JPS637159A - Micromotor - Google Patents

Abstract

PURPOSE:To reduce the variation in the rotating speed per torque of a micromotor by using a rubber magnet or a plastic magnet of a specific range of a ratio of thickness to outer diameter, as a field. CONSTITUTION:A cylindrical rubber magnet or a plastic material 1 for forming a field is secured to the inner surface of a cylindrical motor case 2. A shaft 4 is rotatably supported by a bearing provided in the case 2, and the rotor 3 is provided in the magnet 1. The outer diameter of the motor is set to 15mm or less, and the ratio of the thickness to the outer diameter of the magnet 1 to 0.085-0.125.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a micromotor using a rubber magnet or a plastic magnet, and in particular to a micromotor that uses a rubber magnet or a plastic magnet. The present invention relates to a micromotor using a rubber magnet or a plastic magnet, in which the magnetic field is set within a predetermined range.

(Prior Art) Generally, in micro motors with a motor outer diameter of 15 m or less, attempts have been made to use anisotropic sintered strontium ferrite magnets. Such rubber magnets are made by magnetizing strontium ferrite powder mixed with about 10% rubber, and are unbreakable and can be processed into any shape.

Figure 5 (A) shows a cylindrical magnet with an outer diameter D and a thickness t by winding such a rectangular sheet of rubber magnet into a cylindrical shape, and this is shown in Figure 5 (B). The magnetic field is arranged closely on the inner surface of the motor case 2, and the rotor 3 is arranged inside the magnetic field to form a micromotor. Note that 4 is a motor shaft, and a bearing (not shown) provided in the motor case 2 is rotatably supported by the part.

(Problems to be solved by the invention) By the way, such anisotropic sintered strontium ferrite magnets have to be polished many times and the yield is poor, resulting in extremely high costs. It has drawbacks, and therefore, motors using this type of rubber magnet have not been produced to date, and the reality is that, of course, no data regarding the optimal design has been obtained.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, uses low-cost rubber magnets or plastic magnets, and uses thin cylinders with a minimum dimensional ratio that changes the rotational speed relative to the load. Therefore, the micromotor of the present invention has a cylindrical motor case, a motor
A cylindrical rubber magnet or plastic magnet is fixed to the inner surface of the case and constitutes the field, and the bearing provided in the motor case has a shaft rotatably supported by the motor case, and the magnet is provided within the cylindrical magnet. In a micromotor with a circular rotor, the outer diameter of the motor is 1
5 cranes or less, and the thickness to outer diameter ratio of the magnet is 0.0.
85 to 0.125. below,
This will be explained with reference to the drawings.

(Example) Generally, one of the ways to express the performance of a motor is the number of revolutions per torque (rpm/gem). It is desirable to design the motor volume to be as small as possible.

Fig. 1 is a diagram showing the rotation speed to torque ratio with respect to the thickness to outer diameter ratio (1/D) of the low-cost rubber magnet used in the micromotor of the present invention, and Fig. 2 is the rubber magnet shown in Fig. 1. This is a diagram showing the change in magnetic flux with respect to t/D of
This is data obtained for a 5tm motor.

As can be seen from Figure 1, the rotation speed to torque ratio is t/D
is the smallest value around 0.10, and as shown by the dotted line in the figure, when t/D is in the range of about 0.085 to 0.125, the rotation speed to torque ratio can be satisfied as approximately 420 or less. can do.

On the other hand, as can be seen from Figure 2, when t/D is 0°09 or more, the magnetic flux increase rate slightly changes due to magnetic saturation.
The range up to about 0.125 is not a complete magnetic saturation region, but can be said to be a range that can be used without problems.

FIG. 3 is a diagram showing the change in winding resistance with respect to the core diameter, and shows the case where the outer diameter of the magnet is constant.

Since the outer diameter of the magnet is constant, the thinner the magnet, the larger the core diameter.With the same number of windings (fixed at 52 turns in this example), the larger the core diameter (the larger the vA diameter), the larger the core diameter. Since it can be made thicker, the winding resistance becomes smaller as shown in the figure.The above-mentioned t/D is 0.085.
In the range of ~0.125, the magnet thickness is relatively thin;
Therefore, the winding resistance can also be reduced.

FIG. 4 shows the change in rotational speed (N/T) with respect to load as seen from the motor characteristic table.

Although the case where a low-cost rubber magnet is used as a field magnet has been described above, the above description can be similarly applied to a low-cost plastic magnet.

(Effects of the Invention) As is clear from the above description, according to the present invention, a low-cost rubber magnet or plastic magnet is used in a cylindrical motor with a limited capacity and an outer diameter of 15 mm or less. and set the magnet thickness to outer diameter ratio to 0.
．． By selecting the range from 0.085 to 0.125, it is possible to minimize the change in rotational speed per torque.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the rotation speed to torque ratio with respect to the thickness to outer diameter ratio of the rubber magnet used in the micromotor of the present invention, Fig. 2 is a diagram showing the change in magnetic flux with respect to the thickness to outer diameter ratio of the rubber magnet, Figure 3 is a diagram showing the change in winding abrasive resistance with respect to the core diameter, Figure 4 is a diagram showing the change in rotation speed (N/T) with respect to load from the motor characteristics table, and Figure 5 (A) is a diagram showing the change in the winding resistance with respect to the core diameter. FIG. 5(B) shows a schematic diagram of a micromotor using a cylindrical rubber magnet. In the figure, ■ represents a rubber magnet, 2 represents a motor case, 3 represents a rotor, and 4 represents a shaft. Patent applicant Mabuna Motor Co., Ltd. Agent Patent attorney Mori 1) Hiroshi (2 others) First country
Ko 2 Eup (Al 烹 5 国, 8) April 23, 1985 Commissioner of the Patent Office Kuro 1) Akio Yu 1, Indication of the case 1986 Patent Application No. 150398 2, Title of invention Micromotor 3, Amendment Patent applicant address: 430 Matsuhidai, Matsudo City, Chiba Prefecture Name: Mapuchi Motor Co., Ltd. Representative: Takashi Umabuchi - 4, Agent address: Sawara Mansion 3FC, 4-17-1 Nishi-Nippori, Arakawa-ku, Tokyo Name (7484) Patent attorney Mori 1) Hiroshi (2 others) 5
, Number of inventions increased by amendment None 6. Subject of amendment
Specification “Detailed Description of the Invention Column” 7, Contents of the Amendment Contents of the Amendment as attached (1) Page 2, line 8 of the specification “This has been attempted.”
Correct it as follows. However, because the anisotropic sintered strontium ferrite magnet is expensive and difficult to process to make it suitable for field magnets in small motors, This was decided to be taken into consideration. (2) From page 2, line 13 to page 3, line 1 of the specification “5th
Figure (A) is supported. ” will be deleted. (3) In the third line of page 3 of the specification, replace the phrase “like this” with “
As mentioned above.'' (4) The phrase ``Therefore, it is one of this type---naturally the most'' in lines 6 to 8 of page 3 of the specification should be amended as follows. ``Construction with a rubber magnet has come to be considered, but of course it is the best for use in the motor world.'' (5) Page 4, line 10 of the specification ``--Generally.'' Correct as follows: [In Figure 5, 1 in Figure 1 represents the rubber magnet. 2 represents the motor case, 3 represents the rotor, and 4 represents the shaft. In addition, Figure 5 (A) is a rectangular sheet of such a rubber magnet wound into a cylindrical shape with an outer diameter of t to form a cylindrical magnet with a thickness of t.5 This is shown in Figure 5 (B).
The magnetic field is arranged closely on the inner surface of the motor case 2, and the rotor 3 is arranged inside the magnetic field to form a micromotor. in general,". that's all.

Claims (1)

[Claims] It has a cylindrical motor case, a cylindrical rubber magnet or plastic magnet fixed to the inner surface of the motor case and forming a field, and a shaft rotatably supported by a bearing provided in the motor case. , in a micromotor equipped with a rotor provided in a cylindrical magnet, the outer diameter of the motor is 15 mm or less, and the thickness to outer diameter ratio of the magnet is 0.085 to 0.125.
A micro motor characterized by the following.