U.S. patent application number 11/295506 was filed with the patent office on 2007-02-08 for passive fan assembly.
This patent application is currently assigned to DELTA ELECTRONICS, INC.. Invention is credited to Shun-Chen Chang, Chia-Ming Hsu, Wen-Shi Huang.
Application Number | 20070031248 11/295506 |
Document ID | / |
Family ID | 37670118 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070031248 |
Kind Code |
A1 |
Hsu; Chia-Ming ; et
al. |
February 8, 2007 |
Passive fan assembly
Abstract
A passive fan assembly includes an impeller and a plurality of
guide blades disposed in front of the impeller. The impeller
includes a plurality of blades extending at about 90 degrees
relative to the guide blades. Thus, when airflow enters the passive
fan assembly, the guide blades guide the airflow to effectively
impact on blades of the impeller.
Inventors: |
Hsu; Chia-Ming; (Taoyuan
Hsien, TW) ; Chang; Shun-Chen; (Taoyuan Hsien,
TW) ; Huang; Wen-Shi; (Taoyuan Hsien, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
DELTA ELECTRONICS, INC.
|
Family ID: |
37670118 |
Appl. No.: |
11/295506 |
Filed: |
December 7, 2005 |
Current U.S.
Class: |
415/191 |
Current CPC
Class: |
F04D 29/544 20130101;
F04D 25/08 20130101 |
Class at
Publication: |
415/191 |
International
Class: |
F01D 9/00 20060101
F01D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 2005 |
TW |
94126512 |
Claims
1. A passive fan assembly comprising: a base; an impeller mounted
on the base and comprising a hub and a plurality of blades disposed
around the hub; and a cover placed over the base and comprising a
plurality of guide blades corresponding to the plurality of blades
of the impeller.
2. The passive fan assembly as claimed in claim 1, wherein each
guide blade extends at an angle relative to the corresponding blade
of the impeller.
3. The passive fan assembly as claimed in claim 2, wherein the
angle is approximately 90 degrees.
4. The passive fan assembly as claimed in claim 1, wherein the
impeller further comprises a plurality of active blades disposed
around the plurality of blades.
5. The passive fan assembly as claimed in claim 4, wherein the
impeller further comprises a partition disposed between the
plurality of blades and the active blades.
6. The passive fan assembly as claimed in claim 1, wherein the base
comprises a frame, a bearing seat for receiving at least one
bearing therein, and a plurality of connecting elements connecting
the frame and the bearing seat, and the impeller includes a rotary
shaft extending into the bearing seat.
7. The passive fan assembly as claimed in claim 1, wherein the
cover further comprises a frame connected to the base, a stationary
part around which the plurality of guide blades are disposed, a
stationary ring connected to ends of the plurality of guide blades,
and a plurality of supporting elements connecting the stationary
ring and the frame.
8. The passive fan assembly as claimed in claim 1, wherein the
plurality of guide blades have inclined surfaces.
9. The passive fan assembly as claimed in claim 1, wherein the
passive fan assembly is driven by an airflow generated by an
airflow-providing system, and the airflow passes through the
plurality of guide blades into the passive fan assembly.
10. The passive fan assembly as claimed in claim 9, wherein the
airflow-providing system comprises an axial fan or an air
blower.
11. The passive fan assembly as claimed in claim 9, wherein the
airflow-providing system comprises an airflow outlet connected to
the cover of the passive fan assembly.
12. A passive fan assembly comprising: a housing comprising a
plurality of guide blades on a side thereof; an impeller installed
in the housing, comprising a hub, a plurality of blades encircling
the hub, a partition connected to ends of the plurality of blades,
and a plurality of active blades encircling the partition.
13. The passive fan assembly as claimed in claim 12, wherein the
plurality of guide blades corresponds to the plurality of blades of
the impeller.
14. The passive fan assembly as claimed in claim 13, wherein each
guide blade extends at an angle relative to the corresponding
runner blade of the impeller.
15. The passive fan assembly as claimed in claim 14, wherein the
angle is approximately 90 degrees.
16. The passive fan assembly as claimed in claim 12, wherein the
housing further comprises a stationary part around which the
plurality of guide blades are disposed, a stationary ring connected
to ends of the plurality of guide blades, and a plurality of
supporting elements connecting the stationary ring and the
housing.
17. The passive fan assembly as claimed in claim 12, wherein the
plurality of guide blades have inclined surfaces.
18. The passive fan assembly as claimed in claim 12, wherein the
passive fan assembly is rotated by airflow generated from an
airflow-providing system and the airflow passes through the
plurality of guide blades into the passive fan assembly.
19. The passive fan assembly as claimed in claim 18, wherein the
airflow-providing system comprises an axial fan or air blower.
20. The device as claimed in claim 18, wherein the
airflow-providing system comprises an airflow outlet connected to
the side of the housing.
Description
BACKGROUND
[0001] The invention relates to a passive fan assembly, and in
particular, to a passive fan assembly provided with guide blades
for increasing the kinetic energy received by the impeller of the
assembly in operation and promoting the efficiency of energy
transfer.
[0002] Generally, a fan is used together with a motor. The motor
rotates the fan to dissipate heat.
[0003] A conventional fan presents the following drawbacks. A fan
and a motor are generally used together, thus, a consumer must pay
for the motor and the fan. The motor, coupled to a fan, occupies
additional space even if the size of the motor is minimized.
Moreover, if the components to be cooled are disposed in different
locations in an electronic system, more than one fan and motor are
required. More motors used in the electronic system indicate more
power has to be provided and consumed, which does not conform to
the trend of saving power.
[0004] Thus, a passive fan assembly capable of providing an
improved heat-dissipating efficiency by effectively using airflow
is desirable.
SUMMARY
[0005] The invention provides a passive fan assembly comprising a
plurality of guide blades disposed in front of an impeller. The
guide blades extend at about 90 degrees relative to blades of the
impeller. Thus, in operation, the airflow passes through the guide
blades, turns, and impacts on the blades of the impeller at about
90 degrees, thereby effectively rotating the impeller and promoting
the heat-dissipating efficiency.
[0006] A passive fan assembly in accordance with an exemplary
embodiment of the invention includes a base, an impeller connected
to the base, and a cover disposed in front of the impeller and
connected to the base.
[0007] The impeller includes a hub, a plurality of runner blades
disposed around the hub, a partition connected to ends of the
runner blades, a plurality of active blades disposed around the
partition, and a rotary shaft axially extending from the hub.
[0008] The base includes a frame, a bearing seat, a plurality of
connecting elements connecting the frame and the bearing seat, and
a bearing disposed in the bearing seat for holding the rotary shaft
of the impeller.
[0009] The cover includes a frame, a stationary part, a plurality
of guide blades disposed around the stationary part, a stationary
ring connected to ends of the guide blades, and a plurality of
supporting elements connecting the stationary ring and the
frame.
[0010] The guide blade of the cover extends at about 90 degrees
relative to the runner blade of the impeller. Thus, in operation,
the airflow passes through the guide blades, turns, and impacts the
runner blades at about 90 degrees, which accordingly drives the
active blades to rotate.
[0011] The passive fan assembly of the invention is capable of
effectively using the airflow and promoting the heat-dissipating
efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
[0013] FIG. 1 is a perspective view of the passive fan assembly in
accordance with the invention;
[0014] FIG. 2 is an exploded view of a passive fan assembly of FIG.
1;
[0015] FIG. 3 shows the arrangement of a guide blade and a runner
blade of FIG. 2;
[0016] FIG. 4 is a sectional view of a passive fan assembly in
accordance with the invention;
[0017] FIG. 5A is a velocity diagram of airflow entering a passive
fan assembly, wherein the passive fan assembly has no guide
blades;
[0018] FIG. 5B is a velocity diagram of airflow entering the
passive fan assembly of the invention, wherein the passive fan
assembly has guide blades.
DETAILED DESCRIPTION
[0019] Referring to FIGS. 1, 2 and 4, a passive fan assembly in
accordance with an embodiment of the invention includes a base 1,
an impeller 2 mounted on the base 1, and a cover 3 disposed in
front of the impeller 2 and connected to the base 1.
[0020] The impeller 2 includes a hub 20, a plurality of runner
blades 22 encircling the hub 20, a partition 24 connected to ends
of the runner blades 22, a plurality of active blades 26 encircling
the partition 24, and a rotary shaft 28 axially extending from the
hub 20.
[0021] The base 1 includes a frame 10, a bearing seat 12, a
plurality of ribs 14 connecting the frame 10 and the bearing seat
12, and at least one bearing 16 disposed in the bearing seat 12 for
holding the rotary shaft 28 of the impeller 2. The bearing 16 may
be a bushing bearing, a ball bearing, a magnetic bearing or any
other bearing in which the rotary shaft 28 can be stably rotated.
Furthermore, a plurality of airflow-guiding blades can be
substituted for the ribs 14 in the base 1 to guide airflow.
[0022] The cover 3 includes a frame 30, a stationary part 32, a
plurality of guide blades 34 disposed around the stationary part
32, a stationary ring 36 connected to ends of the guide blades 34,
and a plurality of supporting elements 38 connecting the stationary
ring 36 and the frame 30.
[0023] Referring to FIG. 3, the guide blade 34 of the cover 3 is
approximately perpendicular to the runner blade 22 of the impeller
2. When passing through the guide blade 34, the airflow turns and
impacts the runner blade 22 at about 90 degrees, which drives the
active blades 26 to rotate.
[0024] When the passive fan assembly of the invention is used
together with an airflow-providing system, the cover 3 of the
passive fan assembly is connected to the airflow outlet 4 of an
airflow-generating device (e.g. an axial fan or an air blower) in
the airflow-providing system. In operation, high-pressure airflow
generated by the airflow-generating device entirely enters the
passive fan assembly through the guide blades 34. The guide blades
34 have inclined surfaces to change the direction of the airflow so
that the airflow can effectively impact the runner blades 22 of the
impeller 2.
[0025] The function of the guide blades 34 of the invention can be
clearly explained by referring to FIGS. 5A and 5B. FIG. 5A is a
velocity diagram of airflow entering a passive fan assembly,
wherein the passive fan assembly has no guide blades. The airflow,
generated by an airflow-generating device, is axial high-pressure
airflow and has a velocity V.sub.in. The vector V.sub.2 of velocity
V.sub.in determines the work done by the airflow on the runner
blade 22, while no work is contributed by the vector V.sub.1. It is
therefore understood that a part of kinetic energy of the airflow
is lost. FIG. 5B is a velocity diagram of airflow entering the
passive fan assembly of the invention, wherein the passive fan
assembly has guide blades 34. When the axial airflow passes through
the guide blade 34, the velocity of the axial airflow changes from
V.sub.in to V.sub.in' which is approximately perpendicular to the
runner blade 22. Then, the airflow can fully do work on the runner
blade 22 so that the kinetic energy transferred from the runner
blade 22 to the active blade 26 is maximized. Thus, the
heat-dissipating efficiency of the active blade 26 is significantly
improved.
[0026] In conclusion, the passive fan assembly of the invention is
capable of effectively promoting the energy transfer and providing
a better heat-dissipating efficiency.
[0027] While the invention has been described by way of example and
in terms of preferred embodiment, it is to be understood that the
invention is not limited thereto. To the contrary, it is intended
to cover various modifications and similar arrangements (as would
be apparent to those skilled in the art). Therefore, the scope of
the appended claims should be accorded the broadest interpretation
so as to encompass all such modifications and similar
arrangements.
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