CN112186922B

CN112186922B - External rotating surface magnet rotary motor

Info

Publication number: CN112186922B
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: 2023-06-13
Anticipated expiration: 2040-06-01
Also published as: JP7217205B2; JP2021010284A; CN112186922A

Abstract

The invention provides an external rotating surface magnet rotating motor and a traction machine for an elevator, which reduce adverse effects of magnet breakage and increase of magnetic resistance and reduce torque pulsation, wherein the external rotating surface magnet rotating motor comprises a rotor with a rotor core and a permanent magnet arranged on the 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, 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 magnets are attached.

Description

External rotating surface magnet rotary motor

Technical Field

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

Background

As the rotary electric machine as the electromechanical energy conversion device is incorporated in various devices, miniaturization of the rotary electric machine is also demanded along with miniaturization of the devices. As one mode of downsizing of the rotary electric machine, an external-rotation type permanent magnet rotary electric machine is used. The external rotating permanent magnet rotary electric machine has a structure in which a rotor having permanent magnets mounted thereon is disposed on the outer peripheral side of a stator having coils mounted thereon. An external-rotor permanent magnet rotary electric machine has a larger radius of a rotor-stator gap (gap) than an internal-rotor permanent magnet rotary electric machine, and the rotor is located outside and has a longer circumference of 1 pole, so that a magnet having a large area as viewed in the radial direction can be disposed. This can achieve a high output and a small-sized rotating electrical machine.

Since the rotor core is located on the outer peripheral side of the magnet, the external rotating permanent magnet rotary electric machine has few problems in holding the magnet against centrifugal force, and therefore, surface magnet type rotary electric machines are often used. By using the surface magnet, the short circuit of the magnetic flux in the rotor core is reduced, and therefore the effective magnetic flux can be increased, and the high output can be achieved.

As a problem of the rotating electrical machine, there is a decrease in torque pulsation. Torque ripple refers to the pulsation of torque. Torque pulsation causes vibration and noise of the driving device.

As for torque pulsation reduction, there is a technique described in patent document 1. The rotor of the rotating electrical machine includes a substantially annular rotor core having a plurality of magnet insertion holes formed at predetermined intervals in the 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 plurality of electromagnetic steel plates, and has a hole portion on the outer peripheral side of the magnet insertion hole of the rotor core, the hole portion being located on the substantially d-axis of each magnetic pole portion made of a permanent magnet.

Further, there is a technique described in patent document 2 regarding torque pulsation reduction. The method is characterized in that: the magnetic field generator is provided with a magnet holding part and a magnetic field generating part, wherein the magnet holding part comprises a multipolar magnetized magnet with a cylindrical shape and a back yoke which is arranged to be abutted against one surface of the magnet in the radial direction, the magnetic field generating part is positioned at a position opposite to the other surface of the magnet, the main shaft motor is rotatably provided with any component of the magnet holding part and the magnetic field generating part, and the back yoke is provided with a concave part along the boundary line of the adjacent magnetic poles of the magnet on the surface abutted against the magnet.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2018-137924

Patent document 2: japanese patent laid-open No. 2001-57752

Disclosure of Invention

Problems to be solved by the invention

In patent document 1, torque pulsation is reduced by providing a gap on the slit side of the magnet. However, in the surface magnet type, the magnet faces the slit, so that it is difficult to cope with the problem.

In patent document 2, torque pulsation is reduced by providing a groove (nonmagnetic portion) on the outer shape side of the end portion of the magnet. However, since the magnetic resistance is increased by the nonmagnetic portion, the magnetic flux at the end of the magnet cannot be effectively utilized. In addition, when the magnet is impacted for some reason, the possibility of breakage of the magnet increases because the number of members holding the magnet is small.

The present invention provides an external-rotation-type surface magnet rotating electrical machine which reduces adverse effects of breakage of a magnet and an increase in magnetic resistance and reduces torque pulsation.

Technical scheme for solving problems

A preferred example of the present invention is 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 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, adverse effects of breakage of the magnet and increase in magnetic resistance can be reduced, and reduction in torque pulsation can be achieved.

Drawings

Fig. 1 is a view showing a radial cross section of an external-rotation-type surface-magnet rotary electric machine in example 1.

Fig. 2 is a view showing an enlarged radial cross section of the void in example 1.

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

Fig. 4 is a graph showing torque pulsation with respect to the number of voids in example 2.

Fig. 5 is a view showing an enlarged radial cross section of the void in example 3.

Fig. 6 is a graph showing torque pulsation with respect to the void position in example 3.

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

Fig. 8 is a view showing a cross section in the axial direction of the elevator hoisting machine in example 5.

Detailed Description

The embodiments are described below based on the drawings.

Example 1

Fig. 1 shows an embodiment 1 of an external-rotor-type surface-magnet rotary electric machine according to the present invention. Fig. 1 is a radial sectional view of an external-rotation-type surface-magnet rotary electric machine. Radial refers to a direction from the center to the periphery of fig. 1. The external-rotor-type surface-magnet rotary electric 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 with a predetermined gap provided on an inner diameter side of the rotor 4.

Here, the permanent magnet 3 is preferably a surface magnet 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 of the short-circuited magnet flux in the rotor can be reduced, and the effective flux can be increased, so that the high output can be achieved.

The coil 6 is preferably attached to the stator core 5 by concentrated winding. This shortens the length of the axial end of the coil 6, shortens the axial length of the external-rotation-type surface-magnet rotary electric machine 1, and can be miniaturized. Further, it is preferable that the portion (slot 8) of the stator core 5 where the coil 6 is disposed is an open slot. This facilitates insertion of the coil 6 and improves the assemblability.

Further, the radius of curvature in the vicinity of the clearance 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 the magnetic resistance in the circumferential direction, and can reduce torque pulsation.

Here, a gap 9 is provided on the outer diameter side of the mounting surface of the rotor core 2 on which the permanent magnet 3 is mounted. Fig. 2 shows an enlarged view of the vicinity of the gap 9. By providing the gap, the change in magnetic resistance when viewed from the stator side is leveled, and the harmonic component overlapping the magnetic flux is reduced, thereby reducing torque ripple. In fig. 2, the gaps 9 are arranged 2 for each magnet.

If the number of voids 9 is 1, there is a possibility that the voids become larger because they are located at void positions where the torque pulsation can be optimally reduced. Since the void 9 is a nonmagnetic portion, it becomes magnetic resistance as viewed from the magnet. As the voids become larger, the magnetic resistance also becomes larger, and thus the electrical characteristics are degraded. On the other hand, when more than 2 voids are formed without touching each other, the voids are magnetic bodies and can pass through the magnetic flux, so that the decrease in electrical characteristics can be reduced.

Further, since the gap is formed without forming the recess and the groove, the shape of the arrangement portion of the magnet is fixed, and therefore, the manufacturing method does not need to be changed, and the risk of breakage of the magnet due to impact is the same as in the conventional art, and therefore, the present structure can be easily applied.

Fig. 1 shows a 40-pole 48-slot external-rotation-type surface-magnet rotary electric machine, but the present invention is not limited to this shape, and similar effects can be obtained by other slot combinations. In the case of the external rotary electric machine having double rotation, it is preferable that the 2 gap positions are symmetrical with respect to the central axis of the permanent magnet 3 as shown in fig. 2.

Further, the air does not need to be filled in the space, and a nonmagnetic material such as a resin may be used. The shape of the void is not limited, and may be a semicircle, a circle, a triangle, a trapezoid, or the like in fig. 2. Furthermore, the size and shape of the gap do not need to be unified within 1 magnetic pole, and the size, shape and position of the gap can be changed according to each magnetic pole. The permanent magnets 3 may be arranged in the circumferential direction so that a space substantially fixed to the permanent magnets of the adjacent poles is maintained, with 1 or more permanent magnets being arranged for each 1 pole.

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 magnet 3 is mounted, and the possibility of damage to the magnet can be reduced without affecting the member holding the magnet. Further, it is possible to reduce the adverse effect of the increase in magnetic resistance and achieve a reduction in torque pulsation.

Example 2

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

In addition, as described above, the torque ripple reduction effect varies depending on the gap position. Therefore, the void position and size are defined on the same basis by the optimization method. As is clear from fig. 4, by setting the number of voids to 2 to 4, the torque pulsation is reduced, and the effect of reducing the torque pulsation is greatly increased.

However, the variation in the torque pulsation reducing effect is small when the number of voids is made to be 4 to 6. The number of processing times increases when the voids are increased, and there is a possibility that the cost increases, so that it is not preferable to increase arbitrarily.

Thus, the number of voids is preferably 4.

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

Example 3

Fig. 5 is a diagram showing an external rotating surface magnet rotary electric machine according to example 3. In example 2, the effect of reducing torque pulsation caused by irregularities in the rotating electrical machine was studied 6 times.

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

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

As is clear from fig. 6, the effect of reducing the torque ripple caused by the irregularities of the rotating electrical machine is greater in the case where W1< W2. Accordingly, W1< W2 is preferable in order to reduce torque pulsation caused by irregularities in the rotating electrical machine.

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

Example 4

Fig. 7 is a diagram showing an external rotating surface magnet rotary electric machine according to example 4. FIG. 7 is an axial cross-sectional view, 1/2 of the radial direction. The hatched portion in fig. 7 indicates that this is a rotating structure. The rotor 4 is disposed on a rotor frame 10, and the stator 7 is disposed on a stator frame 11.

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

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

Accordingly, only the portion of the permanent magnet having the highest temperature may irreversibly reduce the magnetic field, and therefore, the magnet temperature is desired to be uniform.

Therefore, according to embodiment 4, by providing the high heat 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 portions of the high heat conductive member 15, the heat dissipation area increases, and the heat transfer rate is increased by the peripheral speed generated by the rotation, so that the magnet temperature can be effectively reduced.

In addition, although fig. 7 shows a structure in which the shaft rotates, a structure in which the shaft with a bearing connected between the rotor frame 10 and the shaft 12 does not rotate can achieve the same effect.

Example 5

Fig. 8 is a view showing example 5 in which the external rotating surface magnet rotating electric machine of example 4 is applied to an elevator hoisting machine. In fig. 8, only 1/2 of the radial cross section is shown, and hatching is drawn on the rotating portion.

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

According to embodiment 5, torque pulsation of the external-rotation-type surface magnet rotating electric machine is reduced, and thus riding comfort of the elevator can be improved.

Description of the reference numerals

1 … external rotation surface magnet rotating electrical machine, 2 … rotor core, 3 … permanent magnet, 4 … rotor, 5 … stator core, 6 … coil, 7 … stator, 8 … slot, 9 … gap, 10 … rotor frame, 11 … stator frame, 12 … shaft, 13 … bearing, 14 … auxiliary bearing, 15 … high thermal conductive component, 16 … wire rope, 17 … sheave, 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 each 1 pole on the outer diameter side of the surface on which the permanent magnet is mounted,

let W1 be the shortest distance between the center of the permanent magnet and the gap, and W2 be the shortest distance between the end of the permanent magnet and the gap, W1< W2.

2. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the permanent magnets are arranged at 1 or more per 1 pole, and are arranged in the circumferential direction with a certain space from the permanent magnets of adjacent magnetic poles.

3. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the voids are not connected to each other.

4. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the gaps of each 1 pole are symmetrically arranged about the center of the permanent magnet.

5. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the gaps are filled with a nonmagnetic material.

6. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the number of said voids per 1 pole is 4.

7. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

a heat pipe as a high heat conduction member is disposed in the gap.

8. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

the void has a semicircular, circular, or trapezoidal shape.

9. An external rotary surface magnet rotary electric 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.

10. An external rotary surface magnet rotary electric machine according to claim 1, wherein:

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

11. A traction machine for an elevator, characterized in that:

a rotary electric machine having the external rotating surface magnet of claim 1 as a motive force for winding up a wire rope connected to a car.