JPH0937516A - Cooling fan motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate high speed rotation and increase an air supply volume and facilitate low vibration rotation and protect apparatuses in a heating part. SOLUTION: A heatsink 1 composed of a heat conducting metal unit which is to be a base unit bonded to a heating part is provided. Fins 10 are stood on the outer circumference of the heatsink 1. A rotor 2 having a fan 16 is supported by the heatsink 1 with a shaft 3 and a bearing part so as to rotate freely and a stator 13 is provided on the outer circumference of the bearing part. The bearing part is composed of a dynamic pressure type fluid bearing having dynamic pressure producing trenches 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling fan motor which is used by being joined to a CPU section of electronic equipment.

[0002]

2. Description of the Related Art In recent years, for example, CPUs in electronic equipment
However, due to the increased speed, the amount of heat generated increases, and it is becoming difficult to satisfy the performance with natural cooling. Therefore,
A cooling fan motor is required to guarantee the operation of the CPU.

FIG. 4 is a sectional view showing the overall structure of a conventional cooling fan motor, the structure of which will be described below. As shown in the figure, this cooling fan motor is configured as an outer rotor, and a rolling bearing 102 is provided at the center of a heat sink 101 made of a heat-conducting metal body to be joined to a heat generating portion such as a CPU.
Is provided, and fins 103 are provided so as to project on the outer peripheral portion. A stator 104 is arranged around the rolling bearing 102.

The rotor 105 comprises a rotor hub 106, a magnet 107 mounted inside the outer peripheral wall of the rotor hub 106, and a fan 108 provided outside the outer peripheral wall of the rotor hub 106. The magnet 107 is located outside the stator 104. Correspondingly, it is rotatably supported by the rolling bearing 102 by the shaft 109. The heat sink 101 is attached to a member of the CPU by a heat conductive adhesive or a rubber band.

In the above structure, the heat generated by the operation of the CPU is transferred to the heat sink 101 and further to the fins 103. When the stator 104 is energized, a magnetic field is generated in the stator 104, which causes the rotor 105
Rotates. The rotation of the rotor 105 causes the fan 1
08 generates an air flow, and the CPU heatsink 10
The heat transferred to No. 1 was transferred to the air via the fin 103. As a result, the fin 103 has a function of radiating heat and cooling the CPU as a result, preventing the heating of the CPU and ensuring the normal operation of the CPU.

[0006]

However, the above-described conventional cooling fan motor has the following problems.

That is, downsizing is progressing in personal computers, especially notebook personal computers, and accordingly, in order to secure a mounting space for the cooling fan motor and a space necessary for the fan 108 to suck air, Although it is necessary to reduce the thickness of the cooling fan motor, the thickness of the rolling bearing 102 is mostly the thickness of the cooling fan motor, which makes it very difficult to reduce the thickness.

If the height of the fin 103 is reduced,
The surface area of the fins 103 that absorbs the heat generated by the CPU and transfers the heat to the air is reduced, and the heat dissipation efficiency is reduced. Further, if the height of the fan 107 is reduced, the amount of air blown is reduced, which also causes a reduction in heat dissipation efficiency.

It is conceivable to increase the number of rotations of the rotor 105 as a means for preventing such a decrease in heat radiation efficiency.
In the rolling bearing 102, when the number of rotations is increased, the vibration generated in the bearing portion is correspondingly increased, and the reliability of the rolling bearing 102 is deteriorated due to the disconnection between the CPU and the board on which the CPU is mounted.

The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a cooling fan motor capable of high-speed rotation, low vibration, and good heat dissipation efficiency.

[0011]

In order to achieve the above-mentioned object, the present invention has a heat sink made of a heat-conducting metal body which is a base to be joined to a heat generating portion, and fins are provided upright on the outer peripheral portion of the heat sink. A rotor having a fan is rotatably supported by a shaft and a bearing on a heat sink, a stator is arranged on the outer periphery of the bearing, and the bearing is a dynamic pressure type hydrodynamic bearing.

[0012]

In the above structure, since the hydrodynamic bearing produces pressure in the fluid due to the rotation of the rotor and maintains the non-contact state with the shaft, the rotor can be rotated at high speed and the amount of vibration is reduced, and the heat sink It is necessary for the CPU to operate normally by increasing the amount of air blown by the high speed rotation of the fan without causing any deterioration in reliability such as the soldering of the heat generating part joined to the board, for example, the CPU, to the soldering with the substrate. The amount of heat can be dissipated and the thickness of the cooling fan motor can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In the figure, 1 is a heat sink made of a heat-conducting metal body serving as a base to be joined to a heat generating portion such as a CPU, and a sleeve 4 for supporting a shaft 3 of a rotor 2 in a radial direction is fixed to the center portion thereof. Dynamic pressure generating grooves 5 are formed by ball rolling or the like at two positions above and below the inner peripheral surface of the sleeve 4, and oil 6 is injected as lubricating oil. The shaft 3 and the dynamic pressure generating groove 5 form a radial bearing 7 with a gap of several μm maintained. Although not shown, the lower end surface of the shaft 3 is formed into a spherical surface, and contacts the thruster 8 to form a thrust bearing 9.

Fins 1 are provided on the outer periphery of the heat sink 1.
0 is set up. A concave step portion 11 is formed on the inner side of the upper edge of the fin 10, and a fan retaining member 12 made of a heat-conducting metal material is adhered to the concave step portion 11 with a heat conductive adhesive to remove the fan. The stop member 12 is projected inward. A stator 13 is arranged on the outer circumference of the sleeve 4.

The rotor 2 is fixed to the rotor hub 14 supported by the shaft 3, and the magnet 1 fixed to the inside of the outer edge wall of the rotor hub 14 and corresponding to the stator 13.
5 and a fan 16 provided outside the outer edge wall so as to extend outward. And fan 16
A concave step portion 17 is formed on the outer side portion of the upper edge of the fan, and the concave step portion 17 is located below the fan retaining member 12.

In the above construction, the shaft 2 of the rotor 2 is rotatably supported by the radial bearing 7, and is held by the magnetic force between the magnet 15 and the stator 13. Then, when an external force larger than the rotor holding force due to the magnetic force between the magnet 15 and the stator 13 is applied, the shaft 16 of the rotor 2 does not come off from the sleeve 4 due to the contact between the fan 16 and the fan retaining member 12. .

When the cooling fan motor of this structure is mounted so that the heat sink 1 is in contact with, for example, the heat generating portion of the CPU, the heat generated by the operation of the CPU is transmitted to the heat sink 1, and the fins 10 and the fan are removed. It is transmitted to the stop member 12. When the stator 13 is energized, a magnetic field is generated in the stator 13, which causes the rotor 2 to rotate.

Here, the two dynamic pressure generating grooves 5 in the radial bearing 7 generate a pressure in the oil 6 by the pumping action, so that the shaft 3 rotates without contact with the sleeve 4. This rotation, that is, the rotation of the rotor 2, causes the fan 16 to generate an air flow, and transfers the heat transmitted from the CPU to the heat sink 1 to the air via the fins 10 and the fan retaining member 12. In this way, the heat can be dissipated by the fins 10 and the fan retaining member 12 to eventually cool the CPU.

Further, in order for the fan 16 to generate a sufficient air flow for cooling the CPU, a sufficient space is required around the fan 16, and therefore the thickness of the cooling fan motor is set to 7 mm or less. This space is secured.

As described above, since the cooling fan motor of this embodiment uses the hydrodynamic bearing as the rotor bearing, the rotor shaft and the sleeve rotate without contact, and the rotation thereof is prevented. The number of vibrations can be increased and the amount of vibration can be suppressed, the cooling efficiency of the CPU and the like can be improved, and the entire structure can be thinned. Further, since a concave step portion is provided on the inner side of the upper edge of the heat sink and a heat conductive fan retaining member is joined to the concave step portion, it is possible to expand the heat radiation area and provide a rotor retaining mechanism that is easy to assemble.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same components as those shown in FIG. 1 are designated by the same reference numerals, and the description of their assembling configuration and functions will be omitted.

The feature of this embodiment is that the concave step portion 11 of the fin 10 is used.
That is, the fan retaining member 18 joined to is formed in a ring shape.

With this configuration, an external force larger than the rotor holding force due to the magnetic force between the magnet 15 and the stator 13 is applied, and it is possible to more reliably prevent the rotor from coming off. Furthermore, since the fan retaining member 18 has a large area, it has a large function of transferring heat to the air.

As described above, in the cooling fan motor of this embodiment, the fan retaining member has a ring shape,
(EN) Provided is a rotor retaining mechanism which improves heat dissipation efficiency and is of course easy to assemble.

Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same components as those shown in FIG. 1 are designated by the same reference numerals, and the description of their assembling configuration and function will be omitted.

The feature of this embodiment lies in the rotor retaining structure. That is, the concave step portion 19 is formed on the upper inside of the fin 10, and the protruding piece 2 protruding outward is provided on the outer side of the fan 16.
In the state where 0 is formed and the projecting piece 20 is located in the concave step portion 19, a fan retaining member 21 protruding inward is bonded to the upper edge of the fin 10.

In the above structure, even if an external force larger than the rotor holding force due to the magnetic force between the magnet 15 and the stator 13 is applied, the projection 20 of the fan 16 contacts the fan retaining member 21 and the shaft 3 of the rotor 2 Will not come off from the sleeve 4.

The cooling fan motor of this embodiment also improves the heat radiation efficiency and provides a rotor retaining mechanism which is easy to assemble.

In each of the above embodiments, the dynamic pressure generating groove is formed on the inner peripheral portion of the sleeve, but the dynamic pressure generating groove may be formed on the outer periphery of the shaft. Although the sleeve is fixed and the shaft is rotated, the shaft may be fixed and the sleeve is rotated. Furthermore, although the cooling fan motor in each of the embodiments has been described for CPU cooling, it goes without saying that it can be used for cooling other heat generating portions of electronic equipment.

[0030]

As is apparent from the description of each of the above-described embodiments, since the bearing in the cooling fan motor is a hydrodynamic bearing in the present invention, low-vibration rotor rotation can be realized.
For example, when cooling the CPU,
There is no possibility that the reliability is deteriorated such that the soldering between the board and the board is disengaged. Also, since the number of rotations can be increased, the amount of air that can be radiated is required to operate the CPU normally even if the height of the fans and fins is lowered and the overall thickness is reduced. It is possible to increase the mounting space to the device, the air intake space, etc. by the above-mentioned thinning, which is advantageous as a cooling fan motor in the device. Further, since the rotor retaining mechanism is configured by associating the fan retaining member with the recessed portion of the fin, the cooling is easy to assemble and the cooling efficiency is improved by the heat radiation using the fan retaining member. Can provide a fan motor for use.

[Brief description of drawings]

FIG. 1 is a sectional view of a cooling fan motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a cooling fan motor according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a cooling fan motor according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing the entire structure of a conventional cooling fan motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 heat sink 2 rotor 3 shaft 4 sleeve 5 dynamic pressure generating groove 6 oil 7 radial bearing 8 thruster 9 thrust bearing 10 fin 11 concave step portion 12 fan retaining member 13 stator 14 rotor hub 15 magnet 16 fan 17 concave step portion

Claims (5)

[Claims] 1. A heat sink made of a heat-conducting metal body serving as a base body to be joined to a heat generating portion, fins provided upright on the outer periphery of the heat sink, a fan on the outer periphery of a rotor hub, and a rotor having a magnet inside thereof. A cooling unit characterized by comprising a shaft for rotatably supporting the rotor and a bearing unit, and a stator arranged on the outer periphery of the bearing unit and facing the magnet, wherein the bearing unit comprises a hydrodynamic bearing. Fan motor. 2. A hydrodynamic bearing comprises a sleeve, wherein a hydrodynamic groove is formed in either the inner circumference of the sleeve or the outer circumference of a shaft fitted in the sleeve, and oil is injected into the hydrodynamic groove. The cooling fan motor according to claim 1, configured as described above. 3. A concave step portion is formed on the inner side of the upper edge of the fin, and a concave step portion is also formed on the outer side of the upper edge of the fan, and a heat conductive fan retaining member is joined to the concave step portion of the fin. The cooling fan motor according to claim 1, wherein the fan retaining member is inwardly projected so as to be located above the concave step portion of the fan. 4. A recessed step portion is formed on an upper portion of an inner edge of the fin, and a projecting piece projecting outward is formed on an outer side of the fan. The projecting piece is positioned in the recessed step portion, and the upper edge of the fin is provided. The cooling fan motor according to claim 1, wherein a heat conductive fan retaining member having an inner end located above the protrusion is joined. 5. The cooling fan motor according to claim 3, wherein the fan retaining member is formed in a ring shape.