JPH05122900A - Rotor for fan motor - Google Patents

Abstract

PURPOSE:To manufacture a thin and lightweight product with less rotational irregularities or vibrational noises at a low cost by integrating a fan section and an exciting magnet section formed of plastic magnet composition together with a shaft into one unit. CONSTITUTION:A disc-like exciting magnet section 2 and a fan section 1 on the peripheral surface thereof are formed of plastic magnet composition. A metal shaft 4, the magnet section 2 and the fan section 1 formed of the plastic magnet composition are integrated into one unit. A bearing 6 and an exciting coil 5 are provided in a circular recess section formed around the shaft 4, and the whole is stored into a case 7. According to the constitution, a thin and lightweight product excellent in high speed rotation and having less rotational irregularities or vibrational noises is manufactured at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan motor rotor suitable for use in, for example, a cooling fan in OA equipment, and particularly, to reduce its thickness and weight.

[0002]

2. Description of the Related Art Conventionally, as a rotor for a fan motor, a rotor having a structure as shown in FIGS. 3 (a) and 3 (b) has been typical, but such a rotor has the following drawbacks. It was 1) There are a total of five parts, including the fan 8, the magnet 9 for excitation, the ferromagnetic material 10 such as an iron plate as the back yoke, the shaft 11 and the bush 12, and the dimensions can be determined by a manufacturing process such as bonding or caulking. The rotation center of gravity often shifts when assembled as a motor, which not only causes uneven rotation, but also causes noise and vibration. 2) In order to adjust the above problems, it is often the case that a strobe meter is used and an adjustment sheet is affixed to the parts that make up the rotor fan, but such repair requires a great deal of workability. It was causing a decline. 3) The magnet adsorbed on the iron plate as the back yoke may come off after shipping or during use. 4) Since many parts are stacked and assembled, there is a limit to the thinness and weight reduction of the fan motor. That is, it was not possible to design thin or small and light ones.

In general, rare earth magnets are used when aiming to make them light, thin and short by using many parts. In fan motors, high-speed rotation is required because the purpose is to secure a larger air volume, but since the surface magnetic field is too strong when the magnet used is a rare earth magnet, counter electromotive force is generated,
On the contrary, high-speed rotation was hindered. That is, when using a magnet with a surface magnetic field that is too strong, such as a rare earth magnet,
Due to the characteristics of fan motors, it was impossible to make them thinner and smaller.

[0004]

SUMMARY OF THE INVENTION The present invention advantageously solves the above problems and provides a rotor for a fan motor which can be advantageously made thin and compact without impeding high-speed rotation. It is intended to be a suggestion.

That is, according to the present invention, at least the fan portion and the exciting magnet portion are made of a plastic magnet composition,
A rotor for a fan motor, which is formed by integrally molding such a plastic magnet composition member with a shaft.

In the present invention, when the magnet portion for excitation has a disk shape, it is preferable that the axis of easy magnetization of the magnetic powder particles of the magnet portion is in a polar anisotropic orientation with the inner plane as the acting surface.

Further, in the present invention, when the magnet part for excitation has a cylindrical shape, the easy axis of magnetization of the magnetic powder particles of the magnet part may be oriented in a polar anisotropic manner with the inner peripheral surface of the cylinder as the acting surface. preferable.

The rotor of the present invention will be described below in comparison with a conventional rotor. FIG. 1 (a) shows a rotor for a fan motor according to the present invention, in which the exciting magnet portion is disk-shaped, and FIG. 2 (a), a rotor for a fan motor according to the present invention, in which the exciting magnet portion is cylindrical. Are each shown in a vertical section. In the figure, reference numeral 1 is a fan portion, 2 is an exciting magnet portion, and 3 is a bush portion. In the present invention, at least the fan portion 1 and the exciting magnet portion 2, and when the bush portion 3 is provided as shown in FIG. 2A, the bush portion 3 is also included and is made of a plastic magnet composition. Further, the plastic magnet composition member is integrally molded with the shaft 11.

As described above, in the conventional rotor, as shown in FIG. 3, the fan body, the magnet for excitation and the ferromagnetic material, which are individually manufactured, and the bush, if necessary, are all provided in the present invention. The feature is that it is integrally formed of a plastic magnet composition. Regarding the orientation of the magnetic powder particles on the working surface of the exciting magnet portion,
Although not particularly limited, the disc-shaped magnet shown in FIG. 1A may have an inner plane polar anisotropic orientation, and the cylindrical magnet shown in FIG. 2A may have an inner circumferential surface polar anisotropic orientation. desirable. This is because the magnetic field that penetrates the non-working surface side is extremely small in the ultra-anisotropic orientation, so that dust of the ferromagnetic system and adhesion of fine powder can be effectively prevented.

[0010]

As described above, in the present invention, all rotor parts except shyato are made of the plastic mag composition, and the plastic mag composition member is formed integrally with the shaft.
As described above, according to the present invention, since the fan portion, the magnet portion for excitation, and the like are integrally formed of the pramag composition, the dimensions do not deviate during the manufacturing process. In addition, since the thickness can be made thinner than in the conventional case, FIG.
As shown in (b), when it is incorporated in an actual machine, its thinning and miniaturization are advantageously achieved. 1 (b) and 2 (b), 5 is an exciting coil, 6 is a bearing, and 7 is a case.

As the pragmag composition, any conventionally known one can be used, but a ferrite system is particularly preferable when high speed rotation is expected. When using rare earth-based magnetic powder, it is important to adjust the content in Plamag to an appropriate amount.

Here, as the magnetic particles, known ones such as ferrite type, samarium-cobalt type, neodymium-iron-boron type and alnico type can be used, but as mentioned above, the ferrite type is most preferable. Regarding the synthetic resin which is the binder, any of the already known thermoplastic resin and thermosetting resin can be used, but in the present invention, since the fan portion is also formed by such synthetic resin, the flexibility is too good. Rubber-based and elastomer-based materials that cannot maintain their shape after molding are excluded. Regarding the amount of magnetic powder, if the magnetic powder is ferrite type,
About 30 to 60 vol% is preferable, and about 10 to 30 vol% is preferable for rare earth type.

Regarding the shaft, the conventionally known SUS
Metals, including stainless steel such as 420 J2 and SUS 304, BN, alumina, zirconia and other ceramics, and synthetic resins with a softening temperature of 300 ° C or higher are advantageously suitable.

Regarding the orientation direction of the magnetic powder particles in the exciting magnet portion, any of the already known orientation directions, that is, isotropic, thickness direction orientation and polar anisotropic orientation are suitable, but the magnetic field from the non-acting surface is also applicable. To prevent this, see FIGS. 4 (a) and 4 (b).
As described above, it is desirable to have the extremely anisotropic orientation as shown in FIG. Therefore, in order to concentrate the magnetic field on the working surface and to secure the mechanical strength, the content of magnetic powder should be appropriately reduced, and all parts other than the shaft should be made of plastic magnet composition. It is most desirable to have a radial focusing orientation.

[0015]

EXAMPLES Example 1 A fan motor rotor shown in FIGS. 1A and 3A was produced under the following conditions.

Raw material magnetic powder A: Ferrite magnetic powder (magnetoplumbite strontium ferrite having an average particle size of 1.5 μm) Magnetic powder B: samarium-cobalt magnetic powder (2-17 system; average particle size 10 μm)

Compounding composition A (ferrite compounding) Magnetic powder: 40 vol% Polyamide 12: 60 vol% Compounding B (samarium-cobalt compounding) Magnetic powder: 16 vol% Polyamide 12: 84 vol% Compounding C (samarium-cobalt compounding) ) Magnetic powder: 40 vol% Polyamide 12: 60 vol%

-Molding method: Plamag injection molding conditions Pellet mix used: Mixture A Molding machine: Coil built-in magnetic field orientation injection molding machine Injection cylinder temperature: 260 ℃ Magnetic circuit of mold: Inner surface anisotropic mold temperature: 80 ℃ Injection pressure: 1200kg / cm ² Excitation time: 15 seconds Cooling time: 30 seconds Injection cycle: 50 seconds

-Dimensions of the magnet part for excitation Plamag: Outer diameter: 34 mm, Inner diameter (shaft diameter): 4 mm, Thickness: 4 mm Sintering: Outer diameter: 32 mm, Inner diameter (shaft diameter): 6 mm, Thickness: 4 mm

Table 1 shows the results obtained by examining various characteristics of the fan motor in which the rotor thus obtained is incorporated in an actual machine.
Shown in.

[0021]

[Table 1]

According to the present invention, when the rotor member excluding the shaft is integrally formed of the ferrite type plastic mag composition, compared with the conventional rotor, high speed rotation, uneven rotation, mechanical strength, material cost and assembly cost are all good. there were.

Example 2 Under the same conditions as in Example 1, a fan motor rotor shown in FIGS. 2 (a) and 3 (b) was produced. Table 2 shows the results of an examination of various characteristics of the fan motor in which the rotor thus obtained is incorporated in an actual machine.

[0024]

[Table 2]

Even when the exciting magnet portion is cylindrical, all of the high speed rotation, uneven rotation, mechanical strength, material cost and assembly cost are better than those of the conventional rotor, as in the first embodiment.

[0026]

As described above, according to the present invention, particularly, the high-speed rotatability is excellent, there is no rotation unevenness, that is, the vibration noise is extremely small, the magnet does not fall off by the bonding method, and the assembly cost can be greatly reduced. A rotor for a fan motor can be obtained, which is extremely useful in reducing the thickness and weight of the rotor.

[Brief description of drawings]

FIG. 1 (a) is a vertical cross-sectional view of a rotor for a fan motor according to the present invention in which a magnet portion for excitation is disk-shaped.
(B) is a longitudinal sectional view of a fan motor in which the rotor is incorporated in an actual machine.

FIG. 2 (a) is a vertical cross-sectional view of a rotor for a fan motor according to the present invention, in which a magnet portion for excitation is disk-shaped.
(B) is a longitudinal sectional view of a fan motor in which the rotor is incorporated in an actual machine.

FIG. 3A is a vertical cross-sectional view of a conventional fan motor rotor in which an exciting magnet portion has a disk shape. (B)
FIG. 8 is a vertical cross-sectional view of a conventional fan motor rotor in which a magnet portion for excitation has a cylindrical shape.

FIG. 4A is a schematic view of a disk-shaped magnet having a polar anisotropic orientation. (B) is a schematic view of a cylindrical magnet having a polar anisotropic orientation.

[Explanation of symbols]

 1 Fan Part 2 Excitation Magnet Part 3 Bushing Part 5 Excitation Coil 6 Bearing 7 Case 8 Fan 9 Excitation Magnet 10 Ferromagnetic Plate 11 Shaft 12 Bush

Claims (3)

[Claims] 1. A rotor for a fan motor, wherein at least a fan part and an exciting magnet part are made of a plastic magnet composition, and the plastic magnet composition member is integrally molded with a shaft. 2. The excitation magnet portion according to claim 1, wherein the magnet portion for excitation has a disk shape, and the easy axis of magnetization of the magnet portion magnetic powder particles is
A rotor for a fan motor that has a plane inside the disk as the working surface and is in a very anisotropic orientation. 3. The exciting magnet portion according to claim 1, wherein the magnet portion for excitation has a cylindrical shape, and the axis of easy magnetization of the magnetic powder particles of the magnet portion is
A rotor for a fan motor that has an extremely anisotropic orientation with the inner surface of the cylinder as the working surface.