JPS63228951A - Segment magnet - Google Patents

Abstract

PURPOSE:To improve rotating properties and reduce lowering of effective flux quantity by forming axial both ends of a segment magnet into skew forms and by making an inner diameter part eccentric from an outer one. CONSTITUTION:In a DC motor equipped with a segment magnet 2, said segment magnet 2 is fastented to a stator yoke 1. A rotor 4 is fitted concentrically with the stator yoke 1 via bearings 3a, 3b. In the segment magnet 2, axial both ends 21, 22 are skewed, the center O2 of an inner diameter (radius r1) is eccentric from the center O1 of an outer diameter (radius R0), and all axial arbitrary sections are identical in the shape with each other. when the rotor 4 is driven in such constitution, a rise occurs gradually from ends of the segment magnet and its gentle and smooth approximate sinusoidal waveform can be obtained and uneven rotation can be decreased. Further, smooth rotating properties can be obtained even at the time of high speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stator 1 of a DC motor, and particularly to improvements in stator segments 1 to magnets.

[Prior Art] Conventionally, a stator for a DC motor generally uses a winding, and the winding requires a large number of parts and manufacturing processes, and also requires many man-hours. However, in recent years, these have been made into permanent magnets, and permanent segment magnets have been used for the stator.

For example, in the stator shown in FIG. 4, segment magnets 28 to 2d are fixed to the inner circumferential surface of the stator yoke 1, thereby reducing the manufacturing process L and greatly improving manufacturing efficiency L.
, the manufacturing man-hours have also been reduced.

[Problems to be solved by the invention] However, the segment magnet 2a of the inner and outer span cores in the ML
~ If only 2d is used, there will be large unevenness in one rotation, and the rotation will not be performed smoothly.What is the change in the magnetic flux density in the circumferential direction of the gap part when the rotor is driven? 11! If I determine,
For example, as shown in FIG. 5, there were problems such as the waveform being angular and not providing smooth rotation.

In addition, stators for DC motors must have rotational irregularities as small as possible in order to reduce noise and improve rotational performance.
The current situation is to skew the rotor or make the segment 1 to magnets eccentric.

However, if the rotor is skewed, the winding work is very troublesome, and it is also difficult to make the winding skew. In addition, there are problems in that just by making the cement 1 to the magnet (i 41 eccentric), sufficient noise reduction and rotatability cannot be achieved, and that the effective magnetic flux Q is reduced.

Therefore, it is an object of the present invention to improve the rotatability L and
It is an object of the present invention to provide a Cefmen 1-magnet in which the amount of effective magnetic flux decreases little.

[Means for Solving the Problems] The present invention provides a safety member 1-magnet in which a DC motor with low noise and good rotatability can be obtained by only changing the shape of the stator-side permanent magnet.

That is, in the present invention, by combining the shape of both ends of the segment magnet in the axial direction with a skew shape and the eccentricity of the inner diameter side, rotational unevenness can be significantly reduced compared to the conventional method. It is something. From such a segment shape, especially eccentricity on the inner diameter side /! As shown in Figure 3, the operating waveform has a smooth rise from the inflection point of the S pole, L, and a rounded sine wave shape at the center of each pole, providing smooth rotation. It is something.

Furthermore, when obtaining the same rotational unevenness, a higher value of effective magnetic flux can be obtained than in the conventional case where only eccentricity is performed or when only skew is performed.

In particular, when the axial length is L and the skew angle is O, L
Skew 11 (S is expressed as tanθ, where 0 is 5 to 30
Set L so that it is within the range of °, and eccentricity 1 △r 2
It is desirable to set it as the range of 30 mm.

[Function] Smooth rotation is achieved by the segment magnet of the present invention.
The reason for this is as follows.

First, by skewing both ends of the magnet in the axial direction, the rotational resistance when the rotor moves from one magnetic pole to the adjacent magnetic pole with the opposite polarity is reduced.
As the torque decreases L, the rotation near the inflection point becomes smoother.

However, if the magnet is simply made into a skewed shape, the gap magnetic flux density in the circumferential direction does not change, so the operating waveform cannot be improved.

Therefore, if the inner diameter part of this skew-shaped magnet is made eccentric as shown in Figure 2, the gap dimension between the rotor and the magnet will be
In the circumferential direction of L1, L decreases smoothly up to the center line ρ.
, increases smoothly after passing the center line. Since the gap magnetic flux density is inversely proportional to the gap size, it changes smoothly in the circumferential direction.

Therefore, according to the present invention, a substantially sinusoidal waveform as shown in FIG. 8 can be obtained due to these synergistic effects.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a DC motor using segment magnets according to an embodiment of the present invention. In this motor,
A segment magnet 2 shown in FIG. 2 is fixed to a stator yoke 1, and a rotor 4 is attached coaxially with the stator yoke 1- through bearings 3a and 3b.

FIG. 2 is a side view of the safety men 1 to the magnet according to an embodiment of the present invention. This segment magnet 2 has both axial ends 21
．． 22 is skewed, and the center 02 of the inner diameter (radius rj) is eccentric with respect to the center 01 of the outer diameter (radius R8). The cement 1 to the magnet all have the same shape in arbitrary cross sections in the axial direction. In the case of such a configuration, when the rotor 4 is driven, as shown in FIG. 3, the waveform gradually rises from the end of the segment magnet, and a gentle and smooth approximate sinusoidal waveform is obtained.
Rotation unevenness can be reduced. Furthermore, smooth rotation can be achieved even during high speed rotation.

The present inventor used Cefmen 1~ magnets of various shapes and dimensions to confirm through experiments how rotational unevenness and the amount of effective magnetic flux required to obtain a predetermined motor torque change with the shape and dimensions of the magnets. did.

The results are shown in FIGS. 6 and 7.

Here, the shapes of the magnets used were (A) one with eccentricity only (see Figure 8), (B) one with skewed ends in the axial direction and eccentricity with different axial cross sections. (See Figure 9), (C) Both ends in the axial direction are skewed, and the inner diameter part is eccentric so that the axial cross section is the same (first
There are three types (see Figure 0), all of which have R9 = 35.8m.
m, ri=28.5-68.55mm, Q=64m
By changing m, L, and eccentricity △r from 0 to 40 mm, (1
3), (C), the skew 1t is S = 11.6
mm.

From FIG. 6, it can be seen that in any magnet, as the amount of eccentricity increases, the rotational unevenness decreases, and furthermore, by skewing in addition to the eccentricity of the inner diameter portion, the rotational unevenness decreases. For example, in some types of DC motors, it is generally desirable to have smaller rotational irregularities, so the larger the amount of eccentricity, the better. However, as the amount of eccentricity increases, the amount of magnetic flux decreases, so if the amount of eccentricity is 30 mm or less. Good. However, if the amount of eccentricity L is too small, the effect will be small, so 2 mm or more is necessary. Further, as the skew becomes smaller, the effect on reducing rotational unevenness becomes less effective, so O needs to be 1-5 degrees or more.

If there is a large skew in f, the decrease in magnetic flux (t) will be large, and the effect ratio of reducing rotational unevenness will be small, so 0 is 30°.
It is necessary to do the following.

From the results in -1-, for example, 0.3kF for rotation 11
In order to set X-c■, in the sagmen 1 to magnet of the present invention,
Effective magnetic flux)■! , about 6% towards 1-
I know what I can do. This allows the motor torque to be increased and current consumption to be reduced. Therefore, the efficiency of the motor can be significantly improved.

[The effects of the invention have been explained above! ! I11 In the present invention, the following effects can be obtained by making the magnet shape into Sagmen 1 - Setamen in which both ends of the magnet in the axial direction are skewed and L, and the inner diameter part is eccentric. .

1) When the rotor rotates smoothly and the same effective magnetic flux is obtained, rotational unevenness can be suppressed to a small level.

2) There is no need to make the rotor into a skewed shape, and smooth rotation performance can be obtained without changing from the conventional one.

:3) Since the rotation speed is small and smooth rotation is obtained, it is possible to improve the control characteristics of a DC motor and expand the range of applications.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a DC motor using magnets for segment 1 according to the present invention, FIG. 2 is a side view showing an embodiment of the segment magnet according to the present invention, and FIG. 3 is a cross-sectional view of a DC motor using a segment magnet according to the present invention. Fig. 4 is a side view of a stator using conventional segment magnets, Fig. 5 is an operating waveform diagram of the stator shown in Fig. 4, and Fig. 6 shows the relationship between inner diameter eccentricity lit and uneven rotation. Figure 7 is a diagram showing the relationship between the amount of inner diameter eccentricity and the amount of effective magnetic flux, and Figures 8, 9, and 1
Figure 0 is a diagram showing the difference in the shape of segment magnets. 1: Stator yoke, 2.2a 2d: Sagmen 1~
Magnet, 3a, 3b: Bearing, 4: Rotor Fig. 1 Fig. 2

Claims (2)

[Claims] (1) In a segment magnet with an arc shape used in a DC motor, both ends in the axial direction are skewed with respect to the axial direction, and the center of the inner diameter is eccentric with respect to the center of the outer diameter. A segment magnet characterized by having the same cross-sectional shape in any cross section. (2) L when the axial length is L and the skew angle is θ
The skew amount S represented by tan θ is set so that θ is in the range of 5 to 30 degrees, and the eccentricity Δr is set to 2 to 30 degrees.
The segment magnet according to claim 1, wherein the segment magnet is set in a range of mm.