JP3049134B2 - 2-pole cylindrical magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-pole cylindrical magnet suitable for use as a permanent magnet type stator for a long-axis motor, an outer rotor and the like. It is intended to effectively prevent the resulting vibration and noise, and furthermore, the occurrence of uneven rotation.

[0002]

2. Description of the Related Art Conventionally, as a two-pole cylindrical magnet used for a long-axis motor, the orientation direction of the axis of easy magnetization of the magnetic powder particles of the magnet has a cross section shown in FIG. 1 (a) or (b). In the cross section in the longitudinal direction, the orientation shown in FIG.
The following orientations have been used. In the figure, the thin line indicates the orientation direction of the axis of easy magnetization of the magnetic powder particles. Usually, FIG. 1A is called the axial type orientation, and FIG. 1B is called the radial type orientation.

When a two-pole cylindrical magnet having such an orientation is used as a stator, the gap magnetic flux density at the boundary greatly changes when the rotor rotates and crosses the magnetic field formed by the stator.
An adverse effect called cogging has occurred. Such cogging is not preferable because it causes delicate vibrations, noise and uneven rotation.

As a solution to this problem, FIG.
As shown in (1), a divergent magnet has been proposed in which the orientation direction of the axis of easy magnetization of the magnetic powder particles in the cross section is diverged toward the working surface, and the change in the gap magnetic flux density at the boundary of the stator magnetic field is reduced. However, in the case of such magnetic powder orientation, although the change amount of the gap magnetic flux density in the rotational direction is small, the absolute value of the surface magnetic field on the working surface is small, so that the torque is reduced.

The substantial working width in the longitudinal direction of the conventional motor stator is as shown by the symbol a in FIG. 2, and the rotor 9, because of the bearing 9, the washer 10, the leaf spring 11, the brush 12, etc. Was as narrow as the magnetic pole width. As described above, since the width of the stator was not sufficiently utilized, the obtained torque could not be said to be an effective utilization of the width of the magnet. In the figure, reference numeral 13 is a cylindrical magnet, 14 is a rotor magnetic pole, 15 is a rotor excitation coil, 16 is a shaft, and 17 is a ferromagnetic case.

[0006]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and effectively alleviates the change in the gap magnetic flux density, and at the same time, cylindrical magnets which have not been effectively used conventionally. An object of the present invention is to propose a two-pole cylindrical magnet capable of effectively suppressing the occurrence of cogging without effectively lowering the torque by effectively utilizing both ends in the longitudinal direction.

[0007]

According to the present invention, the axes of easy magnetization of the magnetic powder particles in two opposing regions of the inner peripheral surface of the cylindrical magnet are set at least near both ends of the active surface region in the O-shaped cross section. Is focused on the non-working surface side, in other words, by making the orientation diverge toward the working surface side, thereby preventing the occurrence of cogging, while, in the longitudinal section, the central region corresponding to the rotation region of the rotor pole, that is, the working surface The above-mentioned object is achieved by improving the surface magnetic field on the effective working surface by performing the focusing orientation, thereby improving the torque without lowering the torque.

[0008] That is, the present invention is a cylindrical magnet having two opposing regions of an inner peripheral surface of a cylinder having an O-shaped cross section as an active surface, and the orientation of the axis of easy magnetization of magnetic powder particles of the magnet. The direction is such that at least the vicinity of both ends in the working surface region of the cross section of the magnet converges to the non-working surface side of the magnet, and the central region of the inner working surface in the longitudinal section including the working surface and the axis of the magnet. Is a two-pole cylindrical magnet.

[0009]

According to the present invention, the surface magnetic field on the substantially working surface of the cylindrical magnet is improved by controlling the orientation of the magnetic powder particles in the magnet material by devising the magnetic circuit of the molding die. , To suppress the occurrence of cogging. More specifically, the width of the magnetic pole in the cross section of the cylindrical cavity is set such that the main pole and the counter electrode disposed on the outer periphery of the working surface area are narrower than the magnetic pole width of the intermediate magnetic pole disposed inside the cylinder, and the longitudinal direction. Regarding the magnetic pole width in the cross section, by narrowing the width of the intermediate magnetic pole than the main pole or counter electrode, the magnetic force lines in the molding die cavity are focused on the non-working surface side at least in the vicinity of both ends in the cross section, and In the longitudinal section, it is focused on the central area of the inner working surface.

With respect to the magnet material charged in the cavity, the orientation direction of the magnetic powder particles is aligned with the direction of the line of magnetic force, that is, at least in the cross section, at least the vicinity of both ends is diverged to the working surface side, and in the longitudinal cross section, Can be focused on a substantially active surface inside the magnet,
As a result, it is possible to effectively prevent the occurrence of cogging without lowering the surface magnetic field on the substantial working surface of the magnet.

FIGS. 1 (c) and 1 (d) and (b) and (c) show a typical cross section and a longitudinal section of a cylindrical magnet in which magnetic powder particles are oriented according to the present invention. FIG. 3C shows a case where all the magnetic powder particles in the working surface region are focused on one point on the non-working surface side in the cross section, and FIG. (B) is a case where the light is focused linearly from the outer peripheral surface to the central region in the longitudinal section (simple focusing orientation), and FIG. This is a case where focusing is performed from the center of the side surface and both end surfaces to the center portion of the action surface region (side end surface side focusing orientation). As described above, in the cylindrical magnet according to the present invention, since the magnetic powder particles at least at both ends of the working surface region in the cross section converge on the non-working surface side, in other words, diverge on the working surface side, the rotor generates the stator magnetic field. The amount of change in the direction of rotation of the gap magnetic flux density when crossing the boundary can be reduced, so that the occurrence of cogging can be effectively prevented.

By the way, when the orientation direction of the magnetic powder particles in the cross section of the stator is the divergent orientation as described above, as described above, the absolute value of the surface magnetic field on the working surface is reduced, and the torque is reduced. As a result, this point can be solved by setting the orientation direction of the magnetic powder particles in the longitudinal section to the simple focusing orientation as described above or to the side edge focusing orientation at both ends. 3 and 4
FIG. 1 shows a state in which the cylindrical magnet according to the present invention is incorporated as a stator of a DC motor. As is apparent from a comparison between FIGS. 3 and 4 and the above-described FIG. 2 in which the conventional motor is incorporated, useless magnetic flux exists in the conventional magnet as shown in FIG. In contrast, FIG.
In the inventive magnets shown in (b) and (c), all magnetic fluxes are focused and oriented on the substantially active surface, and therefore a higher gap magnetic flux density can be obtained as compared with the case of the axial orientation. Even in the case where the orientation direction of the magnetic powder particles in the cross section is the divergent orientation, not only can the decrease in torque be effectively suppressed, but also an improvement in torque can be expected.

As the magnet material of the present invention, both sintered magnets and synthetic resin magnets can be used. For example, as the magnetic powder in the sintered magnet and the synthetic resin magnet, any of the known magnet powders such as ferrite, alnico, samarium-cobalt, and neodymium-iron-boron can be used. Also, the average particle size of the magnetic powder particles can be used within a known range. For example, it is generally 1.5 μm for ferrites and 10 to 50 μm for rare earths.

Conventionally known synthetic resins can also be used. For example, polyamide-based synthetic resins such as polyamide 12 and polyamide 6, polyvinyl chloride, vinyl acetate copolymer thereof, homo- or copolymerized vinyl-based synthetic resins such as MMA, PS, PPS, PE, PP, and urethane,
Silicone, polycarbonate, PBT, PET, PE
EK, CPE, Hypalon, Neoprene, SBR, NB
A synthetic resin such as R or a thermosetting synthetic resin such as an epoxy-based or phenol-based resin can be used. Further, the mixing ratio of the magnetic powder and the synthetic resin as the binder depends on the application, but generally it is desirable to set the magnetic powder to 40 to 70 vol%. In addition, it goes without saying that appropriate amounts of conventionally used plasticizers, lubricants, antioxidants, surface treatment agents and the like can be used according to the purpose.

Next, a magnetic circuit device of a magnetic field orientation molding die according to the present invention will be described. 5, 6, and 7,
FIG. 8 schematically shows a preferred example of a magnetic circuit device of an injection mold suitable for use in manufacturing a cylindrical magnet. FIG.
6 is a transverse cross section of the product, and FIG.
Shows the divergent type at both ends. 7 and 8 are cross sections in the longitudinal direction. FIG. 7 shows a simple focusing orientation, and FIG. 8 shows a side focusing orientation at both ends. In the figure, reference numeral 1 denotes a cavity provided in the die 2, 3 denotes a main pole, 4 denotes an intermediate magnetic pole, 5 denotes a counter electrode, 6 denotes a yoke, 7 denotes an exciting coil, and 8 denotes an auxiliary magnetic pole.

The magnet of the present invention can be manufactured by using a mold as shown in the cross section shown in FIGS. 5 and 6, while the longitudinal section is shown in FIGS. That is, for example, when a cylindrical magnet according to the present invention is manufactured by using an injection mold that is a combination of FIGS. 5 and 7, the synthetic resin magnet material introduced into the cylindrical cavity 1 is in a softened state. When a magnetic field is applied to the magnet material, the lines of magnetic force are applied to the intermediate magnetic pole 4 so as to converge from the outer periphery of the one working surface region to the central region inside the working surface in the longitudinal section of the cavity 1. Then, the light is transmitted so as to diverge from the intermediate magnetic pole 4 toward the outer periphery of the other working surface area, and in the cross section, is transmitted from the outer circumference of the working surface area to the intermediate magnetic pole 4 so as to diverge inside the working surface. Then, the light passes through this intermediate magnetic pole 4 so as to converge toward the outer circumference of the arc of the other working surface region, so that the axis of easy magnetization of the magnetic powder particles in the magnet material is oriented along the direction of the magnetic field lines. Result, cross-section FIG. 1 (c), the longitudinal section is of the converging orientation becomes cylindrical magnets as shown in FIG. 1 (b) is obtained.

Here, from the viewpoint of the mold magnetic circuit, FIGS.
As shown in FIGS. 7 and 8, the width of the intermediate magnetic pole 4 is made wider than the width of the main pole 3 and the counter electrode 5 in the cross section, and the width of the intermediate magnetic pole 4 in the longitudinal section in which the magnetic flux is to be reduced is as shown in FIGS. It is important to make the width of the magnetic pole 4 narrower than the width of the main pole 3 and the counter electrode 5, and by adopting such a mechanism, the axis of easy magnetization of the magnetic powder particles is oriented in a desired direction. As a result, in the magnet of the present invention, the axis of easy magnetization of the magnetic powder particles is as shown in FIGS. 1 (c) and 1 (d) in the cross section and in FIGS. 1 (b) and 1 (c) in the longitudinal direction. The orientation is as follows.

The main pole 3, intermediate pole 4, counter pole 5, yoke 7 and auxiliary pole 8 are carbon steel such as S55C, S50C and S40C, die steel such as SKD11 and SKD61 and pamenjur,
A ferromagnetic material such as pure iron is used, while a non-magnetic material such as stainless steel, copper beryllium alloy, high manganese steel, bronze, brass and non-magnetic super steel N-7 is used as the die 2. As the molding method in a magnetic field, magnetic field orientation injection molding, magnetic field orientation compression molding, and magnetic field orientation RIM molding are suitable. In particular, in the case of the combination of FIGS. 1C and 1D and FIG. 1A, extrusion molding can be used. Further, in the case of using rare earth magnetic powder, it is desirable to apply a pulsed high magnetic field in advance or immediately after introducing the magnetic powder into the cavity, and to perform a pretreatment for making the magnetic moment uniform.

[0019]

Embodiment 1 The horizontal direction shown in FIGS. 5, 6, 9 (b) and 10 (b) and the longitudinal direction shown in FIGS. 7, 8, 9 (a) and 10 (a) Using a mold configured by combining the cross sections, a cylindrical magnet having the dimensions shown in FIG. 11 was manufactured under the following conditions. Here, the working surface angle (θ ₁ ) in the cross section is 120
°. The convergence angle in the cross section of the magnetic powder particles is
X _A is the entire focusing as shown in FIG. 11 (c), also the end portions converging as shown in FIG. (D), defined both ends and X _B. On the other hand, in the longitudinal direction, FIG.
In the case of the simple focusing orientation as shown in (b), Y, and in the case of the both-sides side focusing orientation as shown in FIG.
The side surface convergence rate Z was defined as Z (= (ab) / a × 100%).

The motor torque was measured as shown in FIG. 3 or FIG. 4 for the magnet of the present invention, and as shown in FIG. 2 for the conventional magnet. At this time, as shown in FIG. 12, a rotor having three magnetic poles and a magnetic pole angle of 60 ° was used, and the magnetic pole width was 70% of the magnet width.

Raw material magnetic powder A: ferrite magnetic powder (magnet plumbite-based strontium-based ferrite having an average particle diameter of 1.5 μm) Magnetic powder B: samarium-cobalt magnetic powder (2-17 based; average particle diameter of 15 μm)

• Formulation A (Plamag formulation) Magnetic powder: 63 vol% Polyamide 12: 36 vol% Aminosilane A-1100: 1 vol% Formulation B (sintered orientation) Magnetic powder: 50 wt% Water: 50 wt%

Molding method A: Plamag injection molding conditions Pellet compounding used: Compounding A Molding machine: Magnetic-field oriented injection molding machine with a built-in coil Injection cylinder temperature: 300 ° C. Mold temperature: 100 ° C. Injection pressure: 1500 kg / cm ² Excitation time : 15 seconds Cooling time: 20 seconds Injection cycle: 40 seconds ・ Molding method B: Sintered magnet preparation conditions Slurry used: Compounding B Molding machine: Coil-mounted magnetic orientation compression molding machine Molding temperature: 20 ° C Firing temperature: 1250 ° C

・ Hall element 70 μm square gallium-arsenic used ・ Gauss meter Gauss meter used

Table 1, Table 2, Table 3 and Table 4 show the results of measurement of the surface magnetic flux density and motor detent torque on the effective working surface of the two-pole cylindrical magnet thus obtained, together with the evaluation of the cogging phenomenon.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

As is clear from the table, according to the present invention, the orientation direction of the magnetic powder particles in the two-pole cylindrical magnet is focused on the central region of the inner working surface in the longitudinal section and at least both ends in the transverse section. By diverging the vicinity of the portion to the working surface side, it is possible to effectively prevent the occurrence of cogging after the torque is reduced, but rather improved.

[0031]

Thus, according to the present invention, the magnetic powder particles in the cylindrical magnet material are effectively focused and oriented in the central section of the inner working surface in the longitudinal section, while at least near both ends in the transverse section. Can be dissipated to the working surface side, so that the change in the gap magnetic flux density at the boundary of the stator magnetic field can be reduced without lowering the surface magnetic field on the effective working surface after the magnetization, and thus the motor torque can be reduced. The occurrence of cogging can be prevented without lowering.

[Brief description of the drawings]

FIG. 1 is a diagram showing an orientation state of an axis of easy magnetization of magnetic powder particles in a transverse section and a longitudinal section of a cylindrical magnet.

FIG. 2 is a sectional view of a motor incorporating a conventional cylindrical magnet.

FIG. 3 is a sectional view of a motor incorporating a cylindrical magnet according to the present invention.

FIG. 4 is a cross-sectional view of a motor incorporating another cylindrical magnet according to the present invention.

FIG. 5 is a schematic view of a magnetic-field-oriented molding die having a magnetic circuit device suitable for use in manufacturing a cylindrical magnet having a divergent orientation in its entire cross section.

FIG. 6 is a schematic view of a magnetic-field-oriented molding die provided with a magnetic circuit device suitable for use in manufacturing a cylindrical magnet having a cross section having a divergent orientation at both ends.

FIG. 7 is a schematic view of a magnetic-field-oriented molding die provided with a magnetic circuit device suitable for use in manufacturing a cylindrical magnet having a longitudinal section having a simple focusing orientation.

FIG. 8 is a schematic view of a magnetic field orientation molding die having a magnetic circuit device suitable for use in manufacturing a cylindrical magnet whose longitudinal cross section has a side-side converging orientation.

FIG. 9 is a schematic diagram of a magnetic field orientation molding die including a magnetic circuit device used for manufacturing a conventional cylindrical magnet having an axial orientation.

FIG. 10 is a schematic diagram of a magnetic-field-oriented molding die including a magnetic circuit device used for manufacturing a conventional cylindrical magnet having a radial orientation.

FIG. 11 is a diagram showing dimensions of a cylindrical magnet produced in an example and an orientation state of an axis of easy magnetization of magnetic powder particles.

FIG. 12 is a schematic diagram of a motor for measuring a motor torque.

[Description of Signs] 1 Cavity 2 Die 3 Main pole 4 Intermediate pole 5 Counter pole 6 Yoke 7 Excitation coil 8 Auxiliary pole 9 Bearing 10 Washer 11 Leaf spring 12 Brush 13 Cylindrical magnet 14 Rotor pole 15 Rotor excitation coil 16 Shaft 17 Ferromagnetic Body case

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Kikuchi 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corporation Research and Development Headquarters (72) Inventor Akira Yasuda 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01F 7/02

Claims (1)

(57) [Claims] 1. A cylindrical magnet having two opposing regions of an inner peripheral surface of a cylinder having an O-shaped cross section as an active surface, wherein an orientation direction of an axis of easy magnetization of magnetic powder particles of the magnet is: In the working surface region of the cross section of the magnet, at least the vicinity of both ends is focused on the non-working surface side of the magnet, and is focused on the central region of the inner working surface in the longitudinal section including the working surface and the axis of the magnet. Two-pole cylindrical magnet.