CN112186922A

CN112186922A - External rotation type surface magnet rotating motor

Info

Publication number: CN112186922A
Application number: CN202010482781.8A
Authority: CN
Inventors: 堀雅宽; 三好努; 矢岛健司; 税所亮平
Original assignee: Hitachi Industrial Equipment Systems Co Ltd
Current assignee: Hitachi Industrial Equipment Systems Co Ltd
Priority date: 2019-07-03
Filing date: 2020-06-01
Publication date: 2021-01-05
Anticipated expiration: 2040-06-01
Also published as: CN112186922B; JP7217205B2; JP2021010284A

Abstract

The invention provides an outward turning type surface magnet rotating motor and a traction machine for an elevator, which reduce the adverse effect of magnet damage and increase of magnetic resistance and reduce torque pulsation, wherein the outward turning type surface magnet rotating motor comprises a rotor provided with a rotor iron core and a permanent magnet arranged on the inner diameter side of the rotor iron core; and a stator having a stator core disposed on the inner diameter side of the rotor with a gap therebetween and a coil attached to the stator core, wherein the rotor core has a plurality of gaps for each 1 pole on the outer diameter side of the surface on which the permanent magnet is attached.

Description

External rotation type surface magnet rotating motor

Technical Field

The present invention relates to an external rotation type surface magnet rotating electric machine.

Background

A rotating electrical machine as an electromechanical energy conversion device is built in various devices, and as the devices are miniaturized, the miniaturization of the rotating electrical machine is also demanded. As one of the methods for downsizing a rotating electric machine, an external-rotation type permanent magnet rotating electric machine is used. The external-rotation type permanent magnet rotating electrical machine has a structure in which a rotor having a permanent magnet mounted thereon is disposed on the outer peripheral side of a stator having a coil mounted thereon. The outer rotor type permanent magnet rotating electrical machine has a larger radius of a rotor-stator gap (gap) than the inner rotor type permanent magnet rotating electrical machine, and has a feature that a magnet having a large area as viewed in the radial direction can be arranged because the circumference of 1 pole is longer because the rotor is located outside. This can achieve high output and miniaturization of the rotating electric machine.

Since the rotor core of the external-rotor permanent magnet rotating electrical machine is located on the outer peripheral side of the magnet, the problem of holding the magnet against the centrifugal force is small, and therefore, the surface magnet type is frequently used. By using the surface magnet type, short-circuiting of magnetic flux in the rotor core is reduced, and therefore, the effective magnetic flux can be increased, and high output can be achieved.

As one problem of the rotating electric machine, there is a decrease in torque ripple. The torque ripple refers to the ripple of the torque. The torque ripple causes vibration and noise of the drive device.

The torque ripple reduction is disclosed in patent document 1. A rotor of a rotating electrical machine includes a substantially annular rotor core having a plurality of magnet insertion holes formed at predetermined intervals in a circumferential direction, and permanent magnets inserted into the magnet insertion holes. The rotor core is characterized in that: the rotor core is formed by laminating a large number of electromagnetic steel plates, and has a hole portion on the substantially d-axis of each magnetic pole portion formed of a permanent magnet on the outer peripheral side of a magnet insertion hole of the rotor core.

Further, there is a technique described in patent document 2 for reducing the torque ripple. The method is characterized in that: the spindle motor includes a magnet holding portion including a cylindrical multi-pole magnetized magnet and a back yoke disposed in contact with one surface of the magnet in a radial direction, and a magnetic field generating portion disposed at a position opposite to the other surface of the magnet, wherein either the magnet holding portion or the magnetic field generating portion is rotatably disposed, and the back yoke is provided with a recess along a boundary line of adjacent magnetic poles of the magnet on the surface in contact with the magnet.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2018-

Patent document 2: japanese patent laid-open No. 2001-

Disclosure of Invention

Problems to be solved by the invention

In patent document 1, a gap is provided on the gap side of the magnet to reduce torque ripple. However, in the surface magnet type, since the magnet faces the gap, it is difficult to cope with this.

In patent document 2, torque ripple is reduced by providing a groove (nonmagnetic portion) on the outer shape side of the magnet end portion. However, the non-magnetic portion increases the magnetic resistance, and therefore the magnetic flux at the end of the magnet cannot be effectively used. Further, when the magnet receives an impact for some reason, the magnet is less likely to be damaged because of the fewer components for holding the magnet.

The invention aims to provide an outward turning type surface magnet rotating motor which reduces the adverse effects of magnet breakage and increase of magnetic resistance and reduces torque pulsation.

Means for solving the problems

A preferred example of the present invention is an outward turning type surface magnet rotating electrical machine comprising: a rotor having a rotor core and a permanent magnet disposed on an inner diameter side of the rotor core; and a stator including a stator core disposed on an inner diameter side of the rotor with a gap therebetween and a coil attached to the stator core, wherein the rotor core has a plurality of gaps for each 1 pole on an outer diameter side of a surface on which the permanent magnet is attached.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to reduce the adverse effects of magnet breakage and an increase in magnetic resistance, and to achieve a reduction in torque ripple.

Drawings

Fig. 1 is a view showing a radial cross section of an outer rotor type surface magnet rotating electrical machine according to embodiment 1.

Fig. 2 is a view showing a radial cross section of example 1 with a void enlarged.

Fig. 3 is a view showing a radial cross section of example 2 with an enlarged void.

Fig. 4 is a diagram showing torque ripple with respect to the number of gaps in example 2.

Fig. 5 is a view showing a radial cross section of example 3 with a void enlarged.

Fig. 6 is a diagram showing torque ripple with respect to the gap position in example 3.

Fig. 7 is a view showing an axial cross section in example 4.

Fig. 8 is a view showing an axial cross section of an elevator hoisting machine according to embodiment 5.

Detailed Description

Hereinafter, embodiments will be described based on the drawings.

[ example 1]

Fig. 1 shows an outer rotor type surface magnet rotating electrical machine according to embodiment 1 of the present invention. Fig. 1 is a radial sectional view of an outer rotor type surface magnet rotating electrical machine. Radial refers to the direction from the center to the periphery of fig. 1. The outer-rotor surface-magnet rotating electrical machine 1 of the present embodiment includes a rotor 4 including a rotor core 2 and a permanent magnet 3, and a stator 7 including a stator core 5 and a coil 6, which is disposed on the inner diameter side of the rotor 4 with a predetermined gap.

Here, the permanent magnet 3 is preferably of a surface magnet type disposed on the surface of the rotor core 2. By disposing the permanent magnets 3 on the surface of the rotor core 2, the leakage flux caused by short-circuiting of the magnet flux in the rotor can be reduced, and the effective flux can be increased, thereby achieving a higher output.

The coil 6 is preferably mounted to the stator core 5 by concentrated winding. This shortens the axial length of the coil 6, and shortens the axial length of the outward turning type surface magnet rotating electric machine 1, thereby achieving downsizing. Further, it is preferable that the portion (slot 8) of the stator core 5 where the coil 6 is disposed be an open slot. This facilitates insertion of the coil 6, thereby improving assemblability.

Further, the curvature radius of the vicinity of the gap side (tooth tip) of the stator core 5 is preferably smaller than the radius of the stator 7. This can reduce the rate of change in magnetic resistance in the circumferential direction, and can reduce torque ripple.

Here, a gap 9 is provided on the outer diameter side of the mounting surface of the rotor core 2 on which the permanent magnets 3 are mounted. Fig. 2 shows an enlarged view of the vicinity of the gap 9. By providing the gap, the variation in magnetic resistance when viewed from the stator side is leveled, the harmonic component overlapping with the magnetic flux is reduced, and the torque ripple can be reduced. In fig. 2, the gaps 9 are arranged so as to correspond to 2 magnets.

When the number of the gaps 9 is 1, there is a possibility that the gap may be increased in order to be located at a gap position where the optimal torque pulsation reduction can be obtained. Since the air gap 9 is a nonmagnetic portion, it is considered as a magnetic resistance from the magnet. When the number of voids becomes large, the magnetic resistance becomes large, and thus the electrical characteristics are degraded. On the other hand, when 2 or more voids are formed so as not to be in contact with each other, magnetic flux can pass through the voids due to the magnetic substance, and the deterioration of the electrical characteristics can be reduced.

Further, since the shape of the magnet arrangement portion is fixed by forming the gap without forming the recess and the groove, the manufacturing method does not need to be changed, and the risk of damage of the magnet due to impact is the same as that of the related art, so that the present configuration can be easily applied.

Although fig. 1 shows a 40-pole 48-slot outer rotor type surface magnet rotating electrical machine, the shape is not limited to this, and similar effects can be obtained with other slot combinations. In the case where the external rotation type rotating electric machine is double-rotating, it is preferable that the 2 air gap positions are symmetrical with respect to the central axis of the permanent magnet 3 as shown in fig. 2.

Further, the gap does not need to be filled with air, and may be a non-magnetic material such as resin. The shape of the gap may be a semicircular shape in fig. 2, a circular shape, a triangular shape, a trapezoidal shape, or the like, and the shape is not limited. In addition, the size and shape of the gap need not be uniform within 1 magnetic pole, and the size, shape, and position of the gap may be changed for each magnetic pole. The permanent magnets 3 may be arranged 1 or more per 1 pole, and may be arranged in the circumferential direction so as to maintain a substantially constant space with the permanent magnets of the adjacent magnetic poles.

According to embodiment 1, the gap 9 is disposed in the rotor core 2 on the outer diameter side of the mounting surface of the rotor core 2 on which the permanent magnets 3 are mounted, and the possibility of damage to the magnets can be reduced without affecting the member for holding the magnets. Further, it is possible to reduce the adverse effect of the increase in the magnetic resistance and achieve the reduction in the torque ripple.

[ example 2]

Fig. 3 is a diagram showing an external rotor type surface magnet rotating electric machine according to embodiment 2. In example 1, the number of voids per 1 pole was examined to be 2, but the number of voids may be 2 or more. Fig. 4 shows 6 torque pulses with respect to the number of gaps. The 6 torque pulses are pulses that are multiples of 6 of the fundamental frequency.

As described above, the torque ripple reduction effect differs depending on the position of the gap. Therefore, the position and size of the void are defined by the same reference by the optimization method. As can be seen from fig. 4, when the number of gaps is set to 2 to 4, the torque ripple is reduced, and the effect of reducing the torque ripple is significantly increased.

However, when the number of gaps is 4 to 6, the variation in the torque ripple reduction effect is small. When the number of processes increases when the number of voids increases, the cost may increase, and therefore, it is not preferable to increase the number of processes at will.

Thus, the number of voids is preferably 4.

According to example 2, the effect of reducing the torque ripple can be increased by setting the number of voids per 1 pole to 4.

[ example 3]

Fig. 5 is a view showing an outer rotor type surface magnet rotating electric machine according to embodiment 3. In example 2, the effect of reducing the torque ripple was examined 6 times, and here, the effect of reducing the torque ripple due to irregularities of the rotating electric machine was examined.

In the case of a 10-pole 12-slot external rotor surface magnet rotating electrical machine, 2-order and 2.4-order torque ripples are generated due to irregularities of the rotating electrical machine. As shown in fig. 5, the shortest distance from the center of the permanent magnet 3 to the gap is W1, and the shortest distance from the end of the permanent magnet 3 to the gap is W2.

Fig. 6 shows a comparison of the torque pulsation in the case where W1 > W2 and the torque pulsation in the case where W1< W2. When a plurality of gaps are present, the largest gap is targeted, and when a plurality of gaps of the same size are present, the gap closest to the center of the magnet is targeted.

As shown in fig. 6, when W1< W2, the effect of reducing torque ripple caused by irregularities in the rotating electric machine is greater. Therefore, in order to reduce the torque ripple caused by the irregularity of the rotating electric machine, it is preferable to set W1< W2.

According to embodiment 3, the effect of reducing the torque ripple can be increased by adjusting the positional relationship between the permanent magnet and the air gap.

[ example 4]

Fig. 7 is a view showing an outer rotor type surface magnet rotating electric machine according to example 4. Fig. 7 is an axial cross-sectional view, 1/2, radial. In fig. 7, the hatched portion indicates that the structure is rotating. The rotor 4 is disposed on the rotor frame 10, and the stator 7 is disposed on the stator frame 11.

The rotor frame 10 is connected to a shaft 12 and to the stator frame 11 via a bearing 13. The axial direction is the length direction of the shaft 12. Here, an auxiliary bearing 14 may be provided for holding the shaft.

In the gaps shown in examples 1 to 3, the high thermal conductive members 15 such as heat pipes are disposed and extend to the outside of the rotor 4 of the high thermal conductive members 15. The permanent magnet is limited in use temperature, and when the temperature is high, the performance is deteriorated due to irreversible demagnetization. In addition, the temperature of the permanent magnet is not fixed but distributed in the axial direction.

Therefore, only the portion of the permanent magnet having the highest temperature is likely to irreversibly reduce the magnetic flux, and therefore, it is desirable that the magnet temperature be uniform.

Therefore, according to embodiment 4, by providing the high thermal conductive member 15 in the gap, the thermal resistance in the axial direction of the permanent magnet is reduced, and the magnet temperature can be made uniform.

Further, by attaching fins or the like to the end of the high thermal conductive member 15, the heat radiation area is increased, and further, the heat transfer rate is increased by the circumferential velocity generated by the rotation, so that the magnet temperature can be effectively reduced.

Although fig. 7 shows a structure in which the shaft rotates, a structure in which the shaft having a bearing connected between the rotor frame 10 and the shaft 12 does not rotate can obtain the same effect.

[ example 5]

Fig. 8 is a diagram showing example 5 in which the external rotor surface magnet rotating electrical machine according to example 4 is applied to an elevator hoisting machine. Fig. 8 shows only 1/2 in a radial cross section, and hatching is drawn on the rotating portion.

As shown in fig. 8, the power for winding up the rope 16 connected to the car includes an external rotating surface magnet rotating electric machine 1, a sheave 17 on which the rope 16 for the elevator is wound, and a brake 18 for mechanically stopping the rotation.

According to embodiment 5, the torque ripple of the outward turning type surface magnet rotating electric machine is reduced, and therefore the riding comfort of the elevator can be improved.

Description of reference numerals

The motor comprises a 1 … external rotation type surface magnet rotating motor, a 2 … rotor core, a 3 … permanent magnet, a 4 … rotor, a 5 … stator core, a 6 … coil, a 7 … stator, an 8 … groove, a 9 … gap, a 10 … rotor frame, a 11 … stator frame, a 12 … shaft, a 13 … bearing, a 14 … auxiliary bearing, a 15 … high heat-conducting component, a 16 … steel wire rope, a 17 … rope wheel and an 18 … brake.

Claims

1. An external rotation type surface magnet rotating electrical machine, comprising:

a rotor having a rotor core and a permanent magnet disposed on an inner diameter side of the rotor core; and

a stator having a stator core disposed on an inner diameter side of the rotor with a gap therebetween and a coil attached to the stator core,

the rotor core has a plurality of gaps for every 1 pole on the outer diameter side of the surface on which the permanent magnets are mounted.

2. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the permanent magnets are arranged at 1 pole or more, and are circumferentially arranged with a substantially constant space from the permanent magnets of the adjacent magnetic poles.

3. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the voids are not connected to each other.

4. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the air gap of each 1 pole is arranged symmetrically with respect to the center of the permanent magnet.

5. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the gap is filled with a non-magnetic body.

6. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the number of said voids per 1 pole is 4.

7. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

when the distance between the center of the permanent magnet and the gap is W1 and the distance between the end of the permanent magnet and the gap is W2, W1< W2.

8. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the gap is provided with a high heat conduction member such as a heat pipe.

9. A traction machine for an elevator is characterized in that:

the rotating electric machine with the external turning type surface magnet of claim 1 is used as a power for winding up a wire rope connected to a car.

10. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the voids have a semi-circular, circular or trapezoidal shape.

11. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the radius of curvature of the gap side of the stator core is smaller than the radius of the stator.

12. The external turning type surface magnet rotating electrical machine according to claim 1, wherein:

the coil is disposed in a slot of the stator core.