WO2011141958A1 - Electric motor and electric device including the electric motor - Google Patents

Electric motor and electric device including the electric motor Download PDF

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Publication number
WO2011141958A1
WO2011141958A1 PCT/JP2010/003204 JP2010003204W WO2011141958A1 WO 2011141958 A1 WO2011141958 A1 WO 2011141958A1 JP 2010003204 W JP2010003204 W JP 2010003204W WO 2011141958 A1 WO2011141958 A1 WO 2011141958A1
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WO
WIPO (PCT)
Prior art keywords
iron core
rotating body
electric motor
dielectric layer
shaft
Prior art date
Application number
PCT/JP2010/003204
Other languages
English (en)
French (fr)
Inventor
Haruhiko Kado
Hirofumi Mizukami
Akihiko Watanabe
Takehiko Hasegawa
Original Assignee
Panasonic Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Panasonic Corporation filed Critical Panasonic Corporation
Priority to PCT/JP2010/003204 priority Critical patent/WO2011141958A1/en
Priority to CN2010900014368U priority patent/CN202696316U/zh
Publication of WO2011141958A1 publication Critical patent/WO2011141958A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/28—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
    • H02K1/30—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures using intermediate parts, e.g. spiders
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/40—Structural association with grounding devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
    • H02K5/161—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields radially supporting the rotary shaft at both ends of the rotor

Definitions

  • the present invention relates to an electric motor and to an electric device including the electric motor.
  • the present invention relates more particularly to an electric motor improved to suppress the occurrence of electrolytic corrosion in the bearing and to an electric device including the electric motor.
  • an electric motor has been driven, using an inverter of a pulse width modulation system (hereinafter, referred to as a PWM system), in many cases.
  • a PWM system pulse width modulation system
  • the neutral point potential of the winding is not zero, which causes a potential difference between the outer ring and the inner ring of the bearing (hereinafter, referred to as a shaft voltage).
  • the shaft voltage includes a high-frequency component caused by switching.
  • the power supply circuit of the driving circuit (including a control circuit) for driving the electric motor, using an inverter of the PWM system, is electrically insulated from the primary circuit of the power supply circuit and the ground earth on the primary circuit side.
  • the conventional measures considered to suppress electrolytic corrosion are as follows: (1) Providing electrical continuity between the bearing inner ring and the bearing outer ring; (2) Providing electrical insulation between the bearing inner ring and the bearing outer ring; and (3) Reducing the shaft voltage. Examples of the specific methods for (1) include using a conductive lubricant in the bearing.
  • the conductive lubricant has conductivity deteriorated with a lapse of time, and lacks sliding reliability.
  • a method for disposing brushes on the rotary shaft to provide electrical continuity is considered.
  • this method produces brush abrasion powder and requires a space.
  • Examples of the specific methods for (2) include changing the iron balls in the bearing to non-conductive ceramic balls. This method is highly effective in suppressing electrolytic corrosion, but takes high cost. Thus, this method cannot be used for general-purpose electric motors.
  • the following method is conventionally known. A stator iron core and a conductive bracket are short-circuited to change the capacitance and to reduce the shaft voltage (see Patent Literature 1, for example).
  • Z is an impedance
  • j is an imaginary number
  • w is an angular frequency
  • C is a capacitance
  • R is a resistance.
  • an electric motor that is used in a washing machine or a dish washer/dryer, for example, installed in a wet place, and thus can cause electric shock requires independent insulation (hereinafter, referred to as additional insulation), besides the insulation in the charge part (basic insulation).
  • additional insulation independent insulation
  • an electric motor that is used in those except the above electric appliances e.g. an air-conditioner indoor unit, air-conditioner outdoor unit, hot water supplier, and air cleaner, does not cause electric shock and thus requires no additional insulation. For this reason, in an electric motor used in an air-conditioner indoor unit, air-conditioner outdoor unit, hot water supplier, and air cleaner, its rotor does not have an insulated structure.
  • the impedance of the rotor side (bearing inner-ring side) is in a low state.
  • the stator side (bearing outer-ring side) has an insulated structure, and thus the impedance is in a high state.
  • the potential on the bearing inner-ring side is high
  • the potential on the bearing outer-ring side is low.
  • This unbalanced state can generate a high shaft voltage.
  • Such a high shaft voltage can cause electrolytic corrosion in the bearing.
  • the stator iron core and the bracket are short-circuited so that the capacitance component between them is eliminated.
  • the following case can be considered: when the impedance is unbalanced by the use environment of the electric motor, or variations in the assembling accuracy of the stator and the rotor, the shaft voltage increases on the contrary, which facilitates the occurrence of electrolytic corrosion.
  • the power supply circuit of the driving circuit including a control circuit for driving the electric motor, using an inverter of the PWM system, is electrically insulated from the primary circuit of the power supply circuit and the ground earth on the primary circuit side.
  • the present invention is directed to provide an electric motor capable of suppressing the occurrence of electrolytic corrosion in the bearing, and an electric device including the electric motor.
  • the electric motor of the present invention has the following elements: a stator having a stator iron core, the stator iron core having a winding wound thereon; a rotor having the following elements: a rotating body holding a permanent magnet in the circumferential direction so that the permanent magnet faces the stator; and a shaft having the rotating body fastened thereto so as to penetrate through the center of the rotating body; a bearing for journaling the shaft rotatably; and a bracket for fixing the bearing.
  • the rotating body has the following elements: an outer iron core forming an outer peripheral part of the rotating body; an inner iron core forming an inner peripheral part fastened to the shaft; and a dielectric layer disposed between the outer iron core and the inner iron core.
  • Each of the outer iron core and the inner iron core is formed by laminating steel sheets.
  • the high-frequency potentials on the bearing inner-ring side and the bearing outer-ring side can be equalized and balanced. Since the potential difference between the inner ring and the outer ring of the bearing can be reduced, the occurrence of electrolytic corrosion in the bearing caused by high-frequency waves resulting from PWM, for example, can be suppressed. Further, the capacitance can be varied by changing the width or material of the dielectric layer. Thus, the impedance of the rotor side can be set optimally.
  • the dielectric layer indicates a layer for intentionally changing the dielectric constant and thickness of a dielectric, or the surface area of a conductor (electrode) in contact with the dielectric.
  • the dielectric layer is intended to serve as if it is a dielectric element interposed between the shaft and the rotating body.
  • the electric device of the present invention includes the above electric motor. As described above, in the electric motor of the present invention, the impedance of the rotor side (bearing inner-ring side) is increased so as to approximate to the impedance of the stator side (bearing outer-ring side). Thus, the high-frequency potentials on the bearing inner-ring side and the bearing outer-ring side can be balanced. Therefore, the present invention can provide an electric motor capable of suppressing the occurrence of electrolytic corrosion in the bearing and having high productivity and reliability, and an electric device including the electric motor.
  • Fig. 1 is a structural diagram showing a section of a brushless motor in accordance with a first exemplary embodiment of the present invention.
  • Fig. 2 is a diagram schematically showing an essential part of the motor.
  • Fig. 3 is a diagram schematically showing a partial section of a rotating body of the motor.
  • Fig. 4 is an external perspective view showing a specific structural example of the rotating body of the motor.
  • Fig. 5 is a development perspective view showing the specific structural example of the rotating body of the motor.
  • Fig. 6 is an external perspective view showing a specific structural example of a rotating body of a brushless motor in accordance with a second exemplary embodiment of the present invention.
  • Fig. 7 is a development perspective view showing the specific structural example of the rotating body of the motor.
  • Fig. 1 is a structural diagram showing a section of a brushless motor in accordance with a first exemplary embodiment of the present invention.
  • Fig. 2 is a diagram schematically showing an essential part of the motor.
  • FIG. 8 is an external perspective view showing a specific structural example of a rotating body of a brushless motor in accordance with a third exemplary embodiment of the present invention.
  • Fig. 9 is a development perspective view showing the specific structural example of the rotating body of the motor.
  • Fig. 10 is an external perspective view showing a specific structural example of a rotating body of a brushless motor in accordance with a fourth exemplary embodiment of the present invention.
  • Fig. 11 is a development perspective view showing the specific structural example of the rotating body of the motor.
  • Fig. 12 is a schematic diagram showing a structure of an air-conditioner indoor unit as an example of an electric device in accordance with a fifth exemplary embodiment of the present invention.
  • Fig. 1 is a structural diagram showing a section of a brushless motor in accordance with the first exemplary embodiment of the present invention.
  • a description is provided for a brushless motor, i.e. an electric motor, included in an air conditioner as an electric device, for driving a blower fan.
  • a description is provided for an inner-rotor type electric motor, in which a rotor is disposed rotatably on the inner peripheral side of a stator.
  • stator winding 12 is wound on stator iron core 11, via resin 21, i.e. an insulator for insulating stator iron core 11.
  • stator iron core 11 is molded with insulating resin 13, as a mold material, together with other members to be fixed. In this exemplary embodiment, these members are integrally molded in this manner, to form stator 10 having a substantially cylindrical contour.
  • rotor 14 On the inner side of stator 10, rotor 14 is disposed with a clearance provided between them.
  • Rotor 14 has a disc-shaped rotating body 30 including rotor iron core 31, and has shaft 16 having rotating body 30 fastened thereto so as to penetrate through the center of rotating body 30.
  • Rotating body 30 holds magnet 32, i.e. a permanent magnet, such as a ferrite resin magnet, in the circumferential direction so that the magnet faces the inner peripheral side of stator 10.
  • Rotor iron core 31 is formed by laminating steel sheets.
  • rotating body 30 is structured to have outer iron core 31a, dielectric layer 50, and inner iron core 31b in this order from magnet 32 in the outermost peripheral part toward shaft 16 on the inner peripheral side.
  • Outer iron core 31a forms the outer peripheral part of rotor iron core 31;
  • inner iron core 31b forms the inner peripheral part of rotor iron core 31.
  • Fig. 1 shows a structural example of rotating body 30 integrally formed of these rotor iron core 31, dielectric layer 50, and magnet 32. In this manner, the inner peripheral side of stator 10 faces the outer peripheral side of rotating body 30.
  • Two bearings 15 for journaling shaft 16 are attached to shaft 16 of rotor 14.
  • Each of bearings 15 is a bearing including a plurality of iron balls.
  • connection line 20 including lead wires for applying the power supply voltage of the winding, the power supply voltage of the control circuit, and the control voltage for controlling the number of rotations, and the ground wire of the control circuit, is connected to printed circuit board 18.
  • the power supply circuit for supplying the power supply voltage of the winding, the power supply circuit for supplying the power supply voltage of the control circuit, the lead wire for applying the control voltage, and the ground wire of the control circuit are connected to printed circuit board 18 on which the driving circuit is mounted, and are electrically insulated from the ground earth. That is, these power supply circuits, for example, are electrically insulated from any of the primary (power supply) circuit with respect to the power supply circuit for supplying the power supply voltage of the winding, the primary (power supply) circuit with respect to the power supply circuit for supplying the power supply voltage of the control circuit, the ground earth connected to these primary (power supply) circuits, and independently grounded earth.
  • Fig. 2 is a diagram schematically showing an essential part of the brushless motor of Fig. 1. As shown in Fig. 2, in rotating body 30, magnet 32 is formed in the outermost peripheral part.
  • dielectric layer 50 is a layer formed of an insulating resin. In this exemplary embodiment, such dielectric layer 50 is formed to suppress electrolytic corrosion.
  • rotating body 30 is integrally formed of magnet 32, outer iron core 31a, an insulating resin forming dielectric layer 50, and inner iron core 31b.
  • rotating body 30 is fastened to shaft 16.
  • dielectric layer 50 is a layer formed of an insulating resin, i.e.
  • dielectric layer 50 is formed of an insulating resin having a predetermined dielectric constant, and high-frequency current can flow between outer iron core 31a and inner iron core 31b. If such dielectric layer 50 is not formed, the impedance between the bracket and the stator iron core is high and, in contrast, the impedance between the shaft electrically connected to the rotating body and the stator iron core is low, as described above. For example, PWM high-frequency current generated from the stator iron core, flows into the equivalent circuit having such impedance components. The high-frequency current can cause a potential difference between the outer ring electrically connected to the bracket and the shaft on the bearing inner-ring side.
  • dielectric layer 50 shown in Fig. 2 is formed in the rotating body that has low impedance and is formed of the iron core only.
  • the impedance of rotor 14 is increased so as to approximate to the impedance of the side of bracket 17. That is, forming dielectric layer 50 between outer iron core 31a and inner iron core 31b makes rotor 14 have a structure where the capacitance caused by dielectric layer 50 is equivalently series-connected.
  • the impedance of rotor 14 can be increased.
  • the increased impedance of rotor 14 increases the voltage drop in the high-frequency waves flowing from rotor 14 to shaft 16, thereby reducing the potential generated in shaft 16 by the high-frequency current.
  • the potential difference caused by the high-frequency current between the outer ring of bearing 15 electrically connected to bracket 17 and shaft 16 on the inner-ring side of bearing 15 is reduced.
  • the bearing inner ring and the bearing outer ring are balanced always at a low potential with a small potential difference.
  • This state suppresses the occurrence of electrolytic corrosion in the bearing.
  • the capacitance can be varied by changing the width or material of dielectric layer 50.
  • the impedance of the side of rotor 14 can be set optimally.
  • the capacitance caused by dielectric layer 50 can be reduced by the following method: reducing the dielectric constant of the insulating resin forming dielectric layer 50, increasing the thickness of the insulating resin (interelectrode distance), or reducing the electrode area, for example.
  • the impedance of rotor 14 can be increased.
  • dielectric layer 50 separates rotating body 30 into outer iron core 31a and inner iron core 31b.
  • rotating body 30 can be formed without a shaft attached, and thus the productivity can be enhanced in comparison to the structure where the dielectric layer is formed between the shaft and the rotor iron core. Further, in the structure of Fig. 2, even shaft 16 of a different type can be fastened by caulking or press-fitting. Thus, this structure can facilitate the changeover of the types, and improve the productivity. Further, each of outer iron core 31a and inner iron core 31b is formed by laminating steel sheets. In this exemplary embodiment, such a structure enhances the joining strength in the joining surface between outer iron core 31a and dielectric layer 50 and the joining surface between inter iron core 31a and dielectric layer 50.
  • Fig. 3 is a diagram schematically showing a partial section of rotating body 30. Fig.
  • FIG. 3 is a schematic diagram for facilitating understanding of the state of rotating body 30.
  • the dimensions in Fig. 3 are different from actual dimensions.
  • outer iron core 31a is formed by laminating a plurality of steel sheets 311a
  • inner iron core 31b is formed by laminating a plurality of steel sheets 311b.
  • Dielectric layer 50 is disposed between outer iron core 31a and inner iron core 31b.
  • laminating steel sheets 311a and 311b forms microscopic projections and depressions by each of steel sheets 311a and 311b in joining surfaces 41 on the ion core sides.
  • dielectric layer 50 is formed of a resin, and thus has a certain degree of elasticity in comparison to steel sheets 311a and 311b.
  • dielectric layer 50 wedges into the depressions formed between the steel sheets in joining surfaces 41 between the iron cores and dielectric layer 50, as shown in Fig. 3.
  • This improves the adherence between outer iron core 31a and inner iron core 31b and dielectric layer 50, and enhances the joining strength.
  • the detachment strength and the strength against axially-applied force can be enhanced.
  • this structure can provide a sufficient strength, prevent the occurrence of electrolytic corrosion, and ensure sufficient reliability, even in a structure where dielectric layer 50 is formed in rotating body 30.
  • FIG. 4 and Fig. 5 are diagrams showing a specific structural example of rotating body 30 of the brushless motor in accordance with this exemplary embodiment.
  • Fig. 4 is an external perspective view of rotating body 30;
  • Fig. 5 is a development perspective view of rotating body 30 of Fig. 4.
  • each of outer iron core 31a and inner iron core 31b has a plurality of projections in the radial direction.
  • outer iron core 31a has a substantially annular shape. More specifically, the outer iron core has a circular shape on its outer peripheral side, and radial projections spaced at regular intervals on its inner peripheral side.
  • Inner iron core 31b also has a substantially annular shape. More specifically, the inner iron core has a circular shape on its inner peripheral side, and radial projections spaced at regular intervals on its outer peripheral side. The projections of outer iron core 31a and the projections of inner iron core 31b are disposed in positions facing each other. Further, between outer iron core 31a and inner iron core 31b in the radial direction, dielectric layer 50 integrally formed with rotor iron core 31 is present in a shape such that a convex projection shape and a concave projection shape are repeated in a circle. If dielectric layer 50 is shaped into a complete ring, a slip can occur during rotation. In contrast, when dielectric layer 50 is formed into the shape of Fig. 4 and Fig.
  • Rotating body 30 of Fig. 4 and Fig. 5 is a structural example where dielectric layer 50 includes air hole parts 40, i.e. substantially circular air holes, in part of the dielectric layer.
  • air hole parts 40 are formed in the thick portion of dielectric layer 50.
  • the sink mark is a phenomenon such that the resin cooled and taken out is shrunken in comparison to its molten state during formation.
  • the dielectric constant of air is approximately 1, and thus is extremely smaller than that of insulating resin. That is, forming an air layer or air hole in part of the insulating resin can reduce the capacitance.
  • outer contact area Sa is an area of the contact part between dielectric layer 50 and outer iron core 31a in the portions where the distance between outer iron core 31a and inner iron core 31b in the radial direction is at the minimum.
  • Inner contact area Sb is an area of the contact part between dielectric layer 50 and inner iron core 31b in the portions where the distance between outer iron core 31a and inner iron core 31b in the radial direction is at the minimum.
  • Shaft contact area Si is an area of the contact portion between shaft 16 and inner iron core 31b.
  • rotating body 30 is formed so that at least one of outer contact area Sa and inner contact area Sb is substantially equal to shaft contact area Si. That is, at least one of outer contact area Sa and inner contact area Sb is slightly larger, equal to, or smaller than shaft contact area Si.
  • FIG. 6 and Fig. 7 are diagrams showing a specific structural example of rotating body 30 of a brushless motor in accordance with the second exemplary embodiment of the present invention.
  • Fig. 6 is an external perspective view of rotating body 30;
  • Fig. 7 is a development perspective view of rotating body 30 of Fig. 6.
  • each of outer iron core 31a and inner iron core 31b has a plurality of projections in the radial direction.
  • outer iron core 31a has a substantially annular shape. More specifically, the outer iron core has a circular shape on its outer peripheral side, and radial projections spaced at regular intervals on its inner peripheral side.
  • Inner iron core 31b also has a substantially annular shape.
  • the inner iron core has a circular shape on its inner peripheral side, and radial projections spaced at regular intervals on its outer peripheral side.
  • the projections of outer iron core 31a and the depressions of inner iron core 31b are disposed in positions facing each other.
  • dielectric layer 50 integrally formed with rotor iron core 31 is present in a shape such that a convex projection shape and a concave projection shape are repeated in a circle.
  • slip-preventing projections are interposed between dielectric layer 50 and the iron core. This structure can prevent a slip and enhance the rotational strength.
  • FIG. 8 and Fig. 9 are diagrams showing a specific structural example of rotating body 30 of a brushless motor in accordance with the third exemplary embodiment of the present invention.
  • Fig. 8 is an external perspective view of rotating body 30;
  • Fig. 9 is a development perspective view of rotating body 30 of Fig. 8.
  • each of outer iron core 31a and inner iron core 31b has a plurality of projections in the radial direction.
  • outer iron core 31a has a substantially annular shape. More specifically, the outer iron core has a circular shape on its outer peripheral side, and radial projections spaced at regular intervals on its inner peripheral side.
  • Inner iron core 31b has a substantially annular shape.
  • the inner iron core has a circular shape on its inner peripheral side, and radial projections spaced at regular intervals on its outer peripheral side. Further, each of the outer iron core and the inner iron core is divided into a plurality of parts (three parts, in this exemplary embodiment) also in the axial direction.
  • the projections of outer iron cores 31a1 face the depressions of outer iron core 31a2 axially adjacent to outer iron cores 31a1 so that projections are disposed alternately.
  • inner iron core 31b is divided into a plurality of parts in the axial direction.
  • the projections of inner iron cores 31b1 face the depressions of inner iron core 31a2 axially adjacent to inner iron cores 31a1 so that projections are disposed alternately.
  • Each of iron core parts divided in the axial direction may be formed of one steel sheet or a lamination of a plurality of steel sheets.
  • dielectric layer 50 is integrally formed with rotor iron core 31 between outer iron core 31a and inner iron core 31b in the radial direction, and is present in a shape such that a convex projection shape and a concave projection shape are repeated in a circle in the radial direction and are alternately stacked in the axial direction.
  • This structure prevents a slip in the rotation direction and enhances the rotational strength as described in the first and the second exemplary embodiments.
  • the projections for preventing detachment are formed also in the axial direction, an electric motor highly reliable in use under axial load conditions can be provided.
  • FIG. 10 and Fig. 11 are diagrams showing a specific structural example of rotating body 30 of a brushless motor in accordance with the fourth exemplary embodiment of the present invention.
  • Fig. 10 is an external perspective view of rotating body 30;
  • Fig. 11 is a development perspective view of rotating body 30 of Fig. 10.
  • each of outer iron core 31a and inner iron core 31b of rotating body 30 is also divided into a plurality of parts (three parts, in this exemplary embodiment) in the axial direction.
  • Outer iron core 31a is formed of outer iron core 31a1 that has a plurality of projections in the radial direction in a manner similar to that of the third exemplary embodiment, for example, and outer iron cores 31a3 each having a substantially circular shape.
  • outer iron core 31a outer iron core 31a1 and outer iron core 31a3 are disposed alternately in the axial direction.
  • Inner iron core 31b is formed of inner iron core 31b1 that has a plurality of projections in the radial direction in a manner similar to that of the third exemplary embodiment, for example, and inner iron cores 31b3 each having a substantially circular shape.
  • inner iron core 31b1 and inner iron core 31b3 are disposed alternately in the axial direction.
  • the iron core of the rotor is formed by punching an electromagnetic steel sheet with a pressing machine, and laminating and caulking the punched sheets in the pressing machine.
  • Combining simple shapes as shown in this exemplary embodiment provides advantages of simplifying the structures of the press dies, and improving productivity.
  • Even the above structure includes projections for preventing a slip in the rotation direction and enhancing the rotational strength, and projections for preventing detachment in the axial direction, similar to that of the third exemplary embodiment.
  • a highly reliable electric motor capable of preventing a slip in the rotation direction and detachment in the axial direction, and enhancing the rotational strength can be provided.
  • FIG. 12 is a schematic diagram showing a structure of an air-conditioner indoor unit, as an example of an electric device in accordance with the fifth exemplary embodiment of the present invention.
  • brushless motor 201 is included in case 211 of air-conditioner indoor unit 200.
  • Cross flow fan 212 is attached to the rotary shaft of brushless motor 201.
  • Brushless motor 201 is driven by motor drive unit 213. By energization of motor drive unit 213, brushless motor 201 is rotated, and thereby cross flow fan 212 is rotated.
  • the brushless motor 201 By the rotation of cross flow fan 212, air conditioned by the heat exchanger for the indoor unit (not shown) is blown into the room.
  • brushless motor 201 the brushless motor of each of the above exemplary embodiments, for example, can be used.
  • the electric device of the present invention has a brushless motor, and a case including the brushless motor.
  • the brushless motor the electric device uses the brushless motor of the present invention structured as above.
  • a brushless motor included in an air-conditioner indoor unit is used for the electric device of the exemplary embodiment of the present invention.
  • the present invention can be applied to a brushless motor included in an air-conditioner outdoor unit, and brushless motors included in other electric devices, e.g.
  • the electric motor of the present invention includes the following elements: a stator having a stator iron core, the stator iron core having a winding wound thereon; a rotor having the following elements: a rotating body holding a permanent magnet in the circumferential direction so that the permanent magnet faces the stator; and a shaft having the rotating body fastened thereto so as to penetrate through the center of the rotating body; a bearing for journaling the shaft rotatably; and a bracket for fixing the bearing.
  • the rotating body has the following elements: an outer iron core forming an outer peripheral part of the rotating body; an inner iron core forming an inner peripheral part fastened to the shaft; and a dielectric layer formed between the outer iron core and the inner iron core.
  • Each of the outer iron core and the inner iron core is formed by laminating steel sheets.
  • the rotating body has a structure easy to manufacture, and thus the productivity of the rotating body can be improved.
  • Each of the outer iron core and inner iron core is formed by laminating steel sheets. This structure can enhance the joining strength in the joining surface between the outer iron core and the dielectric layer, and the joining surface between the inter iron core and the dielectric layer, and ensure sufficient reliability.
  • each of the outer iron core and the inner iron core has a plurality of projections in the radial direction, which forms projecting portions between the dielectric layer and the iron core.
  • This structure can prevent a slip of the dielectric layer during rotation.
  • the iron core is divided into a plurality of parts in the axial direction. Thereby, projecting portions are formed between the dielectric layer and the iron core also in the axial direction.
  • This structure can enhance the strength against axially-applied force.
  • air holes are formed as air hole parts in part of the dielectric layer. This structure can reduce the sink marks of a resin during formation when the resin is integrally formed with the outer iron core and the inner iron core, and improve the productivity of the rotor.
  • the present invention can provide an electric motor capable of suppressing the occurrence of electrolytic corrosion in the bearing. Further, by incorporating the electric motor of the present invention into an electric device, the present invention can provide an electric device including the electric motor capable of suppressing the occurrence of electrolytic corrosion in the bearing. Further, the description has been provided, using an inner-rotor type electric motor, in which a rotor is disposed rotatably on the inner peripheral side of a stator, as an example.
  • the dielectric layer as described above in an outer-rotor type electric motor, in which a rotor is disposed rotatably on the outer peripheral side of a stator, and in a twin-rotor type electric motor, in which rotors are disposed on both inner peripheral side and outer peripheral side.
  • the contact area between the dielectric layer and the outer iron core or the dielectric layer and the inner iron core in the portions where the distance between the outer iron core and the inner iron core in the radial direction is at the minimum is slightly larger, equal to, or smaller than the contact area between the shaft and the inner iron core. This structure can increase the impedance of the rotor.
  • the power supply circuit of the driving circuit (including the control circuit) for driving the electric motor, using an inverter of the PWM system, is electrically insulated from the primary circuit of the power supply circuit and the ground earth on the primary circuit side. Even without using a conventional structure where the stator iron core of an electric motor is electrically connected to the ground earth, the advantage of suppressing electrolytic corrosion in the bearing can be obtained.
  • the electric motor of the present invention is capable of reducing the shaft voltage, and is most suitable for suppressing the occurrence of electrolytic corrosion in the bearing. For this reason, the present invention is useful in electric motors included mainly in electric devices where the low cost and long life of the electric motors are requested, e.g. an air-conditioner indoor unit, air-conditioner outdoor unit, hot water supplier, and air clearer.

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PCT/JP2010/003204 2010-05-12 2010-05-12 Electric motor and electric device including the electric motor WO2011141958A1 (en)

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PCT/JP2010/003204 WO2011141958A1 (en) 2010-05-12 2010-05-12 Electric motor and electric device including the electric motor
CN2010900014368U CN202696316U (zh) 2010-05-12 2010-05-12 电动机和包括电动机的电气设备

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PCT/JP2010/003204 WO2011141958A1 (en) 2010-05-12 2010-05-12 Electric motor and electric device including the electric motor

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103545949A (zh) * 2012-07-11 2014-01-29 松下电器产业株式会社 电动机以及具有该电动机的电气设备
WO2018056359A1 (ja) * 2016-09-21 2018-03-29 株式会社富士通ゼネラル 永久磁石電動機
US10326323B2 (en) 2015-12-11 2019-06-18 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US10693336B2 (en) 2017-06-02 2020-06-23 Whirlpool Corporation Winding configuration electric motor
DE102019113039A1 (de) * 2018-12-21 2020-06-25 Carl Freudenberg Kg Anordnung
US10704180B2 (en) 2016-09-22 2020-07-07 Whirlpool Corporation Reinforcing cap for a tub rear wall of an appliance
CN112821678A (zh) * 2021-03-22 2021-05-18 广东威灵电机制造有限公司 无刷电机及电气设备
US12031260B2 (en) 2022-09-09 2024-07-09 Whirlpool Corporation Reinforcing cap for a tub rear wall of an appliance

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CN103545949A (zh) * 2012-07-11 2014-01-29 松下电器产业株式会社 电动机以及具有该电动机的电气设备
US10897167B2 (en) 2015-12-11 2021-01-19 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US11909265B2 (en) 2015-12-11 2024-02-20 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US11641138B2 (en) 2015-12-11 2023-05-02 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US10326323B2 (en) 2015-12-11 2019-06-18 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US11374448B2 (en) 2015-12-11 2022-06-28 Whirlpool Corporation Multi-component rotor for an electric motor of an appliance
US20190214875A1 (en) * 2016-09-21 2019-07-11 Fujitsu General Limited Permanent magnet electric motor
US10797553B2 (en) 2016-09-21 2020-10-06 Fujitsu General Limited Permanent magnet electric motor
EP3518389A4 (en) * 2016-09-21 2020-05-06 Fujitsu General Limited PERMANENT MAGNETIC MOTOR
JP2018050397A (ja) * 2016-09-21 2018-03-29 株式会社富士通ゼネラル 永久磁石電動機
WO2018056359A1 (ja) * 2016-09-21 2018-03-29 株式会社富士通ゼネラル 永久磁石電動機
US10704180B2 (en) 2016-09-22 2020-07-07 Whirlpool Corporation Reinforcing cap for a tub rear wall of an appliance
US11473231B2 (en) 2016-09-22 2022-10-18 Whirlpool Corporation Reinforcing cap for a tub rear wall of an appliance
US10693336B2 (en) 2017-06-02 2020-06-23 Whirlpool Corporation Winding configuration electric motor
US11482901B2 (en) 2017-06-02 2022-10-25 Whirlpool Corporation Winding configuration electric motor
DE102019113039A1 (de) * 2018-12-21 2020-06-25 Carl Freudenberg Kg Anordnung
CN112821678A (zh) * 2021-03-22 2021-05-18 广东威灵电机制造有限公司 无刷电机及电气设备
US12031260B2 (en) 2022-09-09 2024-07-09 Whirlpool Corporation Reinforcing cap for a tub rear wall of an appliance

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