Electric motor

Abstract

This electric motor is provided with: a rotor having a rotating shaft that extends in the axial direction; a stator; and a bearing that rotatably supports the rotating shaft. The electric motor has two support parts of a first support part and a second support part as locations supported by a support base to which the electric motor is attached. The first support part and the second support part are present at mutually different positions in the axial direction in which the rotating shaft extends, and the positions of the first support part and the second support part are different from the positions of the bearings.

Description

electric motor

[0001] The present disclosure relates to electric motors.

[0002] 2. Description of the Related Art Electric motors are used in a variety of appliances, such as household electrical appliances and industrial electrical appliances. For example, a fan motor having a rotary fan attached to a rotating shaft is known as an electric motor used in an air conditioner.

[0003] A molded motor is sometimes used as the electric motor for a fan motor. A molded motor includes, for example, a stator covered with a molded resin, a rotor disposed inside the stator, two bearings that rotatably support the rotor's rotating shaft, and two brackets that each hold the two bearings (see Patent Document 1).

[0004] When an electric motor is installed in an apparatus such as an air conditioner, it is attached to a support base. In this case, the electric motor has a motor support portion, which is the portion supported by the support base. In order to prevent vibrations generated during operation of the electric motor from being transmitted to the outside of the electric motor, a structure has been proposed in which a ring-shaped vibration-isolating member is fitted into a bracket that holds the bearing, and this vibration-isolating member is supported by the support plate of the support base. In an electric motor with such a structure, the motor support portion, which is the portion supported by the support base, becomes part of the vibration-isolating member.

[0005] However, in conventional electric motors, the bracket that holds the bearing and the motor support part of the electric motor are located at the same position in the axial direction of the rotating shaft. In other words, the position of the bearing and the position of the motor support part are aligned in the axial direction of the rotating shaft. Therefore, if an external impact is applied while the electric motor supported on the support base is being transported by truck or the like, the external impact is directly applied to the bearing via the motor support part. As a result, dents (fretting) occur on the transfer surface of the bearing, which causes the problem of abnormal noise when the electric motor is operated.

[0006] JP 2018-93564 A

[0007] 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 absorb external shocks applied to bearings.

[0008] In order to achieve the above object, an electric motor according to one aspect of the present disclosure is an electric motor mounted on a support base, and comprises a rotor having a rotating shaft extending in the axial direction, a stator, and a bearing that rotatably supports the rotating shaft, and the electric motor has two support parts at which it is supported on the support base, and the two support parts are located at different positions in the axial direction, and the positions of the two support parts and the position of the bearing are different.

[0009] It is preferable that the stator is molded with molded resin, the electric motor has two vibration-damping members supported on the support base, one of the two vibration-damping members forming one of the two support parts, and the other of the two vibration-damping members forming the other of the two support parts.

[0010] The electric motor comprises two housing rings fixed to the molded resin, one of the two housing rings having one of the two vibration-damping members attached thereto and the other of the two housing rings having the other of the two vibration-damping members fixed thereto, and it is preferable that the material constituting the two housing rings is different from the material constituting the molded resin.

[0011] The rigidity of the two housing rings is preferably higher than the rigidity of the molding resin.

[0012] At least one of the two housing rings preferably has a cylindrical outer peripheral wall, at least a portion of which is fixed to the molding resin.

[0013] The bearing and the rotating shaft are in contact with each other at two holding portions, and when the distance between the two support portions in the axial direction is D and the distance between the two holding portions is d, it is preferable that the relationship D>d be satisfied.

[0014] In the axial direction, the two holding portions are preferably located between the two support portions.

[0015] The bearing is preferably a sliding bearing that supports the rotating shaft at two locations.

[0016] According to the present disclosure, it is possible to realize an electric motor that can absorb external impacts applied to bearings.

[0017] FIG. 1 is a perspective view of an electric motor according to an embodiment. FIG. 2 is an exploded perspective view of an electric motor according to an embodiment. FIG. 3 is a cross-sectional view of an electric motor according to an embodiment. FIG. 4 is a cross-sectional view of an electric motor according to an embodiment taken along line IV-IV in FIG. 3. FIG. 5 is a side view of an electric motor attached to a support base. FIG. 6 is a perspective view of an electric motor attached to a support base. FIG. 7 is a side view showing the configuration of an electric motor of a comparative example. FIG. 8 is a diagram showing the results of a hammering test performed on an electric motor according to an embodiment and an electric motor of a comparative example.

[0018] 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.

[0019] Each figure is a schematic diagram and is not necessarily an exact representation. Therefore, the scales and the like are not necessarily the same in each figure. In all figures, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0020] 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, for convenience, the direction in which the axis C of the rotating shaft 11 extends is defined as the up-down direction. However, this up-down direction may differ from the actual up-down direction depending on the usage state of the electric motor 1, etc. In this embodiment, the radial direction of the rotor 10 and the stator 20 is defined as the "radial direction," and the rotation direction of the rotor 10 is defined as the "circumferential direction." In other words, the direction perpendicular to the axis C of the rotating shaft 11 is defined as the "radial direction." The direction circumferentially around the axis C of the rotating shaft 11 is defined as the "circumferential direction." The direction in which the axis C of the rotating shaft 11 extends (the longitudinal direction of the rotating shaft 11) is defined as the "axial direction."

[0021] (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. Fig. 2 is an exploded perspective view of the electric motor 1 according to the embodiment. The rotating shaft 11 is omitted in Fig. 2. Fig. 3 is a cross-sectional view of the electric motor 1 according to the embodiment. Fig. 3 shows a cross-section taken along a plane passing through the rotating shaft 11. Fig. 4 is a cross-sectional view of the electric motor 1 according to the embodiment taken along line IV-IV in Fig. 3.

[0022] 1 to 3, the electric motor 1 includes a rotor 10 having a rotating shaft 11, a stator 20 molded with mold resin 30, a bearing 40 supporting the rotating shaft 11, a first housing ring 50, and a second housing ring 60. In this way, the electric motor 1 is a molded motor in which the stator 20 is covered with mold resin 30. The electric motor 1 is a brushless motor that does not use brushes.

[0023] The electric motor 1 further includes a vibration-isolating member 70 to prevent vibrations generated during operation of the electric motor 1 from being transmitted to the outside of the electric motor 1. The electric motor 1 further includes an oil recovery mechanism 80 for recovering oil contained in the bearings 40, which are oil-impregnated metal bearings.

[0024] 3 and 4, the electric motor 1 is an inner rotor type motor in which the rotor 10 is disposed inside the stator 20. In other words, the stator 20 is disposed so as to surround the rotor 10. The rotor 10 and the stator 20 are disposed with a gap therebetween.

[0025] The rotor 10 has a configuration in which a plurality of north and south poles are repeated around the circumference. The rotor 10 rotates due to the magnetic force generated by the stator 20. The rotor 10 rotates around the axis C of the rotating shaft 11.

[0026] The rotor 10 includes a rotating shaft 11, a magnet 12 that generates a magnetic force acting on the stator 20, and a frame 13 for fixing the magnet 12 to the rotating shaft 11. The rotor 10 is a coreless rotor that does not have a core (iron core).

[0027] The rotating shaft 11 is a shaft including an axis C. The rotating shaft 11 is a long, rod-shaped member. As an example, the rotating shaft 11 is a metal rod made of a metal material such as SUS (Stainless Used Steel). The axis C of the rotating shaft 11 serves as the center of rotation of the rotor 10. The longitudinal direction of the rotating shaft 11, i.e., the direction in which the rotating shaft 11 extends (extension direction), is sometimes referred to as the direction of the axis C.

[0028] One end of the rotating shaft 11 protrudes to the outside through the through hole of the first housing ring 50. The other end of the rotating shaft 11 protrudes to the outside through the through hole of the second housing ring 60. The portions of the rotating shaft 11 protruding from the first housing ring 50 and the second housing ring 60 can be used as the output shaft of the rotating shaft 11. In this embodiment, both ends of the rotating shaft 11 protrude from the first housing ring 50 and the second housing ring 60, respectively. However, only one end of the rotating shaft 11 may protrude from the first housing ring 50 or the second housing ring 60.

[0029] As shown in FIGS. 2 to 4 , the magnet 12 has a cylindrical shape. Specifically, the magnet 12 is a cylindrical permanent magnet. The magnet 12 may not be composed of a single magnet, but may be composed of multiple magnets. The magnet 12 is a rare earth magnet made of a rare earth element. The magnet 12 generates the main magnetic flux in the rotor 10. As shown in FIGS. 3 and 4 , the outer circumferential surface of the cylindrical magnet 12 is an air gap surface that ensures an air gap between the magnet 12 and the stator 20. The outer circumferential surface of the magnet 12 faces the stator core 21 of the stator 20. The magnet 12 is magnetized so that north and south poles alternate on the air gap surface with the stator 20 along the rotation direction of the rotating shaft 11. As an example, the magnet 12 is magnetized to have eight poles.

[0030] As shown in Fig. 3, the magnet 12 is fixed to the rotating shaft 11 via the frame 13. Specifically, the frame 13 to which the magnet 12 is attached is fixed to the rotating shaft 11. For example, the frame 13 is a metal frame made of a metal plate. The frame 13 is fixed to the rotating shaft 11 by press-fitting the rotating shaft 11 into a through-hole provided in the frame 13. The frame 13 can also be made of another material, such as a resin frame made of a resin material, as long as it can fix the magnet 12 to the rotating shaft 11.

[0031] 3 and 4, the stator 20 is disposed to face the rotor 10. The stator 20 generates a magnetic force acting on the rotor 10. The stator 20 is a field magnet. The stator 20 and the rotor 10 form a magnetic circuit.

[0032] The stator 20 is configured so that multiple north and south poles appear alternately along the circumferential direction to generate magnetic flux on the air gap surface with the magnet 12 of the rotor 10. The stator 20 is configured with an electromagnet. The stator 20 has a stator core 21 (iron core) and windings 22 attached to the stator core 21. The windings 22 are shown schematically in Figures 2 to 4.

[0033] The stator core 21 generates a magnetic force for rotating the rotor 10. The stator core 21 is a magnetic body made of a magnetic material. As an example, the stator core 21 is a laminated body in which a plurality of electromagnetic steel sheets formed into a predetermined shape are stacked in the direction in which the axis C of the rotating shaft 11 extends (axial direction). The stator core 21 is not limited to a laminated body of electromagnetic steel sheets. The stator core 21 may also be a bulk body made of a magnetic material. As shown in FIGS. 3 and 4 , a small air gap exists between the inner circumferential surface of the stator core 21 and the magnet 12 of the rotor 10.

[0034] As shown in FIG. 4 , the stator core 21 has a plurality of teeth 21 a that generate a main magnetic flux. Each of the plurality of teeth 21 a is a magnetic pole tooth. Each of the plurality of teeth 21 a generates a magnetic force when current is passed through the winding 22. The plurality of teeth 21 a are formed to protrude inward in the radial direction, which is a direction perpendicular to the axis C of the rotating shaft 11. In other words, the plurality of teeth 21 a protrude toward the rotating shaft 11. The plurality of teeth 21 a are arranged at equal intervals along the circumferential direction, with slots formed between two adjacent teeth 21 a. The stator core 21 is provided with 12 teeth 21 a. In other words, the stator 20 has 12 slots.

[0035] The windings 22 are winding coils wound around the teeth 21 a of the stator core 21 via insulators. The windings 22 are wound around the stator core 21 so that a magnetic force acting on the magnets 12 of the rotor 10 is generated when a current flows through them. The windings 22 are, for example, concentrated windings wound around each tooth 21 a via insulators. The windings 22 are housed in slots in the stator core 21. The electric wires constituting the windings 22 are, for example, insulating coated wires. The electric wires constituting the windings 22 have a core conductive wire made of a conductive material such as copper or aluminum, and an insulating film coating the conductive wire. The insulator (not shown) is made of an insulating resin material or the like. The insulator is disposed between the windings 22 and the stator core 21.

[0036] When current is applied to the windings 22, a magnetic force is generated from each of the multiple teeth 21a. For example, the multiple windings 22 are electrically connected as a three-phase winding so that the rotor 10 rotates as a three-phase synchronous motor. In this case, the multiple windings 22 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 22 attached to each tooth 21a are energized and 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 in each tooth 21a.

[0037] 1 to 4, the stator 20 is a molded stator covered with a molded resin 30. The molded resin 30 covers the outer portion of the stator 20 over the entire circumferential direction of the stator 20. Specifically, the molded resin 30 covers the outer portions of the stator core 21 and the windings 22.

[0038] 2 and 3 , the molded resin 30 that covers the stator 20 constitutes a housing that encloses the rotor 10. The molded resin 30 is formed in a cylindrical shape with a bottom. The molded resin 30 constitutes the outer shell of the electric motor 1.

[0039] The mold resin 30 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The mold resin 30 is made of a thermosetting resin. The mold resin 30 is made of unsaturated polyester, which is a thermosetting resin. Specifically, the mold resin 30 is made of a white BMC (Bulk Molding Compound) unsaturated polyester resin.

[0040] Although not shown, a circuit board to which the windings 22 of the stator 20 are connected may be embedded in the molded resin 30. In this case, the ends of the windings 22 for each phase are connected at winding connection portions on the circuit board. For example, the circuit board is formed with pattern wiring for electrically connecting the plurality of windings 22 for each of the U, V, and W phases. The ends of the windings 22 for each phase are electrically connected to the pattern wiring on the circuit board by solder or the like.

[0041] The bearing 40 rotatably supports the rotating shaft 11. As shown in FIG. 3 , the rotating shaft 11 passes through the bearing 40. The bearing 40 is a sliding bearing. Specifically, the bearing 40 is an oil-impregnated metal bearing. The bearing 40 is made of sintered metal impregnated with lubricating oil. More specifically, the bearing 40 is an impregnated metal bearing in which sintered metal is impregnated with lubricating oil. The sintered metal that makes up the bearing 40 is, for example, a sintered body formed by molding and sintering metal powder. In this embodiment, the bearing 40 is a cylindrical sleeve metal bearing.

[0042] The bearing 40 and the rotating shaft 11 are in contact with each other at two retaining portions 42 and 43. Specifically, as shown in FIG. 3 , the bearing 40 and the rotating shaft 11 are in contact with each other at two locations: a first inner circumferential line P1 (a first outer circumferential line of the rotating shaft 11) and a second inner circumferential line P2 (a second outer circumferential line of the rotating shaft 11) along the inner circumferential direction of the bearing 40. The bearing 40 and the rotating shaft 11 are in surface contact with each other at two locations: a first inner circumferential surface R1 (a first outer circumferential surface of the rotating shaft 11) of the bearing 40, which is an area including the first inner circumferential line P1, and a second inner circumferential surface R2 (a second outer circumferential surface of the rotating shaft 11) of the bearing 40, which is an area including the second inner circumferential line P2. The first inner circumferential line P1 is located at the upper end of the bearing 40 in the axial direction of the rotating shaft 11. The second inner circumferential line P2 is located at the lower end of the bearing 40. Therefore, the first inner circumferential surface R1 is located at the upper end of the bearing 40. The second inner peripheral surface R2 is located at the lower end of the bearing 40. The upper end of the bearing 40 is the central portion of the rotating shaft 11. The lower end of the bearing 40 is the portion of the rotating shaft 11 where the first housing ring 50 is disposed.

[0043] There is only one bearing 40. In other words, the rotating shaft 11 is supported by one bearing 40. Therefore, one bearing 40 supports the rotating shaft 11 at two locations.

[0044] As shown in FIG. 3 , the first housing ring 50 and the second housing ring 60 are fixed to the molded resin 30. The materials constituting the first housing ring 50 and the second housing ring 60 are different from the material constituting the molded resin 30. The rigidity of both the first housing ring 50 and the second housing ring 60 is higher than the rigidity of the molded resin 30. In other words, the first housing ring 50 and the second housing ring 60 have a higher Young's modulus than the molded resin 30 and are therefore harder. In this embodiment, the first housing ring 50 and the second housing ring 60 are made of a metal material such as iron. For example, the first housing ring 50 and the second housing ring 60 are formed into a predetermined shape by pressing a metal plate of a uniform thickness.

[0045] The first housing ring 50 has a protruding portion 51 that protrudes outward and a cylindrical outer peripheral wall 52. The protruding portion 51 is formed in a cylindrical shape with a bottom so as to protrude to one side in the axial direction of the rotating shaft 11. The outer peripheral wall 52 is also cylindrical. The diameter of the outer peripheral wall 52 is larger than the diameter of the protruding portion 51. At least a portion of the outer peripheral wall 52 is fixed to the molded resin 30. In this embodiment, the entire outer peripheral wall 52 is embedded in the molded resin 30.

[0046] The second housing ring 60 has a protruding portion 61 that protrudes outward and a lid portion 62 that covers an opening in the molded resin 30. Specifically, the protruding portion 61 is formed in a cylindrical shape with a bottom so as to protrude to the other side in the axial direction of the rotating shaft 11. Specifically, the protruding portion 61 is made up of two cylinders with different diameters.

[0047] The first housing ring 50 and the second housing ring 60 are dummy brackets that do not hold the bearings 40. As will be described later, the bearings 40 are held by a holder 84.

[0048] Vibration-isolating members 70 are attached to each of the first housing ring 50 and the second housing ring 60. One of the two vibration-isolating members 70 is fitted into the protruding portion 51 of the first housing ring 50. The other of the two vibration-isolating members 70 is fitted into the protruding portion 61 of the second housing ring 60. The vibration-isolating members 70 are supported by a support base that supports the electric motor 1.

[0049] The vibration-isolating member 70 is a vibration-isolating device that suppresses the transmission of vibrations generated in the electric motor 1 during operation of the electric motor 1 to the outside of the electric motor 1. As shown in Figures 1 to 3, the vibration-isolating member 70 is an annular vibration-isolating ring. Specifically, the vibration-isolating member 70 has an overall annular (Baumkuchen-like) shape that is thin in the axial direction and wide in the radial direction.

[0050] 2 and 3, the vibration-isolating member 70 includes a rubber material 71 that is an elastic body, and a metal ring 72 that covers the outer peripheral surface of the rubber material 71. The center of the vibration-isolating member 70 coincides with the axis C of the rotating shaft 11 of the electric motor 1.

[0051] The rubber material 71 is an elastic body (elastic rubber) having elasticity. That is, the rubber material 71 has rubber elasticity. The material of the rubber material 71 can be an elastomer resin, a silicone resin, or the like.

[0052] The rubber material 71 has an annular shape. Specifically, the rubber material 71 has an overall thin annular shape (Baumkuchen-like) that is wide in the radial direction. Therefore, an opening 71a is formed in the center of the rubber material 71. The two vibration-damping members 70 can be attached to the first housing ring 50 and the second housing ring 60 by fitting the openings 71a of each of the two vibration-damping members 70 into the protruding portions 51 of the first housing ring 50 and the protruding portions 61 of the second housing ring 60, respectively. The openings 71a have a circular shape in a plan view. The opening diameters of the openings 71a of each of the two vibration-damping members 70 are the same as or slightly smaller than the diameters of the protruding portions 51 and 61, respectively. The planar shape of the openings 71a of each of the two vibration-damping members 70 is not limited to a circular shape, and may be any shape that fits into the protruding portions 51 and 61, respectively.

[0053] The metal ring 72 covers the outer peripheral surface of the rubber material 71. In this embodiment, the metal ring 72 is in contact with the outer peripheral surface of the rubber material 71. The metal ring 72 is an outer peripheral ring that forms the outer shell of the vibration-damping member 70. The metal ring 72 is an annular ring. The metal ring 72 is formed by bending a thin, long metal plate. The metal ring 72 can be made of, for example, an iron-based metal material. The width of the metal ring 72 is the same as or slightly smaller than the width of the rubber material 71.

[0054] The metal ring 72 has a groove formed around the entire circumference of the metal ring 72. The groove can be formed by applying concave and convex press processing to the metal plate that constitutes the metal ring 72. By forming a concave groove in the metal plate that constitutes the metal ring 72, a convex rib that protrudes toward the rubber material 71 is formed on the metal plate in correspondence with the groove. The rib of the metal ring 72 forms a concave groove on the outer peripheral surface of the rubber material 71.

[0055] The oil recovery mechanism 80 is a mechanism for recovering lubricating oil (lubricating oil) contained in the oil-impregnated metal bearing 40. As shown in Figures 2 and 3, the oil recovery mechanism 80 includes a slinger 81, a felt 82, a washer 83, and a holder 84.

[0056] The slinger 81 is fixed to the rotating shaft 11. Therefore, the slinger 81 rotates together with the rotating shaft 11. The slinger 81 is fixed to the rotating shaft 11 by being press-fitted into the rotating shaft 11. The slinger 81 is fixed to the rotating shaft 11 so as to face the bearing 40. The slinger 81 not only has the function of preventing the lubricating oil that has flowed out of the bearing 40 from leaking out of the slinger 81, but also has the function of recovering the lubricating oil that has flowed out of the bearing 40 and returning it to the bearing 40. The slinger 81 is made of, for example, a resin material.

[0057] The felt 82 is an example of an oil adsorbent member that absorbs the lubricating oil used in the bearing 40. The felt 82 is arranged so as to surround the outer periphery of the bearing 40. Specifically, the felt 82 has a cylindrical shape.

[0058] The washer 83 is inserted in a portion of the rotating shaft 11 between the bearing 40 and the slinger 81. Specifically, the washer 83 is provided between the open end face of the bearing 40 and the slinger 81. The washer 83 is a thrust washer. The washer 83 supports the slinger 81, which rotates together with the rotating shaft 11. In other words, the washer 83 absorbs the rotational motion of the slinger 81 while absorbing the load generated in the longitudinal direction (thrust direction) of the rotating shaft 11. In this way, by inserting the washer 83 between the bearing 40 and the slinger 81, it is possible to suppress end surface friction between the bearing 40 and the slinger 81. Multiple washers 83 are inserted between the bearing 40 and the slinger 81. This effectively suppresses the relative rotational speed of the slinger 81 with respect to the bearing 40. The washer 83 is made of, for example, a resin material.

[0059] The holder 84 houses the bearing 40. The holder 84 houses not only the bearing 40 but also the slinger 81, the felt 82, and the washer 83. The holder 84 is formed in a cylindrical shape with a bottom. The holder 84 has a first holder portion that is a cylinder with a small inner diameter and a second holder portion that is a cylinder with a large inner diameter. The bearing 40 is present across the first holder portion and the second holder portion. Meanwhile, the slinger 81, the felt 82, and the washer 83 are housed in the second holder portion of the holder 84. The holder 84 may be made of a metal material or a resin material. In this embodiment, the holder 84 is a metal holder made of metal. The holder 84 is fixed to the molded resin 30.

[0060] The electric motor 1 configured as described above is used, for example, as a fan motor mounted in an outdoor unit of an air conditioner. When the electric motor 1 is used as a fan motor, a rotary fan is attached to the rotary shaft 11 of the electric motor 1.

[0061] When installing the electric motor 1 in equipment such as an outdoor unit of an air conditioner, the electric motor 1 is attached to a support base 100, for example, as shown in Figures 5 and 6. Figure 5 is a side view of the electric motor 1 attached to the support base 100. Figure 6 is a perspective view of the electric motor 1 attached to the support base 100.

[0062] 5 and 6 , the electric motor 1 is supported on the support base 100 via vibration-isolating members 70 attached to the electric motor 1. Two vibration-isolating members 70 are attached to the electric motor 1. Therefore, the electric motor 1 is fixed to the support base 100 via the two vibration-isolating members 70.

[0063] The support base 100 is a base that supports the electric motor 1. The support base 100 is formed into a predetermined shape, for example, by pressing a metal plate. In this embodiment, the support base 100 is bent so that its cross section has a U-shape. The support base 100 has a bottom plate portion and a pair of side plate portions (support plates) that stand upright from the ends of the bottom plate portion. The support base 100 is, for example, a steel plate. However, the support base 100 is not limited to this.

[0064] As shown in Figures 5 and 6, the support base 100 has a motor receiving portion 110 as a portion to which the electric motor 1 is attached. In this embodiment, the motor receiving portion 110 is a pair of side plate portions (support plates) of the support base 100. A vibration-isolating member 70 of the electric motor 1 is placed on the motor receiving portion 110. In this case, the motor receiving portion 110 is an edge of a metal plate that constitutes the support base 100. Specifically, the motor receiving portion 110 is an arcuate edge formed by cutting out a portion of a side plate portion of the support base 100 in an arcuate shape. When the electric motor 1 is set on the support base 100, as shown in Figure 5, the groove of the metal ring 72 of the vibration-isolating member 70 of the electric motor 1 is fitted into the motor receiving portion 110.

[0065] The electric motor 1, with the vibration-isolating member 70 placed on the motor receiving portion 110 of the support base 100, is fixed to the support base 100 by fastening the vibration-isolating member 70 with the fastening member 200. Specifically, the vibration-isolating member 70 is compressed and deformed by fastening the metal ring 72 of the vibration-isolating member 70 with the fastening member 200. This allows the electric motor 1 to be fixed to the support base 100.

[0066] The fastening member 200 is made up of a metal band 210 made of steel plate and a screw 220. In this case, the electric motor 1 can be fixed to the support base 100 as follows.

[0067] First, the electric motor 1 is set on the support base 100 so that the vibration-isolating member 70 is placed on the motor support portion 110. Specifically, the grooves of the metal ring 72 of the vibration-isolating member 70 are fitted into the motor support portion 110 of the support base 100, and the electric motor 1 is set on the support base 100. Next, the locking holes 211 of the metal band 210 are engaged with the locking pieces 120 of the support base 100, and the metal band 210 is placed over the vibration-isolating member 70. Thereafter, the metal band 210 is tightened with the screws 220. This tightens the metal ring 72 of the vibration-isolating member 70 with the metal band 210. This causes the metal ring 72 to tighten the rubber material 71. As a result, the vibration-isolating member 70 is compressed and fixed to the motor support portion 110. In this manner, the electric motor 1 can be fixed to the support base 100 via the vibration-isolating member 70. The screws 220 are bolts or screws. If the screw 220 is a bolt, the metal band 210 may be fastened with a bolt and a nut.

[0068] As shown in Fig. 5 , the electric motor 1 attached to the support base 100 in this manner has two support portions (motor support portions), a first support portion S1 and a second support portion S2, as locations supported by the support base 100. The first support portion S1 and the second support portion S2 are portions that contact the support base 100. In this embodiment, the electric motor 1 contacts the motor support portion 110 (the tip of the support plate) of the support base 100. Therefore, the first support portion S1 and the second support portion S2 contact the motor support portion 110.

[0069] The two points of contact between the motor 1 and the support base 100 may be point contact, line contact, or surface contact. In other words, the first support portion S1 and the second support portion S2 may be any of a point, a line, and a surface.

[0070] Two vibration-isolating members 70 are attached to the electric motor 1. The electric motor 1 is supported on the support base 100 via the two vibration-isolating members 70. Therefore, one of the two vibration-isolating members 70 has a first support portion S1, and the other of the two vibration-isolating members 70 has a second support portion S2. In other words, the first support portion S1 and the second support portion S2 are the points of contact between the vibration-isolating members 70 and the support base 100.

[0071] The first support portion S1 and the second support portion S2 are located at different positions in the axial direction of the rotating shaft 11. In other words, as shown in Fig. 5, if the intersections of perpendicular lines drawn from the first support portion S1 and the second support portion S2 toward the axial center C of the rotating shaft 11 with the axial center C of the rotating shaft 11 are defined as a first point a1 and a second point a2, respectively, the first point a1 and the second point a2 are located at different positions on the axial center C of the rotating shaft 11.

[0072] Furthermore, in the axial direction in which the rotating shaft 11 extends, the positions of the first support portion S1 and the second support portion S2 are different from the position of the bearing 40. Specifically, the positions of the first support portion S1 and the second support portion S2 are different from the positions of the first inner circumferential line P1 and the second inner circumferential line P2, which are two points where the bearing 40 and the rotating shaft 11 contact each other. That is, a first point a1 corresponding to the first support portion S1 is different from the positions of the first inner circumferential line P1 and the second inner circumferential line P2. A second point a2 corresponding to the second support portion S2 is different from the positions of the first inner circumferential line P1 and the second inner circumferential line P2. That is, in the direction perpendicular to the rotating shaft 11, the first support portion S1 and the second support portion S2 do not overlap with either the first inner circumferential line P1 or the second inner circumferential line P2.

[0073] In this embodiment, the positions of the first support portion S1 and the second support portion S2 are different from the positions of the first inner circumferential surface R1 and the second inner circumferential surface R2 in the axial direction of the rotation shaft 11. In other words, the first support portion S1 and the second support portion S2 do not overlap with either the first inner circumferential surface R1 or the second inner circumferential surface R2 in the direction perpendicular to the rotation shaft 11.

[0074] As shown in FIG. 5, in the axial direction in which the rotating shaft 11 extends, when the distance between the first support portion S1 and the second support portion S2 is D and the distance between the first inner circumferential line P1 and the second inner circumferential line P2, which are the two points where the bearing 40 and the rotating shaft 11 contact each other, is d, the relationship D>d is satisfied.

[0075] The first inner circumferential line P1 and the second inner circumferential line P2, which are two points where the bearing 40 and the rotating shaft 11 contact, are located between the first support portion S1 and the second support portion S2 in the axial direction of the rotating shaft 11. That is, the first point a1 corresponding to the first support portion S1 is located between the first support portion S1 and the second support portion S2. The second point a2 corresponding to the second support portion S2 is located between the first support portion S1 and the second support portion S2.

[0076] The effects of the electric motor 1 according to this embodiment will be described in comparison with an electric motor 1X of a comparative example. Fig. 7 is a side view showing the configuration of the electric motor 1X of the comparative example.

[0077] The electric motor 1X of the comparative example is a molded motor. As shown in FIG. 7 , the stator of the electric motor 1X of the comparative example is covered with molded resin 30. In the electric motor 1X of the comparative example, the rotating shaft 11 of the rotor 10 is supported by two bearings 40X. One of the two bearings 40X is held by a bracket 50X fixed to one side of the molded resin 30. The other of the two bearings 40X is held by a bracket 60X fixed to the other side of the molded resin 30. The electric motor 1X of the comparative example has vibration-damping members 70 fitted into each of the protrusions 51X of the bracket 50X and the protrusions 61X of the bracket 60X.

[0078] 5 and 6, the vibration-isolating member 70 is supported by the motor support portion 110, which is the support plate of the support base 100. Therefore, in the electric motor 1X of the comparative example, the two motor support portions, the first support portion S1 and the second support portion S2, which are the portions supported by the support base 100, are the contact portions between the vibration-isolating member 70 and the motor support portion 110 (the tip of the support plate).

[0079] In the electric motor 1X of the comparative example, the brackets 50X and 60X that hold the bearing 40X and the two locations (motor support portions) where the electric motor 1X is supported on the support base 100 are located at the same position in the axial direction of the rotating shaft 11. Therefore, the positions of the first inner circumferential line P1 and the second inner circumferential line P2, which are the two locations where the bearing 40X and the rotating shaft 11 come into contact, coincide with the positions of the first support portion S1 and the second support portion S2, which are the motor support portions where the electric motor 1X is supported on the support base 100, in the axial direction in which the rotating shaft 11 extends. In other words, in the axial direction in which the rotating shaft 11 extends, the position of the first inner circumferential line P1 coincides with the position of the first support portion S1, and the position of the second inner circumferential line P2 coincides with the position of the second support portion S2.

[0080] In the electric motor 1X of the comparative example configured in this manner, if an external impact is applied while the electric motor 1X supported on the support base 100 is being transported by truck or the like, the external impact is applied directly to the bearing 40X via the first support portion S1 and the second support portion S2 (motor support portion). As a result, in the electric motor 1X of the comparative example, dents (fretting) occur on the transfer surface of the bearing 40X, and abnormal noise is generated when the electric motor 1X is operated.

[0081] Here, in order to investigate the influence of an external impact on the electric motor 1 according to the present embodiment and the electric motor 1X of the comparative example, a hammering test was carried out using the electric motor 1 according to the present embodiment and the electric motor 1X of the comparative example. The results are shown in Fig. 8. Fig. 8 is a diagram showing the results of the hammering test carried out on the electric motor 1 according to the embodiment and the electric motor 1X of the comparative example.

[0082] As shown in Figure 8, in this test, for both the electric motor alone and the electric motor mounted on a support base, impacts were applied to predetermined locations with a hammer and frequency characteristics were measured using a pickup sensor. Specifically, for the electric motor alone, impacts were applied to the vibration-isolating member (impact point A) and the center portion of the molded resin (impact point B), and frequency characteristics were measured for each of impact points A and B. For the electric motor mounted on a support base, impacts were applied to the center portion of the side surface of the support base (impact point C) and the support plate of the support base (impact point D), and frequency characteristics were measured for each of impact points C and D. In the electric motor 1 according to this embodiment ("Example" in Figure 8), the bearing 40 was an oil-impregnated metal bearing, and in the electric motor 1X of the comparative example ("Comparative Example" in Figure 8), the bearing 40X was a ball bearing. A pickup sensor was placed on one end of the rotating shaft to measure frequency characteristics.

[0083] As a result, it was found that for the comparative example electric motor 1X, there are two natural frequencies near 300 Hz and near 700 Hz for all of the impact points A to D. The natural frequency near 300 Hz is presumed to be a resonance of the rotor. The natural frequency near 700 Hz is presumed to be a resonance of bearing 40X (ball bearing).

[0084] On the other hand, for the electric motor 1 according to this embodiment, although a natural frequency exists near 300 Hz at all of the impact points A to D, the level is very small, and no natural frequency exists near 700 Hz. The electric motor 1 according to this embodiment has a lower gain than the electric motor 1X of the comparative example at all of the impact points A to D, demonstrating high reliability with respect to external vibrations and vibrations due to the natural frequency of the electric motor itself. In other words, it was found that the electric motor 1 according to this embodiment can mitigate external impacts applied to the bearings. It was also found that using vibration-damping materials when mounting the electric motor on a support base can achieve vibration reduction and vibration absorption effects at frequencies above 400 to 500 Hz.

[0085] As described above, the electric motor 1 according to this embodiment has two support portions, the first support portion S1 and the second support portion S2, as locations supported by the support base 100. In the electric motor 1, the first support portion S1 and the second support portion S2 are located at different positions in the axial direction of the rotating shaft 11, and the positions of the first support portion S1 and the second support portion S2 are different from the position of the bearing 40.

[0086] With this configuration, even if the electric motor 1 is subjected to an external impact during transportation, etc., the external impact can be prevented from being directly transmitted to the bearing 40. This reduces the external impact applied to the bearing 40. Therefore, damage to the bearing 40, such as dents (fretting) occurring on the transfer surface of the bearing 40, can be prevented. Therefore, the generation of abnormal noise during operation of the electric motor 1 can be prevented. As a result, an electric motor 1 can be obtained that is quiet and highly reliable.

[0087] Moreover, it is possible to efficiently attenuate external impacts applied to the bearing 40. Therefore, the electric motor 1 can be held and fixed with a simpler support member (such as the vibration-isolating member 70), thereby making it possible to obtain an inexpensive electric motor 1.

[0088] Moreover, the electric motor 1 according to this embodiment is supported on the support base 100 via two vibration-isolating members 70. That is, one of the two vibration-isolating members 70 is the first support portion S1, and the other of the two vibration-isolating members 70 is the second support portion S2.

[0089] In this way, by attaching the electric motor 1 to the support base 100 via the two vibration-isolating members 70, it is possible to prevent external shocks from being transmitted to the electric motor 1 when they are applied to the support base 100. This further prevents damage to the bearings 40. Furthermore, by attaching the electric motor 1 to the support base 100 via the two vibration-isolating members 70, it is also possible to prevent vibrations generated during operation of the electric motor 1 from being transmitted to the outside of the electric motor 1. Furthermore, it is possible to realize an electric motor 1 with low noise.

[0090] The electric motor 1 according to this embodiment also includes a first housing ring 50 and a second housing ring 60 fixed to the molded resin 30. A vibration-isolating member 70 is attached to each of the first housing ring 50 and the second housing ring 60. The first housing ring 50 and the second housing ring 60 are made of a different material from the material making up the molded resin 30.

[0091] This configuration can attenuate external shocks transmitted to the electric motor 1 via the vibration-damping member 70. Therefore, external shocks applied to the bearing 40 can be further alleviated. Furthermore, vibrations of the electric motor 1 can be attenuated when they are transmitted to the outside. Therefore, transmission of vibrations of the electric motor 1 to the outside can be further suppressed.

[0092] In this case, it is preferable that the rigidity of the first housing ring 50 and the second housing ring 60 is higher than the rigidity of the mold resin 30 .

[0093] This configuration allows external impacts to be efficiently attenuated, thereby effectively preventing external impacts from being applied to the bearing 40 and more efficiently attenuating vibrations of the electric motor 1 that are transmitted to the outside.

[0094] In the electric motor 1 according to this embodiment, the first housing ring 50 has a cylindrical outer peripheral wall 52. At least a portion of the outer peripheral wall 52 is embedded in the mold resin 30.

[0095] With this configuration, vibrations caused by external shocks can be damped by the first housing ring 50. Therefore, transmission of external shocks to the bearing 40 can be further suppressed. The second housing ring 60, instead of the first housing ring 50, may have an outer circumferential wall embedded in the molded resin 30. Furthermore, both the first housing ring 50 and the second housing ring 60 may have outer circumferential walls embedded in the molded resin 30.

[0096] In the electric motor 1 according to this embodiment, the bearing 40 and the rotating shaft 11 are in contact with each other at two holding portions 42, 43 on the first inner circumferential line P1 and the second inner circumferential line P2. In the axial direction of the rotating shaft 11, when the distance between the first support portion S1 and the second support portion S2 is D and the distance between the first inner circumferential line P1 and the second inner circumferential line P2 is d, the relationship D>d is satisfied.

[0097] This configuration can effectively prevent external impacts from being transmitted to the bearing 40. Therefore, damage to the bearing 40 due to external impacts can be further prevented.

[0098] In addition, in the electric motor 1 according to this embodiment, the first inner circumferential line P1 and the second inner circumferential line P2 exist between the first support portion S1 and the second support portion S2 in the axial direction in which the rotating shaft 11 extends.

[0099] With this configuration, even if the positions of the first support portion S1 and the second support portion S2 in the axial direction in which the rotating shaft 11 extends are different from the position of the bearing 40, it is possible to prevent the overall length of the electric motor 1 in the axial direction in which the rotating shaft 11 extends from becoming longer. As a result, even if the positions of the first support portion S1 and the second support portion S2 in the axial direction in which the rotating shaft 11 extends are different from the position of the bearing 40, it is possible to prevent the electric motor 1 from becoming larger. Therefore, a compact electric motor 1 can be realized.

[0100] Furthermore, in the electric motor 1 according to this embodiment, each bearing 40 is a sliding bearing that supports two locations of the rotating shaft 11. Specifically, the bearing 40 is an oil-impregnated metal bearing.

[0101] With this configuration, even if the positions of the first support portion S1 and the second support portion S2 in the axial direction in which the rotating shaft 11 extends are made different from the position of the bearing 40, it is possible to prevent the overall length of the electric motor 1 in the axial direction of the rotating shaft 11 from increasing. This makes it possible to prevent the electric motor 1 from becoming larger.

[0102] (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.

[0103] For example, in the above embodiment, when the distance between the first support portion S1 and the second support portion S2 is D and the distance between the first inner circumferential line P1 and the second inner circumferential line P2 is d, the relationship D>d is satisfied. However, this is not limited to this. Specifically, D≦d may be satisfied. With this configuration, the rotating shaft 11 can be stably held by the bearing 40.

[0104] Furthermore, in the above embodiment, the first inner circumferential line P1 and the second inner circumferential line P2, which include the two retaining portions 42, 43 where the bearing 40 and the rotating shaft 11 come into contact, are located between the first support portion S1 and the second support portion S2 in the axial direction of the rotating shaft 11. However, this is not limited to this. Specifically, only one of the first inner circumferential line P1 and the second inner circumferential line P2 may be located between the first support portion S1 and the second support portion S2 in the axial direction of the rotating shaft 11. In this case, it is also preferable that the relationship D>d is satisfied. However, this is not limited to this.

[0105] In the above embodiment, only one bearing 40 supports the holding portions 42, 43 of the rotating shaft 11 at two locations. However, this is not limited to this. Specifically, the rotating shaft 11 may be supported at two locations by two bearings. Even in this case, the first support portion S1 and the second support portion S2 are located at different positions in the axial direction of the rotating shaft 11, and the positions of the first support portion S1 and the second support portion S2 are different from the positions of the two bearings. Note that when two bearings are used, the bearings may be ball bearings instead of oil-impregnated metal bearings. In this case, the first housing ring 50 and the second housing ring 60 can be used as brackets to hold the ball bearings in the first housing ring 50 and the second housing ring 60, respectively.

[0106] In the above embodiment, the rotor 10 has eight poles. However, this is not a limitation. In the above embodiment, the stator 20 has twelve slots. However, this is not a limitation. Any number of poles can be applied to the rotor 10 and the stator 20.

[0107] Furthermore, in the above embodiment, the rotor 10 is a coreless rotor that does not have a core. However, this is not limiting. The rotor 10 may also be a rotor that has a rotor core. In this case, the rotor 10 may be an interior permanent magnet (IPM) rotor in which multiple permanent magnets are embedded in the core, or a surface permanent magnet (SPM) rotor in which multiple permanent magnets are provided on the outer surface of the core. The rotor 10 may also be an armature configured with a core and windings instead of using magnets.

[0108] In the above embodiment, the windings 22 of the stator 20 are wound around the stator core 21 in a concentrated winding manner. However, this is not limiting. For example, the windings 22 of the stator 20 may be wound around the stator core 21 in a distributed winding manner.

[0109] In the above embodiment, the electric motor 1 is a molded motor. However, this is not limiting. The technology of the present disclosure can be applied to motors other than molded motors. In other words, the technology of the present disclosure can be applied to motors in which the stator 20 is not covered with the mold resin 30.

[0110] In the above embodiment, the electric motor 1 is a brushless motor, but this is not limiting. The technology of the present disclosure can also be applied to a brushed motor that uses brushes.

[0111] 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.

[0112] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments and variations 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. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. 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 the technical contradiction, the present disclosure also includes any combination of all claims included in that multiple claim or multiple multiple claims.

[0113] The electric motor according to the present disclosure can be widely used in various electric appliances such as household electric appliances and industrial electric appliances.

[0114] REFERENCE SIGNS LIST 1 electric motor 10 rotor 11 rotating shaft 12 magnet 13 frame 20 stator 21 stator core 21a teeth 22 winding 30 molded resin 40 bearings 42, 43 holding portion 50 first housing ring 51 protrusion 52 outer peripheral wall 60 second housing ring 61 protrusion 62 lid portion 70 vibration-isolating member 71 rubber material 71a opening 72 metal ring 80 oil recovery mechanism 81 slinger 82 felt 83 washer 84 holder 100 support base 110 motor receiving portion 120 locking piece 200 fastening member 210 metal band 211 locking hole 220 screw P1 first inner peripheral line P2 second inner peripheral line R1 first inner peripheral surface R2 Second inner peripheral surface S1 First support part (support part) S2 Second support part (support part) a1 First point a2 Second point

Claims

1. An electric motor attached to a support base, comprising: a rotor having a rotating shaft extending in the axial direction; a stator; and a bearing rotatably supporting the rotating shaft, wherein the electric motor has two support portions as locations supported by the support base, and in the axial direction, the two support portions are at different positions from each other, and the positions of each of the two support portions are different from the position of the bearing.

2. The electric motor according to claim 1, further comprising two vibration damping members supported by the support base, wherein one of the two vibration damping members forms one of the two support portions, and the other of the two vibration damping members forms the other of the two support portions.

3. The stator is molded with a mold resin, and the electric motor includes two housing rings fixed to the mold resin. One of the two housing rings has one of the two vibration damping members attached thereto, and the other of the two housing rings has the other of the two vibration damping members fixed thereto. The material constituting the two housing rings is different from the material constituting the mold resin. The electric motor according to claim 2.

4. The rigidity of the two housing rings is higher than the rigidity of the mold resin. The electric motor according to claim 3.

5. At least one of the two housing rings has a cylindrical outer peripheral wall, and at least a part of the outer peripheral wall is fixed to the mold resin. The electric motor according to claim 4.

6. The bearing and the rotating shaft are in contact with each other at two holding portions. In the axial direction, when the distance between the two support portions is D and the distance between the two holding portions is d, the relationship D > d is satisfied. The electric motor according to any one of claims 1 to 5.

7. In the axial direction, the two holding portions are present between the two support portions. The electric motor according to claim 6.

8. The bearing is a sliding bearing that supports two locations of the rotating shaft with one bearing. The electric motor according to any one of claims 1 to 5.

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