JPS62166757A - Field magnet - Google Patents

Abstract

PURPOSE:To reduce the cogging quantity by widely cutting out and removing the angles of four (4) corners of a circular arc field magnet using an anisotropic magnet and by making the above-mentioned field magnet rhombic. CONSTITUTION:The four (4) corners of a circular arc-shaped field magnet is cut out into a rhomboid as shown in the figure. Thus the magnetic waveform is as shown in the figure. Usually its characteristic is as given by a, and it is possible to make it b by controlling magnetization, but with greatly scattering results. Nevertheless, suppose the field magnet is shaped as above-mentioned, the magnetization can be implemented in full magnetization without the control of magnetization. Particularly, when the removing angle a is theta/4-theta/3 and m is theta/4-theta/3, a good result is obtainable and the cogging quantity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a field magnet for minimizing cogging and smoothing rotation in a rotating machine such as a DC motor.

BACKGROUND OF THE INVENTION In recent years, DC motors have been used as drive sources for mechanisms in all fields, and there has been an increasing demand for smaller size, higher performance, smoother rotation, and higher output.

An example of the above-mentioned conventional field magnet will be described below with reference to the drawings.

A cross-sectional view of an example of a permanent magnet type rotating machine is shown in FIGS. 5 and 7. In Figures 5 and 7,
A rotor 1 is composed of an armature core around which an armature winding is wound and a commutator, and is rotatably held by an end bracket via a bearing. A frame 2 holds the field magnets 3 and 4.

Conventionally, this type of rotating machine used a field magnet to generate a magnetic field, but it was used only to obtain rotational force, so a stronger magnet was used to generate a larger magnetic flux. A field magnet is used.

Problems to be Solved by the Invention However, with the above-mentioned configuration, it is impossible to achieve the important purpose of a motor, which is to rotate smoothly, because it merely obtains rotational force. Conventionally, in order to obtain a smooth rotational force, an isotropic ring magnet was used and the magnetization operation was performed to smooth the magnetization waveform and reduce cogging.

However, in the case of isotropic magnets, the magnetic force is weaker than that of anisotropic magnets, and for modern devices that require higher output, isotropic magnets are used because of their weaker magnetic force. This makes it difficult to recruit. Therefore, anisotropic magnets with stronger magnetic force have become necessary. However, anisotropic magnets are more difficult to magnetize than isotropic magnets, and conventionally, magnetization has been done in a way that weakens the magnetic force of the magnet, or as shown in Figures 7 and 8. (Magnetization has been done by making magnets with uneven thickness.

However, with the above method, the quality could not be stabilized due to variations in polishing and magnetization operations.

In order to reduce the variation in the magnetization operation in the former method of the above, the latter method can be performed by supplying magnetization energy of the full magnetization value without performing the magnetization operation. It is a magnet that has become a magnet. Even in this method, the influence of variations in internal diameter polishing cannot be ignored, and with the recent miniaturization of equipment, field magnets have also become smaller and thinner (
However, if it becomes too thin, there is a limit to the uneven thickness of the latter and it is impossible.

In particular, for uneven thickness, it is desirable to make the 0 dimension that causes uneven thickness as shown in Figure 7 as thick as possible. For example, if the maximum magnet thickness is
When the thickness is about 1 m to 1.5 mm, polishing becomes difficult due to the problem of the material of the magnet being ferrite, making it impossible to create uneven thickness and making it difficult to reduce cogging.

In view of the above problems, the present invention minimizes cogging by changing the shape of the field magnet and provides smooth rotation.

Means for Solving the Problems In order to solve the above-mentioned problems, the field magnet of the present invention has an arc-shaped field magnet using an anisotropic magnet, with the four corners thickened (
It has a structure in which it is cut out and removed to form a diamond shape.

Effect The present invention has the above-mentioned configuration, so that magnetization can be performed without performing a magnetization operation (full magnetization), and even in a thin magnet, it can be magnetized without uneven thickness (the same effect as uneven thickness). obtained,
Polishing is easy, and a magnet that rotates smoothly with little cogging can be easily obtained.

EXAMPLE Hereinafter, effects of an example of the present invention will be explained with reference to the drawings.

FIG. 1 shows an external view of a magnet shape in a first embodiment of the present invention. In FIG. 1, a rotor 1 is composed of an armature core around which an armature winding is wound and a commutator, and is held by an end bracket via a bearing. A frame 2 holds the field magnets 3 and 4. FIG. 2 shows a field magnet.

The details of the magnet configured as described above will be explained with reference to FIGS. 1 and 2.

FIG. 1 shows the relative relationship between the armature of the motor and the magnets. By cutting and removing the four corners of the magnet in FIG. 2, the magnetic waveform becomes as shown in FIG. 9. Usually a
Although it is possible to change the characteristic to b by performing a magnetization operation, there is a large amount of variation. Second
With the shape shown in the figure, full magnetization can be performed without any magnetization operation. In particular, the removal angle a is θ/4 to θ
Good effects can be obtained when /3 and m are set to e/4 to e/3, and the amount of cogging can be greatly reduced as shown in FIG.

It is especially effective for thin magnets that cannot be unevenly thickened.
Suitable for things with thickness of mm to 1.511+m that do not allow uneven thickness. This cutting and removing means can be molded using a mold, and polishing is sufficient in a normal process.

As described above, according to this embodiment, by cutting and removing the four corners of the magnet to form a diamond shape, the amount of cogging can be reduced and rotation can be made smoother.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows an external view of a magnet shape in a second embodiment of the present invention, and FIG. 4 shows a field magnet. The above structure is similar to that of the first embodiment, but the difference is that the field magnet is made into a 14-thick piece.

The details of the magnet shape configured as described above will be explained below.

The first embodiment is effective for magnets that cannot be expected to have uneven thickness, but the second embodiment is effective for magnets that can have uneven thickness. C in the diagram
There are effects like. In other words, in addition to the effects of the first embodiment, there is an effect of uneven thickness.

It is added.

Effects of the Invention As described above, the present invention reduces the amount of cogging and improves rotation by making the four corners of the magnet into a rhombus shape in an arc-shaped field magnet using an anisotropic magnet. You can get a smoothing effect.

[Brief explanation of drawings]

1 is a plan view of the first embodiment of the present invention, FIG. 2 is a perspective view of the magnet of FIG. 1, FIG. 3 is a plan view of the second embodiment of the invention, and FIG. 4 is a perspective view of the magnet of FIG. Figure 3 is a perspective view of the magnet, Figure 5 is a plan view of the conventional example, Figure 6 is a perspective view of the magnet in Figure 5, Figure 7 is a plan view of another conventional example, and Figure 8 is Figure 7. FIG. 9 is a diagram showing the magnetic flux distribution of the magnet, and FIG. 10 is a diagram showing changes in cogging. 2...Frame, 3, 4...Field magnet. Name of agent Patent attorney Toshiki Nakao 1 person Figure 1 1-11-7 Figure 2 Figure 31? J θ Figure 4 Figure 5 Figure 5, Figure 36 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] An arc-shaped field magnet using an anisotropic magnet fixed to a motor housing, in which the four corners of the magnet are largely cut off to form a diamond shape.