JP2002178358A - Fixed structure injection-molded magnet and motor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the fixed structure of an injection-molded magnet which uses the magnet advantageous in terms of rust prevention, can be used even when no special rust preventive treatment is applied or only by simply rust preventive treatment, and can prevent the scattering of powder caused by rust even when applied to a high speed rotation electric machine and a motor using the magnet. SOLUTION: In the fixed structure of the injection-molded magnet which bonds/fixes the magnet 10 containing an iron component and is injection-molded to an object to be fixed, the gate cut part 17 of the magnet 10 is positioned on a bonding/fixing surface 16 to the object. The motor uses the injection- molded magnet in which the object of the injection-molded magnet 10 in the fixed structure of the injection-molded magnet is the rotor 11 or stator 6 of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet fixing structure made by injection molding and a motor using the injection molded magnet.

[0002]

2. Description of the Related Art A magnet containing an iron component, for example, a neodymium-iron-boron (Nd-Fe-B) bond magnet is generally prepared by (1) compression molding, (2) extrusion molding, and (3) injection molding. Manufactured. A magnet containing iron, such as the above-mentioned Nd-Fe-B magnet, has the property of being easily rusted. The degree of rust generation depends on the manufacturing method. Compression molded products are easily rusted because the magnet material is exposed. In the case of extrusion molding or injection molding, in order to improve the fluidity of the material at the time of molding, about 40% of the volume is made of a binder made of a resin such as nylon, and the surface of the magnet after molding is covered with the resin. It is hard to rust.

However, in the case of extrusion molding, the product immediately after molding is a long product, and it must be cut to a predetermined length in order to adapt it to a predetermined application such as a motor. . Since there is no resin layer on the cut surface and the magnet material is exposed, there is a disadvantage that rust is easily generated from the cut surface. Also in the case of injection molding, it is necessary to cut and remove the gate portion at the time of molding, and there is a disadvantage that rust easily occurs from the gate cut portion. However, the gate cut portion has a smaller area than the cut surface of the extruded product, and the degree of rust is smaller than that of the extruded product.

[0004] Regardless of the method used, rust is generated, so that rust prevention treatment is generally indispensable. If this is used for a rotating electric machine such as a motor without performing rust prevention treatment, powder generated by rust may enter the gap between the rotor and the stator to increase friction and cause seizure. Rust prevention methods for magnets include (1) plating methods such as electric nickel plating, electroless nickel plating, and zinc plating; (2) painting methods such as spraying, dipping, and electrodeposition; and (3) dipping in rust-preventive oil. There is a simple rust prevention method of forming a chemical conversion film by chromate treatment or the like. The plating method and the painting method are expensive, and the simple rust prevention method is relatively low cost.

[0005]

Considering the state of the prior art, the injection molded magnet has a high content of resin such as nylon, and is hardly rusted because the resin covers magnetic powder. You may be able to use it without doing so. However, the gate portion after injection molding is a place where rust is first generated because the magnetic powder is exposed by cutting. Therefore, only the gate cut portion may be subjected to rust prevention treatment. Further, in the gate cut portion, burrs due to the gate cut easily remain, and when this magnet is applied to a high-speed rotation motor or the like, the burrs are separated by centrifugal force and may damage the rotor and the stator. Therefore, it is necessary to remove cutting burrs at the gate cut portion.

The present invention has been made in view of the above-mentioned problems of the prior art, and uses an injection-molded magnet which is advantageous for rust prevention, and does not require any special rust prevention treatment.
Alternatively, even if rustproofing is performed, it can be used only with simple rustproofing, and even when used for high-speed rotating electric machines,
An object of the present invention is to provide a fixing structure of an injection-molded magnet and a motor using the injection-molded magnet, which can prevent scattering of powder caused by rust.

[0007]

According to the first aspect of the present invention,
A fixing structure of an injection-molded magnet that contains an iron component and adhesively fixes an injection-molded magnet to a fixing target,
The gate cut portion of the magnet is located on a surface to be fixed to the object to be fixed.

According to a second aspect of the present invention, in the first aspect of the invention, the magnet is subjected to a simple rust preventive treatment such as immersion in rust preventive oil or chromate treatment.

According to a third aspect of the present invention, there is provided a motor using an injection-molded magnet, wherein the injection-molded magnet is fixed by a rotor or a stator of the motor in the injection-molded magnet fixing structure according to the first or second aspect. There is a feature.

According to a fourth aspect of the present invention, in the third aspect of the invention, the injection-molded magnet is a partial arc-shaped magnet, and a plurality of partial arc-shaped magnets are arranged so as to form a cylindrical shape. It is characterized by having. According to a fifth aspect of the present invention, in the third aspect of the invention, the injection molded magnet is a cylindrical magnet. The invention according to claim 6 is the invention according to claim 3, wherein the motor is a dynamic pressure motor.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a structure for fixing an injection-molded magnet and a motor using the injection-molded magnet according to the present invention. In FIG. 1, reference numeral 10 denotes an injection molded magnet,
Reference numeral 16 denotes a surface to be fixed to an object to be fixed, and 17 denotes a gate cut portion. The injection molded magnet 10
For example, neodymium-iron-boron (Nd-
Fe-B), wherein the bond magnet is
It is obtained by mixing d-Fe-B and a resin such as nylon as a binder to give fluidity and injection molding the mixture. The injection-molded magnet 10 has a tile-shaped partial arc shape, and the outer surface of the arc is an adhesive fixing surface 1 to be fixed to an object to be fixed.
It is 6. A gate cut portion 17 is provided substantially at the center of the adhesive fixing surface 16.

When the injection-molded magnet 10 is applied to a motor as shown in FIGS. 2 and 3, it is not necessary to rust-prevent it, but it may be rust-proof if necessary. However, as described above, the properties of the injection-molded magnet are such that it is difficult to rust except for the gate cut portion. It suffices to perform the treatment by a simple rust-prevention method that forms

Next, an example in which the injection-molded magnet 10 is applied to a motor will be described with reference to FIGS. The motor shown in FIG. 2 and FIG. 3 is an example of an air dynamic pressure bearing motor for rotating a polygon mirror at high speed. 2 and 3, the motor frame 1 integrally has a columnar shaft 2 at the center. A cylindrical core holder 3 is fixed to the motor frame 1 on the outer peripheral side of the shaft 2 by an appropriate fixing means. A stator core 4 in which cores are laminated is fixed to the outer peripheral side of the core holder 3. The stator core 4 has a plurality of salient poles radially,
A drive coil 5 is wound around each salient pole. The stator core 4 and the drive coil 5 constitute a stator 6 of the motor.

A sleeve 7 is fitted on the outer peripheral side of the shaft 2 of the motor frame 1 on the inner peripheral side of the core holder 3. There is a minute gap between the inner peripheral surface of the sleeve 7 and the outer peripheral surface of the shaft 2, and a dynamic pressure groove is formed on at least one of the inner peripheral surface of the sleeve 7 and the outer peripheral surface of the shaft 2.
The inner peripheral surface of the sleeve 7 and the outer peripheral surface of the shaft 2 constitute a radial air dynamic pressure bearing. There is a gap between the outer peripheral surface of the sleeve 7 and the inner peripheral surface of the core holder 3 that is larger than the clearance of the dynamic pressure bearing. A circular jetty 18 is formed on the outer periphery of the upper end of the shaft 2 by being rounded.
A ring-shaped magnet 19 is fixed to the inner peripheral side of 8.

A step 12 is provided on the outer periphery near the upper end of the sleeve 7.
Are formed. The center hole of the rotary polygon mirror 13 is fitted to the upper end of the sleeve 7, and the rotary polygon mirror 13 is mounted on the step 12. The elastic body 14 and the clamper 15 are stacked on the rotary polygon mirror 13 in this order, and the rotary polygon mirror 13 and the clamper 15 are fixed to the sleeve 7 by screwing the clamper 15 to the sleeve 7. A cylindrical magnet 20 is attached to the clamper 15. A minute gap is formed between the outer peripheral surface of the magnet 20 and the inner peripheral surface of the magnet 19. Further, an axial magnetic attraction repulsion is generated between the magnet 20 and the magnet 19, and a rotating body including the sleeve 7, the rotating polygon mirror 13, and a motor rotor 11 described later is generated by the magnetic attraction repulsion. The magnet 20 and the magnet 19 are magnetized so as to be supported in the thrust direction without contact with the shaft 2 and the stator 6 of the motor. That is, the magnets 19 and 20 constitute a magnetic thrust bearing.

The sleeve 7 integrally has a rotor case 8 at an intermediate portion in the axial direction. The rotor case 8 has a cylindrical peripheral wall, and a rotor magnet 10 is fixed to the inner surface side of the peripheral wall by bonding. The portion including the rotor case 8 and the rotor magnet 10 is the rotor 11 of the motor.
Is composed.

As shown in FIG. 3, the rotor magnet 10
Has a cylindrical shape as a whole, but in this embodiment, the magnet is formed into a cylindrical shape as a whole by arranging in a circumferential direction four magnets 10 each of which is formed by dividing a cylinder into four parts and forming a partial arc. ing. The reason for dividing the rotor magnet 10 is to increase the accuracy of the motor. That is, using a cylindrical magnet like many conventional motors,
When this is fixed to the rotor case, the magnet and the rotor case are deformed or displaced due to the difference in the linear expansion coefficient between them when the temperature fluctuates, so that the accuracy cannot be maintained. In this regard, if the rotor magnet 10 is divided into a plurality of magnets as in the embodiment shown in FIGS. 2 and 3, even if the temperature fluctuates, the magnet and the rotor case are relatively deformed or misaligned. This is because a high-precision motor can be obtained without causing any problem.

As described with reference to FIG. 1, the rotor magnet 10 is an injection-molded magnet. The outer surface of the arc serves as an adhesive fixing surface 16 to be fixed. There is a gate cut portion 17. The adhesive fixing surface 16 serves as an adhesive fixing surface to the inner peripheral surface of the rotor case 8. 2 and 3, reference numeral 9 indicates an adhesive layer between the rotor case 8 and the magnet 10.

As is well known, by controlling the energization of each drive coil 5 in accordance with the rotational position of the rotor magnet 10, the rotor 11 and the rotor 11 and the rotor 11 are integrated by the magnetic attraction and repulsion between the rotor magnet 10 and the stator core 4. The rotating bodies such as the rotating polygon mirror 13 and the sleeve 7 are integrally rotated. Due to the rotation of the sleeve 7, a dynamic pressure is generated in an air dynamic pressure bearing portion formed between the sleeve 7 and the shaft 2, and the sleeve 7 is supported in a radial direction without contact. Further, the sleeve 7 is provided by the thrust magnetic bearing.
Are supported in the thrust direction without contact.

According to the embodiment described above, the magnet 10 is an injection-molded bond magnet containing an iron component, and most of the surface is covered with a binder resin.
It is relatively hard to rust. However, since the magnet material is exposed at the gate cut portion 17, rust starts to be generated from the gate cut portion 17. Therefore, the gate cut part 1
7 is bonded and fixed to the rotor case 8 to be fixed.
No. 6. By bonding and fixing the adhesive fixing surface 16 to the rotor case 8, the gate cut portion 17 is covered with the adhesive layer 9, so that the gate cut portion 17 is prevented from contacting with air and is less likely to rust. Also, when the magnet 10 is used in a high-speed rotating electric machine or the like as in the rotary polygon mirror driving air dynamic pressure motor shown in FIGS. 1 and 2, even if powder caused by rust is generated,
The adhesive layer 9 can prevent the powder from scattering, and can prevent a problem such as seizure caused by the powder entering between the rotor and the stator.

As described above, according to the above-described embodiment, the problem of rust of the magnet 10 is almost eliminated, and rust prevention treatment is hardly necessary. However, rust prevention treatment may be performed to further enhance reliability. In such a case, a simple rust-prevention method, such as immersion in rust-preventive oil or formation of a chemical conversion film by chromate treatment, is sufficient.

In the embodiment shown in FIGS. 2 and 3, the rotor magnet 10 is an injection-molded magnet containing iron, and the gate cut portion is located on the surface to be fixed to the object to be fixed. The technical idea of the present invention may be applied to other magnets, for example, the magnets 19 and 20 constituting the thrust magnetic bearing in the examples of FIGS.

In the embodiment shown in FIGS. 2 and 3, the rotor magnet 10, which is an injection-molded magnet, has a partially arcuate shape obtained by dividing a cylinder. The present invention can be applied not only to the arc-shaped magnet but also to other shapes. One example shown in FIG. 4 is one in which the technical idea of the present invention is applied to a cylindrical magnet 25. In FIG. 4, an outer peripheral surface of a cylindrical magnet 25 is a fixing object, for example, an adhesive fixing surface 26 to a rotor case of a motor.
In addition, there is a gate cut portion 27 that cuts a gate generated during injection molding of the magnet 25.

With respect to the magnet 25 as shown in FIG. 4, the same effect as the above-described magnet fixing structure can be obtained by using the above-mentioned fixing structure. Further, by applying the magnet 25 to a motor, the same effects as those of the motor shown in FIGS. 2 and 3 can be obtained.

When the injection-molded magnet according to the present invention is applied to a motor, it may be used as a rotor magnet or a magnet on the stator side.

[0026]

According to the first aspect of the present invention, since the gate cut portion of the magnet is located on the surface to be fixed to the object to be fixed, the gate cut portion is covered with the adhesive layer, and the gate cut portion is formed by the gate cut portion. Rust can be prevented. Therefore, there is no need to rust-proof the magnet.
Magnets can be used at low cost.

According to the second aspect of the present invention, in the magnet fixing structure according to the first aspect, which has a high rust-preventive effect, a simple rust-preventive treatment such as immersing the magnet in rust-preventive oil or performing chromate treatment. , The generation of rust can be prevented even when used under more severe conditions.

According to the third aspect of the present invention, the object of fixing the injection-molded magnet in the injection-molded magnet fixing structure of the first or second aspect is a motor configured as a rotor or a stator of the motor. In addition to preventing the occurrence of rust in the part, even if rust occurs in the gate cut part, the adhesive layer prevents the rust powder from scattering, and the rust powder is placed between the rotor and stator. Damage such as invading the motor and burning the motor can be prevented. Also,
In the gate cut portion, cutting burrs may be generated, but the cutting burrs can also be sealed in the adhesive layer, so that the cutting burrs enter between the rotor and the stator and burn the motor. Damage can be prevented.

According to a fourth aspect of the present invention, in the third aspect of the invention, the injection molded magnet is a partial arc-shaped magnet, and a plurality of partial arc-shaped magnets are arranged so as to form a cylindrical shape. Therefore, even if there is a difference in the coefficient of linear expansion between the magnet and the rotor or stator of the motor to which the magnet is fixed, it is possible to avoid displacement, deformation, and the like between the magnet and the rotor or stator due to temperature fluctuations. Accuracy can be maintained.

In the case where the motor is a dynamic pressure motor, even if rust is generated at the gate cut portion of the magnet or cutting burrs are generated, the rust powder is generated by the adhesive layer. And the cutting burrs are sealed, so that rust powder and cutting burrs can be prevented from entering the dynamic pressure bearing portion, and the function as the dynamic pressure bearing can be prevented from being hindered. Also, in the case of a dynamic pressure motor, when the rotor rotates at high speed and rust powder or cutting burrs are generated, they are diverged by centrifugal force,
According to the invention as set forth in claim 6, since the rust powder and cutting burrs are sealed in the adhesive layer, it is possible to effectively prevent the function as the dynamic pressure bearing from being impaired also from this point.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a fixing structure of an injection-molded magnet according to the present invention and a magnet applicable to a motor using the injection-molded magnet.

FIG. 2 is a longitudinal sectional view showing an embodiment of a motor using the magnet.

FIG. 3 is a bottom view showing a rotor of the motor.

FIG. 4 is a perspective view showing another example of a fixing structure of the injection molded magnet according to the present invention and a magnet applicable to a motor using the injection molded magnet.

[Explanation of symbols]

 Reference Signs List 6 Stator 9 Adhesive layer 10 Magnet 11 Rotor 16 Adhesive fixing surface 17 Gate cut portion 25 Magnet 26 Adhesive fixing surface 27 Gate cut portion

Claims (6)

[Claims] 1. A fixing structure of an injection-molded magnet for bonding and fixing an injection-molded magnet containing an iron component to an object to be fixed, wherein a gate cut portion of the magnet is located on an adhesive fixing surface to the object to be fixed. A fixed structure for an injection-molded magnet, characterized in that: 2. The fixing structure for an injection-molded magnet according to claim 1, wherein the magnet is subjected to a simple rust prevention treatment such as immersion in rust prevention oil or chromate treatment. 3. A motor using an injection-molded magnet, wherein an object to which the injection-molded magnet is fixed in the structure for fixing an injection-molded magnet according to claim 1 is a rotor or a stator of the motor. motor. 4. The motor according to claim 3, wherein the injection-molded magnet is a partial arc-shaped magnet, and the plurality of partial arc-shaped magnets are arranged so as to form a cylindrical shape. 5. The motor according to claim 3, wherein the injection-molded magnet is a cylindrical magnet. 6. The motor according to claim 3, wherein the motor is a dynamic pressure motor.