Cooling system

Abstract

The present invention discloses a cooling system (60). The cooling system (60) includes a rotor (a VTOL rotor (20) or a cruise rotor (22)), a component group (24), and a cooling circuit (62). The rotor generates at least one of lift and thrust of an aircraft (10); the component group (24) is composed of a plurality of electrical components that rotate the rotor; and the cooling circuit (62) cools the component group (24). The cooling system (60) includes a plurality of component groups (24) corresponding to the plurality of rotors, and the plurality of component groups (24) are cooled by the same cooling circuit (62). Accordingly, a cooling system provided in an aircraft becomes simple and lightweight.

Description

Technical Field

[0001] The present invention relates to a cooling system for cooling electrical components used to rotate a rotor of an aircraft. Background Art

[0002] The specification of U.S. Patent Application Publication No. 2020 / 0115045 shows an aircraft called an electric vertical take-off and landing aircraft (eVTOL aircraft). The aircraft has multiple rotors for take-off and landing (called VTOL rotors) and multiple rotors for cruising (called cruise rotors). Each rotor is connected to an electric motor. The electric motor is connected to a power supply through a drive circuit (inverter, etc.). The electric motor and the drive circuit generate heat as electric power is supplied. The specification of U.S. Patent Application Publication No. 2020 / 0115045 discloses cooling the electric motor by air cooling. In addition, the specification of U.S. Patent Application Publication No. 2020 / 0115045 discloses that air cooling is superior to liquid cooling in terms of system simplification and lightweighting. Summary of the Invention

[0003] U.S. Patent Application Publication No. 2020 / 0115045 does not disclose a cooling structure for the electric motor's drive circuit. Furthermore, liquid-cooled electric motors have a higher power density than air-cooled ones. Therefore, liquid-cooled electric motors are preferred when high power is required. Furthermore, air cooling has a lower cooling capacity than liquid cooling, and therefore may not adequately cool electrical components such as the electric motor and drive circuit. Therefore, liquid cooling is preferred to adequately cool electrical components.

[0004] However, as disclosed in U.S. Patent Application Publication No. 2020 / 0115045, liquid cooling presents challenges of complexity and weight. For example, a single rotor is equipped with an electric motor and drive circuit. If a cooling circuit is established for each motor and drive circuit, piping and components (radiators, pumps, etc.) corresponding to the number of rotors are required, making the cooling system complex and heavy.

[0005] The purpose of the present invention is to solve the above-mentioned technical problems.

[0006] The present invention is directed to a cooling system comprising a rotor, a component group, and a cooling circuit, wherein:

[0007] The rotor generates at least one of lift and thrust for the aircraft;

[0008] The component group is composed of a plurality of electrical components that cause the rotor to rotate;

[0009] The cooling circuit cools the plurality of electrical components.

[0010] The cooling system has a plurality of component groups corresponding to a plurality of the rotors.

[0011] A plurality of the component groups are cooled by the same cooling circuit.

[0012] According to the present invention, the cooling system provided in the aircraft becomes simple and lightweight.

[0013] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of an aircraft viewed from above.

[0015] Figure 2 This diagram shows the arrangement of each rotor and each component group in the electric power supply system.

[0016] Figure 3 This is a diagram showing a circuit of an electric power supply system.

[0017] Figure 4 This is a diagram showing a control block of an electric power supply system.

[0018] Figure 5 This graph shows the flight time after takeoff, the inverter's input power, and the amount of heat dissipated per unit gas-liquid temperature difference.

[0019] Figure 6 This diagram shows the changes in the main body that generates lift as the flight state changes.

[0020] Figure 7 This diagram shows the arrangement of each rotor and each component group in the electric power supply system.

[0021] Figure 8 This is a diagram showing a circuit of an electric power supply system.

[0022] Figure 9 It is a diagram showing a circuit of the cooling system. DETAILED DESCRIPTION

[0023] [1 Structure of Aircraft 10]

[0024] use Figure 1 The structure of the aircraft 10 is described below. In this embodiment, the aircraft 10 is assumed to be an electric vertical take-off and landing aircraft (eVTOL aircraft). The electric vertical take-off and landing aircraft generates lift and thrust through multiple rotors. The driving source of each rotor is an electric motor 26 ( Figure 2). In addition, in this embodiment, it is assumed that the aircraft 10 is a hybrid aircraft. The hybrid aircraft can be powered by the battery 32 ( Figure 2 ) to operate the electric motor 26. In addition, the hybrid aircraft can be powered by the electric power supplied from the motor generator 42 ( Figure 3 ) to operate the electric motor 26. In addition, the hybrid aircraft can charge the battery 32.

[0025] Aircraft 10 has a fuselage 12 , a front wing 14 , a rear wing 16 , two booms 18 , eight VTOL rotors 20 , and two cruise rotors 22 .

[0026] A front wing 14 is connected to the front portion of the fuselage 12. The front wing 14 generates lift when the aircraft 10 moves forward. A rear wing 16 is connected to the rear portion of the fuselage 12. The rear wing 16 generates lift when the aircraft 10 moves forward.

[0027] The two booms 18 include a right boom 18R and a left boom 18L. The right boom 18R is located on the right side of the fuselage 12. The left boom 18L is located on the left side of the fuselage 12. The two booms 18 are connected to the front wing 14 and the rear wing 16. The two booms 18 are connected to the fuselage 12 via the front wing 14 and the rear wing 16. The booms 18R and 18L each support four VTOL rotors 20.

[0028] Each VTOL rotor 20 is used when the aircraft 10 takes off vertically, transitions from vertical takeoff to cruise control, transitions from cruise control to vertical landing, vertically lands, and stops flying. The rotation axis of each VTOL rotor 20 is arranged parallel to the vertical direction. Each VTOL rotor 20 rotates about the rotation axis to generate lift.

[0029] The eight VTOL rotors 20 are composed of four VTOL rotors 20Ra to 20Rd located on the right side of the fuselage 12, and four VTOL rotors 20La to 20Ld located on the left side of the fuselage 12. The right VTOL rotors 20Ra to 20Rd are supported by the boom 18R. The right VTOL rotors 20Ra to 20Rd are arranged in the order of VTOL rotor 20Ra, VTOL rotor 20Rb, VTOL rotor 20Rc, and VTOL rotor 20Rd from front to back. The left VTOL rotors 20La to 20Ld are supported by the boom 18L. The left VTOL rotors 20La to 20Ld are arranged in the order of VTOL rotor 20La, VTOL rotor 20Lb, VTOL rotor 20Lc, and VTOL rotor 20Ld from front to back. The right VTOL rotors 20Ra to 20Rd and the left VTOL rotors 20La to 20Ld are arranged bilaterally symmetrically about a vertical plane including the central axis A of the fuselage 12. Alternatively, the right VTOL rotors 20Ra to 20Rd and the left VTOL rotors 20La to 20Ld may be arranged point-symmetrically (centrally symmetrically) about the center of gravity G of the fuselage.

[0030] Each cruise rotor 22 is used when the aircraft 10 is cruising, transitioning from vertical takeoff to cruise, and transitioning from cruise to vertical landing. The rotation axis of each cruise rotor 22 is arranged parallel to the front-rear direction. Each cruise rotor 22 generates thrust by rotating about the rotation axis.

[0031] The two cruise rotors 22 are composed of a cruise rotor 22R arranged on the right side of the fuselage 12 and a cruise rotor 22L arranged on the left side of the fuselage 12. The two cruise rotors 22 are supported by the fuselage 12. The two cruise rotors 22 are arranged bilaterally symmetrically about a vertical plane including the central axis A of the fuselage 12.

[0032] The aircraft 10 has a drive mechanism (not shown) and an electric power supply system 23 ( Figure 2 and Figure 3 The drive mechanism and the electric power supply system 23 rotate the VTOL rotors 20 and the cruise rotors 22. In addition, the aircraft 10 has a cooling system 60 ( Figure 9 The cooling system 60 cools the various electrical components included in the electric power supply system 23 .

[0033] [2. Structure of the Electric Power Supply System 23]

[0034] use Figure 2 and Figure 3 The structure of the electric power supply system 23 is described below. Figure 2As shown, one assembly group 24 is provided for each VTOL rotor 20 , and two assembly groups 24 are provided for each cruise rotor 22 . Figure 2 and Figure 3 The illustrated electric power supply system 23 includes twelve component groups 24. Furthermore, the electric power supply system 23 comprises four groups (first group G1 to fourth group G4). Each group includes three component groups 24 and a battery 32. Each component group 24 includes multiple electrical components, here including an electric motor 26, an inverter 28 (INV), and a first smoothing capacitor 30. The electric motor 26 is connected to the battery 32 via the inverter 28 and the first smoothing capacitor 30.

[0035] The electric motor 26 is a three-phase motor. The output shaft of the electric motor 26 is connected to the rotating shaft of the corresponding rotor (VTOL rotor 20 or cruise rotor 22). The inverter 28 has multiple switching elements such as IGBTs. The primary side terminals of the inverter 28 are connected to the first smoothing capacitor 30 and the battery 32. The secondary side terminals of the inverter 28 are connected to the electric motor 26. The inverter 28 converts the DC power input to the primary side terminals into three-phase AC power and outputs it from the secondary side terminals. According to the above structure, each electric motor 26 is operated by the electric power supplied from the battery 32.

[0036] like Figure 3 As shown, the primary-side terminals of the inverter 28, the first smoothing capacitor 30, and the batteries 32 (32a to 32d) are connected to the motor generator 42 via the switch 36, the second smoothing capacitor 38, and the power control unit 40 (PCU 40).

[0037] The motor generator 42 functions as a three-phase motor and also as a three-phase generator. The rotating shaft of the motor generator 42 is connected to the output shaft of the engine 44 (ENG). The PCU 40 includes an inverter circuit. The primary-side terminal of the PCU 40 is connected to the motor generator 42. The secondary-side terminal of the PCU 40 is connected to the second smoothing capacitor 38. Furthermore, the secondary-side terminal of the PCU 40 is connected to the battery 32 and the primary-side terminal of the inverter 28 via the switch 36. The PCU 40 converts the three-phase AC power input to the primary-side terminal into DC power using the inverter circuit. The PCU 40 outputs the converted DC power from the secondary-side terminal. Furthermore, the PCU 40 converts the DC power input to the secondary-side terminal into three-phase AC power using the inverter circuit. The PCU 40 outputs the three-phase AC power from the primary-side terminal. The switch 36 includes switching elements such as IGBTs and diodes. Switch 36 always allows electric power to be supplied from PCU 40 to battery 32, and when turned on, allows electric power to be supplied from battery 32 to PCU 40. With the above configuration, motor generator 42 can output generated electric power to battery 32 and inverter 28. Furthermore, when switch 36 is turned on, motor generator 42 operates using electric power supplied from battery 32. When electric power is supplied to motor generator 42, engine 44 starts. Engine 44 can use a well-known internal combustion engine such as a reciprocating engine or a gas turbine engine. PCU 40 may also include a DC / DC converter circuit.

[0038] in addition, Figure 2 and Figure 3 The power supply system 23 is shown in simplified form. The power supply system 23 also includes other electrical components. Examples of electrical components not shown include electrical loads other than the electric motor 26, resistors, coils, capacitors, various sensors, fuses, relays, and circuit breakers.

[0039] like Figure 4 As shown, a controller 48 is provided in the aircraft 10. The controller 48 comprises, for example, a processor such as a CPU, or an integrated circuit such as an ASIC or FPGA. For example, the processor implements various functions by executing programs stored in memory. The controller 48 outputs control signals to the switching elements of each inverter 28, each switch 36, and the power control unit 40, thereby controlling the operation of each switching element.

[0040] [3. Operation of the Electric Power Supply System 23]

[0041] use Figure 2 and Figure 3The operation of the electric power supply system 23 will be described below. When the aircraft 10 is started, the controller 48 turns on at least one switch 36 in response to an operator's operation. Furthermore, the controller 48 controls the operation of the various switching elements of the PCU 40 in response to the operator's operation. This then supplies electric power from at least one battery 32 (32a-32d) to the motor generator 42 via the PCU 40. The PCU 40 converts the DC power supplied from the battery 32 into AC power and outputs it to the motor generator 42. The motor generator 42 operates with the supplied electric power, starting the engine 44.

[0042] After the engine 44 is started, the motor generator 42 generates electricity through the operation of the engine 44. In this state, electric power can be supplied from the motor generator 42 to the battery 32 and module group 24 of each group via the PCU 40. The PCU 40 converts the AC power generated by the motor generator 42 into DC power and outputs it to each battery 32 and module group 24. The inverter 28 converts the DC power output from the PCU 40 or the DC power supplied from the battery 32 into AC power and outputs it to the electric motor 26. The electric motor 26 is operated by the supplied electric power, rotating the rotor (VTOL rotor 20 or cruise rotor 22).

[0043] When the electric motor 26 is rotated by the power of the battery 32, the switching elements of each switch 36 are basically in the off state. Therefore, electric power is not supplied from the battery 32 of one group to the module group 24 of another group. However, it is possible to supply electric power from the battery 32 of one group to the module group 24 of another group by turning on the switching elements of the switch 36.

[0044] [An example of grouping four module groups 24 and batteries 32]

[0045] like Figure 2 and Figure 3 As shown, in the power supply system 23, multiple module groups 24 and multiple batteries 32 are divided into four groups (first group G1 to fourth group G4), each consisting of three module groups 24 and one battery 32. Multiple module groups 24 within a group receive power from a single battery 32 within the same group. A single battery 32 is comprised of one battery module or multiple battery modules. Each battery 32 in a group is independent of the batteries 32 in other groups.

[0046] The first group G1 includes a component group 24Ra corresponding to the VTOL rotor 20Ra, a component group 24Ld corresponding to the VTOL rotor 20Ld, a component group 24R1 corresponding to the cruise rotor 22R, and a battery 32a. The electrical components of the first group G1 are connected by wiring 34a.

[0047] The second group G2 includes a component group 24La corresponding to the VTOL rotor 20La, a component group 24Rd corresponding to the VTOL rotor 20Rd, a component group 24L1 corresponding to the cruise rotor 22L, and a battery 32b. The electrical components of the second group G2 are connected by wiring 34b.

[0048] The third group G3 includes a component group 24Rb corresponding to the VTOL rotor 20Rb, a component group 24Lc corresponding to the VTOL rotor 20Lc, a component group 24R2 corresponding to the cruise rotor 22R, and a battery 32c. The electrical components of the third group G3 are connected by wiring 34c.

[0049] The fourth group G4 includes a component group 24Lb corresponding to the VTOL rotor 20Lb, a component group 24Rc corresponding to the VTOL rotor 20Rc, a component group 24L2 corresponding to the cruise rotor 22L, and a battery 32d. The electrical components of the fourth group G4 are connected by wiring 34d.

[0050] For redundancy, the electric motors 26 of assembly group 24R1 and the electric motors 26 of assembly group 24R2 are connected to the same cruise rotor 22R. Normally, both assembly groups 24R1 and 24R2 are used to rotate cruise rotor 22R. Furthermore, if one assembly group 24 fails, the other assembly group 24 is used to rotate cruise rotor 22R. Similarly, the electric motors 26 of assembly group 24L1 and the electric motors 26 of assembly group 24L2 are connected to the same cruise rotor 22L.

[0051] [4.1 Reasons for grouping (1)]

[0052] To reduce the number of batteries 32, it is conceivable to share a single battery 32 for all module groups 24. However, this would create other problems, such as requiring a large-capacity battery 32. Therefore, it is preferable to provide multiple batteries 32. Furthermore, it is preferable to efficiently combine the module groups 24 and batteries 32. In this embodiment, the multiple module groups 24 and the multiple batteries 32 are divided into four groups (first group G1 to fourth group G4) for the following reasons.

[0053] like Figure 1As shown, in this embodiment, the two VTOL rotors 20, which are arranged at positions symmetrical to each other about the center of gravity G, rotate in opposite directions. For example, the right VTOL rotor 20Ra rotates in the direction R1. This rotation direction is opposite to the rotation direction (R2) of the left VTOL rotor 20Ld, which forms a pair with the VTOL rotor 20Ra. Furthermore, the left VTOL rotor 20La rotates in the direction R2. This rotation direction is opposite to the rotation direction (R1) of the right VTOL rotor 20Rd, which forms a pair with the VTOL rotor 20La. Furthermore, the right VTOL rotor 20Rb rotates in the direction R2. This rotation direction is opposite to the rotation direction (R1) of the left VTOL rotor 20Lc, which forms a pair with the VTOL rotor 20Rb. Furthermore, the left VTOL rotor 20Lb rotates in the direction R1. This rotation direction is opposite to the rotation direction (R2) of the right VTOL rotor 20Rc, which forms a pair with the VTOL rotor 20Lb.

[0054] When the VTOL rotor 20 rotates, thrust and reaction force (torque reaction force) are generated by the rotor blades. As described above, by rotating the two VTOL rotors 20 constituting a pair in opposite directions, the reaction force generated on the aircraft body can be offset.

[0055] For example, when the electric power system or mechanical system associated with one VTOL rotor 20 fails, the VTOL rotor 20 stops. In this case, when the other VTOL rotor 20 forming a pair with the stopped VTOL rotor 20 continues to rotate, the reaction force generated by the other VTOL rotor 20 is not offset and acts on the fuselage. As a result, a yaw moment is generated on the fuselage. In addition, when the other VTOL rotor 20 forming a pair with the stopped VTOL rotor 20 continues to rotate, the balance of the thrust of the left and right VTOL rotors 20 is destroyed. As a result, a roll moment and a pitch moment are generated on the fuselage. To avoid this situation, when one VTOL rotor 20 forming a pair stops due to a failure, etc., it is necessary to stop the other VTOL rotor 20. In this way, the yaw moment caused by the destruction of the balance of the reaction force (torque reaction force) can be suppressed. In addition, the roll moment and the pitch moment generated by the destruction of the balance of the thrust can be suppressed.

[0056] Therefore, when multiple module groups 24 share a battery 32, it is more efficient to share the battery 32 between the two module groups 24 corresponding to the two VTOL rotors 20 forming a pair. Therefore, in this embodiment, the two module groups 24 and one battery 32 corresponding to the two VTOL rotors 20 forming a pair are grouped together.

[0057] In addition, the two VTOL rotors 20 that cancel each other's reaction forces may also be a combination different from the above examples. For example, two VTOL rotors 20 adjacent to each other on the left and right may form a pair, like the VTOL rotor 20Ra and the VTOL rotor 20La. In addition, two VTOL rotors 20 arranged in front and behind with one VTOL rotor 20 between them may form a pair, like the VTOL rotor 20Ra and the VTOL rotor 20Rc. In addition, two VTOL rotors 20 with opposite rotation directions may form a pair. In addition, based on the above ideas, Figure 1 The combination of rotors constituting a pair is also set by setting the rotation direction of each rotor other than the VTOL rotor 20 shown.

[0058] [4.2 Reasons for grouping (2)]

[0059] Figure 5 The horizontal axis shown is the flight time [s] of the aircraft 10 . Figure 5 The vertical axis shows the electric power (W) input to the inverter 28 from the battery 32 or the electric generator 42 and the heat dissipation per unit gas-liquid temperature difference (W / K). The heat dissipation per unit gas-liquid temperature difference is defined as heat dissipation / (refrigerant temperature - outside air temperature). Furthermore, the heat dissipation per unit gas-liquid temperature difference is correlated with the heat generation (W) of the inverter 28 (and the electric motor 26). The transitions in the heat dissipation per unit gas-liquid temperature difference and the heat generation (W) of the inverter 28 (and the electric motor 26) can have the same characteristics as the fourth transition 56 described below.

[0060] exist Figure 5 , three changes in electric power over time are shown as first to third transitions 50 to 54. Figure 5 The change in thermal resistance over time is shown in FIG. 5 as the fourth transition 56. The first transition 50 represents the change in the input electric power of the two inverters 28 corresponding to the two VTOL rotors 20. The two VTOL rotors 20 refer to the two VTOL rotors 20 that constitute a pair (see [4.1] above). The second transition 52 represents the change in the input electric power of one inverter 28 corresponding to one cruise rotor 22. The third transition 54 represents the change in the total value of the input electric power of the first transition 50 and the input electric power of the second transition 52. The fourth transition 56 represents the change in the value obtained by converting the electric power of the third transition 54 into the heat dissipation (heat generation) per unit gas-liquid temperature difference.

[0061] The flight state from time t1 to time t2 is vertical takeoff. During this time period, the VTOL rotor 20 is primarily used, and the cruise rotor 22 is not. Therefore, as shown by the first transition 50, the input power to the inverter 28 corresponding to the VTOL rotor 20 is high. On the other hand, as shown by the second transition 52, the input power to the inverter 28 corresponding to the cruise rotor 22 is low.

[0062] The flight state from time t2 to time t3 transitions from vertical takeoff to cruise. During this period, the utilization rate of the VTOL rotor 20 gradually decreases, while the utilization rate of the cruise rotor 22 gradually increases. Therefore, as shown by the first transition 50, the input power to the inverter 28 corresponding to the VTOL rotor 20 gradually decreases. On the other hand, as shown by the second transition 52, the input power to the inverter 28 corresponding to the cruise rotor 22 gradually increases.

[0063] The flight state after time t3 is cruise. During this time period, the cruise rotor 22 is primarily used, while the VTOL rotor 20 is not used or is used only slightly. Therefore, as shown by the second transition 52, the input power to the inverter 28 corresponding to the cruise rotor 22 is large. On the other hand, as shown by the first transition 50, the input power to the inverter 28 corresponding to the VTOL rotor 20 is small.

[0064] Furthermore, the performance of cooling system 60 is proportional to the difference between the refrigerant liquid temperature and the outside air temperature. As the aircraft 10's altitude increases and the outside air temperature decreases, the cooling capacity of cooling system 60 increases. Specifically, the cooling capacity of cooling system 60 can be increased at time t2 and later compared to time t1.

[0065] In addition, if Figure 6 As shown, the lift required for vertical takeoff is obtained by the rotation of the VTOL rotor 20 (rotor lift). On the other hand, the lift required for transitioning from vertical takeoff to cruising is obtained by the rotation of the VTOL rotor 20 and is obtained by the wings (front wing 14 and rear wing 16). The lift obtained by the wings (wing lift) increases as the moving speed increases. The lift required for cruising is obtained by the wings. During vertical takeoff (and vertical landing) in which lift is generated by the rotation of the VTOL rotor 20, the input electrical power of the inverter 28 corresponding to the VTOL rotor 20 is large. On the other hand, during cruising in which lift is generated by the wings, the input electrical power of the inverter 28 corresponding to the VTOL rotor 20 is relatively small.

[0066] During the period from takeoff to cruising (time t1 to time t3) and during the period of cruising (after time t3), the maximum value of the third transition 54 does not differ significantly from the maximum values ​​of the first transition 50 and the maximum value of the second transition 52. In other words, the two assembly groups 24 corresponding to the two VTOL rotors 20 and the one assembly group 24 corresponding to the one cruise rotor 22 can share one battery 32. Therefore, in this embodiment, the two assembly groups 24 corresponding to the two VTOL rotors 20 forming a pair, the one assembly group 24 corresponding to the one cruise rotor 22, and the one battery 32 are grouped together.

[0067] [4.3 Method of Assembling the Component Group 24 of the Cruise Rotor 22]

[0068] Each group is composed of two assembly groups 24 corresponding to the two VTOL rotors 20 forming a pair, and an assembly group 24 corresponding to a single cruise rotor 22. One cruise rotor 22 is provided on each side. The following considerations determine which of the assembly groups 24R1 and 24R2 corresponding to the cruise rotor 22R and the assembly groups 24L1 and 24L2 corresponding to the cruise rotor 22L to combine in each group.

[0069] The difference between the length from one of the two VTOL rotors 20 forming a pair to the right cruise rotor 22R and the length from the other VTOL rotor 20 to the right cruise rotor 22R is D1. Furthermore, the difference between the length from one VTOL rotor 20 to the left cruise rotor 22L and the length from the other VTOL rotor 20 to the left cruise rotor 22L is D2. A combination with the smallest difference is used in each group.

[0070] For example, let's take the first group G1 as an example. Let D1 be the difference between the length from the VTOL rotor 20Ra to the right cruise rotor 22R and the length from the VTOL rotor 20Ld to the right cruise rotor 22R. On the other hand, let D2 be the difference between the length from the VTOL rotor 20Ra to the left cruise rotor 22L and the length from the VTOL rotor 20Ld to the left cruise rotor 22L. D1 is smaller than D2. Therefore, the first group G1 includes a combination of the component group 24Ra, the component group 24Ld, and the component group 24R1. The same applies to the other groups. Consequently, the deviation in the distance between two component groups 24 within the same group is reduced.

[0071] [4.4 Location of Battery 32]

[0072] The batteries 32 are arranged so that the length of the wiring 34 is minimized. For example, let's take the first group G1 as an example. Let's assume that the length of the wiring 34a from the electric motor 26 that rotates one VTOL rotor 20Ra to the battery 32a is L1. Let's assume that the length of the wiring 34a from the electric motor 26 that rotates the other VTOL rotor 20Ld to the battery 32a is L2. Let's assume that the length of the wiring 34a from the electric motor 26 that rotates the cruise rotor 22R to the battery 32a is L3. In this case, the batteries 32a are arranged so that the total length (L1 + L2 + L3) is minimized.

[0073] [Other Examples of Grouping 5 Module Groups 24 and Batteries 32]

[0074] Can also be carried out with Figure 2 and Figure 3 The examples shown are different from the grouping. For example, it is also possible to Figure 7 and Figure 8 In this example, multiple module groups 24 and multiple batteries 32 are divided into first to fourth groups G1 to G4. The first group G1 and the second group G2 include four module groups 24 and one battery 32. The third group G3 and the fourth group G4 include two module groups 24 and one battery 32.

[0075] Can also be carried out with Figure 7 and Figure 8 The example shown is different from the grouping. For example, one component group 24 corresponding to a VTOL rotor 20, one component group 24 corresponding to one cruise rotor 22, and one battery 32 may be grouped together in the same group.

[0076] [6. Structure of Cooling System 60]

[0077] use Figure 9 The structure of the cooling system 60 is described below. In this embodiment, an independent cooling system 60 is provided for each group of the electric power supply system 23. Figure 2 and Figure 3 Four independent cooling systems 60 are provided in the illustrated electrical power supply system 23 . Figure 9 Show Figure 2 and Figure 3 The cooling system 60 of the first group G1 is shown.

[0078] Cooling system 60 is a liquid-cooled system with higher cooling capacity than air-cooled systems. It includes a cooling circuit 62. Cooling circuit 62 includes a radiator 66 and three pumps (first pump 68a through third pump 68c) on piping 64 through which the refrigerant flows. Cooling circuit 62 is a closed circuit. The refrigerant is liquid.

[0079] The pipe 64 includes three parallel pipes 70a, 70b, and 70c connected in parallel to each other and a common pipe 72. The common pipe 72 connects the upstream and downstream sides of the parallel pipes 70a, 70b, and 70c. The radiator 66 is provided on the common pipe 72.

[0080] The parallel piping 70a is configured to cool the component group 24Ra (e.g., the electric motor 26 and the inverter 28) corresponding to the VTOL rotor 20Ra. The parallel piping 70a may also be configured to cool other electrical components in the component group 24Ra. A first pump 68a is provided upstream of the component group 24Ra on the parallel piping 70a.

[0081] The parallel piping 70b is configured to cool the component group 24Ld (e.g., the electric motor 26 and the inverter 28) corresponding to the VTOL rotor 20Ld. The parallel piping 70b may also be configured to cool other electrical components in the component group 24Ld. A second pump 68b is provided upstream of the component group 24Ld on the parallel piping 70b.

[0082] The parallel piping 70c is configured to cool the component group 24R1 corresponding to the cruise rotor 22R (e.g., the electric motor 26 and the inverter 28). The parallel piping 70c may also be configured to cool other electrical components in the component group 24R1. A third pump 68c is provided upstream of the component group 24R1 on the parallel piping 70c.

[0083] In addition, Figure 9 In the cooling circuit 62 shown, pumps (first to third pumps 68a to 68c) are provided on the parallel pipes 70a, 70b, and 70c, respectively. Alternatively, a common pump may be provided on the common pipe 72.

[0084] like Figure 5As shown, during the period from takeoff to cruising (time t1 to time t3) and during the period of cruising (after time t3), the maximum value of the third transition 54 is not significantly different from the maximum values ​​of the first transition 50 and the maximum value of the second transition 52. This means that the maximum value of the fourth transition 56 is not significantly different from the maximum value of the heat generated by the two assembly groups 24 corresponding to the two VTOL rotors 20 and the maximum value of the heat generated by the one assembly group 24 corresponding to the one cruise rotor 22. In other words, the two assembly groups 24 corresponding to the two VTOL rotors 20 and the one assembly group 24 corresponding to the one cruise rotor 22 can share a single cooling circuit 62. Therefore, in this embodiment, the two assembly groups 24 corresponding to the two VTOL rotors 20 forming a pair and the one assembly group 24 corresponding to the one cruise rotor 22 are cooled collectively by the same cooling circuit 62. Furthermore, the cooling circuit 62 can also be used to cool the battery 32a.

[0085] [7 Operation of Cooling System 60]

[0086] use Figure 9 The operation of the cooling system 60 will be described below. When the first pump 68a is operating, the refrigerant circulates through the parallel pipe 70a and the common pipe 72. When the second pump 68b is operating, the refrigerant circulates through the parallel pipe 70b and the common pipe 72. When the third pump 68c is operating, the refrigerant circulates through the parallel pipe 70c and the common pipe 72. The refrigerant absorbs heat from each electrical component of each module group 24 and dissipates the heat through the radiator 66. In this way, each electrical component is cooled.

[0087] As described in [4.3] above, within the same group, the distance between two component groups 24 varies little. Consequently, the lengths of the parallel pipes 70a, 70b, and 70c within the same group vary little. Therefore, by arranging the radiator 66 in an appropriate position, the difference in pressure drop of the refrigerant flowing through the parallel pipes 70a, 70b, and 70c can be reduced, thereby reducing the difference in discharge head of the first pump 68a to the third pump 68c.

[0088] [8 Other embodiments]

[0089] In the above embodiment, the electric power supply system 23 and the cooling system 60 are described using an aircraft 10 having eight VTOL rotors 20 and two cruise rotors 22 as an example. However, the electric power supply system 23 and the cooling system 60 can also be provided in other aircraft 10 having a different number of rotors. For example, the electric power supply system 23 and the cooling system 60 can also be provided in an aircraft 10 having more than two VTOL rotors 20. In this case, the two component groups 24 and the battery 32 corresponding to the two VTOL rotors 20 forming a pair can also be grouped together. In addition, when the aircraft 10 has cruise rotors 22, the one or more component groups 24 corresponding to the one or more VTOL rotors 20 and the component group 24 and the battery 32 corresponding to the cruise rotor 22 can also be grouped together.

[0090] The electric power supply system 23 may also be Figure 3 and Figure 8 In short, the components 24 may be combined in the above-mentioned combinations, and the circuit of the electric power supply system 23 is arbitrary.

[0091] In addition, the present invention is applicable not only to a hybrid aircraft having an engine 44 and an electric generator 42, but also to an electric aircraft not having an engine 44 and an electric generator 42. Figure 3 and Figure 8 In the circuit shown, the second smoothing capacitor 38 to the motor 44 may not exist. In this case, by switching each switch 36 as needed, electric power can be supplied from one group of batteries 32 to another group. As another example, in Figure 3 and Figure 8 In the circuit shown, the components from the second smoothing capacitor 38 to the motor 44 and the switches 36 of each group may not exist. In this case, the groups are insulated from each other.

[0092] The electric power supply system 23 and the cooling system 60 of the above-described embodiment may also be provided for an aircraft 10 having a tilt-rotor.

[0093] [9 Technical Concepts Obtainable from Implementation Methods]

[0094] The following describes the technical ideas that can be grasped from the above-mentioned embodiments.

[0095] The present invention is directed to a cooling system 60 comprising a rotor (VTOL rotor 20, cruise rotor 22), a component group 24, and a cooling circuit 62, wherein:

[0096] The rotor generates at least one of lift and thrust of the aircraft 10;

[0097] The component group 24 is composed of a plurality of electrical components that cause the rotor to rotate;

[0098] The cooling circuit 62 cools the plurality of electrical components.

[0099] The cooling system 60 has a plurality of component groups 24 corresponding to a plurality of the rotors.

[0100] A plurality of the component groups 24 are cooled by the same cooling circuit 62 .

[0101] According to the above configuration, the multiple component groups 24 are cooled by the same cooling circuit 62, eliminating the need for a separate cooling circuit 62 for each component group 24. Specifically, according to the above configuration, the components of the cooling circuit 62 (such as the piping 64 and the radiator 66) are shared by the multiple component groups 24. Therefore, according to the above configuration, the number of components in the cooling system 60 provided in the aircraft 10 can be reduced. As a result, the cooling system 60 provided in the aircraft 10 becomes simpler and lighter.

[0102] In the embodiment of the present invention, it is also possible to

[0103] The rotor includes a VTOL rotor 20 and a cruise rotor 22 , wherein the VTOL rotor 20 generates lift when the aircraft 10 moves in a vertical direction; and the cruise rotor 22 generates thrust when the aircraft 10 moves in a horizontal direction.

[0104] The component group 24 includes a VTOL component group (for example, the component group 24Ra) corresponding to the VTOL rotor 20 and a cruise component group (for example, the component group 24R1) corresponding to the cruise rotor 22.

[0105] The VTOL assembly group and the cruise assembly group are cooled by the same cooling circuit 62 .

[0106] The VTOL rotor 20 is primarily used for vertical takeoff and vertical landing. Meanwhile, the cruise rotor 22 is primarily used for cruising. Therefore, the maximum value of the sum of the first input power of the component group 24 corresponding to the VTOL rotor 20 and the second input power of the component group 24 corresponding to the cruise rotor 22 is not significantly different from the maximum values ​​of the first input power and the second input power. Therefore, even if the component group 24 corresponding to the VTOL rotor 20 and the component group 24 corresponding to the cruise rotor 22 share the battery 32, the battery 32 does not require a large capacity. Therefore, from the perspectives of circuit simplification and miniaturization of the battery 32, a combination of the component group 24 corresponding to the VTOL rotor 20, the component group 24 corresponding to the cruise rotor 22, and the battery 32 is suitable.

[0107] The input electrical power of the assembly group 24 is equivalent to the heat generated by the assembly group 24. Therefore, even if the assembly group 24 corresponding to the VTOL rotor 20 and the assembly group 24 corresponding to the cruise rotor 22 share the cooling circuit 62, the cooling circuit 62 does not require a large cooling capacity. Therefore, from the perspective of simplifying and miniaturizing the cooling circuit 62, the combination of the assembly group 24 corresponding to the VTOL rotor 20, the assembly group 24 corresponding to the cruise rotor 22, and the battery 32 is suitable.

[0108] In the embodiment of the present invention, it is also possible to

[0109] The rotor has two VTOL rotors 20 , which generate lift and offset each other's reaction forces when the aircraft 10 moves in a vertical direction.

[0110] The assembly group 24 includes two VTOL assembly groups (for example, assembly groups 24Ra and 24Ld) corresponding to the two VTOL rotors 20.

[0111] Both VTOL assembly groups are cooled by the same cooling circuit 62 .

[0112] If one of the two VTOL rotors 20 that cancel each other's reaction forces stops due to a malfunction or other reason, the other VTOL rotor 20 must also stop. In other words, the two VTOL rotors 20 that cancel each other's reaction forces always operate together. Therefore, from the perspective of efficiently cooling the electrical components, a combination of two component groups 24 and batteries 32 corresponding to the two VTOL rotors 20 that cancel each other's reaction forces is appropriate.

[0113] In the embodiment of the present invention, it is also possible to

[0114] The rotors include: two first VTOL rotors (e.g., VTOL rotors 20Ra and VTOL rotors 20Ld) and two second VTOL rotors (e.g., VTOL rotors 20La and VTOL rotors 20Rd); and a first cruise rotor (e.g., cruise rotor 22R) and a second cruise rotor (e.g., cruise rotor 22L), wherein the two first VTOL rotors and the two second VTOL rotors generate lift and cancel each other's reaction forces when the aircraft 10 moves in a vertical direction; and the first cruise rotor and the second cruise rotor generate thrust when the aircraft 10 moves in a horizontal direction.

[0115] The assembly group includes: two first VTOL assembly groups (e.g., assembly groups 24Ra and 24Ld) corresponding to the two first VTOL rotors; two second VTOL assembly groups (e.g., assembly groups 24La and 24Rd) corresponding to the two second VTOL rotors; a first cruise assembly group (e.g., assembly group 24R1) corresponding to the first cruise rotor; and a second cruise assembly group (e.g., assembly group 24L1) corresponding to the second cruise rotor.

[0116] The cooling circuit 62 includes a first cooling circuit and a second cooling circuit.

[0117] The two first VTOL assembly groups and the first cruise assembly group are cooled by the first cooling circuit, and the two second VTOL assembly groups and the second cruise assembly group are cooled by the second cooling circuit.

[0118] As described above, from the perspective of simplification and miniaturization of the cooling circuit 62, the combination of the component group 24 corresponding to the VTOL rotor 20, the component group 24 corresponding to the cruise rotor 22, and the battery 32 is suitable. Furthermore, from the perspective of efficiently cooling the electrical components, the combination of two component groups 24 corresponding to the two VTOL rotors 20 that cancel each other's reaction forces and the battery 32 is suitable.

[0119] In the embodiment of the present invention, it is also possible to

[0120] The first difference (D1) is smaller than the second difference (D2), wherein the first difference (D1) refers to the difference between the length from one of the first VTOL rotors (e.g., VTOL rotor 20Ra) to the first cruise rotor (e.g., cruise rotor 22R) and the length from another of the first VTOL rotors (e.g., VTOL rotor 20Ld) to the first cruise rotor (e.g., cruise rotor 22R); and the second difference (D2) refers to the difference between the length from one of the first VTOL rotors (e.g., VTOL rotor 20Ra) to the second cruise rotor (e.g., cruise rotor 22L) and the length from another of the first VTOL rotors (e.g., VTOL rotor 20Ld) to the second cruise rotor (e.g., cruise rotor 22L).

[0121] The above structure minimizes variations in the distance between two module groups 24 within the same group. Consequently, variations in the lengths of the parallel pipes 70a, 70b, and 70c within the same group are minimized. Consequently, by appropriately arranging the radiator 66, the differences in the lifts of the first through third pumps 68a, 68c can be minimized.

[0122] In the embodiment of the present invention, it is also possible to

[0123] Each of the component groups 24 includes a drive circuit (inverter 28 ) for an electric motor 26 .

[0124] In the embodiment of the present invention, it is also possible to

[0125] At least one of the component groups 24 has a battery 32 , which supplies electrical power to the electric motor 26 via the drive circuit.

[0126] In the embodiment of the present invention, it is also possible to

[0127] The cooling circuit 62 includes a pipe 64, a radiator 66, and a plurality of pumps (a first pump 68a to a third pump 68c).

[0128] The piping 64 includes: a plurality of parallel piping 70a, 70b, 70c; and a common piping 72, wherein the plurality of parallel piping 70a, 70b, 70c are connected in parallel with each other; the common piping 72 communicates the upstream side and the downstream side of each of the parallel piping 70a, 70b, 70c.

[0129] The parallel pipes 70a, 70b, and 70c are provided in the same number as the component groups 24 and are configured to cool the component groups 24.

[0130] The pump is installed in each of the parallel pipes 70a, 70b, and 70c.

[0131] The radiator 66 is provided on the common pipe 72.

[0132] The discharge head of the pump is determined by the length of the circulation passage formed by the parallel pipes 70 a , 70 b , 70 c and the common pipe 72 .

[0133] In the embodiment of the present invention, it is also possible to

[0134] The aircraft 10 has wings (a front wing 14 and a rear wing 16 ) that generate lift when moving forward.

Claims

1. A cooling system comprising a component group and a cooling circuit, wherein: The component group is composed of a plurality of electrical components that rotate a rotor, the rotor generating at least one of lift and thrust for the aircraft; The cooling circuit cools the plurality of electrical components. It is characterized in that The cooling system has a plurality of component groups corresponding to a plurality of the rotors. The rotors are VTOL rotors and cruise rotors, wherein the VTOL rotors generate lift when the aircraft moves in a vertical direction; and the cruise rotors generate thrust when the aircraft moves in a horizontal direction. The component groups are a VTOL component group corresponding to the VTOL rotor and a cruise component group corresponding to the cruise rotor, The VTOL assembly group and the cruise assembly group are cooled by the same cooling circuit.

2. A cooling system comprising a component group and a cooling circuit, wherein: The component group is composed of a plurality of electrical components that rotate a rotor, the rotor generating at least one of lift and thrust for the aircraft; The cooling circuit cools the plurality of electrical components. It is characterized in that The cooling system has a plurality of component groups corresponding to a plurality of the rotors. The rotors are: two first VTOL rotors and two second VTOL rotors; and a first cruise rotor and a second cruise rotor, wherein the two first VTOL rotors and the two second VTOL rotors generate lift and offset each other's reaction forces when the aircraft moves in a vertical direction; and the first cruise rotor and the second cruise rotor generate thrust when the aircraft moves in a horizontal direction. The assembly groups include: two first VTOL assembly groups corresponding to the two first VTOL rotors; two second VTOL assembly groups corresponding to the two second VTOL rotors; a first cruise assembly group corresponding to the first cruise rotor; and a second cruise assembly group corresponding to the second cruise rotor. The cooling circuits are a first cooling circuit and a second cooling circuit, The two first VTOL assembly groups and the first cruise assembly group are cooled by the first cooling circuit, and the two second VTOL assembly groups and the second cruise assembly group are cooled by the second cooling circuit.

3. The cooling system according to claim 2, characterized in that The first difference is smaller than the second difference, wherein the first difference refers to the difference between the length from one of the first VTOL rotors to the first cruise rotor and the length from another of the first VTOL rotors to the first cruise rotor; and the second difference refers to the difference between the length from one of the first VTOL rotors to the second cruise rotor and the length from another of the first VTOL rotors to the second cruise rotor.

4. The cooling system according to any one of claims 1 to 3, characterized in that: Each of the component groups includes a drive circuit for the electric motor.

5. The cooling system according to claim 4, characterized in that At least one of the component groups has a battery that supplies electric power to the electric motor via the drive circuit.

6. The cooling system according to any one of claims 1 to 3, characterized in that: The cooling circuit includes pipes, a radiator, and multiple pumps. The piping includes: a plurality of parallel pipings; and a common piping, wherein the plurality of parallel pipings are connected in parallel with each other; the common piping communicates the upstream side and the downstream side of each of the parallel pipings, The parallel pipes are provided in such a manner that the number thereof is equal to the number of the component groups and are configured to cool the component groups. The pump is provided in each of the parallel pipes. The radiator is provided on the common pipe. The discharge head of the pump is determined by the length of the circulation passage formed by the parallel pipe and the common pipe.

7. The cooling system according to any one of claims 1 to 3, characterized in that: The aircraft has wings that generate lift when the aircraft moves forward.

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