JP2002044887A - Motor rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor rotor which can secure required magnetic flux in excellent distribution, is improved in shearing strength at a reduced cost, and suitable for a high speed motor. SOLUTION: This rotor has magnetic poles provided on its periphery with their polarities changed alternately and is fastened on a shaft 2. The magnetic poles consist of plural magnets 3 arranged circularly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for a motor, and more particularly to a rotor used for an inner rotor type motor that rotates at a high speed.

[0002]

2. Description of the Related Art In general, a motor rotor has a plurality of magnetic poles which are fixed to a shaft and are alternately different in a circumferential direction. And the first of the conventional motor rotors
As a conventional example, as shown in FIG.
A plurality (four) of magnetized arc-shaped magnets 43 are formed on the outer periphery of a rotor main body (cylindrical laminated iron core) 42, which is independently supported, and form a magnetic pole independently of each other. The outer periphery is held by a non-magnetic cylindrical scattering prevention cover 44 (Japanese Patent Application Laid-Open Nos. 10-210692 and 10-02).
No. 8344).

As a second conventional example, as shown in FIG. 4 (B), a plurality of (four) arc-shaped members are provided on an outer peripheral portion of a rotor body (cylindrical laminated core) 42 supported by a shaft 41. Hole
45 are provided at equal intervals, and a plurality (four) of magnetized arc-shaped magnets 43... (In a buried state) which individually form magnetic poles are inserted into the holes 45, respectively. It is a structure that is fixed with such as.

As a third conventional example, as shown in FIG. 4 (C), a plurality (four) of rectangular bodies are provided on the outer peripheral portion of a rotor body (cylindrical laminated core) 42 supported by a shaft 41. Shaped holes 45 are provided at equal intervals, and a plurality of (four) magnetized substantially rectangular (substantially rectangular parallelepiped) magnets 43. (Embedded) and fixed with an adhesive or the like.

In short, in the first, second, and third conventional examples, the conventional motor rotor has a plurality of magnetic poles that are alternately arranged in the circumferential direction, each of which is constituted by one magnet 43. .

[0006]

However, the first conventional example has a problem that the scattering prevention cover 44 is required, and the number of parts and the number of assembling steps are increased. Also, when applied to a motor rotating at high speed (for example, 60,000 RPM),
In order to prevent the magnet 43 from scattering or deforming due to the rotation of the rotor, it is necessary to increase the thickness of the scattering prevention cover 44, the amount of magnetic flux from the magnet 43 is reduced, and the waveform of the magnetic circuit on the rotor side is deteriorated. Problems arise.

In the first and second conventional examples,
An expensive neodymium (Nd-
When using a Fe—B) sintered magnet, since the magnet 43 is formed in an arc shape in a plan view, the neodymium sintered magnet needs to be processed (polished) in an arc shape, resulting in a high cost. Occurs.

In the third conventional example, since the magnet 43 is formed in a rectangular plate shape, the distance d from the outer peripheral surface of the rotor body 42 corresponding to the center of the magnetic pole to the center of the magnet 43 is the shortest. As a result, the magnetic flux in this portion is weakened, which causes a problem that the rotation performance of the rotor is deteriorated. Further, since the angle θ formed by the two adjacent magnets 43 is small and the portion between the adjacent substantially rectangular holes 45 in the rotor main body 42 protrudes sharply in the radial direction, the magnetic pole portion in the rotor main body 42 is formed. The shear strength due to the centrifugal force of the portion 49 (dotted portion) is weakened, and the magnetic pole portion 49 is liable to be deformed or damaged during high-speed rotation, which may cause the magnet 43 to crack or chip.

In the present invention, the required amount of magnetic flux can be secured, a good magnetic flux distribution can be obtained, the shear strength of the portion between the magnetic poles of the rotor body can be improved, and the cost can be reduced. An object is to provide a motor rotor suitable for a rotary motor.

[0010]

In order to achieve the above-mentioned object, a motor rotor according to the present invention is a motor rotor having a plurality of magnetic poles which are fixed to a shaft and are alternately different in a circumferential direction. Each of the magnetic poles is constituted by a plurality of flat plate-shaped magnets arranged in a line in a circumferential direction of the rotor main body.

With this configuration, a necessary magnetic flux amount can be secured and a good magnetic flux distribution can be obtained. In particular, even when the number of poles is low, such as a two-pole motor, a trapezoidal wave (or a sine wave) is obtained. The magnetic flux distribution can be improved. Therefore,
By using a two-pole motor, the timing of switching the energization to the multi-phase coil of the stator according to the rotational position of the rotor can be eased, and high-speed rotation (for example, 60,000 R
PM) capable motors can be provided.

Further, it is possible to improve the shear strength of the portion between the magnetic poles (between the magnets) of the rotor body, to suppress the deformation and breakage of the rotor body due to the centrifugal force of the magnet during high-speed rotation, and to prevent the magnet from cracking. , Chipping, deformation, etc.) can be prevented.

Furthermore, since the magnet has a simple flat plate shape with a single character in a plan view, when a neodymium sintered magnet is used for the magnet, it is not necessary to specially process the neodymium sintered magnet and to reduce the size. And cost can be reduced.

In addition, since the magnet is embedded in the rotor body, the magnet can be easily mounted on the rotor body, and the magnet can be made strong. In addition, scattering and deformation of the magnet due to rotation of the rotor can be prevented.

Further, a motor rotor according to the present invention is a motor rotor having a plurality of magnetic poles fixed to a shaft and alternately different in a circumferential direction.
It is composed of a plurality of flat-plate-shaped magnets arranged in a single character in plan view arranged in a buried manner in the circumferential direction of the rotor body, and the arrangement shape of all magnets is a substantially polygonal shape almost inscribed on the outer periphery of the rotor body in plan view. It is formed so that it becomes.

With this configuration, a necessary magnetic flux amount can be secured and a good magnetic flux distribution can be obtained. In particular, even when the number of poles is low, such as in a two-pole motor, a trapezoidal wave (or a sine wave) is obtained. The magnetic flux distribution can be improved. Therefore,
By using a two-pole motor, the timing of switching the energization to the multi-phase coil of the stator according to the rotational position of the rotor can be eased, and high-speed rotation (for example, 60,000 R
PM) capable motors can be provided.

Further, the arrangement of all magnets is
Since the magnet is formed so as to have a substantially polygonal shape substantially inscribing the outer periphery of the rotor main body, the magnet can be brought close to the outer periphery of the rotor main body, and the required amount of magnetic flux can be secured more reliably.

Further, the shear strength of the portion between the magnetic poles (the portion between the magnets) of the rotor body can be improved, thereby suppressing the deformation and breakage of the rotor body due to the centrifugal force of the magnet during high-speed rotation. , Chipping, deformation, etc.) can be prevented.

Furthermore, since the magnet has a simple flat plate shape with a single character in a plan view, when a neodymium sintered magnet is used as the magnet, it is not necessary to specially process the neodymium sintered magnet and to reduce the size thereof. And cost can be reduced.

Moreover, since the magnet is buried in the rotor body, the magnet can be easily mounted on the rotor body and can be made strong. In addition, scattering and deformation of the magnet due to rotation of the rotor can be prevented.

In the motor rotor according to the present invention, the magnet is a neodymium sintered magnet. Therefore, the magnet has a high coercive force, and the performance of the motor is further improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments.

FIG. 1 is a front sectional view showing an embodiment of a motor rotor according to the present invention. The rotor 1 is applied to an inner rotor type motor. That is, the motor includes a bottomed (circular) cylindrical motor case 10, and a bracket 11 for covering the upper end opening of the motor case 10, and a shaft 2 inserted through the inside of the motor case 10 and the center of the bracket 11. One end (lower) is attached to the bottom of the motor case 10 and the other end (upper) is attached to the center of the bracket 11 via bearings 12 and 12 so as to be rotatable around the axis. I have.

A shaft 2 is provided at the center of the rotor 1.
Are fixed in a penetrating manner. Radially outward of the rotor 1, a stator attached to the inner surface of the motor case 10.
14 are arranged. The stator 14 is configured by mounting insulators 13, 13 from above and below on a stator core formed by laminating electromagnetic steel sheets, and winding a coil around each tooth portion of the stator core in this state. Above the rotor 1, an annular back yoke 15 fixed to the shaft 2 is provided.

The back yoke 15 for detecting the rotor position includes
An annular sensor magnet 16 is attached, and the sensor magnet 16 is provided with, for example, magnetic poles formed to be equal to the pitch of the magnetic poles of the rotor 1. A sensor 17 (such as a Hall element, a Hall IC, a magnetoresistive element, etc.) is mounted on a substrate 18 so as to face the sensor magnet 16 in the axial direction.

The position of the magnetic pole of the rotor 1 is detected by the sensor 17 via the sensor magnet 16 and the phase currents to the coils of the stator 14 are switched. Can be rotated. That is, when rotating the shaft 2, the sensor
Based on the position of the magnetic pole of the rotor 1 detected by 17, the control circuit board 19 sends an electric current to the stator 14 to excite it.

As shown in FIGS. 1 and 2, the rotor 1
It has a plurality of magnetic poles that are fixed to the shaft 2 and that are alternately different in the circumferential direction. And each magnetic pole is the rotor main body 1a.
Are arranged in a buried manner in the circumferential direction, and are formed of a plurality of flat-plate-like (substantially rectangular-plate-like) magnets 3 having a single character in plan view. That is, in the present embodiment, one magnetic pole is composed of two magnets 3 and 3, and the rotor 1 is composed of four magnetic poles (four poles) and has eight magnets 3.

More specifically, the present rotor 1 includes a rotor body 1a and a plurality of magnets 3. The rotor main body 1a is a cylindrical laminated iron core formed by laminating a number of thin iron plates punched into a predetermined shape, and a plurality of (e.g., 8 in this embodiment)
) Are provided. The magnets 3 are formed in a flat plate shape (substantially rectangular plate shape) having a single character in plan view, inserted (embedded) into the holes 4 of the rotor main body 1a, and fixed by an adhesive or the like.

All the magnets 3 are formed so as to have a substantially polygonal shape (octagonal shape in the present embodiment) substantially inscribing the outer periphery of the rotor body 1a in plan view. That is, as shown in FIG. 2, a virtual polygon B composed of radially outer sides of all the magnets 3 arranged in contact with the outer periphery of the rotor body 1a.

The magnet 3 is made of neody (Nd-F)
e-B) It is preferable to use a sintered magnet, which has a high coercive force and has the effect of further improving the performance of the motor.
At this time, since the magnet 3 has a simple shape of a substantially rectangular plate, there is no need to specially process the neodymium sintered magnet, and the magnet can be reduced in size, and cost (such as material cost) can be suppressed. it can.

As described above, the magnet 3 is attached to the rotor body 1
a, the magnet 3 is attached to the rotor body 1
In addition, the magnet 3 can be easily attached to the magnet 3a, and the attachment state of the magnet 3 becomes strong, and the scattering and deformation of the magnet 3 due to the rotation of the rotor 1 can be reliably prevented.

Further, since all the magnets 3 (in a single character in plan view) are arranged close to (in the circumferential direction) the outer peripheral surface of the rotor main body 1a, the stator 3 extends over the entire circumference of the rotor main body 1a. 14, the required magnetic flux amount can be secured and a good magnetic flux distribution can be obtained.
It will be excellent.

Further, since the angle θ formed by the two adjacent magnets 3 becomes large, stress concentration hardly occurs in a portion corresponding to the adjacent magnets 3 in the rotor main body 1a. The shear strength due to the force can be improved, and the deformation and breakage of the portion between the magnets 3 and 3 can be prevented during high-speed rotation of the rotor 1,
It is possible to prevent the magnet 3 from being damaged or broken (such as cracking, chipping or deformation).

Next, FIG. 3 shows another embodiment of the present rotor 1, and the following configuration is different from FIG.

That is, in FIG. 2, the present rotor 1 is constituted by four magnetic poles (four poles), but in FIG. 3, the present rotor 1 is constituted by two magnetic poles (two poles).
One magnetic pole is composed of four magnets 3.

As described above, even when a two-pole motor having a small number of poles is used, a necessary amount of magnetic flux can be secured to the stator 14 over the entire circumference of the rotor main body 1a. A distribution can be obtained.

Therefore, by using a two-pole motor, the timing of switching the energization to the multi-phase coil of the stator 14 according to the rotational position of the rotor 1 can be eased, and high-speed rotation (for example, 60,000 RPM) is possible. Motor can be provided. For example, in the case of an 8-pole motor in which eight magnets constitute individual magnetic poles, high-speed rotation (for example, 60,000 RPM) cannot be performed in time for switching (energization switching), and high-speed rotation becomes impossible. Although it is conceivable that such a problem is solved in the case of FIG.

In short, the present rotor 1 makes it possible to manufacture a two-pole motor, and achieves high speed (about 40,000 to 80,000 RPM).
A motor that can rotate and has stable performance.
IPM (Embedded magnet structure motor)} can be realized.

It should be noted that the present invention is not limited to the above-described embodiment, and may be a motor having a number of magnetic poles other than those described above. The same effect as described above can be obtained by configuring each magnetic pole with a plurality of magnets. The magnet 3 may be arranged near the inner periphery of the rotor body and applied to the outer rotor, and the design can be changed without departing from the gist of the present invention.

[0040]

According to the present invention, the required amount of magnetic flux can be secured, a good magnetic flux distribution can be obtained, and the performance of the motor can be improved. Further, the shear strength of the rotor body 1a is improved, and the rotor body 1a is excellent in durability. Further, costs are reduced. In particular, it becomes suitable for a high-speed rotation motor.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is a plan sectional view of the present invention.

FIG. 3 is a plan sectional view showing another embodiment of the present invention.

FIG. 4 is a plan sectional view showing a conventional example.

[Explanation of symbols]

 1a Rotor body 2 Shaft 3 Magnet

Continuing from the front page (72) Inventor Yoshihide Nakamura 248 Nakajuku, Aichigawa-cho, Aichi-gun, Aichi-gun, Shiga F-term in Nidec Shiga Technology Development Center (reference) 5H002 AA01 AA07 AA08 AB01 AB07 AE07 AE08 5H019 AA04 AA10 BB01 BB05 BB14 BB19 BB22 CC03 CC06 CC09 5H622 AA03 CA02 CA05 CA07 CA10 CA13 CA14 DD02 PP03 PP07 PP10

Claims (3)

[Claims] 1. A motor rotor having a plurality of magnetic poles fixed to a shaft and alternately different in a circumferential direction, wherein each of the magnetic poles is arranged in a buried manner in a circumferential direction of a rotor main body. A motor rotor comprising a single-character plate-shaped magnet. 2. A motor rotor having a plurality of magnetic poles fixed to a shaft and alternately different in a circumferential direction, wherein each of the magnetic poles is arranged in a buried manner in a circumferential direction of a rotor main body. A motor rotor comprising a single-character plate-shaped magnet, wherein all magnets are formed in a substantially polygonal shape that is substantially inscribed in the outer periphery of the rotor body in plan view. 3. The motor rotor according to claim 1, wherein the magnet is a neodymium sintered magnet.