JPH05176509A - Rotary electric machine - Google Patents

Abstract

PURPOSE:To reduce cogging torque without increasing a manufacturing cost, lowering output and generating demagnetization and to make it possible to reduce oscillations and noises. CONSTITUTION:A dc motor is constituted of a stator including two circular anisotropic magnets 10 and 12 and a rotor 14 including cores 16 and coils 18. The centers and vicinities of the anisotropic magnets 10 and 12 are oriented along radial and are oriented to the parallel orientation with the approach to the end. R is built up on the rotor 14 side of the end. The partial increment of the thickness of an equivalent magnet by the parallel orientation of the end is prevented by building up R, and the variation in magnetic flux distribution between the magnet and the core 16 becomes smooth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary electric machine using a permanent magnet.

[0002]

2. Description of the Related Art A general rotating electric machine, such as a DC motor, rotates by providing a field magnet on the stator side and energizing an armature conductor placed in a magnetic flux generated by the field magnet. The child is spinning.

By the way, the attraction force acting between the field magnet of the DC motor and the core of the rotor changes abruptly depending on the rotation angle, so that cogging torque is generated. For example, considering the case where a rotor is provided between two arc-shaped field magnets, a large torque acts on the core when the rotor core is in a position facing one of the field magnets. To do. On the other hand, if the core is between the two field magnets,
The acting torque decreases sharply.

This cogging torque causes vibration and noise during the operation of the DC motor. for that reason,
The following measures (1) and (2) have been taken to reduce the vibrations caused by this cogging torque.

A so-called eccentric magnet is used which realizes a smooth change in magnetic flux density by thinning the end portion of the magnet to reduce the magnetic flux density.

A so-called skew magnet is used in which the magnetic flux density distribution is gradually shifted in the rotational direction from the axial direction of the rotor.

According to the above-mentioned method, the change of the magnetic flux density distribution becomes smooth, so that the rapid change of the torque can be prevented.

The radial anisotropic cylindrical magnet is magnetized by using the magnetizing device disclosed in Japanese Patent Application Laid-Open No. 63-260118. According to this method, a sinusoidal smooth magnetic flux distribution can be obtained.

[0009]

However, in the above-mentioned methods (1) and (2), the effective magnetic flux is sacrificed with respect to the rotational force, so that there is a problem that the maximum torque and the output are inevitably reduced. .. In addition, in the method of
Since the end portion of the magnet is made thin, there is a problem that demagnetization occurs due to the armature reaction.

Further, the method (1) has a problem that the magnetization control is difficult and that the torque is reduced in the insufficiently magnetized portion and the maximum torque is inevitably reduced, resulting in a reduction in output. .. In addition, demagnetization cannot be avoided because it is not sufficiently magnetized.

In addition, it is possible to use rubber or the like for the bracket portion of the motor, but in this case, the cost is increased due to the addition of parts, and this is not an effective countermeasure.

In addition to this, as shown in FIG. 6, the central portion of the magnet 2 of the DC motor has a radial orientation 100, and a parallel orientation 110 as it approaches the end portions to smooth the change in magnetic flux density. It is also possible to take measures against vibration and the like. In this case, since the equivalent magnet thickness of the parallel orientation portion becomes large, the magnetic flux density distribution is partially disturbed (repulsion occurs) only by manipulating the orientation state, which is not a sufficient countermeasure. That is, if the vicinity of the end of the magnet 2 is parallel oriented 110,
The magnetic flux 110A from the yoke-side corner portion 2A of the magnet 2 shown by the diagonal lines in FIG.
0A is concentrated near the rotor side corner of the magnet 2 where the air gap between the magnet 2 and the rotor core 4 is small. As a result, the equivalent magnet thickness in the vicinity of the rotor-side corner of the magnet 2 is partially larger than the actual thickness d ₁ , and the magnetic lines of force flowing from this portion into the rotor core 4 are increased. As indicated by the arrow A, the magnetic flux density of the DC motor partly jumps up.

The present invention has been made in view of the above points, and it is possible to reduce the cogging torque, the vibration and the noise without increasing the manufacturing cost, reducing the output and demagnetizing. An object is to provide a rotating electric machine.

[0014]

In order to solve the above-mentioned problems, a rotating electric machine of the present invention is a rotating electric machine in which an anisotropic magnet is provided on a stator side, and the anisotropic magnet is It is characterized in that the central portion is radially oriented, the end portions are oriented in parallel, and a cutout portion for suppressing magnetic flux from entering is formed at the end portion.

Here, the notch may be formed by chamfering a corner of the end of the anisotropic magnet on the rotor side with a curved surface or a flat surface. Further, the notch of the end of the anisotropic magnet may be formed. It may be formed by notching the corner on the yoke side.

[0016]

In the rotating electric machine of the present invention, the center of the anisotropic magnet provided on the stator side is in the radial orientation,
The ends are in parallel orientation. Therefore, the magnetic flux density gradually decreases as it approaches the end of the magnet.

Further, the anisotropic magnet has a notch formed at the end thereof for suppressing the wraparound of the magnetic flux, and the equivalent magnet thickness is partially increased by the parallel orientation of the end. Is preventing. Therefore, the equivalent magnet thickness is not increased locally and the magnetic flux density distribution of the entire magnet is not disturbed.

As described above, in the present invention, the anisotropic magnet has parallel orientations near the ends thereof, and the cutouts for suppressing the wraparound of the magnetic flux are formed. Can be prevented, a smooth magnetic flux density distribution can be obtained, and vibration and noise can be reduced due to a large decrease in cogging torque.

Further, since only the orientation and shape of the magnet are changed and the number of parts and the assembly process are not affected,
The manufacturing cost does not increase. Also, the volume near the end of the magnet is only slightly reduced, and there is almost no effect on the output.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a DC motor in one embodiment to which the rotary electric machine of the present invention is applied.

In the figure, anisotropic magnets 10 and 12 are
It is composed of an arc-shaped (roof-shaped) permanent magnet, and a rare earth magnet such as neodymium or a ferrite magnet is generally used. These anisotropic magnets are oriented in the radial direction (radial orientation) near the center of the arc shape, and are gradually displaced from the radial direction toward the ends (parallel orientation).
Has been done.

In FIG. 1, the arrows shown in the anisotropic magnets 10 and 12 indicate the orientation direction, that is, the direction of the magnetic force lines. Arrows A to E are the directions of magnetic lines near the center,
Heading to the center of the arc. Further, arrows F, G, H and arrows f, g, h are the directions of magnetic force lines near the ends, and F →
The direction becomes closer to the end as G → H or f → g → h, and the direction deviates from the center of the arc.

Anisotropic magnet 1 having such an orientation direction
Magnetization is performed with 0 and 12 incorporated in a DC motor or with a single magnet. This magnetization is caused by the anisotropic magnet 10,
12 is performed so that each part has a saturation magnetic flux density.

At the ends of the anisotropic magnets 10 and 12,
Notches 10A and 10B for suppressing the wraparound of magnetic flux are formed, and the parallel orientation of the ends prevents the equivalent magnet thickness from partially increasing. In the embodiment, the cutouts 10A and 12A are
The corners of the anisotropic magnets 10 and 12 on the rotor 14 side are formed so as to have a predetermined R (the chamfering of a curved surface is referred to as "R"). This R
Is preferably set in a range of 2 / 3d ≦ R ≦ d with respect to the radial thickness d of the anisotropic magnets 10 and 12, and more preferably set to R = d.

The rotor 14 includes a core 16 and the core 16
And a coil 18 wound around. In this example,
Components such as a brush that are not directly related to the description are omitted.

The yoke 20 includes two anisotropic magnets 10, 1
It forms a magnetic path between the two and is made of soft iron or the like.
Therefore, a magnetic circuit is formed by the yoke 20, the anisotropic magnets 10 and 12, and the core 16 of the rotor 14, and the coil 18 of the rotor 14 is energized, for example, as shown in FIG. Will be driven to rotate.

FIG. 2 is an enlarged view of the vicinity of the end of the anisotropic magnet 10. As shown in the figure, since the corner portion of the end of the anisotropic magnet 10 on the rotor 14 side is rounded, the equivalent magnet thickness in the vicinity of the corner portion is smaller than that in the case without R. ing. Therefore, the anisotropic magnets 10, 12
It is possible to reduce the rising of the magnetic flux density distribution near the ends, and particularly when R is made substantially equal to the thickness d of the anisotropic magnet 10, the magnet thickness in the parallel orientation direction at the corners d ₂ is approximately equal to the thickness d, that is,
It becomes equal to the other portions that are radially oriented, and the magnetic flux density distribution near the ends of the anisotropic magnet 10 can be better prevented from jumping up. Further, by attaching R, the anisotropic magnet 10 and the rotor 14 are attached to the portion with R.
Since the magnetic path length, that is, the magnetic resistance is increased by increasing the distance from the core 16 of the magnetic flux, it is possible to prevent the wraparound of the magnetic flux from concentrating on the corner portion. It is possible to prevent splashing.

In FIG. 2, the case where the magnetic flux flows from the anisotropic magnet 10 to the core 16 of the rotor 14 has been described as an example, but the same applies to the case where the magnetic flux flows from the core 16 to the anisotropic magnet 12. Is.

FIG. 3 shows the DC motor of this embodiment,
6 is an explanatory diagram of a gap magnetic flux density waveform between anisotropic magnets 10 and 12 and a core 16 of a rotor 14. FIG. Anisotropic magnet 10,1
Since R is attached near the end portion of 2, the magnetic flux density distribution does not particularly rise, and it is understood that it has a substantially sinusoidal shape. It can be clearly seen that the magnetic flux density near the ends is improved in comparison with the case where the ends of the magnet are simply oriented in parallel (FIG. 7).

FIG. 4 is an explanatory diagram showing a comparison of the cogging torque between the DC motor of this embodiment and the conventional product. The vertical axis represents the magnitude of the cogging torque, and it can be seen that according to the present embodiment, the cogging torque is reduced to about 1/4 as compared with the conventional product in which the ends of the magnets are simply oriented in parallel.

As described above, the central portions of the anisotropic magnets 10 and 12 have a radial orientation, and the orientation is gradually paralleled as they approach the end portions, and R is attached to the end portions, whereby the core 16 of the rotor 14 is made. The magnetic flux density distribution between and becomes smooth, and the cogging torque can be greatly reduced. As a result, vibration and noise of the DC motor can be reduced.

Further, as compared with the conventional field magnet, since only the ends of the anisotropic magnets 10 and 12 are rounded, there is almost no decrease in the magnet volume and the maximum is larger than that of the conventional product. There is almost no decrease in torque and output.

Further, the magnet thickness d ₂ of the end portions of the anisotropic magnets 10 and 12 marked with R in the parallel orientation direction.
Is the magnet thickness d in the radial orientation of the other part.
_Since it is almost equal to ₁ , demagnetization does not occur as in the case where vibration is taken by thinning the magnet end.

Furthermore, the orientation near the ends of the anisotropic magnets 10 and 12 is changed, and the shape near the ends is only slightly changed. No additional, etc. are required, and the manufacturing cost is almost unchanged.

The present invention is not limited to the above embodiment, but various modifications can be made within the scope of the gist of the present invention.

For example, in the above-described embodiment, the case where the ends of the anisotropic magnets 10 and 12 are rounded has been described, but the same effect can be obtained even when the ends are chamfered with a flat surface. it can. FIG. 5 is a diagram showing a partial configuration of another embodiment in which the end portion is chamfered with a flat surface. As shown in the figure, the point that the equivalent magnet thickness at the end becomes smaller due to the chamfering of the flat surface, and at the same time, the magnetic path length near the end becomes large,
It is exactly the same as when R is attached.

In addition to this, anisotropic magnets 10, 12
The notches 12A and 12B may be formed by notching the yoke side corners of the anisotropic magnets 10 and 12. 8 and 9
FIG. 6 is a diagram showing an example of this case.

That is, if only the parallel orientation 110 is set near the ends of the magnets 10 and 12, the magnetic flux 110 from the yoke side corner portions 10A and 10B shown by the dotted line in FIG.
As described above, the wraparound of A occurs and this causes a partial jump of the magnetic flux density of the DC motor. In the present embodiment, the yoke-side corner portions 10A and 10B are cut out to prevent the magnetic flux from wrapping around. As a result, even if the ends of the anisotropic magnets 10 and 12 are oriented in parallel, the equivalent magnet thickness of this part does not increase locally and the magnetic flux density distribution of the entire magnet is prevented from being disturbed. It

Here, the cutout portions 10A, 10
It is preferable that B is the same as the parallel orientation direction of the rotor-side corners x1 of the magnets 10 and 12, and the ends of the anisotropic magnets 10 and 12 are cut along a plane including the corners x1. In the figure, the inner diameters of the anisotropic magnets 10 and 12 are d ₁₀ , the outer diameter is d ₁₂ , and the magnet angle is θ.

As described above, the anisotropic magnets 10, 1
By cutting the end of 2 parallel to the parallel orientation direction and including the inner edge portion of the magnet, the jumping of the magnetic flux at the edge portion can be reduced and the cogging torque can be greatly reduced.

Moreover, since the volume near the end of the magnet is only slightly reduced and self-demagnetization is small, there is almost no decrease in motor output.

In each of the above-described embodiments, the case where the cogging torque of the motor is reduced to take measures against vibration and noise has been described, but the invention can be applied to a generator.

[0044]

As described above, according to the present invention, the parallel orientation is provided near the ends of the anisotropic magnet, and the notches for suppressing the wraparound of the magnetic flux are formed. An increase in equivalent magnet thickness can be prevented, a smooth magnetic flux density distribution can be obtained, and vibration and noise can be reduced due to a significant decrease in cogging torque.

Moreover, since only the orientation and shape of the magnet are changed and the number of parts and the assembly process are not affected,
It does not increase the manufacturing cost. Also, the volume near the end of the magnet is only slightly reduced, and there is almost no effect on the output.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a DC motor according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the vicinity of an end of the anisotropic magnet of the example.

FIG. 3 is an explanatory diagram of a change in magnetic flux density of the DC motor according to the embodiment.

FIG. 4 is an explanatory diagram showing a comparison of cogging torque between the DC motor of the embodiment and a conventional product.

FIG. 5 is a partial configuration diagram of another embodiment in which the chamfered shape of the end portion of the anisotropic magnet is changed.

FIG. 6 is a partial configuration diagram of a conventional example in which the ends of the field magnet are simply parallel-oriented.

FIG. 7 is an explanatory diagram of changes in magnetic flux density of the DC motor of FIG.

FIG. 8 is an explanatory diagram of another embodiment of the present invention.

9 is an explanatory diagram of an anisotropic magnet used in the embodiment of FIG.

[Explanation of symbols]

 10, 12 Anisotropic magnet 14 Rotor 16 Core 18 Coil 20 Yoke

Claims (4)

[Claims] 1. A rotating electric machine having an anisotropic magnet provided on the stator side, wherein the anisotropic magnet has a radial orientation at a central portion, parallel orientation at an end portion, and magnetic flux at an end portion. A rotating electric machine, characterized in that a cutout portion for curling is formed. 2. The rotating electric machine according to claim 1, wherein the notch is formed by chamfering a corner of the end of the anisotropic magnet on the rotor side with a curved surface. 3. The rotating electric machine according to claim 1, wherein the notch is formed by chamfering a corner of the end of the anisotropic magnet on the rotor side with a flat surface. 4. The rotating electric machine according to claim 1, wherein the cutout portion is formed by cutting out a corner of the end of the anisotropic magnet on the yoke side.