Motor and unmanned machine

Abstract

The present invention is provided with a stator (46), a rotor (51), and a cover (52) fixed to the rotor (51). The cover (52) is provided with one or more fins (56), and the stator (46) is disposed between the rotor (51) and the fins (56) in the rotational axis direction.

Description

Motors and drones

[0001] The present invention relates to a motor and an unmanned aerial vehicle.

[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] JP 2024-4442 A

[0004] The housings of the motor and inverter are provided with multiple heat dissipation fins, and it is important to further improve heat dissipation in order to suppress heat generation from the motor and inverter.

[0005] Therefore, one of the objects of the present invention is to provide a motor and an unmanned aircraft that can further improve heat dissipation.

[0006] A motor according to one aspect of the present invention comprises a stator, a rotor, and a cover fixed to the rotor, the cover having one or more fins, and the stator being arranged between the rotor and the fins in the direction of the rotation axis.

[0007] An unmanned aircraft according to one embodiment of the present invention comprises the motor described above, a base having an opening connected to the outside, and an attachment supporting the base, and a gap is formed between the cover and the base in the radial direction, and the space inside the cover is connected to the outside via the gap and the opening in the cover.

[0008] 2 is a perspective view schematically illustrating the structure of an unmanned aerial vehicle 1 according to one embodiment of the present invention. A cross-sectional view taken along line 2-2 in FIG. 1. A cross-sectional view taken along line 3-3 in FIG. 2. A cross-sectional perspective view taken along line 4-4 in FIG. 2. A cross-sectional perspective view taken along line 5-5 in FIG. 2. A cross-sectional view taken along line 6-6 in FIG. 2. A cross-sectional perspective view taken along line 7-7 in FIG. 2. A cross-sectional perspective view taken along line 8-8 in FIG. 2. A cross-sectional view of the unmanned aerial vehicle 1 corresponding to FIG. 2 and showing the air flow.

[0009] An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view schematically illustrating the structure of an unmanned aircraft 1 according to an embodiment of the present invention. The unmanned aircraft 1 is a so-called multicopter equipped with multiple propulsion devices. The unmanned aircraft 1 includes a main body (not shown), multiple rods 2 extending in a predetermined direction from the main body, attachments 3 disposed at the tip of each rod 2, motors 4 attached to the attachments 3, and propellers (not shown) attached to the motors 4. The motors 4 and propellers constitute the propulsion devices of the unmanned aircraft 1. Note that FIG. 1 shows only the tip portion of one of the multiple rods 2. Note that in the following description, the terms "upper" and "lower" do not necessarily correspond to the upper and lower positions in the direction of gravity.

[0010] The drone 1's main body incorporates components such as a control device for controlling the drone's operation, a battery, various sensors, and a camera. A plurality of rods 2 extend, for example, radially from the main body. In this example, the rods 2 are cylindrical and centered on a central axis x1, and are formed from, for example, a metal or resin material. The tips of the rods 2 are open. Wires 5 are housed in the internal space S1 inside the rods 2. The wires 5 connect a battery or other component built into the main body to the motor 4. The rods 2 may have shapes other than cylindrical. Furthermore, a single rod 2 does not need to extend directly from the main body; for example, a T-shaped rod with two tips, such as an H-shape, may be used. Although a single wire 5 is illustrated, multiple wires 5 may be housed in the internal space S1 of the rods 2.

[0011] An attachment 3 for mounting a motor 4 is connected to the tip of the rod 2. In this example, the attachment 3 is formed integrally with the tip of the rod 2. The attachment 3 is formed, for example, from a resin material or a metal material. A motor 4 is fixed onto the attachment 3. The motor 4 defines a rotation axis x2. The rotation axis x2 intersects with the central axis x1 of the rod 2. In this example, the rotation axis x2 is perpendicular to the central axis x1. A rotation shaft 41 of the motor 4, centered on the rotation axis x2, rotates around the rotation axis x2. A propeller is supported on the rotation shaft 41. In this way, the rotation of the propeller around the rotation axis x2 generates lift and thrust in the propulsion device.

[0012] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. Referring to both FIGS. 2 and 3, the attachment 3 includes an annular flange 31 disposed at the tip of the rod 2, a base (hereinafter referred to as the "support base") 32 extending from the upper end of the flange 31 along the central axis x1, and two portions (hereinafter referred to as "connecting arms") 33, 33 connecting the flange 31 and the support base 32 to each other. The flange 31 is formed around the outer circumferential surface of the rod 2. The upper surface of the support base 32 is defined, for example, along an imaginary plane perpendicular to the rotation axis x2. The connecting arms 33, 33 extend obliquely from the front surface of the flange 31 to the lower surface of the support base 32, intersecting the direction of the rotation axis x2 (hereinafter referred to as the "rotation axis direction").

[0013] A base 34 is supported on the upper surface of the support stand 32 of the attachment 3. The base 34 has a bottom plate 34a and a side wall 34b. The bottom plate 34a is formed, for example, in a disk shape. The side wall 34b is formed in a cylindrical shape rising upward from the outer peripheral edge of the bottom plate 34a. In this way, a cylindrical storage space S2 is defined within the base 34. The lower surface of the bottom plate 34a is supported on the upper surface of the support stand 32. The base 34 is formed, for example, from a metal material with high thermal conductivity, such as aluminum. A heat dissipation component, i.e., a heat sink 35, is provided on the base 34. The heat sink 35 is disposed within the storage space S2. The heat sink 35 has, for example, a flat, rectangular outer shape. The heat sink 35 is formed, for example, from a metal material with high thermal conductivity, such as aluminum.

[0014] 4 is a cross-sectional perspective view taken along line 4-4 in FIG. 2. Referring to FIGS. 2 to 4 together, the heat sink 35 has a base plate 35a and a block 35b extending downward from the lower surface of the base plate 35a. The base plate 35a and the block 35b are integrally formed. The base plate 35a is formed, for example, in the shape of a flat plate extending parallel to the bottom plate 34a of the base 34. The block 35b is formed, for example, in the shape of a flat rectangular parallelepiped. The lower surface of the block 35b is in contact with the upper surface of the bottom plate 34a of the base 34.

[0015] 3 and 4, the block 35b has a plurality of slits 35c formed therein, which extend from the underside of the block 35b to the base plate 35a. The slits 35c define a plurality of heat dissipation fins 35d in the block 35b. The heat dissipation fins 35d are arranged, for example, parallel to one another. The heat sink 35 is attached to the support base 32 of the attachment 3 with fixing members 36, such as four screws. The fixing members 36 are screwed into holes formed adjacent to the four corners of the block 35b.

[0016] 2 and 4 , an opening 34c is formed in the bottom plate 34a of the base 34. The opening 34c is connected to the outside of the base 34. That is, the opening 34c connects the storage space S2 inside the base 34 to the external space outside the base 34. In this example, the opening 34c in the base 34 faces the opening 2a formed across the rod 2, the flange 31, and the support base 32 in the rotation axis direction. That is, the internal space S1 of the rod 2 is connected to the opening 34c in the base 34. The opening 2a is formed at the tip of the rod 2. The opening 2a is connected to the internal space S1 inside the rod 2. In this way, the storage space S2 of the base 34 and the internal space S1 of the rod 2 are connected to each other through the openings 34c and 2a. In this example, the openings 34c and 2a both have rectangular contours in a plan view in the rotation axis direction.

[0017] A substrate 37 is disposed on the heat sink 35. One or more electronic components 37a are provided on the underside of the substrate 37. Specifically, the electronic components 37a are mounted on the underside of the substrate 37. FIG. 5 is a cross-sectional perspective view taken along line 5-5 in FIG. 2. Referring to FIGS. 2, 4, and 5, the electronic components 37a face the upper surface of the base plate 35a of the heat sink 35. In this example, six electronic components 37a are in contact with the upper surface of the base plate 35a. The heat sink 35 thus functions as a mount for the substrate 37. The wiring 5 is connected to the motor 4, for example, via the substrate 37. The substrate 37 constitutes an ESC (electric speed controller), and is disposed between the main body's battery and the motor 4. The ESC can control the rotational speed of the motor 4 by controlling the voltage applied to the motor 4.

[0018] FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 2. As shown in FIG. 6, the substrate 37 has a circular shape with a portion thereof cut out in an arched shape (recess) in a plan view in the rotation axis direction. For example, between the outer peripheral edge of the substrate 37 and the inner peripheral surface of the side wall 34b of the base 34, an arched gap V1 is formed by cutting out a relatively large portion of the outer periphery of the substrate 37, and a circular or trapezoidal gap V2 is formed by cutting out a relatively small portion of the outer periphery of the substrate 37 in a plan view in the rotation axis direction. In this example, the gap V1 overlaps the positions of the openings 2a and 34c in a plan view. The gaps V1 and V2 form a space for arranging the wiring 5 extending from the internal space S1 of the rod 2 from the main body through the openings 2a, 34c, and the housing space S2 of the base 34 to the motor 4. Furthermore, these gaps V1 and V2 also function as air passages. Note that other electronic components (not shown) may be disposed in the gap V1.

[0019] FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 2. Referring to FIGS. 2, 3, 5, and 7 in combination, a mount 38 is attached to the heat sink 35. For attachment, fixing members 39 such as screws are used, which are arranged adjacent to the four corners of the base plate 35a of the heat sink 35 (see FIG. 5). A substrate 37 is disposed between the heat sink 35 and the mount 38. As shown in FIG. 7, the mount 38 has an overall circular shape with a portion cut out in an arch shape when viewed in a plan view in the rotational axis direction. The mount 38 is configured to support the motor 4. The mount 38 is formed from, for example, a resin material.

[0020] A motor 4 according to one specific example includes a holder 42 fixed to a mount 38. The holder 42 includes a cylindrical inner circumferential portion (hereinafter referred to as the "inner circumferential portion") 43 centered on the rotation axis x2, a cylindrical outer circumferential portion (hereinafter referred to as the "outer circumferential portion") 44 centered on the rotation axis x2, and a portion (hereinafter referred to as the "connecting portion") 45 connecting the inner circumferential portion 43 and the outer circumferential portion 44 to each other. As shown in FIG. 7 , in this example, four connecting portions 45 connect the inner circumferential portion 43 and the outer circumferential portion 44 to each other. Each connecting portion 45 extends from the lower end of the inner circumferential portion 43 in a radial direction perpendicular to the rotation axis x2. The holder 42 is supported on the mount 38 by the lower surface of the connecting portion 45. The inner circumferential portion 43, the outer circumferential portion 44, and the connecting portion 45 are integrally formed from, for example, a resin material.

[0021] A stator 46 is fixed to the outer peripheral surface of the outer cylinder portion 44. The stator 46 includes a stator core 47, a plurality of coils 48, and a plurality of insulators (not shown). The stator core 47 is formed from a laminate of a magnetic material, such as silicon steel plate, and functions as a yoke for the stator 46. As shown in FIG. 7 , the stator core 47 includes a plurality of teeth 47a each extending radially outward in a direction perpendicular to the rotation axis x2. A coil 48 is wound around each tooth 47a. An insulator made of an insulating material is disposed between the teeth 47a and the coils 48. Electrical insulation is thus established between the stator core 47 and the coils 48. A magnetic pole portion 47b is formed at the outer peripheral end of each tooth 47a of the stator core 47.

[0022] Meanwhile, the inner circumferential surface of the inner cylindrical portion 43 holds the outer rings of two bearings 49, 49 arranged along the rotation axis x2. The bearings 49, 49 are fitted into the inner circumferential surface of the inner cylindrical portion 43 and fixed to the inner circumferential surface with an adhesive. The bearings 49, 49 are, for example, ball bearings. However, other bearings, such as sleeve bearings, may also be used for the bearings 49, 49. The rotating shaft 41 is held in the inner rings of the bearings 49, 49. In this manner, the rotating shaft 41 is supported by the inner cylindrical portion 43, i.e., the holder 42, rotatably around the rotation axis x2 via the bearings 49, 49. A flat, cylindrical pusher 50 is attached to the lower end of the inner cylindrical portion 43 of the holder 42. In this example, the pusher 50 can apply a predetermined pressure to the outer ring of the lower bearing 49 in the rotation axis direction.

[0023] The motor 4 has a rotor, i.e., a housing 51, attached to the rotary shaft 41. The housing 51 can rotate together with the rotary shaft 41 around the rotation axis x2. In this example, the housing 51 extends radially outward beyond the holder 42. The motor 4 has a cover 52 fixed to an annular outer peripheral edge 51a of the housing 51. The cover 52 is formed in a cylindrical shape centered on the rotation axis x2. The cover 52 extends downward from the outer peripheral edge 51a of the housing 51 to the bottom plate 34a of the base 34. In this example, the cover 52 is attached to the outer peripheral edge 51a of the housing 51 with one or more fixing members 53, such as screws. However, the cover 52 may also be attached to the edge 51a of the housing 51 by other fixing methods, such as adhesive, welding, or crimping.

[0024] A cylindrical yoke 54 is attached to the inner circumferential surface of the cover 52. A cylindrical magnet 55 is attached to the inner circumferential surface of the yoke 54. The yoke 54 is formed, for example, from a magnetic material. The magnet 55 is, for example, a permanent magnet. The magnet 55 may be a single cylindrical permanent magnet, or multiple permanent magnets may be connected circumferentially around the rotation axis x2 to form a cylindrical shape. The inner circumferential surface of the magnet 55 faces the magnetic pole portion 47b of the stator core 47 in the radial direction with a predetermined magnetic gap between them. When a current is supplied to the coil 48, a magnetic interaction is generated between the coil 48 and the magnet 55. This magnetic interaction allows the magnet 55, i.e., the housing 51 and the cover 52, to rotate around the rotation axis x2.

[0025] FIG. 8 is a cross-sectional perspective view taken along line 8-8 in FIG. 2. Referring to FIGS. 2, 3, and 8 together, the cover 52 has one or more (16 in this example) fins 56 formed on the inner circumferential surface of the cover 52 below the yoke 54 and the magnet 55 in the rotational axis direction. Each fin 56 extends flat along an imaginary plane including the rotational axis x2. The fins 56 are integrally formed on the inner circumferential surface of the cover 52. In this example, the inner circumferential ends of the fins 56 face the outer circumferential surfaces of the mount 38 and the holder 42 across a predetermined gap. The upper ends of the fins 56 face the stator core 47 and the coils 48, while the lower ends of the fins 56 face the substrate 37. Thus, the stator 46, i.e., the stator core 47 and the coils 48, are disposed between the housing 51 and the multiple fins 56 in the rotational axis direction.

[0026] The dimensions, shape, thickness, number, etc. of the fins 56 may be appropriately set depending on the size and heat generation amount of the motor 4. In the example of FIG. 8 , the fins 56 extend in a flat plate shape along an imaginary plane including the rotation axis x2. However, for example, the fins 56 may be formed in a flat plate shape inclined in the circumferential direction with respect to the imaginary plane including the rotation axis x2. Furthermore, the fins 56 may be formed in a shape curved in the circumferential direction with respect to the imaginary plane including the rotation axis x2. Furthermore, the fins 56 may be formed in a flat plate shape inclined about a radial axis defined in the radial direction. Furthermore, the radial dimensions of the fins 56 may be increased by reducing the diameters of the outer peripheral surfaces of the mount 38 and the holder 42. The fins 56 and the cover 52 may be integrally formed from, for example, a resin material, a metal material, or the like.

[0027] The cover 52 has, for example, a circular opening 52a at its lower end. In this example, the positions of the bottom plate 34a of the base 34 and the opening 52a of the cover 52 are substantially aligned in the rotational axis direction. That is, the entire outer peripheral surface of the side wall 34b of the base 34 faces the inner peripheral surface of the cover 52 in the radial direction. Thus, an annular gap G is formed between the inner peripheral surface of the cover 52 and the outer peripheral surface of the side wall 34b of the base 34 in the radial direction. An internal space S3 inside the cover 52 (including the storage space S2 formed by the base 34) of the motor 4 formed by the cover 52 is connected to an external space outside the cover 52 via the gap G and the opening 52a of the cover 52. In this example, the distance between the inner peripheral surface of the cover 52 and the outer peripheral surface of the side wall 34b of the base 34 is set constant in the rotational axis direction. The area of ​​the gap G defined in an imaginary plane perpendicular to the rotation axis x2 is set smaller than the area of ​​the opening 34c defined in an imaginary plane perpendicular to the rotation axis x2.

[0028] When the rotating shaft 41 rotates around the rotation axis x2, the housing 51 and the cover 52 rotate along with the rotating shaft 41. The fins 56 also rotate around the rotation axis x2. Because the area of ​​the gap G is smaller than the area of ​​the opening 34c, a pressure difference causes air to be introduced from the external space into the internal space S3 of the cover 52 through the opening 2a of the rod 2 and the opening 34c of the base 34, as shown by arrow A in FIG. 9 . Heat from the heat sink 35, the substrate 37, the stator core 47, and the coils 48 is transferred to the air introduced into the internal space S3 inside the cover 52. The pressure difference causes the heated air to flow out into the external space through the gap G between the outer peripheral surface of the side wall 34b of the base 34 and the inner peripheral surface of the cover 52. In this way, the heat sink 35, the substrate 37, the stator core 47, and the coils 48 are cooled.

[0029] In the unmanned vehicle 1 described above, heat from the electronic components 37a mounted on the circuit board 37 is conducted from the heat sink 35 in contact with the electronic components 37a to the bottom plate 34a of the base 34 and the support base 32 of the attachment 3, and then released to the outside. Furthermore, as the rotation shaft 41 rotates, the fins 56 rotate about the rotation axis x2, introducing air into the internal space S3 of the cover 52 through the openings 34c in the bottom plate 34a of the base 34. This air passes through the internal space S3 of the cover 52, further through the stator 46 (the internal space formed between the stator core 47 and the inner cylinder portion 43), through the space between the stator 46 and the rotor 51 (the magnet 55), and is discharged to the outside through the gap G between the outer peripheral surface of the side wall 34b of the base 34 and the inner peripheral surface of the cover 52. The air flow thus generated can cool the heat sink 35, the circuit board 37, the stator core 47, and the coil 48. In this way, the heat dissipation properties of both the motor 4 and the ESC can be improved.

[0030] Furthermore, a gap G between the outer peripheral surface of the side wall 34b of the base 34 and the inner peripheral surface of the cover 52 constitutes a flow path for air to flow from the internal space S3 formed by the cover 52 to the external space. Because the gap G is a narrow space where the outer peripheral surface of the side wall 34b and the inner peripheral surface of the cover 52 face each other, the inflow of dust and liquid into the internal space S3 of the cover 52 through this gap G can be prevented. This improves the dustproof and waterproof performance of the motor 4. In this example, the inner peripheral surface of the cover 52 faces the entire outer peripheral surface of the side wall 34b. However, the inner peripheral surface of the cover 52 may face at least a portion of the outer peripheral surface of the side wall 34b. Furthermore, the distance between the outer peripheral surface of the side wall 34b of the base 34 and the inner peripheral surface of the cover 52 does not have to be constant in the rotational axis direction. For example, the distance may increase or decrease upward in the rotational axis direction.

[0031] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0032] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, and size, are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes variations that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the aforementioned problems and effects.

[0033] 1 drone, 2 rod, 2a opening, 3 attachment, 4 motor, 5 wiring, 31 flange, 32 base (support base), 33 portion (connecting arm), 34 base, 34a bottom plate, 34b side wall, 34c opening, 35 heat dissipation component (heat sink), 35a base plate, 35b block, 35c slit, 35d heat dissipation fin, 36 fixing member, 37 substrate, 37a electronic component, 38 mount, 39 fixing member, 41 rotating shaft, 42 holder, 43 cylindrical portion (inner cylindrical portion), 44 cylindrical portion (outer cylindrical portion), 45 portion (connecting portion), 46 stator, 47 stator core, 47a teeth, 47b magnetic pole portion, 48 coil, 49 bearing, 50 pusher, 51 rotor (housing), 51a edge portion, 52 Cover, 52a: opening, 53: fixing member, 54: yoke, 55: magnet, 56: fin, G: gap, S1: internal space (space), S2: storage space, S3: internal space (space), V1, V2: gap, x1: central axis, x2: rotation axis

Claims

1. A motor comprising: a stator; a rotor; and a cover fixed to the rotor, the cover having one or more fins, the stator being disposed between the rotor and the fins in the direction of the rotation axis.

2. An unmanned vehicle comprising: a motor as claimed in claim 1; a base having an opening connected to the outside; and an attachment supporting said base, wherein a gap is formed between said cover and said base in the radial direction, and the space inside said cover is connected to the outside via said gap and the opening in said cover.

3. An unmanned aerial vehicle as described in claim 2, comprising: a substrate; and electronic components mounted on said substrate; a heat sink is mounted on said base; and said electronic components face said heat sink.

4. An unmanned aerial vehicle as described in claim 2 or 3, further comprising a rod connected to the attachment, the inner space of the rod being connected to the opening of the base.

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