JP3134574U - Speed control of small DC motor by field magnet. - Google Patents

Abstract

It is possible to increase / decrease the rotational speed of a small DC motor by using a field magnet, not in a Hall element or other electronic components.
The field magnet is made into two sets of arc-shaped field magnet pairs, and the speed of the motor can be controlled by manually moving the pair of field magnet pairs. Moreover, in a large-sized field magnet, it becomes possible by dividing a field magnet into a plurality of U-shaped magnets.
[Selection] Figure 5

Description

The present invention relates to speed control of a small DC motor using a plurality of field magnets.

The rotational speed of the small DC commutator type motor can be controlled through detection of a position by a magnetic sensor, a Hall element, a phototransistor or the like through an electronic circuit. Further, the rotor position can be detected with a commutator that also serves as a rotary switch, and the rotational speed can be controlled by increasing or decreasing the voltage.

However, in the rotational speed control by voltage control, a control circuit via a line drawn from the motor main body is required instead of the motor body.

Since a control circuit is attached in addition to the motor, in a small model car, a model helicopter, etc., not only the motor but also a space for arranging the circuit is required. So it was a form without speed control. In particular, the rotation speed of the wing at the rear of the model helicopter could not be reduced. Or, there was no small electric fan that could control the speed in contact with the motor body.

As an improvement measure, there is a method in which the control circuit is pulled out and connected to the motor. However, it becomes an extra accessory and complicated.

The problem to be solved is to perform the rotational speed control without requiring the rotational speed control circuit.

The main feature of the present invention is that the rotational speed can be easily controlled because a plurality of field magnets can be used to change the magnetic flux group directed to the center of the rotor of the field magnet.

The field magnet group of the present invention can change the speed by manual operation on the field side, so there is no need for a wire with the control circuit, and the rotation speed of each motor according to the target rotation speed There is an advantage that it can be controlled.

The objective of changing the magnetic flux toward the rotor center of the field magnet was realized with a minimum number of parts and almost no loss of the size of the conventional small motor. In order to increase the scale of the motor, the field magnets are divided into U-shaped magnet groups.

A normal small DC commutator motor rotates the rotor 3 by soft iron yokes 2 extending from both magnetic poles of the U-shaped magnet 1 that are equidistant from the rotor.
However, by bringing one pole closer to the rotor 3 as shown in FIG. 1, an asymmetric magnetic field structure is obtained, and the rotation speed can be increased. Alternatively, the rotational speed can be reduced by returning to the conventional position.

Furthermore, the rotational speed can be changed by extending the yoke 2 beyond the rotor 3 and deforming the shape so that the yokes 2 come into contact with each other.

The rotational speed can also be increased by overlapping two U-shaped magnets with the same polarity.
The superposed U-shaped magnet may overlap the original magnet 1 and different poles, and the rotational speed is created by creating an asymmetric magnetic field in the rotor by moving the superposed magnet closer or further away, or by rotating it. Can be increased or decreased.

Furthermore, speed control can also be performed by arranging another U-shaped magnet between the yokes 2 on the opposite side of the rotor 3 with respect to the position of the U-shaped magnet 1. At this time, if one of the original magnetic poles is N, the magnetic pole of a new magnet in contact with the yoke extending through the rotor is also N.
Rotational speed control is performed based on the distance between the inclination of the U-shaped magnet newly disposed at the target position and the rotor. Alternatively, the speed can be controlled even if the magnetic pole of the newly arranged magnet is reversed by changing the number of poles of the rotor 3.

By developing the above, the following rotation speed control becomes possible.
In a normal small DC commutator type motor, only a constant rotational speed can be obtained by a pair of arc-shaped magnet pairs facing different poles. Therefore, as shown in FIG. 2, the bar magnets 4 are arranged so as to surround the rotor 3 (not shown in the figure) in a circumferential shape, and the magnetic flux directions of the inner poles of the magnets are arranged so as to face the center of the rotor. At this time, the inner side of the magnet on one semicircle of the bar magnet group 4 is an N pole, and the inner side of the magnet on the other semicircle is an S pole. The rotational speed can be increased or decreased depending on the number of the bar magnets 4 arranged.

However, the rotational speed of the bar magnet 4 is likely to be unstable due to the gap between the magnets. Therefore, as shown in FIG. 3, the U-shaped magnets 1 are arranged so that the inner magnetic poles are in contact with each other. This effectively increases the number of rotors 3 (omitted in the figure). However, the two places 5 where the different poles are adjacent to each other are separated by, for example, a plastic piece that is not a magnetic material. The outer magnetic pole is covered with the outer yoke 6 so as to surround all the poles.
Further, in order to examine whether or not the instability of the rotational speed is effectively reduced, the axis of the rotor 3 is fixed. This proves that the field side, that is, the field magnet group 1 starts to rotate smoothly.

The two arc magnet pairs used in a normal small DC commutator motor become larger as the motor becomes larger, so that the material becomes fragile and the magnetizing method becomes larger. However, these problems can be solved by arranging the U-shaped magnet 1 as shown in FIG.

Further, another magnet group 7 having a yoke on the outer periphery in the same arrangement as the magnet group 1 in FIG. 3 is arranged below the magnet group 1 in FIG. 3 as shown in FIG. The rotational speed can be increased or decreased by gradually rotating the lower small magnet group 7 in the circumferential direction.

Further, as shown in FIG. 5, two pairs of arc magnets 8 and 9 are arranged, and the rotation speed can be increased or decreased by rotating the lower arc magnet pair 9 in the circumferential direction. The rotational speed control operation can be performed with almost no loss in size.

Alternatively, as shown in FIG. 6, the two arc-shaped magnet pairs are replaced with U-shaped magnets. Then, there is a rotor 3 between both magnetic poles of one U-shaped magnet 1, and a new U-shaped magnet 10 exists there. By rotating the new U-shaped magnet 10, the rotation speed control operation can be performed.

Rotational speed control can be easily performed by rotating a pair of arcuate field magnet pairs attached to the motor body, and even a part having no capacity can be easily accommodated including speed control. In addition, in a model motor having almost the same number of rotations, a combination of a plurality of motors having various rotational speeds can be applied to a model helicopter, for example. In the electric fan, since the speed control can be attached to the motor main body, it is not necessary to have a speed control device extending downward as in the conventional case, and it can be used even in a narrow space. In a large-scale motor, the arc magnet pair can be used by replacing it with a U-shaped magnet group.

  It is explanatory drawing which showed the implementation system by an asymmetrical magnetic field structure. Example 1   It is explanatory drawing which showed the implementation method which has arrange | positioned the bar magnet circularly. (Example 5)   It is explanatory drawing which showed the implementation method which has arrange | positioned the U-shaped magnet circularly. (Example 6)   It is explanatory drawing which showed the implementation method which has arrange | positioned the large and small U-shaped magnet up and down. (Example 8)   It is explanatory drawing which showed the implementation method of two sets of arc-shaped magnet pairs. Example 9   It is explanatory drawing which showed the implementation method by two U-shaped magnets. (Example 10)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 U type magnet 2 Soft iron yoke 3 Rotor 4 Bar magnet 5 Plastic material 6 Outer periphery soft iron yoke 7 U type small magnet group (control magnet)
8 Arc-shaped magnet pair (power magnet)
9 Arc-shaped magnet pair (control magnet)
10 U-shaped large magnet (control magnet)

Claims (4)

In a small DC motor, a speed control device that is made possible by rotating a field magnet group as two arc magnet pairs and one set as a control magnet pair. The field magnet is a plurality of U-shaped magnets arranged in a circle. Arranged so that all the magnetic flux of the inner magnetic pole is in the center direction of the rotor. Further, all the inner magnetic poles of the magnet group on one semicircular side are different from the inner magnetic poles of the magnet group on the other semicircular side. A speed control device that is made possible by increasing or decreasing the number of field magnets, or arranging another circular magnet group having the same arrangement in the lower part and rotating the lower magnet group in the circumferential direction. One U-shaped magnet is used as a field magnet for a DC motor, and a rotor is placed between both magnetic poles. A speed control device made possible by stacking other U-shaped magnets and manually rotating the stacked ones. A yoke is extended from both magnetic poles of one U-shaped magnet, and a rotor is placed between them. A speed control device that is made possible by bringing only one pole of a U-shaped magnet closer to the rotor, or bringing the magnetic pole of another U-shaped magnet closer thereto.

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