JP2015019514A - Motor and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor in which liquid is prevented from remaining in a recess formed on an insulation member of a rotor, and an air conditioner having the motor.SOLUTION: The motor includes a shaft 7, a rotor 11 fixed to the shaft 7 and including a permanent magnet 31, and a stator 12 housing the rotor 11 and generating a revolving magnetic field. The rotor 11 includes an inner peripheral side rotor 33 fastened to the shaft 7, an outer peripheral side rotor 32 constituting the outer peripheral part of the rotor 11 and holding the permanent magnet 31, and an insulation member 34 made of an insulating body and provided between the inner peripheral side rotor 33 and the outer peripheral side rotor 32. A recess 35 concave in the axial direction of the shaft 7 is formed on the insulation member 34. A wall surface 35a of the recess 35 on the side of the outer peripheral side rotor 32 is inclined with respect to the axis of the shaft 7.

Description

  The present invention relates to a motor and an air conditioner using the motor.

  When a motor is operated using an inverter, noise is generated from the motor along with a switching operation of a transistor mounted on the circuit. In order to reduce the noise generated from the motor, it has been conventionally performed to set the inverter carrier frequency high. A shaft voltage is generated on the motor shaft based on electromagnetic induction. However, as the carrier frequency of the inverter increases, this shaft voltage increases, and the potential difference between the inner ring and the outer ring of the bearing that supports the shaft increases. Become. For this reason, a great amount of current flows through the bearing, and corrosion called electric corrosion occurs on the raceway surfaces in the circumferential direction of the inner ring and the outer ring of the bearing, and the rolling surfaces of the rolling elements arranged between the inner ring and the outer ring. When electric corrosion occurs in the bearing, abnormal noise is generated from the bearing or the durability of the bearing is deteriorated. In order to suppress such electrolytic corrosion of the bearing, the following techniques have been proposed.

  Patent Document 1 discloses a brushless motor in which a stator iron core and a bracket that supports a bearing are short-circuited via an iron core connection terminal (cable) and a bracket connection terminal (cable). In this prior art, the stator core and the bracket are short-circuited to reduce the voltage applied to the bearing and to suppress the electrolytic corrosion of the bearing. However, in this conventional technique, the impedance of the rotor (rotor) and the impedance of the stator (stator) may be in an unbalanced state and a high shaft voltage may be generated. Could occur.

  Patent Document 2 discloses an electric motor in which a dielectric layer formed of an insulating resin is provided between a shaft and an outer periphery of a rotor in order to solve the problems of the technique disclosed in Patent Document 1. In this prior art, the impedance of the rotor is increased by the dielectric layer, so that the impedance of the rotor is approximated to the impedance of the stator, which is a high impedance. As a result, the potential difference between the inner ring and the outer ring of the bearing is reduced, and the electric corrosion of the bearing is to be suppressed.

JP 2007-159302 A (Claim 1, FIG. 1) International Publication No. 2009/113311 (Claim 1, FIG. 3)

  In the insulating member provided between the inner peripheral side and the outer peripheral side of the rotor, it is desirable to form a concave portion recessed in the axial direction of the shaft for the following reasons. For example, when an insulating member is formed by injection molding, shrinkage (sink) after molding tends to occur as the thickness of the member increases. In order to avoid peeling between the insulating member and the rotor due to such contraction, a recess is formed as so-called meat stealing. Moreover, the cooling efficiency at the time of injection molding can be improved by forming a recessed part. Further, by forming the recess in the insulating member, the amount of material used to form the insulating member can be reduced, and the product cost can be reduced.

  However, in the recess formed in the insulating member, when the inside of the motor becomes highly humid, liquids such as condensed water that moisture in the air has condensed may accumulate, which is a factor that promotes deterioration of the insulating member, that is, motor insulation deterioration It becomes. Further, when liquid accumulates in the recess formed in the insulating member, an unbalance occurs in the load of the rotor, and eccentricity occurs in the rotation of the rotor, generating noise.

  The present invention has been made against the background of the above problems, and provides a motor that suppresses liquid remaining in a recess formed in an insulating member of a rotor and an air conditioner having the motor.

  A motor according to the present invention comprises a shaft, a rotor fixed to the shaft and having a magnet, and a stator that houses the rotor and generates a rotating magnetic field, and the rotor is fastened to the shaft. A peripheral rotor, an outer peripheral rotor that constitutes an outer peripheral portion of the rotor, and holds the magnet; an insulating member that is formed of an insulator and provided between the inner peripheral rotor and the outer peripheral rotor; The insulating member is formed with a recess recessed in the axial direction of the shaft, and a wall surface of the recess on the outer rotor side is inclined with respect to the shaft axis. .

  In the present invention, the outer peripheral rotor-side wall surface of the recess of the insulator is inclined with respect to the shaft axis. For this reason, the residual of the liquid to the recessed part formed in the insulating member of the rotor can be suppressed.

1 is a schematic diagram showing an air conditioner 1 according to Embodiment 1. FIG. 1 is a perspective view showing a motor 2 according to Embodiment 1. FIG. 1 is a cross-sectional view showing a motor 2 according to Embodiment 1. FIG. FIG. 2 is a perspective view showing a rotor 11 in the first embodiment. FIG. 2 is a cross-sectional view showing a rotor 11 in the first embodiment. FIG. 10 is a cross-sectional view showing the operation of the rotor 51 in Comparative Example 1. FIG. 6 is a cross-sectional view showing the operation of the rotor 11 in the first embodiment. FIG. 6 is a cross-sectional view showing a rotor 11 in a second embodiment.

  Embodiments of a motor and an air conditioner according to the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an air conditioner 1 according to Embodiment 1. FIG. The air conditioner 1 will be described with reference to FIG. As shown in FIG. 1, the air conditioning apparatus 1 includes an outdoor unit 1a and an indoor unit 1b. Among these, the outdoor unit 1a is provided with a blower 21, a compressor 22, a first heat exchanger 23 and an expansion means 24, and the indoor unit 1b is provided with a second heat exchanger 25. Yes. The blower 21 discharges the air heat-exchanged by the first heat exchanger 23 to the outside of the outdoor unit 1a. And these compressor 22, the 1st heat exchanger 23, the expansion means 24, and the 2nd heat exchanger 25 are connected by piping, and the refrigerant | coolant is circulating through this piping. Thereby, the refrigerant circuit is constituted.

  Next, the motor 2 used for the blower 21 will be described. FIG. 2 is a perspective view showing the motor 2 according to the first embodiment. As shown in FIG. 2, the motor 2 includes a motor main body 2a that generates a rotating magnetic field and rotates the shaft 7, and a base 3 on which the motor main body 2a is placed. The base 3 has, for example, a quadrangular shape, and the peripheral portion is bent to form a bent portion 3a. And the one end part of the terminal cable 4 is attached to the base 3, and the other end part of this terminal cable 4 is connected to the power supply (not shown) installed in the inside of the outdoor unit 1a. . Then, electric power is supplied from the power source to the motor 2 through the terminal cable 4.

  Next, the motor body 2a, the first bearing 5a, the second bearing 5b, and the bracket 6 will be described. FIG. 3 is a sectional view showing the motor 2 according to the first embodiment. A non-conductive bracket 6 is attached to the lower surface of the motor body 2 a, and the bracket 6 is fastened to the upper surface of the base 3 with screws 16. A rod-shaped shaft 7 is provided at the center of the bracket 6. A first bearing 5a is attached to the base end of the shaft 7, and the shaft 7 is supported by the first bearing 5a. . The bracket 6 covers the outer periphery of the first bearing 5a and holds the first bearing 5a. Further, a drain hole 17 is provided in the center of the bracket 6 in a direction parallel to the shaft 7. When the water or the like enters the inside of the motor 2, the drain hole 17 Is discharged to the outside of the motor 2.

  A cylindrical rotor 11 is fixed coaxially with the shaft 7 around the shaft 7 above the bracket 6 (in the direction of arrow Z1). Further, a cylindrical stator 12 is provided around the rotor 11 coaxially with the shaft 7. The stator 12 includes a stator coil 13 and an insulator 14 around which the stator coil 13 is wound. The stator 12 generates a rotating magnetic field by the current flowing through the stator coil 13, and rotates the rotor 11 at the same cycle as this rotating magnetic field. As the rotor 11 rotates, the shaft 7 installed at the center of the rotor 11 also rotates.

  A second bearing 5b is provided above the rotor 11 (in the direction of arrow Z1). The shaft 7 is smoothly rotated by the second bearing 5b and the first bearing 5a. The housing 15 protects the rotor 11, the stator 12, the first bearing 5a, and the second bearing 5b, and constitutes the outer shell of the motor 2. The housing 15 may be a mold for sealing these members.

  The housing 15 protrudes along the shaft 7 and has a bearing housing 15a that houses the second bearing 5b. A bottomed cylindrical flinger 8 is fixed to the shaft 7 above the bearing housing 15a (in the direction of arrow Z1) so as to cover the bearing housing 15a. The flinger 8 is to prevent foreign substances such as water from entering the motor 2, that is, the housing 15.

  Next, the rotor 11 will be described in detail. FIG. 4 is a perspective view showing the rotor 11 in the first embodiment, and FIG. 5 is a cross-sectional view showing the rotor 11 in the first embodiment. As shown in FIGS. 4 and 5, the rotor 11 includes an inner circumferential rotor 33 fastened to the shaft 7, an outer circumferential rotor 32 that constitutes the outer circumferential portion of the rotor 11, an inner circumferential rotor 33, and an outer circumferential rotor. And an insulating member 34 provided between the two members.

  The outer rotor 32 is formed in a cylindrical shape and is arranged coaxially with the shaft 7. A plurality of permanent magnets 31 are provided on the outer periphery of the outer rotor 32 so as to face the stator 12. The outer rotor 32 is made of a magnetic material and functions as a yoke that increases the magnetic flux of the permanent magnet 31. The inner circumferential rotor 33 is formed in a cylindrical shape and is fastened coaxially with the shaft 7. The inner rotor 33 may be made of either a magnetic material or a nonmagnetic material. The insulating member 34 is formed of an insulator. For example, it is made of a thermoplastic resin such as PBT (polybutylene terephthalate). The insulating member 34 insulates the outer rotor 32 and the inner rotor 33 from each other, thereby increasing the impedance of the rotor 11 and reducing the axial potential.

  The insulating member 34 is formed with a recess 35 that is recessed in the axial direction of the shaft 7. A plurality of recesses 35 are provided on each of the upper surface side and the lower surface side of the rotor 11. In the first embodiment, a case where a plurality of recesses 35 are provided will be described, but the present invention is not limited to this. For example, it may be provided only on the upper surface with respect to the direction of gravity. Moreover, the recessed part 35 does not need to be provided continuously in the circumferential direction.

  A wall surface 35 a on the outer peripheral side rotor 32 side of the recess 35 is inclined with respect to the shaft 7 a of the shaft 7. The insulating member 34 is formed by, for example, injection molding. For example, in a state where the inner circumferential side rotor 33 and the outer circumferential side rotor 32 are disposed coaxially, a mold corresponding to the shape of the insulating member 34 is disposed, and the mold is filled with a softened thermoplastic resin, thereby insulating the member. 34 is formed. Here, in injection molding, a draft may be provided in the concavo-convex portion of the molded product in order to facilitate the release of the mold from the molded product. In general, it is sufficient that the draft angle is about 0.5 ° to 1.0 °. On the other hand, in the insulating member 34 according to the first embodiment, the wall surface 35a of the recess 35 is inclined with respect to the axis of the shaft 7 from the draft of the injection molding. For example, it is inclined by 3 ° or more. The wall surface 35b of the recess 35 on the inner circumferential side rotor 33 side may be inclined to the extent of the injection molding draft or may be inclined more than the draft.

  Next, the operation of the motor 2 according to the first embodiment will be described. In order to explain the operation of the motor 2 of the first embodiment in an easy-to-understand manner, a description will be given in comparison with the comparative example 1 of the motor 2 of the first embodiment. 6 is a cross-sectional view showing the operation of the rotor 51 in the first comparative example, and FIG. 7 is a cross-sectional view showing the operation of the rotor 11 in the first embodiment. First, the rotor 51 in the comparative example 1 is demonstrated. As shown in FIG. 6, the rotor 51 in Comparative Example 1 includes an inner peripheral rotor 33 fastened to the shaft 7, an outer peripheral rotor 32 that constitutes the outer peripheral portion of the rotor 51 and holds the permanent magnet 31, and an inner peripheral An insulating member 52 provided between the side rotor 33 and the outer circumferential side rotor 32 is provided. The insulating member 52 has a recess 53 that is recessed in the axial direction of the shaft 7. The wall surface of the recess 53 is formed substantially parallel to the shaft 7 a of the shaft 7.

  In the rotor 51 in the comparative example 1, the liquid α may be accumulated in the recess 53 due to condensation in the motor main body 2a or entry of moisture from the outside of the motor main body 2a. When the rotor 51 rotates in such a state, centrifugal force F acts on the liquid α along with the rotation. However, since the wall surface of the recess 53 is formed substantially parallel to the shaft 7a of the shaft 7, the direction of the centrifugal force F is substantially perpendicular to the wall surface of the recess 53, and the liquid α is only pressed against the wall surface. Will not be discharged from.

  On the other hand, in the rotor 11 according to the first embodiment, the wall surface 35 a on the outer peripheral side rotor 32 side of the recess 35 is inclined with respect to the shaft 7 a of the shaft 7. For this reason, as shown in FIG. 7, when the rotor 11 rotates, the liquid α accumulated in the recess 35 is discharged. That is, when the rotor 11 rotates, the centrifugal force F acts on the liquid α along with the rotation. The angle between the direction of the centrifugal force F and the wall surface 35a of the recess 35 is an acute angle (an angle smaller than vertical). That is, the wall surface 35 a on the outer peripheral side rotor 32 side of the recess 35 is inclined with respect to the direction of the centrifugal force F. Therefore, the liquid α moves on the wall surface 35a by the action of the centrifugal force F and is discharged out of the recess 35.

  When the shaft 7a of the shaft 7 is inclined with respect to the direction of gravity, the liquid α accumulated in the recess 35 can be discharged even when the rotor 11 does not rotate. For example, when the shaft 7a of the shaft 7 is disposed in the horizontal direction, the liquid α generated in the recess 35 due to condensation or the like is discharged out of the recess 35 due to the inclination of the wall surface 35a or the wall surface 35b of the recess 35.

  As described above, in the first embodiment, it is possible to suppress the liquid α from remaining in the recess 35 formed in the insulating member 34. Therefore, the deterioration of the insulating member 34 of the rotor 11 can be suppressed, and the deterioration of the insulation of the motor 2 can be suppressed. Further, the eccentricity of the rotor 11 caused by the liquid α remaining in the recess 35 formed in the insulating member 34 can be suppressed, and the generation of noise can be suppressed.

Embodiment 2. FIG.
Next, the motor 2 according to Embodiment 2 will be described. FIG. 8 is a cross-sectional view showing the rotor 11 in the second embodiment. In the second embodiment, portions common to the first embodiment are denoted by the same reference numerals, description thereof is omitted, and differences from the first embodiment will be mainly described.

  In the second embodiment, as shown in FIG. 8, a through hole 40 is formed in the bottom surface 35 c of the recess 35 of the insulating member 34 to communicate the insulating member 34 in the axial direction of the shaft 7. With this configuration, in the second embodiment, in addition to the effects obtained in the first embodiment, the liquid accumulated in the recess 35 can be discharged from the through hole 40 even when the rotor 11 does not rotate.

  DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus, 1a outdoor unit, 1b indoor unit, 2 motor, 2a motor main body, 3 base, 3a bending part, 4 terminal cable, 5a 1st bearing, 5b 2nd bearing, 6 bracket, 7 shaft, 7a shaft, 8 flinger, 11 rotor, 12 stator, 13 stator coil, 14 insulator, 15 housing, 15a bearing housing, 16 screw, 17 drain hole, 21 blower, 22 compressor, 23 first heat exchanger, 24 Expansion means, 25 Second heat exchanger, 31 Permanent magnet, 32 Outer rotor, 33 Inner rotor, 34 Insulating member, 35 Recess, 35a Wall surface, 35b Wall surface, 35c Bottom surface, 40 Through hole, 51 Rotor, 52 Insulating member, 53 recess.

Claims (5)

A shaft,
A rotor fixed to the shaft and having a magnet;
A stator that houses the rotor and generates a rotating magnetic field;
With
The rotor is
An inner rotor fastened to the shaft;
An outer peripheral rotor that constitutes an outer peripheral portion of the rotor and holds the magnet;
An insulating member formed by an insulator and provided between the inner circumferential rotor and the outer circumferential rotor;
With
The insulating member is
A recess that is recessed in the axial direction of the shaft is formed,
The motor is characterized in that a wall surface of the recess on the outer rotor side is inclined with respect to the shaft axis. The insulating member is formed by injection molding,
The motor according to claim 1, wherein a wall surface of the concave portion on the outer rotor side is inclined with respect to an axis of the shaft from a draft of the injection molding. The insulating member is
3. The motor according to claim 1, wherein a through hole that communicates the insulating member in the axial direction of the shaft is formed in a bottom surface of the recess. The motor according to any one of claims 1 to 3, wherein the insulating member is made of a thermoplastic resin. An outdoor unit comprising a blower, a compressor, a first heat exchanger, and an expansion unit having the motor according to any one of claims 1 to 4,
An indoor unit comprising a second heat exchanger,
The air conditioner characterized in that the compressor, the first heat exchanger, the expansion means, and the second heat exchanger are connected by piping to form a refrigerant circuit in which the refrigerant circulates.

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