JP2020167845A - Rotator and dynamo-electric motor with the rotator - Google Patents

Abstract

To provide a rotator comprising an insulation member (a coupling part) capable of preventing a thermal breakage while maintaining its strength.SOLUTION: A rotator 3 comprises: an outer peripheral side iron core 32; an inner peripheral side iron core 34; and an insulation member (a coupling part) 33 that couples the outer peripheral side iron core and the inner peripheral side iron core and is formed from an insulation resin. Opposite end sides of an axis O direction of the insulation member 33 are provided with a plurality of first concave parts 331 and 332 arranged in an annular shape; and a plurality of second concave parts 336 and 337 connecting the first concave parts 331 and 332 which are adjacent in a circumferential direction. A depth of each of the second concave parts 336 and 337 is formed shallower than those of the first concave parts 331 and 332.SELECTED DRAWING: Figure 7

Description

The present invention relates to a rotor having an insulating member and an electric motor including the rotor.

As a conventional electric motor, an inner rotor type permanent magnet electric motor in which a rotor having a permanent magnet is rotatably arranged inside a stator that generates a rotating magnetic field is known. This permanent magnet electric motor is used, for example, for rotationally driving a blower fan mounted on an air conditioner.

When this permanent magnet motor is driven by a PWM type inverter that performs high frequency switching, a potential difference (shaft voltage) is generated between the inner ring and the outer ring of the bearing. When this shaft voltage reaches the dielectric breakdown voltage of the oil film inside the bearing, a current flows inside the bearing and causes electrolytic corrosion in the bearing. In order to prevent electrolytic corrosion of this bearing, for example, one provided with a rotor having an insulating member is known (see, for example, Patent Document 1).

The rotor includes, for example, an annular permanent magnet, an annular outer peripheral iron core located on the inner diameter side of the permanent magnet, an annular inner peripheral iron core located on the inner diameter side of the outer peripheral iron core, and an outer peripheral iron core and inner core. It includes an insulating member located between the peripheral iron cores and a shaft fixed to a through hole penetrating in the direction of the central axis of the inner peripheral iron core.

The insulating member of such a rotor is a connecting portion that connects the outer peripheral side iron core and the inner peripheral side iron core, and is formed of, for example, a resin filled between the outer peripheral side iron core and the inner peripheral side iron core.

JP-A-2010-166689

By the way, in the electrolytic corrosion of the bearing described above, when the permanent magnet motor is driven by a PWM type inverter, the neutral point potential of the winding of the stator does not become zero, and a voltage called a common mode voltage is generated. Since this common mode voltage contains a high frequency component due to switching, an axial voltage is generated between the outer ring and the inner ring of the bearing due to the stray capacitance inside the permanent magnet motor.

The common mode voltage is divided as the potential on the inner ring side (shaft side) of the bearing by the capacitance distribution between the stator winding and the shaft and the capacitance between the shaft and the inverter drive circuit board. To. Then, the common mode voltage is divided as a potential on the outer ring side (bracket side) of the bearing by the capacitance between the winding of the stator and the bracket and the capacitance between the bracket and the circuit board for driving the inverter. To. The potential difference between the inner ring side and the outer ring side of this bearing is the shaft voltage.

When the upper limit of the thickness of the insulating member of the rotor is structurally restricted, and even if an insulating resin (for example, PBT resin) is used as the material, the impedance on the rotor side (bearing inner ring side) is low and the shaft voltage is high. In order to suppress the shaft voltage, in the prior art described in Patent Document 1, an air layer or a hole is formed in a part of the insulating member. Since the relative permittivity of air is about 1, the relative permittivity is smaller than that of PBT of about 3 (that is, air has higher insulating property than the insulating resin). Therefore, it is possible to reduce the capacitance of the rotor by providing an air layer and vacancies, and to increase the impedance on the rotor side (bearing inner ring side).

However, when a large number of holes for forming an air layer are formed in the insulating member described in Patent Document 1, the strength of the insulating member may decrease.
On the other hand, thermal stress is generated in the insulating member due to the usage environment of the permanent magnet motor and the heat generated from the stator winding during driving. If the thermal stress is concentrated on a part of the insulating member, there is a concern that the durability of the insulating member may be lowered and cracks or cracks may occur. It was also desired to relieve this thermal stress.

Therefore, an object of the present invention is to provide a rotor having an insulating member capable of preventing thermal cracking while maintaining strength, and an electric motor provided with the rotor.

In order to solve the above problems, one aspect of the rotor of the present invention includes an outer peripheral side iron core, an inner peripheral side iron core, and a connecting portion for connecting the outer peripheral side iron core and the inner peripheral side iron core. The connecting portion is formed of an insulating resin. A plurality of first recesses arranged in an annular shape and a plurality of second recesses connecting the first recesses adjacent to each other in the circumferential direction are provided on both end faces in the axial direction of the connecting portion. The depth of the second recess is formed shallower than the depth of the first recess.

One aspect of the electric motor of the present invention includes a stator fixed to the outer shell of the motor and a rotor arranged on the inner diameter side of the stator. The rotor is made of an insulating resin, which is located between the annular outer peripheral side iron core to which the permanent magnet is fixed, the inner peripheral side iron core located on the inner diameter side of the outer peripheral side iron core, and the outer peripheral side iron core and the inner peripheral side iron core. It is provided with a formed connecting portion and a shaft that is connected to an iron core on the inner peripheral side and is rotatably supported by a bearing on the outer shell of the motor. The rotor is provided with a plurality of first recesses arranged in an annular shape and a plurality of second recesses connecting the first recesses adjacent to each other in the circumferential direction on both end faces in the axial direction of the connecting portion. .. The depth of the second recess is formed shallower than the depth of the first recess.

According to the present invention, it is possible to prevent thermal cracking while maintaining the strength of the connecting portion formed of the insulating resin.

It is a vertical sectional view which shows the permanent magnet electric motor which concerns on this invention. It is a perspective view (a) and a plan view (b) of the outer peripheral side iron core in the rotor of the permanent magnet electric motor which concerns on this invention. It is a perspective view (a) and a plan view (b) of the inner peripheral side iron core in the rotor of the permanent magnet electric motor which concerns on this invention. It is a perspective view (a) and a plan view (b) of the insulating member in the rotor of the permanent magnet electric motor which concerns on this invention. It is a perspective view of the rotor of the permanent magnet electric motor which concerns on this invention. It is a top view of the rotor of FIG. FIG. 6 is a sectional view taken along the line AA of FIG. FIG. 6 is a cross-sectional view taken along the line BB of FIG. FIG. 7 is a sectional view taken along the line CC of FIG. FIG. 7 is a sectional view taken along line DD of FIG. It is a perspective view of the rotor, the shaft and the 2nd bearing of the permanent magnet electric motor which concerns on this invention. It is sectional drawing which shows the permanent magnet electric motor which concerns on this invention. It is a perspective view which shows how the permanent magnet electric motor of FIG. 1 or FIG. 12 is attached to the outdoor unit of an air conditioner. FIG. 1 is a partially enlarged view on the left side of FIG.

Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic and do not necessarily match the actual ones. Therefore, the specific components should be judged in consideration of the following explanation.

Further, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the shape, structure, arrangement, etc. of components. It is not specific to the following. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

The electric motor according to the embodiment of the present invention will be described below.

<Overall configuration of the motor>
1 to 12 are views for explaining the configuration of the electric motor 1 according to the first embodiment. As shown in these figures, the permanent magnet electric motor 1 is, for example, a brushless DC motor. The electric motor 1 is used to rotationally drive the blower fan mounted on the outdoor unit 10 of the air conditioner as shown in FIG. The outdoor unit 10 of the air conditioner includes, for example, a bottom plate 102 screwed to the base 101 of the outdoor unit 10, an upper plate 103 fixed to the upper part of the outdoor unit 10, a pedestal 104 to which the electric motor 1 is attached, and a bottom plate. It is provided with two columns 105 to which the 102, the upper plate 103, and the pedestal 104 are fixed. The electric motor 1 is screwed to the central portion of the pedestal 104.

In the following, an inner rotor type permanent magnet electric motor 1 in which a rotor 3 having a permanent magnet 31 is rotatably arranged on the inner peripheral side of the stator 2 that generates a rotating magnetic field will be described as an example. The permanent magnet electric motor 1 in the present embodiment includes a stator 2, a rotor 3, and a motor outer shell 6.

<Stator and rotor>
The stator 2 includes a stator core 21 having a cylindrical yoke portion and a plurality of teeth portions extending from the yoke portion to the inner diameter side, and a winding 23 wound around the teeth portion via an insulator 22. .. The stator 2 is covered with a motor outer shell 6 made of resin, except for the inner peripheral surface of the stator core 21.

The rotor 3 is rotatably arranged with a predetermined gap on the inner peripheral side of the stator core 21 of the stator 2. The rotor 3 is a surface magnet type in which permanent magnets 31 are arranged in an annular shape on the outer peripheral surface facing the stator core 21. The permanent magnet 31 is fixed to the outer peripheral surface of the outer peripheral side iron core 32, which will be described later. The shaft 35 is connected to the inner peripheral side iron core 34, and the power generated by the rotor 2 is transmitted to the load (blower fan) via the shaft 35 to rotationally drive the blower fan. .. Further, the shaft 35 is supported by the first bearing 41 and the second bearing 42, the first bearing 41 is supported by the first bracket 51, and the second bearing 42 is supported by the second bracket 52, whereby the rotor 3 is supported. Is rotatably supported.

<Bearings and brackets>
The first bearing 41 supports one end side (output side) of the shaft 35 of the rotor 3. The second bearing 42 supports the other end side (counter-output side) of the shaft 35 of the rotor 3. As the first bearing 41 and the second bearing 42, for example, ball bearings are used.

The first bracket 51 is made of metal (steel plate, aluminum, etc.) and is arranged on one end side of the motor outer shell 6, that is, on the output side of the shaft 35. The first bracket 51 has a first bearing accommodating portion 511 for accommodating the first bearing 41, and a flange portion 512 extending around from the open end of the first bearing accommodating portion 511. The first bearing accommodating portion 511 is formed in a cylindrical shape having a bottom portion provided with a through hole for passing the shaft 35, and the flange portion 512 of the first bracket 51 is insert-molded at the time of molding the motor outer shell 6. , It is integrated with the motor outer shell 6.

The outer ring of the first bearing 41 is press-fitted into the inner surface of the first bearing accommodating portion 511, and the output side of the shaft 35 supported by the inner ring of the first bearing 41 is formed in the center of the bottom portion of the first bearing accommodating portion 511. It protrudes to the outside from the through hole.

The second bracket 52 is made of metal (steel plate, aluminum, etc.) and is fixed to the other end side of the motor outer shell 6, that is, the counter-output side of the shaft 35. The second bracket 52 includes a disc-shaped bracket main body 521, an outer edge portion 520 that closes an end portion of the motor outer shell 6 on the opposite output side, and a second bearing accommodating portion 522 for accommodating the second bearing 42. And have.

The outer edge 520 of the second bracket 52 is screwed to the end of the motor outer shell 6 on the opposite output side. The second bearing accommodating portion 522 is formed as a hole having a circular bottom surface recessed from the motor outer shell 6 side (output side) in the central portion of the bracket main body portion 521.

The first bearing 41 is housed in the first bearing accommodating portion 511 provided in the first bracket 51, and the second bearing 42 is accommodated in the second bearing accommodating portion 522 provided in the second bracket 52. The first bearing 41 and the first bearing accommodating portion 511, and the second bearing 42 and the second bearing accommodating portion 522 are electrically conductive, respectively.

The second bracket 52 integrally includes a heat sink between the second bearing accommodating portion 522 and the outer edge portion 520 in the radial direction. As a result, the space of the electric motor 1 can be saved.
The second bracket is provided with heat radiation fins 523 erected outward on the opposite output side of the shaft 35 as a heat sink, and is a circuit board 72 for controlling the electric motor 1 via a heat transfer member 71 (particularly, The heat from the electronic component 721) mounted on the circuit board 72 is efficiently dissipated by the heat radiating fins 523.

<Structure, action and effect of rotor according to the present invention>
Next, in the permanent magnet electric motor 1 of the present embodiment, the structure of the rotor 3 according to the present invention, its action and effect will be described with reference to FIGS. 2 to 10.
In the permanent magnet electric motor 1, as shown in FIG. 1, an insulating member 33 is provided in a part of the rotor 3 in order to prevent electrolytic corrosion in the first bearing 41 and the second bearing 42. Hereinafter, a specific configuration of the rotor 3 will be described.

As shown in FIGS. 1 to 11, the rotor 3 has a permanent magnet 31, an outer peripheral side iron core 32, an insulating member (connecting portion) 33, and an inner peripheral side iron core 34 from the outer diameter side to the inner diameter side. And the shaft 35 is provided.

As shown in FIGS. 1, 11 and 12, the permanent magnet 31 is annular with a plurality of (for example, 8 or 10) permanent magnet pieces 311 so that the north and south poles appear alternately at equal intervals in the circumferential direction. Is formed in. As the permanent magnet 31, a plastic magnet formed in an annular shape by solidifying the magnet powder with a resin may be used.

The outer peripheral side iron core 32 is formed in an annular shape as shown in FIG. 2, and is located on the inner diameter side of the permanent magnet 31 as shown in FIGS. 11 and 12. The outer peripheral side iron core 32 is recessed from the inner peripheral surface (see FIG. 2) to the outer diameter side in order to secure the function of preventing rotation with the insulating member 33 described later, and the direction of the axis O of the rotor 3 (hereinafter, hereinafter, It is provided with a plurality of (for example, five in the circumferential direction) inner peripheral side recesses 321 extending in the axial direction. That is, the inner peripheral side recess 321 is a key groove that prevents rotation of the insulating member 33 (a groove that prevents slipping between the insulating member 33. The key groove improves the fastening force between the members and improves power transmission efficiency. Can be enhanced). Further, the outer peripheral side iron core 32 is provided with a plurality of outer peripheral side protrusions 322 (for example, 10 in the circumferential direction) protruding from the outer peripheral surface to the outer diameter side in order to position the permanent magnet 31.

The plurality of inner peripheral side recesses 321 extend in the axial direction from the end surface of the insulating member 33 and are arranged at equal intervals in the circumferential direction. In the present embodiment, two inner peripheral side recesses 321 are arranged so as to extend from both ends of the outer peripheral side iron core 32 in the axial direction. As a result, the outer peripheral side iron core 32 has a partition wall 323 (retaining portion) between the inner peripheral side recesses 321 adjacent to each other in the axial direction, and the partition wall 323 causes the insulating member 33 (connecting portion) (in both axial directions). ) Can be prevented from coming off.

The plurality of outer peripheral protrusions 322 extend in the axial direction and are arranged at equal intervals in the circumferential direction. Further, each outer peripheral side protrusion 322 is arranged so as to extend from one end to the other end of the outer peripheral side iron core 32 in the axial direction.

The inner peripheral side iron core 34 is formed in an annular shape as shown in FIG. 3, and is located on the inner diameter side of the outer peripheral side iron core 32 as shown in FIGS. 5 to 10. The inner peripheral side iron core 34 is recessed from the outer peripheral surface (see FIG. 3) toward the inner diameter side and extends in the axial direction (for example, in the circumferential direction) in order to secure the function of preventing rotation with the insulating member 33 described later. 6) outer peripheral side recesses 341 are provided. That is, the outer peripheral side recess 341 functions as a key groove for preventing rotation of the insulating member 33.

The plurality of outer peripheral side recesses 341 extend in the axial direction and are arranged at equal intervals in the circumferential direction. In the present embodiment, the outer peripheral side recess 341 is partitioned by a partition wall 344 (retaining portion) arranged at the center in the axial direction. Therefore, two outer peripheral side recesses 341 are arranged so as to extend from both end portions of the inner peripheral side iron core 34. As a result, the inner peripheral side iron core 34 has a partition wall 344 between the outer peripheral side recesses 341 adjacent to each other in the axial direction, and the partition wall 344 (removal portion) of the insulating member 33 (connecting portion) (in both axial directions). ) Can be prevented from coming off.

A through hole 343 penetrating in the axial direction is provided at the center of the inner peripheral side iron core 34. A shaft 35 is passed through a through hole 343 of the inner peripheral side iron core 34, and the shaft 35 and the inner peripheral side iron core 34 are connected to each other. The inner peripheral side iron core 34 may be provided with a plurality of through holes 342 for lightening the weight between the through hole 343 and the outer peripheral surface of the inner peripheral side iron core 34. These plurality of through holes 342 are arranged at equal intervals in the circumferential direction so that the shape of the inner peripheral side iron core 34 in which the through holes 342 are formed becomes a spoke shape when viewed from the axial direction.

The insulating member 33 is made of a dielectric resin such as PBT (polybutylene terephthalate) or PET (polyethylene terephthalate), and is located between the outer peripheral side iron core 32 and the inner peripheral side iron core 34. The insulating member 33 is integrally formed with the outer peripheral side iron core 32 and the inner peripheral side iron core 34 by insert molding in which a resin is filled between the outer peripheral side iron core 32 and the inner peripheral side iron core 34. The insulating member 33 has a small capacitance between the outer peripheral side iron core 32 and the inner peripheral side iron core 34 (a part of the capacitance between the winding 23 of the stator 2 and the shaft 35). By lowering the potential on the inner ring side of the 1st bearing 41 and the 2nd bearing 42, the potential difference between the inner ring side and the outer ring side is adjusted to be small.

As shown in FIG. 4, the insulating member 33 includes (plural) outer peripheral side convex portions 338 on the outer peripheral surface that engage with the inner peripheral side concave portion 321 of the outer peripheral side iron core 32 described above. Further, the insulating member 33 includes (plural) inner peripheral side convex portions 339 that engage with the outer peripheral side concave portions 341 of the inner peripheral side iron core 34 on the inner peripheral surface.

Here, an engaging portion (inner peripheral side recess 321 and outer peripheral side recess 321) provided between the outer peripheral side iron core 32 and the insulating member (connecting portion) 33 to prevent rotation between the outer peripheral side iron core 32 and the insulating member 33. The side convex portion 338) is used as the first concave-convex engaging portion, and is provided between the insulating member 33 and the inner peripheral side iron core 34 to prevent rotation between the insulating member 33 and the inner peripheral side iron core 34. The joint portion (inner peripheral side convex portion 339 and outer peripheral side concave portion 341) is referred to as a second uneven engagement portion. As described above, in the present embodiment, the outer peripheral side iron core 32 and the inner peripheral side iron core 34 are formed with recesses of the concave-convex engaging portion (the first concave-convex engaging portion and the second concave-convex engaging portion) to insulate. An example is shown in which a convex portion of the concave-convex engaging portion is formed on the member (connecting portion) 33.

Whether the concave portion and the convex portion of the concave-convex engaging portion are arranged on the rotor core (32, 34) or the insulating member 33 may be reversed from the above-mentioned case. For example, the convex portion of the concave-convex engaging portion may be provided on the outer peripheral side iron core 32 and the inner peripheral side iron core 34, and the concave portion of the concave-convex engaging portion may be provided on the insulating member 33.

As shown in FIGS. 2 to 4 and 7 and 8, the first concave-convex engaging portions 321 and 338 and the second concave-convex engaging portions 339 and 341 have inner peripheral side recesses 321 adjacent to each other in the axial direction. Since the partition wall 323 (retaining portion) is formed between the two, and the partition wall 344 (removing portion) is formed between the outer peripheral side recesses 341 adjacent to each other in the axial direction, the outer peripheral side iron core 32 and the inner peripheral side iron core 34 are formed. The insulating member 33 can be prevented from coming off. Therefore, as described above, the first concavo-convex engaging portion 321 and 338 and the second concavo-convex engaging portion 339 and 341 can have both a rotation preventing function and a retaining function by engaging each of the unevenness.

Here, consider the shear stress received by the concave-convex engaging portion that functions as a key (a mechanical element that fastens a rotating body to a shaft) when the rotor 3 rotates. Assuming that the position where the concave-convex engaging portion (key) is arranged is the position of the radius r [m] from the central axis O on the shaft for transmitting the torque having a size of T [Nm], the shape of the concave-convex engaging portion. The shear stress τ [Pa] acting on the concave-convex engaging portion when it is assumed that is uniform can be expressed by τ = α × T / r (α: proportionality constant). Further, the radial position (that is, the inner diameter of the outer peripheral side iron core 32) r1 of the first concave-convex engaging portion provided between the outer peripheral side iron core 32 and the insulating member 33, and the insulating member 33 and the inner peripheral side iron core 34. Comparing with the radial position (that is, the outer diameter of the inner peripheral side iron core 34) r2 of the second uneven engagement portion provided between the two, r1> r2 always holds. Further, it can be considered that the torque transmitted between the outer peripheral side iron core 32 and the insulating member 33 and the torque transmitted between the insulating member 33 and the inner peripheral side iron core 34 are equal. Therefore, it is insulated between the members on the inner diameter side (insulated from the inner peripheral side iron core 34) than the shear stress τ1 acting between the members on the outer diameter side (the first uneven engagement portion between the outer peripheral side iron core 32 and the insulating member 33). The shear stress τ2 acting on the second concave-convex engaging portion between the members 33 is always larger (that is, τ1 <τ2 always holds). Therefore, by increasing the number of the second concave-convex engaging portions 339 and 341 in the circumferential direction to be larger than the number of the first concave-convex engaging portions 321 and 338 in the circumferential direction, they are provided between the members on the inner diameter side. The shear stress acting on the individual first uneven engaging portions 321 and 338 can be reduced, and the detent of the insulating member 33 can be further strengthened.

The shaft 35 is passed through a through hole 343 provided in the inner peripheral side iron core 34, and is fixed to the inner peripheral side iron core 34 by press fitting or caulking.

Since the permanent magnet motor 1 used to rotationally drive the blower fan mounted on the air conditioner is driven by a PWM inverter, the neutral point potential of the winding does not become zero, and the common mode voltage is used. A voltage called is generated. Due to this common mode voltage, a potential difference (shaft voltage) is generated between the outer ring and the inner ring of the first bearing 41 and the second bearing 42 due to the stray capacitance inside the permanent magnet motor 1. When this shaft voltage reaches the dielectric breakdown voltage of the oil film inside the bearing, a current flows inside the bearing and causes electrolytic corrosion inside the bearing.

In the rotor 3, the insulating member 33 is formed in a cylindrical shape as shown in FIGS. 4 to 10, and in order to reduce the capacitance of the rotor 3, one end in the axial direction is in the first axial direction. A hole 331 is formed, and a second axial hole 332 for reducing the capacitance of the rotor 3 is similarly formed at the other end in the axial direction. A plurality (for example, 10) of these first axial holes 331 and the second axial holes 332 are formed at equal intervals in the circumferential direction. A partition wall 334 is uniformly formed between each of the plurality of first axial holes 331 and between each of the plurality of second axial holes 332, and the first axial holes adjacent to each other in the circumferential direction. The 331s and the second axial holes 332 adjacent to each other in the circumferential direction are separated from each other. Here, the plan view and the bottom view of the rotor 3 are the same. The partition wall 334 enhances the mechanical strength of the insulating member 33 (connecting portion), and when the rotor 3 rotates, the power of the rotational motion is sufficiently transmitted between the inner peripheral side iron core 34 and the outer peripheral side iron core 32. Can be done.

Further, as shown in FIG. 7, the first axial hole 331 and the second axial hole 332 face each other in the axial direction, and the center of the insulating member 33 in the axial direction (the first axis facing the axial direction). (Between the direction hole 331 and the second axial direction hole 332), a wall portion 333 is provided so as to divide the holes so that the depths of the holes are the same. The wall portion 333 enhances the mechanical strength of the insulating member 33 (connecting portion), and when the rotor 3 rotates, the power of the rotational movement is sufficiently transmitted between the inner peripheral side iron core 34 and the outer peripheral side iron core 32. be able to. Further, by providing the wall portion 333, a bottom portion 335c of the first axial direction hole 331 is formed on one end side of the wall portion 333, and a bottom portion of the second axial direction hole 332 is formed on the other end side of the wall portion 333. 335c is formed. A side wall 335a and a side wall 335b are formed along the axial direction from the bottom 335c of each of the first axial hole 331 and the second axial hole 332.

As described above, the first axial hole 331 and the second axial hole 332 have a structure having a depth in the direction along the axial direction from both end faces by forming the wall portion 333. Further, as shown in FIGS. 6 to 9, the first axial hole 331 and the second axial hole 332 are formed so that the end face shape seen from the axial direction is an arc shape along the circumferential direction, respectively. Are formed at equal intervals (for example, 10 in the circumferential direction).

Here, for example, when the first axial hole 331 and the second axial hole 332 are formed with respect to the rotor 3 having a small radius and a thick axial direction, the radius of the rotor 3 is small, so that the first axial direction is formed. The radial length (width) R of the hole 331 and the second axial hole 332 is also limited to be small.

Further, since the insulating member 33 in the present embodiment is formed by integrally molding a dielectric resin such as PBT or PET together with the outer peripheral side iron core 32 and the inner peripheral side iron core 34, the first axial direction hole 331 and the first Considering the draft of the mold at the time of molding the biaxial hole 332, the length (width) R in the radial direction of the first axial hole 331 and the second axial hole 332 cannot be increased.

In order to reduce the capacitance of the rotor 3, for example, it is conceivable to increase the depth of the first axial hole 331 and the second axial hole 332. However, if the depth of the first axial hole 331 and the second axial hole 332 is made too deep, the thickness of the wall portion 333 that separates the first axial hole 331 and the second axial hole 332 becomes thin, and insulation is provided. Since the mechanical strength of the member 33 is lowered, a wall portion 333 having an appropriate thickness is required to secure the mechanical strength. Here, in order to increase the mechanical strength, the axial thickness of the partition wall 323 (retaining portion) of the outer peripheral side iron core 32 and the axial thickness of the partition wall 344 (removing portion) of the inner peripheral side iron core 34 are set to the wall portion 333. Is approximately equal to the (axial) thickness of.

Further, in the present embodiment, as described above, the first axial hole 331 and the second axial hole 332 have a circumferential end face shape when viewed from the axial direction, as shown in FIGS. 6 to 9. It is formed in an arc shape along. That is, by making the length (width) R in the radial direction of the first axial hole 331 and the second axial hole 332 constant in the circumferential direction, the size of the hole can be increased in a limited space. Moreover, the capacitance of the rotor 3 can be reduced.

As described above, the size and shape of the first axial hole 331 and the second axial hole 332 are determined in consideration of both the reduction of the capacitance of the rotor 3 and the securing of mechanical strength.

By the way, in general, the coefficient of linear expansion of resin is 10 times or more larger than the coefficient of linear expansion of metal. Therefore, in the resin insulating member 33, the amount of expansion when the temperature rises and the amount of contraction when the temperature drops are larger than those of the metal outer peripheral side iron core 32 and the inner peripheral side iron core 34.

As shown in FIGS. 6 to 8, the side walls 335a and 335b of the insulating member 33 are thin in the radial direction and thick in the axial direction. Therefore, the amount of expansion and contraction of the side walls 335a and 335b of the insulating member 33 is larger in the axial direction than in the radial direction.

Further, the amount of expansion and contraction of the wall portion 333 and the partition wall 334 of the insulating member 33 are divided into a radial component and an axial component, but the radial expansion and contraction are performed on the outer peripheral side iron core 32 and the inner peripheral side. Since it is regulated by the iron core 34, the amount of expansion and contraction in the axial direction tends to be larger than the amount of expansion and contraction in the radial direction.

Here, the insulating member 33 sandwiched between the outer peripheral side iron core 32 and the inner peripheral side iron core 34 shown in FIGS. 7 and 8 is displaced in the axial direction (change in position) due to expansion or contraction. It varies depending on where it was in the axial direction before it contracted. That is, since the insulating member 33 expands or contracts in both axial directions with the central portion in the axial direction as a boundary, the displacement becomes larger as the insulating member 33 is farther from the central portion in the axial direction. For example, the central portion in the axial direction (near the wall portion 333) has almost no axial displacement before and after expansion. On the other hand, the axial end (near the end 335d) has a large axial displacement before and after expansion. Since the insulating member 33 has a small radial width and is restricted from expanding and contracting in the radial direction, the displacement in the radial direction due to the expansion and contraction is almost the same regardless of the axial position. Absent.

Further, in the insulating member 33, thermal stress is likely to be concentrated in a portion where expansion or contraction in the radial direction is regulated by the outer peripheral side iron core 32 and the inner peripheral side iron core 34. Therefore, in the present embodiment, the thermal stress is concentrated on the wall portion 333 and the partition wall 334 of the insulating member 33.

As described above, when considering the expansion due to the temperature rise of the side walls 335a, 335b, the wall portion 333, and the partition wall 334 of the insulating member 33, the amount of expansion in the axial direction tends to be larger than that in the radial direction. , Thermal stress is particularly concentrated in places where expansion is regulated or where the amount of displacement is large.

Then, due to the influence of the expansion of the insulating member 33, the thermal stress is concentrated on the portion where the wall portion 333 and the side walls 335a and 335b shown in FIG. 7 intersect, but the first axial direction hole 331 and the second axial direction hole 332 Since the (first recess) is provided, the force can be released to the first recess side, and the thermal stress can be relaxed.
In addition, due to the influence of the expansion of the insulating member 33, the thermal stress is concentrated on the axial ends of the side walls 335a and 335b, but the above-mentioned first recess is provided, so that the first recess side The force can be released and the thermal stress can be relieved.

On the other hand, in the partition wall 334 shown in FIG. 8, the expansion in the radial direction is restricted to the outer peripheral side iron core 32 and the inner peripheral side iron core 34, and the displacement amount due to the expansion near the axial end portion 335d becomes particularly large. .. Therefore, due to the influence of the expansion of the insulating member 33, the vicinity of the axial end portion 335d of the insulating member 33 that covers the inner and outer edges of the outer peripheral side iron core 32 and the inner peripheral side iron core 34 is particularly liable to crack.

Therefore, in order to prevent the above-mentioned thermal cracking, the insulating member 33 is provided between the first axial holes 331 and between the second axial holes 332, which are arranged in an annular shape, as shown in FIGS. 6 and 8. A third axial hole 336 is formed at one end in the axial direction, and a fourth axial hole 337 is similarly formed at the other end in the axial direction at a position between the two. The third axial hole 336 and the fourth axial hole 337 (second recesses 336 and 337) are the same as the first axial hole 331 and the second axial hole 332 (first recesses 331 and 332). It is formed on the circumference and is arranged in an annular shape.
Further, a plurality of third axial hole 336 and fourth axial hole 337 (second concave portion) are provided at equal intervals in the circumferential direction, similarly to the first axial hole 331 and the second axial hole 332 (for example,). 10) are formed. Further, each of the third axial hole 336 and the fourth axial hole 337 is arranged so as to overlap the partition wall 334 described above in the axial direction. Further, as shown in FIGS. 6 to 9, the third axial hole 336 and the fourth axial hole 337 are formed so that the end face shape when viewed from the axial direction is an arc shape along the circumferential direction. Further, the third axial hole 336 and the fourth axial hole 337 are continuous with the first axial hole 331 and the second axial hole 332, so that the insulating member 33 has an annular recess on both end surfaces in the axial direction. A groove is formed. That is, when the first axial hole 331 and the second axial hole 332 are the first recesses, and the third axial hole 336 and the fourth axial hole 337 are the second recesses, the insulating member (connecting portion). An annular concave groove portions (331, 336, and 332, 337) formed in an annular shape are provided on both end faces in the axial direction of the 33. By making the length (width) R in the radial direction on both end faces constant in the circumferential direction, the annular concave groove portion can uniformly disperse the force in the circumferential direction.

In particular, the bottom portion (position of the axial end portion of the partition wall 334) of the second recess (third axial hole 336, fourth axial hole 337) is a rotor core (outer peripheral side iron core 32 and inner peripheral side). It has been confirmed that the concentration of thermal stress in the insulating member 33 is suppressed when the iron core 34) is formed so as to be closer to the central portion in the axial direction than the end face in the axial direction. Based on this, in the present embodiment, the depth of the third axial hole 336 and the fourth axial hole 337 is formed so as to be 5.5 mm from the axial end face of the insulating member 33. On the other hand, the depth of the first axial hole 331 and the second axial hole 332 is formed so as to be 16.5 mm from the axial end face of the insulating member 33.

Here, as shown in FIGS. 14 and 1, the depths of the first axial hole 331 and the second axial hole 332 (the depth of the first recess) are M [mm], and the third axial hole. The depth of the 336 and the fourth axial hole 337 (the depth of the second recess) is S [mm], and the axial length (core product thickness) of the outer peripheral side iron core 32 and the inner peripheral side iron core 34 is L [mm]. ], The axial thickness (central wall thickness) of the wall portion 333 is C [mm].
At this time, as can be seen from FIG. 14, the condition that the bottom portion of the second recess (336, 337) is on the axially central portion side of the axial end face of the rotor cores (32, 34) is known.
2M + C-2S <L
Is to be. It is desirable that the rotor 3 is designed so as to satisfy this conditional expression. That is, by satisfying this conditional expression, it is possible to more reliably prevent thermal cracking of the insulating member 33. 2M + C corresponds to the axial length of the insulating member 33.

Therefore, by forming the third axial hole 336 and the fourth axial hole 337, which are the second recesses, the region where the insulating member 33 has a large axial length is reduced, and the total volume of the insulating member 33 is reduced. The amount of expansion and contraction of the insulating member 33 in the axial direction can be reduced. Further, since the second recesses 336 and 337 are provided, the force applied to the vicinity of the axial end portion 335d can be released to the second recess side, the thermal stress is relaxed, and the thermal stress is concentrated. Can be suppressed. Therefore, it is possible to suppress a decrease in durability due to the concentration of thermal stress of the insulating member 33, and it is possible to suppress the occurrence of thermal cracks and cracks and extend the life.

That is, as shown in FIGS. 5 to 8, the plurality of third axial holes 336 (second recesses) are the plurality of first axial holes 331 (first recesses) arranged in an annular shape. It is arranged between the holes and is formed so as to connect the first axial holes 331 adjacent to each other in the circumferential direction. Similarly, the plurality of fourth axial holes 337 (second recesses) are arranged between the plurality of second axial holes 332 (first recesses) arranged in an annular shape and have a circumference. It is formed so as to connect the second axial holes 332 adjacent to each other in the direction. As a result, the concentration of thermal stress can be suppressed.

Further, the depths of the third axial hole 336 and the fourth axial hole 337 are formed to be smaller (shallow) than the depths of the first axial hole 331 and the second axial hole 332. As a result, a partition wall 334 that partitions the second axial holes 332 between the first axial holes 331 adjacent to each other in the circumferential direction and between the second axial holes 332 adjacent to each other in the circumferential direction is provided. It can be formed, and the strength of the insulating member 33 (connecting portion) can be increased.

Further, when the first axial hole 331 and the second axial hole 332 are used as the first recess and the third axial hole 336 and the fourth axial hole 337 are used as the second recess, the insulating member (connecting portion). An annular concave groove portions (331, 336, and 332, 337) formed in an annular shape are provided on both end faces in the axial direction of the 33. As a result, at the axial end of the insulating member 33, the side walls 335a and 335b can expand toward the annular concave groove in the radial direction, so that the influence of thermal stress is further mitigated and the insulating member 33 is thermally cracked. Can be prevented.

In the above description, a case where the insulating member 33 thermally expands due to heat generated by the winding 23 of the stator 2 in the usage environment and the driving state of the permanent magnet electric motor 1 has been described. Not only that, but also around the bottom of the first axial hole 331 and the second axial hole 332 and around the end of the insulating member 33 during heat shrinkage when the temperature drops depending on the usage environment and driving state of the permanent magnet motor 1. The concentration of thermal stress can be relaxed.
In the present embodiment, in order to suppress thermal stress, the insulating member 33 is provided with the first recesses 331 and 332 and the second recesses 336 and 337, and the thickness (and resin) of the insulating member 33 in the axial direction is provided. The volume) can be reduced, the stresses during thermal expansion and contraction can be reduced, and thermal cracking of the insulating member 33 can be prevented.

Therefore, in order to prevent electrolytic corrosion of the first bearing 41 and the second bearing 42 that support the shaft 35, the insulating member 33 is arranged on the rotor 3, and the insulating member 33 has the first axial hole 331 and the second axial direction. When the hole 332 and the third axial hole 336 and the fourth axial hole 337 are formed, the concentration of thermal stress generated in the insulating member 33, which is a problem when the rotor 3 having a small diameter is manufactured, is alleviated. Can be made to.
As a result, it is possible to manufacture a small rotor 3 that maintains the connection strength between the outer peripheral side iron core 32 and the inner peripheral side iron core 34, increases the impedance between them, and reduces the capacitance of the rotor 3. it can. Further, the permanent magnet electric motor 1 provided with the rotor 3 can also be miniaturized.

Here, in order to adjust the capacitance and durability of at least one of the first axial hole 331 and the second axial hole 332, or at least one of the third axial hole 336 and the fourth axial hole 337. Members (resin, metal, etc.) may be attached.

Further, in each of the above embodiments, the end face shapes of the first axial hole 331 and the second axial hole 332 and the third axial hole 336 and the fourth axial hole 337 when viewed from the axial direction are circular. Although the case where the shape is formed in an arc shape along the circumferential direction has been described, the shape of each axial hole is not limited to this. Further, the number of the first axial hole 331 and the second axial hole 332 and the number of each of the third axial hole 336 and the fourth axial hole 337 are not limited to 10, but can be any number. can do.

Further, in each of the above embodiments, the first axial hole 331 and the second axial hole 332 are formed symmetrically with respect to the wall portion 333, but the present invention is not limited to this, and the first axial direction is not limited to this. The hole 331 and the second axial hole 332 may be formed in an asymmetrical shape (for example, C-shaped when viewed from the axial direction) with respect to the wall portion 333. Similarly, the third axial hole 336 and the fourth axial hole 337 may be formed in an asymmetrical shape (for example, C-shaped when viewed from the axial direction) with respect to the wall portion 333.

Further, in each of the above embodiments, the case where the present invention is applied to the surface magnet type rotor 3 in which the permanent magnet 31 is arranged on the outer peripheral surface of the outer peripheral side iron core 32 has been described, but the present invention is not limited thereto. The present invention can also be applied to an embedded magnet type rotor in which a slot extending in the axial direction is formed at a chord position with respect to the outer peripheral surface of the outer peripheral side iron core 32 and a permanent magnet is arranged in this slot.

1 ... Permanent magnet motor 2 ... Stator 10 ... Outdoor unit 101 ... Base 102 ... Bottom plate 103 ... Top plate 104 ... Side plate 21 ... Stator Iron core 22 ... Insulator 23 ... Winding 3 ... Rotor 31 ... Permanent magnet 311 ... Permanent magnet One piece 32 ... Outer peripheral side iron core 321 ... Inner peripheral side concave portion (first uneven engagement portion)
323 ... Septum (removal part)
33 ... Insulation member (connecting part)
33a ... One end surface 33b ... The other end surface 331 ... First axial hole (first recess)
332 ... 2nd axial hole (1st recess)
333 ... Wall 334 ... Partition 335a, 335b ... Side wall 335c ... Bottom 335d ... End 336 ... Third axial hole (second recess)
337 ... Fourth axial hole (second recess)
338 ... Convex portion on the outer peripheral side (first uneven engagement portion)
339 ... Inner peripheral side convex portion (second uneven engagement portion)
34 ... Inner peripheral side iron core 341 ... Outer peripheral side concave portion (second uneven engagement portion)
343 ... Through hole 344 ... Partition wall (retaining part)
35 ... Shaft 41 ... 1st bearing 42 ... 2nd bearing 51 ... 1st bracket 511 ... 1st bearing accommodating part 512 ... Flange part 52 ... 2nd bracket 521 ... Bracket body part 522 ... 2nd bearing accommodating part 523 ... Heat transfer fin 6 ... Motor outer shell 71 ... Heat transfer member 72 ... Circuit board O ... Central axis

Claims (8)

It is provided with an outer peripheral side iron core, an inner peripheral side iron core, and a connecting portion for connecting the outer peripheral side iron core and the inner peripheral side iron core.
The connecting portion is made of an insulating resin.
A plurality of first recesses arranged in an annular shape and a plurality of second recesses connecting the first recesses adjacent to each other in the circumferential direction are provided on both end faces in the axial direction of the connecting portion. ,
The rotor formed so that the depth of the second recess is shallower than the depth of the first recess. The rotor according to claim 1.
The connecting portion is provided with a plurality of partition walls that partition the first recesses adjacent to each other in the circumferential direction.
The second recess and the partition wall are rotors arranged so as to overlap each other in the axial direction. The rotor according to claim 1 or 2.
A rotor in which an annular recessed groove portion is formed on both end faces in the axial direction of the connecting portion by connecting the plurality of the first recesses and the plurality of the second recesses. The rotor according to any one of claims 1 to 3.
A first concavo-convex engaging portion provided between the outer peripheral side iron core and the connecting portion and for preventing rotation between the outer peripheral side iron core and the connecting portion,
A second concave-convex engaging portion provided between the connecting portion and the inner peripheral side iron core to prevent rotation between the connecting portion and the inner peripheral side iron core,
A rotor equipped with. The rotor according to claim 4.
At least one of the first concavo-convex engaging portions adjacent to each other in the axial direction and the second concavo-convex engaging portions adjacent to the axial direction is the outer peripheral side iron core or the said. A rotor in which a retaining portion is formed to prevent the connecting portion from coming off from the inner peripheral side iron core. The rotor according to claim 4 or 5.
The number of the second concave-convex engaging portions is larger than the number of the first concave-convex engaging portions of the rotor. The rotor according to any one of claims 1 to 6.
The insulating resin is a rotor that is polybutylene terephthalate (PBT) or PET (polyethylene terephthalate). An electric motor including a stator fixed to the outer shell of the motor and a rotor arranged on the inner peripheral side of the stator.
The rotor is located between the annular outer peripheral side iron core to which the permanent magnet is fixed, the inner peripheral side iron core located on the inner peripheral side of the outer peripheral side iron core, and the outer peripheral side iron core and the inner peripheral side iron core. A connecting portion made of an insulating resin and a shaft connected to the inner peripheral side iron core and rotatably supported by a bearing on the outer shell of the motor are provided.
A plurality of first recesses arranged in an annular shape and a plurality of second recesses connecting the first recesses adjacent to each other in the circumferential direction are provided on both end faces in the axial direction of the connecting portion.
An electric motor having a rotor formed so that the depth of the second recess is shallower than the depth of the first recess.

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