JP2003151823A - Bonded magnet assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonded magnet assembly which is small in size and high in performance. SOLUTION: A cylindrical bonded magnet assembly is composed of a cylindrical member and a sheet magnet which contains magnetically anisotropic R-Fe-N (where, R denotes one or more rare earth elements containing Y and Sm without fail) magnetic powder oriented in the prescribed direction and high-molecular polymer and is mounted on the outer periphery or a part of the inner periphery of the cylindrical member. Provided that the external diameter and thickness of the sheet magnet are represented by D (>=1 mm) and t (>=0.5 mm) respectively, t is so set as to reside in a region surrounded with a straight line represented by a formula, t=(D-0.5)×0.32+0.5, and another straight line represented by a formula, t=0.5. It is preferable that a sheet magnet of thickness 0.5 to 1.5 mm is wound so as to have a curvature radius of 15 mm or above.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an R-Fe-N (where R is one or more rare earth elements including Y and always contains Sm) system magnetic powder exhibiting magnetic anisotropy. The present invention relates to a bonded magnet assembly in which a sheet-shaped magnet bonded by a molecular polymer is mounted on the peripheral surface of a cylindrical body.

[0002]

2. Description of the Related Art Various permanent magnets are used in permanent magnet type rotating machines used in electric components, home electric appliances, information terminal devices, etc. For example, in the field of electric components, mainly from the viewpoint of heat resistance. Ferrite magnets are used, and rare earth magnets typified by Nd-Fe-B magnets are often used in the field of information terminal equipment in terms of magnetic characteristics. Particularly for applications requiring small size and high performance, compression molding using a raw material mixture containing magnetic isotropic rare earth magnet powder containing Nd ₂ Fe ₁₄ B type intermetallic compound as a main phase and a thermosetting resin. Manufactured by N
d-Fe-B isotropic rare earth bonded magnets are often used. This Nd-Fe-B system rare earth bonded magnet has an advantage that it is easy to use because it is easy to mold and has a degree of freedom of magnetization, but in order to achieve further downsizing and higher performance, SmFe system alloy powder is used. Sm-Fe- produced by nitriding and allowing N to enter the Fe crystal lattice.
The application of N-based bonded magnets is under consideration. This Sm-F
Although the e-N-based bonded magnet is inexpensive and has relatively high magnetic characteristics, magnetic isotropic ones have insufficient magnetic characteristics (for example, about 60 to 64 KJ / m ³ at (BH) max), and therefore magnetic anisotropy. Magnetically anisotropic bonded magnets containing Sm-Fe-N-based magnet powder exhibiting directionality and a high molecular polymer, in which the magnet powder is oriented in a predetermined direction, have been studied.

For example, in Japanese Unexamined Patent Publication No. 2000-124018, Sm-Fe-N type anisotropic particles or anisotropic particles and ferrite particles are mixed with synthetic rubber or thermoplastic synthetic resin, and injection molding is performed. It is disclosed to magnetize. Further, in Japanese Patent Laid-Open No. 2000-195713, Sm-F
It is disclosed that a composition comprising e-N magnetic powder and a resin binder is injection-molded in a mold having a magnetic field strength of 2.5 KOe or more to manufacture a polar anisotropic rare earth bonded magnet. Further, in Japanese Patent Laid-Open No. 2001-115044, a substantially spherical magnetic anisotropic rare earth magnetic powder (for example, Sm-Fe-N magnetic powder) having an average particle diameter of 10 μm or less is contained in a matrix containing an elastomer component and a surfactant. It is disclosed that a magnetic sheet having a width of 20 to 40 cm and a thickness of 1 to 4 mm can be obtained by dispersing and orienting the easy axis of magnetization of magnetic powder in the thickness direction and then magnetizing.

[0004]

Uses of small motors, etc.
Is a bonded magnet with a thin wall, small diameter and high magnetic properties.
Stones are required. Specifically, the outer diameter (D) is 30 mm or less.
Below, wall thickness (t) is 2.5 mm or less, D / t is 3 or more,
Maximum energy product {(BH) max} is 95.52KJ
/ M^ThreeThe above bonded magnets are required. But Naga
Injection molding disclosed in Japanese Patent Laid-Open No. 2000-124018
Even if the magnet body does not contain ferrite particles, the maximum
Energy product {(BH) max} is 87.56KJ / m^Three
I cannot meet this demand. JP 2000-1
Manufactured by injection molding in a magnetic field disclosed in Japanese Patent No. 95713
In the manufacturing method or the manufacturing method of compression molding in a magnetic field,
Obtained a ring magnet with thin wall thickness, small diameter and high magnetic properties.
I can't. For example, Sm-Fe-N-based anisotropic particles
Injection molding or compression molding of raw material kneaded material containing
By doing so, the wall thickness (t) is 2 mm and the outer diameter (D) is 25 mm.
When manufacturing a ring magnet of 103.48 KJ / m^Three
Maximum energy product of, but thinner than that
If this happens, the degree of orientation will decrease, so ring magnets with high magnetic properties
You can't get stones. Sm-Fe-N system anisotropy
Injection molding or compression molding of raw material kneaded material containing particles in a magnetic field
By forming a ring magnet with an outer diameter of 100 mm or less
When manufacturing, the wall thickness is 5 mm and the height is 1 to 20 mm.
For dimensions, 95.52 KJ / m ^ThreeMaximum energy product of
, But a ring magnet with a wall thickness of 4 mm or less is manufactured.
31.84 to 63.68 KJ / m^ThreeMaximum of
Only the energy product can be obtained.

Since the magnet sheet disclosed in Japanese Patent Laid-Open No. 2001-115044 has flexibility, it can be incorporated in a motor (for example, inside a motor case).
However, since this magnet sheet contains a large amount of magnetic anisotropic rare earth magnetic powder (up to about 95% by mass) and is strong, even a magnet sheet having flexibility is related to the size of the motor. In some cases, it may not be possible to wind in a cylindrical shape. On the other hand, if it is thin, it may be wound in a cylindrical shape, but the magnetic characteristics deteriorate, so there is the problem that the weight of the motor cannot be reduced. Therefore, the object of the present invention is to
A small and lightweight bonded magnet assembly having high magnetic properties is provided.

[0006]

In order to achieve the above object, a bonded magnet assembly of the present invention comprises a cylindrical member and a magnetic anisotropic member mounted on at least a part of its outer peripheral surface or inner peripheral surface. Containing R—Fe—N (where R is one or more rare earth elements including Y and always containing Sm) exhibiting properties and a high molecular weight polymer, and the magnet powder is oriented in a predetermined direction. When the outer diameter of the sheet-shaped magnet is D (1 mm or more) and the thickness is t (0.5 mm or more), t is t = (D-0.5) × It is characterized by being selected so as to exist in a region surrounded by a straight line represented by 0.32 + 0.5 and a straight line represented by t = 0.5. In the bonded magnet assembly of the present invention, it is preferable that the sheet-shaped magnet is mounted over the entire outer peripheral surface or the inner peripheral surface of the cylindrical member. In the bonded magnet assembly of the present invention, it is preferable that the sheet-shaped magnet is oriented in the thickness direction. In the bonded magnet assembly of the present invention, the sheet-shaped magnet may be wound in multiple layers on the outer peripheral surface or the inner peripheral surface of the cylindrical member. The bonded magnet assembly of the present invention has a wall thickness (t) of 0.5 to 2.5.
mm sheet magnet with an outer diameter (D) of 30 mm or less, D /
It is preferable to wind so that t becomes 3.3 to 48. According to the present invention, since the bonded magnet assembly has the ratio of the outer diameter and the thickness of the sheet-shaped magnet within a specific range and has high magnetic characteristics, a compact and high-performance rotating machine can be obtained.

[0007]

The details of the present invention will be described below with reference to the accompanying drawings.
Explain. FIG. 1 shows a sheet magnet used in the present invention.
It is sectional drawing of the apparatus which manufactures. In the figure, 1 is a magnet
Sheet magnet with stone powder oriented in the thickness direction, 20 is pressed
A molding machine, 21 is a mold, 22 is a magnetic field generation coil 23
An orienting device having a wound yoke 24. Sheet
The magnet 1 is a mixture of raw materials containing magnet powder and a polymer.
Compound by heating and kneading and crushing
Make a compound and add this compound to a screw tie, for example.
1kg / m ^TwoPressure of
After being extruded from the mold 21 by using a
Set at stand 24 while heating to 100-200 ° C
795.7-1591.4 KA / m parallel magnetic field (of magnetic flux
The flow is obtained by applying
It In addition, the above sheet-shaped magnet is a substitute for the above-mentioned extrusion molding.
, Melt the compound, roll with a pair of rolls, and exit
Also obtained by orienting magnet powder in the thickness direction in the vicinity.
To be The present invention is limited to the sheet-like magnet shown in FIG.
However, the surface of the magnet powder is oriented as shown in FIG.
It is possible to use a sheet-shaped magnet 2 having a directionality. This sheet
The magnet 2 is an injection type magnet provided with an orienting device around the molding space.
It can be manufactured by a molding machine or a compression molding machine, but has magnetic properties
From the above point, it is desirable to manufacture by the same method as above.

The sheet magnet 1 (2) has a thin wall.
High magnetic properties even with {wall thickness (t) of 0.5 to 2.5 mm}
(95.12 KJ / m^ThreeMore than)
Therefore, Sm-Fe-N having magnetic anisotropy as magnet powder
A system magnet powder is used. The particle size distribution of magnet powder is small
If it is too large, oxidization and processing deterioration easily occur during grinding.
Since the moldability is reduced, the range of 0.5 to 30 μm is preferable.
Good Sm-Fe-N magnet powder having magnetic anisotropy,
Then R_αT_{100-α- β}N_β(R is rare earth containing Y
T, which is one or more of the group elements and always contains Sm
Is Fe or Fe and Co), and α and β are atomic% respectively.
, Α = 5-20, β = 5-30)
However, the main phase of the magnet is, for example, Th_TwoZn₁₇Mold, Th _TwoNi
₁₇Mold, TbCu₇Magnets with crystalline structure of any of the types
Stone powder is preferred. Coercive force is large when α is less than 5%
The saturation magnetization becomes smaller when the content exceeds 20%, and the residual
The residual magnetic flux density is significantly reduced. The ratio of Sm to R
The larger the ratio (atomic%), the larger the coercive force.
To obtain a coercive force of 7.5 KA / m (5 KOe) or more
Is required to be 50% or more, preferably 90% or more
However, R may contain only Sm. N is 5%
If less than, magnetic anisotropy becomes small and coercive force greatly decreases.
However, when it exceeds 30%, the saturation magnetization becomes small. Also Sm
And / or part of Fe is Co, Ni, Ti, Cr, M
n, Zn, Cu, Zr, Nb, Mo, Ta, W, Ru,
One or more of Rh, Hf, Re, Os and Ir
You may substitute by the above element. However, substitution amount (atomic%)
Is too small, the saturation magnetization becomes small, so Sm and Fe
Of about 10% or less is desirable. However, Co
Has a small decrease in saturation magnetization even if its substitution amount is large,
e Curie point within the range of 0.1-70%
Can be increased. Part of N is greatly reduced by C, P, S
It may be replaced by i, S, Al, etc.
Since the magnetic force decreases, it is desirable that it is 10% or less of N.
Good The above-mentioned magnet powder is made of, for example, an R-Fe alloy.
Grind with a lighter, jet mill, etc.
And / or approximately in a reducing atmosphere containing ammonia gas
Hold at a temperature of 300 to 650 ° C for 5 minutes to 30 hours
Nitriding process by, and then pulverizing to a specified particle size
Is obtained by

As the high molecular weight polymer, an elastomer or a thermoplastic resin can be used. As the elastomer, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, nitrile rubber, acrylic rubber or the like can be used. Especially when heat resistance is required,
Ethylene propylene rubber and fluororubber are preferable, and a thermoplastic elastomer composed of a resin component and a rubber component which do not require vulcanization can also be used. As the thermoplastic resin, for example, a vinyl resin such as polyolefin such as polyethylene or polypropylene, a condensation resin such as polyamide, polyester, polyimide or polyether can be used.
When heat resistance is particularly required, (1) crystalline engineering plastics such as polyamide and polyacetal, (2) amorphous engineering plastics such as polycarbonate and modified polyphenylene ether,
(3) Crystalline super engineering plastics such as polyphenylene sulfide, polyether ether ketone, liquid crystalline aromatic polyester, and fluororesin; or (4) Amorphous super engineering plastics such as polysulfone and polyamideimide Two or more kinds may be mixed and used. The high molecular weight polymer is
It is preferably contained in the raw material in the range of 1 to 10% by mass, and more preferably in the range of 1 to 5% by mass. When the content of the high molecular weight polymer is low, the strength of the molded product decreases,
If it is too large, the magnetic properties deteriorate. In the above raw material mixture,
If necessary, a lubricant such as a wax, a fatty acid or a metal salt of stearic acid, or a plasticizer may be added to improve moldability. However, if the addition amount of these is large, the magnetic properties are deteriorated, so a small amount (about 1% or less) is preferable.

The above sheet magnet can be applied to various permanent magnet type rotating machines including a magnet type AC generator, a magnet type synchronous generator, a hysteresis motor and a permanent magnet field DC motor. In particular, in the bonded magnet assembly of the present invention, a sheet magnet having a wall thickness (t) of 0.5 to 1.5 mm has an outer diameter (D) in order to reduce the size and weight of the motor and achieve high motor performance. It is preferable to wind so as to have a thickness of 4 to 30 mm and a D / t of 3.3 to 48. FIG. 3 is a cross-sectional view showing an example of the bonded magnet assembly of the present invention. The bonded magnet assembly 10 shown in FIG. 3A is formed by winding the sheet magnet 11 around the outer peripheral surface of the rotor core 12, and
A plurality of magnetic poles are symmetrically magnetized along the circumferential direction on the surface of the. Bonded magnet assembly 13 shown in FIG.
Is formed by winding the sheet magnet 1 around the outer peripheral surface of the salient pole type rotor core 12. FIG. 3C shows a hysteresis motor rotor, which is formed by winding a sheet-shaped magnet 11 around the inner peripheral surface of a cup-shaped nonmagnetic ring 15 having a shaft 16. Further, the bonded magnet assembly of the present invention is not limited to the sheet magnet wound in a cylindrical shape, and the sheet magnet may be curved into an arc segment shape. For example, as shown in FIG. 4, the rotor core 12 is required. The sheet magnet 11 may be attached only to the magnetic pole portion. Further, as shown in FIG. 5, the surface of the sheet-like magnet 11 may be magnetized by inclining in the length direction, and by winding the sheet-like magnet, a spiral magnetic pole arrangement is obtained, and the magnetic field of the motor is obtained. When the magnet is used, the cogging torque can be reduced. Further, as shown in FIG. 6, the sheet magnet 11 may be wound in a plurality of layers. However, when the sheet-shaped magnet 11 is wound, it is desirable that the sheet-shaped magnet 11 be wound so that the joints 11a of the adjacent layers do not overlap each other, whereby the end faces can be closely attached to each other.

[0011]

Example (Example 1) The particle size distribution is 0.5 to 30 μm,
Sm _9.1 Fe _77. with an average particle size of 2.5 μm _{. 3} N
_A compound consisting of 97 parts by mass of anisotropic magnet powder having a composition of _13.6 and 3 parts by mass of isoprene-based rubber was put into an extrusion molding machine, and the extruded molding was cut to a predetermined length and heated to 170 ° C. Then, while applying a parallel magnetic field of 1193.6 KA / m, a pressure of 9.8 × 10 ⁸ Pa is applied to produce a sheet-shaped magnet. Sheet magnet (width 50m
m, thickness 0.5 to 12 mm) was wound around a shaft having an outer diameter of 1 to 12 mm, and the gap between the sheet and the shaft was measured for each thickness to calculate the wrappable diameter. The wrappable diameter is a dimension when the sheet and the shaft are in close contact with each other and there is substantially no gap. FIG. 7 shows the relationship between the wrappable diameter {(D) mm} and the sheet thickness {(t) mm}. The shaded area in the figure is the winding range, and this range is approximately t
= (D−0.5) × 0.32 + 0.5 and a region surrounded by a straight line represented by t = 0.5. Figure 7
Therefore, the thinner the sheet thickness t is, the smaller the diameter can be wound. For example, when the sheet thickness t is 0.5 mm, the wrappable diameter D is 1 mm or more, and when the sheet thickness t is 2.5 mm. It can be seen that the winding diameter D is 6.7 mm or more.
However, in consideration of easiness of sheet production and assembly of a rotating machine, etc., since the outer diameter to which the present invention is effectively applied is 30 mm or less, the thickness of the sheet-shaped magnet of the present invention is 0.5 to 1.5.
mm is desirable.

(Embodiment 2) The bonded magnet assembly of the present invention can constitute various motors, one example of which is shown in FIG. FIG. 8 is a sectional view of a vibration motor for a pager. A vibration motor 25 shown in the same drawing includes a stator 26 including an outer yoke 27 and a cylindrical field magnet 28 held inside the outer yoke 27, a cup-shaped armature 30, and a rotor shaft 32 having a counterweight 31 fixed to one end. And a coreless rotor 29 including. The cup-shaped armature 30 is connected to a battery power source (not shown) via a leaf spring with brush 33 and a commutator 34, and the rotor shaft 32 is supported by the stator 26 via a bearing 35. According to the above configuration, when the drive current is applied to the cup-shaped armature 30, the counterweight 31 fixed to one end of the rotor shaft 32 is rotated and the runout vibration is generated. The field magnet 28 has a width of 10.0 mm under the same conditions using the same compound as that of the first embodiment.
A sheet having a thickness of 0.5 mm was formed, magnetized with 8 poles, and attached to the inner surface of a stator 26 having an inner diameter of 3.6 mm. Since this vibration motor has a small outer diameter of 10.2 mm and is multi-polarized with 8 poles, a desired rotational driving force can be obtained. That is, according to the bonded magnet assembly of the present invention, it is possible to realize a compact vibration motor for a pager that can generate vibration with low power consumption.

[0013]

As described above, according to the present invention, a compact and high-performance permanent magnet rotating machine can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a sheet-shaped magnet manufacturing apparatus of the present invention.

FIG. 2 is a sectional view of a sheet magnet according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a rotor of a rotating machine according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a rotor of a rotating machine according to another embodiment of the present invention.

FIG. 5 is a sectional view showing a rotor of a rotating machine according to another embodiment of the present invention.

FIG. 6 is a plan view showing a sheet magnet according to another embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a winding diameter and a thickness of a sheet magnet.

FIG. 8 is a sectional view of a vibration motor for a pager including the bonded magnet assembly of the present invention.

[Explanation of symbols]

1, 2, 11: Sheet magnet 10, 13, 14: Magnet assembly 12: Rotor core 15: Non-magnetic ring 16: axis 20: Extruder 21: Mold 22: Orientation device 23: Magnetic field generating coil 24: York 25: Vibration motor 26: Stator 27: Outer yoke 28: Field magnet 29: Coreless rotor 30: Cup-shaped armature 31: Counterweight 32: rotor shaft 33: Leaf spring with brush 34: Commutator 35: Bearing

Claims (7)

[Claims] 1. A cylindrical member and R-Fe exhibiting magnetic anisotropy attached to at least a part of an outer peripheral surface or an inner peripheral surface of the cylindrical member.
A sheet magnet in which -N (where R is one or more rare earth elements including Y and always contains Sm) and a high molecular weight polymer and in which the magnet powder is oriented in a predetermined direction; And the outer diameter of the sheet magnet is D (1 mm or more) and the thickness is t (0.5 mm or more), t is t
= (D−0.5) × 0.32 + 0.5 and a bond magnet selected to exist in a region surrounded by a straight line represented by t = 0.5. Assembly. 2. The bonded magnet assembly according to claim 1, wherein the sheet-shaped magnet is mounted over the entire circumference of the outer peripheral surface or the inner peripheral surface of the cylindrical member. 3. The bonded magnet assembly according to claim 1, wherein the sheet-shaped magnet is oriented in the thickness direction. 4. The bonded magnet assembly according to any one of claims 1 to 3, wherein the surface of the sheet-shaped magnet is magnetized in multiple poles. 5. The bonded magnet assembly according to claim 1, wherein the sheet-shaped magnet is wound in multiple layers on an outer peripheral surface or an inner peripheral surface of the cylindrical member. 6. The sheet-shaped magnet has an outer diameter (D) of 30 m.
The bonded magnet assembly according to claim 1, wherein the bonded magnet assembly has a thickness (t) of 0.5 to 2.5 mm and a D / t of 3.3 to 48. 7. The bonded magnet assembly according to claim 6, wherein the sheet magnet has a height of 1 mm or more.