JP2008182825A - Manufacturing method of rotor in synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a rotor in a synchronous motor, which minimizes a fluctuation in magnetization of a magnet, and is excellent in a motor torque characteristic. <P>SOLUTION: The rotor 1 in the synchronous motor comprises: the magnet 2 disposed on a plane facing a stator, and having a shape with a nonuniform radial thickness; and a back yoke 3 having a polygonal plane contacting the magnet 2. In the manufacturing method of the rotor 1 in the synchronous motor, the back yoke 3 is disposed and fixed so as to shift a phase to a magnetic field applied from the outside and to magnetize the magnet 2 at a predetermined angle in the direction opposite to the rotational direction of the rotor 1, and the magnet 2 is magnetized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a rotor of a synchronous motor.

  To provide a permanent magnet motor that can increase the combined torque of the magnet torque and the reluctance torque and that can easily adjust the current phase to a region where the torque is large and enables high-efficiency driving. In a permanent magnet motor having a salient pole type rotor with a built-in coil, the armature winding of the armature winding with respect to the axis where the center of the field magnetic flux distribution by the permanent magnet and the center of the armature magnetomotive force are electrically shifted by π / 2 The rotor axis where the inductance is maximized is shifted to the opposite side to the rotation direction. Specifically, the orientation characteristics or magnetization direction of the permanent magnet of the rotor is determined by the salient pole iron core on the outer periphery of the permanent magnet. Shift to the rotational direction side from the geometric center axis, or to the salient pole core on the outer periphery of the permanent magnet of the rotor, circumferentially at the end on the rotational direction side when viewed from the geometric center of the salient pole core The magnetic flux to Permanent magnet motor or providing a gel gap or punched holes has been proposed (e.g., see Patent Document 1).

  In order to provide a low-cost, low-noise, low-noise permanent magnet rotary motor that is easy to assemble and has reduced cogging torque and reluctance torque pulsation, the permanent magnet rotary motor is a laminated rotor core. A rotor having six permanent magnets embedded therein and a stator arranged concentrically on the rotor via a rotation gap, and the rotor core has one layer of permanent magnet per magnetic pole on the center side of the rotor. It is embedded in six axially extending magnet insertion holes that are convex, and for each pole pair, the positional relationship between the salient poles of the rotor and the teeth of the stator is set at an appropriate angle in the circumferential direction, for example, the rotor A permanent magnet rotary motor has been proposed in which the axial direction is shifted by 10 ° (see, for example, Patent Document 2).

  On the other hand, in a synchronous motor using a rotor with a magnet arranged on the surface, in order to improve the output of the motor and to suppress the pulsation of the output torque, the shape of the magnet used for the rotor is changed. There is a configuration in which an unevenly shaped magnet having a thick magnetic pole center and a thin gap between the poles is arranged on the rotor surface. At this time, the back yoke may have a substantially polygonal shape in accordance with the number of poles of the rotor, instead of a circle in contact with the magnet.

  In this case, the gap between the stator and the stator as viewed from the back yoke becomes non-uniform, the gap increases near the magnetic pole center of the rotor, and the gap between the poles decreases. For this reason, when a magnetic field is applied to the rotor from the outer periphery, the magnetic flux tends to collect in a small portion of the gap between the magnetic poles, thereby generating a reluctance torque in the back yoke, although it is slight.

  In the case of such a rotor, when the magnet is magnetized, the center of the magnetic pole of the magnetizing yoke is aligned with the thick part of the magnet. However, since the magnetic circuit of the back yoke is the most unstable position, the direction of the torque generated in the back yoke at the time of magnetization differs depending on a slight difference in the position of the rotor. For this reason, if the rotor is not fixed firmly, the rotor rotates and variations in magnetization occur.

  Further, when a magnet having an uneven thickness is manufactured by injection molding or the like, an orientation magnetic field corresponding to the number of magnetic poles of the rotor is formed inside the mold. When the back yoke is inserted into this mold and molded integrally, the center of the magnetic pole must be installed so that the portion with the smallest outer diameter of the back yoke, that is, the portion with the thickest magnet faces each other. is there. For this reason, the magnetic circuit of the back yoke is the most unstable state as described above, and the direction of the reluctance torque received by the back yoke changes due to a slight difference in the installation position, making installation difficult and a great force for fixing the position. And the accuracy of the fixed position is also required.

As a synchronous motor, the reluctance torque generated during operation is small compared to the IPM rotor (permanent magnet embedded type) due to the thickness of the magnet, but the magnetic field during magnet magnetization and orientation molding is very high. Since it is large, a relatively large torque is generated even by a slight gap difference. In order to suppress variations in magnet magnetization and orientation, it is necessary to increase the positioning accuracy, and at the same time, it is necessary to firmly fix the rotor so that it does not rotate due to the reluctance torque generated in the back yoke. . For this purpose, there is a problem that the production facility becomes a large scale.
JP 11-98737 A JP 2000-316242 A

  The present invention has been made to solve the above-described problems, and provides a method of manufacturing a synchronous motor rotor that can minimize variations in magnet magnetization and has excellent motor torque characteristics. For the purpose.

  In the method for manufacturing a rotor of a synchronous motor according to the present invention, a magnet having an uneven thickness which is disposed on a surface facing a stator and has a nonuniform radial thickness, and a surface in contact with the magnet are substantially polygonal. In a method of manufacturing a rotor of a synchronous motor having a back yoke, a phase of the back yoke is shifted by a predetermined angle in a direction opposite to the rotation direction of the rotor with respect to a magnetic field applied from outside to magnetize the magnet. It is characterized in that the magnets are magnetized by disposing and fixing them.

  In the method for manufacturing a rotor of a synchronous motor according to the present invention, in the magnetization process, the rotor is arranged on the magnetizing yoke so that the phase of the back yoke is in the reverse direction of the rotation direction in advance. By fixing the direction of reluctance torque generated in the back yoke in one direction when applied, positioning accuracy can be improved, and the magnetization variation of the magnet can be minimized. In addition, the rotor magnetized in this way can always generate reluctance torque generated in the back yoke during the operation of the synchronous motor in the rotational direction, so that the motor torque can be improved.

Embodiment 1 FIG.
1 to 4 show the first embodiment. FIG. 1 is a sectional view of the rotor 1 of the synchronous motor. FIG. 2 is a sectional view of the rotor 1 and the magnetized yoke 4 of the synchronous motor. FIG. 4 is a diagram showing the positional relationship between the rotor 1 and the magnetizing yoke 4 of the synchronous motor, and FIG. 4 is a diagram showing the relationship between the amount of displacement between the rotor 1 and the magnetizing yoke 4 of the synchronous motor and the output torque of the synchronous motor. It is.

  FIG. 1 shows one magnetic pole pair of a rotor 1 (8 poles) of a synchronous motor. The back yoke 3 is substantially octagonal. The magnet 2 has a substantially octagonal uneven shape with the outer circumference being cylindrical and the inner circumference being the same shape as the back yoke 3.

  Magnetization of the magnet 2 is usually performed at a position where the center of the magnet magnetic pole is thick and between the poles is thin so that the distribution of the surface magnetic flux of one magnetic pole is symmetric. In the rotor 1 of the synchronous motor according to the present embodiment shown in FIG. 1, the magnetic poles are not symmetrical. The center of the magnetic pole is shifted in a counterclockwise direction from a position where the magnet shape is symmetric (magnet shape symmetry axis). In this case, the rotation direction of the rotor 1 of the synchronous motor is counterclockwise. That is, in the rotor 1 of the synchronous motor, the center of the magnetic pole is at a position shifted from the axis of symmetry of the magnet shape in the rotation direction (counterclockwise direction).

  As shown in FIG. 2, the position of the rotor 1 is shifted in the opposite direction to the rotation direction of the rotor 1. During magnetization, a magnetic field (applied magnetic field) is generated by passing a current through the winding 5 of the magnetized yoke 4. When this magnetic field is applied to the rotor 1, the magnetic flux is concentrated on the thin portion of the magnet 2 where the gap between the magnetized yoke 4 and the back yoke 3 of the rotor 1 is the smallest. A force is applied to the rotor 1 so that this thin portion moves to the magnetic pole center of the magnetized yoke 4.

  If the position of the rotor 1 is as shown in FIG. 3, the direction of the force applied to the rotor 1 is always opposite to the rotational direction.

  For this reason, since the direction of the force applied to the rotor 1 can be limited to one direction, the rotor 1 is firmly fixed by fixing the position of the rotor 1 with a detent or the like so as not to rotate in the direction in which the force is generated. There is no need to do it. Further, since the dimensions need only be managed in one direction, the position of the rotor 1 with little variation can be easily fixed.

  FIG. 4 shows the relationship between the position of the rotor 1, the deviation of magnetization, and the output torque of the synchronous motor. The horizontal axis shows the angle of shifting the rotor 1, and the vertical axis shows the torque generated by the same current. The position shift in the direction opposite to the rotation direction of the rotor 1 is indicated by a positive value, and the same direction is indicated by a negative value. It can be seen that the output torque of the synchronous motor is slightly increased by shifting the magnetization in the opposite direction of the rotor 1.

  Further, when shifting in the same direction, the decrease in generated torque increases according to the shifted angle. This is because the reluctance torque generated in the back yoke 3 slightly influences the output during motor operation. The reluctance torque in the same direction as the output torque acts by shifting the rotor 1 in the direction opposite to the rotation direction and magnetizing it. Moreover, the reluctance torque of a reverse direction acts by shifting and magnetizing in the same direction. Therefore, torque characteristics as shown in FIG. 4 are obtained.

  From the above, it is possible to obtain the rotor 1 of the synchronous motor with little manufacturing variation and good characteristics.

  Here, when the magnet 2 used for the rotor 1 is an isotropic magnet 2, the direction in which the magnet 2 is magnetized depends on the direction of the applied magnetic field, and thus is generated in the rotor 1 in the magnetization process. The force to be applied is only the reluctance torque generated by the back yoke 3 having a polygonal shape. Therefore, the above-mentioned means (the rotor 1 is magnetized so that the phase of the back yoke 3 is in the reverse direction of the rotation direction in advance). 4, the direction of reluctance torque generated in the back yoke 3 when a magnetizing magnetic field is applied is fixed in one direction), so that the rotor 1 having stable characteristics can be obtained.

  Further, when a rare earth-based material is used for the magnet 2, the thin magnet 2 is often used, so that the gap between the back yoke 3 and the magnetized yoke 4 becomes smaller, and the reluctance generated during magnetization is reduced. The effect of torque is increased. For this reason, by arranging the rotor 1 in the magnetizing yoke 4 in advance so that the phase of the back yoke 3 is in the reverse direction of the rotation direction, the back yoke 3 is generated in the back yoke 3 when a magnetizing magnetic field is applied. The effect of stabilizing the characteristics by fixing the direction of the reluctance torque in one direction can be obtained more greatly.

Embodiment 2. FIG.
5 and 6 are diagrams showing the second embodiment. FIG. 5 is a diagram showing the shapes of the rotor 1 and the magnetized yoke 4 and the positional relationship between them. FIG. 6 is a diagram showing the gap magnetic flux density distribution of the synchronous motor. It is.

  As shown in FIG. 5, the positional relationship between the rotor 1 and the magnetized yoke 4 is the same as that in the first embodiment. However, the shape of the magnetized yoke 4 is different. The magnetized yoke 4 has an asymmetric shape with respect to the center of the magnetic pole. In the case of the rotor 1 according to the first embodiment, the magnetic flux density distribution on the rotor surface obtained by magnetization is asymmetric in the shape of one magnetic pole, so the surface magnetic flux density distribution for one magnetic pole is also relative to the magnetic pole center. It becomes an asymmetric waveform. As a result, distortion occurs in the induced voltage generated in the stator winding of the synchronous motor, and torque pulsation during operation increases. For example, when low vibration and low noise are required as in a blower application, it is necessary to keep torque ripple small. Therefore, it is desirable that the magnetic flux density distribution on the rotor surface is also less distorted.

  For this reason, in this embodiment, as shown in FIG. 5, the magnetized yoke 4 has an asymmetric shape with respect to the center of the magnetic pole. Specifically, the gap between the magnetized yoke 4 and the rotor 1 is made asymmetric with respect to the center of the magnetic pole. With respect to the center of the magnetic pole, the gap enlarged portion 6 is formed by enlarging the gap on one side (right side in FIG. 5) of the magnetic pole.

  By making the shape of the magnetized yoke 4 asymmetrical, the magnetic flux density distribution on the surface is brought close to a symmetrical waveform as shown in FIG. In FIG. 6, the thin line represents the magnetic flux density when the magnetized yoke 4 has a symmetrical shape with respect to the center of the magnetic pole. The thick line represents the magnetic flux density when the magnetized yoke 4 has an asymmetric shape with respect to the center of the magnetic pole.

  As a result, asymmetric distortion of the surface magnetic flux density distribution of the rotor 1 can be suppressed, and an increase in vibration and noise of the synchronous motor can be suppressed.

Embodiment 3 FIG.
7 to 9 are diagrams showing the third embodiment. FIG. 7 is a sectional view showing the rotor 1 and the orientation mold 7 of the synchronous motor. FIG. 8 is a diagram showing the rotor 1 and the orientation mold 7 of the synchronous motor. FIG. 9 is a diagram showing the relationship between the positional deviation between the rotor 1 and the orientation mold 7 and the output torque of the synchronous motor.

  FIG. 7 shows one magnetic pole pair of the 8-pole rotor 1. The back yoke 3 is substantially octagonal, the outer periphery of the magnet 2 is cylindrical, and the inner peripheral surface is substantially octagonal. The back yoke 3 is disposed inside the mold, and the magnet 2 is injection molded on the outer periphery. When the magnet 2 is an anisotropic material, the magnet 2 is oriented according to the number of magnetic poles by forming a magnetic field inside the mold in accordance with the number of magnetic poles of the rotor 1.

  In order to form a magnetic field of this orientation, as shown in FIG. 7, an orientation die 7 having an orientation yoke 7b that forms a magnetic pole on the outer periphery of the rotor 1 and an orientation magnet 7a that generates magnetic flux is disposed. In FIG. 7, a permanent magnet is used as the orientation magnet 7a, but it may be replaced with an electromagnet.

  When a permanent magnet is used for the orientation magnet 7a, a magnetic field for orientation is always generated inside the orientation mold 7. Therefore, when the back yoke 3 is installed in the orientation mold 7, the position where the substantially octagonal apex of the back yoke 3 coincides with the center of the orientation yoke 7b is the most stable state for the magnetic circuit. However, since the magnetic pole center of the magnet 2 is actually formed so as to be thick, the apex of the back yoke 3 must be fixed so as to be positioned between the poles of the orientation magnetic field. This position is the most unstable position for the magnetic circuit, and the direction of the torque generated in the back yoke 3 changes due to a slight shift of the apex position, which is not stable.

  In the present embodiment, as shown in FIG. 8, the back yoke 3 is installed in a state in which the back yoke 3 is rotated by a predetermined angle in the direction opposite to the rotation direction of the rotor 1 with respect to the magnetic field inside the orientation mold 7. . As a result, the reluctance torque generated in the back yoke 3 inside the orientation mold 7 is always in the direction opposite to the rotation direction of the rotor 1.

  FIG. 9 shows the relationship between the installation position of the back yoke 3 during molding and the motor output of a synchronous motor using the rotor 1 molded in that state. The horizontal axis indicates the amount of deviation (alignment phase) of the back yoke 3 in angle (mechanical angle), and the vertical axis indicates the torque ratio (%) generated at the same current (reference is the alignment phase 0 [deg]). The angle shifted in the opposite direction to the rotation direction of the rotor 1 is shown as positive, and the angle shifted in the same direction is shown as negative.

  When the back yoke 3 is shifted in the direction opposite to the rotation direction of the rotor 1 and the back yoke 3 is installed, the torque is slightly increased. When the back yoke 3 is shifted in the forward direction, the torque decreases according to the angle. You can see that As in the first embodiment, this is affected by the reluctance torque generated in the back yoke 3, and the back yoke 3 is installed in the orientation mold 7 in a direction opposite to the rotation direction of the rotor 1. This is because the reluctance torque in the same direction as the output torque is obtained during motor operation.

  In the present embodiment, the output torque is most obtained when the phase shift is approximately 5 ° (opposite to the rotation direction of the rotor 1). This does not necessarily apply to all forms and shapes of the rotor 1, but depends on the shapes of the back yoke 3 and the magnet 2. However, it is common in that the same effect can be obtained by shifting the back yoke 3 in the direction opposite to the rotational direction and disposing it on the orientation mold 7.

  Here, when the magnet 2 used for the rotor 1 is a rare earth-based material, a thin ring shape is often used in order to reduce the use weight, and therefore, the gap between the orientation yoke 7b and the back yoke 3 of the rotor 1 is reduced. And the influence of the reluctance torque generated inside the alignment mold 7 is increased. By using this embodiment, it is possible to stably manufacture the rotor 1 having good characteristics even in such a case.

  Further, when the material of the back yoke 3 is made of a resin containing soft magnetic powder, the linear expansion coefficient is close to that of the magnet material to be injection-molded (plastic magnet), and stress applied to the magnet 2 due to temperature change can be alleviated. The magnet 2 can be made thin. For this reason, the gap between the back yoke 3 and the alignment yoke 7b is reduced, and the reluctance torque inside the alignment die 7 is increased. According to the present embodiment, even in such a case, the rotor 1 having good characteristics can be stably manufactured.

Embodiment 4 FIG.
FIGS. 6 and 10 are diagrams showing the fourth embodiment, FIG. 6 is a diagram showing a gap magnetic flux density distribution of the synchronous motor, and FIG. 10 is a cross-sectional view showing the rotor 1 and the orientation die 7 of the synchronous motor. .

  The positional relationship between the alignment yoke 7b and the rotor 1 inside the alignment mold 7 is the same as that in the third embodiment, but the shape of the alignment yoke 7b is different. The orientation yoke 7b has an asymmetric shape with respect to the center of the magnetic pole. In the case of the rotor 1 according to the second embodiment, the magnetic flux density distribution on the rotor surface obtained by orientation is asymmetric with respect to the shape of one magnetic pole, so the distribution of surface magnetic flux density for one magnetic pole is also asymmetric with respect to the magnetic pole center. Waveform. As a result, distortion occurs in the induced voltage generated in the stator winding of the synchronous motor, and torque pulsation during operation increases. When low vibration and low noise are required as in blower applications, it is necessary to keep the torque ripple small. Therefore, it is desirable that the magnetic flux density distribution on the rotor surface has less distortion.

  For this reason, in this embodiment, as shown in FIG. 10, the shape of the orientation yoke 7b is made asymmetric. Specifically, the gap between the orientation yoke 7b and the rotor 1 is made asymmetric with respect to the center of the magnetic pole. The gap enlargement portion 6 is formed by enlarging the gap on one side (right side in FIG. 10) of the magnetic pole with respect to the center of the magnetic pole. Thereby, the magnetic flux density distribution on the rotor surface can be brought close to a symmetrical waveform as shown in FIG. As a result, asymmetric distortion of the surface magnetic flux density distribution of the rotor 1 can be suppressed, and an increase in vibration and noise of the synchronous motor can be suppressed.

  As an application example of the present invention, the present invention can be applied to an air conditioner and a synchronous motor used for a blower, which often use a rotor having a magnet disposed on the surface.

FIG. 3 shows the first embodiment and is a cross-sectional view of the rotor 1 of the synchronous motor. FIG. 3 is a diagram showing the first embodiment, and is a cross-sectional view showing a rotor 1 and a magnetized yoke 4 of the synchronous motor. FIG. 3 shows the first embodiment and shows the positional relationship between the rotor 1 and the magnetized yoke 4 of the synchronous motor. FIG. 3 is a diagram illustrating the first embodiment, and is a diagram illustrating a relationship between a displacement amount between the rotor 1 and the magnetizing yoke 4 of the synchronous motor and an output torque of the synchronous motor. FIG. 6 is a diagram showing the second embodiment, and shows the shape of the rotor 1 and the magnetized yoke 4 and the positional relationship between them. The figure which shows Embodiment 2, 4, and is a figure which shows gap magnetic flux density distribution of a synchronous motor. FIG. 6 is a diagram showing a third embodiment, and is a cross-sectional view showing a rotor 1 and an orientation mold 7 of a synchronous motor. FIG. 10 is a diagram illustrating the third embodiment and is a diagram illustrating a positional relationship between the rotor 1 of the synchronous motor and the orientation mold 7. FIG. 9 is a diagram illustrating the third embodiment, and is a diagram illustrating a relationship between a positional deviation between the rotor 1 and the orientation mold 7 and an output torque of the synchronous motor. FIG. 10 is a diagram showing the fourth embodiment, and is a cross-sectional view showing a rotor 1 and an orientation mold 7 of a synchronous motor.

Explanation of symbols

  1 rotor, 2 magnets, 3 back yoke, 4 magnetized yoke, 5 windings, 6 gap enlarged portion, 7 orientation mold, 7a orientation magnet, 7b orientation yoke.

Claims (8)

In a method for manufacturing a rotor of a synchronous motor, which is arranged on a surface facing a stator and has a magnet having an uneven thickness with a nonuniform radial thickness and a back yoke having a substantially polygonal surface in contact with the magnet ,
The magnet is magnetized by arranging and fixing the back yoke by shifting the phase by a predetermined angle in the direction opposite to the rotation direction of the rotor with respect to the magnetic field applied from outside to magnetize the magnet. A method for manufacturing a rotor of a synchronous motor, characterized in that:   The distribution waveform for one magnetic pole of the applied magnetic field used for magnetizing the magnet is asymmetric with respect to the center of the magnetic pole so that the surface magnetic flux density distribution of the magnetized rotor is symmetrical with respect to the magnetic pole center. The method for manufacturing a rotor of a synchronous motor according to claim 1, wherein:   3. The method of manufacturing a rotor of a synchronous motor according to claim 1, wherein an isotropic magnet is used as the magnet. In a method for manufacturing a rotor of a synchronous motor, which is arranged on a surface facing a stator and has a magnet having an uneven thickness with a nonuniform radial thickness and a back yoke having a substantially polygonal surface in contact with the magnet ,
The magnet is formed by arranging and fixing the back yoke by shifting the phase by a predetermined angle in the direction opposite to the rotation direction of the rotor with respect to the magnetic field applied from the outside in order to form and orient the magnet. A method for manufacturing a rotor of a synchronous motor, characterized in that:   The distribution waveform for one magnetic pole of the magnetic field inside the orientation mold used for orientation of the magnet is set so that the surface magnetic flux density distribution of the rotor on which the magnet is oriented is symmetrical with respect to the magnetic pole center. The method for manufacturing a rotor of a synchronous motor according to claim 4, wherein the rotor is asymmetric with respect to the left and right.   6. The method for manufacturing a rotor of a synchronous motor according to claim 4, wherein an anisotropic magnet is used as the magnet.   7. The method of manufacturing a rotor of a synchronous motor according to claim 1, wherein a rare earth magnet is used as the magnet.   The method for manufacturing a rotor of a synchronous motor according to any one of claims 1 to 6, wherein a material obtained by mixing soft magnetic powder and resin is used for the back yoke.

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