WO2024009450A1

WO2024009450A1 - Rotor, electric motor, blower, air conditioner, and manufacturing method for rotor

Info

Publication number: WO2024009450A1
Application number: PCT/JP2022/026944
Authority: WO
Inventors: 貴也下川; 隆徳渡邉; 洋樹麻生
Original assignee: 三菱電機株式会社
Priority date: 2022-07-07
Filing date: 2022-07-07
Publication date: 2024-01-11

Abstract

This rotor has: a shaft; a rotor core that surrounds the shaft from the outside in the radial direction thereof and has a magnet insertion hole; and a resin portion that includes a first resin portion positioned between the shaft and the rotor core and holds the shaft and the rotor core. The rotor core has a first end surface and a second end surface in the axial direction of the shaft. The magnet insertion hole extends from the first end surface to the second end surface. At least either in the first end surface or in the second end surface, the magnet insertion hole is not covered with the resin portion.

Description

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

The present disclosure relates to a rotor, an electric motor, a blower, an air conditioner, and a method for manufacturing a rotor.

A rotor of an electric motor includes a shaft, a rotor core attached to the shaft, a permanent magnet attached to the rotor core, and a resin part that holds the shaft and the rotor core (see, for example, Patent Document 1).

When manufacturing the rotor, a magnetic material is inserted into the magnet insertion hole of the rotor core, and the rotor core and shaft are integrally molded with resin. After that, the magnetic material is magnetized to form a permanent magnet.

International Publication WO2021/117176 (see abstract)

However, in conventional rotors, since the magnetic bodies are magnetized while being incorporated into the rotor, it is difficult to uniformly and sufficiently magnetize the magnetic bodies, and there is a problem that it is difficult to improve the magnetization rate of the permanent magnets.

The present disclosure has been made to solve the above problems, and aims to improve the magnetization rate of permanent magnets.

The rotor of the present disclosure includes a shaft, a rotor core that surrounds the shaft from the outside in the radial direction and has a magnet insertion hole, and a first resin part located between the shaft and the rotor core, and holds the shaft and the rotor core. It has a resin part. The rotor core has a first end surface and a second end surface in the axial direction of the shaft. The magnet insertion hole extends from the first end surface to the second end surface. The magnet insertion hole is not covered with the resin part in at least one of the first end face and the second end face.

A method for manufacturing a rotor according to the present disclosure includes a step of magnetizing a magnetic material to form a permanent magnet, a step of integrally molding a rotor core and a shaft having a magnet insertion hole with resin, and a step of molding a permanent magnet into a magnet insertion hole of the rotor core. and a step of inserting. In the step of integrally molding the rotor core and the shaft with resin, a magnet insertion hole is exposed in at least one of the first end surface and the second end surface of the rotor core in the axial direction of the shaft.

According to the present disclosure, since the magnet insertion hole of the rotor core is not covered with the resin part, a singly magnetized permanent magnet can be inserted into the magnet insertion hole of the rotor core that is integrally molded with the shaft. Therefore, the magnetization rate of the permanent magnet can be improved.

1 is a longitudinal sectional view showing the electric motor of Embodiment 1. FIG. 1 is a cross-sectional view showing the electric motor of Embodiment 1. FIG. 1 is a cross-sectional view showing a rotor of Embodiment 1. FIG. 1 is a longitudinal sectional view showing a rotor of Embodiment 1. FIG. FIG. 2 is a diagram (A) of the rotor of Embodiment 1 viewed from the load side and a diagram (B) of the rotor viewed from the anti-load side. FIGS. 3A and 3B are diagrams illustrating an example of a method for fixing a nonmagnetic material according to Embodiment 1. FIGS. 3 is a flowchart showing the manufacturing process of the rotor of Embodiment 1. FIG. FIG. 3 is a longitudinal cross-sectional view showing a mold used in the manufacturing process of the rotor of Embodiment 1. FIG. 3 is a diagram for explaining a permanent magnet insertion process according to the first embodiment. It is a longitudinal cross-sectional view which shows the rotor of a modification. FIG. 3 is a cross-sectional view showing a rotor according to a second embodiment. FIG. 3 is a diagram of the rotor of Embodiment 2 viewed from the anti-load side. FIG. 3 is a vertical cross-sectional view showing a rotor according to a second embodiment. 7A and 7B are diagrams illustrating an example of a method for fixing a rotor according to a second embodiment; FIG. 7 is a diagram illustrating another example of the method of fixing a nonmagnetic material according to the second embodiment. FIG. They are a diagram (A) showing an air conditioner to which the electric motor of each embodiment and modification can be applied, and a diagram (B) showing an outdoor unit thereof.

Embodiment 1.
<Overall configuration of electric motor 1>
The electric motor of Embodiment 1 will be explained. FIG. 1 is a longitudinal cross-sectional view showing an electric motor 1 according to the first embodiment. The electric motor 1 is a synchronous motor, and is used, for example, in a blower of an air conditioner 500 (FIG. 16(A)).

The electric motor 1 includes a rotor 2 having a shaft 10, a stator 5 surrounding the rotor 2, a circuit board 70, a molded resin part 60 covering the stator 5 and the circuit board 70, and

bearings

11 and 12 supporting the shaft 10. Be prepared. The central axis Ax of the shaft 10 defines the rotation center of the rotor 2. Stator 5 and molded resin portion 60 constitute molded stator 6 .

Hereinafter, the direction of the central axis Ax will be referred to as the "axial direction." The radial direction centered on the central axis Ax is defined as the "radial direction." The circumferential direction centered on the central axis Ax is defined as the "circumferential direction." Further, a cross-sectional view taken in a plane perpendicular to the central axis Ax is referred to as a "transverse cross-sectional view", and a cross-sectional view taken in a plane parallel to the central axis Ax is referred to as a "longitudinal cross-sectional view".

The shaft 10 protrudes from the molded stator 6 to one side in the axial direction. For example, an impeller 511 (FIG. 16(A)) of a blower is attached to the protrusion of the shaft 10. Therefore, the side from which the shaft 10 protrudes is called the "load side", and the opposite side is called the "counter-load side".

<Configuration of mold stator 6>
As described above, the molded stator 6 includes the stator 5 and the molded resin part 60. The mold resin part 60 is made of a thermosetting resin such as unsaturated polyester resin or epoxy resin. The unsaturated polyester resin is, for example, bulk molding compound (BMC).

The molded resin part 60 is an outer shell member and covers the radially outer side and the anti-load side of the stator 5. The molded resin part 60 has an opening 61 on the load side and a bottom 62 on the anti-load side. The rotor 2 is inserted into the stator 5 through the opening 61.

A metal bracket 13 that supports the bearing 11 on the load side is attached to the opening 61 of the molded resin part 60. The bracket 13 is an annular member centered on the central axis Ax, and holds the bearing 11 at its radially central portion.

The bottom portion 62 of the molded resin portion 60 is formed to cover the anti-load side of the stator 5. A recess 63 is formed in the bottom 62 to accommodate the bearing 12.

A circuit board 70 is arranged on the anti-load side of the stator 5. The circuit board 70 has an annular shape and is held by the molded resin part 60. Elements 71 such as drive circuits are mounted on the circuit board 70, and lead wires 72 are wired. The lead wire 72 is drawn out from a drawing part 73 provided on the outer periphery of the molded resin part 60.

Note that the outer shell member that covers the stator 5 and the circuit board 70 is not limited to the molded resin part 60, 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 5 is fixed inside thereof by shrink fitting or the like.

FIG. 2 is a cross-sectional view showing the rotor 2 and stator 5 of the electric motor 1. In FIG. 2, the mold resin part 60 is omitted. Stator 5 includes a stator core 50 and a coil 55 wound around stator core 50.

The stator core 50 has a laminated body in which a plurality of magnetic laminated elements are laminated in the axial direction. The laminated element is a thin plate containing Fe as a main component, and more specifically, an electromagnetic steel plate. The thickness of the laminated element is, for example, 0.2 mm to 0.5 mm. Instead of a laminate of laminated elements, a processed lump containing Fe as a main component may be used.

The stator core 50 has an annular yoke 51 and a plurality of teeth 52 extending radially inward from the yoke 51. The number of teeth 52 is 12 here, but is not limited to this. A tip portion 52 a facing the rotor 2 is formed at the tip of the tooth 52 .

A slot 53 is formed between teeth 52 adjacent to each other in the circumferential direction. The coil 55 is wound around the teeth 52 via the insulating portion 54 and accommodated in the slot 53.

The insulating section 54 is made of an insulating resin such as PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), liquid crystal polymer (LCP), and PET (polyethylene terephthalate). Further, an insulating film may be provided to cover the inner surface of the slot 53.

The coil 55 is wound around the teeth 52 and accommodated in the slot 53. The coil 55 is made of, for example, a magnet wire. The coil 55 may be wound by 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 includes a rotor core 20 fixed to the shaft 10 and a plurality of permanent magnets 25 embedded in the rotor core 20.

The rotor core 20 is an annular member centered on the central axis Ax, and has an outer circumference 20c and an inner circumference 20d. The rotor core 20 has a laminated body in which a plurality of magnetic laminated elements are laminated in the axial direction. The laminated element is a thin plate containing Fe as a main component, and more specifically, an electromagnetic steel plate. The thickness of the laminated element is, for example, 0.2 mm to 0.5 mm.

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 number of poles of the rotor 2 is ten. However, the number of poles of the rotor 2 is not limited to ten, but may be two or more. The circumferential center of each magnetic pole is a pole center P. A straight line in the radial direction passing through the pole center P is referred to as a magnetic pole center line. A pole-to-pole portion M is defined between adjacent permanent magnets 25 .

The permanent magnet 25 here is a rare earth magnet containing Nd (neodymium), Fe (iron), and B (boron). Alternatively, a rare earth magnet containing Sm (samarium) and Co (cobalt) may be used. Further, a ferrite magnet may be used instead of a rare earth magnet.

A flux barrier 22, which is a gap, is formed at both circumferential ends of the magnet insertion hole 21. A thin portion is formed between the flux barrier 22 and the outer periphery 20c of the rotor core 20. In order to reduce leakage magnetic flux between adjacent magnetic poles, it is desirable that the thickness of the thin portion be the same as the thickness of the laminated element.

The outer periphery 20c of the rotor core 20 has a flower round shape. In other words, the outer circumference 20c of the rotor core 20 extends such that its outer diameter is maximum at the pole center P and minimum at the interpole portion M. However, the outer periphery 20c of the rotor core 20 is not limited to the round shape, but may have a circular shape, for example. The inner circumference 20d of the rotor core 20 has a circular shape.

The shaft 10 is made of metal such as mechanical structural carbon steel (S45C), for example.

A first resin portion 31 is provided between the shaft 10 and the inner circumference 20d of the rotor core 20. The first resin portion 31 is made of non-magnetic resin. More specifically, the first resin portion 31 is made of thermoplastic resin such as PBT, PPS, LCP, and PET.

FIG. 4 is a longitudinal cross-sectional view showing the rotor 2. The rotor core 20 has both end faces in the axial direction, that is, an end face 20a on the load side and an end face 20b on the anti-load side. The magnet insertion hole 21 extends in the axial direction from the end surface 20a to the end surface 20b. The end surface 20a is also referred to as a first end surface, and the end surface 20b is also referred to as a second end surface.

The shaft 10 protrudes from the rotor core 20 on both sides in the axial direction. A portion of the shaft 10 that protrudes from the end surface 20a of the rotor core 20 is referred to as a long shaft portion 10a. A portion of the shaft 10 that protrudes from the end surface 20b of the rotor core 20 is referred to as a short shaft portion 10b. The length of the long shaft portion 10a is longer than the length of the short shaft portion 10b.

Here, a case will be described in which the long shaft portion 10a of the shaft 10 is located on the load side and the short shaft portion 10b is located on the anti-load side. However, the long shaft portion 10a is located on the anti-load side and the short shaft portion 10b It may be located on the load side.

The first resin portion 31 is provided between the shaft 10 and the inner circumference 20d of the rotor core 20. More specifically, the first resin portion 31 is filled between the shaft 10 and the inner circumference 20d of the rotor core 20.

A second resin portion 32 is provided on the end surface 20a of the rotor core 20. The second resin part 32 is formed integrally with the first resin part 31.

Furthermore, a third resin portion 33 is provided on the end surface 20b of the rotor core 20. The third resin part 33 is formed integrally with the first resin part 31.

The first resin part 31, the second resin part 32, and the third resin part 33 constitute the resin part 30. The resin portion 30 has a function of holding the shaft 10 and the rotor core 20 together.

A non-magnetic material 34 is arranged on the end surface 20b of the rotor core 20 so as to cover at least a portion of the magnet insertion hole 21. The non-magnetic material 34 is located on the radially outer side of the third resin portion 33.

It is desirable that the non-magnetic material 34 is made of non-magnetic resin. The material of the non-magnetic body 34 may be the same as the material of the first resin part 31, or may be different. The non-magnetic material 34 is provided separately from the resin part 30. That is, the non-magnetic material 34 is arranged on the rotor core 20 in a step subsequent to the step in which the resin portion 30 is formed (described later).

FIG. 5(A) is a diagram of the rotor 2 viewed from the load side. As described above, the load-side end surface 20a of the rotor 2 is covered with the second resin portion 32. The second resin portion 32 has an annular shape centered on the central axis Ax, and has an outer periphery 32a and an inner periphery 32b. The shaft 10 is fixed to the inner circumference 32b of the second resin portion 32. The outer periphery 32 a of the second resin portion 32 is located radially outward from the radially inner end of the magnet insertion hole 21 . In other words, the second resin portion 32 covers at least a portion of the magnet insertion hole 21 .

FIG. 5(B) is a diagram of the rotor 2 viewed from the anti-load side. As described above, the end surface 20b of the rotor 2 on the opposite load side is covered with the third resin portion 33. The third resin portion 33 has an annular shape centered on the central axis Ax, and has an outer periphery 33a and an inner periphery 33b. The shaft 10 is fixed to the inner circumference 33b of the third resin portion 33. The outer periphery 33a of the third resin portion 33 is located radially inside the magnet insertion hole 21. In other words, the third resin part 33 does not cover the magnet insertion hole 21.

The non-magnetic material 34 is arranged radially outward from the third resin part 33. The non-magnetic body 34 has an annular shape centered on the central axis Ax, and has an outer periphery 34a and an inner periphery 34b. The inner periphery 34b of the non-magnetic material 34 is located on the outer side in the radial direction than the outer periphery 33a of the third resin portion 33. That is, the nonmagnetic material 34 is provided apart from the third resin part 33.

The outer periphery 34a of the non-magnetic material 34 is located radially outward from the radially inner end of the magnet insertion hole 21. That is, the nonmagnetic material 34 covers at least a portion of the magnet insertion hole 21 on the end surface 20b of the rotor core 20. The non-magnetic material 34 functions as a lid that prevents the permanent magnet 25 from falling out of the magnet insertion hole 21.

In the example shown in FIG. 5(B), the nonmagnetic material 34 covers the part of the magnet insertion hole 21 other than the flux barrier 22, but it may cover the entire magnet insertion hole 21 including the flux barrier 22. good.

Although the nonmagnetic material 34 is formed in an annular shape here, it may have another shape as long as it can cover at least a portion of the magnet insertion hole 21. Further, a plurality of non-magnetic bodies 34 may be provided so as to cover each magnet insertion hole 21.

FIG. 6(A) is a plan view showing an example of a method of fixing the non-magnetic material 34. In the example shown in FIG. 6(A), the nonmagnetic material 34 and the third resin part 33 are fixed by welding. Specifically, at least one rib 34c is provided on the inner periphery 34b of the non-magnetic material 34, and this rib 34c and the third resin part 33 are fixed by welding.

In FIG. 6(A), the number of ribs 34c is the same as the number of poles of the rotor 2, and the position of each rib 34c is made to coincide with the position of the pole center P. However, the number and arrangement of the ribs 34c are not limited to this example, and may be sufficient as long as the non-magnetic material 34 and the third resin part 33 can be fixed to each other.

FIG. 6(B) is a plan view showing another example of the method of fixing the non-magnetic material 34. In the example shown in FIG. 6(B), the non-magnetic material 34 is provided with an engaging portion 34d that engages with a part of the magnet insertion hole 21 (FIG. 5(B)) of the rotor core 20. Specifically, an engaging portion 34d that enters the flux barrier 22 of the magnet insertion hole 21 in the axial direction is provided on the outer periphery 34a of the non-magnetic material 34.

When the engaging portion 34d engages with the flux barrier 22, the non-magnetic material 34 is fixed to the rotor core 20. The engaging portion 34d has a shape that fits inside the flux barrier 22, and has an axial length sufficient to fix the non-magnetic material 34 to the rotor core 20.

In FIG. 6(B), the non-magnetic material 34 has the same number of engaging parts 34d as the flux barriers 22 of the rotor core 20, and the arrangement of each engaging part 34d matches the arrangement of the flux barriers 22. However, the present invention is not limited to such an example, and it is sufficient that at least one engaging portion 34d of the non-magnetic body 34 and the magnet insertion hole 21 engage with each other.

The non-magnetic material 34 may be fixed to the rotor core 20 or the third resin part 33 by other methods than the fixing method shown in FIGS. 6(A) and 6(B).

<Method for manufacturing rotor 2>
Next, a method for manufacturing the rotor 2 according to the first embodiment will be described. FIG. 7 is a flowchart showing a method for manufacturing the rotor 2 according to the first embodiment. In the manufacturing process of the rotor 2, first, a plurality of laminated elements are laminated in the axial direction and fixed by caulking or the like to form the rotor core 20 (step S11).

Next, the rotor core 20 and shaft 10 are placed in a mold and integrally molded with resin (step S12).

FIG. 8 is a cross-sectional view showing a mold 80 used in the molding process (step S12). The mold 80 has a fixed mold 81 and a movable mold 82. Here, the fixed mold 81 is the lower mold, and the movable mold 82 is the upper mold. The fixed mold 81 and the movable mold 82 have mold matching surfaces 81h and 82h that face each other.

The movable mold 82 can move toward and away from the fixed mold 81, here in the vertical direction. In the state shown in FIG. 8, the

mold mating surfaces

81h and 82h of the fixed mold 81 and the movable mold 82 are in contact with each other, and a cavity C, which is a molding space, is formed between the fixed mold 81 and the movable mold 82. It is formed.

The fixed mold 81 has a shaft hole 81a into which the long axis portion 10a of the shaft 10 is inserted, a cavity 81b into which the rotor core 20 is inserted, and a cavity 81c for forming the second resin part 32. .

It is desirable that the outer diameter of the cavity 81c is smaller than the outer diameter of the cavity 81b. In this case, the rotor core 20 can be supported from below by a portion of the fixed mold 81 outside the cavity 81b.

The movable mold 82 has a shaft hole 82a into which the short shaft portion 10b of the shaft 10 is inserted, and a cavity portion 82b for forming the third resin portion 33. The

cavities

81b and 81c of the fixed mold 81 and the cavity 82b of the movable mold 82 form one continuous cavity C.

Furthermore, the movable mold 82 is formed with a sprue 82c, which is a passage through which the molten resin injected from the injection molding machine flows, and a runner 82d, which is a passage for the molten resin from the sprue 82c to the cavity C.

Furthermore, the movable mold 82 has a pin 82e that enters the magnet insertion hole 21 of the rotor core 20 arranged in the cavity 81b of the fixed mold 81. The pin 82e is provided to prevent resin from entering the magnet insertion hole 21 during molding. The number of pins 82e is the same as the number of magnet insertion holes 21. Further, it is desirable that the pin 82e has the same cross-sectional shape as the magnet insertion hole 21.

Furthermore, the movable mold 82 has a contact surface 82f that comes into contact with the periphery of the magnet insertion hole 21 on the end surface 20b of the rotor core 20. The pin 82e and the contact surface 82f are for preventing resin from entering the magnet insertion hole 21.

In the molding process, first, the movable mold 82 is raised to open the cavity C. Next, the shaft 10 is inserted into the shaft hole 81a of the fixed mold 81, and the rotor core 20 is installed in the cavity 81b of the fixed mold 81.

Thereafter, the movable mold 82 is lowered to bring the mold matching surfaces 81h and 82h into contact. In this state, the end surface 20a of the rotor core 20 faces the cavity 81c of the fixed mold 81, and the end surface 20b of the rotor core 20 faces the cavity 82b.

Thereafter, the mold 80 is heated, and a molten resin such as PBT is injected from the sprue 82c and runner 82d. The resin fills the space inside the rotor core 20 within the cavity 81b. Further, the inside of the cavity 81c and the inside of the cavity 82b are also filled with the resin.

At this time, the contact surface 82f of the movable mold 82 is in contact with the end surface 20b of the rotor core 20, and the pin 82e of the movable mold 82 is engaged with the magnet insertion hole 21. Therefore, the resin does not flow into the magnet insertion hole 21.

After that, the mold 80 is cooled. As a result, the resin within the cavity C is cured, and the resin portion 30 is formed. More specifically, the first resin part 31 is formed inside the rotor core 20 in the cavity 81b, the second resin part 32 is formed in the cavity 81c, and the third resin part 32 is formed in the cavity 82b. 33 is formed. As a result, the shaft 10 and the rotor core 20 are held integrally by the resin portion 30.

Thereafter, the movable mold 82 is raised to open the cavity C, and the rotor core 20 integrally molded with the shaft 10 is taken out from the fixed mold 81.

In parallel with steps S11 and S12, the magnetic material is magnetized (step S13). The magnetic body is magnetized, for example, by a magnetizing device, and becomes a permanent magnet 25. Since the magnetic body is individually magnetized before being incorporated into the rotor 2, the magnetic body can be uniformly and sufficiently magnetized, and the magnetization rate of the permanent magnets 25 can be improved.

Thereafter, the magnetized permanent magnet 25 is attached to the rotor core 20 that is integrally formed with the shaft 10 (step S14).

FIG. 9 is a schematic diagram for explaining the process of inserting the permanent magnet 25 into the rotor core 20. As described above, the magnet insertion hole 21 is not covered with the resin portion 30 and is exposed on the end surface 20b of the rotor core 20. Furthermore, no resin enters the inside of the magnet insertion hole 21. Therefore, the permanent magnet 25 can be inserted into the magnet insertion hole 21 of the rotor core 20.

Furthermore, on the end surface 20a of the rotor core 20, at least a portion of the magnet insertion hole 21 is covered with a second resin portion 32. Therefore, the second resin portion 32 functions as an axial stopper for the permanent magnet 25 inserted into the magnet insertion hole 21.

After that, the non-magnetic material 34 is attached so as to cover at least a portion of the magnet insertion hole 21 of the rotor core 20 (step S15). The method of fixing the non-magnetic material 34 is as described with reference to FIGS. 6(A) and 6(B). This completes the rotor 2.

After the rotor 2 is completed, the electric motor 1 is assembled. That is, the stator core 50 is formed by laminating a plurality of laminated elements in the axial direction and fixing them by caulking or the like. Further, the stator 5 is obtained by attaching the insulating part 54 to the stator core 50 and winding the coil 55. The stator 5 and the circuit board 70 are placed in a mold for a molded stator, and a resin (mold resin) such as BMC is injected and heated to form the molded resin part 60. This completes the molded stator 6.

After that, the

bearings

11 and 12 are attached to the shaft 10 of the rotor 2, and these are inserted into the hollow part of the molded stator 6 through the opening 61. Next, the bracket 13 is attached to the opening 61 of the molded stator 6. Furthermore, a cap 14 is attached to the shaft 10 so as to cover the bracket 13. As a result, the electric motor 1 is completed.

<Effect>
In a typical manufacturing method for the rotor 2, first, a magnetic material is inserted into the magnet insertion hole 21 of the rotor core 20, and the shaft 10 and the rotor core 20 are integrally molded with resin. Thereafter, the shaft 10 and rotor core 20 are mounted on a magnetizing device, and the magnetic material is magnetized to form a permanent magnet 25. Such a magnetization method is called built-in magnetization.

However, when magnetizing the magnetic body while it is incorporated in the rotor 2, it is difficult to uniformly and sufficiently magnetize the entire magnetic body, and the magnetization rate of the permanent magnet 25 tends to be low. Particularly, of the magnetic material inserted into the magnet insertion hole 21, a portion close to the interpolar portion tends to be insufficiently magnetized. Therefore, the magnetization rate of the permanent magnet 25 tends to be low, making it difficult to obtain high magnetic force.

It is also conceivable to insert a pre-magnetized permanent magnet 25 into the magnet insertion hole 21 of the rotor core 20, and then integrally mold the rotor core 20 and the shaft 10 with resin. However, since the molding temperature reaches 100 to 300° C., there is a possibility that the permanent magnet 25 will be demagnetized at high temperatures.

On the other hand, in the first embodiment, a magnetic body is magnetized singly to form a permanent magnet 25, and this permanent magnet 25 is incorporated into the rotor core 20 that is integrally formed with the shaft 10. Therefore, the entire magnetic body can be uniformly and sufficiently magnetized, and the magnetization rate of the permanent magnet 25 can be improved. Furthermore, since no heat is applied to the permanent magnet 25, demagnetization does not occur.

In particular, since the magnet insertion hole 21 is exposed at the end surface 20b of the rotor core 20 and the resin does not flow into the magnet insertion hole 21, the permanent magnet 25 is inserted into the magnet insertion hole 21 of the rotor core 20 after the molding process. can do.

More specifically, in the molding process, the contact surface 82g of the movable mold 82 comes into contact with the periphery of the magnet insertion hole 21 on the end surface 20b of the rotor core 20, so that the magnet insertion hole 21 cannot be exposed on the end surface 20b. can. Further, since the pin 82e suppresses the resin from flowing into the magnet insertion hole 21 of the rotor core 20, the inside of the magnet insertion hole 21 can be kept hollow. Therefore, as described above, the permanent magnets 25 can be inserted into the magnet insertion holes 21 of the rotor core 20 after the molding process.

Further, the permanent magnet 25 is inserted into the magnet insertion hole 21 from the end surface 20b side of the rotor core 20, that is, from the short shaft portion 10b side of the shaft 10. The shaft 10 is made of a magnetic material such as carbon steel, and a magnetic attraction force acts between it and the permanent magnet 25. However, since the short shaft portion 10b of the shaft 10 is shorter than the long shaft portion 10a, The influence of magnetic attraction force upon insertion of the permanent magnet 25 can be suppressed. This allows stable insertion of the permanent magnet 25.

<Effects of the embodiment>
As described above, the rotor 2 of the first embodiment includes the shaft 10, the rotor core 20 that surrounds the shaft 10 from the outside in the radial direction and has the magnet insertion hole 21, and the resin part 30 that holds the shaft 10 and the rotor core 20. and has. The rotor core 20 has axial end faces 20a and 20b. The magnet insertion hole 21 extends from the end surface 20a to the end surface 20b. On the end surface 20b of the rotor core 20, the magnet insertion hole 21 is not covered with the resin part 30.

Therefore, a singly magnetized permanent magnet 25 can be inserted into the magnet insertion hole 21 of the rotor core 20 formed integrally with the shaft 10. Since the permanent magnet 25 is magnetized singly, the magnetization rate of the permanent magnet 25 can be improved.

The rotor 2 further includes a second resin portion 32 that covers the end surface 20a of the rotor core 20, and the second resin portion 32 covers at least a portion of the magnet insertion hole 21 on the end surface 20a of the rotor core 20. Therefore, when the permanent magnet 25 is inserted into the magnet insertion hole 21 of the rotor core 20, the second resin portion 32 functions as a stopper for the permanent magnet 25. Therefore, the work of inserting the permanent magnet 25 can be simplified.

Further, the shaft 10 has a long shaft portion 10a and a short shaft portion 10b, and the permanent magnet 25 is inserted into the magnet insertion hole 21 from the short shaft portion 10b side. Therefore, the influence of the magnetic attractive force between the permanent magnet 25 and the shaft 10 is suppressed, and stable insertion of the permanent magnet 25 becomes possible.

Furthermore, since the third resin portion 33 is provided to cover the end surface 20b of the rotor core 20, the shaft 10 and the rotor core 20 can be held more firmly and integrally.

Furthermore, since the end surface 20b of the rotor core 20 further includes a non-magnetic material 34 that closes at least a portion of the magnet insertion hole 21, it is possible to reliably prevent the permanent magnet 25 from falling out of the magnet insertion hole 21.

In addition, since the pin 81e suppresses the resin from flowing into the magnet insertion hole 21 during the molding process, the inside of the magnet insertion hole 21 remains hollow even after the molding process, and therefore the permanent magnet 25 cannot be inserted into the magnet insertion hole 21. be able to. Note that in the finished product of the rotor 2, there is no resin around the permanent magnets 25 in the magnet insertion holes 21.

Variation example.
Next, a modification of the first embodiment will be described. FIG. 10 is a longitudinal sectional view showing a rotor 2A of a modified example. In the rotor 2A of the modified example, the non-magnetic material 34 (FIG. 4) is not provided on the end surface 20b of the rotor core 20, and the third resin portion 33 (FIG. 4) is also not provided.

The permanent magnet 25 can be fixed by fitting into the magnet insertion hole 21. Therefore, even if at least a portion of the magnet insertion hole 21 is not covered with the non-magnetic material 34, the fit can be adjusted so that the permanent magnet 25 does not fall out of the magnet insertion hole 21.

Furthermore, when the permanent magnet 25 is inserted into the magnet insertion hole 21, a magnetic attraction force acts between the permanent magnet 25 and the rotor core 20. This magnetic attraction force acts in a direction to prevent the permanent magnet 25 from jumping out of the magnet insertion hole 21 in the axial direction. Therefore, even if the magnet insertion hole 21 is not covered with the non-magnetic material 34, the permanent magnet 25 does not easily fall out from the magnet insertion hole 21.

Further, even if the third resin part 33 (FIG. 4) is not provided, the shaft 10 and the rotor core 20 can be integrally held by the first resin part 31 and the second resin part 32. .

Except for the above points, the rotor 2A of the modified example is configured similarly to the rotor 2 of the first embodiment. Note that although an example has been described here in which neither the nonmagnetic material 34 nor the third resin part 33 are provided on the end surface 20b of the rotor core 20, either one may be provided.

Also in this modification, as in the first embodiment, a singly magnetized permanent magnet 25 can be incorporated into the rotor core 20, so that the magnetization rate of the permanent magnet 25 can be improved. Furthermore, compared to Embodiment 1, the configuration of the rotor 2A can be simplified and manufacturing costs can be reduced.

Embodiment 2.
Next, a second embodiment will be described. FIG. 11 is a sectional view showing the rotor 2B of the second embodiment. The rotor 2B of the second embodiment is a consequent pole rotor in which magnetic poles and virtual magnetic poles are alternately arranged in the circumferential direction.

The rotor 2B has a plurality of magnet insertion holes 21 along the outer periphery 20c of the rotor core 20. The number of magnet insertion holes 21 is half the number of magnet insertion holes 21 (FIG. 3) in the first embodiment. The magnet insertion holes 21 are arranged at equal intervals in the circumferential direction. A flux barrier 22 for suppressing leakage magnetic flux is formed at both ends of each magnet insertion hole 21 in the circumferential direction.

A permanent magnet 25 is arranged in each magnet insertion hole 21. The permanent magnets 25 have magnetic pole faces of the same polarity (for example, N poles) facing the outer circumferential side. Therefore, a portion where magnetic flux flows in the radial direction occurs between adjacent permanent magnets 25 in the rotor core 20.

That is, in the rotor 2B, magnetic poles formed by the permanent magnets 25 and virtual magnetic poles formed by a part of the rotor core 20 are arranged alternately in the circumferential direction. Such a configuration is called a consequent pole type.

In FIG. 11, the pole center of the magnet magnetic pole is indicated by the symbol P1, and the pole center of the virtual magnetic pole is indicated by the symbol P2. Here, the magnet magnetic pole is the north pole and the virtual magnetic pole is the south pole, but the magnet magnetic pole may be the south pole and the virtual magnetic pole is the north pole.

The consequent pole type rotor 2B has half the number of permanent magnets 25 compared to the non-consequent pole type rotor 2 with the same number of poles (Fig. 3), so manufacturing costs can be significantly reduced. .

FIG. 12 is a diagram of the rotor 2B of Embodiment 2 viewed from the anti-load side. The rotor 2B includes a non-magnetic material 36 and a third resin portion 35 on the end surface 20b of the rotor core 20.

The same number of nonmagnetic bodies 36 as the magnet insertion holes 21 are provided. The length of each non-magnetic body 36 in the circumferential direction is longer than the length of the magnet insertion hole 21 in the circumferential direction. Each non-magnetic material 36 extends in the circumferential direction along the outer periphery 20c of the rotor core 20 so as to cover at least a portion of the magnet insertion hole 21.

In the example shown in FIG. 12, the nonmagnetic material 36 exposes the inner peripheral side of the circumferential center of the magnet insertion hole 21 and the flux barrier 22, but it may cover the entire magnet insertion hole 21. That is, the non-magnetic material 36 only needs to cover at least a portion of the magnet insertion hole 21 so that the permanent magnet 25 inside the magnet insertion hole 21 does not fall out.

The third resin portion 35 has an outer periphery 35a and an inner periphery 35d. The shaft 10 is fixed to the inner circumference 35d of the third resin portion 35. The outer periphery 35a of the third resin portion 35 extends so that the distance from the central axis Ax changes in the circumferential direction.

Specifically, the distance from the center axis Ax to the outer periphery 35a reaches a maximum value L1 at the first portion 35b corresponding to the pole center P2 (FIG. 11) of the virtual magnetic pole, and the distance from the center axis Ax to the outer circumference 35a reaches the maximum value L1 at the first portion 35b corresponding to the pole center P2 (FIG. 11) of the virtual magnetic pole. The corresponding second portion 35c has the minimum value L2.

In the consequent pole rotor 2A, since the permanent magnets 25 are not present in the virtual magnetic poles, even if the third resin part 35 is formed close to the outer periphery of the rotor core 20, the permanent magnets 25 cannot be inserted into the magnet insertion holes 21. does not interfere with

FIG. 13 is a longitudinal cross-sectional view showing the rotor 2B of the second embodiment. As in the first embodiment, a first resin portion 31 is provided between the rotor core 20 and the shaft 10, and a second resin portion 32 is provided on the end surface 20a of the rotor core 20. The third resin part 35 is formed integrally with the first resin part 31 and the second resin part 32.

FIGS. 14(A) and 14(B) are diagrams for explaining an example of a method of fixing the non-magnetic material 36. As shown in FIG. 14(A), the non-magnetic material 36 has an extending portion 36a that extends in the circumferential direction along the outer periphery of the rotor core 20 (FIG. 12), and a non-magnetic material 36 that extends from both ends of the extending portion 36a to the rotor core 20. It has a pair of leg portions 36b extending in the axial direction toward the rotor core 20, and a claw portion 36c protruding from the lower end of the leg portion 36b in parallel with the end surface 20b of the rotor core 20.

The third resin portion 35 has a pair of convex portions 35e at positions that sandwich the non-magnetic material 36 from both sides in the longitudinal direction. As shown in FIG. 14(B), an engagement hole 35f that engages with the claw portion 36c of the non-magnetic material 36 is formed in the convex portion 35e.

When attaching the non-magnetic material 36 to the third resin part 35, as shown by arrow F in FIG. Push it in. Each claw portion 36c of the non-magnetic body 36 comes into contact with the convex portion 35e, and the pair of leg portions 36b are elastically deformed so as to approach each other. When the claw portion 36c engages with the engagement hole 35f, the leg portion 36b returns to the state before elastic deformation, and the claw portion 36c becomes unable to come out from the engagement hole 35f. Thereby, the non-magnetic material 36 is fixed to the third resin part 35.

FIG. 15 is a diagram for explaining another example of the method of fixing the non-magnetic material 36. As shown in FIG. 15, the non-magnetic material 36 includes an extending portion 36a that extends in the circumferential direction along the outer periphery of the rotor core 20 (FIG. 12), and an axial direction toward the rotor core 20 from both ends of the extending portion 36a. The rotor core 20 has a pair of leg portions 36b extending in the direction, and a pedestal portion 36d extending parallel to the end surface 20b of the rotor core 20 from the lower end of the leg portion 36b. A hole 36f is formed in the pedestal portion 36d, passing through the pedestal portion 36d in the axial direction.

The third resin part 35 has a post 35g that projects in the axial direction at a position corresponding to the hole 36f of the pedestal part 36d of the non-magnetic body 36.

When attaching the non-magnetic material 36 to the third resin part 35, the pedestal part 36d of the non-magnetic material 36 is placed on the third resin part 35, and the post 35g is engaged with the hole part 36f. Thereafter, the end of the post 35g protruding from the hole 36f is welded to form an engaging portion 35h. By forming the engaging portion 35h at the end of the post 35g, the pedestal portion 36d is prevented from coming off the post 35g. Thereby, the non-magnetic material 36 is fixed to the third resin part 35.

Note that in FIGS. 14A, 14B and 15, the extending portion 36a of the non-magnetic material 36 is axially away from the end surface 20b of the rotor core 20. The axial distance from the end surface 20a of the rotor core 20 to the extension portion 36a may be any distance that can prevent the permanent magnet 25 from protruding from the magnet insertion hole 21 (for example, less than the axial length of the permanent magnet 25).

However, if the permanent magnet 25 protrudes from the magnet insertion hole 21 in the axial direction, the magnetic flux emitted from the protruding portion of the permanent magnet 25 becomes a leakage magnetic flux and does not contribute to the generation of the driving force, so it is desirable that the amount of protrusion is small. Therefore, it is desirable that the axial distance from the end surface 20b of the rotor core 20 to the extending portion 36a of the non-magnetic material 36 be as small as possible.

Further, the method of fixing the non-magnetic material 36 to the third resin part 35 is not limited to the fixing methods shown in FIGS. 14(A), (B) and FIG. 15, but other fixing methods may be used.

Except for the above points, the rotor 2B of the second embodiment is configured similarly to the rotor 2 of the first embodiment.

Since the rotor 2B of the second embodiment is of the consequent pole type, the third resin portion 35 can be formed close to the outer periphery of the rotor core 20 at the position corresponding to the virtual magnetic pole. Therefore, the engaging portion between the third resin portion 35 and the non-magnetic material 36 can be formed at a position close to the non-magnetic material 36, and the non-magnetic material 36 can be firmly fixed. Moreover, since the non-magnetic material 36 can be fixed to the third resin part 35 at both ends in its extending direction, the non-magnetic material 36 can be fixed more firmly.

<Air conditioner>
Next, an air conditioner to which the electric motor 1 of each of the embodiments and modifications described above can be applied will be described. FIG. 16(A) is a diagram showing the configuration of an air conditioner 500 to which the electric motor 1 of Embodiment 1 is applied. The 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 blower 510. Outdoor blower 510 is, for example, a propeller fan. The outdoor blower 510 includes an impeller 511 and an electric motor 1A that drives the impeller.

The indoor unit 502 includes an evaporator 506 and an indoor blower 520. Indoor blower 520 is, for example, a cross flow fan. The indoor blower 520 includes an impeller 521 and an electric motor 1B that drives the impeller.

FIG. 16(B) is a cross-sectional view of the outdoor unit 501. The electric motor 1A is supported by a frame 509 disposed within a housing 508 of the outdoor unit 501. An impeller 511 is attached to the 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 in the condenser 505 is released outdoors by air blowing from the outdoor blower 510.

In the indoor blower 520 (FIG. 16(A)), the impeller 521 is rotated by the electric motor 1B to blow air into the room. During cooling operation of the air conditioner 500, the air from which heat has been removed when the refrigerant evaporates in the evaporator 506 is blown into the room by the indoor blower 520.

Since the

electric motors

1A and 1B are configured with the electric motor 1 of Embodiment 1, they have high electric motor efficiency due to the high magnetic force of the permanent magnet 25. Therefore, the operating efficiency of the outdoor blower 510 and the indoor blower 520 can be improved, and thereby the operating efficiency of the air conditioner 500 can be improved.

The

electric motors

1A and 1B are not limited to the electric motor 1 of the first embodiment, but may be a modified example or the electric motor of the second embodiment. Moreover, although the electric motor of each embodiment and modification example is used for both the outdoor blower 510 and the indoor blower 520 here, it may be used for only either one.

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 rotor, 5 stator, 6 molded stator, 10 shaft, 10a long shaft part, 10b short shaft part, 20 rotor core, 20a end face (first end face), 20b End face (No. 2 end face), 21 magnet insertion hole, 22 flux barrier, 25 permanent magnet, 31 first resin part, 32 second resin part, 33 third resin part, 33 non-magnetic material, 33c engaging part, 34 Projection part, 35 third resin part, 35h engaging part, 36 non-magnetic material, 50 stator core, 51 yoke, 52 teeth, 53 slot, 55 coil, 60 mold resin part, 80 mold, 81 Fixed mold, 82 Movable mold, 500 Air conditioner, 501 Outdoor unit, 502 Indoor unit, 510 Outdoor blower, 511 Impeller, 520 Indoor blower, 521 Impeller.

Claims

shaft and
a rotor core surrounding the shaft from the outside in the radial direction and having a magnet insertion hole;
a permanent magnet placed in the magnet insertion hole;
a resin part including a first resin part located between the shaft and the rotor core, and a resin part holding the shaft and the rotor core;
The rotor core has a first end surface and a second end surface in the axial direction of the shaft,
The magnet insertion hole extends from the first end surface to the second end surface,
The rotor wherein the magnet insertion hole is not covered by the resin portion on at least one of the first end surface and the second end surface.
a second resin portion on the first end surface of the rotor core;
The rotor according to claim 1, wherein the second resin portion covers at least a portion of the magnet insertion hole on the first end surface.
The shaft has a long shaft portion that projects in the axial direction from the first end surface of the rotor core, and a short shaft portion that projects in the axial direction from the second end surface of the rotor core,
The rotor according to claim 1 or 2, wherein the length of the long shaft portion is longer than the length of the short shaft portion.
The rotor according to any one of claims 1 to 3, wherein no resin is provided around the permanent magnet inside the magnet insertion hole.
The rotor according to any one of claims 1 to 4, further comprising a non-magnetic material that closes at least a portion of the magnet insertion hole on the second end surface of the rotor core.
The rotor according to claim 5, wherein the non-magnetic material is fixed to the first resin part by welding.
The rotor according to claim 5 or 6, wherein the non-magnetic material has an engaging portion that engages with a part of the magnet insertion hole.
The rotor according to any one of claims 1 to 7, further comprising a third resin portion on the second end surface of the rotor core.
The rotor according to claim 8, wherein the permanent magnet constitutes a magnetic pole, and a portion of the rotor core constitutes a virtual magnetic pole.
The distance from the center of the shaft to the outer periphery of the third resin portion is L1 at the pole center of the virtual magnetic pole, and L2 at the pole center of the magnet magnetic pole, and L1>L2 holds true. rotor.
The second end surface of the rotor core further includes a non-magnetic material that blocks at least a portion of the magnet insertion hole,
The rotor according to claim 9 or 10, wherein the non-magnetic material has an engaging part that engages with the third resin part.
The non-magnetic material extends along the outer periphery of the rotor core,
The rotor according to claim 11, wherein the engaging portions are provided at both ends of the non-magnetic material in the extending direction.
A rotor according to any one of claims 1 to 12,
and an annular stator surrounding the rotor.
The electric motor according to claim 13;
an impeller attached to the 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 includes the blower according to claim 14. An air conditioner.
A process of magnetizing a magnetic material to make it a permanent magnet,
a step of integrally molding a rotor core having a magnet insertion hole and a shaft with resin;
inserting the permanent magnet into the magnet insertion hole of the rotor core,
In the step of integrally molding the rotor core and the shaft with resin, the magnet insertion hole is exposed on at least one of the first end surface and the second end surface of the rotor core in the axial direction of the shaft. Manufacture of a rotor Method.
After the step of inserting the permanent magnet,
The method for manufacturing a rotor according to claim 16, further comprising the step of attaching a non-magnetic material to the rotor core to cover at least a portion of the magnet insertion hole.