooling fluid passage 270. Alternatively, the inlet portion 271 may be provided at the upper end of the cooling fluid passage 270, and the outlet portion 272 may be provided at the lower end of the cooling fluid passage 270.

[0087] 3 and 5, the heat storage tube 230 of this embodiment has, as an example, a plurality of first convex portions 2331 and a plurality of second convex portions 2332 as the convex portions 233. The first convex portions 2331 protrude from the base portion 232 toward one side in the cell stacking direction. The second convex portions 2332 protrude from the base portion 232 toward the other side in the cell stacking direction.

[0088] <Cooling Method> Next, a method for cooling each battery cell 220 in this embodiment will be described. When the eVTOL 100 is flying, that is, during takeoff, cruising, and landing, each battery module 200 mounted on the eVTOL 100 is not connected to the cooling device 400 as shown in FIG. 2 . Therefore, heat from each battery cell 220 is stored in the heat storage material 231 inside the heat storage tube 230. This suppresses a rise in temperature of each battery cell 220.

[0089] On the other hand, after eVTOL 100 lands, each battery module 200 mounted on eVTOL 100 is connected to cooling device 400 as shown in Figure 4. This forms a cooling circulation circuit 460 between battery module 200 and cooling device 400.

[0090] The control device 500 causes the pump 440 to circulate the cooling fluid 600, which has been pre-cooled in the cooling device 400, through the cooling circulation circuit 460. For example, the low-temperature cooling fluid 600 is caused to flow into the cooling tank 210 via the second valve joint 250, and the high-temperature cooling fluid 600 is returned to the tank 410 of the cooling device 400 via the first valve joint 240. In this case, the pump 440 is controlled to pump the low-temperature cooling fluid 600 through the piping 430. By circulating the cooling fluid 600 through the cooling circulation circuit 460 in this way, each battery cell 220 inside the cooling tank 210 is rapidly cooled.

[0091] Alternatively, the low-temperature cooling fluid 600 may be caused to flow into the cooling tank 210 via the first valve joint 240, and the high-temperature cooling fluid 600 may be returned to the tank 410 of the cooling device 400 via the second valve joint 250 of the cooling tank 210. This allows the low-temperature cooling fluid 600 to flow along the surfaces of each battery cell 220 and each heat storage tube 230, thereby enabling uniform and high-performance cooling of multiple battery cells 220. In this case, the pump 440 is controlled to pressure-feed the low-temperature cooling fluid 600 into the piping 420.

[0092] Thereafter, before takeoff of the eVTOL 100, the control device 500 causes the pump 440 to discharge at least a portion of the cooling fluid 600 in the cooling tank 210 through the cooling circulation circuit 460. For example, the cooling fluid 600 in the cooling tank 210 is returned to the tank 410 of the cooling device 400 through the first valve joint 240. In this case, the pump 440 is controlled to suck the cooling fluid 600 in the piping 420.

[0093] Before takeoff of the eVTOL 100, the control device 500 may drain all of the cooling fluid 600 from the cooling tank 210, or may drain a portion of the cooling fluid 600 from the cooling tank 210. As an example, in this embodiment, the control device 500 drains all of the cooling fluid 600 from the cooling tank 210.

[0094] <Flight Pattern> Figure 6 shows an example of the simplest flight pattern from takeoff to landing for the eVTOL 100. Note that the flight patterns of electric flying vehicles other than the eVTOL 100 are similar to those of the eVTOL 100.

[0095] The period from time T10 to time T11 is referred to as the takeoff period, takeoff time, departure period, departure time, etc. Hereinafter, the period from time T10 to time T11 is referred to as takeoff time. Takeoff time refers to the ascent of eVTOL 100 from a landed state to a cruising altitude. The period from time T11 to time T12 is referred to as the cruising period, cruising time, etc. The period from time T12 to time T13 is referred to as the landing period, landing time, arrival period, arrival time, etc. Hereinafter, the period from time T12 to time T13 is referred to as landing time. Landing time refers to the descent of eVTOL 100 from a cruising altitude at the destination to landing on the ground. For convenience, the required power, i.e., output, is assumed to be constant for each period in FIG. 6.

[0096] The eVTOL 100 ascends from the takeoff point to the altitude of the cruise start point during the period from time T10 to time T11. The eVTOL 100 cruises at a predetermined altitude during the period from time T11 to time T12. The eVTOL 100 descends from the altitude of the end point of time T12 to the landing point during the period from time T12 to time T13.

[0097] The movement of eVTOL 100 includes a primarily horizontal component during cruising, and a primarily vertical component during takeoff and landing. During takeoff and landing, when movement occurs in the vertical direction, a higher output is required for driving rotor 130 of eVTOL 100 than during cruising, for a predetermined continuous period of time.

[0098] This high output places a heavy load on the battery cells 220 and EPU 150, which are drive devices for driving the rotors 130. For example, the amount of heat generated by each battery cell 220 increases compared to cruising, causing the temperature to rise. This is because the heat generated by each battery cell 220 is proportional to the output.

[0099] After the eVTOL 100 lands, each battery cell 220 is charged on the ground. When charging of each battery cell 220 is complete, the eVTOL 100 takes off again and begins cruising.

[0100] The battery temperature of each battery cell 220 changes as follows when the eVTOL 100 is in flight (discharging) and on the ground (charging). First, at takeoff, the battery temperature of each battery cell 220 rises rapidly. During cruising, the battery output required is not as high as during takeoff, so the battery temperature of each battery cell 220 rises gradually. During landing, the battery output required is similar to that required during takeoff, so the battery temperature of each battery cell 220 rises rapidly.

[0101] During the flight (discharging) period from time T10 to time T13, from when eVTOL 100 takes off until it lands, heat storage material 231 in heat storage tube 230 stores and cools the heat of battery cell 220.

[0102] This makes it possible to suppress an increase in the battery temperature of the battery cells 220. Therefore, at time T13 when the landing of the eVTOL 100 is completed, the battery temperature of each battery cell 220 can be prevented from exceeding the battery allowable temperature.

[0103] The period from time T13 to time T16 is a ground (i.e., charging) period during which each battery cell 220 is charged on the ground and high-performance cooling is performed on each battery cell 220. First, at time T13, the cooling device 400 is attached to the cooling tank 210 of each battery module 200 of the eVTOL 100. As a result, as described above, the low-temperature cooling fluid 600 circulates through the cooling circulation circuit 460, causing the battery temperature to drop rapidly.

[0104] Furthermore, between time T13 and time T14, the bus bars of the battery module 200 are connected to the charging device. When the battery module 200 is connected to the cooling device 400, the bus bars of the battery module 200 may be connected to the charging device at the same time. The charging device may be included in the cooling device 400 or may be separate from the cooling device 400.

[0105] Charging of each battery cell 220 begins at time T14. As a result, each battery cell 220 generates heat, and the decrease in battery temperature becomes gradual. When charging of each battery cell 220 is completed at time T15, each battery cell 220 and bus bar no longer generates heat, and the battery temperature drops rapidly due to cooling by the low-temperature cooling fluid 600. Thus, high-performance cooling of each battery cell 220 is completed at time T16.

[0106] Then, after the high-performance cooling is completed at time T16, the cooling fluid 600 is discharged from the cooling tank 210 of each battery module 200 of the eVTOL 100. After time T16, the flight (i.e., discharging) and ground (i.e., charging) from time T10 to time T16 are repeated.

[0107] As described above, the battery module 200 of this embodiment includes a heat storage tube 230 provided between adjacent battery cells 220, and valve fittings 240, 250 to which the cooling device 400 that supplies cooling fluid 600 into the cooling tank 210 is detachably attached.

[0108] According to this, when the cooling device 400 is not connected to the valve joints 240, 250, heat storage cooling is performed in which heat from each battery cell 220 is absorbed by the heat storage tube 230. On the other hand, when the cooling device 400 is connected to the valve joints 240, 250, immersion cooling is performed in which the battery cells 220 are immersed in the cooling fluid 600 and cooled. Therefore, simply by attaching or detaching the cooling device 400 to or from the valve joints 240, 250, the cooling method for the battery cells 220 can be switched and the cooling performance for the battery cells 220 can be adjusted. As a result, the cooling performance for the battery cells 220 can be easily adjusted.

[0109] More specifically, for example, when eVTOL 100 is flying, cooling device 400 is removed from valve joints 240, 250. Meanwhile, heat generated by each battery cell 220 can be absorbed and cooled by heat storage material 231 of heat storage tube 230, which has been cooled to a low temperature in advance. Therefore, when eVTOL 100 is flying, cooling device 400 can be removed to reduce weight while suppressing temperature increases in battery cells 220.

[0110] On the other hand, for example, when the eVTOL 100 is on the ground, it is necessary to cool both the heat stored in the heat storage material 231 and each battery cell 220 during flight of the eVTOL 100 and the heat generated by rapid charging of each battery cell 220, so high-performance cooling is required.

[0111] In contrast, in the battery module 200 of this embodiment, when the eVTOL 100 is on the ground, the cooling device 400 is attached to the valve joints 240, 250. This allows the battery cells 220 to be cooled by being directly immersed in the cooling fluid 600, thereby enabling the heat storage material 231 and the battery cells 220 to be cooled with high efficiency.

[0112] Furthermore, in battery cooling system 300 of the present embodiment, before takeoff of eVTOL 100, control device 500 causes pump 440 to discharge cooling fluid 600 from cooling tank 210 via cooling circulation circuit 460. As a result, when eVTOL 100 is flying, cooling fluid 600 is not present in cooling tank 210, thereby enabling weight reduction.

[0113] Furthermore, in the battery module 200 of this embodiment, the heat storage tube 230 is provided with a plurality of protrusions 233 that protrude toward the adjacent battery cells 220, and the surface of the battery cells 220 and the surface of the heat storage tube 230 are connected via the plurality of protrusions 233. Gaps 235 formed between the adjacent protrusions 233 form cooling fluid passages 270.

[0114] This allows the cooling fluid passage 270 to be formed between adjacent battery cells 220 and heat storage tubes 230. Therefore, when the cooling device 400 is attached to the valve joints 240, 250, it is possible to improve the heat exchange efficiency between the battery cells 220 and the cooling fluid 600, and also improve the heat exchange efficiency between the heat storage tubes 230 and the cooling fluid 600. As a result, it is possible to cool the heat storage material 231 and the battery cells 220 with higher efficiency.

[0115] As a modified example, as shown in FIG. 7 , a thermally conductive material 237 may be interposed between the battery cell 220 and the heat storage tube 230 to improve adhesion between the battery cell 220 and the heat storage tube 230. The thermally conductive material 237 is generally called TIM, and is a thermally conductive grease, a thermally conductive gel, a thermally conductive sheet, a thermally conductive adhesive, or an adhesive sheet. TIM is an abbreviation for Thermal Interface Material. As an example, in this embodiment, a thermally conductive sheet is used as the thermally conductive material 237.

[0116] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to the drawings. The second embodiment differs from the first embodiment in the type of cooling fluid 600 and the configuration of the cooling device 400.

[0117] In the battery cooling system 300 of this embodiment, the boiling point of the cooling fluid 600 is lower than the heat resistance temperature (i.e., the upper limit operating temperature) of the battery cells 220. Therefore, the cooling fluid 600 can boil due to heat generated by the battery cells 220, and boiling cooling is performed in the cooling tank 210, where the cooling fluid boils and absorbs heat from the battery cells 220. As an example, in this embodiment, subcool boiling is performed, where the cooling fluid 600 in the cooling tank 210 boils in a state where it is a subcooled liquid whose temperature is lower than the boiling point.

[0118] In this embodiment, an insulating liquid (i.e., a boiling refrigerant) having a boiling point lower than the heat resistance temperature of the battery cell 220 is used as the cooling fluid 600. For example, an insulating liquid that boils at 10°C to 40°C can be used as the cooling fluid 600. Examples of insulating liquids that boil at 10°C to 40°C include Novec (registered trademark) manufactured by 3M, Fluorinert (registered trademark) manufactured by 3M, Galden (registered trademark) manufactured by Solvay, Asahiklin (registered trademark) manufactured by AGC, Opteon (registered trademark) manufactured by Chemours, and Solvre (registered trademark) manufactured by Solvex.

[0119] 8 , in the battery cooling system 300 of this embodiment, a condenser 470 that condenses the gaseous cooling fluid 600 is provided inside the tank 410 of the cooling device 400. The condenser 470 is a heat exchanger that exchanges heat between the cooling fluid 600 that has boiled due to heat generated by the battery cells 220 and a heat medium that is at a lower temperature than the cooling fluid 600, thereby cooling and condensing the cooling fluid 600.

[0120] Next, a description will be given of a method for cooling each battery cell 220 in this embodiment. The method for cooling each battery cell 220 while the eVTOL 100 is flying is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0121] After eVTOL 100 lands, each battery module 200 mounted on eVTOL 100 is connected to a cooling device 400 as shown in Fig. 8. This forms a cooling circulation circuit 460 between battery module 200 and cooling device 400.

[0122] The control device 500 causes the pump 440 to circulate the cooling fluid 600, which has previously been made into a subcooled liquid by the cooling device 400, through the cooling circulation circuit 460. For example, the control device 500 causes the cooling fluid 600, which has been made into a subcooled liquid, to flow into the cooling tank 210 via the second valve joint 250.

[0123] As a result, inside the cooling tank 210, the cooling fluid 600 boils due to the heat generated by the battery cells 220, generating gaseous cooling fluid 600. The gaseous cooling fluid 600 generated by boiling rises inside the cooling tank 210 and flows into the tank 410 of the cooling device 400 via the first valve joint 240.

[0124] In this case, the pump 440 is controlled to pump the cooling fluid 600, which has become a subcooled liquid, to the pipe 430. In this way, by circulating the cooling fluid 600 through the cooling circulation circuit 460, each battery cell 220 inside the cooling tank 210 is rapidly cooled.

[0125] Thereafter, before takeoff of the eVTOL 100, the control device 500 causes the pump 440 to discharge the cooling fluid 600 from the cooling tank 210 through the cooling circulation circuit 460, as shown in FIG. 9 . For example, the control device 500 returns the cooling fluid 600 in the cooling tank 210 to the tank 410 of the cooling device 400 through the first valve joint 240. In this case, the pump 440 is controlled to suck the cooling fluid 600 from the piping 420. Alternatively, the tank 410 may be positioned below the valve joint 240 provided at the top of the cooling tank 210, thereby allowing the cooling fluid 600 to be discharged from the cooling tank 210 to the tank 410 by gravity.

[0126] It is also possible to eliminate the pump 440 and allow the cooling fluid 600 to be filled from the tank 410 into the cooling tank 210 by gravity. This allows the configuration of the battery cooling system 300 to be simplified.

[0127] The cooling fluid 600 discharged from the cooling tank 210 flows into the tank 410. The gaseous cooling fluid is then condensed in the condenser 470 and stored in the tank 410.

[0128] As described above, the battery module 200 of this embodiment employs, as the cooling fluid 600, a boiling refrigerant having a boiling point lower than the heat resistance temperature of the battery cells 220. Therefore, when the cooling device 400 is attached to the valve joints 240, 250, the battery cells 220 are immersed and boil-cooled by the cooling fluid 600. This allows boil-cooling to be preferentially performed on parts of the multiple battery cells 220 that are hotter than other parts, thereby achieving a uniform temperature for the multiple battery cells 220.

[0129] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to the drawings. The third embodiment differs from the first embodiment in the configuration of the cooling device 400.

[0130] 10 and 11 , the battery cooling system 300 of this embodiment has a cooling fluid supply unit 710 and a cooling fluid recovery unit 720 as the cooling device 400. The cooling fluid supply unit 710 supplies the cooling fluid 600 to the cooling tank 210 of the battery module 200 when the eVTOL 100 is on the ground after landing. The cooling fluid recovery unit 720 recovers the cooling fluid 600 supplied into the cooling tank 210 by the cooling fluid supply unit 710.

[0131] In the battery module 200 of this embodiment, both the first valve joint 240 and the second valve joint 250 are provided below a reference position in the cooling tank 210. The relative positions of the first valve joint 240 and the second valve joint 250 are not particularly limited. As an example, in this embodiment, the first valve joint 240 and the second valve joint 250 are provided on opposite sides of the cooling tank 210 with the battery pack 260 in between.

[0132] The cooling fluid supply unit 710 has a supply tank 711, a supply pipe 712, and a supply pump 713. The operation of the supply pump 713 is controlled by a control signal output from the control device 500.

[0133] The supply tank 711 stores the cooling fluid 600. The supply pipe 712 is connected to the supply tank 711. The supply pump 713 pressure-feeds the cooling fluid 600 in the supply tank 711 to the supply pipe 712. Although not shown, the cooling fluid supply unit 710 also has cooling equipment that cools and keeps the cooling fluid 600 warm in the supply tank 711. The supply pipe 712 is, for example, a hose. The supply pipe 712 is connected to the second valve joint 250. In this way, the battery module 200 and the cooling fluid supply unit 710 are connected via the second valve joint 250 and the supply pipe 712, thereby forming a supply flow path 714, which is a cooling flow path through which the cooling fluid 600 can flow between the battery module 200 and the cooling fluid supply unit 710.

[0134] The cooling fluid recovery unit 720 has a recovery tank 721, a recovery pipe 722, and a recovery pump 723. The operation of the recovery pump 723 is controlled by a control signal output from the control device 500.

[0135] The recovery pipe 722 is connected to the first valve joint 240. The recovery pipe 722 is, for example, a hose. The recovery pump 723 sucks the cooling fluid 600 in the cooling tank 210 into the recovery pipe 722. The recovery pipe 722 is connected to the recovery tank 721. The recovery tank 721 stores the cooling fluid 600 discharged from the cooling tank 210. In this way, by connecting the battery module 200 and the cooling fluid recovery unit 720 via the first valve joint 240 and the recovery pipe 722, a recovery flow path 724 is formed, which is a cooling flow path through which the cooling fluid 600 can flow between the battery module 200 and the cooling fluid recovery unit 720.

[0136] Next, a description will be given of a method for cooling each battery cell 220 in this embodiment. The method for cooling each battery cell 220 while the eVTOL 100 is flying is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0137] After the eVTOL 100 lands, each battery module 200 mounted on the eVTOL 100 is connected to a cooling fluid supply unit 710 as shown in Figure 10. This forms a supply flow path 714 between the battery module 200 and the cooling fluid supply unit 710.

[0138] The control device 500 causes the supply pump 713 to cause the cooling fluid 600, which has been pre-cooled in the cooling fluid supply unit 710, to flow into the supply flow path 714. That is, the low-temperature cooling fluid 600 is caused to flow into the cooling tank 210 via the second valve joint 250. In this case, the supply pump 713 is controlled to pump the low-temperature cooling fluid 600 into the supply pipe 712. By causing the cooling fluid 600 to flow into the supply flow path 714 in this manner, each battery cell 220 inside the cooling tank 210 is rapidly cooled.

[0139] 11 , before the eVTOL 100 takes off, each battery module 200 mounted on the eVTOL 100 is removed from the cooling fluid supply unit 710 and connected to the cooling fluid recovery unit 720. This forms a recovery flow path 724 between the battery module 200 and the cooling fluid recovery unit 720.

[0140] The control device 500 causes the recovery pump 723 to discharge the cooling fluid 600 from the cooling tank 210 through the recovery flow path 724. That is, the cooling fluid 600 in the cooling tank 210 flows into the recovery tank 721 of the cooling fluid recovery unit 720 through the first valve joint 240. In this case, the recovery pump 723 is controlled to suck the cooling fluid 600 from the recovery pipe 722.

[0141] As described above, in the battery cooling system 300 of this embodiment, the cooling device 400 is provided separately from the cooling fluid supply unit 710 that supplies the cooling fluid 600 to the cooling tank 210, and the cooling fluid recovery unit 720 that recovers the cooling fluid 600 from the cooling tank 210. This allows the battery cells 220 to be efficiently cooled by repeatedly supplying low-temperature cooling fluid 600 to the cooling tank 210 and recovering high-temperature cooling fluid 600. Furthermore, a fluid cooling device for cooling the high-temperature cooling fluid 600 recovered from the cooling tank 210 can also be provided in a separate location.

[0142] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to the drawings. In the fourth embodiment, the shape of some of the heat storage tubes 230 included in the battery pack 260 is different from that in the first embodiment.

[0143] Here, of the multiple heat storage tubes 230 in the battery module 200, the heat storage tube 230 located in the center of the cell stacking direction is referred to as the central heat storage tube 230A, and the heat storage tubes 230 located on both ends of the cell stacking direction are referred to as the end heat storage tubes 230B.

[0144] 12, in the battery module 200 of this embodiment, the shape of the central heat storage tube 230A is different from the shape of the end-side heat storage tube 230B. As a result, the amount of heat storage material 231 in the central heat storage tube 230A is different from the amount of heat storage material 231 in the end-side heat storage tube 230B.

[0145] As an example, in the battery module 200 of this embodiment, the number of convex portions 233 of the central heat storage tube 230A is greater than the number of convex portions 233 of the end-side heat storage tube 230B. The amount of heat storage material 231 in the central heat storage tube 230A is greater than the amount of heat storage material 231 in the end-side heat storage tube 230B.

[0146] Generally, among the multiple battery cells 220 constituting the battery pack 260, the battery cells 220 located in the center of the cell stacking direction tend to trap heat and become hot. In contrast, in the battery module 200 of this embodiment, the amount of heat storage material 231 in the central heat storage tube 230A is greater than the amount of heat storage material 231 in the end-side heat storage tubes 230B. This ensures cooling performance for the battery cells 220 in the center of the cell stacking direction, which generate a large amount of heat, while reducing the amount of heat storage material 231 in the end-side heat storage tubes 230B, thereby achieving weight reduction and cost reduction.

[0147] Fifth Embodiment Next, a fifth embodiment of the present disclosure will be described with reference to the drawings. The fifth embodiment differs from the first embodiment in that fins 280 are provided in place of some of the heat storage tubes 230 included in the battery pack 260.

[0148] 13, the battery module 200 of this embodiment includes fins 280 arranged between adjacent battery cells 220. The fins 280 may be corrugated fins made by bending a metal sheet into a wave shape, or offset fins made by partially forming a plurality of cut-and-raised portions in a metal sheet.

[0149] As an example, in this embodiment, corrugated fins are used as the fins 280. That is, the fins 280 are formed to have a wave-like shape with top surface portions 281 and 282 alternately positioned on one side and the other side in the cell stacking direction.

[0150] Here, of the top surface portions 281, 282 of the fin 280, the one arranged on one side in the cell stacking direction is referred to as the first top surface portion 281, and the one arranged on the other side in the cell stacking direction is referred to as the second top surface portion 282. The fin 280 has a plurality of first top surface portions 281, a plurality of second top surface portions 282, and a plurality of side surface portions 283 connecting the first top surface portions 281 and the second top surface portions 282.

[0151] The first top surface portion 281 is in contact with the surface of the battery cell 220 on one side in the cell stacking direction of the adjacent battery cells 220. The second top surface portion 282 is in contact with the surface of the battery cell 220 on the other side in the cell stacking direction of the adjacent battery cells 220.

[0152] A gap 284 is formed between adjacent first top surface portions 281 and between adjacent second top surface portions 282. The gaps 284 define the cooling fluid passages 270. Therefore, the fins 280 of this embodiment correspond to an example of a flow passage forming portion.

[0153] More specifically, the cooling fluid passage 270 is formed by a gap 284 surrounded by a first top surface portion 281 of the fin 280, two side surfaces 283 connected to the first top surface portion 281, and the surface of the battery cell 220 facing the first top surface portion 281. The cooling fluid passage 270 is also formed by a gap 284 surrounded by a second top surface portion 282 of the fin 280, two side surfaces 283 connected to the second top surface portion 282, and the surface of the battery cell 220 facing the second top surface portion 282.

[0154] In this embodiment, the heat storage tubes 230 contact one surface of the battery cells 220 in the cell stacking direction, and the fins 280 contact the other surface of the battery cells 220 in the cell stacking direction. That is, in the battery pack 260, the heat storage tubes 230 and the fins 280 are arranged alternately one by one.

[0155] Note that louvers (not shown) may be provided on the side surface portions 283 of the fins 280. The louvers are formed by cutting and raising a part of the side surface portions 283. As a result, the louvers form communication holes that connect the front and back of the fins 280.

[0156] As described above, in the battery module 200 of this embodiment, the fins 280 are arranged between adjacent battery cells 220. The fins 280 have a buffering function (i.e., a spring function), and are therefore able to absorb volume changes due to the state of charge (SOC) of the battery cells 220, heat generation, and the like.

[0157] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described with reference to the drawings. The sixth embodiment differs from the fifth embodiment in the shape of the heat storage tubes 230 and the arrangement of the fins 280.

[0158] 14, in the battery module 200 of this embodiment, the outer shape of the heat storage tube 230 is formed in a rectangular parallelepiped shape. The surface of the heat storage tube 230 facing the battery cell 220 is formed in a flat shape perpendicular to the cell stacking direction.

[0159] In the battery module 200 of this embodiment, fins 280 are arranged between adjacent battery cells 220 and heat storage tubes 230. A first top surface portion 281 of the fin 280 is a cell-side connection portion that contacts the surface of the battery cell 220. A second top surface portion 282 of the fin 280 is a heat-storage-side connection portion that contacts the surface of the heat storage tube 230.

[0160] The surfaces of adjacent battery cells 220 and the surfaces of the heat storage tubes 230 are connected via fins 280. More specifically, the surfaces of adjacent battery cells 220 and the surfaces of the heat storage tubes 230 are connected via a plurality of first top surface portions 281 and a plurality of second top surface portions 282.

[0161] In this embodiment, the cooling fluid passage 270 is formed by a gap 284 surrounded by a first top surface portion 281 of the fin 280, two side surfaces 283 connected to the first top surface portion 281, and the surface of the heat storage tube 230 facing the first top surface portion 281. The cooling fluid passage 270 is also formed by a gap 284 surrounded by a second top surface portion 282 of the fin 280, two side surfaces 283 connected to the second top surface portion 282, and the surface of the battery cell 220 facing the second top surface portion 282.

[0162] Here, the first top surface portions 281 and second top surface portions 282 of the fins 280 in this embodiment correspond to an example of a connection portion. That is, the battery cells 220 and the heat storage tubes 230 are connected by the first top surface portions 281 and second top surface portions 282, which are connection portions. In the portions of the battery cells 220 and the heat storage tubes 230 that are not connected by the first top surface portions 281 and second top surface portions 282, gaps 284 are formed between the battery cells 220 and the heat storage tubes 230. The cooling fluid passages 270 are constituted by the gaps 284 formed between adjacent first top surface portions 281 and the gaps 284 formed between adjacent second top surface portions 282.

[0163] As described above, in the battery module 200 of this embodiment, the surfaces of adjacent battery cells 220 and the surfaces of the heat storage tubes 230 are connected via the fins 280, and the outer shape of the heat storage tubes 230 is formed into a rectangular parallelepiped shape. This simplifies the configuration of the heat storage tubes 230, and allows the fins 280 to absorb volume changes due to the state of charge (SOC) of the battery cells 220, heat generation, etc.

[0164] 15 , the surface of one side of the battery cell 220 in the cell stacking direction may be in direct contact with the heat storage tube 230 without the fin 280. In this case, the surface of the other side of the battery cell 220 in the cell stacking direction is in contact with the second top surface portion 282 of the fin 280.

[0165] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0166] (1) For example, in the above-described embodiment, an example was described in which the cooling fluid passage 270 is formed to penetrate in one direction and extend in the vertical direction, but the shape of the cooling fluid passage 270 is not limited to this form.

[0167] For example, the inlet portion 271 and the outlet portion 272 of the cooling fluid passage 270 may be provided at the same location. That is, the cooling fluid passage 270 may be formed so that the cooling fluid 600 makes a U-turn within the cooling fluid passage 270. Furthermore, the cooling fluid passage 270 may be formed so as to extend in a direction perpendicular to both the cell stacking direction and the top-to-bottom direction.

[0168] (2) In the above-described embodiment, an example has been described in which the control device 500 discharges all of the cooling fluid 600 from the cooling tank 210 before takeoff of the eVTOL 100, but this is not limiting. For example, the control device 500 may discharge a portion of the cooling fluid 600 from the cooling tank 210. In this way, when the cooling device 400 is removed from the valve joints 240, 250, the heat generated by each battery cell 220 can be absorbed and cooled not only by the heat storage material 231 of the heat storage tube 230 but also by the cooling fluid 600 remaining in the cooling tank 210.

[0169] (3) In the above-described embodiment, an example was described in which at least a portion of the cooling fluid 600 in the cooling tank 210 was discharged by the pump 440 through the cooling circulation circuit 460 before takeoff of the eVTOL 100, but the method of discharging the cooling fluid 600 is not limited to this. For example, by locating the tank 410 below the first valve joint 240, the cooling fluid 600 may be discharged from the cooling tank 210 toward the tank 410 by gravity.

[0170] (4) In the first embodiment described above, an example has been described in which one heat storage tube 230 is disposed between each pair of adjacent battery cells 220. However, the arrangement of the heat storage tubes 230 is not limited to this. For example, one heat storage tube 230 may be disposed adjacent to two battery cells 220 that are arranged in parallel. In this case, the heat storage tube 230 contacts one surface of the battery cell 220 in the cell stacking direction, and the heat storage tube 230 does not contact the surface of the battery cell 220 in the cell stacking direction.

[0171] (5) In the fifth embodiment described above, the amount of heat storage material 231 in the central heat storage tube 230A is greater than the amount of heat storage material 231 in the end heat storage tubes 230B. However, the amount of heat storage material 231 is not limited to this. For example, the amount of heat storage material 231 in the heat storage tubes 230 adjacent to each battery cell 220 may be optimized depending on the amount of heat generated by each battery cell 220. This allows for weight reduction and cost reduction.

[0172] (6) In addition, in the first to fifth embodiments described above, an example in which the heat storage tube 230 is provided with a plurality of protrusions 233 has been described, but the present invention is not limited to this. For example, the battery cell 220 may be provided with a protrusion that protrudes toward the heat storage tube 230.

[0173] The technical features of the battery module and battery cooling system disclosed in this specification are as follows: a heat storage section (230) disposed between adjacent battery cells, exchanging heat with the battery cells and storing heat from the battery cells; a valve fitting (240, 250) provided in the storage section, to which a cooling device (400) that supplies a cooling fluid (600) into the storage section is detachably attached; and a cooling fluid passage (270) provided between adjacent battery cells and the heat storage section, through which the cooling fluid supplied into the storage section can flow, wherein the battery cells and the heat storage section are connected by at least two connection sections (233, 281, 282), and a gap (235, 284) is formed between the battery cells and the heat storage section at a portion of the battery cells and the heat storage section that is not connected by the connection sections, and the cooling fluid passage is constituted by the gap formed between the adjacent connection sections. (Item 2) The battery module according to item 1, wherein the heat storage unit has a non-contact surface (234) that faces the battery cell and does not contact the battery cell, and a plurality of protrusions (233) that protrude from the non-contact surface toward the battery cell and contact the surface of the battery cell, the connection portion includes the protrusions, and the cooling fluid passage is configured by gaps (235) formed between adjacent protrusions. (Item 3) The battery module according to item 1, wherein a flow path forming member (280) is provided between the battery cell and the heat storage unit, the flow path forming member (280) having a plurality of cell-side connection portions (281) that contact the battery cell and a plurality of heat-storage-side connection portions (282) that contact the heat storage unit, the connection portions include the cell-side connection portions and the heat-storage-side connection portions, and the cooling fluid passage is configured by gaps (284) formed between adjacent cell-side connection portions and gaps (284) formed between adjacent heat-storage-side connection portions. (Item 4) The battery module according to any one of Items 1 to 3, wherein the cooling fluid is an insulating liquid having a boiling point lower than the heat resistance temperature of the battery cells.(Item 5) The battery module according to any one of Items 1 to 4, wherein the cooling fluid passage has an inlet (271) through which the cooling fluid flows into the cooling fluid passage and an outlet (272) through which the cooling fluid flows out of the cooling fluid passage, and the inlet and the outlet are provided at different positions. (Item 6) The battery module according to any one of Items 1 to 5, wherein the cooling fluid passage extends in the direction of gravity. (Item 7) A battery module (200) including: a plurality of battery cells (220); a storage section (210) that stores the plurality of battery cells; a heat storage section (230) that is disposed between adjacent battery cells and transfers heat between the battery cells and stores heat of the battery cells; a valve joint (240, 250) that is provided in the storage section and to which a cooling device (400) that supplies a cooling fluid (600) into the storage section is detachably attached; the cooling device that cools and stores the cooling fluid; and a control device (500) that controls the cooling device; and a cooling circulation circuit (460) that allows the cooling fluid to circulate between the battery module and the cooling device is configured by connecting the battery module and the cooling device via the valve joint. The control device circulates the cooling fluid, which has been pre-cooled by the cooling device, through the cooling circulation circuit, and after circulating the cooling fluid, discharges at least a portion of the cooling fluid in the storage section through the cooling circulation circuit.(Item 8) A battery module (200) including: a plurality of battery cells (220); a housing (210) that houses the plurality of battery cells; a heat storage section (230) that is arranged between adjacent battery cells and transfers heat between the battery cells and stores heat from the battery cells; a valve joint (240, 250) that is provided in the housing and to which a cooling device (400) that supplies a cooling fluid (600) into the housing is detachably attached; the cooling device (400) that cools and stores the cooling fluid; and a control device (500) that controls the cooling device; wherein the battery module and the cooling device are connected via the valve joint to form a cooling flow path (714, 724) through which the cooling fluid can flow between the battery module and the cooling device, The control device fills the cooling fluid, which has been pre-cooled in the cooling device, from the cooling device through the cooling flow path into the battery module, and after filling the cooling fluid, discharges at least a portion of the cooling fluid in the storage section through the cooling flow path.

[0174] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

a heat storage section (230) disposed between adjacent battery cells and configured to transfer heat between the battery cells and store heat of the battery cells; a valve fitting (240, 250) provided in the storage section to which a cooling device (400) that supplies a cooling fluid (600) into the storage section is detachably attached; and a cooling fluid passage (270) provided between adjacent battery cells and the heat storage section, through which the cooling fluid supplied to the storage section can flow, wherein the battery cells and the heat storage section are connected by at least two connection sections (233, 281, 282), and a gap (235, 284) is formed between the battery cells and the heat storage section in a portion of the battery cells and the heat storage section that is not connected by the connection sections, and the cooling fluid passage is configured by the gap formed between the adjacent connection sections.

2. A battery module as described in claim 1, wherein the heat storage portion has a non-contact surface (234) facing the battery cell and not in contact with the battery cell, and a plurality of protrusions (233) protruding from the non-contact surface toward the battery cell and in contact with the surface of the battery cell, the connection portion includes the protrusions, and the cooling fluid passage is constituted by gaps (235) formed between adjacent protrusions.

3. A battery module as described in claim 1, wherein a flow path forming member (280) having a plurality of cell side connection portions (281) in contact with the battery cells and a plurality of heat storage side connection portions (282) in contact with the heat storage portion is provided between the battery cells and the heat storage portion, the connection portions include the cell side connection portions and the heat storage side connection portions, and the cooling fluid passage is constituted by gaps (284) formed between adjacent cell side connection portions and gaps (284) formed between adjacent heat storage side connection portions.

4. A battery module according to any one of claims 1 to 3, wherein the cooling fluid is an insulating liquid having a boiling point lower than the heat resistance temperature of the battery cells.

5. A battery module as described in any one of claims 1 to 3, wherein the cooling fluid passage has an inlet portion (271) through which the cooling fluid flows into the cooling fluid passage and an outlet portion (272) through which the cooling fluid flows out of the cooling fluid passage, and the inlet portion and the outlet portion are provided in different locations.

6. The battery module according to any one of claims 1 to 3, wherein the cooling fluid passages extend in the direction of gravity.

7. A battery module (200) including: a plurality of battery cells (220); a storage section (210) for storing the plurality of battery cells; a heat storage section (230) arranged between adjacent battery cells, transferring heat between the battery cells and storing heat of the battery cells; a valve joint (240, 250) provided in the storage section to which a cooling device (400) for supplying a cooling fluid (600) into the storage section is detachably attached; the cooling device for cooling and storing the cooling fluid; and a control device (500) for controlling the cooling device; wherein the battery module and the cooling device are connected via the valve joint to form a cooling circulation circuit (460) capable of circulating the cooling fluid between the battery module and the cooling device; The control device circulates the cooling fluid, which has been pre-cooled in the cooling device, through the cooling circulation circuit, and after circulating the cooling fluid, discharges at least a portion of the cooling fluid in the storage section through the cooling circulation circuit.

8. A battery module (200) including: a plurality of battery cells (220); a storage section (210) for storing the plurality of battery cells; a heat storage section (230) arranged between adjacent battery cells, transferring heat between the battery cells and storing heat of the battery cells; a valve joint (240, 250) provided in the storage section to which a cooling device (400) for supplying a cooling fluid (600) into the storage section is detachably attached; the cooling device (400) for cooling and storing the cooling fluid; and a control device (500) for controlling the cooling device, wherein the battery module and the cooling device are connected via the valve joint to form a cooling flow path (714, 724) through which the cooling fluid can flow between the battery module and the cooling device, The control device is a battery cooling system that fills the cooling fluid, which has been pre-cooled in the cooling device, from the cooling device through the cooling flow path into the battery module, and after filling the cooling fluid, discharges at least a portion of the cooling fluid in the storage section through the cooling flow path.

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