Motor

Abstract

A motor (1) comprises: a stator (39) that has a magnetic body (37) having a plurality of magnetic pole parts (46), and a plurality of coils (38) wound around the magnetic body (37); a rotor (26); and a heat dissipation member (47) that is in contact with one end parts (38a or 38b) of the coils (38) in the rotation axis direction of the rotor (26) directly or through another member (54). The heat dissipation member (47) is disposed so as to be detachable from and attachable to the stator (39).

Description

Motor

[0001] The present invention relates to a motor.

[0002] When a current is supplied to a coil in a motor, the coil generates heat. Patent Document 1 discloses a motor having a heat sink for dissipating the heat generated by the coil. The heat sink is sandwiched and fixed between the yoke and the substrate.

[0003] Japanese Patent Application Laid-Open No. 2007-143205

[0004] The current value supplied to the coil is determined by the motor's output. When the output is large, the amount of heat generated also increases. There is a demand for the size of the heat sink to be able to change depending on the increase or decrease in output and heat generation.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor in which the heat dissipation member can be replaced depending on the output.

[0006] A motor according to one aspect of the present invention comprises a stator having a magnetic body with a plurality of magnetic pole portions and a plurality of coils wound around the magnetic body, a rotor, and a heat dissipation member that contacts one end of the coil in the direction of the rotor's rotational axis directly or via another member, and the heat dissipation member is arranged so as to be detachable from the stator.

[0007] FIG. 1 is a perspective view showing a schematic structure of a motor 1 according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of the motor 1 taken along line 2-2 in FIG. 1. FIG. 3 is a perspective view of the motor 1 from above with the upper cover 14 removed. FIG. 4 is a perspective cross-sectional view taken along line 4-4 in FIG. 1. FIG. 5 is an exploded perspective view of the motor 1 in FIG. 3. FIG. 6 is a cross-sectional view of the motor 1 taken along line 6-6 in FIG. 4. FIG. 6 is a perspective view of the motor 1 showing a schematic structure of a heat dissipation member 47 according to a modified example.

[0008] An embodiment of the present invention will now be described with reference to the accompanying drawings. Figures 1 and 2 are perspective views schematically showing the structure of a motor 1 according to an embodiment of the present invention. Figure 1 is a perspective view of the motor 1 as seen from above, i.e., one side, in a direction (hereinafter referred to as the "rotational axis direction") along a rotation axis (hereinafter referred to as the "axis") x that constitutes the rotational axis of the motor 1. Figure 2 is a cross-sectional view of the motor 1 taken along line 2-2 in Figure 1. This cross-sectional view is a vertical cross-sectional view taken along an imaginary plane including the axis x.

[0009] In the following description of this embodiment, the upper and lower sides defined in the direction of the rotation axis do not necessarily correspond to the upper and lower positions in the direction of gravity. Furthermore, the radial direction of the motor 1 is defined as a direction perpendicular to the axis x. In this radial direction, the side away from the axis x is defined as the outer circumferential side, while the side approaching the axis x is defined as the inner circumferential side. Furthermore, the circumferential direction of the motor 1 is defined around the axis x. In this circumferential direction, clockwise and counterclockwise directions are defined around the axis x when the motor 1 is viewed from above.

[0010] 1 and 2 , the motor 1 includes, for example, a cylindrical shaft 10 with its central axis coincident with axis x. In this example, the upper and lower ends of the shaft 10 along axis x are open. Two bearings 11 and 12 are attached to the outer circumferential surface of the shaft 10 along the direction of the rotation axis. The bearings 11 and 12 are, for example, ball bearings. The bearings 11 and 12 are attached to the shaft 10 by, for example, press fitting, clearance fit, or the like. The motor 1 includes a housing 13 supported by the bearings 11 and 12 for rotation around axis x. The housing 13 includes an upper cover 14 supported by the upper bearing 11 and a lower cover 15 supported by the lower bearing 12.

[0011] The upper cover 14 has an inner cylindrical portion (hereinafter referred to as the "inner portion") 16, a portion (hereinafter referred to as the "annular portion") 17 extending annularly from the inner portion 16 toward the outer periphery, and an outer cylindrical portion (hereinafter referred to as the "outer portion") 18 extending downward from the outer periphery end of the annular portion 17. The annular portion 17 extends in a flat plate shape along an imaginary plane perpendicular to the axis x, for example. The inner portion 16 protrudes upward from the annular portion 17 in a cylindrical shape. The upper end of the inner portion 16 is closed.

[0012] The lower cover 15 has an inner cylindrical portion (hereinafter referred to as the "inner portion") 20, a portion (hereinafter referred to as the "annular portion") 21 extending annularly from the inner portion 20 toward the outer periphery, and an outer cylindrical portion (hereinafter referred to as the "outer portion") 22 extending upward from the outer periphery of the annular portion 21. A circular opening 23 is formed in the inner portion 20 around the axis x. The shaft 10 passes through the opening 23 in the inner portion 20 and protrudes downward from the lower cover 15 along the axis x. The annular portion 21 extends, for example, in a flat plate shape along an imaginary plane perpendicular to the axis x. The upper cover 14 and the lower cover 15 are formed, for example, from a resin material or a metal material.

[0013] A cylindrical yoke 24 is sandwiched and fixed between the outer periphery 18 of the upper cover 14 and the outer periphery 22 of the lower cover 15. The yoke 24 is made of, for example, a magnetic material. A cylindrical magnet 25 is fixed to the inner periphery of the yoke 24. The magnet 25 is attached to the inner periphery of the yoke 24 with, for example, an adhesive. The magnet 25 is made of, for example, a permanent magnet. The yoke 24 and the magnet 25 form a rotor 26 of the motor 1. In other words, the motor 1 is an outer rotor type motor. The magnet 25 may be a single cylindrical permanent magnet, or may be a cylindrical shape formed by connecting multiple permanent magnets circumferentially.

[0014] The outer peripheral surfaces of the outer peripheral portion 18 and the outer peripheral portion 22 are respectively formed with a plurality of protrusions 27 and a plurality of protrusions 28 that protrude outward. In this example, for example, six protrusions 27 and six protrusions 28 are arranged at equal intervals in the circumferential direction. The positions of the protrusions 27 and the protrusions 28 about the axis x are defined to be the same. Each protrusion 27 is formed with a through hole 29 that extends along the axis x, while each protrusion 28 is formed with a threaded hole 30 that also extends along the axis x. Fasteners, i.e., screws 31, are threaded through the through holes 29 and into the threaded holes 30, thereby joining the upper cover 14 and the lower cover 15 to each other. In this manner, the interior space of the motor 1 is sealed by the housing 13 and the yoke 24.

[0015] A base 32 is fixed to the lower end of the shaft 10 below the lower bearing 12 in the direction of the rotation axis. The base 32 has a cylindrical portion (hereinafter referred to as the "support portion") 33 supported on the outer circumferential surface of the shaft 10, and a portion (hereinafter referred to as the "flange portion") 34 extending annularly from the lower end of the support portion 33 toward the outer periphery. The support portion 33 and the flange portion 34 are formed, for example, by integral molding using a resin material. A plurality of screw holes 35 are formed in the flange portion 34, for example, parallel to the axis x. Fasteners such as screws are threaded into these screw holes 35 to attach the motor 1 to an unmanned aerial vehicle such as a drone.

[0016] Figure 3 is a perspective view of the motor 1 seen from above with the upper cover 14 removed. Figure 4 is a perspective cross-sectional view taken along line 4-4 in Figure 1. The cross section of this perspective cross-sectional view is a horizontal cross section taken along an imaginary plane perpendicular to the axis x. Referring to Figures 2 to 4 together, the motor 1 includes a holder 36 attached to the shaft 10 between the two bearings 11 and 12, a magnetic body (i.e., a stator core 37) attached to the outer circumferential surface of the holder 36, and a plurality of coils 38 wound around the stator core 37. The holder 36, stator core 37, and coils 38 form a stator 39 of the motor 1.

[0017] The holder 36 has an annular portion (hereinafter referred to as the "mounting portion") 40 attached to the outer circumferential surface of the shaft 10, an annular portion (hereinafter referred to as the "supporting portion") 41 arranged radially outward from the mounting portion 40 and supporting the stator core 37, and a plurality of (e.g., eight) connecting portions 42 interconnecting the mounting portion 40 and the supporting portion 41. The mounting portion 40 is, for example, press-fitted into the outer circumferential surface of the holder 36. Each connecting portion 42 extends radially. In this example, the connecting portions 42 are arranged at equal intervals in the circumferential direction. The stator core 37 is attached to the outer circumferential surface of the supporting portion 41. The holder 36 is formed from, for example, a metal material such as aluminum or a resin material.

[0018] The stator core 37 is formed from a laminate of magnetic materials such as silicon steel plates. The stator core 37 functions as a yoke for the stator 39. As is clear from FIG. 4 , the stator core 37 has a cylindrical portion (hereinafter referred to as the "cylindrical portion") 43 and a plurality of (e.g., 24) teeth 44 extending outward from the outer circumferential surface of the cylindrical portion 43. Each tooth 44 has a spoke 45 whose inner end is connected to the outer circumferential surface of the cylindrical portion 43, and a magnetic pole portion 46 continuing from the outer circumferential end of the spoke 45. The outer circumferential surface of the magnetic pole portion 46 faces the inner circumferential surface of the magnet 25 with a predetermined magnetic gap therebetween.

[0019] A coil 38 is wound around each spoke 45. The winding axis of the coil 38 is radial. An insulator (not shown) is disposed between the spoke 45 and the coil 38. The insulator insulates the stator core 37 from the coil 38. In this example, the magnet 25 has an S-pole region 25a magnetized to an S-pole and an N-pole region 25b magnetized to an N-pole. The S-pole regions 25a and the N-pole regions 25b are arranged alternately in the circumferential direction. In this manner, a region where the magnetic polarity changes is defined between the S-pole region 25a and the N-pole region 25b. When a current is supplied to the coil 38, the rotor 26 and the housing 13 rotate, for example, clockwise or counterclockwise around the axis x due to interaction with the magnetic field generated by the magnet 25.

[0020] FIG. 5 is an exploded perspective view of the motor 1 of FIG. 3. Referring to FIGS. 2, 3, and 5, the motor 1 includes at least one heat dissipation member 47 that contacts one of the ends 38a, 38b of the coil 38 in the rotational axis direction. The ends 38a and 38b correspond to the upper and lower surfaces of the coil 38. In this example, the heat dissipation member 47 contacts both ends 38a, 38b of the coil 38. Each heat dissipation member 47 includes an annular main body 48 and one or more (e.g., four) protrusions 49 that protrude inward from the inner circumferential end of the main body 48. The protrusions 49 are arranged at equal intervals in the circumferential direction. Each protrusion 49 has a through-hole 50 that penetrates the protrusion 49 in a direction parallel to the axis x.

[0021] One or more portions (hereinafter referred to as "mounting portions") 51 extending parallel to the axis x are formed on the inner circumferential surface of the support portion 41 of the holder 36. In this example, four mounting portions 51 are formed at positions corresponding to the protrusions 49 of the heat dissipation member 47. Each mounting portion 51 has a through hole 52 extending parallel to the axis x. A thread groove (not shown) is cut on the inner circumferential surface of the through hole 52. As shown in FIGS. 2 and 5 , the heat dissipation member 47 is attached to the holder 36 by threading a fastening part, i.e., a screw 53, into the through hole 52 through the through hole 50 of the protrusion 49.

[0022] In this example, the lower surface of the main body 48 of the upper heat dissipation member 47 contacts or faces the end 38a of the coil 38, while the upper surface of the main body 48 of the lower heat dissipation member 47 contacts or faces the end 38b of the coil 38. As is apparent from FIG. 2 , the upper surface of the main body 48 of the upper heat dissipation member 47 faces the inner surface of the annular portion 17 of the upper cover 14 with a predetermined gap therebetween. Meanwhile, the lower surface of the main body 48 of the lower heat dissipation member 47 faces the inner surface of the annular portion 21 of the lower cover 15 with a predetermined gap therebetween. The outer peripheral ends of each main body 48 face the outer periphery, i.e., face the inner periphery of the outer periphery 18 of the upper cover 14 and the inner periphery of the outer periphery 22 of the lower cover 15, respectively. The two heat dissipation members 47, 47 have the same shape and are arranged within the motor 1 so as to be plane-symmetrical with respect to an imaginary plane perpendicular to the axis x.

[0023] Another member, i.e., heat dissipation resin 54, is sandwiched between the heat dissipation member 47 and the ends 38a, 38b of the coil 38. The heat dissipation resin 54 is, for example, a clay-like or grease-like thermally conductive material that is fluid and can maintain its shape. The heat dissipation resin 54 is formed from a resin material such as EPDM or silicone. The heat dissipation resin 54 can change its shape depending on the outer shapes of the coil 38 and the heat dissipation member 47. As a result, the heat dissipation resin 54 can contact the coil 38 and the heat dissipation member 47 without any gaps. In this example, the heat dissipation resin 54 is arranged in a continuous ring shape in the circumferential direction between the coil 38 and the heat dissipation member 47.

[0024] FIG. 6 is a cross-sectional view of the motor 1 taken along line 6-6 in FIG. 4. This cross-sectional view is a vertical cross-sectional view taken along an imaginary plane parallel to the axis x. As shown in FIGS. 3, 5, and 6, one or more recesses, i.e., grooves 55, are formed on the upper surface of the main body 48 of the heat dissipation member 47 in the direction of the rotational axis. Each groove 55 extends radially. Because the main body 48 is formed in a flat plate shape, the grooves 55 on the upper surface of the main body 48 form convex portions, i.e., slender protruding portions, called ridges 56, on the lower surface of the main body 48 corresponding to the grooves 55. Each ridge 56 extends radially. In this example, the heat dissipation member 47 is formed by press working from a metal material such as aluminum, iron, or copper. That is, the grooves 55 and ridges 56 are simultaneously formed in the main body 48 by press working.

[0025] As is clear from FIG. 6 , the positions of the grooves 55 and the ridges 56 in the circumferential direction in a plan view correspond to the positions of boundary positions 57 between circumferentially adjacent coils 38, 38. The boundary positions 57 are, for example, boundary surfaces between the coils 38, 38 defined along an imaginary plane including the axis x. Because the coils 38 are wound around the spokes 45, radially extending grooves 58 are formed on the upper and lower sides between the coils 38, 38 in the cross section shown in FIG. 6 . Each groove 55 in the heat dissipation member 47 is arranged along this groove 58. In this example, as shown in FIG. 2 , the outer peripheral end of the main body 48 of the heat dissipation member 47 extends radially to approximately the same position as the outer peripheral end of the coil 38.

[0026] During assembly of the motor 1, prior to attaching the heat dissipation member 47 to the holder 36, heat dissipation resin 54 is applied to the ends 38a, 38b of the coil 38. The heat dissipation member 47 is then attached to the holder 36 using screws 53. At this time, the body 48 of the heat dissipation member 47 is pressed against the ends 38a, 38b of the coil 38. As a result, the heat dissipation resin 54 can change shape between the body 48 and the coil 38 due to its own fluidity. Specifically, as shown in FIG. 6 , the ridges 56 of the heat dissipation member 47 can bite into the upper surface of the heat dissipation resin 54. In this way, the heat dissipation resin 54 can reliably adhere to the body 48 and the coil 38, conforming to their shapes.

[0027] In the motor 1 described above, when current is supplied to the coil 38, the coil 38 generates heat. The heat from the coil 38 is transferred to the heat dissipation member 47 through the heat dissipation resin 54. The transferred heat is dissipated from the main body 48 of the heat dissipation member 47 into the space within the housing 13. This prevents the coil 38 from excessively increasing in temperature. The heat dissipation member 47 is detachably attached to the holder 36 with screws 53. Therefore, for example, if the amount of current supplied to the coil 38 is changed to match the output of the motor 1, the heat dissipation member 47 can be replaced with one of a different size, i.e., surface area, to accommodate the change. As a result, a heat dissipation member 47 with the minimum necessary surface area can be used, thereby reducing the weight of the motor 1.

[0028] Furthermore, the main body 48 of the heat dissipation member 47 has, for example, grooves 55 and ridges 56 extending radially. The formation of these grooves 55 and ridges 56 increases the surface area of ​​the main body 48, thereby improving the heat dissipation performance of the heat dissipation member 47. Furthermore, the circumferential positions of the grooves 55 and ridges 56 coincide with the positions of the grooves 58 at the boundary positions 57 between adjacent coils 38. This configuration allows the main body 48 to contact the coils 38 with sufficient tightness, and the heat dissipation member 47 can more efficiently dissipate heat from the coils 38. Furthermore, heat is also transferred to the holder 36 via the protrusions 49 of the heat dissipation member 47 and the stator core 37. The transferred heat is released from the holder 36 into the space within the housing 13, further improving the heat dissipation performance.

[0029] FIG. 7 corresponds to FIG. 3 and is a perspective view of the motor 1, schematically illustrating the structure of a heat dissipation member 47 according to one modification. As shown in FIG. 7 , in the heat dissipation member 47 according to one modification, the main body 48 may have flat upper and lower surfaces. That is, the main body 48 does not have grooves 55 or ridges 56 formed therein. In other words, the flat lower surface of the heat dissipation member 47 contacts the heat dissipation resin 54. This heat dissipation member 47 has a simpler shape than the heat dissipation member 47 having grooves 55 and ridges 56, and therefore can be manufactured more easily and at reduced manufacturing costs.

[0030] In the motor 1 described above, the incorporation of the heat dissipation resin 54 may be omitted. That is, the heat dissipation member 47 may be in direct contact with the ends 38a, 38b of the coil 38, rather than through the heat dissipation resin 54. In this case, the body 48 of the heat dissipation member 47 may have a shape that conforms to the shape of the ends 38a, 38b of the coil 38. Furthermore, gaps may be formed between the upper surface of the upper heat dissipation member 47 and the lower surface of the lower heat dissipation member 47 and the inner surfaces of the upper cover 14 and lower cover 15 of the housing 13. Therefore, for example, protrusions may be further formed on the upper surface of the upper heat dissipation member 47 and the lower surface of the lower heat dissipation member 47. These protrusions may further increase the surface area of ​​the heat dissipation member 47.

[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 present invention. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be modified as appropriate. Furthermore, components shown in different embodiments can be partially substituted or combined with each other within the scope of technical inconsistency.

[0033] REFERENCE SIGNS LIST 1 motor, 10 shaft, 11 bearing, 12 bearing, 13 housing, 14 upper cover, 15 lower cover, 16 portion (inner peripheral portion), 17 portion (annular portion), 18 portion (outer peripheral portion), 20 portion (inner peripheral portion), 21 portion (annular portion), 22 portion (outer peripheral portion), 23 opening, 24 yoke, 25 magnet, 25a south pole region, 25b north pole region, 26 rotor, 27 protrusion, 28 protrusion, 29 through hole, 30 screw hole, 31 screw (fastening part), 32 base, 33 portion (support portion), 34 portion (flange portion), 35 screw hole, 36 holder, 37 stator core (magnetic material), 38 coil, 38a end, 38b end, 39 stator, 40 portion (mounting portion), 41 portion (support portion), 42 connection portion, 43 Part (cylindrical part), 44 Teeth, 45 Spokes, 46 Magnetic pole part, 47 Heat dissipation member, 48 Main body part, 49 Projection piece, 50 Through hole, 51 Part (mounting part), 52 Through hole, 53 Screw (fastening part), 54 Heat dissipation resin, 55 Groove (recess), 56 Convex part (protrusion), 57 Boundary position, 58 Groove, x Rotation axis (axis)

Claims

1. A motor comprising: a stator having a magnetic body with multiple magnetic pole portions and multiple coils wound around the magnetic body; a rotor; and a heat dissipation member that contacts one end of the coil in the direction of the rotational axis of the rotor directly or via another member, wherein the heat dissipation member is arranged so as to be detachable from the stator.

2. The motor according to claim 1, wherein the heat dissipation member contacts both ends of the coil in the direction of the rotation axis, either directly or via another member.

3. A motor according to claim 1 or 2, wherein the motor comprises a housing forming a space for accommodating the stator, and the heat dissipation member faces an inner surface of the housing in the direction of the rotation axis of the rotor.

4. The motor according to any one of claims 1 to 3, wherein the winding axis of said coil is in the radial direction of said rotor.

5. The motor according to any one of claims 1 to 4, wherein an outer peripheral end of said heat dissipation member faces the outer peripheral side in the radial direction of said rotor.

6. The motor according to any one of claims 1 to 5, wherein the other member is a heat dissipating resin.

7. The motor according to any one of claims 1 to 6, wherein a concave or convex portion is formed on a surface of said heat dissipation member in the direction of the rotation axis of said rotor.

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