Drive systems and electrical systems

Abstract

In a drive system having a first drive unit and a second drive unit, the first drive unit and the second drive unit are to be cooled efficiently. [Solution] The first drive unit 31, the fan 33, and the second drive unit 32 are arranged in a line along the first direction X. The first drive unit 31 has a first cooling passage P1 that communicates with a first inlet P1A and a first outlet P1B on the fan 33 side and extends along the first direction X. The second drive unit 32 has a second cooling passage P2 that communicates with a second inlet P2A and a second outlet P2B on the fan 33 side and extends along the first direction X. The fan 33 circulates the refrigerant in the first cooling passage P1 by drawing in the refrigerant flowing out from the first outlet P1A and blowing it out in a direction intersecting the first direction X, and also circulates the refrigerant in the second cooling passage P2 by drawing in the refrigerant in a direction intersecting the first direction X and blowing it out to the second inlet P2A.

Description

Technical Field

[0001] The present invention relates to a drive system including a first drive unit, a second drive unit, and a fan.

Background Art

[0002] In recent years, efforts to achieve a low-carbon society or a decarbonized society have been active, and research and development on electrification technologies have been conducted in vehicles, aircraft, etc. in order to reduce CO2 emissions and improve energy efficiency.

[0003] There is a technology for cooling two units with the wind generated by a fan. In this technology, when the wind heated by cooling one unit flows into the other unit, there is a possibility that the other unit may not be sufficiently cooled. Therefore, there is a technology for cooling two units while preventing the wind heated by cooling one unit from flowing into the other unit.

[0004] For example, FIG. 30 of Patent Document 1 describes a propulsion device having a motor that rotates a propeller for propelling an aircraft, an inverter that supplies power to the motor, and an intermediate fan disposed between the motor and the inverter. Each of the motor and the inverter is one unit. The propeller, motor, intermediate fan, and inverter are arranged in a line along the rotational axis direction of the motor.

[0005] In the propulsion system described in Figure 30 of Patent Document 1, cooling passages extending in the direction of the motor's rotation axis are provided inside the motor casing (motor casing) and inside the inverter casing (inverter casing). An intermediate fan positioned between the motor and the inverter blows air flowing out from the motor's cooling passage and air flowing out from the inverter's cooling passage radially outward from the motor's rotation axis. This generates an outward forward flow (a cooling airflow that flows along the propeller wind generated by the rotation of the propeller) flowing through the motor's cooling passage, and this outward forward flow cools the motor. In addition, an outward reverse flow (a cooling airflow that flows in the opposite direction to the propeller wind) flows through the inverter's cooling passage, and this outward reverse flow cools the inverter. Furthermore, the outward forward flow flowing out from the motor flows radially outward from the motor's rotation axis and does not flow into the inverter's cooling passage. Similarly, the outward reverse flow flowing out from the inverter flows radially outward from the motor's rotation axis and does not flow into the motor's cooling passage. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-4442 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Incidentally, efficient cooling is a challenge in electrification technology. In the propulsion system described in Patent Document 1, the direction of the propeller airflow generated by the rotation of the propeller is the same as the direction of the airflow flowing into the motor's cooling passage in the outward forward flow. On the other hand, the direction of the airflow flowing into the inverter's cooling passage in the outward reverse flow is opposite to the direction of the propeller airflow. As a result, the airflow velocity of the airflow flowing into the inverter's cooling passage is slowed down by the propeller airflow. Consequently, the amount of air flowing into the inverter's cooling passage (the flow rate of the first outward reverse flow) decreases, reducing the efficiency of cooling the inverter. As a result, there is a risk that the inverter may not be adequately cooled.

[0008] In view of the above background, the present invention aims to efficiently cool the first drive unit and the second drive unit in a drive system having a first drive unit and a second drive unit. This will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0009] To solve the above problems, one aspect of the present invention is a drive system (16) comprising a first drive unit (31), a second drive unit (32), and a fan (33), wherein the first drive unit, the fan, and the second drive unit are arranged in this order in a line along a first direction (X) from the first drive unit toward the second drive unit, and the first drive unit has a first inlet (P1A) formed on the opposite side of the fan and a first outlet (P1B) formed on the fan side, along the first direction The second drive unit has a first cooling passage (P1) extending in a certain direction, and the second drive unit has a second inlet (P2A) formed on the fan side and a second outlet (P2B) formed on the opposite side of the fan, and has a second cooling passage (P2) extending in the first direction, and the fan circulates the refrigerant (air) flowing out from the first outlet and blows it out in a direction intersecting the first direction, and also circulates the refrigerant in the second cooling passage by drawing in the refrigerant in a direction intersecting the first direction and blowing it out to the second inlet.

[0010] In this embodiment, the fan blows the refrigerant flowing out from the first outlet in a direction intersecting the first direction. This prevents the refrigerant flowing out from the first outlet from flowing into the second cooling passage from the second inlet. Therefore, it is possible to prevent the refrigerant flowing out from the first outlet, which has been heated in the first cooling passage, from flowing into the second cooling passage from the second outlet, thereby reducing the cooling efficiency of the second drive unit. In addition, the refrigerant flowing out from the second outlet flows away from the first inlet. This prevents the refrigerant flowing out from the second outlet, which has been heated in the second cooling passage, from flowing into the first cooling passage from the first inlet, thereby reducing the cooling efficiency of the first drive unit. Therefore, in a drive system having a first drive unit and a second drive unit, the first drive unit and the second drive unit can be cooled efficiently.

[0011] In the above embodiment, the fan may have a hub (61) formed integrally with one another, a plurality of first blades (62) that draw in the refrigerant from the first outlet and blow it out in a direction intersecting the first direction, and a plurality of second blades (63) that draw in the refrigerant in a direction intersecting the first direction and blow it out to the second inlet.

[0012] In this embodiment, the fan can circulate the refrigerant through the first and second cooling passages simply by rotating the hub around a first direction. This makes it easier to cool the first and second drive units with the refrigerant.

[0013] In the above embodiment, it is preferable to have an isolation wall (71) which has one end positioned to cover the outer circumference of the boundary between the first blade and the second blade, extends radially outward from the one end of the hub, and separates the refrigerant blown out by the first blade in a direction intersecting the first direction from the refrigerant sucked in by the second blade in a direction intersecting the first direction.

[0014] In this embodiment, the isolation wall separates the refrigerant flowing out from the first outlet, which is blown out by the first blade, from the refrigerant flowing into the second inlet, which is drawn in by the second blade. This makes it possible to more reliably suppress the decrease in the cooling efficiency of the second drive unit caused by the refrigerant flowing out from the first outlet, which has been heated in the first cooling passage, flowing into the second cooling passage from the second inlet.

[0015] In the above embodiment, the drive system may have an isolation duct (72) formed integrally with the isolation wall, extending from the radially outer end of the isolation wall along the first direction and covering the outer circumference of the second drive unit.

[0016] In this embodiment, the isolation duct separates the refrigerant flowing out from the first outlet, which is blown out by the first blade, from the refrigerant flowing into the second inlet, which is sucked in by the second blade. This makes it possible to more reliably suppress the decrease in the cooling efficiency of the second drive unit caused by the refrigerant flowing out from the first outlet, which has been heated in the first cooling passage, flowing into the second cooling passage from the second inlet.

[0017] In the above embodiment, the isolation wall may be formed integrally with the hub.

[0018] In this embodiment, since the isolation wall is formed integrally with the hub, it becomes easier to install the isolation wall.

[0019] In the above embodiment, the second drive unit has a duct (42) defining the second cooling passage, one end of the isolation wall is spaced apart from and close to the outer circumference of the boundary between the first blade and the second blade, and the isolation duct is preferably attached to the duct.

[0020] In this embodiment, since the isolation wall and the hub are separate components, the isolation wall does not rotate around the first direction even when the hub rotates. As a result, the drive system does not consume power to rotate the isolation wall. Therefore, the power consumption of the drive system can be reduced compared to when the isolation wall and the hub are integrally formed.

[0021] In the above embodiment, the first drive unit and the second drive unit each have a shaft (35) extending along the first direction, which is rotatably supported around the first direction and coupled to the hub, and a propeller (36) fixed to the shaft, wherein the first drive unit and the second drive unit rotate the shaft around the first direction to generate propulsive air flowing along the first direction from the propeller, the hub rotates together with the shaft around the first direction, and the propeller is preferably positioned at the first end of the shaft on the second drive unit side.

[0022] In this configuration, the rotation of the propeller generates a propulsive airflow that flows along the first direction. As a result, a portion of the propulsive airflow easily flows from the first inlet into the first cooling passage. The refrigerant that has flowed through the second cooling passage flows out of the second outlet along the propulsive airflow along the first direction. As a result, the refrigerant that has flowed through the second cooling passage easily flows out from the second outlet. This suppresses a decrease in the flow rate of the refrigerant flowing through the first cooling passage due to the propulsive airflow, and also suppresses a decrease in the flow rate of the refrigerant flowing through the second cooling passage due to the propulsive airflow. Therefore, the drive system can efficiently cool both the first drive unit and the second drive unit.

[0023] In the above aspect, the first drive unit and the second drive unit are rotatably supported about the first direction and coupled to the hub, and include a shaft (35) extending along the first direction, and a propeller (36) fixed to the shaft. The first drive unit and the second drive unit rotate the shaft about the first direction to generate propelling wind flowing along the first direction from the propeller. The hub rotates about the first direction together with the shaft, and the propeller may be disposed at a second end of the shaft on the first drive unit side.

[0024] According to this aspect, propelling wind flowing along the first direction is generated by the rotation of the propeller. Therefore, a part of the propelling wind easily flows into the first cooling passage from the first inlet. Further, the refrigerant flowing through the second cooling passage flows along the first direction together with the propelling wind from the second outlet. Therefore, the refrigerant flowing through the second cooling passage easily flows out from the second outlet. Thereby, it is suppressed that the flow rate of the refrigerant flowing through the first cooling passage decreases due to the propelling wind, and it is suppressed that the flow rate of the refrigerant flowing through the second cooling passage P2 decreases due to the propelling wind. Therefore, the drive system can efficiently cool the first drive unit and the second drive unit.

[0025] In order to solve the above problems, an aspect of the present invention is an electrical system (16) including a first electrical device (31), a second electrical device (32), and a fan (33). The first electrical device, the fan, and the second electrical device are arranged in a row along a first direction (X) from the first electrical device toward the second electrical device in this order. The first electrical device has a first inlet (P1A) formed on the side opposite to the fan and a first outlet (P1B) formed on the fan side, and has a first cooling passage (P1) extending along the first direction. The second electrical device has a second inlet (P2A) formed on the fan side and a second outlet (P2B) formed on the side opposite to the fan, and has a second cooling passage (P2) extending along the first direction. The fan sucks in the refrigerant (air) flowing out from the first outlet and blows it out in a direction intersecting the first direction, thereby circulating the refrigerant through the first cooling passage, and sucks in the refrigerant in a direction intersecting the first direction and blows it out to the second inlet, thereby circulating the refrigerant through the second cooling passage.

[0026] According to this aspect, since the fan blows out the refrigerant flowing out from the first outlet in a direction intersecting the first direction, it is possible to suppress the refrigerant flowing out from the first outlet from flowing into the second cooling passage from the second outlet. Therefore, it is possible to suppress the refrigerant flowing out from the first outlet heated in the first cooling passage from flowing into the second cooling passage from the second outlet and reducing the cooling efficiency of the second electrical device. Further, the refrigerant flowing out from the second outlet flows in a direction away from the first inlet. Thereby, it is possible to suppress the refrigerant flowing out from the second outlet heated in the second cooling passage from flowing into the first cooling passage from the first outlet and reducing the cooling efficiency of the first drive unit. Therefore, in an electrical system having the first electrical device and the second electrical device, the first electrical device and the second electrical device can be efficiently cooled.

Effect of the Invention

[0027] According to the above embodiment, in a drive system having a first drive unit and a second drive unit, the first drive unit and the second drive unit can be efficiently cooled. [Brief explanation of the drawing]

[0028] [Figure 1] Perspective view showing an aircraft according to the first embodiment. [Figure 2] schematic cross-section of the propulsion unit [Figure 3] Perspective view of the drive system [Figure 4] Cross-sectional view of the outer periphery of the first drive unit, fan, and second drive unit. [Figure 5] Cross-sectional view of the main parts of the second drive unit and isolation plate. [Figure 6] schematic cross-section of the drive system [Figure 7] Perspective view of the drive system according to the second embodiment [Figure 8] Cross-sectional view of the outer periphery of the first drive unit, fan, and second drive unit. [Figure 9] schematic cross-section of the drive system [Figure 10] Schematic cross-sectional view of the drive system relating to the first modified example. [Figure 11] Schematic cross-sectional view of the drive system relating to the second modified example. [Modes for carrying out the invention]

[0029] <<First Embodiment>> <Aircraft 1> Hereinafter, an aircraft 1 according to a first embodiment of the present invention will be described with reference to the drawings. In the drawings and the following description, front, back, left, right, up, and down are directions defined with respect to the aircraft 1.

[0030] Figure 1 is a perspective view showing an aircraft 1 according to the first embodiment. The aircraft 1 is an electric vertical take-off and landing (eVTOL) aircraft capable of taking off and landing vertically. The aircraft 1 has a fuselage 2 extending in the longitudinal direction, a forewing 3 extending in the lateral direction and connected to the front of the fuselage 2, a rearwing 4 extending in the lateral direction and connected to the rear of the fuselage 2, a left arm 5L extending in the longitudinal direction and connecting the left end of the forewing 3 and the left side of the rearwing 4, and a right arm 5R extending in the longitudinal direction and connecting the right end of the forewing 3 and the right side of the rearwing 4.

[0031] The front of the fuselage 2 is provided with a cabin (not shown) for the crew. The rear end of the fuselage 2 is provided with left and right propulsion units 7 (details described later) for generating forward thrust for the aircraft 1.

[0032] The left arm 5L and the right arm 5R are each provided with a plurality (for example, four) of lifting units 10 spaced apart in the front-rear direction to generate upward and downward forces for the aircraft 1. Each lifting unit 10 has a lifting drive device 12 and a lifting propeller 13 attached to the lifting drive device 12. The lifting drive device 12 has an electric motor (not shown) and is configured to rotate the lifting propeller 13 by the driving force of this electric motor.

[0033] <Propulsion Unit 7> Figure 2 is a schematic cross-sectional view of a propulsion unit 7. Each propulsion unit 7 has a support 15 and a drive system 16 supported by the support 15.

[0034] The support 15 is fixed to the rear end of the body 2 (see Figure 1). The support 15 has a cylindrical nacelle 20 extending in the front-rear direction and front and rear mounting frames 21 fixed to the inner circumferential surface of the nacelle 20. Each mounting frame 21 has an annular hub 23 provided concentrically with the nacelle 20 and a plurality of spokes 24 extending radially from the outer circumferential surface of the hub 23 and connected to the inner circumferential surface of the nacelle 20.

[0035] <Drive System 16> As shown in Figure 2, the drive system 16 comprises a first drive unit 31, a second drive unit 32, a fan 33, an isolation plate 34, a shaft 35 extending in the front-rear direction and rotatably supported by the drive system 16, and a propeller 36 fixed to the rear of the shaft 35. The drive system 16 is housed in the nacelle 20. The drive system 16 is fixed to the hubs 23 of the front and rear mounting frames 21.

[0036] The direction from the first drive unit 31 to the second drive unit 32 is denoted as the first direction X. The first drive unit 31, the fan 33, and the second drive unit 32 are arranged in a line along the first direction X in this order. The first drive unit 31 is fixed to the hub 23 of the front mount frame 21. The second drive unit 32 is fixed to the hub 23 of the rear mount frame 21. The drive system 16 is an example of an electrical system. The first drive unit 31 is an example of a first electrical device. The second drive unit 32 is an example of a second electrical device. The first and second electrical devices are devices that consume electricity. The electrical system is a system comprising the first electrical device, the second electrical device, and the fan.

[0037] The shaft 35 extends along a first direction X. A conical rear cover 37, which expands in diameter toward the front, is fixed to the first end 35A (rear end) of the shaft 35 on the second drive unit 32 side. The rear cover 37 is located behind the center of the propeller 36. A conical front cover 38, which expands in diameter toward the rear, is fixed to the second end 35B (front end) of the shaft 35 on the first drive unit 31 side.

[0038] The propeller 36 is configured to rotate integrally with the shaft 35 as the shaft 35 rotates, thereby generating a propulsive airflow along the first direction X. The propeller 36 generates a forward thrust for the aircraft 1 by generating this propulsive airflow.

[0039] Each of the first drive unit 31 and the second drive unit 32 includes an electric motor 41 and a duct 42 that covers the outer circumference of the electric motor 41. The electric motor 41 incorporates a control device 43 that controls the driving of the electric motor 41. The control device 43 includes an inverter (not shown). The inverter becomes relatively hot. The electric motor 41 supports a shaft 35 so as to be rotatable around its axis and rotates the shaft 35. The first drive unit 31 and the second drive unit 32 are units that include an electric motor 41 that rotates the shaft 35. Note that the first drive unit 31 and the second drive unit 32 may be any units relating to an electric motor.

[0040] Figure 3 is a perspective view of the drive system 16. In Figure 3, the propeller 36 and other components are omitted from the illustration. In the first drive unit 31 and the second drive unit 32, the electric motor 41 is formed in a cylindrical shape extending in the front-rear direction on the outer circumference of the shaft 35, and the duct 42 is formed in a cylindrical shape covering the outer circumference of the electric motor 41.

[0041] The electric motor 41 is an inner rotor type three-phase AC motor. The electric motor 41 has a housing 51 that houses the rotor, stator, and control device 43, and a pair of front and rear covers 52 attached to the front and rear of the housing 51.

[0042] The housing 51 is formed in a cylindrical shape extending in the front-rear direction on the outer circumference of the shaft 35. The stator is fixed inside the housing 51 and is also formed in a cylindrical shape. The rotor is located inside the stator, facing the stator at a distance, and is integrally formed with the shaft 35. The stator has a plurality of coils (not shown), and the rotor has a plurality of permanent magnets (not shown) fixed to its outer circumference. The magnetic force of the coils of the stator and the magnetic force of the permanent magnets of the rotor cause the rotor to rotate together with the shaft 35.

[0043] The outer circumferential surface 51A of the housing 51 is provided with a plurality of fastening protrusions 53 that project radially outward at intervals in the circumferential direction of the housing 51, and a plurality of cooling fins 54 provided between adjacent fastening protrusions 53. Each fastening protrusion 53 and each cooling fin 54 is formed integrally with the housing 51.

[0044] Each fastening projection 53 extends continuously along the first direction X from the front end to the rear end of the housing 51 and is formed in the shape of a rod with a rectangular cross-section. Each cooling fin 54 also extends continuously along the first direction X from the front end to the rear end of the housing 51 and is formed in the shape of a plate that protrudes upward. That is, each fastening projection 53 and each cooling fin 54 extends parallel to each other along the first direction X. Each fastening projection 53 protrudes radially outward from the housing 51 than each cooling fin 54. A duct 42 is attached to the radially outward end of each fastening projection 53. Furthermore, as will be described later, a support member 55, which is coupled to an isolation plate 34, is attached together with the duct 42 to the front end of each fastening projection 53 of the second drive unit 32.

[0045] A cooling passage P is formed between the outer circumferential surface 51A of the housing 51 and the duct 42, extending continuously in the front-rear direction from the front end to the rear end of the housing 51.

[0046] A pair of front and rear covers 52 are positioned at the front and rear of the housing 51, closing the front and rear openings of the housing 51. The covers 52 are formed in a disc shape and have fastening portions 52A on their outer circumference that correspond to the front and rear end faces of each fastening projection 53. Each fastening portion 52A is fastened with a bolt to the end face (front end face or rear end face) of the corresponding fastening projection 53. The fastening portions 52A of the covers 52 and the fastening projections 53 may be joined using rivets, adhesive, welding, or a combination of these methods.

[0047] The fan 33 includes a hub 61 which includes a disc portion extending radially from the housing 51, a plurality of first blades 62 which protrude from the side (front side) of the first drive unit 31 of the hub 61, and a plurality of second blades 63 which protrude from the side (front side) of the second drive unit 32 of the hub 61. The hub 61, the plurality of first blades 62, and the plurality of second blades 63 are integrally formed with each other.

[0048] The hub 61 is connected to the shaft 35. As a result, the hub 61 rotates together with the shaft 35. As the hub 61 rotates, the multiple first blades 62 blow air radially outward (in a direction intersecting the first direction X), and the multiple second blades 63 draw air radially inward (in a direction intersecting the first direction X). The fan 33 is positioned between the first drive unit 31 and the second drive unit 32, and the fan 33 is not located at the front-rear end of the drive system 16. This prevents foreign objects (e.g., birds) moving from the front or rear of the drive system 16 toward the fan 33 from coming into contact with the fan 33 and damaging it.

[0049] The isolation plate 34 has an isolation wall 71 and an isolation duct 72 that are integrally formed with each other. The isolation wall 71 is formed in an annular shape that encircles the outer circumference of the hub 61. The isolation wall 71 has a radially inner end (one end) positioned to cover the outer circumference of the boundary between the first blade 62 and the second blade 63, and extends radially outward from the inner end of the hub 61. The isolation duct 72 is formed in a cylindrical shape that covers the outer circumference (duct 42) of the second drive unit 32.

[0050] Figure 4 is a cross-sectional view of the outer periphery of the first drive unit 31, the fan 33, and the second drive unit 32. The inner end of the isolation wall 71 is spaced apart from and close to the outer periphery of the boundary between the first blade 62 and the second blade 63. The isolation duct 72 is formed integrally with the isolation wall 71 and extends from the radially outer end of the isolation wall 71 along the first direction X. As shown in Figure 4, the isolation duct 72 is connected to a support member 55. The support member 55 is fixed together with the duct 42 to the front end of a fastening projection 53 with bolts (not shown). Thus, the isolation duct 72 is attached to the duct 42 via the support member 55. The connection between the isolation duct 72 and the support member 55 may be by rivet, by bolt and nut fastening, by adhesive, by welding, or a combination of these.

[0051] Figure 5 is a cross-sectional view of the main parts of the second drive unit 32 and the isolation duct 72. As shown in Figure 5, the isolation duct 72 is supported by support members 55 on each of the multiple fastening protrusions 53 that are spaced apart in the circumferential direction of the housing 51. This ensures that the radial distance between the isolation duct 72 and the housing 51 is maintained at a predetermined distance around the entire circumference.

[0052] Next, the cooling of the drive system 16 will be described. Figure 6 is a schematic cross-sectional view of the drive system 16. Figure 6 omits the illustration of the rear cover 37, etc. The cooling passage P of the first drive unit 31 is referred to as the "first cooling passage P1". The cooling passage P of the second drive unit 32 is referred to as the "second cooling passage P2".

[0053] The outer circumferential surface 51A of the housing 51 and the duct 42 of the first drive unit 31 define a first cooling passage P1. The first drive unit 31 has a first inlet P1A formed on the side opposite to the fan 33 (front side) and a first outlet P1B formed on the side opposite to the fan 33 (rear side), and has a first cooling passage P1 extending along the first direction X. The outer circumferential surface 51A of the housing 51 and the duct 42 of the second drive unit 32 define a second cooling passage P2. The second drive unit 32 has a second inlet P2A formed on the side opposite to the fan 33 (front side) and a second outlet P2B formed on the side opposite to the fan 33 (rear side), and has a second cooling passage P2 extending along the first direction X.

[0054] The first drive unit 31 and the second drive unit 32 rotate the shaft 35 around a first direction X. As the shaft 35 rotates, the fan 33 and the propeller 36 rotate. As the fan 33 rotates, multiple first blades 62 draw air in from the first outlet P1B and blow it out radially outward, and multiple second blades 63 draw air in radially inward and blow it out to the second inlet P2A. As the multiple first blades 62 draw air in from the first outlet P1B, the air flows through the first cooling passage P1, and the first drive unit 31 is cooled. Also, as the multiple second blades 63 blow air out to the second inlet P2A, the air flows through the second cooling passage P2, and the second drive unit 32 is cooled.

[0055] Air heated by flowing through the first cooling passage P1 (hereinafter referred to as "first exhaust e1") is blown radially outward by a plurality of first blades 62. The first exhaust e1 flows along the outer circumference of the isolation wall 71, and further flows along the outer circumference of the isolation duct 72. As the first exhaust e1 flows along the outer circumferences of the isolation wall 71 and the isolation duct 72, the first exhaust e1 is diffused.

[0056] Furthermore, when the shaft 35 rotates around the first direction X, a propulsion airflow is generated from the propeller 36 that flows along the first direction X. The direction of airflow into the first inlet P1A is the same as the direction of the propulsion airflow (first direction X). Therefore, as a portion of the propulsion air flows into the first inlet P1A, air easily flows into the first inlet P1A. Also, since the direction of airflow through the first cooling passage P1 is the same as the direction of the propulsion airflow (first direction X), the air that has flowed through the first cooling passage P1 is easily discharged from the first outlet P1B. Consequently, the amount of air flowing through the first cooling passage P1 increases with the propulsion airflow. The amount of air flowing through the first cooling passage P1 increases as the propulsion airflow becomes stronger. As a result, the first drive unit 31 is efficiently cooled.

[0057] The air drawn radially inward by the multiple second blades 63 (hereinafter referred to as "second intake air i2") flows into the second cooling passage P2 from the second inlet P2A. The second intake air i2 is the air that flows between the duct 42 and the isolation duct 72 of the second drive unit 32 and is drawn in by the multiple second blades 63. The air flowing between the duct 42 and the isolation duct 72 of the second drive unit 32 (second intake air i2) is isolated from the first exhaust air e1 by the isolation plate 34.

[0058] The direction of airflow through the second cooling passage P2 and the direction of airflow out of the second outlet P2B are the same as the direction of propulsion airflow (first direction X). Therefore, the air that has flowed through the second cooling passage P2 is easily discharged from the second outlet P2B. This makes it easier for the second intake air i2 to flow into the second cooling passage P2. As a result, a sufficient amount of air is ensured to flow through the second cooling passage P2. This allows the second drive unit 32 to be cooled efficiently. Thus, the second drive unit 32 is properly cooled.

[0059] Next, we will explain the effects of the drive system 16.

[0060] Fan 33 draws in air flowing out from the first outlet P1B and blows it radially outward, thereby circulating air in the first cooling passage P1. Fan 33 also draws in air radially inward and blows it out at the second inlet P2A, thereby circulating air in the second cooling passage P2. Fan 33 blows out air flowing out from the first outlet P1B radially outward. This prevents air flowing out from the first outlet P1B from flowing into the second cooling passage P2 from the second inlet P2A. Therefore, it is possible to prevent air heated in the first cooling passage P1 from flowing out from the first outlet P1B into the second cooling passage P2 from the second outlet P2B, thereby preventing a decrease in the cooling efficiency of the second drive unit 32. In addition, the air flowing out from the second outlet P2B flows away from the first inlet P1A. This prevents the refrigerant, which has been heated in the second cooling passage P2 and is flowing out from the second outlet P2B, from flowing into the first cooling passage P1 from the first inlet P1A, thereby suppressing a decrease in the cooling efficiency of the first drive unit 31. Consequently, the drive system 16 (electrical system) can efficiently cool the first drive unit 31 (first electrical device) and the second drive unit 32 (second electrical device).

[0061] The fan 33 has a hub 61 formed integrally with each other, a plurality of first blades 62, and a plurality of second blades 63. The fan 33 can circulate air into the first cooling passage P1 and the second cooling passage P2 simply by rotating the hub 61 around a first direction X. This makes it easy to cool the first drive unit 31 and the second drive unit 32 with air.

[0062] The isolation wall 71 separates the air flowing out from the first outlet P1B, which is blown out by the first blade 62, from the air flowing into the second inlet P2A, which is drawn in by the second blade 63. This makes it possible to more reliably suppress the decrease in the cooling efficiency of the second drive unit 32 caused by air flowing out from the first outlet P1B, which has been heated in the first cooling passage P1, flowing into the second cooling passage P2 from the second inlet P2A.

[0063] The isolation duct 72 separates the air flowing out from the first outlet P1B, which is blown out by the first blade 62, from the air flowing into the second inlet P2A, which is drawn in by the second blade 63. This makes it possible to more reliably suppress the decrease in the cooling efficiency of the second drive unit 32 caused by air flowing out from the first outlet P1B, which has been heated in the first cooling passage P1, flowing into the second cooling passage P2 from the second inlet P2A.

[0064] Since the isolation wall 71 and the hub 61 are separate components, even if the hub 61 (shaft 35) rotates, the isolation wall 71 does not rotate around the first direction X. As a result, the drive system 16 does not consume power to rotate the isolation wall 71. Therefore, the power consumption of the drive system 16 can be reduced compared to when the isolation wall 71 and the hub 61 are formed as a single unit.

[0065] The propeller 36 is positioned at the first end 35A of the shaft 35 on the side of the first drive unit 31. The rotation of the propeller 36 generates a propulsive airflow that flows along the first direction X. As a result, a portion of the propulsive airflow easily flows from the first inlet P1A into the first cooling passage P1. The air that has flowed through the second cooling passage P2 flows along the first direction X together with the propulsive airflow from the second outlet P2B. As a result, the air that has flowed through the second cooling passage P2 easily flows out from the second outlet P2B. This suppresses a decrease in the airflow rate of the air flowing through the first cooling passage P1 due to the propulsive airflow, and also suppresses a decrease in the airflow rate of the air flowing through the second cooling passage P2 due to the propulsive airflow. Therefore, the drive system 16 can efficiently cool the first drive unit 31 and the second drive unit 32.

[0066] <<Second Embodiment>> Figure 7 is a perspective view of the drive system 16 according to the second embodiment. As shown in Figure 7, the differences between the drive system 16 of the second embodiment and the drive system 16 of the first embodiment are the following three points: 1. The isolation wall 71 and the hub 61 are integrally formed. 2. The propeller 36 is located at the second end 35B of the shaft 35 on the second drive unit 32 side (see Figure 9). 3. The first direction X is directed downward. In the following description of the second embodiment, the same or similar components as in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0067] Figure 8 is a cross-sectional view of the main part of the drive system 16. As shown in Figure 8, the isolation plate 34 has an isolation wall 71 and an isolation duct 72 that are integrally formed with each other. The inner end of the isolation wall 71 is integrated with the boundary between the first blade 62 and the second blade 63. Consequently, the drive system 16 of this embodiment does not have a support member 55. The isolation plate 34 is supported by the hub 61. Since the isolation wall 71 is integrally formed with the hub 61, it becomes easy to install the isolation wall 71. Also, the number of parts can be reduced. And consequently, it becomes easy to install the isolation plate 34.

[0068] Figure 9 is a schematic cross-sectional view of the drive system 16. The rear cover 37 and front cover 38 are omitted from the illustration in Figure 9. As shown in Figure 9, in the drive system 16 of this embodiment, the propeller 36 generates a propulsive airflow, thereby generating upward thrust for the aircraft 1.

[0069] As shown in Figure 9, the propeller 36 is positioned at the second end 35B of the shaft 35 on the first drive unit 31 side. The rotation of the propeller 36 generates a propulsive airflow that flows along the first direction X. As a result, a portion of the propulsive airflow easily flows from the first inlet P1A into the first cooling passage P1. The air that has flowed through the second cooling passage P2 flows along the first direction X together with the propulsive airflow from the second outlet P2B. As a result, the air that has flowed through the second cooling passage P2 easily flows out from the second outlet P2B. This suppresses a decrease in the airflow rate of the air flowing through the first cooling passage P1 due to the propulsive airflow, and also suppresses a decrease in the airflow rate of the air flowing through the second cooling passage P2 due to the propulsive airflow. Therefore, the drive system 16 can efficiently cool the first drive unit 31 and the second drive unit 32.

[0070] <<First variation>> Figure 10 is a schematic cross-sectional view of the drive system 16 according to the first modified example. As shown in Figure 10, the drive system 16 of the first modified example is a drive system 16 in which the isolation wall 71 (isolation plate 34) and the hub 61 are integrated into one unit, compared to the drive system 16 of the first embodiment. In other words, the drive system 16 of the first modified example is a drive system 16 in which the isolation plate 34, the hub 61, and the support member 55 for attaching the isolation duct 72 to the duct 42 are replaced with the integrally formed isolation wall 71 (isolation plate 34) and hub 61 of the second embodiment, compared to the drive system 16 of the first embodiment. Similar to the drive system 16 of the first embodiment, in the drive system 16 of the first modified example, the direction of the propulsion airflow (first direction X) is directed towards the rear.

[0071] <<Second variation>> Figure 11 is a schematic cross-sectional view of the drive system 16 according to the second modified example. As shown in Figure 11, the drive system 16 of the second modified example is a drive system 16 in which the isolation wall 71 (isolation plate 34) and the hub 61 are separate components from the drive system 16 of the second embodiment. That is, the drive system 16 of the second modified example is a drive system 16 in which the integrally formed isolation wall 71 (isolation plate 34) and hub 61 of the drive system 16 of the second embodiment are replaced with the isolation plate 34 of the first embodiment, the hub 61, and the support member 55 that attaches the isolation duct 72 to the duct 42. Similar to the drive system 16 of the second embodiment, in the drive system 16 of the second modified example, the direction of the propulsion airflow (first direction X) is downward.

[0072] This concludes the description of the embodiments, but the present invention is not limited to the above embodiments and can be broadly modified and implemented. For example, in the drive system 16 of the first embodiment and the drive system 16 of the second embodiment, the drive system 16 may be supported in such a way that the direction of the propulsion airflow can be changed. The drive system 16 does not have to include a shaft 35 and a propeller 36. In the first and second embodiments, air was used as a refrigerant, but the refrigerant may be a fluid. The refrigerant may be a gas or a liquid.

[0073] The drive system 16 of the first and second embodiments may not be provided with an isolation plate 34. The fan 33 may be equipped with a drive device, and the hub 61 may be configured to rotate by the drive device. Also, in the drive system 16 of the first and second embodiments, the isolation duct 72 may be omitted from the isolation plate 34. That is, the drive system 16 may have only an isolation wall 71 instead of an isolation plate 34. Furthermore, the electric motor 41 does not have to be an inner rotor type three-phase AC motor. [Explanation of Symbols]

[0074] 16: Drive system (electrical system) 31: First drive unit (first electrical device) 32: Second drive unit (second electrical device) 33: Fan 35: Shaft 35A: 1st end 35B: 2nd end 36: Propeller 42: Duct 61: Hub 62: First Blade 63: Second Blade 71 :Isolation wall 72: Isolation duct P: Cooling passage P1: 1st cooling passage P1A: 1st inlet P1B: 1st outlet P2: 2nd cooling passage P2A: 2nd inlet P2B: 2nd outlet X: 1st direction

Claims

1. A drive system comprising a first drive unit, a second drive unit, and a fan, The first drive unit, the fan, and the second drive unit are arranged in this order in a line along the first direction from the first drive unit to the second drive unit. The first drive unit has a first inlet formed on the side opposite to the fan and a first outlet formed on the fan side, and has a first cooling passage extending along the first direction. The second drive unit has a second inlet formed on the fan side and a second outlet formed on the opposite side of the fan, and has a second cooling passage extending along the first direction. The aforementioned fan is a drive system that circulates the refrigerant in the first cooling passage by drawing in the refrigerant flowing out from the first outlet and blowing it out in a direction intersecting the first direction, and also circulates the refrigerant in the second cooling passage by drawing in the refrigerant in a direction intersecting the first direction and blowing it out to the second inlet.

2. The drive system according to claim 1, wherein the fan comprises a hub formed integrally with one another, a plurality of first blades that draw in the refrigerant from the first outlet and blow it out in a direction intersecting the first direction, and a plurality of second blades that draw in the refrigerant in a direction intersecting the first direction and blow it out to the second inlet.

3. The drive system according to claim 2, further comprising an isolation wall having one end positioned to cover the outer circumference of the boundary between the first blade and the second blade, extending radially outward from the one end of the hub, and separating the refrigerant blown out by the first blade in a direction intersecting the first direction from the refrigerant sucked in by the second blade in a direction intersecting the first direction.

4. The drive system according to claim 3, further comprising an isolation duct formed integrally with the isolation wall, extending from the radially outer end of the isolation wall along the first direction, and covering the outer circumference of the second drive unit.

5. The drive system according to claim 3 or 4, wherein the isolation wall is formed integrally with the hub.

6. The second drive unit has a duct that defines the second cooling passage, The one end of the isolation wall is spaced apart from and close to the outer circumference of the boundary between the first blade and the second blade. The drive system according to claim 4, wherein the isolation duct is attached to the duct.

7. The first drive unit and the second drive unit are supported by a shaft extending along the first direction, which is rotatably supported around the first direction and coupled to the hub, It has a propeller fixed to the shaft, The first drive unit and the second drive unit rotate the shaft around the first direction to generate propulsion air flowing along the first direction from the propeller. The hub rotates together with the shaft around the first direction, The drive system according to claim 3 or 4, wherein the propeller is located at the first end of the shaft on the second drive unit side.

8. The first drive unit and the second drive unit are supported by a shaft extending along the first direction, which is rotatably supported around the first direction and coupled to the hub, It has a propeller fixed to the shaft, The first drive unit and the second drive unit rotate the shaft around the first direction to generate propulsion air flowing along the first direction from the propeller. The hub rotates together with the shaft around the first direction, The drive system according to claim 3 or 4, wherein the propeller is located at the second end of the shaft on the first drive unit side.

9. An electrical system comprising a first electrical device, a second electrical device, and a fan, The first electrical device, the fan, and the second electrical device are arranged in this order in a line along the first direction from the first electrical device to the second electrical device. The first electrical device has a first inlet formed on the opposite side of the fan and a first outlet formed on the fan side, and has a first cooling passage extending along the first direction. The second electrical device has a second inlet formed on the fan side and a second outlet formed on the opposite side of the fan, and has a second cooling passage extending along the first direction. The aforementioned fan is an electrical system that circulates the refrigerant in the first cooling passage by drawing in the refrigerant flowing out from the first outlet and blowing it out in a direction intersecting the first direction, and also circulates the refrigerant in the second cooling passage by drawing in the refrigerant in a direction intersecting the first direction and blowing it out to the second inlet.

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