U.S. patent application number 11/769663 was filed with the patent office on 2008-11-27 for cooling fan.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to YING-MIN HUANG, YEU-LIH LIN, ZHI-JIAN PENG, ZHI-YA YANG.
Application Number | 20080292479 11/769663 |
Document ID | / |
Family ID | 40072577 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080292479 |
Kind Code |
A1 |
LIN; YEU-LIH ; et
al. |
November 27, 2008 |
COOLING FAN
Abstract
A cooling fan includes a fan housing (10) having an upper tube
(111) extending downwardly from a top side thereof and a lower tube
(121) extending upwardly from a bottom side thereof, a ball bearing
(20) being mounted in the upper tube, a sleeve bearing (30) being
mounted in the lower tube, a stator (45) mounted around the lower
tube, and a rotor (40). The rotor includes a hub (401) located
between the ball bearing and the sleeve bearing and a shaft (50)
extending through the hub. Two ends of the shaft are rotatably
received in the ball bearing and the sleeve bearing,
respectively.
Inventors: |
LIN; YEU-LIH; (Tu-Cheng,
TW) ; HUANG; YING-MIN; (Tu-Cheng, TW) ; YANG;
ZHI-YA; (Shenzhen, CN) ; PENG; ZHI-JIAN;
(Shenzhen, CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. CHENG-JU CHIANG
458 E. LAMBERT ROAD
FULLERTON
CA
92835
US
|
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
Tu-Cheng
TW
|
Family ID: |
40072577 |
Appl. No.: |
11/769663 |
Filed: |
June 27, 2007 |
Current U.S.
Class: |
417/423.7 ;
415/229; 417/423.13 |
Current CPC
Class: |
F04D 29/056 20130101;
F04D 25/062 20130101; F04D 25/0626 20130101 |
Class at
Publication: |
417/423.7 ;
415/229; 417/423.13 |
International
Class: |
F04D 29/05 20060101
F04D029/05 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2007 |
CN |
200710074601.7 |
Claims
1. A cooling fan comprising: a fan housing having an upper tube
extending downwardly from a top side thereof and a lower tube
extending upwardly from a bottom side thereof; a ball bearing and a
sleeve bearing being mounted in the upper and lower tubes,
respectively; a stator mounted around the lower tube; and a rotor
comprising a hub located between the ball bearing and the sleeve
bearing and a shaft extending through the hub, top and bottom ends
of the shaft being rotatably received in the ball bearing and the
sleeve bearing, respectively.
2. The cooling fan of claim 1, wherein the housing comprises a
lower portion and an upper portion facing towards each other, the
lower and upper tubes being respectively formed on the lower and
upper portions of the housing.
3. The cooling fan of claim 2, wherein the top end of the shaft
extends through the upper portion of the housing and defines a slot
thereon, a locking ring being arranged on the upper portion of the
housing and engaging into the slot of the shaft to limit movement
of the shaft along an axial direction thereof.
4. The cooling fan of claim 1, wherein a wear pad made of highly
abrasion-resistant material is arranged in a bottom end of the
lower tube to face and supportively engage the bottom end of the
shaft.
5. The cooling fan of claim 1, wherein a spring is arranged between
the ball bearing and the hub.
6. The cooling fan of claim 5, wherein the spring is
conical-shaped, one end of the spring with a relatively small
diameter abutting against an inner ring of the ball bearing, and an
opposite end of the spring with a relatively large diameter
abutting against the hub.
7. The cooling fan of claim 1, wherein the lower tube defines an
end opening in a top end receiving an oil retaining ring therein,
and an oil buffer is defined among the shaft, the sleeve bearing,
the lower tube and the oil retaining ring.
8. The cooling fan of claim 7, wherein the shaft defines a notch in
an outer surface thereof, the notch being located in the oil
buffer.
9. The cooling fan of claim 7, wherein a plurality of grooves are
defined in an outer surface of the sleeve bearing and communicate
with the oil buffer.
10. A cooling fan comprising: a hub having a plurality of fan
blades extending radially and outwardly from an outer periphery
thereof, and a shaft extending through a central portion of the
hub; a ball bearing being arranged above the hub; and a sleeve
bearing being arranged under the hub; wherein the ball bearing and
the sleeve bearing are respectively mounted around top and bottom
ends of the shaft for supporting rotation of the shaft.
11. The cooling fan of claim 10, wherein a spring is arranged
between the hub and the ball bearing, and abuts against the ball
bearing and the hub.
12. The cooling fan of claim 11, wherein the spring is
conical-shaped, one end of the spring with a relatively smaller
diameter abutting against an inner ring of the ball bearing, and an
opposite end of the spring with a relatively larger diameter
abutting against the hub.
13. The cooling fan of claim 10, wherein the shaft defines a slot
at each of the top and bottom ends for receiving a locking
ring.
14. The cooling fan of claim 13, wherein the ball bearing and the
sleeve bearing are respectively received in upper and lower tubes,
the top end of the shaft extending through the upper tube and the
bottom end of the shaft being received in the lower tube, a wear
pad being arranged in the lower tube to face and supportively
engage the bottom end of the shaft.
15. The cooling fan of claim 14, wherein the lower tube defines an
end opening in a top end receiving an oil retaining ring therein,
an oil buffer being defined among the shaft, the sleeve bearing,
the lower tube and the oil retaining ring, the shaft defining a
notch in an outer surface thereof and located in the oil buffer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cooling fan, and more
particularly relates to a cooling fan having an improved bearing
assembly.
[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 requires immediate
dissipation. Cooling fans are commonly used in combination with
heat sinks for cooling CPUs.
[0005] Oftentimes, a cooling fan includes a blade set and a fan
seat. The fan seat has a central tube portion integrally formed
thereon. A pair of sleeve bearings are arranged in the tube
portion. A coil is wound around the outside of the tube portion.
The blade set is formed with a cap and fan blades connecting to the
cap. A stainless steel rotary shaft supported by the pair of sleeve
bearings at two opposite ends thereof is arranged within the cap. A
magnet pushed by magnetic force of the coil is fixed to the cap and
is driven to rotate by the coil so that the fan blades can produce
an airflow. Since the aforesaid stainless steel rotary shaft is
arranged on the sleeve bearings to rotate, after rotating for a
period of time, the rotary shaft and the bearings will experience
wear due to leaking of lubricating oil contained therebetween.
Thus, the lifetime of the fan will be reduced. In order to improve
the lifetime of the fan, wear-tolerable ball bearings for point
contact have been developed. However, the manufacturing process for
ball bearings requires precision-grinding and a high polish, and
thus the ball bearings are more expensive, which results in higher
expense.
[0006] For the foregoing reasons, therefore, there is a need in the
art for a cooling fan which overcomes the above-mentioned
problems.
SUMMARY OF THE INVENTION
[0007] According to a preferred embodiment of the present
invention, a cooling fan includes a fan housing having an upper
tube extending downwardly from a top side thereof and a lower tube
extending upwardly from a bottom side thereof, a ball bearing being
mounted in the upper tube, a sleeve bearing being mounted in the
lower tube, a stator mounted around the lower tube, and a rotor.
The rotor includes a hub located between the ball bearing and the
sleeve bearing, and a shaft extending through the hub. Two ends of
the shaft are rotatably received in the ball bearing and the sleeve
bearing, respectively.
[0008] Other advantages and novel features of the present invention
will be drawn from the following detailed description of the
preferred embodiments of the present invention with attached
drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Many aspects of the present cooling fan can be better
understood with reference to the following drawings. The components
in the drawings are not necessarily drawn to scale, the emphasis
instead being placed upon clearly illustrating the principles of
the present cooling fan. Moreover, in the drawings, like reference
numerals designate corresponding parts throughout the several
views.
[0010] FIG. 1 is an isometric, exploded view of a cooling fan in
accordance with a preferred embodiment of the present
invention;
[0011] FIG. 2 is an exploded view of the cooling fan of FIG. 1
viewed from another aspect;
[0012] FIG. 3 is an assembled view of the cooling fan of FIG. 1;
and
[0013] FIG. 4 is a cross sectional view of the cooling fan taken
from line IV-IV of FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring to FIGS. 1 through 4, a cooling fan according to a
preferred embodiment includes a fan housing 10, a ball bearing 20
and a sleeve bearing 30, a rotor 40, and a stator 45 in respective
to which the rotor 40 is rotatable.
[0015] The fan housing 10 includes a lower portion 12 and an upper
portion 11 mounted on the lower portion 12. Each portion 11, 12 of
the housing 10 includes a base 119, 129 and a tube 111, 121
extending perpendicularly from a central portion of the base 119,
129. The upper tube 111 extends downwardly from the base 119 of the
upper portion 111 of the housing 10. An upper central hole 112
extends through the upper tube 111 for receiving the ball bearing
20 therein. The lower tube 121 extends upwardly from the base 129
of the lower portion 12 of the housing 10. The lower tube 121 has a
top end being open and a bottom end being closed. A lower central
hole 122 is defined in the lower tube 121 for receiving the sleeve
bearing 30 therein. An annular recess 125 communicating with the
lower central hole 122 is formed on an inner circumference of the
top end of the lower tube 121 with a diameter larger than that of
the lower central hole 122. Thus the top end of the lower tube 121
has an inner diameter larger than that of the other portion of the
lower tube 121. An annular protrusion extends inwardly from the
inner circumference of the bottom end of the lower tube 121, and
thus forms a step 124 in the lower central hole 122 at the bottom
end of the lower tube 121.
[0016] The stator 45 includes a stator core 451 with coils wound
thereon to establish an alternating magnetic field, and a PCB 452
(printed circuit board) with electronic components mounted thereon
being electrically connected with the coils to control electrical
current flowing through the coils. The rotor 40 includes a hub 401
forming a shaft seat at a central portion thereof, a plurality of
fan blades 402 extending radially and outwardly from an outer
periphery of the hub 401, a magnet 41 adhered to an inner side of
the hub 401 and confronting the coils of the stator 45, and a shaft
50 extending through the shaft seat of the rotor 40. Two ends
(i.e., top and bottom ends) of the shaft 50 respectively extend to
upper and lower sides of the hub 401. An annular slot 501, 502 is
respectively defined on the shaft 50 near the top and bottom ends
thereof. An annular notch 503 is defined in a circular
circumference of a middle of the shaft 50, under the hub 401.
[0017] The ball bearing 20 is arranged in the upper tube 111. As a
conventional ball bearing, the ball bearing 20 includes an annular
inner ring 21, an annular outer ring 23 and a plurality of balls 22
sandwiched between the inner and outer rings 21, 23. An outer
diameter of the outer ring 23 is substantially the same as a
diameter of the upper central hole 112 of the upper tube 111, and
an inner diameter of the inner ring 21 is approximately the same as
the diameter of the shaft 50. The sleeve bearing 30 is arranged in
the lower tube 121. A bearing hole 31 is defined in the sleeve
bearing 30. A plurality of grooves 32 are defined in an outer
surface of the sleeve bearing 30. The grooves 32 communicate with
the bearing hole 31.
[0018] During assembly, the upper and lower portions 11, 12 of the
housing 10 are stacked together and face towards each other. A
space is defined in the housing 10 between the two portions 11, 12.
The stator 45 is received in the space and mounted around the lower
tube 121 of the lower portion 12 of the housing 10. The ball
bearing 20 and the sleeve bearing 30 are respectively mounted into
the central holes 112, 122 of the upper and lower tubes 111, 121.
The rotor 40 is arranged between the two tubes 111, 121 with the
hub 401 mounted around the stator 45. The top end of the shaft 50
of the rotor 40 extends through the ball bearing 20 and the upper
tube 111. An upper locking ring 81 is arranged on the upper tube
111 and engaged into the slot 501 of the top end of the shaft 50 to
limit movement of the shaft 50 along an axial direction thereof.
The bottom end of the shaft 50 extends through the sleeve bearing
30 into the bottom end of the lower tube 121. A wear pad 90 made of
highly abrasion-resistant material is arranged in the bottom end of
the lower tube 121 facing and supportively engaging with the bottom
end of the shaft 50. A lower locking ring 80 is arranged on the
step 124 of the lower tube 121 and located between the bottom end
of the sleeve bearing 30 and the protrusion of the lower tube 121.
The lower locking ring 80 engages into the slot 502 of the bottom
end of the shaft 50 thus limiting movement of the shaft 50 along
the axial direction thereof.
[0019] The ball bearing 20 has a height approximately the same as
or a little smaller than that of the upper tube 111. A
conical-shaped coil spring 60 is arranged between the ball bearing
20 and the hub 401 for providing the ball bearing 20 and the hub
401 with a preset engaging pressure therebetween, thus ensuring
that the ball bearing 20 remains stationary relative to the hub 401
in the axial direction of the shaft 50. A top end of the spring 60
abutting against the inner ring 21 of the ball bearing 20 has a
diameter relatively smaller than that of a bottom end of the spring
60 abutting against the hub 401. The sleeve bearing 30 has a height
lower than that of the lower tube 121. The sleeve bearing 30
consists of porous material made of sintered metal or the like, and
is impregnated with lubricating oil. A bearing clearance defined
between the sleeve bearing 30 and the shaft 50 is also filled with
lubricating oil. An oil retaining ring 70 is arranged in the recess
125 of the top end of the lower tube 121 and located above the
notch 503 of the shaft 50 for preventing leakage of the lubricating
oil from the sleeve bearing 30. An oil buffer 100 is thus defined
among the oil retaining ring 70, the sleeve bearing 30, the lower
tube 121 and the shaft 50 for receiving the lubricating oil
provisionally. The oil buffer 100 communicates with the bearing
hole 31 and the grooves 32 of the sleeve bearing 30; thus, the
lubricating oil received in the oil buffer 100 can flow back to the
sleeve bearing 30 through the grooves 32.
[0020] During operation, the rotor 40 is driven to rotate by the
interaction of the alternating magnetic field established by the
stator 45 and the magnetic field of the magnet 41 of the rotor 40.
Due to the support of the ball bearing 20 and the sleeve bearing 30
arranged on the top and bottom ends of the shaft 50, rotation of
the shaft 50 is smooth and stable. The two bearings 20, 30 are
respectively fixed in place and thus are spaced from each other;
the lubricating oil of the sleeve bearing 30 cannot flow into the
ball bearing 20 and thus interference between the two bearings 20,
30 is avoided. Use of the ball bearing 20 thus gives a longer
operational lifespan to the cooling fan. The sleeve bearing 30 can
reduce the cost of the cooling fan as it is cheaper. Thus the
bearing assembly of one ball bearing 20 and one sleeve bearing 30
can achieve a relatively low cost and a relatively high performance
at the same time, thus improving the life-span of the cooling fan
and reducing the cost of the cooling fan.
[0021] It is understood that the invention may be embodied in other
forms without departing from the spirit thereof. Thus, the present
example and embodiment are to be considered in all respects as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein.
* * * * *