WO2023148953A1

WO2023148953A1 - Rotor, electric motor, air blower, air conditioning device, and method for producing electric motor

Info

Publication number: WO2023148953A1
Application number: PCT/JP2022/004601
Authority: WO
Inventors: 貴也下川; 隆徳渡邉; 和慶土田; 祐輔前島
Original assignee: 三菱電機株式会社
Priority date: 2022-02-07
Filing date: 2022-02-07
Publication date: 2023-08-10
Also published as: JPWO2023148953A1

Abstract

This rotor has a rotating shaft to which a bearing is attached, a rotor core fixed to the rotating shaft, and a permanent magnet fixed to the rotor core. The rotor core has a hole section extending in the axial direction of the rotating shaft. The distance Lm from the central axis of the rotating shaft to the permanent magnet, the distance Ls from the central axis to the hole section, and the distance Lb from the central axis to the outer circumference of a bearing satisfy Lm > Ls > Lb.

Description

Rotor, electric motor, blower, air conditioner, and electric motor manufacturing method

The present disclosure relates to rotors, electric motors, blowers, air conditioners, and electric motor manufacturing methods.

An electric motor has a rotor fixed to a rotating shaft and an annular stator surrounding the rotor (see Patent Document 1, for example). When assembling the electric motor, one end of the rotating shaft is gripped and the rotor is inserted inside the stator.

International publication WO2020/003341 (see FIG. 2)

However, when inserting the rotor into the stator, a magnetic attraction acts between them. At the end of the rotating shaft opposite the gripped side, the rotor contacts the stator, which can cause deformation or wear of the rotor and stator.

The present disclosure has been made to solve the above problems, and aims to enable the rotor to be inserted without contacting the stator.

The rotor of the present disclosure has a rotating shaft to which bearings are attached, a rotor core fixed to the rotating shaft, and permanent magnets fixed to the rotor core. The rotor core has a hole extending in the axial direction of the rotating shaft. The distance Lm from the central axis of the rotating shaft to the permanent magnet, the distance Ls from the central axis to the hole, and the distance Lb from the central axis to the outer circumference of the bearing satisfy Lm>Ls>Lb.

A method of manufacturing an electric motor according to the present disclosure includes steps of assembling a rotor having a rotating shaft, a rotor core fixed to the rotating shaft and having a hole in the axial direction of the rotating shaft, and permanent magnets attached to the rotor core; The method includes a step of assembling a stator, a step of attaching a bearing to the rotating shaft of the rotor, and a step of inserting the rotor inside the stator while inserting the shaft portion of the jig into the hole to hold the rotor.

According to the present disclosure, since the distances Lm and Ls satisfy Lm>Ls, the hole is formed at a position that does not block the magnetic path in the rotor core as much as possible. Further, since the distances Ls and Lb satisfy Ls>Lb, the rotor can be inserted into the stator while being held by a jig inserted into the hole. Therefore, the rotor can be inserted without contacting the stator.

1 is a longitudinal sectional view showing the electric motor of Embodiment 1; FIG. 2 is a cross-sectional view showing the electric motor of Embodiment 1; FIG. 2 is a cross-sectional view showing the rotor of Embodiment 1; FIG. 2 is a schematic diagram showing a rotor and bearings of the electric motor of Embodiment 1; FIG. 4 is a flow chart showing a method for manufacturing the electric motor of Embodiment 1. FIG. FIG. 4 is a schematic diagram showing a method of inserting the rotor into the stator according to the first embodiment; FIG. 8 is a schematic diagram showing another example of a method of inserting the rotor into the stator of Modification 1; FIG. 11 is a cross-sectional view showing a rotor of modification 2; FIG. 10 is a vertical cross-sectional view showing a rotor of Embodiment 2; FIG. 10 is a cross-sectional view of the rotor of Embodiment 2 taken along the line XX in FIG. 9; FIG. 10 is a cross-sectional view of the rotor of Embodiment 2 taken along line XI-XI in FIG. 9; FIG. 8 is a schematic diagram showing a method of inserting the rotor into the stator according to the second embodiment; FIG. 11 is a cross-sectional view showing a rotor according to Embodiment 3; FIG. 11 is a cross-sectional view showing a rotor according to Embodiment 3; It is the figure (A) which shows the air conditioning apparatus to which the electric motor of each embodiment and the modification is applicable, and the figure (B) which shows its outdoor unit.

Embodiment 1.
<Overall Configuration of Electric Motor 1>
An electric motor according to Embodiment 1 will be described. FIG. 1 is a longitudinal sectional view showing an electric motor 1 according to Embodiment 1. FIG. A motor 1 is a synchronous motor, and is used, for example, as a blower of an air conditioner 500 (FIG. 15(A)).

The electric motor 1 includes a rotor 2 having a rotating shaft 10 , a stator 3 surrounding the rotor 2 , a circuit board 45 , a molded resin portion 40 covering the stator 3 and the circuit board 45 , and

bearings

11 and 12 supporting the rotating shaft 10 . and A central axis Ax of the rotating shaft 10 defines the center of rotation of the rotor 2 . The stator 3 and the molded resin portion 40 constitute the molded stator 4 .

In the following, the direction of the central axis Ax will be referred to as the "axial direction". A radial direction centered on the central axis Ax is defined as a “radial direction”. A circumferential direction centered on the central axis Ax is defined as a “circumferential direction”.

The rotating shaft 10 protrudes from the molded stator 4 to one side in the axial direction. For example, an impeller 511 (FIG. 15A) of a blower is attached to the protruding portion of the rotating shaft 10 . Therefore, the side from which the rotating shaft 10 protrudes is called the "load side", and the opposite side is called the "counter-load side".

<Configuration of molded stator 4>
The molded stator 4 has the stator 3 and the molded resin portion 40 as described above. The mold resin portion 40 is made of thermosetting resin such as unsaturated polyester resin or epoxy resin. Unsaturated polyester resins are, for example, bulk molding compounds (BMC).

The molded resin portion 40 is an outer shell member and covers the radially outer side and anti-load side of the stator 3 . The mold resin portion 40 has an opening 41 on the load side and a bottom portion 42 on the anti-load side. The rotor 2 is inserted inside the stator 3 through the opening 41 . The molded resin portion 40 may have an opening 41 on the side opposite to the load and a bottom portion 42 on the load side, which will be described later with reference to FIG.

A metal bracket 13 that supports the bearing 11 on the load side is attached to the opening 41 of the mold resin portion 40 . The bracket 13 is an annular member centered on the central axis Ax, and holds the bearing 11 at its radially central portion.

A bottom portion 42 of the mold resin portion 40 is formed so as to cover the anti-load side of the stator 3 . A recess 43 is formed in the bottom 42 to accommodate the bearing 12 .

The bearing 11 has an inner ring 11a fixed to the rotating shaft 10, an outer ring 11b held by the bracket 13, and a plurality of rolling elements 11c provided between the inner ring 11a and the outer ring 11b. The rolling bodies 11c are, for example, balls. Bearing 11 is also referred to as the first bearing.

The bearing 12 has an inner ring 12a fixed to the rotating shaft 10, an outer ring 12b held in the recess 43 of the mold resin portion 40, and a plurality of rolling elements 12c provided between the inner ring 12a and the outer ring 12b. The rolling bodies 12c are, for example, balls. Bearing 12 is also referred to as a second bearing.

A circuit board 45 is arranged on the anti-load side of the stator 3 . The circuit board 45 has an annular shape, is disposed so as to radially surround the bearing 12 on the opposite side of the load, and is held by the mold resin portion 40 . Elements 45a such as a drive circuit are mounted on the circuit board 45, and lead wires 46 are wired. The lead wire 46 is drawn out from a drawing part 47 provided on the outer periphery of the mold resin portion 40 .

The outer shell member covering the stator 3 and the circuit board 45 is not limited to the mold resin portion 40, and may be, for example, a metal shell. The shell is, for example, a cylindrical member whose main component is Fe (iron), and the stator 3 is fixed inside the shell by shrink fitting or the like.

FIG. 2 is a cross-sectional view showing the rotor 2 and stator 3 of the electric motor 1. FIG. In FIG. 2, the mold resin portion 40 is omitted. The stator 3 has a stator core 30 and a coil 35 wound around the stator core 30 .

The stator core 30 is formed by laminating a plurality of magnetic thin plates in the axial direction and fixing them by caulking or the like. The magnetic thin plate is a thin plate containing Fe as a main component, more specifically an electromagnetic steel plate. The plate thickness of the magnetic thin plate is, for example, 0.2 mm to 0.5 mm. Instead of the laminate of magnetic thin plates, it is also possible to use a processed mass containing Fe as a main component.

The stator core 30 has an annular yoke 31 and a plurality of teeth 32 extending radially inward from the yoke 31 . Although the number of teeth 32 is 12 here, it is not limited to this. Tip portions of the teeth 32 are formed to face the rotor 2 .

A slot 33 is formed between the teeth 32 adjacent in the circumferential direction. The coil 35 is wound around the tooth 32 via the insulating portion 34 and accommodated in the slot 33 .

The insulating portion 34 is made of insulating resin such as PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), liquid crystal polymer (LCP), and PET (polyethylene terephthalate). Also, an insulating film with a thickness of 0.035 mm to 0.4 mm may be used.

The coils 35 are wound around the teeth 32 and housed in the slots 33 . The coil 35 is composed of magnet wire, for example. The winding method of the coil 35 may be either concentrated winding or distributed winding.

<Configuration of Rotor 2>
FIG. 3 is a cross-sectional view showing the rotor 2. As shown in FIG. As shown in FIG. 3 , the rotor 2 has a rotor core 20 fixed to the rotating shaft 10 and a plurality of permanent magnets 25 embedded in the rotor core 20 .

The rotor core 20 is a cylindrical member centered on the central axis Ax. The rotor core 20 is formed by stacking a plurality of thin magnetic plates in the axial direction and fixing them by caulking or the like. The magnetic thin plate is a thin plate containing Fe as a main component, more specifically an electromagnetic steel plate. The plate thickness of the magnetic thin plate is, for example, 0.2 mm to 0.5 mm.

The rotor core 20 has a shaft hole 23 in the center in the radial direction. The rotating shaft 10 is fixed in the shaft hole 23 . The fixing method is, for example, press fitting, shrink fitting, caulking, or integral molding with resin.

The rotor core 20 has a plurality of magnet insertion holes 21 in the circumferential direction. The magnet insertion holes 21 are arranged at equal intervals in the circumferential direction and at equal distances from the central axis Ax. A permanent magnet 25 is inserted into each magnet insertion hole 21 . The permanent magnet 25 has a flat plate shape and has a rectangular cross section in a plane perpendicular to the axial direction.

One permanent magnet 25 corresponds to one magnetic pole. Therefore, the rotor 2 has ten poles. However, the number of poles of the rotor 2 is not limited to ten, and may be two or more. The circumferential center of each magnetic pole is the pole center. A straight line in the radial direction passing through the pole center is called a magnetic pole centerline.

The permanent magnet 25 here is a rare earth magnet whose main component is Nd (neodymium) or Sm (samarium). Also, a ferrite magnet may be used instead of the rare earth magnet.

A hole 24 is formed radially inside the magnet insertion hole 21 of the rotor core 20 . The hole portion 24 is a through hole axially extending from one axial end of the rotor core 20 to the other axial end. It is desirable that the hole portion 24 is formed at a position corresponding to the center of the magnet insertion hole 21 in the circumferential direction, that is, on the pole center line.

Although the number of holes 24 is the same as the number of magnet insertion holes 21 here, it may be more or less than the number of magnet insertion holes 21 . Although the cross-sectional shape of the hole 24 is circular, it may have another shape (see FIG. 8 described later).

The shortest distance from the central axis Ax of the rotating shaft 10 to the hole 24 is called a distance Ls. A shortest distance from the central axis Ax to the magnet insertion hole 21 is called a distance Lm. The distance Ls and the distance Lm have a relationship of Ls<Lm.

FIG. 4 is a schematic diagram showing the rotor 2 and

bearings

11 and 12. FIG. The distance from the central axis Ax to the outer circumference of the bearing 11 (more specifically, the outer circumference of the outer ring 11b) is equal to the distance from the central axis Ax to the outer circumference of the bearing 12 (more specifically, the outer circumference of the outer ring 12b). Let this distance be distance Lb.

A distance Ls from the central axis Ax to the hole 24 and a distance Lb from the central axis Ax to the outer peripheries of the

bearings

11 and 12 have a relationship of Lb<Ls. In other words, the holes 24 are formed radially outside the outer peripheries of the

bearings

11 and 12 .

When the outer diameters of the

bearings

11 and 12 are different, that is, when the distance from the central axis Ax to the outer circumference of the bearing 11 and the distance from the central axis Ax to the outer circumference of the bearing 12 are different, the shorter of these It is sufficient if the distance Ls is shorter than the distance Lb on the other side.

As shown in FIG. 1, the axial length of the rotor 2 is longer than the axial length of the stator 3. As a result, the magnetic flux emitted from the rotor 2 flows into not only the tips of the teeth 32 but also the axial end faces of the stator core 30 .

In addition, the rotating shaft 10 has a large amount of protrusion from the rotor core 20 toward the load side, and a small amount of protrusion toward the anti-load side. Therefore, the end region of the rotating shaft 10 on the load side is called a long shaft portion, and the end region on the anti-load side is called a short shaft portion.

<Manufacturing Method of Electric Motor 1>
FIG. 5 is a flow chart showing manufacturing steps of the electric motor 1 according to the first embodiment. In the manufacturing process of the electric motor 1, first, the stator 3 is assembled. That is, the stator core 30 is formed by laminating a plurality of magnetic thin plates in the axial direction and fixing them by caulking or the like (step S101).

Next, the insulating portion 34 is attached to the stator core 30 or integrally molded, and the coil 35 is wound around the stator core 30 via the insulating portion 34 (step S102). This completes assembly of the stator 3 . Then, the circuit board 45 is mounted on the stator 3 and integrally molded with molding resin to obtain the molded stator 4 (step S103).

In parallel with these steps S101 to S103, the rotor 2 is assembled. That is, the rotor core 20 is formed by laminating a plurality of magnetic thin plates in the axial direction and fixing them by caulking or the like (step S104).

Next, the permanent magnet 25 is inserted into the magnet insertion hole 21 (step S105). Further, the rotary shaft 10 is fixed to the shaft hole 23 of the rotor core 20 by shrink fitting or press fitting (step S106). This completes assembly of the rotor 2 .

After that, the bearing 11 is attached to the load side of the rotary shaft 10, and the bearing 12 is attached to the anti-load side (step S107). As a result, the rotating shaft 10 of the rotor 2 and the

bearings

11 and 12 are integrated.

Next, the rotor 2 is inserted into the stator 3 (step S108). FIG. 6 is a schematic diagram showing a method of inserting the rotor 2 into the stator 3. As shown in FIG. As shown in FIG. 6, a jig 5 is used to insert the rotor 2 into the stator 3 . The jig 5 has a plurality of shafts 51 to be inserted into the holes 24 of the rotor 2 and a support plate 52 for supporting them.

The number of shaft portions 51 is the same as the number of hole portions 24, for example. In this case, the shaft portion 51 is inserted into all the holes 24 of the rotor 2 . However, the number of shaft portions 51 may be less than the number of hole portions 24 . For example, the number of shaft portions 51 may be half the number of holes 24 and the shaft portions 51 may be inserted into every other hole portion 24 . Further, the support plate 52 has a center hole 53 through which the rotating shaft 10 is inserted.

Here, the shaft portion 51 of the jig 5 is inserted into the hole portion 24 of the rotor 2 from the load side of the rotary shaft 10 through the radially outer side of the bearing 11 . The jig 5 may be inserted into the hole 24 of the rotor 2 from the non-load side of the rotary shaft 10, which will be described later (FIG. 7).

As described above, the distance Ls from the central axis Ax to the hole 24 is longer than the distance Lb from the central axis Ax to the outer circumference of the bearing 11 (see FIG. 4). does not interfere.

The rotor 2 is axially inserted inside the stator 3 through the opening 41 of the molded stator 4 while the jig 5 is used to hold the rotor 2 . Thereby, the rotor 2 is arranged radially inside the stator 3 .

When the rotor 2 is arranged radially inward of the stator 3 , the anti-load side bearing 12 fits into the recess 43 formed in the bottom 42 of the mold resin portion 40 .

After that, the jig 5 is pulled out from the stator 3 in the axial direction. Since the bearing 12 is fitted in the concave portion 43 of the molded resin portion 40 , the bearing 12 , the rotating shaft 10 fixed thereto, and the rotor core 20 and the bearing 11 fixed to the rotating shaft 10 are all connected to the molded stator 4 . left on the side and only the jig 5 is pulled out.

After that, the bracket 13 (FIG. 1) is fitted into the opening 41 of the molded stator 4, and the bearing 11 is attached to this bracket 13. Further, the cap 14 (FIG. 1) is attached to the rotating shaft 10 so as to cover the outside of the bracket 13 (step S109). Thus, the electric motor 1 is completed.

<Action>
Next, the operation of Embodiment 1 will be described. Generally, when inserting the rotor 2 inside the stator 3 , the rotor 2 is inserted inside the stator 3 while gripping the load-side end of the rotating shaft 10 .

On the other hand, the rotor 2 has a permanent magnet 25, and magnetic attraction acts between it and the stator 3. Therefore, the end of the rotor 2 on the opposite side of the load tends to sway and possibly come into contact with the stator 3 . When the rotor 2 and the stator 3 come into contact with each other, there is a possibility that these deformations will occur, or abrasion powder will be generated due to wear.

In the first embodiment, since the hole portion 24 of the rotor core 20 is formed radially outside the outer circumference of the bearing 11 (Ls>Lb), the shaft portion 51 of the jig 5 is positioned outside the bearing 11. It can be passed through and inserted into the hole 24 . Thereby, the rotor 2 can be inserted inside the stator 3 while being held by the jig 5 .

Therefore, even if a magnetic attraction force acts between the rotor 2 and the stator 3, the rotor 2 can be inserted without contacting the stator 3. Therefore, deformation due to contact between the rotor 2 and the stator 3 and generation of abrasion powder can be suppressed.

In addition, since the holes 24 are formed radially inward of the permanent magnets 25 (Lm>Ls), the holes 24 can prevent the flow of magnetic flux in the rotor core 20 from being hindered as much as possible.

Further, since a plurality of holes 24 are formed in the rotor core 20 at regular intervals in the circumferential direction, a plurality of shafts 51 provided on the jig 5 can be inserted into the holes 24 . Therefore, the rotor 2 can be held in a stable state, and contact between the rotor 2 and the stator 3 can be effectively suppressed.

In particular, since the cross-sectional shape of the hole portion 24 is circular, the shaft portion 51 of the jig 5 also has a cylindrical shape. Therefore, it is easy to manufacture the jig 5, and it is easy to improve the dimensional accuracy. Moreover, the outer diameter of the shaft portion 51 can be increased to reduce the gap between the shaft portion 51 and the hole portion 24, and the strength of the jig 5 can be improved. As a result, contact between the rotor 2 and the stator 3 can be suppressed more effectively.

Also, since the hole 24 is formed on the pole center line, the magnetic flux emitted from the inner peripheral surface of the permanent magnet 25 can be evenly guided to both sides in the circumferential direction. As a result, the unevenness of the magnetic flux in the rotor core 20 can be reduced, and the torque fluctuation of the electric motor 1 can be suppressed.

Although an example in which the hole 24 is formed on the pole center line has been described here, the present invention is not limited to this example, and the hole 24 is formed at a position that does not hinder the flow of magnetic flux in the rotor core 20 as much as possible. All you have to do is

<Effect of Embodiment>
As described above, the rotor 2 of Embodiment 1 has the rotating shaft 10, the rotor core 20 attached to the rotating shaft 10, and the permanent magnets 25 fixed to the rotor core 20. The rotor core 20 is axially It has an extending bore 24 . The distance Lm from the central axis Ax of the rotary shaft 10 to the permanent magnet 25, the distance Ls from the central axis Ax to the hole 24, and the distance Lb from the central axis Ax to the outer peripheries of the

bearings

11 and 12 satisfy Lm>Ls. >Lb is satisfied.

Therefore, the shaft portion 51 of the jig 5 can be passed through the outside of the bearing 11 and inserted into the hole portion 24 , and can be inserted inside the stator 3 while the rotor 2 is held by the jig 5 . Thereby, the rotor 2 can be inserted without contacting the stator 3, and deformation or wear of the rotor 2 and the stator 3 can be suppressed.

In addition, since the holes 24 are formed radially inward of the permanent magnets 25, the flow of magnetic flux in the rotor core 20 can be prevented from being hindered by the holes 24 as much as possible.

Modification 1.
FIG. 7 is a diagram showing a method of inserting the rotor 2 inside the stator 3 in Modification 1. As shown in FIG. In Modification 1, the load side and the anti-load side (that is, the long axis portion and the short axis portion) of the rotating shaft 10 are reversed from those in the first embodiment.

In the above-described first embodiment, as shown in FIGS. 1 and 6, the load side of rotating shaft 10, that is, the long shaft portion, protrudes from opening 41 of molded resin portion 40, and the anti-load side, that is, the short shaft portion of rotating shaft 10 protrudes from opening portion 41. The shaft portion was covered with the bottom portion 42 of the mold resin portion 40 .

On the other hand, in Modified Example 1, as shown in FIG. 7, the load side (right side in FIG. 7) of the rotary shaft 10, that is, the long shaft portion protrudes from a through hole 44 formed in the bottom portion 42 of the mold resin portion 40, The anti-load side (left side in FIG. 7) of the rotary shaft 10 , that is, the short shaft portion protrudes from the opening 41 of the mold resin portion 40 .

When inserting the rotor 2 into the stator 3 , the end of the rotating shaft 10 on the load side passes through the through hole 44 of the mold resin portion 40 and is held by the gripping jig 6 . Also, the anti-load side of the rotating shaft 10 is held by a jig 5 .

The configuration of the jig 5 is as described in Embodiment 1, but the support plate 52 of the jig 5 does not need to be provided with the center hole 53 through which the rotating shaft 10 passes.

In this modified example 1, the rotor 2 can be inserted inside the stator 3 while both ends of the rotating shaft 10 on the load side and the anti-load side are held. Thereby, the contact between the rotor 2 and the stator 3 can be suppressed more effectively.

Modification 2.
FIG. 8 is a cross-sectional view showing a rotor 2A of Modification 2. As shown in FIG. The rotor 2A of Modification 2 differs from the hole 24 of the rotor 2 of the first embodiment in the shape of the hole 26 . A rotor 2A of Modification 2 is configured in the same manner as the rotor 2 of Embodiment 1 except for the shape of hole portions 26 .

The hole portion 26 has a first edge 26a facing the rotary shaft 10 and a second edge 26b on the opposite side in a plane orthogonal to the axial direction. The first edge 26a extends linearly. The second edge 26b is curved so as to be convex in a direction away from the rotary shaft 10. As shown in FIG.

The hole portion 26 has two radially extending side edges 26c between the first edge 26a and the second edge 26b. However, the hole 26 does not necessarily have the side edge 26c. In other words, the hole 26 may be formed in a semicircular shape by the first edge 26a and the second edge 26b.

Since more magnetic flux flows in the rotor core 20 toward the outer circumference, it is desirable to form the hole 26 as close to the inner circumference of the rotor core 20 as possible in order to prevent the magnetic flux from being blocked as much as possible. On the other hand, in order to improve the strength of the jig 5 (FIG. 6), it is desirable that the cross-sectional area of the hole 26 into which the shaft 51 is inserted is large.

In Modification 2, since the first edge 26a of the hole 26 is linear and the second edge 26b is curved, the distance Ls from the central axis Ax to the hole 26 is the same as in the first embodiment. , the cross-sectional area of the hole portion 26 can be increased. As a result, the strength of the jig 5 can be improved while preventing the magnetic flux in the rotor core 20 from being interrupted as much as possible.

Embodiment 2.
Next, Embodiment 2 will be described. FIG. 9 is a longitudinal sectional view showing a rotor 2B of Embodiment 2. FIG. The rotor core 20 of the rotor 2B of Embodiment 2 has a first core portion 201 and a second core portion 202 in the axial direction. The first core portion 201 and the second core portion 202 have different cross-sectional areas of the holes.

The rotor core 20 has a first core portion 201 at one end in the axial direction, and a second core portion 202 from the central portion to the other end in the axial direction. Here, the rotor core 20 has a first core portion 201 at the end on the load side.

FIG. 10 is a cross-sectional view of the rotor 2B taken along line XX shown in FIG. As shown in FIG. 10 , a hole portion 27 as a first hole portion is formed radially inside the magnet insertion hole 21 of the first core portion 201 .

The distance Lm from the central axis Ax to the magnet insertion hole 21, the distance Ls from the central axis Ax to the hole 27, and the distance Lb (FIG. 9) from the central axis Ax to the

bearings

11 and 12 satisfy Lm>Ls> satisfy Lb. The diameter of the hole 27 is A1.

FIG. 11 is a cross-sectional view of the rotor 2B taken along line XI-XI shown in FIG. As shown in FIG. 11 , a hole portion 28 as a second hole portion is formed inside the magnet insertion hole 21 of the second core portion 202 in the radial direction.

The distance Lm from the central axis Ax to the magnet insertion hole 21, the distance Ls' from the central axis Ax to the hole 28, and the distance Lb (FIG. 9) from the central axis Ax to the

bearings

11 and 12 satisfy Lm>Ls. '>Lb is satisfied. The diameter of the hole 28 is A2.

The center of the hole 27 (Fig. 10) and the center of the hole 28 (Fig. 11) match. In other words, the

holes

27 and 28 are coaxial. Moreover, the inner diameter A1 of the hole portion 27 is larger than the inner diameter A2 of the hole portion 28 . In other words, the cross-sectional area of the hole 27 in the plane orthogonal to the axial direction is larger than the cross-sectional area of the hole 28 .

12A and 12B are diagrams showing a method of inserting the rotor 2B into the stator 3. FIG. A shaft portion 51 of the jig 5B has a root portion 51a inserted into the hole portion 27 of the rotor 2B and a tip portion 51b inserted into the hole portion 28. As shown in FIG. The root portion 51a and the tip portion 51b are coaxially formed.

It is desirable that the hole formed in the rotor core 20 have a small cross-sectional area so as not to interfere with the magnetic flux in the rotor core 20 as much as possible. On the other hand, if the cross-sectional area of the hole is reduced, the shaft portion 51 to be inserted into the hole must be made thin, which reduces the strength of the jig 5B.

In the rotor 2B of the second embodiment, since the inner diameter A2 of the hole 28 of the second core portion 202 is small, the flow of magnetic flux can be prevented as much as possible. Moreover, since the inner diameter A1 of the hole portion 27 of the first core portion 201 is large, the root portion 51a of the shaft portion 51 can be thickened and the strength of the shaft portion 51 can be increased.

Here, the rotor core 20 has a first core portion 201 at one axial end and a second core portion 202 at the other portion. However, the ratio of the axial lengths of the first core portion 201 and the second core portion 202 can be changed as appropriate. For example, the axial length of the first core portion 201 and the axial length of the second core portion 202 may be the same.

Alternatively, the second core portion 202 may be provided in the center of the rotor core 20 in the axial direction, and the first core portions 201 may be provided at both ends in the axial direction.

Except for the points described above, the rotor 2B of the second embodiment is configured similarly to the rotor 2 of the first embodiment. It should be noted that the load side and the anti-load side may be reversed when the rotor 2B is inserted into the stator 3, as in Modification 1 shown in FIG. Moreover, the shape of the

holes

27 and 28 of the rotor 2B may be the same shape as the hole 26 of the comparative example 2 shown in FIG.

As described above, in Embodiment 2, the rotor core 20 has the first core portion 201 and the second core portion 202 in the axial direction, and the first core portion 201 extends at least in the axial direction of the rotor core 20 . Positioned at one end, the cross-sectional area of the hole 27 of the first core portion 201 is larger than the cross-sectional area of the hole 28 of the second core portion 202 . Therefore, the magnetic path of the rotor core 20 is prevented from being blocked as much as possible to stabilize the output, and the strength of the jig 5B is ensured to enhance the effect of suppressing the contact between the rotor 2B and the stator 3.

Embodiment 3.
Next, Embodiment 3 will be described. FIG. 13 is a cross-sectional view showing rotor 2C of the third embodiment. The rotor 2C of Embodiment 3 is a consequent-pole rotor in which magnet magnetic poles P1 and virtual magnetic poles P2 are alternately arranged in the circumferential direction.

The rotor 2C has a plurality of magnet insertion holes 21 along the outer circumference of the rotor core 20 . The number of magnet insertion holes 21 is half the number of magnet insertion holes 21 (FIG. 2) in the first embodiment. The magnet insertion holes 21 are arranged at regular intervals in the circumferential direction. Flux barriers 22 are formed at both ends of each magnet insertion hole 21 in the circumferential direction to suppress leakage magnetic flux.

A permanent magnet 25 is arranged in each magnet insertion hole 21 . The permanent magnets 25 are arranged with the same magnetic pole faces (for example, N poles) directed toward the outer circumference. A portion of the rotor core 20 located between the adjacent permanent magnets 25 has a portion through which the magnetic flux flows in the radial direction.

Therefore, in the consequent-pole rotor 2C, the magnet magnetic pole P1 as the first magnetic pole formed by the permanent magnet 25 and the virtual magnetic pole P2 as the second magnetic pole formed by a part of the rotor core 20 are They are arranged alternately in the circumferential direction. In FIG. 13, the magnet magnetic pole P1 is the N pole and the virtual magnetic pole P2 is the S pole, but the magnet magnetic pole P1 may be the S pole and the virtual magnetic pole P2 may be the N pole.

The consequent-pole rotor 2C has half the number of permanent magnets 25 compared to the non-consequent-pole rotor 2 (FIG. 3) having the same number of poles, and can significantly reduce manufacturing costs.

In the rotor 2C of Embodiment 3, holes 24 are formed in the virtual magnetic poles P2 of the rotor core 20 . The distance Lm from the central axis Ax to the magnet insertion hole 21, the distance Ls from the central axis Ax to the hole 24, and the distance Lb from the central axis Ax to the outer peripheries of the

bearings

11 and 12 satisfy Lm>Ls>Lb. Be satisfied.

Since the virtual magnetic pole P2 is not provided with a permanent magnet, the hole 24 can be brought closer to the outer circumference of the rotor core 20. Therefore, the hole portion 24 can be enlarged while satisfying the above inequality. As a result, the shaft portion 51 (FIG. 6) inserted into the hole portion 24 can be made thicker to increase the strength, and the effect of suppressing the contact between the rotor 2C and the stator 3 can be enhanced.

Also, in the consequent-pole rotor 2C, the virtual magnetic pole P2 does not have a magnet insertion hole, so the core amount of the virtual magnetic pole P2 is larger than the core amount of the magnet magnetic pole P1. Note that the amount of core is the amount of core material such as a magnetic thin plate.

Since the core amount of the virtual magnetic pole P2 is larger than that of the magnet magnetic pole P1, the magnetic attraction force between the rotor 2C and the stator 3 is greater at the virtual magnetic pole P2 than at the magnetic magnetic pole P1. As a result, vibration and noise may occur due to differences in magnetic attraction.

By forming the hole 24 in the virtual magnetic pole P2, the core amount of the magnet magnetic pole P1 and the core amount of the virtual magnetic pole P2 can be brought close to each other. As a result, vibration and noise caused by the difference in magnetic attraction force between the magnet magnetic pole P1 and the virtual magnetic pole P2 can be reduced.

Here, the arrangement of the holes 24 will be further described. FIG. 14 is a diagram for explaining the arrangement of the holes 24 in the rotor 2C. On the side of the virtual magnetic pole P2 of the flux barrier 22, which is a part of the magnet insertion hole 21, an edge E that defines the position of the circumferential end of the virtual magnetic pole P2 is formed.

In the outer circumference 20a of the rotor core 20, the circumferential length of the portion corresponding to between two adjacent edges E is defined as Lv. This Lv corresponds to the circumferential width of the virtual magnetic pole P2 on the outer circumference 20 a of the rotor core 20 .

When the magnet magnetic pole P1 is the N pole, the magnetic flux emitted from the outer peripheral surface of the permanent magnet 25 flows through the stator core 30, flows into the virtual magnetic pole P2, and returns to the inner peripheral surface of the permanent magnet 25. The circumferential width Lv of the virtual magnetic poles P2 on the outer circumference 20a of the rotor core 20 is desirably wide enough so that magnetic flux from the permanent magnets 25 can be received.

Also, in order to improve the strength of the jig 5, it is desirable that the inner diameter of the hole 24 into which the shaft 51 is inserted is large. If the inner diameter is increased without changing the radial position of the center of the hole 24, the region R from the hole 24 to the outer circumference 20a of the rotor core 20 becomes narrower. However, since the magnetic flux flowing from the magnet magnetic pole P1 to the virtual magnetic pole P2 can flow radially on both circumferential sides of the hole 24, the area R can be narrowed. Therefore, the distance La from the hole 24 to the outer circumference 20a of the rotor core 20 (that is, the radial width of the region R) can be shortened so as to satisfy La<Lv.

However, since it is difficult to make the distance La from the hole 24 to the outer circumference 20a of the rotor core 20 narrower than the plate thickness of the magnetic thin plate of the rotor core 20, the distance La is set to be equal to or greater than the plate thickness of the magnetic thin plate. .

The hole 24 is preferably formed at a position where the magnetic flux density in the area B between the magnet insertion hole 21 and the hole 24 is 1.6 T or more. In this case, since the region B is magnetically saturated, the region B does not exhibit the original magnetic properties of the core material with respect to the magnetic flux flowing from the stator 3 . In other words, with respect to the magnetic flux flowing from the stator 3, the region B is in the same state as if the core material were not present. As a result, the core amount of the magnet magnetic pole P1 and the core amount of the virtual magnetic pole P2 can be brought closer to each other, and vibration and noise can be further reduced.

Except for the points described above, the rotor 2C of the third embodiment is configured in the same manner as the rotor 2 of the first embodiment. It should be noted that the load side and the anti-load side may be reversed when the rotor 2C is inserted into the stator 3, as in Modification 1 shown in FIG. Further, the shape of the hole portion 24 of the rotor 2C may be the same shape as the hole portion 26 of the comparative example 2 shown in FIG. Further, the rotor core 20 of the rotor 2C may be formed of a plurality of core portions having holes with different cross-sectional areas as in the second embodiment.

As described above, in the third embodiment, the consequent-pole rotor 2C has the holes 24 in the virtual magnetic poles P2. Therefore, in addition to the effects described in the first embodiment, the core amount of the magnet magnetic pole P1 and the core amount of the virtual magnetic pole P2 are brought closer to reduce vibration and noise caused by the difference in magnetic attraction force with the stator 3. can be done.

<Air conditioner>
Next, an air conditioner to which the electric motor 1 of each embodiment and each modification described above can be applied will be described. FIG. 15(A) is a diagram showing the configuration of an air conditioner 500 to which the electric motor 1 of Embodiment 1 is applied. An air conditioner 500 includes an outdoor unit 501 and an indoor unit 502 . The outdoor unit 501 and the indoor unit 502 are connected by a refrigerant pipe 503 .

The outdoor unit 501 includes a compressor 504, a condenser 505, and an outdoor fan 510. Outdoor fan 510 is, for example, a propeller fan. The outdoor fan 510 has an impeller 511 and an electric motor 1A for driving the same.

The indoor unit 502 includes an evaporator 506 and an indoor fan 520. Indoor fan 520 is, for example, a cross-flow fan. The indoor fan 520 has an impeller 521 and an electric motor 1B for driving the same.

15(B) is a cross-sectional view of the outdoor unit 501. FIG. The electric motor 1A is supported by a frame 509 arranged inside a housing 508 of the outdoor unit 501. As shown in FIG. An impeller 511 is attached to the rotary shaft 10 of the electric motor 1 via a hub 512 .

In the outdoor blower 510, the impeller 511 is rotated by the electric motor 1A to blow air outdoors. During the cooling operation of the air conditioner 500 , the heat released when the refrigerant compressed by the compressor 504 is condensed by the condenser 505 is released to the outside by the air blown by the outdoor fan 510 .

In the indoor blower 520 (FIG. 15(A)), the impeller 521 is rotated by the electric motor 1B to blow air into the room. During the cooling operation of the air conditioner 500 , the indoor fan 520 blows the air from which heat was removed when the refrigerant was evaporated in the evaporator 506 into the room.

Since the

electric motors

1A and 1B are configured with the electric motor 1 of Embodiment 1, they can be stably operated over a long period of time by preventing contact between the rotor 2 and the stator 3. Therefore, the reliability of outdoor fan 510 and indoor fan 520 can be improved.

The

electric motors

1A and 1B are not limited to the electric motor 1 of the first embodiment, and may be the electric motors of the second and third embodiments or the modifications. Also, although the electric motors of the embodiments and modifications are used for both the outdoor fan 510 and the indoor fan 520 here, they may be used for only one of them.

Although the preferred embodiments have been specifically described above, the present disclosure is not limited to the above embodiments, and various improvements and modifications can be made.

1, 1A, 1B electric motor, 2, 2A, 2B, 2C rotor, 3 stator, 4 molded stator, 5, 5B jig, 10 rotating shaft, 11 bearing (first bearing), 12 bearing (second bearing) , 13 bracket, 20 rotor core, 21 magnet insertion hole, 23 shaft hole, 24 hole, 25 permanent magnet, 26 hole, 26a first edge, 26b second edge, 26c side edge, 27, 28 hole 30 Stator core 31 Yoke 32 Teeth 33 Slot 35 Coil 40 Mold resin part 41 Opening 42 Bottom 43 Recess 44 Through hole 45 Circuit board 50 Jig 51 Shaft 51a Root , 51b tip, 52 support plate, 201 first core, 202 second core, 500 air conditioner, 501 outdoor unit, 502 indoor unit, 510 outdoor blower (blower), 511 impeller, 520 indoor blower (Blower, 521 impeller.

Claims

a rotating shaft on which the bearings are mounted;
a rotor core fixed to the rotating shaft;
permanent magnets fixed to the rotor core;
The rotor core has a hole extending in the axial direction of the rotating shaft,
The distance Lm from the central axis of the rotating shaft to the permanent magnet, the distance Ls from the central axis to the hole, and the distance Lb from the central axis to the outer periphery of the bearing satisfy Lm>Ls>Lb. Satisfied rotor.
The permanent magnet constitutes a magnetic pole,
The rotor according to claim 1, wherein the hole is formed in a straight line passing through the center of the magnetic pole and the central axis.
A rotor according to claim 1 or 2, wherein the hole has a circular cross-section.
In a plane orthogonal to the axial direction, the hole has a first edge facing the rotating shaft and a second edge opposite to the rotating shaft,
4. The rotor according to any one of claims 1 to 3, wherein said first edge is straight and said second edge is curved so as to be convex in a direction away from said rotating shaft.
The rotor core has a first core portion and a second core portion in the axial direction,
The first core portion is positioned at least one end of the rotor core in the axial direction,
The rotor according to any one of claims 1 to 4, wherein the cross-sectional area of the hole in the first core portion is larger than the cross-sectional area of the hole in the second core portion.
the permanent magnet constitutes a first magnetic pole, a part of the rotor core constitutes a second magnetic pole,
The rotor according to any one of claims 1 to 5, wherein the hole is formed in the second magnetic pole of the rotor core.
The rotor core has magnet insertion holes into which the permanent magnets are inserted,
7. The rotor according to claim 6, wherein the holes are arranged such that a magnetic flux density in a region between the holes and the magnet insertion holes is 1.6 T or more.
The rotor core has two magnet insertion holes into which the permanent magnets are inserted respectively, and the second magnetic pole is formed between the two magnet insertion holes,
The length Lv of the outer circumference of the rotor core corresponding to the space between the two magnet insertion holes and the distance La from the hole to the outer circumference of the rotor core satisfy La<Lv according to claim 6 or 7. rotor.
a rotor according to any one of claims 1 to 8;
an annular stator surrounding the rotor;
and the bearing fixed to the stator and rotatably supporting the rotating shaft.
The electric motor according to claim 9;
and an impeller attached to the rotating shaft of the electric motor.
Equipped with an outdoor unit and an indoor unit,
At least one of the outdoor unit and the indoor unit has the fan according to claim 10. An air conditioner.
assembling a rotor having a rotating shaft, a rotor core fixed to the rotating shaft and having a hole in the axial direction of the rotating shaft, and a permanent magnet attached to the rotor core;
assembling an annular stator;
attaching a bearing to the rotating shaft of the rotor;
A method of manufacturing an electric motor, comprising: inserting the rotor into the stator while inserting the shaft of a jig into the hole to hold the rotor.
The rotating shaft has a long shaft portion and a short shaft portion that project from the rotor core in different amounts in the axial direction,
13. The method of manufacturing an electric motor according to claim 12, wherein the jig is inserted into the hole of the rotor from the long shaft portion side of the rotating shaft.
The rotating shaft has a long shaft portion and a short shaft portion that project from the rotor core in different amounts in the axial direction,
13. The method of manufacturing an electric motor according to claim 12, wherein the jig is inserted into the hole of the rotor from the short shaft portion side of the rotating shaft.