WO2020129207A1

WO2020129207A1 - Rotor, electric motor, blower, air-conditioning device, and method for manufacturing rotor

Info

Publication number: WO2020129207A1
Application number: PCT/JP2018/046931
Authority: WO
Inventors: 諒伍 ▲高▼橋; 洋樹麻生; 貴也下川
Original assignee: 三菱電機株式会社
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-06-25
Also published as: JPWO2020129207A1; JP7012878B2

Abstract

Provided is a rotor comprising: a shaft; an annular rotor core surrounding the shaft from radially outward of a center at the central axis of the shaft; a main magnet attached to the rotor core; a sensor magnet disposed on one side of the main magnet in the direction of the central axis; and a resin portion which is disposed on the rotor core and holds the sensor magnet. The resin portion has a hollow portion in which a part of the sensor magnet is exposed.

Description

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

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

The rotor of the electric motor has an annular sensor magnet used to detect the rotational position of the rotor. The sensor magnet is attached to the rotor core via a resin pedestal (for example, see Patent Document 1).

JP-A-2014-050309 (see FIG. 6)

However, if the sensor magnet is attached using the pedestal, the number of parts of the rotor increases and the manufacturing cost increases.

The present invention has been made to solve the above problems, and an object of the present invention is to reduce the number of rotor parts and manufacturing costs.

The rotor of the present invention includes a shaft, an annular rotor core that surrounds the shaft from the outside in the radial direction centered on the central axis of the shaft, a main magnet attached to the rotor core, and in the direction of the central axis. A sensor magnet is provided on one side of the main magnet, and a resin portion is provided on the rotor core and holds the sensor magnet. The resin portion has a hollow portion where a part of the sensor magnet is exposed.

In the rotor of the present invention, the resin portion has a hollow portion where a part of the sensor magnet is exposed. Therefore, a rotor is manufactured by arranging a rotor core to which a main magnet is attached and a shaft in a molding die, holding a sensor magnet by a jig of the molding die, and integrally molding the resin. You can Since it is not necessary to attach a pedestal for the sensor magnet to the rotor, the number of parts of the rotor can be reduced and the manufacturing cost can be reduced.

FIG. 3 is a partial cross-sectional view showing the electric motor of the first embodiment. FIG. 3 is a diagram showing a stator core according to the first embodiment. FIG. 3 is a vertical sectional view showing the rotor of the first embodiment. FIG. 3 is an enlarged vertical sectional view showing the rotor of the first embodiment. FIG. 3 is a sectional view showing the rotor of the first embodiment. FIG. 3 is a diagram showing a rotor core according to the first embodiment. FIG. 3 is a front view showing the rotor of the first embodiment. 3 is a rear view showing the rotor according to the first embodiment. FIG. FIG. 3 is a vertical sectional view showing the molding die according to the first embodiment. 6 is a flowchart showing a rotor manufacturing process in the first embodiment. FIG. 3 is a schematic diagram showing a pin, a rotor core, and a sensor magnet of the molding die according to the first embodiment. FIG. 3 is a schematic view showing an enlarged tip end portion of a pin of the molding die according to the first embodiment. FIG. 7 is a cross-sectional view showing a rotor according to a modified example of the first embodiment. It is a figure (A) showing an example of composition of an air harmony device to which a motor of Embodiment 1 and each modification is applicable, and a sectional view (B) showing an outdoor unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
<Structure of electric motor 1>
1 is a vertical sectional view showing an electric motor 1 according to Embodiment 1 of the present invention. The electric motor 1 is a brushless DC motor used in, for example, a blower of an air conditioner and driven by an inverter. The electric motor 1 is an IPM (Interior Permanent Magnet) motor in which the main magnet 25 is embedded in the rotor 2.

The electric motor 1 has a rotor 2 having a shaft 11 and a mold stator 50 surrounding the rotor 2. The mold stator 50 has an annular stator 5 that surrounds the rotor 2 and a mold resin portion 55 that covers the stator 5. The shaft 11 is the rotation axis of the rotor 2.

In the following description, the direction of the central axis C1 of the shaft 11 will be referred to as the "axial direction". The circumferential direction (indicated by the arrow S in FIG. 2 etc.) about the central axis C1 of the shaft 11 is referred to as "circumferential direction". The radial direction centered on the central axis C1 of the shaft 11 is referred to as the “radial direction”. A sectional view taken along a section parallel to the axial direction is called a vertical sectional view.

The shaft 11 protrudes from the mold stator 50 to the left side in FIG. 1, and an impeller 505 (FIG. 14A) of a blower is attached to the attachment portion 11a formed on the protrusion. Therefore, the protruding side (left side in FIG. 1) of the shaft 11 is referred to as “load side”, and the opposite side (right side in FIG. 1) is referred to as “anti-load side”.

<Structure of mold stator 50>
As described above, the mold stator 50 has the stator 5 and the mold resin portion 55. The stator 5 surrounds the rotor 2 from the outside in the radial direction. The stator 5 has a stator core 51, an insulating portion (insulator) 52 provided in the stator core 51, and a coil (winding) 53 wound around the stator core 51 via the insulating portion 52. ..

The mold resin portion 55 is formed of a thermosetting resin such as BMC (bulk molding compound). The mold resin portion 55 has a bearing support portion 55a on one side (here, an anti-load side) in the axial direction, and has an opening portion 55b on the other side (here, a load side). The rotor 2 is inserted into the hollow portion 56 inside the mold stator 50 through the opening 55b.

A metal bracket 15 is attached to the opening 55b of the mold resin portion 55. The bracket 15 holds one bearing 12 that supports the shaft 11. A cap 14 is attached to the outside of the bracket 15 to prevent water and the like from entering. The bearing support portion 55a of the mold resin portion 55 has a cylindrical inner peripheral surface, and the other bearing 13 that supports the shaft 11 is held on this inner peripheral surface.

FIG. 2 is a plan view showing the stator core 51. The stator core 51 is formed by stacking a plurality of laminated elements in the axial direction and integrally fixing them by caulking, welding, bonding or the like. The laminated element is, for example, a magnetic steel sheet. The stator core 51 has a yoke 511 extending annularly in the circumferential direction centered on the central axis C1 and a plurality of teeth 512 extending radially inward from the yoke 511. Teeth tips 513 on the radially inner side of the teeth 512 face the outer peripheral surface of the rotor 2 (FIG. 1 ). The number of teeth 512 is twelve here, but is not limited to this.

The stator core 51 has a configuration in which a plurality of (here, 12) divided cores 51A are divided for each tooth 512. The split core 51A is split by a split surface 514 formed on the yoke 511. The dividing surface 514 extends radially outward from the inner peripheral surface of the yoke 511. A plastically deformable thin portion 515 is formed between the end of the dividing surface 514 and the outer peripheral surface of the yoke 511. By the plastic deformation of the thin portion 515, the stator core 51 can be expanded in a band shape.

With this configuration, the coil 53 can be wound around the tooth 512 in a state where the stator core 51 is expanded in a strip shape. After winding the coil 53, the band-shaped stator cores 51 are combined in an annular shape, and the ends (shown by the symbol W in FIG. 2) are welded. The stator core 51 is not limited to a combination of such split cores, and may be integrally formed.

Returning to FIG. 1, the insulating portion 52 is formed of a thermoplastic resin such as PBT (polybutylene terephthalate). The insulating portion 52 is formed by integrally molding a thermoplastic resin with the stator core 51 or by assembling a molded body of the thermoplastic resin to the stator core 51.

The coil 53 is a magnet wire wound around the tooth 512 (FIG. 2) via the insulating portion 52. The insulating portion 52 has wall portions inside and outside the coil 53 in the radial direction, and guides the coil 53 from both sides in the radial direction.

A board 6 is arranged on one side in the axial direction with respect to the stator 5 (here, an anti-load side). The board 6 is a printed board on which a drive circuit 60 such as a power transistor for driving the electric motor 1 and a hall element are mounted, and lead wires 61 are wired. The lead wire 61 of the substrate 6 is drawn out of the electric motor 1 from a lead wire lead-out component 62 attached to the outer peripheral portion of the mold resin portion 55.

The bracket 15 is press-fitted into an annular portion provided on the outer peripheral edge of the opening 55b of the mold resin portion 55. The bracket 15 is formed of a conductive metal, such as a galvanized steel plate, but is not limited thereto. The cap 14 is attached to the outside of the bracket 15 and prevents water and the like from entering the bearing 12.

<Structure of rotor 2>
FIG. 3 is a vertical sectional view showing the rotor 2. FIG. 4 is a vertical cross-sectional view showing a part of the rotor 2 in an enlarged manner. FIG. 5 is a cross-sectional view taken along the line 5-5 shown in FIG.

As shown in FIG. 5, the rotor 2 includes a shaft 11 that is a rotation axis, a rotor core 20 that is provided radially outward from the shaft 11, and a rotor core 20 that is embedded in the rotor core 20. It has a plurality of main magnets 25 and a resin portion 3 provided between the shaft 11 and the rotor core 20. The number of main magnets 25 is five here. The main magnet 25 is also referred to as a drive magnet or a rotor magnet.

The shaft 11 is made of a magnetic material such as carbon steel (S45C), but may be made of a non-magnetic material such as stainless steel. The shaft 11 has a circular cross section centered on the above-mentioned central axis C1.

FIG. 6 is a diagram showing the rotor core 20. The rotor core 20 is an annular member centered on the central axis C1. The rotor core 20 has an outer circumference 20a and an inner circumference 20b, and the inner circumference 20b faces the shaft 11 with a distance. The rotor core 20 is formed by laminating a plurality of laminated elements in the axial direction and fixing them by crimping, welding, or bonding. The laminated element is, for example, an electromagnetic steel plate and has a thickness of 0.1 mm to 0.7 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 the same distance from the central axis C1. The number of magnet insertion holes 21 is five here. The magnet insertion hole 21 is formed along the outer periphery 20a of the rotor core 20 and penetrates the rotor core 20 in the axial direction.

Returning to FIG. 5, the main magnet 25 is inserted into each magnet insertion hole 21. The main magnet 25 has a flat plate shape, and a cross-sectional shape orthogonal to the axial direction is a rectangular shape. The main magnet 25 is a rare earth magnet, and more specifically, a neodymium sintered magnet containing Nd(neodymium)-Fe(iron)-B(boron) as a main component. Flux barriers 22 that are voids are formed at both ends of the magnet insertion hole 21 in the circumferential direction. The flux barrier 22 suppresses a short circuit of magnetic flux between the adjacent main magnets 25.

The main magnet 25 is arranged with the same magnetic poles (for example, N poles) facing the outer peripheral side of the rotor core 20. In the rotor core 20, a magnetic pole (for example, an S pole) opposite to the main magnet 25 is formed in a region between the main magnets 25 that are adjacent to each other in the circumferential direction.

Therefore, the rotor 2 has five first magnetic poles P1 (for example, N poles) and five second magnetic poles P2 (for example, S poles) arranged alternately in the circumferential direction. Therefore, the rotor 2 has 10 magnetic poles. The ten magnetic poles P1 and P2 of the rotor 2 are arranged at equal angular intervals in the circumferential direction with a pole pitch of 36 degrees (360 degrees/10).

That is, of the 10 magnetic poles P1 and P2 of the rotor 2, half the five magnetic poles (first magnetic pole P1) are formed by the main magnet 25, but the remaining five magnetic poles (second magnetic pole P2). Is formed by the rotor core 20. Such a configuration is called a consequent pole type. Hereinafter, when simply referred to as a “magnetic pole”, it includes both the first magnetic pole P1 and the second magnetic pole P2.

The outer circumference 20a of the rotor core 20 has a so-called flower circle shape in a cross section orthogonal to the axial direction. In other words, the outer circumference 20a of the rotor core 20 has the maximum outer diameter at the pole centers of the magnetic poles P1 and P2 (that is, the center in the circumferential direction) and the minimum outer diameter at the pole gap M, and It has an arc shape up to M. The outer periphery 20a of the rotor core 20 is not limited to a flower circle shape, but may be a circular shape. On the other hand, the inner circumference 20b of the rotor core 20 has a circular shape in a cross section orthogonal to the axial direction.

With the consequent pole type rotor 2, the number of main magnets 25 can be halved compared to a non-consequent pole type rotor with the same number of poles. Since the number of expensive main magnets 25 is small, the manufacturing cost of the rotor 2 is reduced.

The number of poles of the rotor 2 is 10 here, but the number of poles may be an even number of 4 or more. Although one main magnet 25 is arranged in one magnet insertion hole 21 here, two or more main magnets 25 may be arranged in one magnet insertion hole 21. The first magnetic pole P1 may be the S pole and the second magnetic pole P2 may be the N pole.

In the consequent pole type rotor 2, since there is no main magnet in the second magnetic pole P2, magnetic flux easily flows into the shaft 11. By providing the resin portion 3 which is a non-magnetic material between the shaft 11 and the rotor core 20, magnetic flux leakage in the consequent pole type rotor 2 is suppressed.

In the rotor core 20, a plurality of core holes 26 are formed inside the magnet insertion hole 21 in the radial direction. The number of core holes 26 is, for example, half the number of poles, and is five here. The core hole 26 is for positioning a rotor core 20 by engaging a pin 77 of a molding die 9 (FIG. 9) described later.

Each core hole 26 is equidistant from the central axis C1 and has the same relative position to the closest magnetic pole. Here, each core hole 26 is formed radially inside the pole center of the first magnetic pole P1. With such an arrangement, any core hole 26 of the rotor core 20 can be engaged with the pin 77 of the molding die 9.

Here, each core hole 26 is formed radially inside the pole center of the first magnetic pole P1, but it may be formed radially inside the pole center of the second magnetic pole P2. The cross-sectional shape of the core hole 26 is circular here, but may be rectangular, for example, or may be another cross-sectional shape (see FIG. 17 described later).

In the consequent pole type rotor 2, since the main magnet does not exist in the second magnetic pole P2, the magnetic flux from the first magnetic pole P1 is easily disturbed. The disturbance of the magnetic flux leads to an imbalance of the magnetic force, which causes vibration or noise. By arranging the core hole 26 at the pole center of the first magnetic pole P1 or the second magnetic pole P2, the flow of the magnetic flux can be adjusted, and thus the vibration and noise of the electric motor 1 can be reduced.

The weight balance in the circumferential direction of the rotor core 20 is improved by making the number of core holes 26 half the number of poles and making the circumferential position of each core hole 26 coincide with the pole center of the first magnetic pole P1. However, the number of core holes 26 is not limited to half the number of poles.

The inner periphery 20b of the rotor core 20 has a circular shape in a cross section orthogonal to the axial direction, but the portion corresponding to the core hole 26 is a protrusion 20c that protrudes radially inward. The protruding portion 20c is formed in an arc shape along the edge of the core hole 26.

The resin portion 3 is provided between the shaft 11 and the rotor core 20. The resin portion 3 connects the shaft 11 and the rotor core 20 and has electrical insulation. The resin portion 3 is preferably formed of a thermoplastic resin such as PBT.

The resin portion 3 connects the annular inner ring portion 31 that contacts the outer circumference of the shaft 11, the annular outer ring portion 33 that contacts the inner circumference 20 b of the rotor core 20, and the inner ring portion 31 and the outer ring portion 33. And a plurality of ribs 32. The ribs 32 are arranged at equal intervals in the circumferential direction around the central axis C1. The number of ribs 32 is, for example, half of the number of poles, and is five here.

The shaft 11 penetrates the inner ring portion 31 of the resin portion 3 in the axial direction. The outer ring portion 33 supports the rotor core 20 from the inner circumference 20b side. The outer ring portion 33 has, at a position corresponding to the core hole 26, an arc-shaped edge portion 34 that projects radially inward along the projecting portion 20 c of the rotor core 20.

The ribs 32 are arranged at equal intervals in the circumferential direction and extend radially outward from the inner ring portion 31. A cavity 35 is formed between the ribs 32 that are adjacent to each other in the circumferential direction. The cavity 35 preferably penetrates the rotor 2 in the axial direction.

Here, the number of ribs 32 is half the number of poles, and the circumferential position of each rib 32 is coincident with the pole center of the second magnetic pole P2. Therefore, the weight balance of the rotor 2 in the circumferential direction is improved. However, the number of ribs 32 is not limited to half the number of poles. Further, the circumferential position of the rib 32 may coincide with the pole center of the first magnetic pole P1.

Since the resin portion 3 has electric insulation, the rotor core 20 and the shaft 11 are electrically insulated, and as a result, the current flowing from the rotor core 20 to the shaft 11 (referred to as axial current) is suppressed. As a result, electrolytic corrosion of the bearings 12 and 13 (that is, damage to the raceways of the inner and outer rings and the rolling surfaces of the rolling elements) is suppressed.

The resonance frequency (natural frequency) of the rotor 2 can be adjusted by changing the radial length and the circumferential width of the rib 32 of the resin portion 3. For example, the shorter the rib 32 is and the wider the rib 32 is, the higher the resonance frequency of the rotor 2 is. The longer the rib 32 is and the narrower the rib 32 is, the lower the resonance frequency of the rotor 2 is. As described above, since the resonance frequency of the rotor 2 can be adjusted by the size of the rib 32, the torsional resonance between the electric motor 1 and the impeller attached to the electric motor 1 and the resonance of the entire unit including the blower are suppressed. Noise can be suppressed.

As shown in FIG. 4, the resin portion 3 includes an end surface portion 38 that covers one end surface (here, an end surface on the load side) of the rotor core 20 in the axial direction, and the other end surface (here, the other end surface of the rotor core 20 in the axial direction). End face portion 39 that covers the end face on the counter load side). The end surface portion 38 does not need to completely cover one end surface of the rotor core 20, but may cover at least a part thereof. The same applies to the end face portion 39.

FIG. 7 is a view of the rotor 2 viewed from the load side, that is, a front view. As described above, the end surface portion 38 covers one end surface of the rotor core 20 in the axial direction. Further, the end surface portion 38 has a hole portion (referred to as a resin hole portion) 37 at a position corresponding to the core hole 26 of the rotor core 20. The resin hole portion 37 is a hole formed by the pin 77 of the molding die 9 engaging with the core hole 26 of the rotor core 20 (therefore, the resin does not enter).

Note that, here, since the pins 77 of the molding die 9 engage with all of the five core holes 26, the same number of resin hole portions 37 as the core holes 26 are formed in the end face portion 38. However, when the number of the pins 77 of the molding die 9 is smaller than the number of the core holes 26, the resin enters the core holes 26 which are not engaged with the pins 77, so that the same number of resin hole portions as the number of the pin 77 are provided. 37 is formed.

FIG. 8 is a view of the rotor 2 viewed from the anti-load side, that is, a rear view. The end face portion 39 covers the other end face of the rotor core 20 in the axial direction and holds the annular sensor magnet 4 described below with its surface exposed. However, the end surface portion 39 may completely cover the sensor magnet 4.

Returning to FIG. 4, the sensor magnet 4 is arranged so as to face the rotor core 20 in the axial direction, and is held from the periphery by the end face portion 39. The sensor magnet 4 is an annular member centered on the central axis C1 and has the same number of magnetic poles as the rotor 2 (here, 10).

The magnetic flux of the sensor magnet 4 is detected by the Hall element as a magnetic sensor mounted on the board 6, and the circumferential position (rotational position) of the rotor 2 is thereby detected. The sensor magnet 4 is also referred to as a position detecting main magnet.

A protrusion 41 is formed on the inner peripheral surface 4b of the sensor magnet 4 so as to protrude inward in the radial direction. The protrusion 41 is held by the end surface portion 39 of the resin portion 3 from both sides in the axial direction, and prevents the sensor magnet 4 from falling off in the axial direction.

Moreover, the end surface portion 39 of the resin portion 3 has an interposition portion 39 a interposed between the rotor core 20 and the sensor magnet 4. The interposition part 39a keeps the rotor core 20 and the sensor magnet 4 out of contact with each other. As a result, the influence of the main magnet 25 on the magnetic flux of the sensor magnet 4 is suppressed, and the accuracy of magnetic flux detection by the Hall element of the substrate 6 is improved. ‥

The resin portion 3 has a cavity portion 36 at a position corresponding to the core hole 26 of the rotor core 20. The core hole 26 penetrates the rotor core 20 in the axial direction, and the hollow portion 36 of the resin portion 3 is formed so as to overlap the core hole 26 in the axial direction. In other words, the hollow portion 36 of the resin portion 3 is continuous with the core hole 26 of the rotor core 20 in the axial direction.

The cavity portion 36 of the resin portion 3 is a portion where the holding portion 78 (FIG. 9) provided at the tip of the pin 77 of the molding die 9 is provided when the shaft 11 and the rotor core 20 are integrally molded with resin. is there. When the rotor 2 is taken out of the molding die 9, the cavity 36 corresponding to the holding portion 78 is formed in the resin portion 3.

A part of the surface of the sensor magnet 4 on the rotor core 20 side (that is, the surface opposite to the substrate 6) 4a and the inner peripheral surface 4b are exposed in the cavity 36. Exposure is the appearance of a surface in a space. In other words, a part of the surface 4a of the sensor magnet 4 on the rotor core 20 side and the inner peripheral surface 4b are not covered with the resin portion 3.

The resin hole portion 37 of the resin portion 3, the core hole 26 of the rotor core 20, and the cavity portion 36 of the resin portion 3 are aligned in the axial direction and are continuous with each other. Therefore, when the rotor 2 is viewed from the load side, a part of the sensor magnet 4 is visible as shown in FIG.

Note that, here, the radially inner portion of the sensor magnet 4 is exposed to the cavity portion 36, but the radially outer portion of the sensor magnet 4 may be exposed to the cavity portion 36.

<Method of manufacturing rotor 2>
Next, a method of manufacturing the rotor 2 will be described. The rotor 2 is manufactured by integrally molding the shaft 11, the rotor core 20, the main magnet 25, and the sensor magnet 4 with resin.

FIG. 9 is a vertical sectional view showing the molding die 9. The molding die 9 has a fixed die (lower die) 7 and a movable die (upper die) 8. The fixed mold 7 and the movable mold 8 have mold mating surfaces 75 and 85 facing each other.

The fixed mold 7 has a shaft insertion hole 71 into which one end of the shaft 11 is inserted, a rotor core insertion portion 73 into which the rotor core 20 is inserted, and an axial end surface of the rotor core 20 (here, a lower surface). To the inner surface of the rotor core 20, the contact portion 70 that contacts the outer peripheral portion of the axial end surface of the rotor core 20, the cylindrical portion 74 that faces the outer peripheral surface of the shaft 11, and the inner surface of the rotor core 20. And a pin (projection) 77 as a jig protruding from the facing surface 72.

A holding portion 78 that holds the sensor magnet 4 from the inner peripheral side is provided at the tip of the pin 77. The pin 77 is a portion that engages with the core hole 26 of the rotor core 20 and positions the rotor core 20. A holding portion 78 for holding the sensor magnet 4 is provided at the tip of the pin 77.

The number of the pins 77 is equal to the number (for example, 5) of the core holes 26 of the rotor core 20 here, and is arranged in the same manner as the core holes 26. However, the number of pins 77 may be smaller than the number of core holes 26. In order to hold the sensor magnet 4 in a stable state, the number of the pins 77 is preferably two or more, and more preferably three or more.

The movable mold 8 includes a shaft insertion hole 81 into which the other end of the shaft 11 is inserted, a rotor core insertion portion 83 into which the rotor core 20 is inserted, and an axial end surface of the rotor core 20 (here, an upper surface). ), a cylindrical portion 84 that faces the periphery of the shaft 11, and a cavity forming portion 86 that is inserted inside the rotor core 20.

FIG. 10 is a flowchart showing the manufacturing process of the rotor 2. First, magnetic steel sheets are laminated and fixed by caulking or the like to form the rotor core 20 (step S101). Next, the main magnet 25 is inserted into the magnet insertion hole 21 of the rotor core 20 (step S102).

Next, the rotor core 20 and the shaft 11 are mounted on the molding die 9 and integrally molded with resin such as PBT. Specifically, the shaft 11 is inserted into the shaft insertion hole 71 of the fixed mold 7, and the rotor core 20 is inserted into the rotor core insertion portion 73 (step S103). At this time, the pin 77 of the fixed mold 7 engages with the core hole 26 of the rotor core 20. The engagement between the pin 77 and the core hole 26 positions the rotor core 20.

As described above, since the plurality of core holes 26 of the rotor core 20 are equidistant from the central axis C1 and have the same relative positions with respect to the closest magnetic poles, even if the circumferential position of the rotor core 20 is changed, The hole 26 and the pin 77 can be engaged with each other. The pin 77 penetrates the core hole 26 of the rotor core 20 and projects upward.

Next, the sensor magnet 4 is placed on the holding portion 78 at the tip of the pin 77 (step S104). FIG. 11 is a diagram showing the shaft 11, the rotor core 20, and the holding portion 78. FIG. 12 is a diagram showing the shape of the holding portion 78. As shown in FIG. 11, the holding portion 78 formed at the tip of the pin 77 holds the sensor magnet 4 from the inner peripheral side.

As shown in FIG. 12, the holding portion 78 has an end face 78a orthogonal to the protruding direction of the pin 77 (that is, the axial direction of the shaft 11), and the sensor magnet 4 is axially positioned by this end face 78a. Further, the holding portion 78 has a protrusion 79 that contacts the protrusion 41 of the sensor magnet 4 from the inside in the radial direction, and the protrusion 79 positions the sensor magnet 4 in the radial direction.

In this way, with the shaft 11 and the rotor core 20 installed in the fixed mold 7 and the sensor magnet 4 placed on the holding portion 78, the movable mold 8 is lowered as shown by the arrow in FIG. , The

die mating surfaces

75 and 85 are brought into contact with each other. With the

die mating surfaces

75 and 85 in contact with each other, a gap is formed between the lower surface of the rotor core 20 and the facing surface 72, and a gap is also formed between the upper surface of the rotor core 20 and the facing surface 82. Is formed.

In this state, the molding die 9 is heated, and molten resin such as PBT is injected from the runner (step S105). The resin is filled inside the rotor core 20 inserted into the rotor

core insertion portions

73 and 83, inside the magnet insertion hole 21, and inside the core hole 26. The resin is also filled in the space inside the

tubular portions

74, 84, and further in the gap between the facing surfaces 72, 82 and the rotor core 20.

After that, the molding die 9 is cooled. As a result, the resin in the molding die 9 is cured and the resin portion 3 is formed. That is, the shaft 11, the rotor core 20, and the sensor magnet 4 are integrated by the resin portion 3 to form the rotor 2.

Specifically, the resin cured between the

tubular portions

74 and 84 of the molding die 9 and the shaft 11 becomes the inner ring portion 31 (FIG. 5). The resin cured on the inner peripheral side of the rotor core 20 (where the

cavity forming portions

76 and 86 are not arranged) becomes the inner ring portion 31, the rib 32, and the outer ring portion 33 (FIG. 5 ). The portions corresponding to the

cavity forming portions

76 and 86 of the molding die 9 are the cavities 35 (FIG. 5). The resin cured between the facing surfaces 72 and 82 of the molding die 9 and the rotor core 20 becomes the end surface portions 38 and 39 (FIG. 4).

After that, the movable mold 8 is raised and the rotor 2 is taken out from the fixed mold 7. At this time, the pin 77 of the molding die 9 comes out of the core hole 26 of the rotor core 20, and the holding portion 78 comes out of the resin portion 3. Therefore, the hollow portion 36 is formed in the portion of the resin portion 3 where the holding portion 78 was located. Further, a resin hole portion 37 (FIG. 7) is formed in a portion of the end surface portion 38 where the pin 77 was located.

On the other hand, the stator core 51 is formed by laminating electromagnetic steel plates and fixing them by caulking or the like. The stator 5 is obtained by attaching the insulating portion 52 to the stator core 51 and winding the coil 53. Further, the substrate 6 to which the lead wire 61 is attached is attached to the stator 5. Specifically, the substrate 6 is fixed to the stator 5 by inserting a protrusion provided on the resin portion 3 of the stator 5 into a mounting hole of the substrate 6 and performing heat welding or ultrasonic welding.

Then, the stator 5 to which the substrate 6 is fixed is placed in a molding die, and a resin (mold resin) such as BMC is injected and heated to form the mold resin portion 55. As a result, the mold stator 50 is completed.

After that, the

bearings

12 and 13 are attached to the shaft 11 of the rotor 2 and inserted into the hollow portion 56 from the opening 55b of the mold stator 50. Next, the bracket 15 is attached to the opening 55b of the mold stator 50. Further, the cap 14 is attached to the outside of the bracket 15. Thereby, the electric motor 1 is completed.

As described above, the shaft 11, the rotor core 20, the main magnet 25, and the sensor magnet 4 are integrally molded with resin, so that the rotor 2 is manufactured as compared with the case where the rotor 2 is configured by assembling the components. The process becomes simple.

Further, in the method of mounting the pedestal on the rotor core 20 and holding the sensor magnet 4, when the axial dimension (that is, the laminated thickness) of the rotor core 20 changes due to the tolerance, the sensor magnet 4 and the Hall element on the substrate 6 are changed. The distance between and also changes. In the first embodiment, since the sensor magnet 4 is held by the holding portion 78 of the pin 77 provided on the molding die 9, the distance between the sensor magnet 4 and the Hall element on the substrate 6 can be maintained with high accuracy. Therefore, the detection accuracy of the magnetic flux by the Hall element is improved, and the rotation accuracy and the quietness of the electric motor 1 are improved.

Further, since the protruding portion 79 provided on the holding portion 78 of the pin 77 comes into contact with the sensor magnet 4 from the inside in the radial direction, a high positional accuracy in the radial direction of the sensor magnet 4 can be obtained.

Further, since the pin 77 engages with the core hole 26 of the rotor core 20 and the holding portion 78 provided at the tip of the pin 77 holds the sensor magnet 4, the pin 77 is used to fix the rotor core 20. Both positioning and holding of the sensor magnet 4 can be performed.

The main magnet 25 may be magnetized after the rotor 2 is completed or the electric motor 1 is completed. When the main magnet 25 is magnetized after the rotor 2 is completed, a magnetizing device is used. When the main magnet 25 is magnetized after completion of the electric motor 1, a magnetizing current is passed through the coil 53 of the stator 5. In this specification, even a main magnet (that is, a magnetic body) before being magnetized is referred to as a main magnet.

In the example shown in FIG. 9, the positioning pin 77 is provided on the fixed mold 7, but it may be provided on the movable mold 8. In any case, the rotor core 20 can be positioned with respect to the molding die 9.

<Effects of the embodiment>
As described above, in the rotor 2 of the first embodiment, the resin portion 3 has the hollow portion 36 in which a part of the sensor magnet 4 is exposed. Therefore, the rotor core 20 to which the main magnet 25 is attached and the shaft 11 are arranged in the molding die 9 and integrally molded with the pin 77 provided in the molding die 9 holding the sensor magnet 4. , The rotor 2 can be manufactured.

Since it is not necessary to provide a pedestal for holding the sensor magnet 4 on the rotor 2, the number of parts of the rotor 2 can be reduced, and the step of assembling the pedestal to the rotor core 20 is also unnecessary. Therefore, the manufacturing cost can be reduced.

In addition, since the position of the sensor magnet 4 is determined by the pin 77 and the holding portion 78 thereof, even if the laminated thickness (that is, the axial dimension) of the rotor core 20 varies due to the tolerance, the sensor magnet 4 is placed on the substrate 6. It can be accurately positioned relative to it. Therefore, the detection accuracy of the magnetic flux by the Hall element of the substrate 6 is improved, and the rotation accuracy and the quietness of the electric motor 1 can be improved.

Further, since the hollow portion 36 is formed inside or outside the sensor magnet 4 in the radial direction, the sensor magnet 4 can be positioned and held from the inside or outside in the radial direction. Thereby, the accuracy of the mounting position of the sensor magnet 4 in the radial direction can be improved.

Further, since the interposition portion 39a of the resin portion 3 is interposed between the rotor core 20 and the sensor magnet 4, the influence of the main magnet 25 on the magnetic flux of the sensor magnet 4 is suppressed, and the magnetic flux detection accuracy is improved. can do. As a result, the rotation accuracy and quietness of the electric motor 1 can be improved.

Also, since the rotor 2 is of the consequent pole type, the number of main magnets can be reduced to half of that of the non-consequent pole type rotor, and the manufacturing cost can be reduced. Further, since the core hole 26 of the rotor core 20 plays a role of adjusting the flow of the magnetic flux, it is possible to suppress the disturbance of the magnetic flux and thereby suppress the vibration and noise of the electric motor 1.

Further, since the rotor core 20 is provided with a distance from the shaft 11 and the resin portion 3 connects the shaft 11 and the rotor core 20, the weight of the rotor 2 can be reduced. Further, it is possible to reduce the magnetic flux leakage from the rotor core 20 to the shaft 11 and improve the motor efficiency. Further, since the rotor core 20 and the shaft 11 are electromagnetically insulated from each other, it is possible to suppress the occurrence of electrolytic corrosion due to the axial current, and to suppress the vibration and noise of the electric motor 1 due to this.

In addition, the resin portion 3 includes an inner ring portion 31 that contacts the outer circumference of the shaft 11, an outer ring portion 33 that contacts the inner circumference 20 b of the rotor core 20, and a rib 32 that connects the inner ring portion 31 and the outer ring portion 33. Since it has, the amount of material forming the resin portion 3 can be reduced, and the manufacturing cost can be reduced. Further, since the resonance frequency of the rotor core 20 can be adjusted by the size of the rib 32, it is possible to suppress vibration and noise in, for example, a blower.

Further, since the rotor core 20 has the core hole 26 at a position facing the cavity 36, the pin 77 of the molding die 9 can be engaged with the core hole 26 to position the rotor core 20. Further, the sensor magnet 4 can be positioned by the holding portion 78 provided on the pin 77 penetrating the core hole 26.

In addition, since the core hole 26 is located inside the pole center of the first magnetic pole P1 or the second magnetic pole P2 in the circumferential direction, the flow of the magnetic flux in the rotor core 20 can be adjusted, whereby the magnetic force Unbalance can be suppressed and vibration and noise can be suppressed.

Further, since the plurality of core holes 26 of the rotor core 20 are equidistant from the central axis C1 and have the same relative positions with respect to the magnetic poles closest to each of them, the molding die 9 is used in the circumferential direction of the rotor core 20. Even if the position is changed, the core hole 26 and the pin 77 can be engaged with each other.

Further, in the manufacturing process of the rotor 2, since the shaft 11 and the rotor core 20 are integrally molded with resin, the press-fitting process of the shaft 11 and the like are unnecessary, and the manufacturing process of the rotor 2 can be simplified. ..

Modified example.
FIG. 13 is a cross-sectional view showing a rotor 2A of a modified example of the first embodiment, which corresponds to a cross-sectional view taken along line 5-5 shown in FIG. The rotor 2A of this modified example is a non-consistent pole type rotor in which all magnetic poles are composed of the main magnet 25, that is, a normal pole type rotor.

As shown in FIG. 13, the rotor 2A includes a shaft 11, a rotor core 20 provided at a distance radially outward from the shaft 11, and a plurality of main magnets embedded in the rotor core 20. 25, a sensor magnet 4 (FIG. 4) arranged on one side in the axial direction with respect to the main magnet 25, and a resin portion 3 provided between the shaft 11 and the rotor core 20. The configurations of the shaft 11, the resin portion 3, and the sensor magnet 4 are as described in the first embodiment.

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 the same distance from the central axis C1. The number of magnet insertion holes 21 is ten here. One main magnet 25 is inserted into each magnet insertion hole 21, so that the number of main magnets 25 is ten. The shape and material of the main magnet 25 are as described in the first embodiment.

The main magnets 25 adjacent to each other in the circumferential direction have magnetic poles opposite to each other on the outer peripheral side of the rotor core 20. For example, the main magnet 25 having the N pole on the outer peripheral side constitutes the first magnetic pole P1, and the main magnet 25 having the S pole on the outer peripheral side constitutes the second magnetic pole P2. That is, all the magnetic poles P1 and P2 of the rotor 2A are composed of the main magnet 25, and the number of poles is 10.

The number of poles of the rotor 2 is 10 here, but the number of poles may be an even number of 4 or more. Although one main magnet 25 is arranged in one magnet insertion hole 21 here, two or more main magnets 25 may be arranged in one magnet insertion hole 21.

Among the 10 magnet insertion holes 21 of the rotor core 20, core holes 26 are formed inside the 5 magnet insertion holes 21 in the radial direction. The pins 77 (FIG. 9) of the molding die 9 are inserted into these core holes 26 as described in the first embodiment. A holding portion 78 is provided at the tip of the pin 77 to hold the sensor magnet 4 (FIG. 9). The resin portion 3 having the hollow portion 36 (FIG. 4) is as described in the first embodiment.

The number of core holes 26 is arbitrary, but in order to hold the sensor magnet 4 in a stable posture, two or more are desirable, and three or more are more desirable. Further, the core holes 26 may be provided on the radially inner side of all the magnet insertion holes 21. In FIG. 13, the outer periphery 20a of the rotor core 20 has a circular shape, but it may have the flower circle shape described in the first embodiment.

The rotor 2A of the modified example is the same as the rotor 2 of the first embodiment except that all magnetic poles are composed of the main magnets 25. Therefore, the rotor core 20 to which the main magnet 25 is attached and the shaft 11 are arranged in the molding die 9 and integrally molded with the pin 77 provided in the molding die 9 holding the sensor magnet 4. , The rotor 2A can be manufactured. Therefore, the same effect as that of the first embodiment can be obtained.

<Air conditioner>
Next, an air conditioner to which the electric motor according to the first embodiment or its modification described above is applied will be described. FIG. 14A is a diagram showing a configuration of an air conditioner 500 to which the electric motor 1 according to the first embodiment is applied. The air conditioner 500 includes an outdoor unit 501, an indoor unit 502, and a refrigerant pipe 503 connecting these units.

The outdoor unit 501 includes an outdoor blower 510 such as a propeller fan, and the indoor unit 502 includes an indoor blower 520 such as a cross flow fan. The outdoor blower 510 includes an impeller 505 and the electric motor 1 that drives the impeller 505. The indoor blower 520 includes an impeller 521 and the electric motor 1 that drives the impeller 521. Each of the electric motors 1 has the configuration described in the first embodiment. A compressor 504 that compresses the refrigerant is also shown in FIG.

FIG. 14B is a cross-sectional view of the outdoor unit 501. The electric motor 1 is supported by a frame 509 arranged inside a housing 508 of the outdoor unit 501. An impeller 505 is attached to the shaft 11 of the electric motor 1 via a hub 506.

In the outdoor blower 510, the impeller 505 is rotated by the rotation of the rotor 2 of the electric motor 1 to blow the air to the outside. 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 (not shown) is released to the outside by the blower of the outdoor blower 510.

Similarly, in the indoor blower 520 (FIG. 14(A)), the rotation of the rotor 2 of the electric motor 1 causes the impeller 521 to rotate and blows the air indoors. During the cooling operation of the air conditioner 500, the air from which heat is removed when the refrigerant evaporates in the evaporator (not shown) is blown indoors by the blower 520.

The electric motor 1 of the first embodiment described above has a high electric motor efficiency due to the suppression of magnetic flux leakage, so that the operating efficiency of the air conditioner 500 can be improved. Further, since the resonance frequency of the electric motor 1 can be adjusted, the resonance between the electric motor 1 and the impeller 505 (521), the resonance of the entire outdoor unit 501, and the resonance of the entire indoor unit 502 can be suppressed, and noise is reduced. It can be reduced.

Note that the rotor 2A (FIG. 13) of the modified example may be used for the electric motor 1. Although the electric motor 1 is used as the drive source of the outdoor blower 510 and the drive source of the indoor blower 520 here, the electric motor 1 may be used as at least one of the drive sources.

Also, the electric motor 1 described in the first embodiment and the modified example can be mounted on an electric device other than the blower of the air conditioner.

Although the preferred embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various improvements or modifications can be made without departing from the scope of the present invention. be able to.

1 electric motor, 2, 2A rotor, 3 resin part, 4 sensor magnet, 5 stator, 6 substrate, 7 fixed mold, 8 movable mold, 9 molding mold, 11 shaft, 20 rotor core, 21 magnet insertion Hole, 25 main magnet, 26 core hole, 31 inner ring part, 32 rib, 33 outer ring part, 36 hollow part, 37 resin hole part, 38, 39 end face part, 39a interposition part, 50 mold stator, 51 stator Core, 52 insulating part, 53 coil, 55 mold resin part, 70 contact part, 71 shaft insertion hole, 72 facing surface, 73 rotor core insertion part, 74 tubular part, 75 mold matching surface, 76 cavity forming part , 77 pin (projection part), 78 holding part, 81 shaft insertion hole, 82 facing surface, 83 rotor core insertion part, 84 cylindrical part, 85 mold matching surface, 86 cavity forming part, 501 outdoor unit, 502 indoor Machine, 503 refrigerant pipe, 505 impeller, 510 outdoor blower, 520 indoor blower, 521 impeller.

Claims

Shaft,
An annular rotor core that surrounds the shaft from the outside in the radial direction around the central axis of the shaft,
A main magnet attached to the rotor core;
A sensor magnet arranged on one side of the main magnet in the direction of the central axis;
A resin portion that is provided on the rotor core and holds the sensor magnet,
The resin part has a hollow part where a part of the sensor magnet is exposed.
The rotor according to claim 1, wherein the hollow portion is formed inside or outside in a radial direction centered on the central axis of the sensor magnet.
The rotor according to claim 1 or 2, wherein the resin portion has an interposition portion located between the rotor core and the sensor magnet.
The rotor according to any one of claims 1 to 3, wherein the sensor magnet has a ring shape surrounding the central axis.
The main magnet constitutes the first magnetic pole,
The rotor according to any one of claims 1 to 4, wherein a part of the rotor core constitutes a second magnetic pole.
The main magnet constitutes the first magnetic pole,
The rotor according to any one of claims 1 to 4, wherein another main magnet adjacent to the main magnet constitutes a second magnetic pole.
The rotor core is provided at a distance from the shaft,
The rotor according to any one of claims 1 to 6, wherein the resin portion connects the shaft and the rotor core.
The said resin part has an inner ring part which contacts the outer periphery of the said shaft, the outer ring part which contacts the inner periphery of the said rotor core, and the rib which connects the said inner ring part and the said outer ring part. The rotor described in.
The rotor according to any one of claims 1 to 8, wherein the rotor core has a core hole at a position corresponding to the hollow portion.
The rotor has a plurality of magnetic poles in a circumferential direction around the central axis,
The rotor core has a plurality of core holes equidistant from the central axis,
The rotor according to any one of claims 1 to 8, wherein the plurality of core holes have the same relative positions with respect to the closest magnetic poles.
The resin portion has an end surface portion that covers at least a part of the end surface of the rotor core in the direction of the central axis,
The rotor according to claim 10, wherein the end surface portion has a number of hole portions equal to or less than the number of the plurality of core holes.
A rotor according to any one of claims 1 to 11,
A stator surrounding the rotor from the outside in the radial direction.
An electric motor according to claim 12;
An impeller rotated by the electric motor.
An outdoor unit, an indoor unit, and a refrigerant pipe connecting the outdoor unit and the indoor unit,
At least one of the outdoor unit and the indoor unit,
An air conditioner including the blower according to claim 13.
A step of preparing an annular rotor core to which a main magnet is attached and a shaft,
The shaft and the rotor core are arranged in a molding die, and a jig provided on the molding die holds a sensor magnet on one side in the direction of the central axis of the shaft of the rotor core, A step of integrally molding the shaft, the rotor core, the main magnet, and the sensor magnet with a resin.
The method of manufacturing a rotor according to claim 15, wherein the jig penetrates a core hole provided in the rotor core, and the sensor magnet is held by a tip portion of the jig.