JP3872460B2 - Sintered ring magnet, method of manufacturing the same, and motor using the sintered ring magnet - Google Patents

Description

  The present invention relates to an anisotropically oriented sintered ring magnet used for an inner rotor of a permanent magnet motor.

  Radially oriented ring magnets used in the inner rotor of permanent magnet motors often perform skew magnetization in which magnetic poles are formed obliquely with respect to the axial direction in order to reduce rotational unevenness such as cogging torque. However, since the magnetomotive force distribution of a radially oriented ring magnet is rectangular, when this magnet is used in the inner rotor of a permanent magnet motor, it contains many higher-order components and cogging torque is sufficient with skew magnetization alone. In many cases, the effect of reducing the above cannot be obtained.

  Therefore, in the resin magnet, there is a method of forming irregularities on the outer periphery of the ring magnet and further skewing the irregularities in the axial direction. According to this method, the distortion of the magnetization distribution in the rotation direction can be reduced, and the cogging torque can be further reduced by the skew of the concavo-convex portion (see, for example, Patent Document 1).

  Magnets used for the inner rotor of the permanent magnet motor include polar-oriented polar anisotropic magnets in addition to the above-described radial-oriented magnets. According to the polar orientation, the magnetomotive force distribution approaches a sine wave, the distortion is reduced, and the cogging torque is reduced. Furthermore, if skew magnetization is possible, the cogging torque can be further reduced, but the polar anisotropic magnet is oriented so that the magnetic flux returns from the outer circumference of the magnet to the outer circumference through the inside of the magnet. N / S poles cannot be set at various locations, and skew magnetization cannot be performed.

  Therefore, a magnet is disclosed in which a polar anisotropic magnet is divided into two or more in the axial direction, and the divided polar anisotropic magnet is shifted in the circumferential direction and skewed by a half cycle of an angle determined by cogging torque or more. (For example, refer to Patent Document 2).

JP-A-9-35933 (page 3-6, FIGS. 1 to 4) JP 2001-314050 A (page 4-5, FIG. 5)

  The conventional resin magnet can reduce the cogging torque due to the skew of the concavo-convex portion after reducing the distortion of the magnetization distribution in the rotation direction, but requires a special extrusion molding machine. Since a magnetic field cannot sometimes be applied, there is a problem that anisotropic orientation cannot be performed, and it cannot be applied to a small and high output motor that requires a strong magnet.

  In the polar anisotropic magnet, although the magnetization distribution approaches a sine wave and distortion is reduced and the cogging torque is reduced, the two magnets fixed to the rotor are magnetized in two steps or fixed. Need to be magnetized before. Since the magnetized magnet is fixed, there is a problem that it is difficult to accurately arrange the magnet at a predetermined skew angle due to the attractive force and repulsive force of the magnet, and the motor manufacturing process is complicated.

  The present invention provides a ring magnet that can be easily magnetized after rotor assembly and can be anisotropically oriented, and that can reduce cogging torque by reducing distortion and skewing of the magnetization distribution in the rotational direction. It is for the purpose of provision.

The first method for producing a sintered ring magnet according to the present invention is a method for producing a sintered ring magnet in which a plurality of ring-shaped rings are axially stacked and integrated by sintering.
A step of individually forming a ring including at least two rings in which notch portions of the same shape extending in the axial direction on the outer circumferential surface thereof are periodically formed in the circumferential direction, and performing radial orientation;
The at least two rings formed with the notches are adjacent to each other, and the plurality of rings are arranged so that the positions of the notches are shifted from each other between the two adjacent rings at a predetermined rotation angle in the circumferential direction. The process of stacking,
Sintering the plurality of stacked rings;
The ring in which the notch is formed has a step of skew magnetizing the sintered ring so that the skew angle changes in the axial direction so that the notch becomes a boundary line of the magnetic pole. It is.

In the sintered ring magnet according to the present invention, a plurality of ring-shaped rings are stacked in the axial direction and integrated by sintering.
A plurality of the rings are formed with notches of the same shape extending in the axial direction on the outer peripheral surface thereof periodically in the circumferential direction,
The positions of the notches are stacked at a predetermined rotational angle in the circumferential direction between two adjacent rings formed with the notches,
A ring in which the notch is not formed is disposed between two adjacent rings in which the notch is formed;
In each ring in which the notch is formed , the center line parallel to the axial direction of the notch is a boundary line of the magnetic pole, and in the ring in which the notch is not formed, the boundary line of the magnetic pole Is magnetized so as to be skewed with respect to the axial direction.

The motor according to the present invention uses the sintered ring magnet according to the present invention for the rotor.

A second method for producing a sintered ring magnet according to the present invention is the method for producing a sintered ring magnet in which a plurality of ring-shaped rings are stacked in the axial direction and integrated by sintering.
A ring including at least two rings in which notch portions of the same shape extending in the axial direction on the outer peripheral surface are periodically formed in the circumferential direction and at least one ring in which the notch portions are not formed. Individually molding and radial orientation;
The at least two rings formed with the notches are adjacent to each other, and the positions of the notches are shifted from each other between the two adjacent rings by a predetermined rotation angle in the circumferential direction. Stacking the plurality of rings such that a ring in which the notch is not formed is disposed;
Sintering the plurality of stacked rings;
In the ring in which the notch is formed, the center line parallel to the axial direction of the notch is the boundary line of the magnetic pole, and in the ring in which the notch is not formed, the boundary line of the magnetic pole is And a step of magnetizing to skew with respect to the axial direction.

According to the sintered ring magnet and method for producing a sintered ring magnet according to the present invention, is easy magnetization after Russia over data assembled, the ring magnet capable of radially aligned, and distortion of the magnetization distribution in the rotational direction The cogging torque can be reduced by reducing.

According to the motor according to the present invention, since the sintered ring magnet according to the present invention is used for the rotor, the magnet is easy to be magnetized after the assembly of the rotor and is capable of anisotropic orientation, and The cogging torque can be reduced by reducing the distortion of the magnetomotive force distribution in the rotational direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention uses a structure in which rings are stacked as a basic component. In the following description, an example in which two to four rings are stacked is shown. Is applicable. Further, although the case where the number of magnetic poles of the ring magnet is six is described, the present invention is not limited to this, and can be applied to a ring magnet having 2n magnetic poles (n is an integer).
FIG. 5 is a block diagram showing a cross section of a motor using the ring magnet of the present invention. As shown in the figure, the motor is generally composed of a rotor composed of a ring magnet 1 and a shaft 3, and a stator composed of a laminated iron core 4 and a coil 5.

Embodiment 1 FIG.
FIG. 1 is a plan view (a) and a side view (b) showing a first embodiment of a sintered ring magnet according to the present invention, and FIG. 2 is a plan view showing an upper ring 2 and a lower ring 2 separately. (A), (c) and side view (b), (d).

  As shown in FIG. 1, the ring magnet 1 is formed by stacking two rings 2 (pairs) in the axial direction and integrating them by sintering. Each ring 2 is radially oriented, and the outer periphery is a straight line. A notch 2a is formed. In this embodiment, the notch 2a serves as the boundary between the magnetic poles, and the magnetic pole is formed in the middle of the adjacent notch 2a.

  As shown in FIG. 2, each ring 2 has the same shape in the axial direction, and is notched in the upper rings 2 (a) and (b) and the lower rings 2 (c) and (d). The parts 2a are rotated and stacked around a shaft by a predetermined angle θ (hereinafter referred to as a rotation angle).

  In an actual motor, the fundamental period component (primary component) of the magnetomotive force distribution waveform corresponds to the repetition period of each magnetic pole, and contributes to the rotation of the motor. In the case of a 6-pole motor, 6 N poles, S It is a component corresponding to the peak of the pole. Mainly third-order, fifth-order, and seventh-order harmonic components cause cogging torque. In particular, the fifth harmonic has a large influence.

  In this embodiment, a linear notch 2a is provided on the outer periphery so as to extend in the axial direction, and the magnetic pole is provided between the notches 2a so that the notch 2a serves as a boundary between the magnetic poles. , The magnetization distribution is large at the center of the magnetic pole and small at the boundary, and it is possible to reduce magnetization distortion such as the third, fifth and seventh harmonic components, and the cogging torque is reduced. .

  Since the cogging torque is generated due to the positional relationship between the rotor magnet and the magnetic pole of the stator, if the upper ring 2 and the lower ring 2 deviate in the rotational direction by the rotation angle θ, the upper ring 2 and the lower ring 2 The generated cogging torque is out of phase. Depending on how the rotation angle θ is selected, the cogging torques cancel each other and become smaller.

  The same effect can be obtained even if the number of stages of the ring 2 is three or more, but the case of two stages is described here.

  Here, the manufacturing method of the ring magnet 1 in this embodiment is demonstrated. A neodymium sintered ring magnet with a large maximum energy product is a process of vacuum casting Nd, Fe, B, etc. at a predetermined composition ratio, a process of pulverizing a cast alloy to produce a finely pulverized powder, and a finely pulverized powder as a predetermined ring. Manufactured through a step of forming a magnetic field into a shape, a sintering / heat treatment step, an outer shape processing step and the like.

  In the magnetic field forming step, a finely pulverized powder is filled in a die having the shape of the ring 2 shown in FIG. 1, and the filled finely pulverized powder is pressed with a punch having the same cross-sectional shape as that of the die to obtain a predetermined density. In addition to forming a molded body, an alignment magnetic field is applied to the molded body to perform alignment treatment. The orientation magnetic field is oriented in the radial direction as the radial direction of the ring.

  The radially oriented shaped bodies are stacked at a rotation angle θ and, if necessary, pressed in the axial direction, and then subjected to sintering and heat treatment to produce a ring magnet in which the ring 2 is integrated. At this stage, since this ring magnet is not magnetized, when it is applied to a motor, it is magnetized after being incorporated in the rotor of the motor.

  As described above, according to this embodiment, since it is radially oriented, it is possible to easily perform skew magnetization even after assembly of the rotor, and it is a ring magnet capable of anisotropic orientation, and a magnetomotive force in the rotational direction. The cogging torque can be reduced by reducing the distortion of the distribution.

Embodiment 2. FIG.
FIG. 3 is a plan view (a) and a side view (b) showing a second embodiment of the sintered ring magnet according to the present invention, and shows the configuration of the ring magnet formed with magnetic poles. In the figure, the same reference numerals as those in the first embodiment denote the same or corresponding parts.

  As shown in FIG. 3, in this embodiment, the notch 2a is an arcuate recess. The arc-shaped notch 2a is a boundary between magnetic poles, and a magnetic pole is formed at an intermediate portion between the notches 2a.

  The groove width W of the notch 2a is selected to be about 2/5 of the width of the magnetic pole (the width between the center of the notch 2a and the center of the adjacent notch 2a) (the error of the groove width W is ± 15). In the% range, the fifth harmonic component is 10% or less). The minimum thickness of the ring 2 in the notch 2a is mb, and the thickness of the ring 2 between the notches 2a is mr.

  FIG. 4 is a diagram showing the relationship between the amplitude of the fundamental wave component of the magnetomotive force distribution and the amplitudes of the third, fifth and seventh harmonic components with respect to mb / mr. In the figure, a negative amplitude value indicates that the phase is inverted.

  From FIG. 4, mb / mr is about 0.5, that is, the fifth order that greatly affects the generation of cogging torque by selecting the thickness of the notch 2a to be half the thickness of the ring 2 between the notches 2a. It can be seen that harmonics can be greatly suppressed.

  In the case where it is more effective to reduce the third harmonic or the seventh harmonic, the groove width W of the notch 2a is set to 2/3 of the magnetic pole width and the seventh harmonic relative to the third harmonic. By selecting 2/7 of the magnetic pole width with respect to the wave, it is possible to suppress the third-order harmonic or the seventh-order harmonic that affects the generation of cogging torque.

Embodiment 3 FIG.
In the motor shown in FIG. 5, the basic cogging torque includes vibrations corresponding to the least common multiple m of the number of magnetic poles X of the rotor ring magnet 1 and the number of slots Y of the stator per one rotation of the motor. . Here, X is a multiple of 2 and Y is a multiple of 3.

  The rotation angles in the upper and lower rings 2 shown in FIG. 1 are defined as a half cycle of this basic cogging torque. That is, by setting the rotation angle to 360/2 m [°], the cogging torques of the upper and lower rings 2 cancel each other, so that the cogging torque generated as a motor is suppressed. In some cases, the rotation angle is more effective than the rotation angle due to the influence of magnetic interference.

  For example, in the case of a 6-pole, 9-slot motor, 18 cycles of cogging torque are generated per revolution. By setting the rotation angle in the upper and lower rings 2 to 10 °, the cogging torque of each ring 2 cancels out and the total cogging torque is suppressed.

  6, 7, and 8 are diagrams showing a rotation angle and a state of magnetization, FIGS. 6A and 6C are plan views, FIG. 6B is a side view, and FIGS. FIG. 8A is a plan view, and FIG. 7B and FIG. 8B are side views. FIG. 6 shows an example in which the magnetization of the upper ring 2 shown in FIG. 6A and the lower ring 2 shown in FIG.

  As shown in FIG. 7, the magnetization may be performed by skew magnetization in which the magnetic poles are formed obliquely. Since the effect of the skew is limited to the notch 2a where the thickness of the ring magnet 1 is thin, the effect of reducing the cogging torque is sufficiently exhibited.

  Further, as shown in FIG. 8, even when so-called S-shaped skew magnetization is performed in which the skew angle changes in the axial position, the effect of reducing the cogging torque is sufficiently exhibited. The magnetization in FIG. 6 needs to be magnetized separately in the upper stage and the middle stage, but the skew magnetization in FIG. 7 can be magnetized once by using a magnetized yoke in which the coil is skewed. In the case of FIG. 8 as well, it is possible to magnetize at one time using a magnetizing yoke having a coil at a desired angle. Thus, this ring magnet can select the form which forms a magnetic pole as needed.

Embodiment 4 FIG.
FIG. 9 is a plan view (a) and a side view (b) showing Embodiment 4 of the sintered ring magnet according to the present invention, and FIG. 10 is a plan view showing the upper, middle and lower rings separately. It is figure (a), (c), (e) and side view (b), (d), (f).

  As shown in FIGS. 9 and 10, the ring magnet 1 includes two rings 2 and one ring 12 stacked in the axial direction and integrated by sintering, and each ring 2, 12 is radially oriented. The upper and lower ring 2 is formed with a notch 2a in which the outer periphery is cut out with a straight line, and the middle ring 12 is not formed with a notch. In this embodiment, the notch 2a serves as a boundary between the magnetic poles, and the magnetic pole is formed in the middle of the notch 2a. In the figure, a 6-pole ring magnet 1 is shown.

  As shown in FIG. 10, the ring 2 has the same shape in the axial direction, and the upper ring 2 (FIGS. 10 (a) and (b)) and the lower ring 2 (FIG. 10 (e), In (f)), the notches 2a are rotated by a predetermined rotation angle θ and are stacked via the ring 12 without notches.

  FIG. 11 is a plan view (a) and a side view (b) showing a state in which the ring magnet of this embodiment is magnetized. The upper ring 2 and the lower ring 2 are not skewed magnetic poles but form magnetic poles that do not rotate in the axial direction, and the middle ring 12 continuously connects the rotational deviations of the magnetic poles of the upper ring 2 and the lower ring 2. Yes.

  According to this embodiment, since the middle ring 12 is magnetized so as to connect the magnetic pole boundaries of the upper and lower rings 2, the magnetic poles can be formed with high accuracy by the upper and middle rings. it can.

  As can be seen from FIG. 4, the fundamental component of the magnetization distribution that contributes to the rotational torque of the motor is greatest when there is no notch (in the case of mb / mr = 1). For this reason, a larger torque can be obtained by the middle ring 12.

Embodiment 5 FIG.
FIG. 12 is a plan view (a) and a side view (b) showing a fifth embodiment of the sintered ring magnet according to the present invention.

  As shown in FIG. 12, the ring 2 in which the notch 2a is formed is arranged in the upper and lower stages, and the ring 12 in which the notch is not formed is arranged in the middle. In this embodiment, the length of the middle ring 12 is shortened.

  Thus, a larger torque can be generated by shortening the ring 2 having the notch portion 2a and lengthening the ring 12 without the notch portion.

Embodiment 6 FIG.
FIG. 13 is a plan view (a), (c) and a side view (b) showing a sixth embodiment of the sintered ring magnet according to the present invention.

  In this embodiment, as in the fifth embodiment, a ring 12 having no notch formed between the upper and lower rings 2 is arranged. However, as shown in FIG. The axial length of the ring 12 is shortened.

  The ring 12 is formed with skewed magnetic poles and connects rotational deviations of the magnetic poles of the upper and lower rings 2 and may be as short as possible within the allowable range for magnetization.

The skew angle θs in the ring 12 is equal to the rotation angle θ between the rings 2. When the axial length of the ring 12 is lr and the radius of the outer periphery of the ring magnet 1 is r, the following equation (1) is obtained.
lr> r × θs × tan θb (1)
Here, θb is an angle at which the magnetic pole boundary on the magnet surface is inclined with respect to the axial direction, and if θb <π / 4, there is little error in forming the magnetic pole by magnetization.
Therefore, the above formula (1) becomes the following formula (2), and the cogging torque can be reduced by defining the axial length lr within the range of the formula (2).
lr> r × θs (2)

Embodiment 7 FIG.
In the first to sixth embodiments, the case where the cogging torque corresponding to the least common multiple m of the number of magnetic poles of the ring magnet 1 of the rotor and the number of slots of the stator is canceled is shown. If the cogging torque corresponding to the least common multiple m is canceled out, cogging torque having a frequency that is twice that of the cogging torque may remain.

  FIG. 14 is a plan view (a) and a side view (b) showing a seventh embodiment of the sintered ring magnet according to the present invention. In FIG. 14, the pair of the first-stage ring 2 and the second-stage ring 2 is shifted by a rotation angle of 360/2 m [°], and the pair of the third-stage ring 2 and the fourth-stage ring 2 is the rotation angle. 360 / 2m [°] is off. Further, the pair of rings 2 of the first stage and the second stage and the pair of rings 2 of the third stage and the fourth stage are shifted by a rotation angle 360/4 m [°].

  FIG. 15 shows a case where the entirety is skew magnetized in this embodiment. In FIG. 15, the pair of the first-stage ring 2 and the third-stage ring 2 is shifted by a rotation angle of 360/2 m [°], and the pair of the second-stage ring 2 and the fourth-stage ring 2 is the rotation angle. 360 / 2m [°] is off. Further, the pair of the ring 2 of the first stage and the third stage and the pair of the ring 2 of the second stage and the fourth stage are shifted by a rotation angle of 360/4 m [°].

  According to this embodiment, it is possible to cancel the cogging torque corresponding to the least common multiple m, and further cancel the cogging torque of the doubled frequency.

  In this embodiment, a ring not having a notch may be provided between the steps.

  In addition, cogging torque of the number of magnetic poles of the rotor due to the stator and cogging torque of the number of status lots due to the ring magnet of the rotor may occur, but the rotation angle of each stage ring is set so as to cancel each of them. You can choose.

  The ring magnet of the present invention can be effectively used, for example, in a rotor of a rotating electrical machine. The motor of the present invention can be used for, for example, an elevator hoisting machine, an automobile electric motor, and the like.

It is the top view (a) and side view (b) which show the structure of the ring magnet in Embodiment 1 of this invention. It is the top view and side view which expand | deploy and show the ring of the ring magnet shown in FIG. It is the top view (a) and side view (b) which show Embodiment 2 of the sintered ring magnet which concerns on this invention. FIG. 6 is a diagram illustrating the relationship between the amplitude of the fundamental wave component of the magnetomotive force distribution and the amplitudes of the third, fifth and seventh harmonic components with respect to mb / mr. It is a block diagram which shows the cross section of the motor using the ring magnet of this invention. It is a top view (a), (c) and side view which show a rotation angle and the state magnetized. It is a top view (a), (c) and side view which show a rotation angle and the state magnetized. It is a top view (a), (c) and side view which show a rotation angle and the state magnetized. It is the top view (a) and side view (b) which show Embodiment 4 of the sintered ring magnet which concerns on this invention. It is the top view (a), (c), (e) and side view (b), (d), (f) which divided and showed the upper stage, interruption, and the lower stage ring. It is the top view (a) and side view (b) which show the state magnetized to the ring magnet of Embodiment 4. It is the top view (a) and side view (b) which show Embodiment 5 of the sintered ring magnet which concerns on this invention. It is the top view (a) which shows Embodiment 6 of the sintered ring magnet concerning this invention, (c), and a side view (b). It is the top view (a) which shows Embodiment 7 of the sintered ring magnet concerning this invention, (c), and a side view (b). In the seventh embodiment, the entire case is skew magnetized.

Explanation of symbols

1 ring magnet, 2,12 ring, 2a notch, 3 axis, 4 laminated core,
5 coils, 10 motors.

Claims (9)

In the manufacturing method of a sintered ring magnet in which a plurality of ring-shaped rings are stacked in the axial direction and integrated by sintering,
A step of individually forming a ring including at least two rings in which notch portions of the same shape extending in the axial direction on the outer circumferential surface thereof are periodically formed in the circumferential direction, and performing radial orientation;
The at least two rings formed with the notches are adjacent to each other, and the plurality of rings are arranged so that the positions of the notches are shifted from each other between the two adjacent rings at a predetermined rotation angle in the circumferential direction. The process of stacking,
Sintering the plurality of stacked rings;
A step of magnetizing the sintered ring so that the skew angle varies in the axial direction so that the notch becomes a boundary line of the magnetic pole in the ring in which the notch is formed. The manufacturing method of the sintered ring magnet characterized by these. 2. The rotation angle between the two adjacent rings in which the notch is formed is 360 / (2 × m) [°], where m is a multiple of 6. Manufacturing method for sintered ring magnets. 3. The method of manufacturing a sintered ring magnet according to claim 2 , wherein there are a plurality of sets of the two adjacent rings, and a rotation angle between the two adjacent rings is 360 / (4 × m) [°]. . 2. The sintered ring magnet according to claim 1, wherein the width of the notch portion is about 2/5 of the central angle of one magnetic pole portion when expressed by a central angle centered on the axis . Production method. The method for manufacturing a sintered ring magnet according to claim 4, wherein a radial thickness of the notch is about ½ of a radial thickness of the magnetic pole . In a sintered ring magnet in which a plurality of ring-shaped rings are stacked in the axial direction and integrated by sintering,
A plurality of the rings are formed with notches of the same shape extending in the axial direction on the outer peripheral surface thereof periodically in the circumferential direction,
The positions of the notches are stacked at a predetermined rotational angle in the circumferential direction between two adjacent rings formed with the notches,
A ring in which the notch is not formed is disposed between two adjacent rings in which the notch is formed;
In each ring in which the notch is formed , the center line parallel to the axial direction of the notch is a boundary line of the magnetic pole, and in the ring in which the notch is not formed, the boundary line of the magnetic pole The sintered ring magnet is magnetized so as to be skewed with respect to the axial direction . The following formula (1) is satisfied, where lr is the axial length of the cylindrical ring, r is the rotation angle θs, and r is 1/2 of the outer diameter of the ring. Sintered ring magnet.
lr> r × θs (1) A motor using the sintered ring magnet according to claim 6 for a rotor. In the manufacturing method of a sintered ring magnet in which a plurality of ring-shaped rings are stacked in the axial direction and integrated by sintering,
A ring including at least two rings in which notch portions of the same shape extending in the axial direction on the outer peripheral surface are periodically formed in the circumferential direction and at least one ring in which the notch portions are not formed. Individually molding and radial orientation;
The at least two rings formed with the notches are adjacent to each other, and the positions of the notches are shifted from each other between the two adjacent rings by a predetermined rotation angle in the circumferential direction. Stacking the plurality of rings such that a ring in which the notch is not formed is disposed;
Sintering the plurality of stacked rings;
In the ring in which the notch is formed, the center line parallel to the axial direction of the notch is the boundary line of the magnetic pole, and in the ring in which the notch is not formed, the boundary line of the magnetic pole is And a step of magnetizing so as to be skewed with respect to the axial direction.

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