Unmanned vehicle

Abstract

An unmanned vehicle (1) comprises: a motor (5) that has a frame (7), a stator (8) accommodated in the frame (7), and a rotor (9); and an attachment (4) that has a substrate (44), an electronic component (45) provided on the substrate (44), a heat sink (43) facing the electronic component (45), and a case (42) covering the heat sink (43). The heat sink (43) is disposed on the case (42) side with respect to the substrate (44). A fluid is discharged toward the motor (5) from an opening (42a) of the case (42) facing the frame (7). The discharged fluid is drawn toward an opening (75) of the frame (7) facing the case (42). The drawn fluid is discharged toward the case (42) through a gap between the rotor (9) and the stator (8).

Description

Drone 【0001】 The present invention relates to a drone. 【0002】 For example, Patent Document 1 discloses a propulsion device for an aircraft. This propulsion device has a motor that rotates a propeller and an inverter for the motor. 【0003】 Japanese Unexamined Patent Application Publication No. 2024-004442 【0004】 A plurality of heat dissipation fins are provided on the housings of the motor and the inverter. In suppressing heat generation of the motor and the inverter, it is required to further enhance heat dissipation. 【0005】 Therefore, one of the problems of the present invention is to provide a drone that can further enhance heat dissipation. 【0006】 The drone according to one aspect of the present invention includes a frame, a stator housed in the frame, a motor having a rotor, a substrate, electronic components provided on the substrate, a heat sink facing the electronic components, and an attachment having a case that covers the heat sink. The heat sink is disposed on the case side with respect to the substrate, fluid is discharged from an opening of the case facing the frame toward the motor, the discharged fluid is sucked toward an opening of the frame facing the case, and the sucked fluid is discharged toward the case through a gap between the rotor and the stator. 【0007】 It is a perspective view schematically showing a part of the structure of a drone 1 according to an embodiment of the present invention. It is a partially enlarged perspective view schematically showing a part of the structure of a drone 1 according to an embodiment of the present invention. It is a perspective cross-sectional view taken along line 3-3 of FIG. 2. It is a cross-sectional view taken along line 4-4 of FIG. 2. It is an exploded perspective cross-sectional view taken along line 5-5 of FIG. 2. It is a perspective view of the state where the motor 5 is removed from the attachment 4. It is a cross-sectional view taken along line 7-7 of FIG. 4. It is an exploded perspective view schematically showing the structure of a propulsion device 3A according to a modified example. It is a cross-sectional view taken along line 9-9 of FIG. 8. 【0008】Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic perspective view showing a part of the structure of an unmanned aircraft 1 according to an embodiment of the present invention. The unmanned aircraft 1 is a so-called multicopter having a plurality of propulsion devices 3 attached to the tip of an arm 2. In the following description of the embodiment of the unmanned aircraft 1, the terms "up" and "down" will be used for convenience, but the terms "up" and "down" do not necessarily coincide with up and down in the direction of gravity, and are defined as up and down for convenience when viewed in relation to each propulsion device 3. 【0009】 The unmanned aerial vehicle 1 comprises a main body B, a plurality of arms 2, and a plurality of propulsion devices 3. The main body B is positioned, for example, at the center of the unmanned aerial vehicle 1. Each arm 2 extends from the main body B in a predetermined direction. Each propulsion device 3 is attached, for example, to the tip of each arm 2. Note that in Figure 1, only the tip portion of one of the plurality of arms 2 is shown. In this example, a cylindrical arm 2 is described as an example, but the arms 2 may have various other shapes. 【0010】 The main body B of the unmanned aircraft 1 incorporates components such as a control device for driving the unmanned aircraft 1, a battery, various sensors, and cameras. Multiple arms 2 extend radially from this main body B. The arms 2 are formed from, for example, cylindrical metal or resin materials. Wiring housed in the internal space of the arms 2 connects the battery and other components incorporated in the main body B to the propulsion device 3. In this way, power is supplied from the battery in the main body B to the propulsion device 3. 【0011】 The propulsion system 3 comprises an attachment 4, a motor 5, and a propeller 6. The attachment 4 is attached to the end of the arm 2 by housing a portion of the attachment 4 within the arm 2. For attachment, fixing members (not shown), such as screws, are used. The motor 5 is fixed to the upper surface of the attachment 4. The propeller 6 is attached to the rotor of the motor 5. In this way, the propeller 6 is rotatable around the axis of rotation x. In this example, the attachment 4 and the motor 5 have a generally cylindrical outer shape with the axis of rotation x as the central axis. 【0012】The propeller 6 is attached to the rotor of the motor 5 via a fixing member (not shown), such as a screw. In this example, the propeller 6 consists of two blades 61, 61 that extend in opposite directions to each other in a direction perpendicular to the rotation axis x. The two blades 61, 61 have the same shape as each other. Note that propellers with other numbers of blades may also be used for the propeller 6. As the propeller 6 rotates around the rotation axis x, the propulsion device 3 can generate lift and thrust for the unmanned aircraft 1. 【0013】 Figure 2 is a partially enlarged perspective view schematically showing the structure of a part of the unmanned aircraft 1 according to one embodiment of the present invention. Figure 3 is a perspective cross-sectional view along line 3-3 in Figure 2. Referring together to Figures 2 and 3, the attachment 4 has a housing 41 positioned on the lower side in the direction along the rotation axis x (hereinafter referred to as the "rotation axis direction"), a case 42 positioned on the upper side in the rotation axis direction, a heat sink 43 sandwiched between the housing 41 and the case 42, and a substrate 44 positioned along the lower surface of the heat sink 43. The case 42 covers the housing 41 from above. An internal space S1 of the attachment 4 is formed between the housing 41 and the case 42. In this example, the housing 41 and the case 42 are formed by integral molding from, for example, a resin material. 【0014】 As shown in Figure 3, the heat sink 43 has a cylinder 43a inserted into the arm 2, a heat sink body 43b (hereinafter referred to as "heat sink body") 43b integrated with the cylinder 43a, and one or more fins 43c extending upward from the heat sink body 43b. The cylinder 43a extends cylindrically in the radial direction perpendicular to the axis of rotation x. The cylinder 43a is fixed to the arm 2 by a fixing member (not shown), such as a screw. The heat sink body 43b extends from the inner end of the cylinder 43a (the end on the heat sink 43 side) to the outside (towards the body B of the unmanned aircraft 1). The cylinder 43a, the heat sink body 43b, and the fins 43c are integrally formed from a metal material with high thermal conductivity, such as aluminum. 【0015】The inner and outer ends of the cylinder 43a are open. In this example, the opening at the outer end of the cylinder 43a (the end on the main body B side of the unmanned aircraft 1) forms an air intake 43d for a fluid (e.g., a gas such as air; air will be used as an example below). For example, a fan motor (not shown) may be placed inside the arm 2. The rotation of the fan of this fan motor generates an airflow, for example, from the main body B side through the arm 2 toward the internal space S1 of the attachment 4. The fan motor may also be mounted at other locations on the unmanned aircraft 1, such as the underside of the main body B. Furthermore, if an airflow is generated inside the motor 5 by the rotation of a rotor, which will be described later, for example, due to negative pressure, the incorporation of the fan motor may be omitted. 【0016】 The internal space S1 between the housing 41 and the case 42 houses the heat sink body 43b and the substrate 44 of the heat sink 43. The housing 41 and the case 42 are fixed to the heat sink 43 by being joined to each other by fixing members (not shown), such as screws. In this way, the housing 41 and the case 42 are fixed to the arm 2. The heat sink 43 is positioned on the case 42 side relative to the substrate 44. The substrate 44 is fixed to the heat sink 43 via fixing members (not shown), such as screws. Note that instead of forming the case 42 from a resin material, the case 42 and the heat sink 43 may be integrally formed from a metal material with high thermal conductivity, such as aluminum. 【0017】 The motor 5 includes a frame 7, a stator 8 housed in the frame 7, and a rotor 9 rotatably supported on the frame 7 around a rotation axis x. The frame 7 is positioned on the case 42 of the attachment 4. The frame 7 is fixed to the case 42 of the attachment 4 via fixing members (not shown), such as screws. The rotor 9 is rotatably supported on the frame 7 by two bearings 10, 10 arranged in the direction of the rotation axis, for example. The bearings 10 are, for example, ball bearings. The propeller 6 is fixed to the rotor 9 via fixing members (not shown), such as screws. In this way, the propeller 6 rotates together with the rotor 9 around the rotation axis x. 【0018】Figure 4 is a cross-sectional view along line 4-4 in Figure 2. Figure 5 is an exploded perspective cross-sectional view along line 5-5 in Figure 2. The cross-sections in Figures 4 and 5 are the same as those in Figure 3. Note that the arm 3 is not shown in Figures 4 and 5, and the propeller 6 is not shown in Figure 5. Referring to Figures 4 and 5 together, the attachment 4 in this example has one or more electronic components 45 provided on the upper surface of the circuit board 44. The circuit board 44 on which the electronic components 45 are mounted constitutes a so-called ESC (Electronic Speed ​​Controller). The circuit board 44 is placed between the battery and the motor 5 of the main body B of the unmanned aircraft 1, and can control the rotational speed of the motor 5, i.e., the propeller 6, by controlling the voltage applied to the motor 5. 【0019】 In the direction of rotation, the lower surface of the heat sink body 43b faces the upper surface of the electronic component 45 on the substrate 44. A sheet-like thermally conductive material (hereinafter referred to as "thermal conductive material") 46 (not shown in Figure 5) having high thermal conductivity is sandwiched between the electronic component 45 and the heat sink body 43b. The case 42 covers the heat sink body 43b and the fins 43c. In this example, a part of the heat sink body 43b and the upper ends of several fins 43c are in contact with the inner surface of the case 42. When the propulsion device 3 is in operation, current is supplied to the electronic component 45, causing the electronic component 45 to generate heat. This heat is transferred to the heat sink body 43b and the fins 43c. The heat is then released into the atmosphere from the heat sink body 43b and the fins 43c. 【0020】 Figure 6 is a perspective view of the propulsion device 3 with the motor 5 removed from the attachment 4. Figure 6 shows the top surface of the attachment 4 and the bottom surface of the motor 5. Note that the arm 2 and propeller 6 are not shown in Figure 6. Referring to Figures 4 to 6 together, one or more openings 42a are formed on the top surface of the case 42, penetrating the case 42 along the axis of rotation. In this example, four openings 42a are arranged in the circumferential direction around the axis of rotation x. Each opening 42a is formed, for example, in a fan shape in a plan view along the axis of rotation. The internal space S1 of the attachment 4 is connected to the external space of the attachment 4 through these four openings 42a. 【0021】 On the outer periphery of the four openings 42a, a portion 42b (hereinafter referred to as the "first annular portion") is formed that protrudes upward in an annular shape from the upper surface of the case 42. That is, the four openings 42a are surrounded by the first annular portion 42b. Within the first annular portion 42b, a single recess 42c is formed that is recessed downward from the upper surface of the case 42, outside the four openings 42a. In this example, in a plan view in the direction of rotation axis, the inner circumferential surface of the recess 42c has a contour that includes, for example, a circular portion and four protrusions that project radially from the circular portion. One or more through holes 42d are formed in the recess 42c into which a fixing member (not shown), such as a screw, is inserted. 【0022】 On the other hand, the frame 7 of the motor 5 has a base 71 that extends radially in a disc shape, a protrusion 72 that projects downward from the lower surface of the base 71, and a portion (hereinafter referred to as the "second annular portion") 73 that similarly projects downward in an annular shape from the lower surface. In a plan view in the direction of rotation axis, the inner circumferential surface of the protrusion 72 of the base 71 has a contour corresponding to the recess 42c of the case 42. One or more through holes 74 are formed in the protrusion 72 into which fixing members (not shown), such as screws, are inserted. The positions of the through holes 74 are formed at positions corresponding to the through holes 42d of the case 42. The frame 7 is formed, for example, by integral molding from a resin material. 【0023】 The base 71 has one or more (three in this example) openings 75 that penetrate the base 71 along the axis of rotation, adjacent to the protrusion 72. Each opening 75 is formed in a curved shape (sector shape) in a plan view along the axis of rotation. The internal space S2 formed inside the motor 5 is connected to the space outside the motor 5 through these three openings 75. The base 71 also has an opening 76 for passing wiring (not shown). The second annular portion 73 is positioned radially offset to the outer circumference of the first annular portion 42b of the case 42. That is, the radial dimension of the inner surface of the second annular portion 73 is set to be larger than the radial dimension of the outer surface of the first annular portion 42b. 【0024】When the motor 5 is positioned on the case 42 from above in the direction of rotation, the protrusion 72 of the frame 7 is positioned within the recess 42c of the case 42. In this way, the frame 7, i.e., the motor 5, is positioned relative to the case 2. The through hole 74 formed in the protrusion 72 communicates with the through hole 42d formed in the recess 42c. The motor 5 is fixed to the case 42, i.e., the attachment 4, by fixing members such as screws inserted into the through holes 74 and 42d. At this time, as shown in Figure 4, the inner circumferential surface of the second annular portion 73 of the frame 7 partially faces the outer circumferential surface of the first annular portion 42b of the case 42. Also, in the direction of rotation, the opening 75 of the frame 7 faces the opening 42a of the case 42. 【0025】 On the other hand, the upper surface of the base 71 has a first wall 77 that rises upright in an annular shape from the upper surface on the inner circumference side, and a second wall 78 that rises upright in an annular shape from the upper surface on the outer circumference side of the first wall 77. The outer rings of the bearings 10, 10 are held on the inner circumference surface of the first wall 77. The outer rings of the bearings 10 are fitted onto the inner circumference surface of the first wall 77 and fixed, for example, with adhesive. A flat cylindrical pusher 11 is attached to the lower end of the first wall 77. In this example, the pusher 11 can apply a predetermined preload to the outer ring of the lower bearing 10 in the direction of rotation. 【0026】 Figure 7 is a cross-sectional view along the line 7-7 in Figure 4. Referring together to Figures 4, 5, and 7, the outer circumferential surface of the first wall 77 is spaced radially apart from the inner circumferential surface of the second wall 78 at a predetermined interval. In this way, an annular space is formed between the outer circumferential surface of the first wall 77 and the inner circumferential surface of the second wall 78. This space forms part of the internal space S2 of the motor 5 and communicates with the space outside the motor 5 through the opening 75 of the base 71. A stator 8 is fixed to the outer circumferential surface of the second wall 78. The stator 8 has a stator core 81, a plurality of coils 82, and a plurality of insulators (not shown). 【0027】The stator core 81 is formed from, for example, a laminate of magnetic material and functions as a yoke for the stator 8. The stator core 81 has an annular portion (hereinafter referred to as the "annular portion") 83 fixed to the outer circumferential surface of the second wall 78, and a plurality of teeth 84 extending radially outward from the annular portion 83. A coil 82 is wound around each tooth 84. An insulator made of insulating material is placed between the teeth 84 and the coil 82. In this way, electrical insulation is established between the stator core 81 and the coil 82. A magnetic pole portion 85 is formed at the outer circumferential end of each tooth 84 of the stator core 81. 【0028】 On the other hand, the rotor 9 has a shaft 91, a cover 92, a yoke 93, and a magnet 94. The shaft 91 is supported by two bearings 10, 10. The shaft 91 is formed, for example, in a cylindrical shape. The cover 92 is fixed to the upper end of the shaft 91. The cover 92 has a body 92a, a projection 92b, and an impeller 92c. The body 92a is formed in a disc shape that extends from the shaft 91 to the outer circumference of the stator 8. No openings are formed in the body 92a. That is, the body 92a closes the upper surface of the internal space S2 of the motor 5. The projection 92b protrudes upward from the upper surface of the body 92a around the shaft 91. 【0029】 The impeller 92c is formed on the lower surface of the main body 92a. The impeller 92c has a plurality of blades 92d arranged at predetermined intervals (for example, equally spaced) in the circumferential direction. In this example, 12 blades 92d are formed. The impeller 92c is positioned in the space between the outer circumferential surface of the first wall 77 and the inner circumferential surface of the second wall 78. That is, the impeller 92c is positioned inside the stator 8. Each blade 92d is formed in a flat plate shape along a virtual plane containing the rotation axis x. For example, it extends in the radial direction. The dimensions, shape, thickness, number, etc. of each blade 92d may be appropriately set according to the size and heat generation of the motor 5. The cover 92 is formed, for example, by integral molding from a resin material. 【0030】A generally cylindrical yoke 93 is attached to the outer end of the main body 92a. A cylindrical magnet 94 is attached to the inner surface of the yoke 93. The yoke 93 is made of, for example, a magnetic material. The magnet 94 is, for example, a permanent magnet. The magnet 94 may be a single cylindrical permanent magnet. The inner surface of the magnet 94 faces the magnetic pole portion 85 of the stator core 81. A predetermined magnetic gap is formed radially between the inner surface of the magnet 94 and the magnetic pole portion 85. When current is supplied to the coil 82, a magnetic interaction is generated between the coil 82 and the magnet 94. This magnetic interaction allows the rotor 9 to rotate around the rotation axis x. The motor 5 is a so-called outer rotor type motor. 【0031】 As shown in Figure 4, the yoke 93 has a first portion 93a for mounting the magnet 94, a second portion 93b facing the outer peripheral end of the base 71 of the frame 7 in the radial direction, and a third portion 93c facing the lower surface of the outer peripheral end of the base 71 in the rotation axis direction. The second portion 93b is positioned on the inner circumference side of the first portion 93a. In this example, the third portion 93c is connected to the lower end of the second portion 93b. Thus, an annular gap 12 is formed between the second portion 93b and the third portion 93c and the base 71. This gap 12 forms a so-called labyrinth structure. The internal space S2 and the space outside the motor 5 are in communication through the gap 12. 【0032】 In the propulsion device 3, the space within the arm 2 and the internal space S1 of the attachment 4 are in communication with each other via the intake port 43d of the cylinder 43a, creating a space through which fluid can move. Furthermore, the internal space S1 of the attachment 4 and the internal space S2 of the motor 5 are in communication with each other via the opening 42a of the case 42 and the opening 75 of the base 71, creating a space through which fluid can move. In addition, the internal space S2 of the motor 5 and the space outside the motor 5 are in communication with each other via the gap 12 between the yoke 93 and the base 71, allowing fluid to move to the outside. Wiring (not shown) for supplying current to, for example, the coil 82 is routed from the space within the arm 2 through the internal space S1, the opening 42a and the opening 76 to the internal space S2. 【0033】 In the propulsion device 3 described above, when current is supplied to the coil 82, the rotor 9, or propeller 6, rotates around the axis of rotation x. At this time, heat is generated in the coil 82 and the electronic components 45 on the circuit board 44. For example, air generated by the fan motor located inside the arm 2 is discharged from inside the arm 2 through the intake port 43d and through the inside of the cylinder 43a toward the internal space S1 of the attachment 4. The air flows into the internal space S1 of the attachment 4 and becomes charged with heat transferred from the electronic components 45 to the heat sink 43. After that, the air is discharged from the opening 42a of the case 42 toward the motor 5. The discharged air is drawn toward the opening 75 of the base 71 of the frame 7. 【0034】 Subsequently, in the motor 5, the air drawn into the internal space S2 through the opening 75 of the base 71 is agitated by the rotation of the impeller 92c, i.e., the multiple blades 92d, and flows into the gap between the stator 8 and the rotor 9 in the radial direction, and into the gaps between the coils 82, 82. At this time, the air in the internal space S2 of the motor 5 becomes heated by the coils 82. Subsequently, the heated air generated by the electronic components 45 and coils 82 is discharged into the space outside the motor 5 towards the case 42 through the gap 12 between the yoke 93 and the base 71. In this way, the propulsion device 3 can efficiently cool the electronic components 45 and coils 82. In the unmanned aircraft 1, heat dissipation can be further improved. 【0035】 Figure 8 is an exploded perspective view schematically showing the structure of a modified propulsion device 3A. Figure 9 is a cross-sectional view along the line 9-9 in Figure 8. Referring to both Figures 8 and 9, in this propulsion device 3A, a motor 5A is fixed to the attachment 4 of the aforementioned propulsion device 3 in place of the motor 5. This motor 5A has one or more fins 79 formed on the lower surface of the base 71 on the outer circumference side of the openings 75 and 76. In this example, 24 fins 79 are arranged circumferentially on the lower surface of the base 71. The fins 79 are formed in a flat plate shape along, for example, a virtual plane containing the axis of rotation x. Note that the formation of the second annular portion 73 on the lower surface of the base 71 is omitted. 【0036】In particular, as shown in Figure 9, in the axial direction, the height of the protrusion 72 from the lower surface of the base 71 is set to be greater than the height of the fin 79 from the lower surface of the base 71. When this motor 5A is placed on the case 42, in the rotation axis direction, each fin 79 is positioned to face, at least partially, the opening 42a of the case 42. At this time, the lower end of the fin 79 may be in contact with the upper end of the first annular portion 42b of the case 42. Alternatively, in the radial direction, the outer peripheral end of the fin 79 may face the inner peripheral surface of the first annular portion 42b. That is, in the radial direction, the dimension of the outer peripheral end of the fin 79 may be smaller than the dimension of the inner peripheral surface of the first annular portion 42b. 【0037】 As shown in Figure 9, the impeller 92c is omitted in the cover 92, but as described above, the impeller 92c may be formed. On the other hand, a mesh-like member 14 may be placed along the upper surface of the base 71 to close the opening 75 of the base 71. This member 14 is formed, for example, in the form of a sheet with a plurality of fine holes. This member 14 can suppress the inflow of dust and other particles from the opening 75 of the base 71 into the internal space S2 of the motor 5. Other components similar to those of the propulsion device 3 described above are given the same reference numerals, and redundant explanations are omitted here. 【0038】 In this propulsion system 3A, the heat generated in the coil 82 is conducted to the base 71 of the frame 7 via the stator core 81 and the second wall 78 of the base 7. This heat is released into the atmosphere through fins 79 formed on the lower surface of the base 71. When the propulsion system 3A is in operation, similar to the propulsion system 3 described above, the air discharged from the opening 42a of the case 42 toward the motor 5 is drawn toward the opening 75 of the base 71 of the frame 7. At this time, the air becomes charged with the heat released into the atmosphere from the fins 79. Subsequently, the air is discharged from the internal space S2 of the motor 5 through the gap 12 to the space outside the motor 5, as described above. In this way, the propulsion system 3 can efficiently cool the electronic components 45 and the coil 82. The unmanned aircraft 1 can further improve heat dissipation. 【0039】Although the present invention has been described above through the embodiments described above, the technical scope of the present invention is not limited to the scope described in the embodiments above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the embodiments described above. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention. 【0040】 The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit its interpretation. Furthermore, the embodiments described above do not limit the scope of application of the present invention, and the present invention may encompass anything as its target application. The components of the above embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be modified as appropriate. 【0041】 For example, the present invention includes differences that arise in the implementation of manufacturing tolerances, etc. Furthermore, components shown in different embodiments can be partially substituted or combined to the extent that they do not conflict with the technical requirements. In addition, each component can be selectively combined as appropriate to achieve at least some of the above-mentioned problems and effects. 【0042】1 Unmanned aircraft, 2 Arm, 3, 3A Propulsion device, 4 Attachment, 41 Housing, 42 Case, 43 Heat sink, 42a Opening, 42b Annular projection (first annular section), 42c Recess, 43a Cylinder, 43b Heat sink body, 43c Fin, 43d Air intake, 44 Substrate, 45 Electronic component, 46 Thermally conductive material (thermal conductive material), 5, 5A Motor, 6 Propeller, 61 Blade, 7 Frame, 71 Base, 72 Protrusion, 73 Annular projection (second annular section), 74 Through hole, 75 Opening, 76 Opening, 77 First wall, 78 Second wall, 79 Fin, 8 Stator, 81 Stator core, 82 Coil, 83 Annular section (annular section), 84 Teeth, 85 Magnetic pole section, 9 Rotor, 91 Shaft, 92 Cover, 92a Main body, 92b Protruding part, 92c Impeller, 92d Blade, 93 Yoke, 93a First part, 93b Second part, 93c Third part, 94 Magnet, 10 Bearing, 11 Pusher, 12 Gap, 14 Mesh-like member, B Main body, S1 Internal space, S2 Internal space, x Rotation axis

Claims

1. An unmanned aircraft comprising: a motor having a frame, a stator housed in the frame, and a rotor; an attachment having a substrate, an electronic component provided on the substrate, a heat sink facing the electronic component, and a case covering the heat sink, wherein the heat sink is positioned on the case side relative to the substrate, air is discharged toward the motor from an opening in the case facing the frame, the discharged fluid is drawn toward the opening in the frame facing the case, and the drawn fluid is discharged toward the case through the gap between the rotor and the stator.

2. The unmanned machine according to claim 1, wherein the attachment comprises a housing covered by the case, the heat sink comprises a radially extending cylinder, and the fluid passing through the inside of the cylinder is discharged toward the motor.

3. The unmanned aircraft according to claim 1 or 2, wherein the rotor comprises an impeller positioned inside the stator in the radial direction.

4. The unmanned aircraft according to any one of claims 1 to 3, wherein a fluid suction port is formed in the cylinder.

5. The unmanned aircraft according to any one of claims 1 to 4, wherein the frame is positioned in the case in the direction of rotation axis.

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