Drive systems and electrical systems

Abstract

To efficiently cool two cylindrical drive units or electrical devices in a system in which two cylindrical drive units or electrical devices are arranged coaxially with each other. [Solution] The first drive unit 31 (electrical device) has a first inlet 62A and a first outlet 63A formed on the opposite side from the second drive unit 32 (electrical device), and includes a first cooling passage 61A that extends spirally around the rotation axis 34 on the outer circumference of the first drive unit 31, and a first heat dissipation fin 51A that protrudes into the interior of the first cooling passage 61A. The second drive unit 32 has a second inlet 62B and a second outlet 63B formed on the side of the first drive unit 31, and includes a second cooling passage 61B that extends spirally around the rotation axis 34 on the outer circumference of the second drive unit 32, and a second heat dissipation fin 51B that protrudes into the interior of the second cooling passage 61B.

Description

Technical Field

[0001] The present invention relates to a drive system for driving a rotating shaft and an electric system, comprising a cylindrical first drive unit and a second drive unit arranged coaxially with each other.

Background Art

[0002] In recent years, efforts towards realizing 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] Regarding this, there is a technology for cooling a drive system that drives a rotating shaft. For example, FIG. 9 of Patent Document 1 describes a drive device having a motor, an inverter device, and a blower fan fixed to the rotating shaft of the motor. The drive device is a drive system that rotates the rotating shaft. In the drive device, as the blower fan rotates, cooling air flows axially along the outer peripheral surfaces of the motor and the inverter device. Thereby, the motor and the inverter are cooled. With respect to the cooling air, the motor is arranged on the upstream side and the inverter device is arranged on the downstream side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in the drive device described in Figure 9 of Patent Document 1, the motor has a motor housing on which a plurality of forward-tilting fins and a plurality of reverse-tilting fins are provided on its outer circumferential surface. The forward-tilting fins are tilted toward one side in the circumferential direction (for example, clockwise) toward the downstream axis of the rotation shaft. The reverse-tilting fins are tilted toward the other side in the circumferential direction (for example, counterclockwise) toward the downstream axis of the rotation shaft. Between the forward-tilting fins and the reverse-tilting fins, the direction of inclination toward the axis of the rotation shaft is opposite to that of the other.

[0006] Cooling air flows along the outer surface of the motor housing. Because the inclination directions of the forward-angled fins and the reverse-angled fins are opposite to those of the axis of rotation, the cooling air does not flow uniformly along the outer surface of the motor housing. As a result, parts of the motor housing are cooled strongly by the cooling air and parts are cooled weakly. Furthermore, the weakly cooled parts of the motor housing may not be cooled sufficiently. In addition, parts of the inverter device located downstream of the motor are also cooled strongly and weakly by the cooling air. Furthermore, the weakly cooled parts of the inverter device may not be cooled sufficiently. Thus, in the drive device described in Figure 9 of Patent Document 1, the cooling efficiency of the motor and inverter device is reduced due to the occurrence of weakly cooled parts.

[0007] In view of the above background, the present invention aims to efficiently cool two cylindrical drive units or electrical devices in a system in which two cylindrical drive units or electrical devices are arranged coaxially with each other. This will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the present invention provides a drive system (16) that drives a rotating shaft (33), comprising a cylindrical first drive unit (31) and a second drive unit (32) arranged coaxially with respect to each other, wherein the first drive unit has a first inlet (62A) formed on the opposite side from the second drive unit and a first outlet (63A) formed on the side of the second drive unit, and a first cooling passage (61A) extending spirally around the rotating shaft on the outer circumference of the first drive unit, and the first The second drive unit has a first heat dissipation fin (51A) that protrudes into the cooling passage and extends spirally along the first cooling passage, and the second drive unit has a second inlet (62B) formed on the side of the first drive unit and a second outlet (63B) formed on the side opposite to the first drive unit, and the second drive unit has a second cooling passage (61B) that extends spirally around the rotation axis on the outer circumference of the second drive unit and a second heat dissipation fin (51B) that protrudes into the second cooling passage and extends spirally along the second cooling passage.

[0009] In this embodiment, since the first cooling passage extends spirally around the outer periphery of the first drive unit, the refrigerant flows spirally along the first cooling passage around the outer periphery of the first drive unit. This allows the outer periphery of the first drive unit to be cooled evenly in the circumferential direction. Similarly, since the second cooling passage extends spirally around the outer periphery of the second drive unit, the refrigerant flows spirally along the second cooling passage around the outer periphery of the second drive unit. This allows the outer periphery of the second drive unit to be cooled evenly in the circumferential direction. Therefore, the first drive unit and the second drive unit can be efficiently cooled from their outer peripheries.

[0010] In the above embodiment, the first heat dissipation fin may extend spirally along the first cooling passage from the first inlet to the first outlet, and the second heat dissipation fin may extend spirally along the second cooling passage from the second inlet to the second outlet.

[0011] According to this embodiment, the outer periphery of the first drive unit and the outer periphery of the second drive unit can be reliably cooled to every corner. Therefore, the first drive unit and the second drive unit can be reliably and efficiently cooled.

[0012] In the above embodiment, the first drive unit has a first housing (43A) formed in a cylindrical shape on its outer circumference extending in the axial direction (X) of the rotation shaft, and a first duct (44A) provided on the outer circumference of the first housing, the first housing having the first heat dissipation fins, and the first duct having a cylindrical first outer cylinder portion (56A) spaced apart on the outer circumference of the first housing, and a first partition wall (57A) between the first outer cylinder portion and the first housing, extending spirally along the first heat dissipation fins from the first inlet to the first outlet, defining the first cooling passage. The second drive unit may have a second housing (43B) formed in a cylindrical shape on its outer circumference extending in the axial direction of the rotating shaft, and a second duct (44B) provided on the outer circumference of the second housing, wherein the second housing has the second heat dissipation fins, and the second duct may have a cylindrical second outer cylinder portion (56B) arranged at intervals on the outer circumference of the second housing, and a second partition wall (57B) between the second outer cylinder portion and the second housing, extending spirally along the second heat dissipation fins from the second inlet to the second outlet, defining the second cooling passage.

[0013] According to this embodiment, the first cooling passage and the second cooling passage can be formed with a simple configuration.

[0014] In the above embodiment, the first heat dissipation fin, the first partition wall, the second heat dissipation fin, and the second partition wall may extend in a spiral shape that is either right-handed or left-handed.

[0015] According to this embodiment, the first duct and the second duct can be manufactured in the same manner, thus facilitating the manufacture of the drive system.

[0016] In the above embodiment, the first heat dissipation fin and the first partition wall may extend in a right-handed or left-handed spiral, and the second heat dissipation fin and the second partition wall may extend in a right-handed or left-handed spiral.

[0017] According to this embodiment, the first heat dissipation fin 51A, the first helical groove 52A, the first partition wall 57A, the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B can be manufactured in the same manner, thus facilitating the manufacture of the drive system.

[0018] In the above embodiment, the first outer cylinder portion and the first partition wall may be formed integrally, and the second outer cylinder portion and the second partition wall may be formed integrally.

[0019] According to this embodiment, it becomes easier to assemble the first duct 44A to the first drive unit 31. Furthermore, it becomes easier to assemble the second duct 44B to the second drive unit 32. Therefore, the manufacturing of the drive system becomes easier.

[0020] In the above embodiment, the first heat dissipation fin, the first partition wall, the second heat dissipation fin, and the second partition wall may be formed in a spiral shape with the same radius and the same pitch as each other.

[0021] According to this embodiment, the first duct and the second duct can be manufactured in the same manner, thus facilitating the manufacture of the drive system.

[0022] In the above embodiment, the first drive unit may further include a first introduction passage (65A) extending in the axial direction of the rotating shaft on the outer periphery opposite to the second drive unit and connected to the first inlet, and a second introduction passage (65B) extending in the axial direction of the rotating shaft adjacent to the first introduction passage on the radially outer side of the rotating shaft and connected to the second inlet.

[0023] According to this aspect, the refrigerant flowing into the first introduction passage flows through the first cooling passage. Also, the refrigerant flowing into the second introduction passage flows through the second cooling passage. Therefore, the refrigerant flows into the first cooling passage and the second cooling passage in parallel. As a result, the refrigerant heated in the first cooling passage does not flow into the second cooling passage, so that the second drive unit can be surely and efficiently cooled.

[0024] In the above aspect, the first housing may have a first spiral groove (52A) formed on an outer peripheral surface and receiving a tip of the first partition wall, and the second housing may have a second spiral groove (52B) formed on an outer peripheral surface and receiving a tip of the second partition wall.

[0025] According to this aspect, it becomes easy to hold the first partition wall and the second partition wall at predetermined positions by the first spiral groove and the second spiral groove.

[0026] In order to solve the above problems, an aspect of the present invention is an electric system (16) including cylindrical first and second electric devices (31, 32) arranged coaxially with each other and driving a rotation shaft (34). The first electric device has a first inlet (62A) formed on a side opposite to the second electric device and a first outlet (63A) formed on the second electric device side, a first cooling passage (61A) extending spirally around the rotation shaft on an outer peripheral portion of the first electric device, and a first heat dissipation fin (51A) protruding into the first cooling passage and extending spirally along the first cooling passage. The second electric device has a second inlet (62B) formed on the first electric device side and a second outlet (63B) formed on a side opposite to the first electric device, a second cooling passage (61B) extending spirally around the rotation shaft on an outer peripheral portion of the second electric device, and a second heat dissipation fin (51B) protruding into the second cooling passage and extending spirally along the second cooling passage.

[0027] According to this aspect, since the first cooling passage extends spirally at the outer peripheral portion of the first electric device, the refrigerant flows spirally along the first cooling passage at the outer peripheral portion of the first electric device. Thereby, the outer peripheral portion of the first electric device can be cooled without circumferential deviation. Further, since the second cooling passage extends spirally at the outer peripheral portion of the second electric device, the refrigerant flows spirally along the second cooling passage at the outer peripheral portion of the second electric device. Thereby, the outer peripheral portion of the second electric device can be cooled without circumferential deviation. Therefore, the first electric device and the second electric device can be efficiently cooled from the outer peripheral portion.

Effect of the Invention

[0028] According to the above aspect, in a system in which two cylindrical drive units or electric devices are arranged coaxially with each other, the two drive units or electric devices can be efficiently cooled.

Brief Description of the Drawings

[0029] [Figure 1] Perspective view showing an aircraft according to the first embodiment [Figure 2] Partial cross-sectional view schematically showing a propulsion unit according to the first embodiment [Figure 3] Perspective view of a drive system according to the first embodiment [Figure 4] Perspective cross-sectional view of a drive system according to the first embodiment [Figure 5] Cross-sectional view of a first duct, a second duct, a first introduction duct, and a second introduction duct according to the first embodiment [Figure 6] Perspective cross-sectional view of a first duct, a second duct, a first introduction duct, and a second introduction duct according to the first embodiment [Figure 7] Schematic side view of a drive system according to the first embodiment [Figure 8] Schematic side view of a drive system according to the second embodiment [Figure 9] Perspective cross-sectional view of a first duct, a second duct, a first introduction duct, and a second introduction duct according to the second embodiment [Modes for carrying out the invention]

[0030] <<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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] <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.

[0035] The support 15 is fixed to the rear end of the fuselage 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 22 provided concentrically with the nacelle 20 and a plurality of spokes 23 extending radially from the outer circumferential surface of the hub 22 and connected to the inner circumferential surface of the nacelle 20.

[0036] <Drive System 16> As shown in Figure 2, the drive system 16 comprises a first drive unit 31, a second drive unit 32, a shaft 33 (rotating axis) extending in the front-rear direction and rotatably supported by the drive system 16, and a propeller 34 fixed to the rear of the shaft 33. The drive system 16 is housed in the nacelle 20. The drive system 16 is fixed to the hubs 22 of the front and rear mounting frames 21. The drive system 16 drives the shaft 33. The drive system 16 is one example of an electrical system.

[0037] The first drive unit 31 and the second drive unit 32 each support the shaft 33 so that it can rotate around its axis and drive the shaft 33 to rotate. The first drive unit 31 is fixed to the hub 22 of the front mount frame 21. The second drive unit 32 is fixed to the hub 22 of the rear mount frame 21.

[0038] The shaft 33 extends along its axial direction X (first direction). A conical front cover 36, which expands in diameter toward the rear, is fixed to the first end 33A (front end) of the shaft 33 on the first drive unit 31 side. The front cover 36 is positioned in front of the center of the propeller 34. A conical rear cover 37, which expands in diameter toward the front, is fixed to the second end 33B (rear end) of the shaft 33 on the second drive unit 32 side.

[0039] The propeller 34 is configured to rotate integrally with the shaft 33 as the shaft 33 rotates, thereby generating a propulsive airflow F (see Figure 7) that flows along the axial direction X (rearward). The propeller 34 generates a forward thrust force for the aircraft 1 by generating the propulsive airflow F.

[0040] <First drive unit 31, second drive unit 32> As shown in Figure 2, the first drive unit 31 and the second drive unit 32 each have an electric motor 41 that rotates the shaft 33 and a control device 42 that controls the operation of the electric motor 41, and rotatably support the shaft 33. The first drive unit 31 and the second drive unit 32 are formed in a cylindrical shape and are arranged coaxially with each other.

[0041] Figure 3 is a perspective view of the drive system 16. Figure 4 is a perspective cross-sectional view of the drive system 16. Figures 3 and 4 omit illustrations of components such as the propeller 34. As shown in Figures 3 and 4, the first drive unit 31 includes a first housing 43A, a first duct 44A, a first intake duct 45A connected to the first duct 44A, and a first cover 46A attached to the front side of the first housing 43A. The electric motor 41 and control device 42 of the first drive unit 31 are housed in the first housing 43A.

[0042] As shown in Figure 4, the first housing 43A is formed in a cylindrical shape extending in the axial direction X (front-to-back direction) of the shaft 33 on the outer circumference of the first drive unit 31. The first housing 43A has a first heat dissipation fin 51A that extends in a right-handed spiral shape around the shaft 33 on the outer circumference, and a first helical groove 52A that extends in a right-handed spiral shape around the shaft 33 on the outer circumference. The first heat dissipation fin 51A is formed in a plate shape that extends radially outward from the first drive unit 31. The first helical groove 52A is a groove that is recessed radially inward from the first drive unit 31 in the first housing 43A. The first heat dissipation fin 51A and the first helical groove 52A extend spirally parallel to each other.

[0043] The first duct 44A is formed in a cylindrical shape extending in the axial direction X (front-to-back direction) of the shaft 33 on the outer circumference of the first housing 43A. The first duct 44A has a cylindrical first outer cylinder portion 56A arranged at intervals on the outer circumference of the first housing 43A, and a first partition wall 57A extending in a right-handed spiral along the first heat dissipation fin 51A between the first outer cylinder portion 56A and the first housing 43A. The first partition wall 57A is formed integrally with the first outer cylinder portion 56A and is formed in a plate shape extending radially inward from the inner circumferential surface of the first outer cylinder portion 56A. Note that the first outer cylinder portion 56A and the first partition wall 57A may be formed separately.

[0044] Figure 5 is a cross-sectional view of the first duct 44A, the second duct 44B, the first inlet duct 45A, and the second inlet duct 45B. The tip of the first bulkhead 57A protrudes into the first helical groove 52A. The first heat dissipation fin 51A, the first helical groove 52A, and the first bulkhead 57A extend spirally parallel to each other. Therefore, the first heat dissipation fin 51A, the first helical groove 52A, and the first bulkhead 57A extend in a right-handed spiral with the same radius and the same pitch. The pitch is the height of one period of the spiral. In other words, the pitch is the amount of displacement in the axial direction X when a point completes one revolution on the spiral.

[0045] As shown in Figure 4, the first cover 46A is attached to the front of the first housing 43A and closes the front opening of the first housing 43A. The first cover 46A also has an opening in the center through which the shaft 33 is inserted. The first cover 46A is fixed to the first housing 43A. Bolts and nuts may be used to fix the first cover 46A to the first housing 43A, rivets may be used, adhesive may be used, welding may be used, or a combination of these may be used. The first cover 46A and the first housing 43A may also be formed as a single unit.

[0046] As shown in Figure 5, the tip of the first bulkhead 57A of the first duct 44A protrudes into the first helical groove 52A, thereby attaching the first duct 44A to the first housing 43A. Alternatively, the first cover 46A may have a projection extending radially outward, to which the first duct 44A may be fixed. Bolts and nuts may be used to fix the projection of the first cover 46A to the first duct 44A, rivets may be used, adhesives may be used, welding may be used, or a combination of these may be used.

[0047] As shown in Figure 5, a first cooling passage 61A is formed between the first housing 43A and the first duct 44A. The first cooling passage 61A has a first inlet 62A formed on the side opposite the second drive unit 32 and a first outlet 63A formed on the side of the second drive unit 32. The first inlet 62A faces the axial direction X (rearward) of the shaft 33. As shown in Figure 4, the first outlet 63A faces the circumferential direction of the first duct 44A.

[0048] As shown in Figure 5, the first partition wall 57A defines the first cooling passage 61A extending from the first inlet 62A to the first outlet 63A. As a result, the first cooling passage 61A extends in a right-handed spiral shape around the shaft 33 on the outer circumference of the first drive unit 31. The first heat dissipation fin 51A protrudes into the first cooling passage 61A and extends spirally along the first cooling passage 61A from the first inlet 62A to the first outlet 63A.

[0049] As shown in Figures 3 to 5, the first inlet duct 45A is formed in a cylindrical shape extending in the axial direction X (forward) of the shaft 33 from the opposite side of the second drive unit 32 on the outer periphery of the first drive unit 31. As shown in Figure 5, the first inlet duct 45A is formed integrally with the first duct 44A. The first inlet duct 45A may be formed separately from the first duct 44A. The end of the first inlet duct 45A on the second drive unit 32 side (rear side) is connected to the first inlet 62A. Inside the first inlet duct 45A, a first inlet passage 65A is formed. The first inlet passage 65A extends in the axial direction X (forward) of the shaft 33 from the opposite side of the second drive unit 32 on the outer periphery of the first drive unit 31, and its rear end is connected to the first inlet 62A.

[0050] As shown in Figure 4, the second drive unit 32 includes a second housing 43B, a second duct 44B, a second introduction duct 45B connected to the second duct 44B, and a second cover 46B attached to the rear side of the second housing 43B.

[0051] The second housing 43B is formed in a cylindrical shape extending in the axial direction X (front-rear direction) of the shaft 33 on the outer circumference of the second drive unit 32. The second housing 43B has a second heat dissipation fin 51B that extends in a right-handed spiral shape around the shaft 33 on the outer circumference, and a second helical groove 52B that extends in a right-handed spiral shape around the shaft 33 on the outer circumference. The second heat dissipation fin 51B is formed in a plate shape that extends radially outward from the second drive unit 32. The second helical groove 52B is a groove that is recessed radially inward from the second drive unit 32 in the second housing 43B. The second heat dissipation fin 51B and the second helical groove 52B extend spirally parallel to each other.

[0052] The second duct 44B is formed in a cylindrical shape extending in the axial direction X (front-to-back direction) of the shaft 33 on the outer circumference of the second housing 43B. The second duct 44B has a cylindrical second outer cylinder portion 56B arranged at intervals on the outer circumference of the second housing 43B, and a second partition wall 57B that extends in a right-handed spiral along the second heat dissipation fin 51B between the second outer cylinder portion 56B and the second housing 43B. The second partition wall 57B is formed integrally with the second outer cylinder portion 56B and is formed in a plate shape extending radially inward from the second outer cylinder portion 56B to the second drive unit 32. The second outer cylinder portion 56B and the second partition wall 57B may be formed separately.

[0053] As shown in Figure 5, the tip of the second partition wall 57B protrudes into the second helical groove 52B. The second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B extend spirally parallel to each other. Therefore, the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B extend in a right-handed spiral with the same radius and the same pitch as each other.

[0054] As shown in Figure 4, the second cover 46B is attached to the rear side of the second housing 43B, closing the rear opening of the second housing 43B. The second cover 46B also has an opening in the center through which the shaft 33 is inserted. The second cover 46B is fixed to the second housing 43B. Bolts and nuts may be used to fix the second cover 46B to the second housing 43B, rivets may be used, adhesive may be used, welding may be used, or a combination of these may be used. The second cover 46B and the second housing 43B may also be formed as a single unit.

[0055] As shown in Figure 5, the tip of the second bulkhead 57B of the second duct 44B protrudes into the second helical groove 52B, thereby attaching the second duct 44B to the second housing 43B. Alternatively, the second cover 46B may have a projection extending radially outward, to which the second duct 44B may be fixed. Bolts and nuts may be used to fix the projection of the second cover 46B to the second duct 44B, rivets may be used, adhesives may be used, welding may be used, or a combination of these may be used.

[0056] A second cooling passage 61B is formed between the second housing 43B and the second duct 44B. The second cooling passage 61B has a second inlet 62B formed on the side of the first drive unit 31 and a second outlet 63B formed on the side opposite the first drive unit 31. As shown in Figure 4, the second outlet 63B faces the circumferential direction of the second duct 44B.

[0057] As shown in Figure 5, the second partition wall 57B defines the second cooling passage 61B from the second inlet 62B to the second outlet 63B. As a result, the second cooling passage 61B extends in a right-handed spiral shape around the shaft 33 on the outer circumference of the second drive unit 32. The second heat dissipation fin 51B protrudes into the second cooling passage 61B and extends spirally along the second cooling passage 61B from the second inlet 62B to the second outlet 63B.

[0058] As shown in Figures 3 to 5, the second introduction duct 45B is formed as a cylindrical shape extending from the first drive unit 31 side in the axial direction X (forward) of the shaft 33 on the outer circumference of the second drive unit 32. The second introduction duct 45B is formed integrally with the second duct 44B. The second introduction duct 45B may be formed separately from the second duct 44B.

[0059] As shown in Figure 4, the second inlet duct 45B is adjacent to the first inlet duct 45A on the radially outer side of the shaft 33 and extends in the axial direction X (forward) of the shaft 33. As shown in Figure 5, the rear end of the second inlet duct 45B is connected to the second inlet 62B. A second inlet passage 65B is formed inside the second inlet duct 45B. The second inlet passage 65B is adjacent to the first inlet passage 65A on the radially outer side of the shaft 33 and extends in the axial direction X of the shaft 33 and is connected to the second inlet 62B.

[0060] Figure 6 is a perspective cross-sectional view of the first duct 44A, the first inlet duct 45A, the second duct 44B, and the second inlet duct 45B. The first duct 44A defines the first cooling passage 61A, and the first inlet passage 65A (see Figure 5) is formed inside the first inlet duct 45A. As described below, the cooling air A (refrigerant) flows into the first inlet passage 65A, and then flows from the first inlet passage 65A into the first cooling passage 61A. In the first cooling passage 61A, the cooling air A flows in a right-handed spiral along the first cooling passage 61A. The second duct 44B defines the second cooling passage 61B, and the second inlet passage 65B is formed inside the second inlet duct 45B. The cooling air B flows into the second inlet passage 65B, and then flows from the second inlet passage 65B into the second cooling passage 61B. The cooling air B flows in a right-handed spiral along the second cooling passage 61B in the second cooling passage 61B.

[0061] Figure 7 is a schematic side view of the drive system 16. As shown in Figure 7, the drive system 16 rotates the shaft 33 and the propeller 34 together, generating a propulsion airflow F from the propeller 34 that flows along the axial direction X (rearward). As a result, a portion of the propulsion airflow F flows as cooling airflow A into the first intake passage 65A of the first intake duct 45A, and further into the first cooling passage 61A. In the first cooling passage 61A, the cooling airflow A flows in a right-handed spiral around the shaft 33 on the outer circumference of the first drive unit 31. This cools the first drive unit 31.

[0062] Furthermore, a portion of the propulsion air F flows into the second intake passage 65B of the second intake duct 45B as cooling air B, and then flows into the second cooling passage 61B. In the second cooling passage 61B, the cooling air B flows in a right-handed spiral around the shaft 33 along the second cooling passage 61B on the outer circumference of the second drive unit 32. This cools the second drive unit 32.

[0063] Next, we will explain the effects of the drive system 16.

[0064] The first drive unit 31 (electrical system) has a first cooling passage 61A and a second cooling passage 61B. Since the first cooling passage 61A extends spirally around the outer circumference of the first drive unit 31, air (refrigerant) flows spirally along the first cooling passage 61A around the outer circumference of the first drive unit 31. This allows the outer circumference of the first drive unit 31 to be cooled evenly in the circumferential direction. Similarly, since the second cooling passage 61B extends spirally around the outer circumference of the second drive unit 32, air flows spirally along the second cooling passage 61B around the outer circumference of the second drive unit 32. This allows the outer circumference of the second drive unit 32 to be cooled evenly in the circumferential direction. Therefore, the first drive unit 31 (first electrical device) and the second drive unit 32 (first electrical device) can be efficiently cooled from the outer circumference.

[0065] The first heat dissipation fin 51A extends spirally along the first cooling passage 61A from the first inlet 62A to the first outlet 63A. The second heat dissipation fin 51B extends spirally along the second cooling passage 61B from the second inlet 62B to the second outlet 63B. This ensures that the outer periphery of the first drive unit 31 and the outer periphery of the second drive unit 32 are cooled thoroughly. As a result, the first drive unit 31 and the second drive unit 32 can be cooled efficiently and reliably.

[0066] The first drive unit 31 has a first duct 44A having a first outer cylinder portion 56A and a first partition wall 57A. The second drive unit 32 has a second duct 44B having a second outer cylinder portion 56B and a second partition wall 57B. This allows the first cooling passage 61A and the second cooling passage 61B to be formed with a simple configuration.

[0067] The first partition wall 57A, the first heat dissipation fin 51A, the second partition wall 57B, and the second heat dissipation fin 51B extend in a right-handed spiral. This allows the first duct 44A and the second duct 44B to be manufactured similarly, thus facilitating the manufacture of the drive system 16. Furthermore, the fluid analysis and design of the first partition wall 57A and the first heat dissipation fin 51A can be performed similarly to the fluid analysis and design of the second partition wall 57B and the second heat dissipation fin 51B, thus facilitating the design of the drive system 16.

[0068] Since the first outer cylinder portion 56A and the first partition wall 57A are integrally formed in the first duct 44A, it becomes easy to assemble the first duct 44A to the first drive unit 31. Also, since the second outer cylinder portion 56B and the second partition wall 57B are integrally formed in the second duct 44B, it becomes easy to assemble the second duct 44B to the second drive unit 32. Therefore, the manufacturing of the drive system 16 becomes easier.

[0069] The first heat dissipation fin 51A, the first partition wall 57A, the second partition wall 57B, and the second heat dissipation fin 51B are formed in a spiral shape with the same radius and the same pitch as each other. This allows the first duct 44A and the second duct 44B to be manufactured in the same manner, thus facilitating the manufacture of the drive system 16.

[0070] The drive system 16 has a first intake passage 65A and a second intake passage 65B. As a result, air (cooling air A) flowing into the first intake passage 65A circulates through the first cooling passage 61A. Similarly, air (cooling air B) flowing into the second intake passage 65B circulates through the second cooling passage 61B. Therefore, air flows into the first cooling passage 61A and the second cooling passage 61B in parallel. This prevents air heated in the first cooling passage 61A from flowing into the second cooling passage 61B, thus ensuring that the second drive unit 32 is cooled reliably and efficiently.

[0071] The first housing 43A having a first helical groove 52A makes it easier to hold the first bulkhead 57A in a predetermined position. The second housing 43B having a second helical groove 52B makes it easier to hold the second bulkhead 57B in a predetermined position.

[0072] <<Second Embodiment>> Figure 8 is a schematic side view of the drive system 16 according to the second embodiment. As shown in Figure 8, in the drive system 16 of the second embodiment, similar to the first embodiment, the first heat dissipation fin 51A, the first helical groove 52A, and the first partition wall 57A extend in a right-handed spiral (either right-handed or left-handed). On the other hand, the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B extend in a left-handed spiral (the other of right-handed or left-handed). In the description of the drive system 16 of the second embodiment, the same or similar components as those in the drive system 16 of the first embodiment are denoted by the same reference numerals, and redundant detailed descriptions are omitted.

[0073] Figure 9 is a perspective cross-sectional view of the first duct 44A, the first inlet duct 45A, the second duct 44B, and the second inlet duct 45B. The first duct 44A defines the first cooling passage 61A, and the first inlet passage 65A is formed inside the first inlet duct 45A. As described below, the cooling air A (refrigerant) flows into the first inlet passage 65A, and then flows from the first inlet passage 65A into the first cooling passage 61A. In the first cooling passage 61A, the cooling air A flows in a right-handed spiral along the first cooling passage 61A. The second duct 44B defines the second cooling passage 61B, and the second inlet passage 65B is formed inside the second inlet duct 45B. The cooling air B flows into the second inlet passage 65B, and then flows from the second inlet passage 65B into the second cooling passage 61B. The cooling air B flows in a left-handed spiral along the second cooling passage 61B in the second cooling passage 61B.

[0074] The first heat dissipation fin 51A, the first helical groove 52A, the first partition wall 57A, the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B extend in a helical shape. Therefore, since the first heat dissipation fin 51A, the first helical groove 52A, the first partition wall 57A, the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B can be manufactured in the same manner, the manufacturing of the drive system 16 becomes easier.

[0075] The first heat dissipation fin 51A, the first partition wall 57A, the second partition wall 57B, and the second heat dissipation fin 51B are formed in a spiral shape with the same radius and pitch as each other. Fluid analysis and design of the first partition wall 57A and the first heat dissipation fin 51A can be performed in the same manner as fluid analysis and design of the second partition wall 57B and the second heat dissipation fin 51B. This facilitates the design and manufacture of the drive system 16.

[0076] Furthermore, the first duct 44A and the second duct 44B can be assembled to the first housing 43A and the second housing 43B as follows. First, the first housing 43A and the second housing 43B are connected. Next, the first duct 44A and the second duct 44B are rotated spirally in the same direction (for example, clockwise) from each end of the connected first housing 43A and the second housing 43B, thereby assembling the first duct 44A and the second duct 44B to the connected first housing 43A and the second housing 43B. This makes it easier to assemble the first duct 44A and the second duct 44B, and thus facilitates the manufacture of the drive system 16.

[0077] 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, the drive system 16 does not have to include a propeller 34. The propeller 34 is configured to rotate integrally with the shaft 33 as the shaft 33 rotates, thereby generating a propulsive airflow F (see Figure 7) that flows along the axial direction X (rearward), but the direction of the propulsive airflow F is not limited to the rear. For example, the propeller 34 may be configured to generate a propulsive airflow that flows along the forward direction. Also, there are no restrictions on the orientation of the drive system 16. In the first and second embodiments, air was used as a refrigerant, but the refrigerant can be any fluid. The refrigerant can be a gas or a liquid.

[0078] Furthermore, the first drive unit 31 and the second drive unit 32 do not have a built-in control device 42, and the control devices that control the electric motors 41 of the first drive unit 31 and the second drive unit 32 may be externally attached to the first drive unit 31 and the second drive unit 32. The first drive unit 31 may be an electric motor, and the second drive unit 32 may be a control device that controls the electric motor of the first drive unit 31.

[0079] The first housing 43A does not need to be provided with the first helical groove 52A. Similarly, the second housing 43B does not need to be provided with the second helical groove 52B. Furthermore, the first drive unit 31 does not need to be provided with the first inlet duct 45A. Also, the second drive unit 32 does not need to be provided with the second inlet duct 45B.

[0080] The first heat dissipation fin 51A does not have to extend spirally along the first cooling passage 61A from the first inlet 62A to the first outlet 63A. Similarly, the second heat dissipation fin 51B does not have to extend spirally along the second cooling passage 61B from the second inlet 62B to the second outlet 63B.

[0081] The first heat dissipation fin 51A, the first helical groove 52A, and the first partition wall 57A may extend in a left-handed spiral, while the second heat dissipation fin 51B, the second helical groove 52B, and the second partition wall 57B may extend in a right-handed spiral. The first heat dissipation fin 51A, the first partition wall 57A, the second heat dissipation fin 51B, and the second partition wall 57B may extend in a left-handed spiral.

[0082] The first heat dissipation fin 51A and the first partition wall 57A, and the second partition wall 57B and the second heat dissipation fin 51B do not necessarily have to be formed in a spiral shape with the same radius and the same pitch. For example, the first heat dissipation fin 51A and the first partition wall 57A, and the second partition wall 57B and the second heat dissipation fin 51B may be formed in a spiral shape with different pitches. [Explanation of symbols]

[0083] 16: Drive System 31: First drive unit 32: Second drive unit 33: Shaft (rotation axis) 43A: Housing 1 43B: Second Housing 44A: First duct 44B: Second duct 51A: First heat dissipation fin 51B: Second heat dissipation fin 52A: 1st spiral groove 52B: 2nd spiral groove 56A: First outer cylinder section 56B: Second outer cylinder section 57A: 1st bulkhead 57B:Second bulkhead 61A: 1st cooling passage 61B:Second cooling passage 62A: First inlet 62B: 2nd inlet 63A: 1st outlet 63B: 2nd outlet 65A: First entrance passage 65B: 2nd introduction passage X: Axial direction

Claims

1. A drive system for driving a rotating shaft, comprising a first drive unit and a second drive unit, both cylindrical in shape and arranged coaxially with each other, The first drive unit is, A first cooling passage has a first inlet formed on the opposite side of the second drive unit and a first outlet formed on the side of the second drive unit, and extends spirally around the rotation axis on the outer circumference of the first drive unit, It has a first heat dissipation fin that protrudes into the interior of the first cooling passage and extends spirally along the first cooling passage, The second drive unit is, The second cooling passage has a second inlet formed on the side of the first drive unit and a second outlet formed on the side opposite to the first drive unit, and extends spirally around the rotation axis on the outer circumference of the second drive unit, A drive system having a second heat dissipation fin that protrudes into the interior of the second cooling passage and extends spirally along the second cooling passage.

2. The first heat dissipation fin extends spirally along the first cooling passage from the first inlet to the first outlet, The drive system according to claim 1, wherein the second heat dissipation fin extends spirally along the second cooling passage from the second inlet to the second outlet.

3. The first drive unit comprises a first housing formed in a cylindrical shape extending in the axial direction of the rotation shaft on its outer circumference, and a first duct provided on the outer circumference of the first housing. The first housing has a first heat dissipation fin, The first duct comprises a cylindrical first outer cylinder portion arranged at intervals around the outer circumference of the first housing, and a first partition wall between the first outer cylinder portion and the first housing, extending spirally along the first heat dissipation fins from the first inlet to the first outlet, thereby defining the first cooling passage. The second drive unit comprises a second housing formed in a cylindrical shape extending in the axial direction of the rotation shaft on its outer circumference, and a second duct provided on the outer circumference of the second housing. The second housing has the second heat dissipation fin, The drive system according to claim 1, wherein the second duct comprises a cylindrical second outer cylinder portion arranged at intervals around the outer circumference of the second housing, and a second partition wall between the second outer cylinder portion and the second housing, extending spirally along the second heat dissipation fins from the second inlet to the second outlet, thereby defining the second cooling passage.

4. The drive system according to claim 3, wherein the first heat dissipation fin, the first partition wall, the second heat dissipation fin, and the second partition wall extend in a spiral shape that is either right-handed or left-handed.

5. The first heat dissipation fin and the first partition wall extend in a spiral shape that is either right-handed or left-handed, The drive system according to claim 3, wherein the second heat dissipation fin and the second partition wall extend in the right-handed and left-handed spiral directions, respectively.

6. The first outer cylinder portion and the first partition wall are formed integrally, The drive system according to claim 3, wherein the second outer cylinder portion and the second partition wall are integrally formed.

7. The drive system according to claim 3 or 4, wherein the first heat dissipation fin, the first partition wall, the second heat dissipation fin, and the second partition wall are formed in a spiral shape with the same radius and the same pitch as each other.

8. A first introduction passage extends in the axial direction of the rotating shaft on the outer periphery of the first drive unit, opposite to the second drive unit, and is connected to the first inlet. The drive system according to claim 3, further comprising: a second introduction passage adjacent to the first introduction passage on the radially outer side of the rotating shaft, extending in the axial direction of the rotating shaft and connected to the second inlet.

9. The first housing has a first helical groove formed on its outer surface that receives the tip of the first partition wall, The drive system according to claim 3, wherein the second housing has a second helical groove formed on its outer surface for receiving the tip of the second partition wall.

10. An electrical system comprising a first and second cylindrical electrical device arranged coaxially with respect to a rotating shaft, The first electrical device is A first cooling passage has a first inlet formed on the opposite side of the second electrical device and a first outlet formed on the side of the second electrical device, and extends spirally around the rotation axis on the outer circumference of the first electrical device, It has a first heat dissipation fin that protrudes into the interior of the first cooling passage and extends spirally along the first cooling passage, The second electrical device, The second cooling passage has a second inlet formed on the side of the first electrical device and a second outlet formed on the side opposite to the first electrical device, and extends spirally around the rotation axis on the outer circumference of the second electrical device, An electrical system having a second heat dissipation fin that protrudes into the interior of the second cooling passage and extends spirally along the second cooling passage.

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