Electric fan and electric aircraft

Abstract

To provide an electric fan which has a simpler structure and achieves higher cooling performance, and to provide an electric aircraft.SOLUTION: An electric fan includes: an electric motor having an output shaft extending along an axis and a cylindrical housing centered on the axis; an inner duct provided at the downstream side of the electric motor; multiple blades attached to the output shaft; and a cooling member having fins provided on an outer peripheral surface of the housing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electric fan and an electric aircraft. [Background technology]

[0002] In recent years, there has been active research and development into electric aircraft that use electric fans to generate propulsion. An electric fan mainly comprises an electric motor, a plurality of blades that are driven to rotate by the motor, and a cooling device for cooling the motor. For example, Patent Document 1 listed below discloses a so-called liquid-cooled mechanism that uses a cooling medium as an example of a cooling device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 172102 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a liquid cooling medium is used as described above, sealing devices to prevent leakage from various parts and a large heat exchanger for exchanging heat between the cooling medium and the outside air are required, which leads to a complicated device and increased costs.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an electric fan and an electric aircraft that have a simpler structure and higher cooling performance. [Means for solving the problem]

[0006] In order to solve the above problems, the electric fan according to the present disclosure includes an output shaft extending along an axis, a rotor core attached to an outer peripheral surface of the output shaft, a stator core covering the rotor core from the outer peripheral side, and a cylindrical stator core centered on the axis. The stator core is fitted onto the inner peripheral surface of thean electric motor having a housing; before The output shaft on one side in the axial direction of With multiple blades attached an inner duct having an outer circumferential surface extending from the outer circumferential surface of the housing to the other side in the axial direction, the inner duct gradually decreasing in diameter from the one side to the other side in the axial direction; a cooling member having a plurality of fins provided on the outer peripheral surface of the housing; An intake port is formed on one axial side of the housing to take in the air compressed by the blades toward the rotor core and the stator core inside the housing, and an exhaust port is formed on the other axial end of the inner duct to discharge the air circulated through the intake port, and the fins extend from the rear side to the front side in the rotation direction of the blades as they move from one axial side to the other axial side. .

[0007] An electric aircraft according to the present disclosure includes the electric fan described above and an airframe to which the electric fan is attached. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an electric fan and an electric aircraft that have a simpler structure and higher cooling performance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic plan view showing the configuration of an electric aircraft according to a first embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view showing a configuration of an electric fan according to a first embodiment of the present disclosure. [Figure 3] 1 is a cross-sectional view of a cooling member according to a first embodiment of the present disclosure, viewed from an axial direction. [Figure 4] FIG. 2 is a view of a cooling member according to the first embodiment of the present disclosure as viewed from the radial outside. [Figure 5] FIG. 10 is a view of a cooling member and blades according to a second embodiment of the present disclosure, viewed from the radially outer side. [Figure 6] FIG. 10 is a cross-sectional view of a fin according to a second embodiment of the present disclosure, illustrating the air flow around the fin. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an electric fan according to a third embodiment of the present disclosure. [Figure 8] FIG. 11 is a view of a cooling member and blades according to a third embodiment of the present disclosure, viewed from the radially outer side. [Figure 9] 10 is a graph showing the relationship between the axial position on the outer surface of the electric fan according to the third embodiment of the present disclosure, and the circumferential velocity of the airflow and the static pressure. [Figure 10] FIG. 10 is a diagram showing a modified example of the electric fan common to each embodiment of the present disclosure, as viewed from the axial direction of the electric fan and the fuselage. [Figure 11] FIG. 10 is a cross-sectional view showing a first modified example of a fin common to each embodiment of the present disclosure. [Figure 12] FIG. 10 is a cross-sectional view showing a second modified example of a fin common to each embodiment of the present disclosure. [Figure 13] FIG. 10 is a cross-sectional view showing a third modified example of a fin common to each embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment An electric aircraft 1 and an electric fan 20 according to a first embodiment of the present disclosure will now be described with reference to FIGS. 1 to 4. FIG.

[0011] (Electric aircraft configuration) As shown in Fig. 1, the electric aircraft 1 includes an airframe 10 and a plurality of electric fans 20. The airframe 10 includes an airframe body 11 and a plurality of wings 12. As an example, the airframe body 11 has a streamlined shape extending in the direction of travel, and has space formed inside for carrying a pilot and passengers. In addition, landing gear (not shown) is attached to the lower part of the airframe body 11.

[0012] One or more wings 12 are provided on each side of the aircraft body 11 in the width direction. The wings 12 have an airfoil-shaped cross section to generate lift when the electric aircraft 1 flies horizontally. Furthermore, in this embodiment, as an example, each wing 12 is provided with a plurality (two on each side) of electric fans 20. Note that the electric fans 20 may be provided on the aircraft body 11 instead of on the wings 12. The electric fans 20 are supported in a state in which their thrust direction can be changed. That is, during vertical takeoff and landing, the thrust direction is vertically downward. On the other hand, during horizontal flight, the thrust direction can be made horizontal.

[0013] (Electric fan configuration) Next, a detailed description will be given of the configuration of the electric fan 20. As shown in Fig. 2, the electric fan 20 includes an electric motor 21, an inner duct 22, an outer duct 23, a propeller 24, and a cooling member 25.

[0014] The electric motor 21 has an output shaft 31, a rotor core 32, a stator core 33, a housing 34, and a bearing device 35. The output shaft 31 is columnar and extends along an axis O. The output shaft 31 is supported by the bearing device 35 at a midpoint in the direction of extension so as to be rotatable about the axis O. Specifically, the bearing device 35 may be a journal bearing that supports a load in the radial direction, or a thrust bearing that supports a load in the direction of the axis O, as appropriate.

[0015] A rotor core 32 is provided on the outer peripheral surface of the output shaft 31. The rotor core 32 has a plurality of permanent magnets. The rotor core 32 is covered by a stator core 33 with a gap between them from the outer periphery. The stator core 33 has a plurality of coils. When a current is supplied to the coils, an electromagnetic force is generated between the coils and the permanent magnets, and rotational energy is imparted to the rotor core 32 and the output shaft 31. In other words, the output shaft 31 is driven to rotate around the axis O.

[0016] The stator core 33 is covered from the outer periphery by a housing 34. The housing 34 has a cylindrical shape centered on an axis O. As an example, the stator core 33 is fixed to the inner periphery of the housing 34 in a tight fit state by shrink fitting or the like.

[0017] An inner duct 22 is provided on the other side of the electric motor 21 in the direction of the axis O. In the following description, the side on which the inner duct 22 is located as seen from the electric motor 21 may be referred to as the "downstream side," and the opposite side in the direction of the axis O may be referred to as the "upstream side." The inner duct 22 has a circular cross-sectional shape centered on the axis O. The diameter of the inner duct 22 gradually decreases from the upstream side to the downstream side. A space is formed inside the inner duct 22.

[0018] The electric motor 21 and inner duct 22 are covered from the outer peripheral side by an outer duct 23. The outer duct 23 is supported from the radially inner side by, for example, a plurality of struts 26 that protrude from the outer peripheral surface of a housing 34 of the electric motor 21. The struts 26 are arranged at intervals in the circumferential direction. An air flow path 80 is formed between the outer duct 23 and the inner duct 22.

[0019] A propeller 24 is attached to one side (upstream side) of the output shaft 31 of the electric motor 21 in the direction of the axis O. The propeller 24 has a spinner 41 and a plurality of blades 42. The spinner 41 is fixed to the upstream end of the output shaft 31. The spinner 41 has a pointed shape that is convex toward the upstream side. The spinner 41 has a circular shape when viewed from the direction of the axis O. A plurality of blades 42 are provided on the outer circumferential surface of the spinner 41 and are arranged at equal intervals in the circumferential direction.

[0020] Each blade 42 extends radially outward from the outer peripheral surface of the spinner 41. When viewed radially, each blade 42 has an airfoil-shaped cross section. Each blade 42 is fixed to the spinner 41 in a twisted state around a central axis extending radially (a pitch is added). Therefore, when the blades 42 rotate in conjunction with the rotation of the output shaft 31, air is compressed and sent from the upstream side to the downstream side. This air flow is released downstream from the air flow path 80 described above, generating thrust.

[0021] (Configuration of cooling components) The electric motor 21 is provided with a cooling member 25. The cooling member 25 has a plurality of fins 51. As shown in FIG. 3, these fins 51 protrude radially outward from the outer peripheral surface of the housing 34 of the electric motor 21. The cross section of each fin 51 as viewed from the direction of the axis O is rectangular. A plurality of such fins 51 are arranged at equal intervals in the circumferential direction. The radial dimensions of the plurality of fins 51 are the same. Furthermore, as shown in FIG. 4, each fin 51 extends parallel to the direction of the axis O.

[0022] (Action and effect) In recent years, there has been active research and development into electric aircraft 1 that obtains propulsion power from an electric fan 20. When an electric motor 21 rotates, heat is generated due to its internal resistance. If this heat increases, normal operation of the electric motor 21 is hindered. Therefore, conventional electric fans 20 generally use a so-called liquid-cooled mechanism that uses a cooling medium as a cooling mechanism for the electric motor 21.

[0023] However, when a liquid cooling medium is used as described above, sealing devices to prevent leakage from various parts and a large heat exchanger to exchange heat between the cooling medium and the outside air are required, which leads to a complicated device and increased costs. Therefore, in this embodiment, the cooling member 25 having fins 51 is used as described above.

[0024] According to the above configuration, heat from the electric motor 21 is dissipated to the outside (i.e., into the atmosphere) via the fins 51 of the cooling member 25. In other words, the heat transferred to the fins 51 through the housing 34 is exchanged with the outside air, thereby lowering the temperature of the fins 51 themselves. Therefore, the heat from the electric motor 21 is less likely to accumulate inside the electric motor 21. As a result, the electric motor 21 can be cooled efficiently.

[0025] Furthermore, with the above-described configuration, each fin 51 extends in the direction of the axis O. Here, the flow direction of the air compressed and sent by the blades 42 provided upstream of the fins 51 is inclined (has a deflection angle) with respect to the axis O. When the air having this deflection angle flows into the spaces between the fins 51 extending in the direction of the axis O, the flow direction of the air is straightened in the direction of the axis O. In other words, the air is straightened toward the thrust direction (propulsion direction) of the electric fan 20. This makes it possible to cool the electric motor 21 while further increasing the thrust force of the electric fan 20.

[0026] In particular, with the above-described configuration, there is no need to supply a cooling medium from an external source to cool the electric motor 21, nor is there any need to provide a sealing member or the like to prevent leakage of the cooling medium, making it possible to provide an electric fan 20 with even higher cooling performance with an even simpler structure.

[0027] The first embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0028] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Figures 5 and 6. Note that the same components as those in the first embodiment above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0029] As shown in FIG. 5, in this embodiment, the extending direction and shape of the fin 151 are different from those of the first embodiment. Specifically, the fin 151 has an airfoil-shaped cross section when viewed from the radial direction. The surface of the fin 151 facing rearward in the rotation direction of the blade 42 (arrow R in FIG. 5) is the pressure surface 61, and the surface facing forward in the rotation direction of the blade 42 is the back surface 62. The pressure surface 61 is concave in a curved shape toward the front side in the rotation direction. The back surface 62 is curved in a curved shape so as to be convex toward the front side in the rotation direction. In addition, the upstream end of the fin 151 is arc-shaped. On the other hand, the downstream end of the fin 151 is pointed.

[0030] In this way, because the fins 151 have a wing-shaped cross-sectional shape, the flow path formed between a pair of adjacent fins 151 has a flow path cross-sectional area that first decreases and then increases again as it moves from the upstream side to the downstream side.

[0031] Furthermore, the upstream ends of the fins 151 extend toward the upstream side of the flow direction (arrow A) of the air compressed by the blades 42. In other words, the upstream regions of the flow paths formed between the fins 151 extend substantially parallel to the flow direction of the air compressed by the blades 42. On the other hand, the downstream ends of the fins 151 extend substantially parallel to the direction of the axis O. In other words, the downstream regions of the flow paths formed between the fins 151 extend substantially parallel to the direction of the axis O.

[0032] 6, each fin 151 has a rectangular cross-sectional shape when viewed from the direction of the axis O. That is, the circumferential dimension of the fin 151 is constant over the entire radial area. In other words, the fin 151 has a thickness in the circumferential direction. Therefore, the fin 151 has a surface (outer end surface 63) facing radially outward.

[0033] (Action and effect) According to the above configuration, one end of the fin 151 in the direction of the axis O extends toward the upstream side in the flow direction of the air compressed by the blades 42. This allows the air to flow smoothly along the surfaces of the blades 42. This reduces the possibility that the air will separate from the surfaces of the blades 42. Furthermore, because separation is less likely to occur, it also reduces the possibility that vortices will be generated between the fins 151. As a result, it is possible to further improve the cooling performance for the electric motor 21.

[0034] Furthermore, because the fins 151 have an airfoil-shaped cross section, the spacing between the fins 151 shrinks once and then expands again. This causes the flow paths between the fins 151 to generate a diffuser effect. In other words, the air flow velocity decreases downstream of the flow paths between the fins 151, reducing the dynamic pressure, allowing the static pressure to recover. This further reduces the possibility of flow separation occurring on the surfaces of the fins 151.

[0035] Furthermore, with the above configuration, since the fins 151 have outer end surfaces 63 facing radially outward, a pressure difference occurs between both sides of the fins 151 in the plate thickness direction (i.e., between the pressure surface 61 and the back surface 62). This pressure difference generates an air flow (vortex) that moves over the fins 151 from the high-pressure side to the low-pressure side. This flow causes high-temperature air near the base of the fins 151 to flow toward the outer periphery. At this time, the high-temperature air exchanges heat with the low-temperature outside air on the outer periphery. The air, which has been cooled by the heat exchange, then moves over the fins 151 and reaches the base of the fins 151 (i.e., the surface of the housing 34). The low-temperature air that comes into contact with the surface of the housing 34 again absorbs heat from the housing 34. This phenomenon occurs continuously throughout the entire circumferential direction. As a result, the cooling effect of the fins 151 on the electric motor 21 can be further enhanced.

[0036] The second embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the spirit and scope of the present disclosure.

[0037] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Figures 7 to 9. Note that the same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0038] In the electric fan 220 according to this embodiment, the fins 251 have a different shape, and an internal cooling passage 90 is formed inside the electric motor 21 and the inner duct 22. As shown in Fig. 7, in the electric fan 220, an annular gap that expands in the radial direction is formed between the upstream edge of the housing 34 of the electric motor 21 and the blades 42. This gap serves as an air intake port 91. Furthermore, an exhaust port 92 for discharging air to the outside is formed at the downstream end of the inner duct 22.

[0039] Some of the air compressed by the blades 42 flows into the housing 34 of the electric motor 21 through the intake 91. The air that flows into the housing 34 flows downstream mainly through the gap between the rotor core 32 and the stator core 33. At this time, heat from the electric motor 21 is transferred to the air. In other words, the electric motor 21 is cooled. The air then flows through the inner duct 22 and is discharged to the outside through the exhaust port 92. An internal cooling flow path 90 is formed by the flow path through which the air flows from the intake 91 to the exhaust port 92 as described above.

[0040] 8, the fins 251 extend from the rear side to the front side in the rotation direction of the blades 42 as they move from one side (upstream side) to the other side (downstream side) in the direction of the axis O. In other words, when viewed in the radial direction, the fins 251 are inclined with respect to the direction of the axis O. Furthermore, the fins 251 extend linearly in this inclined direction. In other words, the angle that the fins 251 form with respect to the axis O is constant throughout the entire extension length of the fins 251.

[0041] (Action and effect) According to the above configuration, the fins 251 are inclined with respect to the rotation direction of the blades 42 and the direction of the axis O, and therefore the air flow (arrow A in FIG. 8) that passes through the flow passages between the fins 251 includes a circumferential component (arrow Vt in FIG. 8). In other words, the air flow flows downstream while swirling in a spiral shape around the axis O.

[0042] As described above, the diameter of the outer peripheral surface of the inner duct 22 decreases toward the other side (downstream side) in the direction of the axis O. Therefore, as shown in the graph in FIG. 9 , the circumferential component of the velocity of the air flowing along the outer peripheral surface of the inner duct 22 gradually increases toward the other side (downstream side) in the direction of the axis O based on the law of conservation of angular momentum. As a result, as also shown in the graph in FIG. 9 , the dynamic pressure increases and the static pressure decreases around the exhaust port 92. In other words, the static pressure around the exhaust port 92 is lower than the static pressure around the intake port 91. This allows a smooth flow of air from the intake port 91 through the interior of the electric motor 21 (internal cooling flow path 90) toward the exhaust port 92. As a result, it is possible to achieve the cooling effect of the internal cooling flow path 90 in addition to the cooling effect of the fins 251. Therefore, it is possible to cool the electric motor 21 more efficiently.

[0043] The third embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0044] <Modifications common to all embodiments> Next, modified examples common to each embodiment will be described with reference to FIGS. 10 to 13. FIG.

[0045] In the above-described embodiments, examples have been described in which the fins 51 of the cooling member 25 are arranged at equal intervals in the circumferential direction. However, as shown in Fig. 10, it is possible to employ a configuration in which the intervals between the fins 51 in a certain region in the circumferential direction are narrower than in other regions. More specifically, in the example of Fig. 10, the intervals between the fins 51 are narrower in the region in the circumferential direction of the electric fan 20 that contacts the airframe 10 (wings 12).

[0046] Here, the flow velocity of the air taken in by the electric fan 20 tends to be particularly low in a portion of the circumferential direction that contacts the airframe 10 because it is obstructed by the airframe 10. With the above configuration, the spacing between the fins 51 is narrow in this region of low flow velocity. This makes it possible to supplement the cooling performance with a large number of fins 51 even in the region of low flow velocity. As a result, it is possible to eliminate uneven cooling performance in the circumferential direction.

[0047] Furthermore, in each of the above embodiments, the fins 51 have been described as having a rectangular cross-sectional shape when viewed from the direction of the axis O. That is, examples have been described in which a flat outer end surface 63 is formed on the radially outer side of the fin 51. However, as shown in FIG. 11 , the outer end surface 263 may have an arc shape that is convex radially outward. With this configuration, as described in the second embodiment, the vortex formed at the outer end surface 263 of the fin 51 can be further grown. This can further enhance the cooling effect of the fin 51.

[0048] Furthermore, the cross-sectional shape of the fins 51 is not limited to the above, and may be the shapes shown in Fig. 12 or 13. In the example of Fig. 12, the fins 51 have an isosceles trapezoidal cross-sectional shape. In the example of Fig. 13, the fins 51 have an isosceles triangular cross-sectional shape. Alternatively, although not shown, the fins 51 may have a scalene triangular cross-sectional shape.

[0049] <Additional Notes> The electric fan 20 and the electric aircraft 1 described in each embodiment can be understood, for example, as follows.

[0050] (1) The electric fan 20 of the first aspect comprises an electric motor 21 having an output shaft 31 extending along an axis O and a cylindrical housing 34 centered on the axis O, an inner duct 22 provided downstream of the electric motor 21, a plurality of blades 42 attached to the output shaft 31, and a cooling member 25 having a plurality of fins 51 provided on the outer peripheral surface of the housing 34.

[0051] According to the above configuration, heat from the electric motor 21 is dissipated to the outside via the fins 51 of the cooling member 25. This allows the electric motor 21 to be cooled efficiently.

[0052] (2) The electric fan 20 according to the second aspect is the electric fan 20 of (1), wherein the plurality of fins 51 protrude radially outward relative to the axis O, extend in the direction of the axis O, and are arranged at intervals in the circumferential direction.

[0053] According to the above configuration, since the fins 51 extend in the direction of the axis O, the flow of the air compressed and sent by the blades 42 is rectified in the direction of the axis O. This allows the electric motor 21 to be cooled while further increasing the thrust force of the electric fan 20.

[0054] (3) The electric fan 20 according to the third aspect is the electric fan 20 of (1), wherein the ends of the fins 51 on one side in the direction of the axis O extend toward the upstream side in the flow direction of the air compressed by the blades 42, and the ends of the fins 51 on the other side in the direction of the axis O extend in the direction of the axis O. When viewed radially, the fins 51 have an airfoil-shaped cross-sectional shape with the rear side in the direction of rotation of the blades 42 being the ventral surface 61 and the front side in the direction of rotation of the blades 42 being the dummy surface 62.

[0055] According to the above configuration, one end of each fin 51 in the direction of the axis O extends toward the upstream side of the flow direction of the air compressed by the blades 42, thereby reducing the possibility of the air flow separating from the surface of the fin 51. Furthermore, because the fins 51 have an airfoil-shaped cross section, the spacing between the fins 51 shrinks once and then expands again. This allows static pressure to be restored on the downstream side. This further reduces the possibility of separation occurring on the surface of the fin 51.

[0056] (4) The electric fan 20 according to a fourth aspect is the electric fan 20 of (1), wherein the inner duct 22 gradually reduces in diameter from one side in the direction of the axis O to the other side, the housing 34 is formed with an intake 91 through which the air compressed by the blades 42 is taken in toward the electric motor 21, the end of the inner duct 22 on the other side in the direction of the axis O is formed with an exhaust port 92 through which the air circulated through the intake 91 is discharged, and the fins 51 extend from the rear side to the front side in the direction of rotation of the blades 42 as they move from one side to the other side in the direction of the axis O.

[0057] According to the above configuration, since the fins 51 are inclined with respect to the rotation direction of the blades 42, the air passing through the fins 51 contains a circumferential component. Furthermore, since the inner duct 22 reduces in diameter toward the other side in the direction of the axis O, the circumferential component of the velocity of the air flowing along the outer circumferential surface of the inner duct 22 gradually increases toward the other side in the direction of the axis O. As a result, the static pressure around the exhaust port 92 becomes lower than the static pressure around the intake port 91. This makes it possible to form an air flow that flows from the intake port 91 through the inside of the electric motor 21 toward the exhaust port 92. As a result, the electric motor 21 can be cooled more efficiently.

[0058] (5) The electric fan 20 according to a fifth aspect is the electric fan 20 according to any one of (1) to (4), wherein the fins 51 have outer end faces 63 facing radially outward.

[0059] According to the above configuration, since the fins 51 have outer end surfaces 63 facing radially outward, a pressure difference occurs between both sides of the fins 51 in the plate thickness direction. This pressure difference generates an air flow (vortex) that passes over the fins 51 from the high-pressure side to the low-pressure side. This flow causes heat exchange between the high-temperature air near the base of the fins 51 and the low-temperature outside air on the outer periphery. As a result, the cooling effect of the fins 51 can be further enhanced.

[0060] (6) The electric fan 20 according to a sixth aspect is the electric fan 20 according to (5), wherein the outer end surface 63 has an arc shape that is convex radially outward.

[0061] According to the above configuration, it is possible to further grow the vortex formed at the outer end surface 63 of the fin 51. This makes it possible to further enhance the cooling effect of the fin 51.

[0062] (7) An electric aircraft 1 according to a seventh aspect includes the electric fan 20 of (1) and an airframe 10 to which the electric fan 20 is attached.

[0063] According to the above configuration, the electric fan 20 has high cooling performance, which makes it possible to extend the flight range and life cycle of the electric aircraft 1.

[0064] (8) The electric aircraft 1 according to the eighth aspect is the electric aircraft 1 of (7), in which in some circumferential regions of the electric fan 20 that contact the fuselage 10, the spacing between the fins 51 is narrower than in other regions.

[0065] The flow velocity of the air taken in by the electric fan 20 tends to be particularly low in a portion of the circumferential direction that contacts the fuselage 10. With the above-described configuration, the spacing between the fins 51 is narrow in this region where the flow velocity is low, thereby eliminating uneven cooling performance in the circumferential direction. [Explanation of symbols]

[0066] 1…Electric aircraft 10...Aircraft 11...Aircraft body 12...Wings 20...Electric fan 21...Electric motor 22...Inner duct 23...Outer duct 24...Propeller 25...Cooling element 26...Strut 31...Output shaft 32...Rotor core 33... Stator core 34…Housing 35...Bearing device 41...Spinner 42...Blade 51...Finn 61...ventral surface 62...Back 63…Outer end face 80...Air flow path 90...Internal cooling channel 91...Intake port 92...Exhaust port 151...Finn 220...Electric fan 251...Finn 263…Outer end face O…Axis line

Claims

1. an electric motor including an output shaft extending along an axis, a rotor core attached to an outer peripheral surface of the output shaft, a stator core covering the rotor core from the outer peripheral side, and a cylindrical housing centered on the axis, with the stator core fitted into an inner peripheral surface thereof; a plurality of blades attached to one side of the output shaft in the axial direction; an inner duct having an outer circumferential surface extending from the outer circumferential surface of the housing to the other side in the axial direction, the inner duct gradually decreasing in diameter from the one side to the other side in the axial direction; a cooling member having a plurality of fins provided on an outer peripheral surface of the housing; Equipped with an intake port is formed on one side of the housing in the axial direction, through which air compressed by the blades is taken toward the rotor core and the stator core inside the housing; and an exhaust port is formed on the other end of the inner duct in the axial direction, through which air circulated through the intake port is discharged; The fins extend from the rear side to the front side in the rotation direction of the blades as they move from one side to the other side in the axial direction.

2. 2. The electric fan according to claim 1, wherein the plurality of fins protrude radially outward relative to the axis, extend in the axial direction, and are arranged at intervals in the circumferential direction.

3. 2. The electric fan according to claim 1, wherein an end of each fin on one side in the axial direction extends toward an upstream side in the flow direction of the air compressed by the blades, and an end of each fin on the other side in the axial direction extends in the axial direction, and the fin has an airfoil-shaped cross-section, as viewed radially, with a pressure surface on the rear side in the direction of rotation of the blades and a back surface on the front side in the direction of rotation of the blades.

4. The electric fan according to claim 1 , wherein the fins have outer end surfaces facing radially outward.

5. 5. The electric fan according to claim 4, wherein the outer end surface has an arc shape that is convex radially outward.

6. An electric fan according to any one of claims 1 to 5; an aircraft to which the electric fan is attached; An electric aircraft comprising:

7. The electric aircraft according to claim 6 , wherein the distance between the fins is narrower in a circumferential region of the electric fan that contacts the airframe than in other regions.

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