Electric motor

Abstract

This electric motor comprises: a rotor having a rotary shaft; a stator for generating a magnetic force that acts on the rotor; and a radiator positioned on the opposite side from the output shaft-side of the rotary shaft and constituting at least a part of an outer shell of the electric motor. The radiator has a base and a plurality of heat-radiating fins that are erect on the outer surface of the base. The outer surface of the base has a dome shape that is convex toward the exterior of the electric motor. The plurality of heat-radiating fins are provided such that a plurality of air passages are formed from the center of the base toward the outside.

Description

electric motor

[0001] The present disclosure relates to electric motors.

[0002] Electric motors are used in a variety of electrical appliances, including household and industrial electrical appliances. For example, fan motors with a rotary fan attached to a rotating shaft are known as electric motors used in air conditioners, electric vacuum cleaners, etc. The fan motor in an air conditioner is mounted in, for example, an outdoor unit to promote heat exchange with a heat exchanger.

[0003] When the temperature of an electric motor rises, the performance and life of the electric motor deteriorate. Therefore, electric motors equipped with radiators having heat dissipation fins have been proposed to prevent the temperature of the electric motor from rising (see, for example, Patent Document 1). A radiator with a fan motor attached to the radiator has also been proposed (see, for example, Patent Document 2).

[0004] However, with the conventional heat sink structure, it is difficult to sufficiently suppress the temperature rise of the electric motor.

[0005] Japanese Patent Application Laid-Open No. 2020-167846 Japanese Utility Model Application Laid-Open No. 7-29621

[0006] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide an electric motor that can effectively suppress a temperature rise in the electric motor.

[0007] In order to achieve the above object, one aspect of the electric motor according to the present disclosure comprises a rotor having a rotating shaft, a stator that generates a magnetic force acting on the rotor, and a heat sink located on the opposite side of the rotating shaft from the output shaft side and constituting at least a part of the outer shell of the electric motor, the heat sink having a base and a plurality of heat sink fins standing on the outer surface of the base, the outer surface of the base being dome-shaped and convex toward the outside of the electric motor, and the plurality of heat sink fins being arranged so as to form a plurality of air passages from the center of the base outward.

[0008] When the outer surface of the base is divided into a plurality of regions, the plurality of heat dissipation fins are preferably provided parallel to one another in each of the plurality of regions.

[0009] When viewed from the direction in which the rotation axis extends, the plurality of heat dissipation fins preferably extend outward from the center of the base in each of the plurality of regions.

[0010] When viewed from a direction in which the rotation axis extends, the heat dissipation fin may extend in a spiral shape.

[0011] It is preferable that the electric motor further includes a bearing that supports the rotary shaft, and that a recess for accommodating the bearing is provided on the inner surface of the base.

[0012] It is preferable that the stator is covered by a molded resin that forms part of the outer shell of the motor, the molded resin is formed to have an opening, the rotor is housed in the molded resin, and the base is arranged to cover the opening in the molded resin.

[0013] It is preferable that the electric motor further includes a circuit board on which a heat-generating component is mounted, the heat-generating component being located close to the inner surface of the base.

[0014] The heat generating component may be a semiconductor element.

[0015] The heat generating component is preferably in contact with the inner surface of the base.

[0016] The outer surface of the base is preferably spherical.

[0017] The outer surface of the base may be a conical surface.

[0018] The outer surface of the base may be formed in a stepped shape.

[0019] According to the present disclosure, the temperature rise of the electric motor can be effectively suppressed.

[0020] FIG. 1 is a perspective view of an electric motor according to an embodiment when viewed from the output shaft side. FIG. 2 is a perspective view of an electric motor according to an embodiment when viewed from the non-output shaft side. FIG. 3 is a half sectional view of an electric motor according to an embodiment. FIG. 4 is a plan view of an electric motor according to an embodiment when viewed from the non-output shaft side. FIG. 5 is a perspective view of an electric motor of a comparative example when viewed from the non-output shaft side. FIG. 6 is a plan view of an electric motor of the comparative example when viewed from the non-output shaft side. FIG. 7 is a half sectional view of an electric motor of the comparative example. FIG. 8 is a diagram for explaining the effects of an electric motor according to an embodiment. FIG. 9A is a diagram showing heat distribution when the electric motor of the comparative example shown in FIG. 7 is used. FIG. 9B is a diagram showing heat distribution when the electric motor according to the embodiment shown in FIG. 8 is used. FIG. 10 is a half sectional view of an electric motor of Modification 1. FIG. 11 is a half sectional view of an electric motor of Modification 2. FIG. 12 is a plan view of an electric motor of Modification 3 when viewed from the non-output shaft side.

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0022] Each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. In all figures, the same reference numerals are used for substantially the same components, and duplicated explanations are omitted or simplified. In cross-sectional views, basically only the parts that appear in the cross section are shown.

[0023] In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition. In this embodiment, the radial direction of the stator 10 and the rotor 20 is referred to as the "radial direction," and the direction in which the rotor 20 rotates (the rotation direction) is referred to as the "circumferential direction." In other words, the direction extending from the axis C of the rotating shaft 21 as the center is the "radial direction," and the direction going around the axis C of the rotating shaft 21 as the center is the "circumferential direction." Therefore, the "radial direction" is a direction perpendicular to the direction in which the axis C of the rotating shaft 21 extends (also simply referred to as the "axial direction").

[0024] (Embodiment) The configuration of an electric motor 1 according to an embodiment will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view of the electric motor 1 according to the embodiment as seen from the output shaft side. Fig. 2 is a perspective view of the electric motor 1 according to the embodiment as seen from the opposite side of the output shaft. Fig. 3 is a half cross-sectional view of the electric motor 1 according to the embodiment. Fig. 4 is a plan view of the electric motor 1 according to the embodiment as seen from the opposite side of the output shaft.

[0025] 1 to 3, the electric motor 1 includes a stator 10, a rotor 20, and a heat sink 30. The electric motor 1 further includes a circuit board 40, a first bearing 50, a second bearing 60, and a bracket 70. The electric motor 1 is a brushless motor. The electric motor 1 does not include brushes or a commutator.

[0026] The electric motor 1 is a molded motor in which the stator 10 is covered with a molded resin 80. Therefore, the electric motor 1 also includes the molded resin 80. The molded resin 80 forms the outer shell of the electric motor 1. In the electric motor 1, not only the molded resin 80 but also the heat sink 30 forms the outer shell of the electric motor 1.

[0027] As shown in Fig. 3, the stator 10 is disposed opposite the rotor 20. Specifically, the stator 10 is disposed opposite the magnetic flux generating portion 22 of the rotor 20 with a small air gap between them. Specifically, the stator 10 is disposed so as to surround the magnetic flux generating portion 22 of the rotor 20. In other words, the electric motor 1 is an inner rotor type motor in which the rotor 20 is disposed inside the stator 10.

[0028] The stator 10 generates a magnetic force that acts on the rotor 20. Specifically, the stator 10 is configured such that a plurality of N poles and S poles are alternately arranged in the circumferential direction so as to generate a magnetic flux on the air gap surface between the stator 10 and the rotor 20. The stator 10 and the rotor 20 form a magnetic circuit.

[0029] 3, the stator 10 constitutes an armature. The stator 10 includes a stator core 11, a winding 12, and an insulator 13.

[0030] The stator core 11 is an annular stator core that serves as the core of the stator 10. The stator core 11 generates a magnetic force for rotating the rotor 20. The stator core 11 is, for example, a laminated body in which a plurality of steel plates are stacked along the direction in which the axis C of the rotating shaft 21 of the rotor 20 extends. Each of the plurality of steel plates is, for example, a punched electromagnetic steel plate formed into a predetermined shape. The stator core 11 is not limited to a laminated body of a plurality of steel plates, and may also be a bulk body made of a magnetic material.

[0031] Although not shown, the stator core 11 has an annular yoke and a plurality of teeth extending toward the rotor 20. The plurality of teeth protrude from the yoke toward the rotating shaft 21. Specifically, the plurality of teeth extend radially in the radial direction toward the axis C of the rotating shaft 21. The plurality of teeth are arranged at equal intervals around the circumferential direction, with slots formed between two adjacent teeth, with the axis C of the rotating shaft 21 as the center.

[0032] The windings 12 are armature windings of the stator 10. The windings 12 are winding coils wound around the stator core 11 as stator coils. The windings 12 are wound around multiple teeth of the stator core 11. Specifically, the windings 12 are wound around each of the multiple teeth via insulators 13. In this embodiment, the windings 12 are concentrated winding coils wound around each tooth. The windings 12 are arranged in slots of the stator core 11. The windings 12 may be wound around the stator core 11 in a distributed winding manner rather than in a concentrated winding manner.

[0033] The multiple windings 12 are three-phase windings that can rotate the rotor 20 as a three-phase synchronous motor. Specifically, the multiple windings 12 are composed of unit coils for each of the three phases, U-phase, V-phase, and W-phase, which are electrically out of phase with each other by 120 degrees. In other words, the windings 12 wound around each tooth are driven by three-phase alternating current that is applied to each of the U-phase, V-phase, and W-phase units. This generates a main magnetic flux of the stator 10 in each tooth. In other words, each tooth of the stator 10 is a magnetic pole tooth. Each tooth of the stator 10 is an electromagnet that generates a magnetic force when a current flows through the windings 12.

[0034] The windings 12 of each phase are electrically connected to a circuit board 40 shown in FIG. 3. The circuit board 40 is a printed wiring board on which a plurality of wires made of a conductive material such as copper are formed in a predetermined pattern. Three connection terminals corresponding to the U-phase, V-phase, and W-phase are formed on each of the plurality of wires formed on the circuit board 40. The circuit board 40 has an opening in the center through which the rotating shaft 21 passes. The shape of the circuit board 40 in a plan view is, for example, an annular (doughnut-shaped), a sector-shaped (arc-shaped), or a C-shape.

[0035] A plurality of circuit components 41 for generating current to be supplied to the plurality of windings 12 of the stator 10 are mounted on the circuit board 40. One of the plurality of circuit components 41 is a semiconductor element 41a mounted on the circuit board 40. The semiconductor element 41a is, for example, an integrated circuit (IC) package. The plurality of circuit components 41 mounted on the circuit board 40 constitute a power supply circuit that generates three-phase AC, namely, U-phase, V-phase, and W-phase. In other words, the circuit board 40 is a power supply board.

[0036] The plurality of circuit components 41 mounted on the circuit board 40 include heat-generating components that generate heat. The heat-generating components are, for example, semiconductor elements 41 a such as IC packages or FETs (Field Effect Transistors), or coil elements such as transformers.

[0037] The circuit board 40 is fixed to the mold resin 80. The circuit board 40 is disposed between the stator core 11 and the base 31 of the heat sink 30. In this embodiment, the circuit board 40 is disposed so that the surface on which the plurality of circuit components 41 are mounted faces the heat sink 30. In this case, it is preferable that the plurality of circuit components 41 are close to the inner surface of the base 31 of the heat sink 30. In particular, it is preferable that heat-generating components such as a semiconductor element 41a are close to the inner surface of the base 31. As an example, as shown in FIG. 3 , the semiconductor element 41a, which is an IC package, is in contact with the inner surface of the base 31.

[0038] The rotor 20 rotates due to the magnetic force generated in the stator 10. The rotor 20 also generates a magnetic force. Specifically, the rotor 20 is configured with multiple alternating north and south poles that generate magnetic flux in the circumferential direction. This causes the rotor 20 to generate a magnetic force that acts on the stator 10. The direction of the magnetic flux generated from the rotor 20 is perpendicular to the direction in which the axis C of the rotating shaft 21 extends. In other words, the direction of the magnetic flux generated by the rotor 20 is radial.

[0039] As shown in FIG. 3 , the rotor 20 has a rotating shaft 21 and a magnetic flux generating section 22 that generates the main magnetic flux of the rotor 20 .

[0040] The rotating shaft 21 is a shaft having an axis C. The rotating shaft 21 is a long, rod-shaped member. As an example, the rotating shaft 21 is a metal rod made of a metal material such as SUS (Steel Use Stainless Steel). The axis C of the rotating shaft 21 serves as the center of rotation when the rotor 20 rotates. The longitudinal direction of the rotating shaft 21 is the direction in which the rotating shaft 21 extends, that is, the direction of the axis C.

[0041] The rotating shaft 21 passes through the magnetic flux generating unit 22. Therefore, both ends of the rotating shaft 21 protrude from the magnetic flux generating unit 22.

[0042] A first portion 21a, which is one portion of the rotating shaft 21 protruding to one side of the magnetic flux generating unit 22, is supported by a first bearing 50. Meanwhile, a second portion 21b, which is the other portion of the rotating shaft 21 protruding to the other side of the magnetic flux generating unit 22, is supported by a second bearing 60. The first bearing 50 and the second bearing 60 form a pair of bearings and rotatably support the rotating shaft 21. In this way, the rotating shaft 21 is rotatably supported by the first bearing 50 and the second bearing 60. This allows the rotor 20 to rotate relative to the stator 10. As an example, the first bearing 50 and the second bearing 60 are ball bearings that rotatably support the rotating shaft 21, but the present invention is not limited to this.

[0043] One end of the rotating shaft 21 is exposed to the outside of the electric motor 1. The end of the first portion 21a of the rotating shaft 21 protrudes and is exposed to the outside from the first bearing 50. Specifically, the first portion 21a of the rotating shaft 21 passes through the first bearing 50. The first portion 21a protrudes to the outside from the molded resin 80 and the bracket 70 fixed to the molded resin 80. Therefore, the first portion 21a of the rotating shaft 21 is an output shaft. A load such as a rotary fan is attached to the first portion 21a.

[0044] On the other hand, the second portion 21b of the rotating shaft 21 is not exposed to the outside of the electric motor 1. Therefore, the second portion 21b of the rotating shaft 21 is a counter-output shaft. Specifically, the second portion 21b of the rotating shaft 21 is supported by the second bearing 60. The end of the second portion 21b of the rotating shaft 21 may pass through the second bearing 60 or may be located inside the second bearing 60.

[0045] The magnetic flux generating unit 22 generates a magnetic force that acts on the stator 10. The outer peripheral surface of the magnetic flux generating unit 22 is an air gap surface that ensures an air gap between the magnetic flux generating unit 22 and the stator core 11 of the stator 10. The outer peripheral surface of the magnetic flux generating unit 22 faces the stator core 11. The magnetic flux generating unit 22 is configured so that north and south poles alternate on the air gap surface with the stator 10 along the rotation direction of the rotating shaft 21.

[0046] The magnetic flux generating unit 22 is a magnet unit having a plurality of permanent magnets 22a. In other words, the rotor 20 is a permanent magnet type rotor configured with a plurality of permanent magnets 22a. For example, the rotor 20 may be an interior permanent magnet rotor (IPM rotor), a surface-permanent magnet rotor (SPM rotor), or a rotor having another structure. When the rotor 20 is an IPM rotor, the magnetic flux generating unit 22 has a core (rotor core) and a plurality of permanent magnets 22a embedded in the core. When the rotor 20 is an SPM rotor, the magnetic flux generating unit 22 has a core and a plurality of permanent magnets 22a provided on the outer surface of the core. In these cases, the core constituting the magnetic flux generating unit 22 is a laminate in which a plurality of electromagnetic steel sheets are stacked in the direction in which the axis C of the rotating shaft 21 extends. The rotor 20 may be a coreless rotor in which the magnetic flux generating unit 22 does not have a core.

[0047] Although not shown, the multiple permanent magnets 22a are arranged at equal intervals along the circumferential direction so as to surround the rotating shaft 21. In other words, when viewed from the direction in which the axis C of the rotating shaft 21 extends, the multiple permanent magnets 22a are arranged in an annular shape. Each permanent magnet 22a is a magnetized permanent magnet. The multiple permanent magnets 22a are arranged so that south and north magnetic poles alternate along the circumferential direction.

[0048] As shown in Fig. 3, the stator 10 is covered with a molded resin 80. The molded resin 80 covers the outer portion of the stator 10 over the entire circumferential circumference of the stator 10. Specifically, the molded resin 80 covers the outer portions of the stator core 11, the windings 12, and the insulators 13. The molded resin 80 contacts the outer surfaces of the windings 12 and the insulators 13.

[0049] The mold resin 80 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The mold resin 80 is also made of a thermosetting resin. In this embodiment, the mold resin 80 is made of unsaturated polyester, which is a thermosetting resin. Specifically, the mold resin 80 is made of a white BMC (Bulk Molding Compound) unsaturated polyester resin.

[0050] As described above, the molded resin 80 forms part of the outer shell of the electric motor 1. The outer surface of the molded resin 80 includes an exposed surface. The molded resin 80, which covers the stator 10, forms a housing that encloses the rotor 20. That is, as shown in FIG. 3 , the rotor 20 is housed in the molded resin 80. The molded resin 80 is formed to have an opening. The molded resin 80 has a cylindrical portion. Openings are provided at both ends of the molded resin 80. Specifically, the molded resin 80 is formed with a first opening 81 on one side in the axial direction of the rotating shaft 21 and a second opening 82 on the other side in the axial direction of the rotating shaft 21. The first opening 81 is an opening on the output shaft side. The second opening 82 is an opening on the non-output shaft side. The first opening 81 is located on the first bearing 50 side. The second opening 82 is located on the second bearing 60 side.

[0051] A first opening 81 formed in the molded resin 80 is covered by the bracket 70. The bracket 70 closes the first opening 81. The bracket 70 is fixed to the molded resin 80. The bracket 70 is configured from a metal plate made of a metal material such as iron. The bracket 70 holds the first bearing 50. The first bearing 50 is disposed in a recess 71 provided in the bracket 70 and fixed to the bracket 70. A through hole through which the rotating shaft 21 passes is formed in the bracket 70.

[0052] The second opening 82 formed in the molded resin 80 is covered with the heat sink 30. The heat sink 30 is arranged so as to close the second opening 82. The heat sink 30 is arranged facing the magnetic flux generating unit 22 in the direction of the axis C of the rotating shaft 21. The heat sink 30 is located on the opposite side of the rotating shaft 21 from the output shaft side (i.e., the anti-output shaft side). In other words, the heat sink 30 is arranged on the anti-output shaft side of the output shaft side and the anti-output shaft side of the rotor 20 (magnetic flux generating unit 22).

[0053] The radiator 30 functions as a heat sink for radiating heat generated by the electric motor 1. The radiator 30 radiates, for example, heat generated by heat source components among the various components that make up the electric motor 1. As shown in Figures 1 to 3, the radiator 30 forms at least a part of the outer shell of the electric motor 1. Therefore, the radiator 30 radiates heat from the electric motor 1 into the air space.

[0054] The heat sink 30 has a base 31 and a plurality of heat sink fins 32 standing on the outer surface of the base 31 .

[0055] The base 31 is a base member (main body) of the heat sink 30. As shown in Fig. 3, the base 31 is provided so as to cover a second opening 82 provided in the molded resin 80. The base 31 closes the second opening 82.

[0056] The heat sink 30 not only functions as a heat sink, but also as a bracket that holds the second bearing 60. Specifically, the base 31 holds the second bearing 60. For this reason, a recess 31a that houses the second bearing 60 is provided on the inner surface of the base 31. The second bearing 60 is disposed in the recess 31a and fixed to the base 31.

[0057] As shown in Figure 3, the outer surface of the base 31 is dome-shaped. Specifically, the outer surface of the base 31 is dome-shaped and protrudes outward from the electric motor 1. In other words, the outer surface of the base 31 has a convex shape with the central portion protruding outward. The outer surface of the base 31 is spherical. Therefore, the outline of the outer surface of the base 31 in a cross-sectional view is an arc. The central portion of the outer surface of the base 31 is the most protruding portion of the outer surface of the base 31. The center of the outer surface of the base 31 is located on the axis C of the rotation shaft 21.

[0058] 2 and 4, each of the plurality of heat dissipation fins 32 is a plate-shaped material. The plurality of heat dissipation fins 32 are arranged so as to form a plurality of air passages extending from the center of the base 31 toward the outside. The plurality of air passages formed by the plurality of heat dissipation fins 32 are spaces (gaps) between two adjacent heat dissipation fins 32, and serve as flow paths through which air flows.

[0059] 4 , the plurality of air passages formed by the plurality of heat dissipation fins 32 extend from the center to the outer edge of the base 31. The plurality of air passages formed by the plurality of heat dissipation fins 32 are formed so as to straddle the center of the base 31. In other words, the plurality of heat dissipation fins 32 do not include any heat dissipation fins 32 formed so as to straddle the center of the base 31, and the plurality of heat dissipation fins 32 are formed in a shape that does not block the plurality of air passages at the center of the base 31.

[0060] 4 , when the outer surface of the base 31 is divided into N regions, the heat dissipation fins 32 are arranged parallel to one another in each of the N regions. Specifically, the outer surface of the base 31 is divided into the N regions along the circumferential direction. That is, each of the divided regions is fan-shaped. In each of the divided regions, the heat dissipation fins 32 are arranged parallel to one another.

[0061] In this embodiment, the outer surface of the base 31 is divided into three regions (N=3). Specifically, the outer surface of the base 31 is equally divided into three regions at 120° intervals. In each of the three regions, a plurality of heat dissipation fins 32 are provided parallel to one another. The plurality of heat dissipation fins 32 extend from the center of the base 31 outward.

[0062] The heat sink 30, which is a heat dissipation member, is preferably made of a material with high thermal conductivity, such as a metal material. For example, the heat sink 30 is preferably made of a metal material, such as aluminum or copper. In this embodiment, the heat sink 30 is made of an aluminum material containing aluminum as a main component. The base 31 and the heat dissipation fins 32 may be integrally molded. Alternatively, the base 31 and the heat dissipation fins 32 may be manufactured separately and then connected.

[0063] In the electric motor 1, when current is applied to the windings 12 of the stator 10, a field current flows through the windings 12, generating magnetic flux in the stator 10 (stator core 11). This generates magnetic flux that flows from the stator 10 toward the rotor 20. Specifically, magnetic flux is generated from each of the multiple teeth of the stator core 11 of the stator 10 toward the magnetic flux generating section 22 of the rotor 20. Meanwhile, in the rotor 20, magnetic flux that passes through the stator 10 is generated by the multiple permanent magnets 22a of the magnetic flux generating section 22. A magnetic force generated by the interaction between the magnetic flux generated in the stator 10 and the magnetic flux generated from the rotor 20 becomes a torque that rotates the rotor 20, and the rotor 20 rotates.

[0064] The electric motor 1 is used in, for example, an air conditioner or other air conditioner. Specifically, the electric motor 1 is mounted in an outdoor unit of the air conditioner as a fan motor having a rotary fan attached to a first portion 21a of a rotary shaft 21.

[0065] Next, the effects of the electric motor 1 according to the present embodiment will be described in comparison with an electric motor 1X of a comparative example using Figures 5 to 8. Figure 5 is a perspective view of the electric motor 1X of the comparative example as seen from the side opposite the output shaft. Figure 6 is a plan view of the electric motor 1X of the comparative example as seen from the side opposite the output shaft. Figure 7 is a half cross-sectional view of the electric motor 1X of the comparative example. Figure 8 is a diagram for explaining the effects of the electric motor 1 according to the embodiment. In Figure 8, thick arrows indicate the flow of air.

[0066] 5 to 7, like the electric motor 1 in the above embodiment, the electric motor 1X includes a radiator 30X having a base 31X and a plurality of radiating fins 32X standing on the base 31X. The electric motor 1X differs from the electric motor 1 in the above embodiment in the shapes of the base 31X and the radiating fins 32X.

[0067] 7, in the electric motor 1X, the outer surface of the base 31X is not dome-shaped but is flat. In other words, the outer surface of the base 31X is a plane including a perpendicular line intersecting with the axis C of the rotating shaft 21.

[0068] 5 and 6, in the electric motor 1X, the plurality of heat dissipation fins 32X extend radially from the center of the base 31X. In the electric motor 1X, the plurality of heat dissipation fins 32X include a heat dissipation fin 32aX that is formed in a cross shape so as to straddle the center of the base 31X.

[0069] In the electric motor 1X, not only is a bracket 70 provided on the output shaft side, but a bracket 90X is also provided on the opposite side of the output shaft. Therefore, the second bearing 60 is not held by the radiator 30X, but by the bracket 90X. The bracket 90X is provided so as to close the opening of the molded resin 80. The radiator 30X is disposed on the outer surface side of the bracket 90X.

[0070] As shown in Fig. 7, a rotary fan 2 is attached to the rotary shaft 21 of the electric motor 1X. When the electric motor 1X is operated to rotate the rotary fan 2, a flow of air (cooling air) is created by the rotation of the rotary fan 2, as shown by the thick arrow in Fig. 7. This air collides with the radiator 30X, thereby dissipating the heat of the electric motor 1X that has been conducted to the radiator 30X.

[0071] In this case, in the electric motor 1X, the outer surface of the base 31X is flat. As a result, the wind generated by the rotation of the rotary fan 2 collides perpendicularly with the outer surface of the base 31X. Therefore, when the wind generated by the rotation of the rotary fan 2 collides with the outer surface of the base 31X, it does not flow smoothly outward from the outer surface of the base 31X.

[0072] Moreover, in the electric motor 1X, the multiple heat dissipation fins 32X include a heat dissipation fin 32aX that is formed in a cross shape and straddles the center of the base 31X. Therefore, the flow of air generated by the rotation of the rotary fan 2 is blocked by the heat dissipation fin 32aX, resulting in stagnation of convection.

[0073] As a result, the heat sink 30X of the electric motor 1X cannot efficiently dissipate heat, making it difficult to sufficiently suppress the temperature rise of the electric motor 1X.

[0074] 8, in the heat sink 30 of the electric motor 1 according to this embodiment, the outer surface of the base 31 is dome-shaped. The plurality of heat dissipation fins 32 are provided so as to form a plurality of air passages extending from the center of the base 31 to the outside.

[0075] With this configuration, as shown in FIG. 8 , the rotary fan 2 is attached to the rotary shaft 21 of the electric motor 1, and the electric motor 1 is operated to rotate the rotary fan 2. As indicated by the bold arrows in FIG. 8 , the wind (cooling wind) generated by the rotation of the rotary fan 2 strikes the outer surface of the base 31. When the wind (cooling wind) strikes the outer surface of the base 31, the wind generated by the rotation of the rotary fan 2 flows smoothly along the surface of the base 31 toward the outer edge of the base 31. In other words, the base 31 having a dome-shaped outer surface can mitigate the wind's impact with the base 31 and increase the wind flow velocity on the surface of the base 31. In particular, in this embodiment, the outer surface of the base 31 is spherical, allowing the wind that reaches the outer surface of the base 31 to flow smoothly along the surface of the base 31 toward the outer edge. Moreover, the provision of multiple heat dissipation fins 32 that form multiple air passages from the center of the base 31 to the outside guides the wind from the center of the base 31 to the outside. This allows for a smooth airflow without stagnation of convection. In other words, stagnation of convection in the air path formed by the plurality of heat dissipation fins 32 is suppressed, and smooth convection can be generated from the center of the base 31 to the outer edge. Therefore, the heat sink 30 can provide an efficient heat dissipation effect. As a result, the temperature rise of the electric motor 1 can be sufficiently suppressed.

[0076] In particular, when a large current is passed through the motor 1 to obtain high output, the motor 1 may become hot, resulting in a deterioration in the performance of the motor 1. The motor 1 is provided with the heat sink 30 having the above-described configuration, and therefore, even when a large current is flowing, the heat generated by the motor 1 can be effectively dissipated. This makes it possible to prevent the performance of the motor 1 from being deteriorated due to a rise in the temperature of the motor 1. In other words, a motor 1 with high reliability against temperature can be realized.

[0077] Furthermore, in the electric motor 1 according to this embodiment, as described above (see FIG. 4), when the outer surface of the base 31 of the heat sink 30 is divided into N regions, the heat dissipation fins 32 are arranged parallel to each other in each of the regions.

[0078] This configuration allows the airflow to flow smoothly in each of the multiple regions, thereby improving the heat dissipation effect of the radiator 30. This further suppresses the temperature rise of the electric motor 1.

[0079] Furthermore, as shown in Figure 4, in this embodiment, when the heat sink 30 is viewed from the direction in which the rotation axis 21 extends, in each of the divided regions, the multiple heat sink fins 32 extend from the center of the base 31 outward.

[0080] This configuration allows air to flow smoothly from the center to the outer edges of the base 31 in each of the divided regions, thereby further improving the heat dissipation effect of the radiator 30. As a result, the temperature rise of the motor 1 can be further suppressed.

[0081] Furthermore, as shown in FIG. 8, in the electric motor 1 according to this embodiment, the heat-generating components mounted on the circuit board 40 are close to the inner surface of the base 31 .

[0082] With this configuration, heat generated by the heat-generating components can be conducted to the base 31 and dissipated efficiently. In this case, since the heat-generating components are in contact with the inner surface of the base 31, the heat generated by the heat-generating components can be conducted directly to the base 31. This allows for even more efficient dissipation of heat generated by the heat-generating components. The heat-generating components mounted on the circuit board 40 are, for example, semiconductor elements 41a such as IC packages. This allows for efficient dissipation of heat generated by the semiconductor elements 41a such as IC packages.

[0083] Furthermore, in the electric motor 1 according to this embodiment, the second bearing 60 is held by the heat sink 30. That is, the heat sink 30 also functions as a bracket that holds the second bearing 60. Specifically, the second bearing 60 is housed in a recess 31 a provided on the inner surface of the base 31 of the heat sink 30.

[0084] With this configuration, heat from the second bearing 60 can be directly conducted to the heat sink 30, thereby effectively dissipating the heat. In other words, the heat dissipation performance of the second bearing 60 can be improved. Furthermore, heat from the first bearing 50 can also be efficiently conducted to the heat sink 30 via the rotating shaft 21 connected to the second bearing 60. Therefore, the heat dissipation performance of the first bearing 50 can also be improved. Furthermore, heat from the magnetic flux generating unit 22 of the rotor 20 to which the rotating shaft 21 is attached can also be effectively dissipated. For example, heat from the permanent magnets 22a and core (rotor core) of the magnetic flux generating unit 22 can be dissipated.

[0085] In this way, by holding the second bearing 60 on the heat sink 30, not only is the heat dissipation of the semiconductor element 41a, such as an IC package, mounted on the circuit board 40 improved, but the heat dissipation of the other components (the second bearing 60, the first bearing 50, the permanent magnet 22a, the core, etc.) is also improved. As a result, it is possible to effectively suppress a decrease in performance and a decrease in lifespan of the electric motor 1 due to a rise in temperature.

[0086] Furthermore, in the electric motor 1 according to this embodiment, the base 31 of the heat radiator 30 is provided so as to cover the second opening 82 of the molded resin 80 .

[0087] This configuration eliminates the need to use a separate bracket 90X to close the second opening 82 of the molded resin 80, as in the electric motor 1X of the comparative example shown in Fig. 7. In addition, heat from the components (rotor 20, etc.) arranged inside the molded resin 80 can be effectively dissipated via the base 31.

[0088] Here, a thermal analysis was performed around the motor when an airflow was created by rotating the rotary fan 2 attached to the rotary shaft 21, and the results will be described using Figures 9A and 9B. Figure 9A is a diagram showing the heat distribution when the electric motor 1X of the comparative example shown in Figure 7 is used. Figure 9B is a diagram showing the heat distribution when the electric motor 1 according to the embodiment shown in Figure 8 is used.

[0089] As can be seen by comparing the temperature distribution on the surface of the base 31X of the heat sink 30X shown in Fig. 9A with the temperature distribution on the surface of the base 31 of the heat sink 30 shown in Fig. 9B, by using the electric motor 1 according to this embodiment, higher heat can be distributed near the surface of the base 31 in the dome-shaped portion of the base 31 (the portion where the flow rate is high). The fact that the heat near the surface of the base 31 is higher means that the heat of the electric motor 1 can be dissipated more efficiently. In this way, the electric motor 1 according to this embodiment can dissipate the heat of the electric motor 1 more efficiently than the electric motor 1X of the comparative example.

[0090] (Modification) The electric motor 1 according to the present disclosure has been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

[0091] For example, in the above embodiment, the outer surface of the base 31 of the heatsink 30 is spherical. However, the outer surface of the base 31 of the heatsink 30 is not limited to this. Fig. 10 is a half cross-sectional view of an electric motor 1A of a first modified example. Specifically, as in the electric motor 1A shown in Fig. 10, the outer surface of the base 31A of the heatsink 30A may be a conical surface. In this case, the base 31A has, for example, a conical portion. In the electric motor 1A shown in Fig. 10, the outer surface of the base 31A is also dome-shaped.

[0092] Fig. 11 is a half cross-sectional view of an electric motor 1B according to Modification 2. Alternatively, as in the electric motor 1B shown in Fig. 11, the outer surface of a base 31B of a heat sink 30B may be formed in a stepped shape. In the electric motor 1B shown in Fig. 11, the outer surface of the base 31B is also dome-shaped.

[0093] In the above embodiment, when the outer surface of the base 31 of the heat sink 30 is divided into N regions, the heat sink fins 32 are arranged parallel to each other in each of the divided regions. However, this is not limited to this. Fig. 12 is a plan view of the electric motor of Modification 3 as seen from the side opposite the output shaft. For example, as in the electric motor 1C shown in Fig. 12, the heat sink fins 32C of the heat sink 30C may extend in a spiral shape when viewed from the direction in which the rotating shaft 21 extends. In Fig. 12, the heat sink fins 32C also extend outward from the center of the base 31.

[0094] In the above embodiment, the electric motor 1 is described as being applied to a fan motor for an air conditioner. However, the present invention is not limited to this. For example, the electric motor 1 in the above embodiment can be used in various electric appliances such as household electric appliances and industrial electric appliances.

[0095] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would occur to those skilled in the art, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. Furthermore, the present disclosure also includes any combination of two or more claims from among the multiple claims set forth in the claims at the time of filing, within the scope of technical compatibility. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of technical compatibility, the present disclosure also includes all combinations of claims included in that multiple claim or multiple multiple multiple claims.

[0096] The electric motor according to the present disclosure can be widely used in devices equipped with an electric motor in various fields, including fan motors used in air conditioners and the like.

[0097] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1X Electric motor 2 Rotating fan 10 Stator 11 Stator core 12 Winding 13 Insulator 20 Rotor 21 Rotating shaft 21a First portion 21b Second portion 22 Magnetic flux generating portion 22a Permanent magnet 30, 30A, 30B, 30C, 30X Heat sink 31, 31A, 31B, 31X Base 31a Recess 32, 32aX, 32C, 32X Heat dissipation fin 40 Circuit board 41 Circuit component 41a Semiconductor element 50 First bearing 60 Second bearing 70, 90X Bracket 71 Recess 80 Molded resin 81 First opening 82 Second opening

Claims

1. An electric motor comprising: a rotor having a rotating shaft; a stator that generates a magnetic force acting on the rotor; and a heat sink located on the opposite side of the rotating shaft from the output shaft side and constituting at least a part of the outer shell of the electric motor, wherein the heat sink has a base and a plurality of heat sink fins standing on the outer surface of the base, the outer surface of the base is dome-shaped and protrudes outward from the outside of the electric motor, and the plurality of heat sink fins are arranged so as to form a plurality of air passages from the center of the base to the outside.

2. The electric motor according to claim 1, wherein when the outer surface of the base is divided into a plurality of regions, the plurality of heat dissipation fins are provided parallel to one another in each of the plurality of regions.

3. The electric motor according to claim 2, wherein, when viewed from the direction in which the rotation shaft extends, the plurality of heat dissipation fins extend outward from the center of the base in each of the plurality of regions.

4. The electric motor according to claim 1, wherein the heat dissipation fins extend in a spiral shape when viewed in the direction in which the rotating shaft extends.

5. The electric motor according to any one of claims 1 to 4, further comprising a bearing that supports the rotating shaft, and a recess that houses the bearing is provided on the inner surface of the base.

6. An electric motor according to any one of claims 1 to 4, wherein the stator is covered by a molded resin that forms part of the outer shell of the electric motor, the molded resin is formed to have an opening, the rotor is housed in the molded resin, and the base is provided to cover the opening of the molded resin.

7. The electric motor according to any one of claims 1 to 4, further comprising a circuit board on which a heat-generating component is mounted, said heat-generating component being located close to the inner surface of said base.

8. The electric motor according to claim 7, wherein the heat-generating component is a semiconductor element.

9. The electric motor according to claim 7, wherein the heat-generating component is in contact with the inner surface of the base.

10. An electric motor according to any one of claims 1 to 4, wherein the outer surface of the base is spherical.

11. The electric motor according to any one of claims 1 to 4, wherein the outer surface of the base is a conical surface.

12. The electric motor according to any one of claims 1 to 4, wherein the outer surface of the base is formed in a stepped shape.

Images