JP2002134315A - Anisotropic cylindrical magnet and its molding die magnetic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic segmental magnet which is capable of alleviating cogging phenomenon, without reducing motor torque. SOLUTION: A bipolar cylindrical magnet is provided with the inner surface of its cylinder serving as a working surface and the outer surface and two edge faces of the cylinder serving as non-acting surfaces. The axis of easy magnetization of magnetic powder on the cross section of the magnet in the direction vertical to its length direction increases gradually in the opposite pole directional component, while decreasing in the radial component as they approach a middle point between two poles from the center of reference magnetic pole in the circumferential direction, conforms to the circumferential direction in the middle point between the poles, then gradually increases again in the opposite pole directional component beyond the middle point between the two poles, and re-conforms to the radial direction at the center of the opposite pole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic cylindrical magnet and a magnetic circuit device for molding the same, and more particularly, to a cogging phenomenon of a motor used for a magnet stator and an outer rotor of a motor. The present invention relates to an anisotropic cylindrical magnet capable of preventing the resulting vibration, noise, and rotation unevenness, and improving a motor torque, and a molding die magnetic circuit device for manufacturing the magnet.

[0002]

2. Description of the Related Art Conventionally, as this kind of magnet, an isotropic cylindrical magnet, an axially oriented cylindrical magnet as shown in FIG. 8, and a radially oriented cylindrical magnet as shown in FIG. In order to further improve the motor torque, Japanese Unexamined Patent Publication No. 5-144632 discloses that the axis of easy magnetization of magnetic powder particles is symmetrically focused and oriented in the central region of the working surface as shown in FIG. Anisotropic cylindrical magnets have been proposed.

[0003]

However, the axially-oriented cylindrical magnet is good in terms of cogging, but has a problem in that the torque is small. The radially-oriented cylindrical magnet has a good torque, but the rotational direction of the rotor is small. In this case, the rate of change in the gap magnetic flux density is too large, and the cogging is poor. Further, there is a problem that neither the axially oriented type nor the radially oriented type cylindrical magnet is effectively used at both ends which are not opposed to the rotor. On the other hand, although the problem of cogging is improved in the above-mentioned symmetrically focused orientated cylindrical magnet, the improvement is slight, and there is a problem that noise and vibration are caused at a higher rotation speed. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides an anisotropic cylindrical magnet capable of improving both cogging or motor torque and cogging, and a molding die magnetic circuit device for manufacturing the same.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and have found that the easy axis of magnetization of magnetic powder in a section perpendicular to the longitudinal direction of the magnet is oriented in a specific direction. In this way, the rate of change of the gap magnetic flux density in the direction of rotor rotation in the vicinity of switching to the opposite pole can be reduced, cogging can be improved, and the longitudinal magnetic section is focused and arranged, so that the gap magnetic field between the rotor and the magnet stator can be improved. Was found to be able to be increased and the torque of the motor could be improved at the same time, leading to the present invention.

That is, a first aspect of the present invention is a two-pole cylindrical magnet having an inner peripheral surface of a cylinder as an active surface and an outer peripheral surface and both end surfaces as non-active surfaces, the magnet being perpendicular to the longitudinal direction of the magnet. As the direction of the axis of easy magnetization of the magnetic powder in the cross section of the direction approaches the distance between the two poles in the circumferential direction from the center of the reference magnetic pole, the component of the opposite pole direction gradually increases from the radial direction component, and becomes the circumferential direction between the poles. The anisotropic cylindrical magnet is characterized in that the component in the opposite pole direction increases again after the gap between the poles, and returns to the radial component at the center of the opposite pole.

In a preferred embodiment, the direction of the axis of easy magnetization of the magnetic powder in the longitudinal section is converged toward the central region of the working surface while being convexly curved from the non-working surface of the cross section. An anisotropic cylindrical magnet according to claim 1.

According to a third aspect of the present invention, there is provided the anisotropic cylindrical magnet according to the first or second aspect, comprising magnetic powder and a synthetic resin as main components.

A fourth aspect of the present invention is a molding die magnetic circuit device for manufacturing the anisotropic cylindrical magnet, wherein a two-pole having an inner peripheral surface of the cylinder as an active surface and an outer peripheral surface and both end surfaces as non-active surfaces. A magnetic circuit device for a molding die for a cylindrical magnet, wherein a permanent magnet is disposed inside a cylindrical cavity, and a magnetic circuit device for a molding die for an anisotropic cylindrical magnet is described.

In a preferred embodiment, the permanent magnet is disposed inside the cylindrical cavity, and the ferromagnetic portions are disposed on both sides of the cavity. This is a magnetic circuit device for molding dies.

In a preferred embodiment, a permanent magnet is provided inside the cylindrical cavity, and ferromagnetic portions are provided on both sides and outside the cavity.
It is a shaping | molding metal mold magnetic circuit apparatus of the described anisotropic cylindrical magnet.

According to a preferred embodiment, the permanent magnet disposed inside the cylindrical cavity has (BH) _max
The molding die magnetic circuit device for an anisotropic cylindrical magnet according to any one of claims 4 to 6, wherein the magnetic circuit device has a pressure of 26 MGOe or more and an iHc of 15000 Oe or more.

In a preferred embodiment, an electromagnet is used instead of a permanent magnet.
It is a molding die magnetic circuit device for an anisotropic cylindrical magnet described in the paragraph.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1A to 3A, an anisotropic cylindrical magnet according to the present invention has an inner peripheral surface as a working surface 1 and an outer peripheral surface and both end surfaces. Inactive surface 2 2
A pole-cylindrical magnet, wherein the direction of the axis of easy magnetization of the magnetic powder in a cross section perpendicular to the longitudinal direction of the magnet is the distance between the S and N2 poles in the circumferential direction from the center of the reference magnetic pole (eg, N pole). , The opposite pole direction component is gradually increased from the radial direction component, becomes a circulating direction at the gap M, and after passing the gap M, the opposite pole direction component is increased again to the opposite pole (for example, S
(Pole) An anisotropic cylindrical magnet characterized by returning to a radial component at the center.

The direction of the axis of easy magnetization of the magnetic powder in the longitudinal section of the cylindrical magnet may be a radial direction as shown in FIG. 1 (B).
From the viewpoint of effectively utilizing the surface magnetic field in the regions at both ends of the magnet, as shown in FIGS. 2 (B) and 3 (B), the working surface 1 is curved from the non-working surface 2 of the cross section in a convex shape. Are preferably converged toward the central region.

The anisotropic cylindrical magnet of the present invention may be either a synthetic resin magnet or a sintered magnet, but the synthetic resin magnet is free from cracks, chips and warpage during sintering, and is dimensionally stable. It is preferable in that it has excellent properties. As the magnetic powder in the synthetic resin magnet and the sintered magnet, rare earths such as ferrite magnetic powder, alnico magnetic powder and samarium-cobalt magnetic powder, neodymium-iron-boron magnetic powder, and samarium-iron-nitrogen magnetic powder Conventionally known anisotropic magnetic powders such as a system magnetic powder can be used.

As for the synthetic resin as the binder,
Any conventionally known one can be used. Typical examples are polyamide 6, polyamide 12, and polyamide 66.
Polyamide-based synthetic resin such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, polyethylene and polypropylene; homo- or copolymerized vinyl-based resin; polyurethane, silicone, polycarbonate, PBT, PET Polyester, polyetheretherketone, PP
Synthetic resins such as S, chlorinated polyethylene, chlorosulfonated polyethylene (trade name “Hypalon” of DuPont); isoprene, neoprene, styrene-butadiene,
Rubbers such as butadiene and acrylonitrile / butadiene; epoxy resins, phenolic synthetic resins and the like can be used. These may be used alone or as a mixture of two or more if necessary.

The mixing ratio of the magnetic powder to the synthetic resin as the binder is 40 to 70 vol% for the magnetic powder and 60 for the synthetic resin.
A range of -30 vol% is preferred. If the magnetic powder is less than 40 vol%, the magnetic properties are insufficient, while if it exceeds 70 vol%, the moldability tends to be poor. In addition, it goes without saying that a plasticizer, an antioxidant, a surface treatment agent, and the like conventionally used conventionally can be used according to the purpose.

An anisotropic cylindrical magnet according to the present invention is a magnetic circuit device for a two-pole cylindrical magnet, wherein the inner peripheral surface of the cylinder is an active surface and the outer peripheral surface and both end surfaces are non-active surfaces. It can be easily manufactured by a magnetic circuit device for forming a mold for an anisotropic cylindrical magnet, wherein a permanent magnet is provided inside the cavity.

An embodiment of the magnetic circuit device of the present invention will be described below by taking injection molding as an example. In the magnetic circuit device of FIG. 4, a permanent magnet 4 larger than the length of the cylindrical cavity 3 is disposed inside the cylindrical cavity 3. With such a configuration, a cylindrical magnet in which the direction of the axis of easy magnetization of the magnetic powder in the longitudinal section is uniformly oriented can be obtained (see FIGS. 1A and 1B). Such a magnet is effective when the magnet width and the rotor width are substantially equal.

In the magnetic circuit device shown in FIG. 5, a permanent magnet 4 shorter than the length of the cavity 3 is disposed inside the cylindrical cavity 3 and a ferromagnetic material is provided on both sides of the cavity 3 in the longitudinal direction. A part 8 is provided. With such a configuration, the cylindrical magnet that is focused and oriented toward the central region of the working surface while the direction of the axis of easy magnetization of the magnetic powder in the longitudinal cross section curves convexly from the non-working surface of the cross section. (See FIGS. 2A and 2B).

Further, in the magnetic circuit device of FIG. 6, the ferromagnetic portions 8 are provided not only on both sides in the longitudinal direction of the cavity 3 but also on the outside.
Compared with the magnetic circuit device of the above, the direction of the axis of easy magnetization of the magnetic powder in the cross section perpendicular to the longitudinal direction is slightly closer to the radial direction (see FIG. 3A), and the convex shape in the longitudinal cross section. Thus, a cylindrical magnet having a small degree of curvature and a focused orientation can be obtained (see FIG. 3B).

The magnets shown in FIGS. 2 and 3 are effective when the rotor width is narrower than the magnet width, and are appropriately designed according to the ratio of the rotor width / magnet width. The relationship between the length of the cavity 3 and the length of the permanent magnet 4 is appropriately determined by the rotor width / magnet width ratio, the angle of focusing orientation, and the like.

In the figure, reference numeral 8 denotes a ferromagnetic portion, 5 denotes a sprue, 6
Is a runner, and 7 is a projecting pin. The hatched portion is a ferromagnetic portion, and the stippled portion is a non-magnetic portion. As the ferromagnetic material, carbon steel such as S55C, S50C, S45C, and S40C, die steel such as SKD11 and SKD61, permendur, pure iron, and the like are used. On the other hand, as the nonmagnetic material, stainless steel, Copper beryllium alloy, high manganese steel Y
HD50, bronze, brass, non-magnetic super steel N-7 and the like are used.

As the permanent magnet, neodymium-iron-
A high energy product magnet such as a known rare earth sintered magnet such as a boron sintered magnet or a samarium-cobalt sintered magnet is suitable. Permanent magnet is 26 MGOe at (BH) _max
Those having the above and iHc of 15000 Oe or more are preferable.

Further, an electromagnet may be used instead of the permanent magnet, and a conventionally known electromagnet using a soft magnetic member and a coil can be used. The soft magnetic member has a saturation magnetic flux density of 1500
Those having 0 gauss or more are preferable, and those having 20,000 gauss or more are more preferable.

In the case of a synthetic resin magnet, in addition to the above-described injection molding, known methods such as compression molding can be used. In the case of a sintered magnet, well-known wet molding and dry molding are used to form a green. Can be used as a method.

In order to manufacture the anisotropic cylindrical magnet of the present invention using a mold in which the above-described magnetic circuit for injection molding is set, a sprue 5 and a runner 5 are made of a resin magnet composition containing magnetic powder and synthetic resin as main components. 4, the magnetic powder particles are filled in the cylindrical cavity 3 along the lines of magnetic force, and in the case of FIG.
An anisotropic cylindrical magnet as shown in FIGS. 1A and 1B is obtained. On the other hand, in the cases of FIGS. 5 and 6, as shown by arrows, the easy axis of magnetization of the magnetic powder particles is oriented so as to diverge from the working surface to the non-working surface on the N pole side, and to the non-working surface on the S pole side. FIG. 2 is oriented to focus on the central region of the working surface from FIG.
An anisotropic cylindrical magnet as shown in FIGS. 3A and 3B or FIGS. 3A and 3B is obtained. In addition, sprue 5, runner 6
Can be heated by disposing a heater or the like in the vicinity thereof. In addition, well-known compression molding machines and extrusion molding machines can be used, and a magnetic circuit similar to that of the injection molding mold may be assembled.

In the anisotropic cylindrical magnet according to the present invention, the direction of the axis of easy magnetization of the magnetic powder in the cross section perpendicular to the longitudinal direction of the magnet approaches between the two poles in the circumferential direction from the center of the reference magnetic pole. Is gradually oriented from the radial direction component to the opposite pole direction component, becomes a circulating direction between the poles, and after passing the gap, increases the opposite pole direction component again, and is oriented to return to the radial direction component at the center of the opposite pole. Therefore, the rate of change of the gap magnetic flux density in the rotor rotation direction is reduced, and cogging is greatly improved.

Further, in the longitudinal section, when the direction of the axis of easy magnetization of the magnetic powder is focused and oriented at a large angle while being convexly curved from the non-working surface, both ends can be effectively used, That is, when the focusing orientation of the longitudinal section is applied according to the ratio between the rotor width and the magnet stator width, the gap magnetic field between the rotor and the magnet stator can be increased, and the torque of the motor is improved. be able to. Thus, the cylindrical magnet of the present invention is useful as a magnet stator or outer rotor for a motor.

FIG. 7 is a schematic diagram showing a motor using the anisotropic cylindrical magnet of the present invention (the magnet of FIG. 2 is shown in the figure) as a stator. In the figure, the ferromagnetic case 9,
It comprises a magnet stator 10 and a soft magnetic rotor 12 via a shaft 11, and the anisotropic cylindrical magnet 13 obtained by the present invention is used as the magnet stator 10. 7, 14 is a rotor excitation coil, 15 is a brush, 16 is a washer, 17 is a bearing, and 18 is a lead wire.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but these do not limit the present invention at all.

Examples 1 to 3 and Comparative Examples 1 and 2 FIGS. 1 to 3 (Examples 1 to 3) or FIGS. 9 and 9 were used, respectively, by using an injection mold in which the magnetic circuits shown in Table 1 were set. An anisotropic cylindrical magnet as shown in No. 10 (Comparative Examples 1 and 2) was manufactured under the following manufacturing conditions. As a mold material for forming the cavity, S45C was used as a ferromagnetic material, and high manganese steel YHD50 (manufactured by Hitachi Metals, Ltd.) was used as a nonmagnetic material.

Next, motors as shown in FIG. 7 were assembled using the anisotropic cylindrical magnet as a stator. The motors incorporating the anisotropic cylindrical magnets of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for motor torque and cogging. Table 1 shows the evaluation results. still,
The evaluation of the motor torque was shown by a relative comparison with the case of Comparative Example 1 being 100. In addition, the cogging was evaluated in three steps based on the following criterion based on the sense of resistance in the rotating direction when the shaft was slowly turned by hand in a state in which no current was supplied with an anisotropic cylindrical magnet incorporated in the motor. A: Almost no resistance. ：: There is some resistance. Δ: There is considerable resistance. X: There is considerable resistance.

(Blending) Magnetic powder: Ferrite magnetic powder (magnet plumbite-type strontium ferrite having an average particle diameter of 1.5 μm) 68 vol% Synthetic fat: Polyamide 12 36 vol% Plasticizer: TTS (isopropyl triisostearoyl titanate) 1 vol %

(Molding conditions) Injection molding conditions (Nippon Steel Works: J-50M magnetic orientation injection molding machine used) Injection cylinder temperature: 280 ° C Mold temperature: 100 ° C Injection pressure: 1500 kg / cm ² Cooling time: 25 seconds Injection cycle: 40 seconds

[0036]

[Table 1]

As is clear from Table 1, the anisotropic cylindrical magnet of the present invention can improve not only cogging but also motor torque.

[0038]

As described above, in the anisotropic cylindrical magnet of the present invention, the direction of the axis of easy magnetization of the magnetic powder in the cross section perpendicular to the longitudinal direction has two poles in the circumferential direction from the center of the reference magnetic pole. As the distance between the poles increases, the opposite pole direction component gradually increases from the radial direction component, gradually becomes the circulating direction between the poles, and after passing the gap, the opposite pole direction component increases again and returns to the radial direction component at the center of the opposite pole. Because it is oriented, when the rotor rotates and crosses the magnetic field formed by the stator, the rate of change of the gap magnetic flux density in that magnetic field decreases,
For example, when mounted on a motor, cogging can be more effectively improved. Further, since the gap magnetic field between the rotor and the magnet stator can be increased by setting the longitudinal section to the convergent orientation, the motor torque can be simultaneously improved.

Further, the anisotropic cylindrical magnet of the present invention is easily manufactured by the inner magnetic circuit device and does not generate a current magnetic field as in the case of the outer magnetic circuit device. It becomes a magnet that is focused while convexly curved,
It is possible to exhibit the above-described effects.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the anisotropic cylindrical magnet of the present invention, wherein (A) shows a focused orientation state of an easy axis of magnetization of magnetic powder in a direction perpendicular to a longitudinal direction, and (B) 3 shows a focused orientation state of an axis of easy magnetization of a magnetic powder in a longitudinal direction.

FIG. 2 is a schematic cross-sectional view showing another example of the anisotropic cylindrical magnet of the present invention, in which (A) shows a focused orientation state of an axis of easy magnetization of magnetic powder in a direction perpendicular to a longitudinal direction, and (B). () Shows the focused orientation state of the easy axis of the magnetic powder in the longitudinal direction.

FIG. 3 is a schematic cross-sectional view showing still another example of the anisotropic cylindrical magnet of the present invention, wherein (A) shows a focused orientation state of an easy axis of magnetization of a magnetic powder in a direction perpendicular to a longitudinal direction, B) shows the focused orientation state of the easy axis of the magnetic powder in the longitudinal direction.

FIG. 4 is a schematic sectional view showing an example of a molding die magnetic circuit device for producing the anisotropic cylindrical magnet of the present invention.

FIG. 5 is a schematic cross-sectional view showing another example of a molding magnetic circuit device for producing the anisotropic cylindrical magnet of the present invention.

FIG. 6 is a schematic sectional view showing still another example of a molding die magnetic circuit device for producing the anisotropic cylindrical magnet of the present invention.

FIG. 7 is a schematic sectional view showing a motor incorporating the anisotropic cylindrical magnet of the present invention.

FIG. 8 is a schematic sectional view showing a conventional anisotropic cylindrical magnet (axial orientation).

FIG. 9 is a schematic sectional view showing a conventional anisotropic cylindrical magnet (radial orientation).

FIG. 10 is a schematic sectional view showing a conventional anisotropic cylindrical magnet (symmetric focusing orientation).

FIG. 11 is a schematic sectional view showing a molding die magnetic circuit device for producing a conventional anisotropic cylindrical magnet (radial orientation).

FIG. 12 is a schematic sectional view showing a molding die magnetic circuit device for producing a conventional anisotropic cylindrical magnet (symmetric focusing orientation).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Working surface 2 Non-working surface 3 Cylindrical cavity 4 Permanent magnet 5 Sprue 6 Runner 7 Protruding pin 8 Ferromagnetic part 9 Ferromagnetic case 10 Magnet stator 11 Shaft 12 Soft magnetic rotor 13 Anisotropic cylindrical magnet 14 Rotor excitation Coil 15 Brush 16 Washer 17 Bearing 18 Lead wire

Claims (8)

[Claims] 1. A two-pole cylindrical magnet having an inner peripheral surface as a working surface and an outer peripheral surface and both end surfaces as non-working surfaces, the magnetization of a magnetic powder in a cross section perpendicular to the longitudinal direction of the magnet. As the direction of the easy axis approaches the distance between the two poles in the circumferential direction from the center of the reference magnetic pole, the opposite pole direction component gradually increases from the radial direction component, becomes the circumferential direction between the poles, and reverses again after crossing the poles. An anisotropic cylindrical magnet characterized by increasing the polar component and returning to the radial component at the center of the opposite pole. 2. The method according to claim 1, wherein the direction of the axis of easy magnetization of the magnetic powder in the longitudinal section is focused toward the central region of the working surface while being convexly curved from the non-working surface of the cross section. Isotropic cylindrical magnet. 3. The anisotropic cylindrical magnet according to claim 1, which comprises magnetic powder and a synthetic resin as main components. 4. A permanent magnet is disposed inside a cylindrical cavity in a two-pole cylindrical magnet forming mold magnetic circuit device having a cylindrical inner peripheral surface as an active surface and an outer peripheral surface and both end surfaces as non-active surfaces. A molding die magnetic circuit device for an anisotropic cylindrical magnet, characterized in that: 5. The molding die magnetic circuit device for an anisotropic cylindrical magnet according to claim 4, wherein a permanent magnet is disposed inside the cylindrical cavity, and ferromagnetic portions are disposed on both sides of the cavity. . 6. The molding die magnet for an anisotropic cylindrical magnet according to claim 4, wherein a permanent magnet is disposed inside the cylindrical cavity, and ferromagnetic portions are disposed on both sides and outside of the cavity. Circuit device. 7. A permanent magnet disposed inside the cylindrical cavity, (BH) different according to any one of claims 4-6 in _{ma x} at 26 MGOe or more and and iHc at 15000 Oe or more Magnetic circuit device for forming mold for isotropic cylindrical magnet. 8. The molding die magnetic circuit device for an anisotropic cylindrical magnet according to claim 4, wherein an electromagnet is used instead of the permanent magnet.