JP2000078794A - Electric motor and heat sink device using the same - Google Patents

Abstract

(57) [Problem] To provide an electric motor capable of preventing oil outflow from a bearing portion and a heat sink device using the same. SOLUTION: A cylindrical housing 1 having one end opened.
a, a stator 3 attached to the frame 1, and a sleeve 6 fixed to the housing 1a.
And a shaft 16 rotatably fitted in the sleeve 6 and a rotor 16 provided with a magnet 11 opposed to the stator 3, and a shaft 9 on one of the outer circumferential surface of the shaft 9 and the inner circumferential surface of the sleeve 6. Pressure generating groove formed so as not to penetrate the open side end face of the gap between the sleeve and the sleeve 6, oil held in the dynamic pressure generating groove, and an opening of the housing 1 a on the inner wall of the housing 1 a or the outer periphery of the sleeve 6. It is assumed that the motor has a ventilation groove 20 formed from the bottom to the bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor using a dynamic pressure type fluid bearing and a heat sink device using the same.

[0002]

2. Description of the Related Art FIGS. 4 to 6 show the structure of a conventional heat sink device using a motor of a dynamic pressure type fluid bearing.

FIG. 4 is a sectional view showing a heat sink device according to a conventional example, and FIG. 5 is a sectional view showing a bearing portion of a motor used in the heat sink device of FIG.
FIG. 6 is a view showing a dynamic pressure generating groove in a bearing sleeve of the electric motor of FIG. 5.

[0004] As shown in FIG. 4, a drive circuit board 4 provided with a hall element and the like on a stator 3 around which a coil 2 is wound is provided around a cup-shaped housing 1 a protruding from a concave portion of the frame 1. is set up. The stator 3 is fixed to an outer peripheral portion of the housing 1a, and an insulating sheet 10 is provided between the drive circuit board 4 and the frame 1. A bell mouth 19 for smoothing the flow of air is provided on the outer periphery of the frame 1. The housing 1a is formed in a cup shape, and a thruster 7 made of resin or the like is provided on a bottom surface of the housing 1a. Further, a sleeve 6 is fitted into the housing 1a, and forms a stator unit 15.

[0005] A shaft 9 is integrally formed with the fan 8, and a magnet 11 and a magnet yoke 12 are fixed by bonding or the like so as to face the annular stator 3 to form a rotor 16.

[0006] As shown in FIGS. 5 and 6, the bearing portion is provided on the inner peripheral surface of the sleeve 6 or the outer peripheral surface of the shaft 9 at a position where the sleeve 6 and the shaft 9 face each other by dynamic rolling such as ball rolling. A generation groove 13 is formed. The dynamic pressure generating groove is formed so as to penetrate the end surface on the open side where the shaft 9 is fitted in the sleeve 6. Oil 14 is lubricated into the dynamic pressure generating groove 13 as lubricating oil to
Is composed. Further, the thruster 7 side of the shaft 9 is finished to a spherical surface, and forms a thrust bearing 18 which comes into contact with the thruster 7.

[0007]

However, such a conventional electric motor has the following problems.

In recent years, downsizing has been advanced in electronic devices such as personal computers and home appliances, and accordingly, motors such as heat sink devices and cooling fan motors attached to the electronic devices have been required to be smaller and thinner. ing.

Due to the miniaturization and thinning of such an electric motor, the space of the bearing portion has become very small, and the shaft 9 and the sleeve 6 have to be reduced in size. For this reason, the bearing portion is made small in diameter (2 mm or less). However, it is very difficult to form an oil reservoir or an air reservoir in the bearing portion, particularly in the inner diameter of the sleeve due to processing problems.

Further, the heat generation of electronic devices and the like is increasing due to their high performance and miniaturization. As a result, electric motors used for heat sink devices and cooling fans attached to the electronic devices and the like are in an environment where temperature changes are large. In order to enhance the cooling effect, it is necessary to perform high-speed rotation.

On the other hand, the oil 14 held by the surface tension caused by the gap between the shaft 9 and the sleeve 6 and the pumping force gathered at the center by the dynamic pressure generating groove 13 causes the expansion and contraction of the air in the oil due to the increase in temperature change. However, as described above, the bearing part has a small diameter (2 mm or less), so it is not possible to install an oil reservoir or air reservoir, etc., and to improve the adhesion with the heating element, The bottom surface of the housing is sealed to prevent the oil from flowing out from the bottom surface portion, etc., so that the air escape path is limited to the open end surface of the gap between the shaft 9 and the sleeve 6. .

Therefore, when the air in the oil escapes from the gap between the shaft 9 and the sleeve 6, the oil 14 flows out together with the air through the dynamic pressure generating groove having a larger gap.
This is transmitted through the shaft 9 and the rotor 16 and flows out. As a result, insufficient oil in the bearing, a decrease in the number of revolutions, an increase in the current value, abnormal noise, etc., occur.
Lock occurred and reliability was lost.

Accordingly, an object of the present invention is to provide an electric motor capable of preventing a decrease in reliability due to oil outflow from a bearing during rotation.

Another object of the present invention is to provide a heat sink device having high cooling performance using the above-mentioned electric motor.

[0015]

In order to solve this problem, an electric motor according to the present invention comprises a frame having a cylindrical housing with one end opened, a stator mounted on the frame, and a housing. With a sleeve fitted,
A shaft rotatably fitted in the sleeve, a rotor having a magnet arranged opposite to the stator, oil filled in a gap between the shaft and the sleeve, and an outer circumferential surface of the shaft or an inner circumferential surface of the sleeve. There is a dynamic pressure generating groove formed on one side and holding the oil, and the dynamic pressure generating groove does not penetrate to the opening side.

A ventilation groove extending from the opening of the housing to the bottom surface is formed on the inner wall of the housing or the outer periphery of the sleeve.

This makes it difficult for the air in the oil to escape from the dynamic pressure generating groove which penetrates to the open side of the gap between the sleeve and the rotating shaft, and the oil is ejected together when the air escapes. In addition, since the ventilation groove is formed from the bottom surface of the sleeve, the pressure inside the bearing can be adjusted.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention is directed to a frame provided with a cylindrical housing having one end opened, a stator attached to the frame, and a sleeve fitted in the housing. A shaft rotatably fitted in the sleeve, a rotor having a magnet disposed opposite to the stator, oil filled in a gap between the shaft and the sleeve, an outer peripheral surface of the shaft, or an inner peripheral surface of the sleeve. A dynamic pressure generating groove for holding oil, the dynamic pressure generating groove is a motor characterized by not penetrating the opening side, conventionally, the shaft and the sleeve This has the effect of preventing air from escaping from the dynamic pressure generating groove portion in the larger gap between them and the outflow of oil associated therewith.

According to a second aspect of the present invention, there is provided the electric motor according to the first aspect, wherein a ventilation groove extending from an opening of the housing to a bottom surface is formed on an inner wall of the housing or an outer periphery of the sleeve. This has the effect that the pressure inside the bearing can be adjusted.

According to a third aspect of the present invention, there is provided the electric motor according to any one of the first and second aspects, wherein the dynamic pressure type fluid bearing has a small diameter (2 mm or less). This has the effect that the motor can be downsized.

According to a fourth aspect of the present invention, there is provided a cooling fan motor including the electric motor according to any one of the first to third aspects, wherein a heating element is mounted on a frame of the electric motor. This is a heat sink device capable of conducting heat of the heating element directly to the frame of the electric motor, and has a function of radiating heat, and an air flow generated by a fan efficiently hitting the frame to enhance the heat radiation effect.

According to a fifth aspect of the present invention, a plate-shaped or pin-shaped fin is provided on the frame.
The heat sink device according to any one of the preceding claims, which has a function of enhancing a heat radiation effect by the fins.

According to a sixth aspect of the present invention, there is provided a heat sink device according to the fifth aspect, wherein one or more openings are provided in a side wall of the motor frame. By optimizing the number, it has the effect of directing the flow of air to other heating elements and smoothly exhausting high-temperature air.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

FIG. 1 is a sectional view showing a heat sink device according to an embodiment of the present invention, FIG. 2 is a sectional view showing a bearing portion of a motor used in the heat sink device of FIG. 1, and FIG. It is a figure showing a dynamic pressure generating groove in a bearing sleeve.

The motor according to the present embodiment, including the embodiments described below, is used for a heat sink device for cooling semiconductors. As shown in FIG. Cup-shaped housing 1
A drive circuit board 4 provided with a hall element and the like on a stator 3 around which a coil 2 is wound is provided around a.

Plate-shaped or pin-shaped fins 21 are erected in the concave portion of the frame 1, and openings (not shown) through which an air flow passes are provided on a side wall in a predetermined number and a predetermined size in a predetermined direction. It is provided for.

The bottom of the frame 1 on which the housing 1a is not provided has a flat area to which a heating element such as a semiconductor element can be attached.

The stator 3 is fixed to the outer periphery of the housing 1a, and an insulating sheet 10 is provided between the drive circuit board 4 and the frame 1. A bell mouth 19 for smoothing the flow of air is provided on the outer periphery of the frame 1. The housing 1a is formed in a cup shape, and a thruster 7 made of resin or the like is provided on a bottom surface of the housing 1a. Further, a sleeve 6 is fitted into the housing 1a, and forms a stator unit 15.

A shaft 9 is integrally formed with the fan 8,
Is rotatably fitted in the sleeve 6 in contact with the thruster 7. The fan 8 has a magnet 11 and a magnet yoke 1 facing the annular stator 3.
2 are fixed to form the rotor 16.

As shown in FIG. 2, a dynamic pressure generating groove 13 is formed on the inner peripheral surface of the sleeve 6 by ball rolling or the like. Further, the protrusion generated by the ball rolling is removed to reduce the inner diameter of the sleeve to ± 2 μm. Sizing is performed to finish with the following high precision.

As shown in FIG. 3, the dynamic pressure generating groove 13 is
The dynamic pressure generating groove 13 according to the present embodiment is formed at a portion where the shaft 9 and the sleeve 6 are opposed to each other.
Is formed so as not to penetrate the open end face of the gap, in other words, the end face on the fan 8 side.

In FIG. 2, a ventilation groove 20 extending from the opening of the housing 1a to the bottom surface is formed on the inner wall of the housing 1a or the outer periphery of the sleeve 6.

In the dynamic pressure generating groove 13, oil 1
4 is lubricated to form a radial bearing 17. Although the dynamic pressure generating groove 13 is formed on the inner peripheral surface of the sleeve 6 in the embodiment of the present invention, it may be formed on the outer peripheral surface of the shaft 9. Also at this time, the dynamic pressure generating groove 13 is formed so as not to protrude from the end face of the sleeve 6 on the fan 8 side.

The end face of the shaft 9 on the side opposite to the fan 8 is finished in a spherical shape, and comes into contact with the thruster 7 to form a thrust bearing 18.

According to the electric motor having such a configuration, the dynamic pressure generating groove 13 of the bearing does not penetrate the open end surface of the gap between the shaft 9 and the sleeve 6, so that the shaft 9 and the sleeve are not penetrated. The escape of air from the dynamic pressure generating groove portion in the larger gap between 6 and the outflow of oil due to the escape can be prevented.

By forming the ventilation groove 20 from the opening of the housing 1a to the bottom surface, the pressure of the oil in the bearing can be adjusted. It is possible to prevent oil from spouting from the gap between the bearings.

Next, the operation of the heat sink device of this embodiment will be described. When the motor rotates, the fan 8 also rotates, sucks air along the axis 9 of the motor, flows along the air flow path formed by the fins 21, and is exhausted from the opening provided in the side wall of the frame 1. You. At this time, the air flow takes heat from the frame 1 and the fins 21 to which the heat of the heating element is conducted, and performs a cooling action.
The direction of the opening on the side wall should be applied to electronic equipment using a heat sink so that the air exhausted from the heat sink can be applied to other heating elements and the hot air can be smoothly exhausted from the electronic equipment. In addition, it is used by opening in one direction or a plurality of directions.

The shape of the fin 21 is not limited to a plate shape or a pin shape, but may be any shape having the same function and effect as a triangular shape, a wing shape, a spiral shape, a circular shape, a radial shape, and the like.
When the size of the heat sink device is smaller than the predetermined size, the size of the motor is inevitably reduced, and as a result, the output of the motor is also reduced. Therefore, in the above case, the amount of air generated by the electric motor and the fan becomes small, and the heat radiation effect may be worsened. When the size of the heat sink device is smaller than the predetermined size as described above, it is desirable to improve the heat radiation effect by increasing the amount of air to be released without raising the fin.

[0040]

As described above, according to the present invention, the dynamic pressure generating groove for holding oil, which is formed on either the outer peripheral surface of the shaft or the inner peripheral surface of the sleeve, is provided between the shaft and the sleeve. By not penetrating to the open side of the gap, an effective effect of preventing the air and the accompanying oil from flowing out from the dynamic pressure generating groove in the gap between the shaft and the sleeve can be obtained.

Further, by forming a ventilation groove on the inner wall of the housing or on the outer periphery of the sleeve from the opening of the housing to the bottom surface, the pressure of oil in the bearing can be adjusted, and when the shaft is inserted into the bearing, An effective effect of preventing oil from being ejected from a gap between the bearing and the shaft can be obtained.

As a result, it is possible to prevent oil from flowing out of the bearing portion and oil shortage, and to obtain an effective effect that it is possible to obtain a motor having high reliability and long life.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a heat sink device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a bearing portion of the electric motor used in the heat sink device of FIG. 1;

FIG. 3 is a view showing a dynamic pressure generating groove in a bearing sleeve of the electric motor in FIG. 2;

FIG. 4 is a sectional view showing a heat sink device according to a conventional example.

FIG. 5 is a sectional view showing a bearing portion of the electric motor used in the heat sink device of FIG. 4;

FIG. 6 is a view showing a dynamic pressure generating groove in a bearing sleeve of the electric motor of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 frame 1a housing 2 coil 3 stator 4 drive circuit board 6 sleeve 7 thruster 8 fan 9 shaft 10 insulating sheet 11 magnet 12 magnet yoke 13 dynamic pressure generating groove 14 oil 15 stator unit 16 rotor 17 radial bearing 18 thrust bearing 20 ventilation groove 21 fin

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 7/14 H02K 7/14 A 21/22 21/22 MF Term (Reference) 3J011 AA07 BA04 BA08 CA01 CA02 JA02 5H605 AA04 BB05 BB19 CC05 DD07 EB01 5H607 AA04 BB01 BB09 BB14 BB17 CC01 DD03 GG01 GG12 GG15 5H621 GA04 HH01 JK01 JK11 JK13

Claims (6)

[Claims] 1. A frame provided with a cylindrical housing having an open end, a stator mounted on the frame, a sleeve fitted in the housing, and a shaft rotatably fitted in the sleeve. A rotor provided with a magnet opposed to the stator, oil filled in a gap between the shaft and the sleeve, and formed on one of an outer peripheral surface of the shaft or an inner peripheral surface of the sleeve. A dynamic pressure generating groove for holding the oil, wherein the dynamic pressure generating groove does not penetrate the opening end on the rotor side. 2. The electric motor according to claim 1, wherein a ventilation groove is formed in an inner wall of the housing or an outer periphery of the sleeve from an open end to a bottom of the housing. 3. An outer diameter of the shaft and an inner diameter of the sleeve are not more than 2 mm.
The electric motor according to claim 2. 4. A cooling fan motor provided with the electric motor according to claim 1, wherein a heating element can be attached to a frame of the electric motor. 5. The heat sink device according to claim 4, wherein plate-shaped or pin-shaped fins are erected on the frame. 6. The heat sink device according to claim 4, wherein one or more openings are provided in a side wall of the frame of the electric motor.