JP2001045699A - Motor and electronic apparatus using the motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent splashes of magnetic fluid and operate a motor based on the stable lubricating operation with a magnetic fluid, when a magnetic fluid is used as a bearing oil. SOLUTION: A motor 10 comprises a rotor 20 having a shaft, bearings (a first metal bearing 90, a second metal bearing 92) including a magnetic fluid as the bearing oil for rotatably supporting the shaft and a magnet 80 for magnetically attracting the magnetic fluid for retaining the magnetic fluid of the bearing to the bearing. Moreover, a stator 22 is also provided to cause the rotor 20 to rotate about the shaft with mutual magnetic effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor and an electronic device having the motor.

[0002]

2. Description of the Related Art For example, electronic equipment such as a portable computer is provided with a fan motor for cooling the inside. In order to reduce the thickness of a computer housing, there is a demand for reducing the axial dimension of this type of motor. FIG. 9 shows the structure of a conventional fan motor.
This fan motor comprises a rotor 1000 and a stator 100
1, and a shaft 1002 of the rotor 1000 is rotatably supported by a metal bearing 1003 of the stator 1001. Rotor case 10 of rotor 1000
04 is provided with an impeller 1005, and a driving main magnet 1 is provided inside the rotor case 1004.
006 is provided. The stator 1001 has a stator core 1007, on which a coil is provided. By energizing the coil in a predetermined pattern, the rotor 1000 rotates continuously about the shaft 1002 with respect to the stator 1001 by magnetic interaction between the coil and the main magnet 1006.

[0003]

However, in this type of thin fan motor, when the axial length L of the support 1008 is, for example, about 2.7 mm, the axial length L1 of the metal bearing 1003 is reduced. Very small, 1.8 mm. This causes the following problem. When the metal bearing 1003 is pressed into the support 1008,
It is difficult to keep the inner diameter of the metal bearing 1003 uniform due to uneven stress. As a result, the metal bearing 1003
Optimal clearance between the shaft 1002 and
4 μm clearance cannot be maintained,
The mechanical inconvenience during rotation of the rotor 1000 and the force in the thrust direction due to the inclination increase, and noise and the like occur when the rotor 1000 rotates.

Although the axial dimension L of the support 1008 is small as described above in order to make the fan motor thinner, if the structure in which the metal bearing 1003 contains the bearing oil is adopted, the scattering of the bearing oil is reduced. There is also a problem that a bearing oil cannot be scattered from the metal bearing 1003 when the rotor 1000 rotates, because a structure for preventing the rotation cannot be adopted. Therefore, the present invention solves the above-described problems, and when using a magnetic fluid as the bearing oil, reliably prevents the scattering of the magnetic fluid and operates the motor based on a stable lubrication operation by the magnetic fluid and an electronic apparatus including the motor. It is intended to provide.

[0005]

According to a first aspect of the present invention, there is provided a rotor having a shaft, a bearing portion including a magnetic fluid as bearing oil for rotatably supporting the shaft, and the magnetic member of the bearing portion. A magnet that magnetically attracts the magnetic fluid to retain the fluid in the bearing portion, and a stator that rotates the rotor about the shaft by magnetic interaction. It is a motor. In claim 1, the rotor has a shaft. The stator has a bearing containing a magnetic fluid as bearing oil to rotatably support the shaft of the rotor. In addition, this stator has a magnet for magnetically attracting the magnetic fluid in order to retain the magnetic fluid in the bearing portion to the bearing portion. Accordingly, the magnetic fluid is prevented from scattering when the rotor rotates, and the rotor can be smoothly rotated with respect to the stator while exhibiting a stable lubricating operation by the magnetic fluid.

According to a second aspect of the present invention, in the motor according to the first aspect, the bearing portion includes a first metal bearing and a second metal bearing.
A metal bearing is provided, and the magnet is arranged between the first metal bearing and the second metal bearing. In the second aspect, the first metal bearing and the second metal bearing of the bearing portion are provided.
By arranging magnets between metal bearings,
Since the first metal bearing and the second metal bearing are arranged at a predetermined interval, the first metal bearing and the second metal bearing are arranged at a predetermined interval.
The metal bearing can stably and rotatably hold the shaft of the rotor.

According to a third aspect of the present invention, in the motor according to the first aspect, the bearing portion has a bearing, and the magnet is built in the bearing.

According to a fourth aspect of the present invention, in the motor according to the first aspect, the inner peripheral surface of the bearing portion comes into surface contact with the outer peripheral surface of the shaft via the magnetic fluid.

According to a fifth aspect of the present invention, in the motor according to the first aspect, the inner peripheral surface of the bearing portion has a groove for generating dynamic pressure by the magnetic fluid when the shaft rotates.

According to a sixth aspect of the present invention, there is provided an electronic apparatus including a motor, wherein the motor includes a rotor having a shaft, and a bearing portion including a magnetic fluid as bearing oil for rotatably supporting the shaft. A magnet that magnetically attracts the magnetic fluid to retain the magnetic fluid of the bearing portion on the bearing portion, and a stator that rotates the rotor about the shaft by magnetic interaction. An electronic device including a motor characterized by including the motor. In claim 6, the rotor has a shaft. The stator has a bearing containing a magnetic fluid as bearing oil to rotatably support the shaft of the rotor. In addition, this stator has a magnet for magnetically attracting the magnetic fluid in order to retain the magnetic fluid in the bearing portion to the bearing portion. Accordingly, the magnetic fluid is prevented from scattering when the rotor rotates, and the rotor can be smoothly rotated with respect to the stator while exhibiting a stable lubricating operation by the magnetic fluid.

According to a seventh aspect of the present invention, in the electronic device provided with the motor according to the sixth aspect, the bearing portion has a first metal bearing and a second metal bearing, and the magnet is provided with the first metal bearing. And the second metal bearing.

According to an eighth aspect of the present invention, in the electronic device provided with the motor according to the sixth aspect, the bearing portion has a bearing, and the magnet is built in the bearing.

According to a ninth aspect of the present invention, in the electronic device provided with the motor according to the sixth aspect, an inner peripheral surface of the bearing portion is in surface contact with an outer peripheral surface of the shaft via the magnetic fluid.

According to a tenth aspect of the present invention, in the electronic device provided with the motor according to the sixth aspect, a groove for generating a dynamic pressure by the magnetic fluid when the shaft rotates is formed on an inner peripheral surface of the bearing portion. Have.

According to an eleventh aspect of the present invention, in the electronic equipment provided with the motor according to the sixth aspect, the motor is a fan motor, and the rotor has an impeller.

According to a twelfth aspect of the present invention, in the electronic device provided with the motor according to the eleventh aspect, the motor is disposed in a housing of the electronic device, and the motor has a housing having heat dissipation. According to the twelfth aspect, the heat in the housing of the electronic device can be released to the outside by rotating the rotor through the housing having heat dissipation.

According to a thirteenth aspect of the present invention, in the electronic device provided with the motor according to the twelfth aspect, the housing forms a part of the stator of the motor.

[0018]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a portable computer as a preferred embodiment of an electronic apparatus having a motor according to the present invention. The computer 1 shown in FIG. 1 has a display unit 2 and a main body 3, and the display unit 2 is supported on the main body 3 by a connecting unit 4 so as to be openable and closable. The main body 3 has a keyboard 5 and a motor 10.

FIG. 2 shows the motor 1 taken along the line AA in FIG.
FIG. 3 is a cross-sectional view illustrating a housing 12 of the main body 3 and the main body 3. The motor 10 is used as a fan motor for cooling the inside of the housing 12 of the main body 3. The motor 10 has a rotor 20 and a stator 22. The motor 10 is arranged in the housing 12 and cools the inside of the housing 12 by discharging warm air in the housing 12 to the outside along the direction of the arrow R1 to the direction R2.

As shown in FIG. 2, a circuit board 90 is disposed in the housing 12, for example.
Is mounted with an electronic component 92 that generates heat during operation such as a CPU (Central Processing Unit). FIG. 3 shows FIG.
The structure of the motor 10 of FIG. Motor 10
Has the rotor 20 and the stator 22 as described above. The rotor 20 has a rotor case 29, a shaft 28, a main magnet 30, and an impeller 31. The rotor case 29 is made of, for example, a disk by using a cold-rolled steel plate, and the upper end of the shaft 28 is fixed to the center hole 29A of the rotor case 29 by press fitting. The axis 28 is
For example, it is made of SUS (stainless steel).
As the main magnet 30, for example, a plastic magnet can be adopted, and the N pole and the S pole are multi-pole magnetized. A plurality of impellers 31
9 are fixed to the outer peripheral surface at equal intervals. The impeller 31 is made of, for example, ABS (acrylonitrile butadiene styrene) resin.

The stator 22 includes a housing 41, a bearing unit assembly 42, a Hall element 45, a plate 53,
It has a housing base 52, a stator core 54 and the like. The housing 41 is made of, for example, aluminum die-cast, and houses the rotor 20. Housing base 5
2 is made of, for example, aluminum die-cast
3 is made of, for example, SUS. The plate 53 is connected to the housing 41 via the housing base 52.
Are fixed using a plurality of screws 60.

The rotor 20 is accommodated in the plate 53 and the housing 41. By forming the housing 41 and the housing base 52 by, for example, aluminum die-casting having excellent heat dissipation, the housing 41 transmits heat in the housing 12 of FIG. Can be released to the outside by the rotation of. For this purpose, the electronic components 9 of the circuit board 90 are
2 is disposed in direct contact with the housing 41, and heat generated when the electronic component 92 operates is transmitted to the air in the housing 41 through the housing 41, so that the rotor 20 Heat can be released in the direction of R2.

The Hall element 45 is an element for detecting the rotation angle and the like of the rotor 20 by magnetically detecting the N pole and the S pole of the main magnet 30 of the rotor 20. Can be sent. The stator core 54 is formed, for example, by stacking silicon steel plates, and a coil 70 is wound around the stator core 54. When the coil 70 is energized from the circuit board 90 side, the magnetic field generated by the coil 70 and the magnetic field of the main magnet 30 magnetically interact, and the rotor 20 rotates continuously around the shaft 28 with respect to the stator 22. I do.

Next, the bearing unit assembly 42 of the stator 22 shown in FIG. 3 will be described. The bearing unit assembly 42 includes a substantially cylindrical support 75, a bearing 78, a magnet 80, a thrust receiver 82, and a thrust holder 84, as shown in an enlarged manner in FIG. The support 75 is made of a non-magnetic material such as brass or aluminum die cast, and a thrust holder 84 is fixed to the lower portion of the support 75 by press fitting. The thrust holder 84 supports the thrust receiver 82. The thrust receiver 82 rotatably supports the lower end of the shaft 28. The thrust holder 84 is made of, for example, brass, and the thrust receiver 82 is made of, for example, a resin such as so-called nylon. The support 75 is fixed to the hole 41A of the housing 41 by press fitting.

The bearing 78 of FIG. 4 has a first metal bearing 90 and a second metal bearing 92. The first metal bearing 90 and the second metal bearing 92 are ring-shaped bearings, and are made of, for example, an iron-based material. The first metal bearing 90 and the second metal bearing 92 contain magnetic fluid oil as bearing oil. This magnetic fluid oil is also called a magnetic fluid, and is obtained by processing a magnetic powder into a size of, for example, 0.001 μm or less and mixing it with a predetermined base oil (for example, a synthetic ester) as necessary. . For this reason, this magnetic fluid oil has a property of staying at a certain place according to the magnetism when the magnet 80 is brought close.

The first metal bearing 90 and the second metal bearing 92 are also called an oil-impregnated bearing, and the shaft 28 is smoothly rotated by the first metal bearing 90 and the second metal bearing 92 via magnetic fluid oil. Can be supported. The inner diameters of the first metal bearing 90 and the second metal bearing 92 are machined to a predetermined value.
0 and the inner diameter after the second metal bearing 92 is pressed into the support 75 is, for example, 1.999 mm,
The inner diameter is finished with an error of about +0.5 μm. Such a first metal bearing 90 and a second metal bearing 92
The shaft 28 is inserted in the inside. The outer diameter of the shaft 28 is, for example, 1.995 mm ± 1.5 μm. Axis 2
Numeral 8 rotates smoothly through the magnetic fluid oil in such a small gap between the first metal bearing 90 and the second metal bearing 92.

As the magnet 80, for example, a plastic magnet can be used, and is formed in a ring shape. The magnet 80 is disposed between the first metal bearing 90 and the second metal bearing 92. However, the inner diameter D of the magnet 80 is different from that of the first metal bearing 90 and the second metal bearing 90.
It is set larger than the inner diameter of the metal bearing 92,
The inner peripheral surface of the magnet 80 does not contact the outer peripheral surface of the shaft 28. By arranging the magnet 80 between the first metal bearing 90 and the second metal bearing 92 in this manner, as a result, the first metal bearing 90 and the second metal bearing 92 are spaced apart from each other by a predetermined distance. Therefore, the first metal bearing 90 and the second metal bearing 92 can stably and rotatably support the shaft 28 at an interval.

The plate 53 shown in FIG. 3 is provided to prevent the impeller 31 of the rotor 20 from dropping upward in the axial direction. The axial thickness S of the motor 10 in FIG. 3 is set to, for example, 4.1 mm, and is a very thin motor. The impeller 31 is formed and fixed to the outer peripheral surface of the rotor case 29. The main magnet 30 is desirably fixed to the inner surface of the rotor case 29 by bonding. The stator core 54 of the stator 22 is, for example, a silicon steel plate divided into four poles and bonded and fixed. Each pole of the stator core 54 has a coil 70. The coil 70 is wound by a predetermined number of turns, and the stator core 54 is mounted on the outer peripheral surface of the support 75 by press fitting. As shown in FIG. 2, the plate 53 is preferably provided with a plurality of holes 53A. The housing 41 has a hole 41A. When the impeller 31 of the rotor 20 rotates, the housing 1
The air in 2 is supplied into the plate 53 through the hole 53A.
In the direction of R2, and is discharged to the outside of the housing 12 along the direction of R2 through the hole 41A.

Next, an operation example of the computer 1 having the above-described motor will be described. When the coil 70 shown in FIG. 3 is energized in a predetermined pattern, the magnetic field generated by the coil 70 and the magnetic field generated by the main magnet 30 interact magnetically, and the rotor 20 moves about the shaft 28 relative to the stator 22. As continuous rotation. Thereby, the impeller 31 takes in the air in the housing 12 in the direction R1, and discharges the air to the outside along the direction R2 through the hole 41A. In such a rotation operation of the rotor 20,
First metal bearing 90 and second metal bearing 9 shown in FIG.
Since the magnetic fluid oil contained in 2 is interposed between the outer peripheral surfaces of the shaft 28, the shaft 28 can rotate smoothly through the magnetic fluid oil. Moreover, the magnet 80
Magnetically attracts the magnetic fluid oil, the magnetic fluid oil remains on the first metal bearing 90 and the second metal bearing 92 even when the shaft 28 rotates continuously at high speed. Oil does not scatter outside the first metal bearing 90 and the second metal bearing 92. Therefore, the magnetic fluid oil does not scatter and adhere to portions other than the bearing portion 78 of the motor, and the shaft 28 can be stably rotated continuously for a long period of time by the first metal bearing 90 and the second metal bearing 92. .

The magnet 80 is connected to the first metal bearing 9.
Since the first metal bearing 90 and the second metal bearing 92 are interposed between the first metal bearing 90 and the second metal bearing 92, the first metal bearing 90 and the second metal bearing 92 are divided and mounted at intervals.
The shaft 28 can be stably held at the time of rotation by the two positions of the first metal bearing 90 and the second metal bearing 92. In addition, since a small magnet 80 may be set in the bearing portion 78 as magnetic suction means for magnetic fluid oil, the bearing unit 42 can be reduced in size, and the axial thickness S of the motor 10 shown in FIG. Can be.

Next, another embodiment of the motor of the present invention will be described with reference to FIG. The motor bearing unit 42 shown in FIG. 5 has a bearing portion 178, and this bearing portion 178 is constituted by one metal bearing 190. The metal bearing 190 and the magnet 1
The structure of the bearing unit 80 is different from that of the bearing unit 42 of FIG. The metal bearing 190 is impregnated with magnetic fluid oil. In the middle of the metal bearing 190, a ring-shaped magnet 180 is incorporated. The inner diameter D of the ring-shaped magnet 180 is set to be larger than the inner peripheral surface of the metal bearing 190, so that the inner peripheral surface of the magnet 180 does not hit the outer peripheral surface of the shaft 28.

FIG. 6 shows still another embodiment of the motor of the present invention. The bearing 278 in FIG. 6 has one cylindrical metal bearing 290. Near the upper end of the metal bearing 290, a ring-shaped magnet 2 is provided.
80 is built-in. The inner diameter D of the magnet 280 is
The inner diameter of the magnet 280 is set larger than the inner diameter of the metal bearing 290 so that the inner peripheral surface of the magnet 280 does not contact the outer peripheral surface of the shaft 28.

FIG. 7 shows still another embodiment of the motor of the present invention. The bearing portion 378 in FIG. 7 has one metal bearing 390. This metal bearing 3
The magnet 380 is built in the lower part of the 90. The inner diameter D of the magnet 380 is set larger than the inner diameter of the metal bearing 390 so that the inner peripheral surface of the magnet 380 does not hit the shaft 28.

FIG. 8 shows still another embodiment of the motor of the present invention. 8 includes a first metal bearing 490 and a second metal bearing 492. The magnet 80 is disposed between the first metal bearing 490 and the second metal bearing 492. The inner diameter D of the magnet 80 is set to be larger than the respective inner diameters of the first metal bearing 490 and the second metal bearing 492. Thereby, the inner peripheral surface of the magnet 80 is
8 does not hit the inner peripheral surface. The first metal bearing 490 and the second metal bearing 492 can be made using the same material as the embodiment of FIG.
On the inner peripheral surfaces of the metal bearing 490 and the second metal bearing 492, a plurality of grooves 500 as illustrated in FIG. 8 are formed along the inner peripheral surface. The groove 500 is a dynamic pressure groove for generating a dynamic pressure when the shaft 28 rotates, and for example, a so-called herringbone groove can be adopted.

The motor of the present invention is not limited to a fan motor, and can be used, for example, as a so-called spindle motor used when rotating a disk-shaped information recording medium. In this case, the shaft protrudes from the upper surface of the rotor. Further, the motor of the present invention is not limited to a fan motor or a spindle motor, and can be applied to other fields or other fields. The electronic devices are not limited to portable computers, and include, for example, a thin floppy disk drive, a thin hard disk drive, and the like.

[0037]

As described above, according to the present invention,
When a magnetic fluid is used as the bearing oil, scattering of the magnetic fluid can be reliably prevented, and the operation can be performed based on a stable lubrication operation by the magnetic fluid.

[Brief description of the drawings]

FIG. 1 is an exemplary perspective view showing a portable computer as an example of an electronic apparatus including a motor of the present invention.

FIG. 2 is an exemplary cross-sectional view taken along line AA of the portable computer shown in FIG. 1;

FIG. 3 is an enlarged view showing the structure of the motor shown in FIG. 2;

FIG. 4 is an enlarged view showing a structure of a bearing unit of the motor shown in FIG. 3;

FIG. 5 is a diagram showing a structural example of a bearing unit in another embodiment of the motor of the present invention.

FIG. 6 is a diagram showing a structure of a bearing unit in still another embodiment of the motor of the present invention.

FIG. 7 is a diagram showing a structure of a bearing unit in still another embodiment of the motor of the present invention.

FIG. 8 is a diagram showing a structure of a bearing unit in still another embodiment of the motor of the present invention.

FIG. 9 is a diagram showing the structure of a conventional motor.

[Explanation of symbols]

1 ... computer (electronic device with motor), 1
0 ... motor, 20 ... rotor, 22 ... stator, 29 ... rotor case, 30 ... main magnet, 31 ... impeller, 41 ... housing,
42 ... bearing unit assembly, 78 ... bearing part, 80 ... magnet, 90 ... first metal bearing, 92 ... second metal bearing

Claims (13)

[Claims] A rotor having a shaft, a bearing portion containing a magnetic fluid as bearing oil for rotatably supporting the shaft, and a magnetic member for retaining the magnetic fluid of the bearing portion to the bearing portion. A magnet for magnetically attracting a fluid, and a stator for rotating the rotor about the axis by magnetic interaction. 2. The bearing according to claim 1, wherein the bearing has a first metal bearing and a second metal bearing, and the magnet is disposed between the first metal bearing and the second metal bearing. Motor. 3. The motor according to claim 1, wherein the bearing unit has a bearing, and the magnet is built in the bearing. 4. The motor according to claim 1, wherein an inner peripheral surface of the bearing portion comes into surface contact with an outer peripheral surface of the shaft via the magnetic fluid. 5. The motor according to claim 1, wherein an inner peripheral surface of the bearing portion has a groove for generating a dynamic pressure by the magnetic fluid when the shaft rotates. 6. An electronic apparatus including a motor, wherein the motor includes: a rotor having a shaft; a bearing unit including a magnetic fluid as bearing oil for rotatably supporting the shaft; A magnet for magnetically attracting the magnetic fluid to retain the magnetic fluid on the bearing portion, and a stator for rotating the rotor about the shaft by magnetic interaction. Electronic equipment equipped with a motor that performs 7. The bearing according to claim 6, wherein the bearing has a first metal bearing and a second metal bearing, and the magnet is disposed between the first metal bearing and the second metal bearing. Electronic equipment equipped with a motor. 8. An electronic apparatus comprising the motor according to claim 6, wherein the bearing unit has a bearing, and the magnet is built in the bearing. 9. An electronic apparatus comprising the motor according to claim 6, wherein an inner peripheral surface of the bearing portion is in surface contact with an outer peripheral surface of the shaft via the magnetic fluid. 10. An electronic apparatus comprising the motor according to claim 6, wherein an inner peripheral surface of the bearing portion has a groove for generating a dynamic pressure by the magnetic fluid when the shaft rotates. 11. The electronic apparatus according to claim 6, wherein the motor is a fan motor, and the rotor has an impeller. 12. The electronic apparatus according to claim 11, wherein the motor is disposed in a housing of the electronic apparatus, and the motor has a housing having heat dissipation. 13. An electronic apparatus comprising the motor according to claim 12, wherein the housing forms a part of the stator of the motor.