U.S. patent application number 12/168908 was filed with the patent office on 2009-09-17 for heat dissipation fan.
This patent application is currently assigned to FU ZHUN PRECISION INDUSTRY (SHEN ZHEN) CO., LTD.. Invention is credited to WEN-GAO WANG, ZHI-YA YANG.
Application Number | 20090232678 12/168908 |
Document ID | / |
Family ID | 41063240 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090232678 |
Kind Code |
A1 |
YANG; ZHI-YA ; et
al. |
September 17, 2009 |
HEAT DISSIPATION FAN
Abstract
An exemplary heat dissipation fan includes a fan housing 10, a
bearing assembly 20, a stator 30 and a rotor 40. The fan housing
includes a base 12 and a central tube 14 extending upwardly from
the base. The bearing assembly includes a bearing 23 received in
the central tube, a porous wick element 24 and a locking washer 25.
The stator is mounted around the central tube. The rotor includes a
shaft 47 extending through a bearing hole 231 of the bearing. The
locking washer is mounted around the shaft and fixed on a top end
of the central tube. The locking washer, the bearing and the shaft
cooperatively form an oil reservoir 50 in the top end of the
central tube. The porous wick element is received in the oil
reservoir and physically contacts with the bearing.
Inventors: |
YANG; ZHI-YA; (Shenzhen
City, CN) ; WANG; WEN-GAO; (Shenzhen City,
CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. Steven Reiss
458 E. LAMBERT ROAD
FULLERTON
CA
92835
US
|
Assignee: |
FU ZHUN PRECISION INDUSTRY (SHEN
ZHEN) CO., LTD.
Shenzhen City
CN
FOXCONN TECHNOLOGY CO., LTD.
Tu-Cheng
TW
|
Family ID: |
41063240 |
Appl. No.: |
12/168908 |
Filed: |
July 8, 2008 |
Current U.S.
Class: |
417/410.1 |
Current CPC
Class: |
F04D 29/0513 20130101;
F04D 25/0626 20130101; F04D 25/062 20130101; F04D 29/063 20130101;
F04D 29/051 20130101 |
Class at
Publication: |
417/410.1 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 14, 2008 |
CN |
200810065850.4 |
Claims
1. A heat dissipation fan comprising: a fan housing comprising a
base and a central tube extending upwardly from a top surface of
the base; a bearing assembly comprising a bearing, a porous wick
element and a locking washer, the bearing being received in the
central tube and defining a bearing hole therein; a stator mounted
around the central tube; and a rotor comprising a shaft extending
through the bearing hole of the bearing, the locking washer being
mounted around the shaft and fixed on a top end of the central
tube, wherein the locking washer, the bearing and the shaft
cooperatively define an oil reservoir in the top end of the central
tube, and the porous wick element is received in the oil reservoir
and physically contacts with the bearing.
2. The heat dissipation fan of claim 1, wherein the locking washer
comprises a retaining ring extending from the top end of the
central tube towards an outer surface of the shaft.
3. The heat dissipation fan of claim 2, wherein the locking washer
further comprises a cylindrical mounting portion, the retaining
ring extending inwardly from a top of the mounting portion towards
the shaft, an annular recess defined in a top portion of the
central tube for mounting the mounting portion of the locking
washer therein.
4. The heat dissipation fan of claim 3, wherein the locking washer
further comprises a cylindrical flange extending upwardly from a
top surface of the retaining ring, the flange and the mounting
portion being staggered to each other with a step formed on the top
surface of the retaining ring above the mounting portion, a top of
the central tube bended inwardly to form a pressing portion to
press on the step for keeping the locking washer and the bearing in
the central tube.
5. The heat dissipation fan of claim 4, wherein the rotor further
comprises a hub, the hub forming a shaft seat fixing one end of the
shaft and a cylindrical protrusion extending downwardly from the
hub around the shaft seat, a diameter of the flange being smaller
than a diameter of the protrusion, the flange extending from the
retaining ring into a chamber defined between the shaft seat and
the protrusion.
6. The heat dissipation fan of claim 2, wherein the shaft defines
an annular slot in a circumference thereof, at a position
corresponding to the locking washer, the retaining ring extending
from the central tube into the slot.
7. The heat dissipation fan of claim 1, wherein the porous wick
element is made of a porous material and defines a plurality of
pores therein.
8. The heat dissipation fan of claim 7, wherein the bearing defines
a circular cavity in a top portion thereof, the porous wick element
being received in the cavity, a bottom surface and an outer side
surface of the porous wick element being physically attached to a
top surface and a side surface of the bearing defining the circular
cavity, respectively.
9. The heat dissipation fan of claim 7, wherein the bearing is an
oil-impregnated sleeve bearing and defines a plurality of pores
therein.
10. The heat dissipation fan of claim 9, wherein the pores defined
in the porous wick element have an average pore size lager than
that of the pores defined in the bearing.
11. The heat dissipation fan of claim 1, wherein the bearing
assembly further comprises a magnetic unit, the magnetic unit
comprising a magnet, the base of the fan housing defining a
receiving concave on a bottom surface, the central tube defining a
central hole for receiving the bearing therein, the receiving
concave facing opposite to and being isolated from the central hole
of the central tube, the magnet being received in the receiving
concave.
12. The heat dissipation fan of claim 11, wherein the magnetic unit
further comprises a cup-shaped magnetic yoke enclosing the magnet
therein, and a top surface of the magnet is exposed out of the
magnetic yoke and faces toward a bottom of the shaft.
13. A heat dissipation fan comprising: a fan housing comprising a
base and a central tube extending upwardly from a center of the
base; a bearing received in the central tube and defining a bearing
hole therein; a stator mounted around the central tube; a rotor
comprising a shaft extending through the bearing hole of the
bearing, an oil reservoir being defined in the central tube near a
top end of the central tube; and a porous wick element received in
the oil reservoir and physically contacting with a top end of the
bearing.
14. The heat dissipation fan of claim 13, further comprising a
locking washer mounted to the top end of the central tube, the
locking washer including a retaining ring extending from the
central tube towards the shaft, the oil reservoir being defined
among the retaining ring, the bearing and the shaft.
15. The heat dissipation fan of claim 14, wherein the bearing
defines a cavity in a top end thereof, the porous wick element
being received in the cavity, a bottom surface and an outer side
surface of the porous wick element being physically attached to the
bearing.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to a heat dissipation fan, and
more particularly relates to a heat dissipation fan which has a
good lubricating effect.
[0003] 2. Description of Related Art
[0004] With the continuing development of the electronic
technology, electronic packages such as CPUs (central processing
units) are generating more and more heat that is required to be
dissipated immediately. Heat dissipation fans are commonly used in
combination with heat sinks for cooling CPUs. Performances of heat
dissipation fans mostly depend on performances of bearings used in
the heat dissipation fans. Good lubricating qualities of the
bearings increase the life-span of the bearings.
[0005] A typical heat dissipation fan comprises a fan housing
having a central tube extending upwardly therefrom, a bearing
received in the central tube, a stator mounted around the central
tube, and a rotor rotatable with respect to the stator. The rotor
includes a hub and a shaft extending from the hub into the bearing.
The central tube has an opening defined at a top end thereof. The
bearing is inserted into the central tube through the opening.
Lubricating oil is injected into the central tube to lubricate the
bearing and the shaft. A lubricating effect of the bearing and the
shaft can be properly maintained when the heat dissipation fan is
vertically mounted. However, when the heat dissipation fan is
mounted in an upside-down manner, the lubricating oil will leak out
of the central tube through the opening of the central tube and the
amount of the lubricating oil in the bearing is thus gradually
reduced. The friction between the shaft and the bearing is
therefore increased due to a decrease of the lubricating oil, which
results in uncomfortable noise or malfunction being generated. As a
result, the performance of the heat dissipation fan deteriorates,
and the life-span of the fan is accordingly shortened.
[0006] What is needed, therefore, is a heat dissipation fan which
can reduce or eliminate a leakage of the lubricant oil from the
bearing thereof.
SUMMARY
[0007] The present invention relates to a heat dissipation fan.
According to an embodiment of the present invention, the heat
dissipation fan includes a fan housing, a bearing assembly, a
stator and a rotor. The fan housing includes a base and a central
tube extending upwardly from a top surface of the base. The bearing
assembly includes a bearing received in the central tube and
defining a bearing hole therein, a porous wick element and a
locking washer. The stator is mounted around the central tube. The
rotor includes a shaft extending through the bearing hole of the
bearing. The locking washer is mounted around the shaft and fixed
on a top end of the central tube. The locking washer, the bearing
and the shaft cooperatively form an oil reservoir in the top end of
the central tube. The porous wick element is received in the oil
reservoir and physically contacts with the bearing.
[0008] Other advantages and novel features of the present invention
will become more apparent from the following detailed description
of preferred embodiment when taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 an assembled, isometric view showing a heat
dissipation fan in accordance with an embodiment of the present
invention.
[0010] FIG. 2 is an exploded, isometric view of the heat
dissipation fan of FIG. 1.
[0011] FIG. 3 is a view similar to FIG. 2, but shown in an
up-side-down aspect.
[0012] FIG. 4 is a cross-section view of the heat dissipation fan
of FIG. 1, taken along line IV-IV thereof.
[0013] FIG. 5 is an enlarged view of a circled portion V of FIG.
4.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0014] Reference will now be made to the drawings to describe the
various present embodiments in detail.
[0015] Referring to FIGS. 1-3, a heat dissipation fan according to
an embodiment includes a rotor 40, a stator 30 in respect to which
the rotor 40 is rotatable, a fan housing 10 receiving the rotor 40
and the stator 30 therein, and a bearing assembly 20.
[0016] The fan housing 10 comprises a base 12 and a central tube 14
extending upwardly from a top surface of a central portion of the
base 12. The central tube 14 defines a central hole 142 therein and
forms an open end at a top portion thereof. An annular recess 144
is formed on an inner circumference of the top portion of the
central tube 14. The annular recess 144 communicates with the
central hole 142. The top portion of the central tube 14 has an
inner diameter which is larger than that of the other portion of
the central tube 14. A receiving concave 120 is formed on a bottom
surface of the central portion of the base 12. The receiving
concave 120 faces opposite to the central hole 142 of the central
tube 14 and is isolated from the central hole 142 of the central
tube 14 by the base 12. In other words, the receiving concave 120
is aligned with the central hole 142, but does not communicate with
the central hole 142.
[0017] The stator 30 comprises a stator core 33 consisting of
several layers of yokes, stator coils 35 wound around the stator
core 33 to establish an alternating magnetic field, and a PCB
(printed circuit board) 31 electrically connected with the stator
coils 35. To avoid the coils 35 from electrically contacting with
the stator core 33, upper and lower insulating frames 37 are used
to cover the stator core 33 and electrically insulate the stator
coils 35 from the stator core 33.
[0018] The rotor 40 comprises a hub 42 forming downwardly a shaft
seat 46 at a central portion thereof, a plurality of fan blades 44
extending radially outwardly from an outer periphery of the hub 42,
an annular magnet 45 adhered to an inner surface of the hub 42, and
a shaft 47 retained in and extending downwardly from the shaft seat
46. The shaft 47 defines an annular slot 471 in a circular
circumference thereof, at a position near a top end of the shaft 47
which locates adjacent to the hub 42. A cylindrical protrusion 48
extends downwardly from the hub 42, wherein the protrusion 48
surrounds and spaces a distance from the shaft seat 46. The
protrusion 48 and the shaft seat 46 cooperatively define an annular
chamber 480 therebetween.
[0019] The bearing assembly 20 comprises a wear pad 21, a bearing
23, a porous wick element 24, a locking washer 25 and a magnetic
unit 27. The bearing 23 is a sleeve bearing and made from sintering
powders such as copper powders or ceramic powders. A plurality of
pores (not shown) are defined in the bearing 23 and communicate
with each other. The bearing 23 is received in the central hole 142
of the central tube 14 via the open end of the central tube 14. The
bearing 23 defines an axial hole 231 therein for extension of the
shaft 47 therethrough. A circular cavity 232 is formed in a top
portion of the bearing 23. The cavity 232 communicates with the
axial hole 231. Thus, the top portion of the bearing 23 has an
inner diameter which is larger than that of the other portion of
the bearing 23. Two channels 234 are axially defined in an outer
surface of the bearing 23. The channels 234 communicate with the
axial hole 231 of the bearing 23 for guiding oil at the top portion
of the bearing 23 to return back to a bottom portion of the bearing
23.
[0020] The porous wick element 24 is cylindrically-shaped in
configuration. The porous wick element 24 is made of a porous
material, such as polyurethane foam plastic, foamed metal or
sponge. The porous wick element 24 is received in the cavity 232 of
the bearing 23. More specifically, a bottom surface and an outer
circumference surface of the porous wick element 24 are
interferentially and physically respectively attached to a top
surface and a side surface of the bearing 23 defining the cavity
232. A plurality of pores (not shown) are defined in the porous
wick element 24 and communicate with each other.
[0021] The locking washer 25 is made of a material having high
strength, high abrasion resistance and low friction factor, such as
nylon. Referring to FIGS. 4-5, the locking washer 25 comprises a
cylindrical mounting portion 251, a retaining ring 253 extending
inwardly from a top end of the mounting portion 251, and a flange
255 extending upwardly and perpendicularly from a top surface of
the retaining ring 253. The flange 255 offsets inwardly a distance
with respect to the mounting portion 251. An inner diameter of the
flange 255 is greater than an inner diameter of the retaining ring
253.
[0022] The mounting portion 251 has an outer diameter substantially
equals to the diameter of the annular recess 144 of the central
tube 14. The retaining ring 253 extends horizontally from the top
end of the mounting portion 251 towards the slot 471 of the shaft
47, and substantially covers the open end of the central tube 14.
The retaining ring 253 defines an inner hole 250 in a middle
portion for extension of the shaft 47 therethrough. A diameter of
the inner hole 250 of the retaining ring 253 is slightly larger
than a diameter of an outer surface of the shaft 47 at the slot
471, but smaller than a diameter of the other portion of the shaft
47. Thus, the retaining ring 253 of the locking washer 25 is
engaged in the slot 471 of the shaft 47 to limit an axial movement
of the shaft 47. A narrow gap is defined between an inner
circumferential surface of the retaining ring 253 and the outer
surface of the shaft 47 defining the slot 471, in order to avoid an
interference between the shaft 47 and the retaining ring 253 during
rotation of the shaft 47. The flange 255 and the mounting portion
251 are staggered to each other, thereby forming a step 254 on the
top surface of the retaining ring 253 above the mounting portion
251. In other words, the step 254 is formed between the mounting
portion 251 and the flange 255. A diameter of the flange 255 is
smaller than a diameter of the protrusion 48 of the hub 42. The
flange 255 extends upwardly from the top surface of the retaining
ring 253 into the annular chamber 480.
[0023] The wear pad 21 is made of high abrasion resistant material.
The wear pad 21 is mounted in a bottom end of the central hole 142
of the central tube 14, for supporting a bottom end of the shaft
47.
[0024] The magnetic unit 27 comprises a magnetic yoke 273 and a
columned magnet 271. The magnetic yoke 273 is cup-shaped, having a
close end and an opposite open end. An axial cross-sectional view
of the magnetic yoke 273 is "U" shaped. The magnetic yoke 273
encloses the magnet 271 therein, along with a top surface of the
magnet 271 exposed out of the magnetic yoke 273. Bottom surface and
side surface of the magnet 271 are affixed to an inner surface of
the magnetic yoke 273 to connect the magnet 271 and the magnetic
yoke 273 together.
[0025] When assembled, the bearing 23 is mounted into the central
tube 14, and the shaft 47 is rotatably received in the bearing 23.
The porous wick element 24 is received in the cavity 232 of the
bearing 23. The mounting portion 251 is pressingly fitted in the
annular recess 144 of the central tube 14. The top portion of the
central tube 14 is bent inwardly to form a pressing portion 145
abutting on the step 254 of the retaining ring 253 for keeping the
locking washer 25 and the bearing 23 in the central tube 14. The
retaining ring 253 of the locking washer 25, the bearing 23 and the
shaft 47 cooperatively form an oil reservoir 50 at the top portion
of the bearing 23. The porous wick element 24 is received in the
oil reservoir 50. The magnet 271 and the magnetic yoke 273 are both
received in the receiving concave 120 of the base 12 of the fan
housing 10, wherein the top surface of the magnet 271 faces to the
bottom end of the shaft 47.
[0026] During operation, the rotor 40 is driven to rotate by the
interaction between the alternating magnetic field established by
the coils 35 of the stator 30 and the magnet 45 of the rotor 40.
The lubricating oil creeps up along the rotating shaft 47 under the
influence of the centrifugal force generated by the rotation of the
shaft 47 and then escapes to the oil reservoir 50 through a
clearance defined between the top end of the bearing 23 and the
shaft 47. The slot 471 of the shaft 47 prevents the oil from
continuously creeping up along the shaft 47. Since the oil
reservoir 50 is almost hermetically sealed by the retaining ring
253, the retaining ring 253 can prevent the lubricating oil from
leaking out of the oil receiver 50.
[0027] As the porous wick element 24 defines a plurality of pores
therein, the porous wick element 24 can absorb the lubricating oil
accumulated in the oil receiver 50, thereby further preventing the
lubricating oil from leaking out of the oil receiver 50. The porous
wick element 24 then returns the lubricating oil back to the
bearing 23 under a capillary force generated by the pores of the
bearing 23. The porous wick element 24 can absorb the lubricating
oil in the oil reservoir 50 and prevent the lubricating oil from
leaking out of oil reservoir 50 whether the heat dissipation fan is
positioned in a top side up manner, a lain down manner, or an
upside-down manner according to requirements. Preferably, the pores
defined in the porous wick element 24 have an average pore size
lager than that of the pores defined in the bearing 23, which makes
the bearing 23 generate a larger capillary force than the porous
wick element 24 to accelerate the lubricating oil flowing back to
the bearing 23 from the porous wick element 24. Thus, the
lubricating oil is kept from leaking out of the bearing 23. Good
lubrication of the bearing 23 and the shaft 47 is thus consistently
maintained, thereby improving the quality and life-span of the heat
dissipation fan.
[0028] Moreover, the flange 255 of the locking washer 25 can
further prevent the lubricating oil from leaking out of the oil
reservoir 50. The bottom surface and the side surface of the magnet
271 are covered by the magnetic yoke 273, which prevents magnetic
energy from leaking out from the magnetic yoke 273. Thus, the
magnet 271 can generate a magnetic attraction force which attracts
the shaft 47 to always maintain in contact with the wear pad 21 and
prevents the shaft 47 from floating along an axial direction of the
bearing 23. The axially upward movement of possible floating of the
rotor 40 during operation of the heat dissipation fan is avoided,
whereby the rotor 40 is maintained to rotate steadily.
[0029] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the embodiments, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *