WO2007132768A1

WO2007132768A1 - Motor

Info

Publication number: WO2007132768A1
Application number: PCT/JP2007/059742
Authority: WO
Inventors: Hu Li; Yuichi Yoshikawa; Hiroshi Murakami
Original assignee: Panasonic Corporation
Priority date: 2006-05-17
Filing date: 2007-05-11
Publication date: 2007-11-22
Also published as: JP4569632B2; JPWO2007132768A1

Abstract

A motor comprises a stator including a stator core having an annular stator yoke and inner and outer teeth projecting from the stator yoke to the inner and outer sides, and coils wound around the stator core; and an inner rotor and an outer rotor facing the inner and outer teeth with spaces therebetween and having permanent magnets. The amplitudes of the waveforms of the cogging torques by the inner and outer rotors are made equal to each other by adjusting the amounts of the magnetic flux produced from the inner and outer rotors.

Description

Specification

motor

Technical field

The present invention relates to a motor in which two rotors, an inner rotor and an outer rotor, are mounted and a toroidal winding is applied to a stator.

Background art

[0002] A brushless motor used for a drive motor of a direct drive washing machine or the like is desired to have low speed, large torque, low vibration, and low noise. Since the motor used in direct drive is driven directly without gears, it is necessary to increase the torque of the motor.Therefore, the rotor side has an inner rotor and an outer rotor, and the stator side has an inner diameter side and an outer rotor. A double rotor type brushless motor with teeth on the diameter side has been proposed.

[0003] Patent Document 1 discloses such a double rotor type brushless motor technology. In such a double rotor type brushless motor, torque is generated in the inner rotor and the outer rotor due to the current flowing in the winding arranged in the inner slot portion and the outer slot portion. For this reason, compared with the motor of the same volume provided only with an inner side rotor or only an outer side rotor, a big torque can be output and it can be made highly efficient. However, in such a double rotor type motor, the cogging torque and torque ripple due to the inner rotor and the cogging torque and torque ripple due to the outer rotor are combined to generate a larger cogging torque and torque ripple. Happened.

[0004] For this reason, Patent Document 1 proposes a configuration in which the position of the boundary between the magnetic poles of the inner rotor and the outer rotor is shifted by an arbitrary angle. Also, by changing the combination of the slot opening width of the inner teeth and the slot opening width of the outer teeth, the phase of the cogging torque waveform by the inner rotor and the phase of the cogging torque waveform by the outer rotor are reversed. Technology has also been proposed. As described above, the cogging torque by the inner rotor and the cogging torque by the outer rotor can be canceled out to reduce the cogging torque of the motor as a whole! /

[0005] FIG. 10 shows the rotor rotation position (electrical angle) and cogging torque of a conventional double rotor type motor. It is a graph which shows the relationship. In Fig. 10, the broken line shows the cogging torque by the inner rotor, the thin solid line shows the cogging torque by the outer rotor, and the thick solid line at the center shows the cogging torque of the entire motor.

[0006] As described above, even if the inner rotor and the outer rotor are configured to cancel the phase of the cogging torque of the inner rotor and the phase of the cogging torque of the outer rotor, the cogging of the outer rotor is larger than the cogging torque of the inner rotor. Since the torque is larger, it is difficult to completely cancel the torque.

Patent Document 1: Japanese Patent Laid-Open No. 2001-037133

Disclosure of the invention

[0007] The motor of the present invention has the following configuration. An annular stator yoke, a plurality of inner teeth projecting radially inward in the stator yoke force, a plurality of outer teeth projecting in the same number as the inner teeth, and the stator yoke also projecting radially outward, and an inner side A stator core having an inner slot configured between the teeth and an outer slot configured between the outer teeth, and a stator yoke between the inner slot and the outer slot, wound in a three-phase star or delta shape And a stator having a plurality of connected coils.

[0008] An inner rotor opposed to the inner teeth via a gap, and an outer rotor connected to the same rotation shaft as the inner rotor and opposed to the outer teeth via the gap, the inner rotor having a predetermined shape The outer rotor has an inner rotor yoke laminated with punched electromagnetic steel sheets and an inner permanent magnet, and the outer rotor has an outer rotor yoke laminated with electromagnetic steel sheets punched into a predetermined shape and the outer permanent yoke having the same number of poles as the inner permanent magnet. And a magnet.

[0009] Here, by adjusting the amount of magnetic flux generated from the inner rotor and the amount of magnetic flux generated from the outer rotor, the amplitude of the cogging torque waveform by the inner rotor and the amplitude of the cogging torque waveform by the outer rotor are obtained. The configuration is the same.

With this configuration, the motor of the present invention has good volumetric efficiency, and when high output and high torque are obtained, the torque of the cogging torque is reduced while taking advantage of the characteristics of the double rotor type brushless motor. Low vibration and low noise motor can be realized.

Brief Description of Drawings

FIG. 1 is an external perspective view of a motor according to Embodiment 1 of the present invention. 2] FIG. 2 is an exploded perspective view of the motor according to Embodiment 1 of the present invention.

3] FIG. 3 is an exploded perspective view of the motor according to Embodiment 1 of the present invention.

FIG. 4 is a cross-sectional view of the motor according to Embodiment 1 of the present invention.

FIG. 5 is a cross-sectional view of a main part of the motor according to Embodiment 1 of the present invention.

FIG. 6 is a graph showing the relationship between the rotor rotational position (electrical angle) and the cogging torque of the motor according to Embodiment 1 of the present invention.

FIG. 7 is a longitudinal sectional view of an essential part of a motor according to Embodiment 2 of the present invention.

FIG. 8 is a longitudinal sectional view of a main part of a motor according to Embodiment 3 of the present invention.

FIG. 9 is a longitudinal sectional view of a main part of a motor according to Embodiment 4 of the present invention.

FIG. 10 is a graph showing the relationship between the rotor rotational position (electrical angle) and the cogging torque in a conventional motor.

Explanation of symbols

4 Rotating axis

10 Stator

11 Stator core

12 Outer teeth

13 Inner teeth

14 Stator yoke

15 Koinole

16 Outer slot

17 Inner slot j slot

20, 120, 220, 320 Inner rotor

21, 121, 221, 321 Inner side j Rotor yoke

22, 122, 222, 322 Inner permanent magnet

23 Inner permanent magnet hole

30, 130, 230, 330 Outer rotor

31, 131, 231, 331 Outer rotor yoke

32, 132, 232, 332 outer permanent magnet 33 Outer permanent magnet hole

50, 51 Molded resin

60 Mounting part

62 Ribs

64 Vent

65 Convex

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] (Embodiment 1)

FIG. 1 is a perspective view of a motor according to Embodiment 1 of the present invention. 2 and 3 are exploded perspective views of the motor according to Embodiment 1 of the present invention. FIG. 4 is a cross-sectional view of the motor according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view of an essential part showing a 5-5 cross section of FIG.

In these drawings, the motor of the present invention has a stator 10, an inner rotor 20 that is opposed to the inner diameter side of the stator 10 with a predetermined gap, and a predetermined gear on the outer diameter side of the stator 10. It has an outer rotor 30 that is opposed to it. The inner rotor 20 and the outer rotor 30 are integrally formed with a mold resin 50 and transmit torque to the outside through the rotating shaft 4. On the other hand, the stator 10 is also almost entirely covered with the mold resin 51, and the outer periphery of the stator 10 is integrally formed with the mold resin 51 in a uniform interval pitch or a non-uniform interval pitch in the rotation direction. A mounting portion 60 is formed. A sensor for detecting the rotational position of the outer port 30 is disposed between the adjacent mounting portions 60. For this reason, the mounting portion 60 is formed at a position that avoids the sensor position.

A plurality of air holes 64 penetrating in the direction of the rotating shaft 4 are formed in the mold resin 50 that integrally connects the inner rotor 20 and the outer rotor 30. Further, a convex portion 65 is provided at a portion of the mold resin 50 that integrally connects the inner rotor 20 and the outer rotor 30 so as to face the stator 10 in the axial direction. Thereby, when the inner rotor 20 and the outer rotor 30 rotate, the heat generated from the stator 10 is agitated. Then, hot air in the rotational direction is generated between the stator 10, the inner rotor 20 and the outer rotor 30. This hot wind wind vent 64 from outside the motor Is released to the part. A plurality of ribs 62 are provided on the back side of the mold resin 50 that integrally connects the inner rotor 20 and the outer rotor 30. Thereby, the required intensity | strength can be ensured, reducing mold fat amount.

The stator 10 includes a substantially annular stator yoke 14, an outer tooth 12 projecting from the stator yoke 14 in the outer circumferential direction, and an inner tooth 13 projecting from the stator yoke 14 in the inner circumferential direction in the same number as the outer teeth 12. It consists of. Between each outer tooth 12, an outer slot 16 force An inner slot 17 is formed between each inner tooth 13. A plurality of coils 15 force by a toroidal winding system connected in a three-phase star or delta shape is wound around the stator yoke 14 between the outer slot 16 and the inner slot 17 by a concentrated winding system.

[0018] As described above, the stator 10 is integrally formed from a mold resin 51 after winding the coil 15. This is for fixing the coil 15 to the stator core 11 and for preventing moisture and preventing moisture. In particular, when this motor is used in a washing machine, it is expected to have moisture-proofing and anti-plucking effects. Both the mold resin 50 and the mold resin 51 are preferably unsaturated polyester resins containing fillers. This is because the fluidity during molding and the strength after molding are excellent.

Next, the configuration on the rotor side will be described. An outer rotor 30 is disposed opposite to the outer teeth 12 of the stator 10 via a predetermined gap. Similarly, the inner rotor 20 is disposed so as to face the inner teeth 13 through a predetermined gap.

[0020] The outer rotor 30 includes an outer rotor yoke 31 and a plurality of outer permanent magnets 32 embedded in a plurality of outer permanent magnet embedding holes 33 formed in the outer rotor yoke 31. The outer rotor yoke 31 is formed by laminating electromagnetic steel plates punched into a predetermined shape (ring shape having the outer permanent magnet embedding hole 33) to constitute a magnetic circuit. Similarly, the inner rotor 20 includes an inner rotor yoke 21 and a plurality of inner permanent magnets 22 embedded in a plurality of inner permanent magnet embedding holes 23 formed in the inner rotor yoke 21. The inner rotor yoke 21 is laminated with electromagnetic steel plates punched into a predetermined shape (ring shape having an inner permanent magnet embedding hole 23), and constitutes a magnetic circuit.

[0021] It should be noted that the outer rotor 30 and the inner rotor 20 each have no rotor frame. Yes. Therefore, the weight can be reduced and the number of manufacturing steps can be reduced. Furthermore, the volume of the rotor frame can be covered with the mold resin 50 to absorb vibrations.

[0022] The outer rotor 30 and the inner rotor 20 are inserted into a resin molding die and integrally molded by a mold resin 50. Then, the outer rotor 30 and the inner rotor 20 are rotated together by being connected to the rotating shaft 4 and applying a predetermined current to the coil 15. By adopting an integral configuration of the outer rotor 30 and the inner rotor 20 as described above, the motor in this embodiment has a higher torque than a general inner rotor motor or outer rotor motor. High output can be realized.

Here, in the motor according to this embodiment, the number of poles of the inner rotor 20 and the number of poles of the outer rotor 30 are both 12, and the number of slots is 18 slots. Thus, by using a combination of 12 poles and 18 slots, the winding arrangement can achieve the same effect as distributed winding.

FIG. 6 is a graph showing the relationship between the rotor rotational position (electrical angle) and the cogging torque of the double rotor type motor according to the present embodiment. In FIG. 6, the broken line indicates the cogging torque due to the inner rotor 20, the thin solid line indicates the cogging torque due to the outer rotor 30, and the thick solid line at the center indicates the cogging torque of the entire motor combining these.

In the motor according to the first embodiment, the inner rotor 20 and the outer rotor 30 are configured to cancel the phase of the cogging torque of the inner rotor 20 and the phase of the cogging torque of the outer rotor 30. . However, since the cogging torque of the outer rotor 30 is larger than the cogging torque of the inner rotor 20, it is difficult to completely cancel out. As a countermeasure against this, in the present embodiment, the axial length of the inner permanent magnet 22 is made longer than the axial length of the outer permanent magnet 32 as shown in FIG. This is due to the following reason.

[0026] When the length of the circumference where the inner permanent magnet 22 is arranged is compared with the length of the circumference where the outer permanent magnet 32 is arranged, the circumference length where the inner permanent magnet 22 is arranged is equal to the outer permanent magnet. It is shorter than the circumference of 32. For this reason, the length of the inner permanent magnet 22 in the rotational direction is shorter than the dimension of the outer permanent magnet 32 in the rotational direction. Therefore, if the axial length of the inner permanent magnet 22 and the axial length of the outer permanent magnet 32 are the same, the inner rotor The amount of magnetic flux generated from 20 and the amount of magnetic flux generated from the outer rotor 30 are different. If so, the amplitude of the cogging torque waveform by the inner rotor 20 and the amplitude of the cogging torque waveform by the outer rotor 30 are different, and the cogging torque of the entire motor cannot be completely canceled.

[0027] From the above, in the present embodiment, the axial length of the inner permanent magnet 22 is made longer than the axial length of the outer permanent magnet 32, and at the same time, the inner rotor yoke 21 is made thicker than the outer permanent magnet 22. It is thicker than the rotor yoke 31. Thus, the amount of magnetic flux generated from the inner rotor 20 and the amount of magnetic flux generated from the outer rotor 30 are adjusted. In this way, the amplitude of the waveform of the cogging torque of the inner rotor 20 and the amplitude of the waveform of the cogging torque of the outer rotor 30 are made substantially the same. With such a configuration, as shown in FIG. 6, the cogging torque of the inner rotor 20 and the cogging torque of the outer rotor 30 can be canceled, and the cogging torque of the entire motor can be greatly reduced.

[0028] In the present embodiment, the force showing the configuration of 12 poles and 18 slots The present invention can be applied to other configurations such as a configuration of 30 poles and 18 slots. However, if the number of poles is less than 12, there is a problem that the torque output is reduced. On the other hand, if the number of poles is greater than 30, there is a problem that iron loss increases.

[0029] Further, the force showing a configuration in which the permanent magnet is embedded in the rotor yoke. The present invention can also be applied to a configuration in which the permanent magnet is attached to the surface of the rotor yoke. Alternatively, either one of the inner rotor 20 and the outer rotor 30 may be configured to embed a permanent magnet in the rotor yoke, and the other may be configured to attach the permanent magnet to the rotor yoke surface.

[0030] (Embodiment 2)

FIG. 7 is a cross-sectional view of a main part of the motor according to Embodiment 2 of the present invention. The same constituent elements as those in the first embodiment are given the same reference numerals and the description thereof is omitted.

[0031] The motor according to the second embodiment includes the axial length of the inner permanent magnet 122 and the axial length of the outer permanent magnet 132, and the stack thickness of the inner rotor yoke 121 and the stack thickness of the outer rotor yoke 1 31. Are the same. On the other hand, the radial thickness of the inner permanent magnet 122 is made larger than the radial thickness of the outer permanent magnet 132. Other configurations are the same as those in the first embodiment. The motor according to the second embodiment adjusts the amount of magnetic flux generated from the inner rotor 120 and the amount of magnetic flux generated from the outer rotor 130 by the configuration as described above. As in the first embodiment, the amplitude of the waveform of the cogging torque of the inner rotor 120 and the amplitude of the waveform of the cogging torque of the outer rotor 130 are substantially the same. Thereby, as shown in FIG. 6, the cogging torque of the inner rotor 120 and the cogging torque of the outer rotor 130 can be canceled, and the cogging torque of the entire motor can be greatly reduced.

[0033] In the present embodiment, the force described as the axial length of the inner permanent magnet 122 and the axial length of the outer permanent magnet 132 are not necessarily the same. Similarly, although it has been described that the inner rotor yoke 121 and the outer rotor yoke 131 have the same thickness, they need not necessarily be the same. With the essential condition that the radial thickness of the inner permanent magnet 122 is larger than the radial thickness of the outer permanent magnet 132, the axial length of the permanent magnet and the stack thickness of the rotor yoke can be changed as appropriate.

[Embodiment 3]

FIG. 8 is a cross-sectional view of a main part of the motor according to Embodiment 3 of the present invention. The same constituent elements as those in the first embodiment are given the same reference numerals and the description thereof is omitted.

In the motor according to the third embodiment, the inner rotor yoke 221 and the outer rotor yoke 231 have substantially the same thickness, and the axial length of the inner permanent magnet 222 is set to the axial direction of the outer permanent magnet 232. It is longer than the length of. The rest is the same as in the first embodiment.

The motor according to the present embodiment adjusts the amount of magnetic flux generated from inner rotor 220 and the amount of magnetic flux generated from outer rotor 230 by the configuration as described above. As a result, similarly to the first embodiment, the amplitude of the waveform of the cogging torque of the inner rotor 220 and the amplitude of the waveform of the cogging torque of the outer rotor 230 are made substantially the same. Therefore, as shown in FIG. 6, the cogging torque of the inner rotor 220 and the cogging torque of the outer rotor 230 can be canceled, and the cogging torque of the entire motor can be greatly reduced.

[0037] (Embodiment 4)

FIG. 9 is a cross-sectional view of main parts of a motor according to Embodiment 4 of the present invention. The same constituent elements as those in the first embodiment are given the same reference numerals and the description thereof is omitted.

[0038] The motor according to the present embodiment includes the axial length of inner permanent magnet 322 and the outer permanent magnet. The axial length of 332, and the thickness of the inner rotor yoke 321 and the thickness of the outer rotor yoke 331 are both substantially the same. On the other hand, the inner permanent magnet 322 and the outer permanent magnet 332 are made of different materials, and the residual magnetic flux density of the inner permanent magnet 322 is made larger than the residual magnetic flux density of the outer permanent magnet 332. The rest is the same as in the first embodiment.

Specifically, as an example, neodymium 'iron-boron-based sintered magnet (Br = l.36T) is used as the inner permanent magnet 322, and ferrite-based sintered magnet (Br = 0. 44T) is used. Thereby, the amount of magnetic flux generated from the inner rotor 320 and the amount of magnetic flux generated also by the outer rotor 330 force can be adjusted. As in the first embodiment, the amplitude of the cogging torque waveform of the inner rotor and the amplitude of the cogging torque waveform of the outer rotor are substantially the same. Thereby, as shown in FIG. 6, the cogging torque of the inner rotor 320 and the cogging torque of the outer rotor 330 can be canceled, and the cogging torque of the entire motor can be greatly reduced.

In the present embodiment, the axial length of the inner permanent magnet 322 and the axial length of the outer permanent magnet 332 have been described as being substantially the same, but are not limited to the same. . Similarly, the inner rotor yoke 321 and the outer rotor yoke 331 are described as having substantially the same thickness, but are not limited to the same. As an essential requirement that the residual magnetic flux density of the inner permanent magnet 322 be larger than the residual magnetic flux density of the outer permanent magnet 332, the axial length of the permanent magnet and the stack thickness of the rotor yoke may be appropriately changed.

[0041] Although the material of the permanent magnet has been described as a different material, it is not limited to a different material. For example, the inner permanent magnet 322 and the outer permanent magnet 332 are made of the same neodymium / iron / boron sintered magnet, and the residual magnetic flux density of the inner permanent magnet 322 is changed to the outer permanent magnet by changing the blending method. It can also be made larger than the residual magnetic flux density of the magnet 332.

Industrial applicability

[0042] The present invention is useful for motors that are small and have limited space, such as home appliances and electrical equipment, and that require high output, high efficiency, low vibration, low noise, and low cost.

Claims

The scope of the claims

[1] An annular stator yoke, a plurality of inner teeth projecting radially inward from the stator yoke, and the same number of inner teeth projecting outward from the stator yoke force radially outward A stator core having a plurality of outer teeth, an inner slot formed between the inner teeth, and an outer slot formed between the outer teeth, and the stator yoke between the inner slot and the outer slot A stator having a plurality of coils wound around and connected in a three-phase star or delta shape;

An inner rotor opposed to the inner teeth via a gap, and an outer rotor connected to the same rotation shaft as the inner rotor and opposed to the outer teeth via a gap, the inner rotor having a predetermined shape It has an inner rotor with laminated punched electrical steel sheets and an inner permanent magnet,

The outer rotor has an outer rotor in which electromagnetic steel plates punched into a predetermined shape are stacked, and an outer permanent magnet having the same number of poles as the inner permanent magnet,

By adjusting the amount of magnetic flux generated from the inner rotor and the amount of magnetic flux generated by the outer rotor force, the amplitude of the cogging torque waveform by the inner rotor and the amplitude of the cogging torque waveform by the outer rotor are the same. A motor having a configuration of

[2] The motor according to claim 1, wherein the axial length of the inner permanent magnet is longer than the axial length of the outer permanent magnet.

3. The motor according to claim 1, wherein the inner rotor yoke is thicker than the outer rotor yoke.

4. The motor according to claim 1, wherein the radial thickness of the inner permanent magnet is greater than the radial thickness of the outer permanent magnet.

5. The motor according to claim 1, wherein the residual magnetic flux density of the inner permanent magnet is greater than the residual magnetic flux density of the outer permanent magnet.

[6] The inner rotor yoke has a plurality of inner permanent magnet holes, the inner permanent magnet is embedded in the inner permanent magnet hole, the outer rotor yoke has a plurality of outer permanent magnet holes, and the outer permanent magnet is The motor according to claim 1, embedded in the outer permanent magnet hole,

7. The motor according to claim 1, wherein the inner rotor and the outer rotor are integrally formed by a resin mold.

8. The motor according to claim 7, wherein the resin mold includes a plurality of air holes penetrating in the direction of the rotation axis.

9. The motor according to claim 7, wherein the resin mold includes a convex portion at a portion facing the stator in the axial direction.

[10] The motor according to claim 1, wherein the stator is covered with a mold resin and integrally includes a mounting portion.