JPH05168209A - Direct current machine - Google Patents

Abstract

PURPOSE:To attenuate oscillation and noise by attenuating ripple torque, without increasing a manufacturing cost and lowering output. CONSTITUTION:A DC motor is composed of an armature 14 including two circular anisotropic magnets 10, 12, a core 16, and an armature conductor 18, and a yoke 20. The anisotropic magnets 10, 12 are the permanent magnets of ferritic magnets, neodymium magnets, or the like, and in the consideration of armature reaction in the process of orientation, the center of poles is oriented to be positionally shifted from the center of the magnets by the angle theta of armature reaction component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC 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, when a current flows through the armature conductor,
This armature current generates a magnetic flux, which affects the distribution and strength of the main magnetic flux (magnetic flux generated by the field magnet). When the main magnetic flux is distorted due to the demagnetization effect caused by such armature reaction, ripple torque (torque unevenness) is generated in the output of the DC motor, and this ripple torque causes vibration and noise of the DC motor. There is. Therefore, in order to reduce the vibration and the like due to the ripple torque, various measures shown in and are taken.

The brushes are arranged so as to be displaced in the direction opposite to the rotation direction of the motor by the armature reaction amount, and the energization timing is shifted. This reduces abrupt changes in magnetic flux at the magnet ends, and prevents abrupt changes in torque.

A radial anisotropic cylindrical magnet is magnetized by using the magnetizing device disclosed in Japanese Patent Laid-Open No. 63-260118. According to this method, it is possible to obtain a sinusoidal smooth magnetic flux distribution, and as a result, it is possible to reduce ripple torque and vibration and noise.

[0006]

By the way, in the above-mentioned method, abrupt torque fluctuation can be prevented by shifting the electrically neutral axis, but there is a point that the field magnetic flux distribution is distorted by the demagnetization effect. It has not been particularly improved and cannot be said to be an effective means. Further, since the energization timing is shifted, the field magnetic flux is reduced, and moreover, the magnetic flux effective for the basic rotational force is sacrificed, so that there is a problem that the reduction in output cannot be avoided. Furthermore, how much the electrical neutral axis shifts depends on the shape of the armature conductor and the magnitude of the rated current that flows through it, so equipment is required for each motor specification, which increases the manufacturing cost of the motor. There was a problem.

Further, in the method (1), since the magnetized portions and the non-magnetized portions are alternately and appear in a sinusoidal shape, it is possible to prevent a rapid change in torque. However, there is a problem in that the torque is reduced in the non-magnetized portion, the original performance of the magnet is not fully utilized, and a reduction in output cannot be avoided. Further, even if the magnetic flux has a sine wave shape, it is still affected by the armature reaction, so that the ripple torque is still generated.

Therefore, the above-mentioned methods (1) and (2) are insufficient as a measure for reducing vibration and noise, and an effective measure has been desired.

The present invention has been made in view of the above circumstances, and provides a DC machine capable of reducing the ripple torque and the vibration and noise without increasing the manufacturing cost and reducing the output. The purpose is to provide.

[0010]

In order to solve the above-mentioned problems, the present invention is a DC machine using an anisotropic magnet as a magnetic pole of a stator, wherein the anisotropic magnet is effective for armature reaction. It is characterized in that the orientation is performed by shifting the magnetic pole center in the direction opposite to the direction of movement of the resulting electrically neutral axis, and is magnetized.

Here, when the movement angle of the electrical neutral axis caused by the armature reaction generated when a rated current is applied to the armature is θ, the anisotropic magnet is
A portion deviated from the mechanical center of the magnet by an angle of −θ is formed as a magnetic pole center that is radially oriented toward the rotation axis,
It is preferable to orient toward a direction that is sequentially displaced from the rotation axis as the distance from the magnetic pole center increases.

When the present invention is applied to a DC motor, it is necessary that the anisotropic magnet is formed so that the magnetic pole center is displaced in the same direction as the rotation direction.

When the present invention is applied to a DC generator, the anisotropic magnet must be formed so that the magnetic pole center is displaced in the direction opposite to the rotation direction.

[0014]

In the direct current machine of the present invention, when determining the orientation of the anisotropic magnet provided on the stator side, the center of the magnetic pole is shifted in consideration of the armature reaction component in advance and the orientation is set. Magnetize. When a rated current is applied to the armature, the magnetic flux created by this current is combined with the main magnetic flux created by the anisotropic magnet to form a field magnetic flux, and the center of this field magnetic flux distribution almost coincides with the center of the magnet. To do. Therefore, the ripple torque is reduced.

Further, the magnet can be magnetized so as to cancel the cross electromotive force due to the armature reaction, and the decrease in output can be reduced.

Further, it becomes unnecessary to take measures such as shifting the position of the brush according to the specifications of each DC machine, and the manufacturing cost is not increased.

As described above, in the present invention, the orientation is performed in consideration of the armature reaction, whereby the manufacturing cost is not increased, the ripple torque is reduced without the output reduction, and the vibration and the noise are reduced. It is possible to provide a DC machine capable of performing the above.

[0018]

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

FIG. 1 shows the configuration of a DC motor in an embodiment to which the DC machine of the present invention is applied.

In the figure, the anisotropic magnets 10 and 12 are
It is composed of an arc-shaped permanent magnet, and generally, a ferrite magnet, a neodymium magnet, or the like is used. These anisotropic magnets 10 and 12 consider the magnetic flux of the armature reaction in the process of determining the orientation. Specifically, the anisotropic magnets 10 and 12 are magnetized by being oriented with the magnetic pole centers displaced in a direction opposite to the moving direction of the electrical neutral axis caused by the armature reaction. Characterize.

Here, when the moving angle of the electrical neutral axis caused by the cross electromotive force generated when a rated current is passed through the armature conductor 18 is θ, the anisotropic magnets 10 and 12 are A portion of the magnet that is deviated from the mechanical center axis 100 by an angle of −θ is formed as a magnetic pole center 110 that is radially oriented toward the rotation axis, and as the distance from the magnetic pole center 110 increases, the direction gradually deviates from the rotation axis. Orient.

When the DC machine is a motor, the movement of the electrically neutral shaft is in the direction opposite to the rotation direction of the rotor,
When the DC machine is a generator, it moves in the same direction as the rotation direction of the rotor.

Therefore, when the present invention is applied to a DC motor as in this embodiment, the anisotropic magnets 10,
The magnetic pole center 110 of 12 is formed so as to be displaced from the mechanical center axis 100 of the magnet in the same direction as the rotor rotation direction. still,
When the present invention is applied to a generator, the magnetic pole center 110
May be formed so as to be displaced in the direction opposite to the rotation direction.

Next, the orientation structure of the anisotropic magnets 10 and 12 of the embodiment will be specifically described.

The portions of the anisotropic magnets 10 and 12 that are deviated from the symmetry axes 100 (mechanical center axes of the magnets) 100 in the rotational direction are oriented toward the rotational axis, and the other portions are oriented. By sequentially orienting in a direction deviating from the rotation axis, the center 110 of the magnetic pole is displaced in the rotation direction by an angle θ corresponding to the armature reaction. Figure 1
The arrow A shown in (1) indicates the direction of the magnetic force line at a portion deviated from the center 110 of the magnetic pole in the rotation direction by the armature reaction amount θ, and is directed toward the rotor rotation axis (the center of the armature 14 described later). Further, arrows B to G indicate the directions of magnetic lines of force other than the center 110 of the magnetic pole. The arrow B in the vicinity of the arrow A points in a direction slightly deviated from the rotation axis, and the deviation from the rotation axis increases as the arrows C, D, ... Note that the orientation is similarly performed in the rotation direction as viewed from the position of the arrow A, but the vicinity of the end portion (arrow H) is parallel orientation instead of radial orientation. This makes it possible to prevent a rapid change in torque.

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. The magnetization is performed so that each part of the anisotropic magnets 10 and 12 has a saturation magnetic flux density.

The armature 14 includes a core 16 and the core 16
And an armature conductor 18 wound around.

The yoke 20 includes two anisotropic magnets 10 and 1.
2 magnetic paths are formed and are made of soft iron or the like. Therefore, the yoke 20, the anisotropic magnets 10 and 12, and the core 16 of the armature 14 form a magnetic circuit.
The armature 14 is driven to rotate by energizing the armature conductor 18 of No. 4 as shown in FIG. 1, for example.

Next, the operation of the DC motor of this embodiment will be described.

The DC motor of the present invention has the anisotropic magnet 1 that generates the main magnetic flux when the armature conductor 18 is not energized.
The center 110 of the 0 and 12 magnetic poles is an arc-shaped target shaft 100.
From the angle θ.

Therefore, when a rated current is applied to the armature conductor 18 in the direction shown in FIG. 1, a force acts counterclockwise to rotate the armature 14. At this time, the anisotropic magnets 10 and 12
When the magnetic field is radially oriented as in the conventional case, the field magnetic flux is a combination of the main magnetic flux generated by the anisotropic magnets 10 and 12 and the cross magnetic force generated by passing a current through the armature conductor 18. The center of the distribution deviates from the central axis 100 of the anisotropic magnets 10 and 12 by θ in the direction opposite to the armature rotation direction,
This was the cause of the ripple torque.

On the other hand, in this embodiment, the anisotropic magnet 1 is used.
For the center 100 of the magnets 0 and 12, its magnetic pole center 11
0 is formed so as to deviate by an angle θ in the rotation direction of the armature 14. Therefore, even if a cross magnetomotive force is generated when a rated current is applied to the armature conductor 18, the anisotropic magnets 10, 1
The center axis of the field magnetic flux distribution obtained by combining the main magnetic flux 2 and the cross electromotive force is substantially coincident with the center 100 of the magnets 10, 12.

As a result, a sinusoidal field magnetic flux density distribution can be obtained when the motor is driven, high- and long-wave components contained in the torque during operation can be reduced, and smooth rotation can be obtained. Therefore, according to the DC motor of this embodiment, it is possible to reduce torque ripple and vibration and noise.

FIG. 2 shows the torque waveform of the DC motor of this embodiment. A is the torque waveform of the DC motor of this embodiment, and B is the torque waveform of the DC motor when a radial anisotropic magnet is used. Conventionally, as shown in B, the magnetic flux distribution is distorted by the armature reaction, and the torque waveform thereof contains harmonic components. On the other hand, in the DC motor of this embodiment, the influence of the armature reaction is reduced by the magnets 10 and 12.
Since the torque waveform is taken into consideration when the motor is oriented, the torque waveform has only a first-order component that does not include harmonic components when the motor rotates.

Incidentally, C shows the case where the torque waveform is adjusted by changing the energization timing, and it is shown that although the harmonic component can be removed, the maximum torque also decreases at the same time. Therefore, it is obvious that the method of changing the energization timing is not an effective means because it can reduce the vibration and the like but also reduces the output.

FIG. 3 shows a comparison of vibration levels of the DC motor of this embodiment and a conventional DC motor. The result of measuring vibration with the same torque and the same number of revolutions is shown, and the vertical axis represents the vibration level. As shown in the figure, the vibration level of the DC motor of the present embodiment is about one fifth of that of the DC motor using the conventional radial anisotropic magnet, and the vibration level of the DC motor with the conventional energization timing changed. About 1/3 to 4
It can be reduced by a factor of one.

As described above, in this embodiment, the armature conductor 18 is energized by orienting the anisotropic magnets 10 and 12 by shifting the center 110 of the magnetic pole by the angle θ in consideration of the armature reaction. The center of the magnetic field flux distribution is made to coincide with the centers of the anisotropic magnets 10 and 12 when the DC motor is rotated by rotating the DC motor. As a result, the generation of ripple torque can be prevented and the torque waveform of only the primary component can be obtained, so that vibration and noise during rotation can be reduced.

Further, unlike the case where the energization timing is changed, a manufacturing facility for each specification is not required, and the manufacturing cost does not increase due to measures against vibration.

Furthermore, the maximum torque does not decrease, and it is possible to prevent the output from decreasing when countermeasures against vibration are taken.

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

For example, although the above-mentioned embodiment has explained the case of taking measures against vibration and noise of the DC motor, it can be applied to a DC generator.

In this embodiment, the case where the two arc-shaped anisotropic magnets 10 and 12 are used has been described. However, when the stator is formed using a circular magnet, or three or more magnets are used. The same can be applied to the case.

[0043]

As described above, according to the present invention, the orientation of the magnet is taken into consideration in consideration of the armature reaction, so that the distortion of the field magnetic flux density distribution during operation can be compensated, so that the manufacturing cost is increased. In addition, the ripple torque can be reduced without lowering the output, and vibration and noise can be reduced.

[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 an explanatory diagram of a torque waveform of the DC motor according to the embodiment.

FIG. 3 is an explanatory diagram of a vibration level of the DC motor according to the embodiment.

[Explanation of symbols]

 10, 12 Anisotropic magnet 14 Armature 16 Core 18 Armature conductor 20 Yoke

Claims (4)

[Claims] 1. A direct current machine using an anisotropic magnet as a magnetic pole of a stator, wherein the anisotropic magnet has a magnetic pole center in a direction opposite to a moving direction of an electrical neutral axis caused by an armature reaction. A direct current machine characterized by being magnetized by shifting the orientation. 2. The anisotropic magnet according to claim 1, wherein the moving angle of the electrical neutral axis caused by an armature reaction generated when a rated current is applied to the armature is θ. The part deviated from the mechanical center of -θ by an angle of -θ is formed as the magnetic pole center that is radially oriented toward the rotation axis, and as the distance from the magnetic pole center is increased, the orientation is sequentially shifted from the rotation axis. Characteristic DC machine. 3. The DC motor according to claim 1 or 2, wherein the anisotropic magnet shifts a magnetic pole center in the same direction as the rotation direction. 4. The DC generator according to claim 1 or 2, wherein the anisotropic magnet shifts a magnetic pole center in a direction opposite to a rotation direction.