U.S. patent application number 11/263351 was filed with the patent office on 2006-10-26 for aerodynamically enhanced cooling fan.
This patent application is currently assigned to Hewlett-Packard Development Company, L.P.. Invention is credited to John P. Franz, Yousef Jarrah, Wade D. Vinson.
Application Number | 20060237169 11/263351 |
Document ID | / |
Family ID | 37185645 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060237169 |
Kind Code |
A1 |
Franz; John P. ; et
al. |
October 26, 2006 |
Aerodynamically enhanced cooling fan
Abstract
A cooling fan comprising a fan housing that connects to a
chassis supporting an electronic device. A motor is disposed within
the fan housing. A blade assembly is rotatably coupled to the
motor. The fan housing has a length at least 10 mm longer than a
distance between a leading edge and a trailing edge of the blade
assembly.
Inventors: |
Franz; John P.; (Houston,
TX) ; Vinson; Wade D.; (Magnolia, TX) ;
Jarrah; Yousef; (Tuscon, AZ) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Assignee: |
Hewlett-Packard Development
Company, L.P.
Houston
TX
77070-2698
|
Family ID: |
37185645 |
Appl. No.: |
11/263351 |
Filed: |
October 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11111066 |
Apr 21, 2005 |
|
|
|
11263351 |
Oct 31, 2005 |
|
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|
Current U.S.
Class: |
165/104.33 ;
257/E23.088; 257/E23.098; 257/E23.099 |
Current CPC
Class: |
F28D 15/0266 20130101;
H01L 2924/00 20130101; F28F 2250/08 20130101; H01L 2924/0002
20130101; F28D 15/02 20130101; H01L 23/473 20130101; H01L 23/467
20130101; H01L 23/427 20130101; F28D 2021/0029 20130101; F28F 1/14
20130101; H01L 2924/0002 20130101 |
Class at
Publication: |
165/104.33 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Claims
1. A cooling fan comprising: a fan housing that connects to a
chassis supporting an electronic device; a motor disposed within
said fan housing; and a blade assembly rotatably coupled to said
motor, wherein said fan housing has a length at least 10 mm longer
than a distance between a leading edge and a trailing edge of said
blade assembly.
2. The cooling fan of claim 1 wherein the conical hub has a
diameter at least twice its length.
3. The cooling fan of claim 1 wherein said blade assembly is
recessed from an inlet disposed on said housing.
4. The cooling fan of claim 3 wherein said blade assembly is
recessed from the inlet a distance at least equal to a diameter of
said blade assembly.
5. The cooling fan of claim 1 wherein said motor has a length at
least twice its diameter.
6. The cooling fan of claim 1 further comprising a plurality of
stator blades fixably disposed within said housing such that an
airflow generated by said blade assembly passes over said stator
blades.
7. The cooling fan of claim 6 wherein said stator blades have a
backward sweeping trailing edge and the blades of said blade
assembly have a forward swept leading edge.
8. The cooling fan of claim 1 wherein the blades of said blade
assembly have an asymmetrical trailing edge.
9. The cooling fan of claim 1 wherein the blades of said blade
assembly have an expanded mid-section.
10. The cooling fan of claim 1 wherein said fan housing has a
tapered inlet.
11. The cooling fan of claim 1 wherein said fan housing has a
tapered outlet.
12. The cooling fan of claim 1 wherein said fan housing comprises
disturbance reducing ripples disposed near an outlet.
13. A computer system comprising: a chassis; an electronic
component disposed within said chassis; and an aerodynamically
enhanced cooling fan disposed within said chassis, wherein said
cooling fan comprises a fan housing that connects to said chassis,
wherein said fan housing said fan housing has a length at least 10
mm longer than a distance between a leading edge and a trailing
edge of a blade assembly disposed within the housing.
14. The computer system of claim 13 wherein the blade assembly is
rotatably coupled to a motor and comprises a plurality of blades
extending radially from a conical hub having a diameter at least
twice its length.
15. The computer system of claim 13 wherein said blade assembly is
recessed from an inlet disposed on said housing a distance at least
equal to a diameter of said blade assembly.
16. The computer system of claim 13, wherein said aerodynamically
enhanced cooling fan comprises further comprises a plurality of
stator blades fixably disposed within said housing such that an
airflow generated by said blade assembly passes over said stator
blades.
17. The computer system of claim 13, wherein said fan housing has a
tapered inlet and a tapered outlet.
18. A cooling fan comprising: means for connecting the fan to a
chassis supporting an electronic device; means for rotating a blade
assembly; and means for reducing pressure disturbances in a flow of
air through the fan, wherein said means for reducing pressure
disturbances comprises a fan housing having a length at least 10 mm
longer than a distance between a leading edge and a trailing edge
of the blade assembly.
19. The cooling fan of claim 18 wherein said means for reducing
pressure disturbances comprises at least one aerodynamic
enhancement to the blade assembly selected from the group
consisting of a blade having a sweeping edge, a blade having an
asymmetrical edge, and a blade having an expanded mid-section.
20. The cooling fan of claim 18 wherein said means for reducing
pressure disturbances comprises an aerodynamic enhancement to the
fan housing selected from the group consisting of a tapered inlet,
a tapered outlet, and ripples in an edge of the housing at an
outlet.
Description
BACKGROUND
[0001] Computer systems include numerous electrical components that
draw electrical current to perform their intended functions. For
example, a computer's microprocessor or central processing unit
("CPU") requires electrical current to perform many functions such
as controlling the overall operations of the computer system and
performing various numerical calculations. Generally, any
electrical device through which electrical current flows produces
heat. The amount of heat any one device generates generally is a
function of the amount of current flowing through the device.
[0002] Typically, an electrical device is designed to operate
correctly within a predetermined temperature range. If the
temperature exceeds the predetermined range (i.e., the device
becomes too hot or too cold), the device may not function
correctly, thereby potentially degrading the overall performance of
the computer system. Thus, many computer systems include cooling
systems to regulate the temperature of their electrical components.
One type of cooling system is a forced air system that relies on
one or more cooling fans to blow air over the electronic components
in order to cool the components.
[0003] The cubic feet per minute ("CFM") of air that can be moved
across an electric device is an important factor in how much heat
can be removed from the device. Thus, the capacity of a cooling fan
is a critical factor in selecting an air mover for use in a cooling
application. The CFM that a cooling fan can produce is governed a
number of factors including: the total area of the blades
generating the airflow, the free area provided for airflow through
the fan, the design of the blades, and the power generated by the
electric motor.
[0004] Axial flow fans generally comprise a plurality of radial
blades rotating within a housing. Increasing performance demands on
axial flow fans have required that fans provide increased volumes
of air while, at the same time, reducing the size of the fan. One
solution to increasing fan performance is simply to increase the
speed at which the fan rotates. Increasing fan speed can also be
accompanied by increased acoustic emissions, increased vibration,
and decreased component life. Therefore, as can be appreciated,
there remains a need in the art for cooling fans that provide high
volumes of airflow by designs and improvements that increase
performance without necessitating an increase in the speed at which
fan operates.
BRIEF SUMMARY
[0005] The problems noted above are solved in large part by a
cooling fan comprising a fan housing that connects to a chassis
supporting an electronic device. A motor is disposed within the fan
housing. A blade assembly is rotatably coupled to the motor. The
fan housing has a length at least 10 mm longer than a distance
between a leading edge and a trailing edge of the blade
assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] For a detailed description of exemplary embodiments of the
invention, reference will now be made to the accompanying drawings
in which:
[0007] FIG. 1 shows a computer system including cooling fans
constructed in accordance with embodiments of the invention;
[0008] FIG. 2 shows a cross-sectional view of a cooling fan having
a conical hub constructed in accordance with embodiments of the
invention;
[0009] FIG. 3 shows a cross-sectional view of cooling fan having an
extended intake as constructed in accordance with embodiments of
the invention;
[0010] FIG. 4 shows a cross-sectional view of cooling fan having an
extended length motor constructed in accordance with embodiments of
the invention;
[0011] FIG. 5 shows a cross-sectional view of cooling fan having
aerodynamically optimized stator blades constructed in accordance
with embodiments of the invention;
[0012] FIG. 6 shows a cross-sectional view of cooling fan having
forward swept blades as constructed in accordance with embodiments
of the invention;
[0013] FIG. 7 shows a cross-sectional view of cooling fan having an
asymmetric trailing edge constructed in accordance with embodiments
of the invention;
[0014] FIG. 8 shows a cross-sectional view of cooling fan having a
variable chord length constructed in accordance with embodiments of
the invention;
[0015] FIG. 9 shows a cross-sectional view of cooling fan having an
extended housing constructed in accordance with embodiments of the
invention; and
[0016] FIG. 10 shows a cooling fan having a rippled housing
constructed in accordance with embodiments of the invention.
NOTATION AND NOMENCLATURE
[0017] Certain terms are used throughout the following description
and claims to refer to particular system components. As one skilled
in the art will appreciate, computer companies may refer to a
component by different names. This document does not intend to
distinguish between components that differ in name but not
function. In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ." Also, the term "couple" or "couples" is intended to mean
either an indirect or direct connection. Thus, if a first device
couples to a second device, that connection may be through a direct
connection, or through an indirect connection via other devices and
connections.
DETAILED DESCRIPTION
[0018] The following discussion is directed to various embodiments
of the invention. Although one or more of these embodiments may be
preferred, the embodiments disclosed should not be interpreted, or
otherwise used, as limiting the scope of the disclosure, including
the claims. In addition, one skilled in the art will understand
that the following description has broad application, and the
discussion of any embodiment is meant only to be exemplary of that
embodiment, and not intended to intimate that the scope of the
disclosure, including the claims, is limited to that
embodiment.
[0019] Many computer cooling applications utilize cooling fans that
have been designed to minimize the size of the fan. This design
methodology results in small fans that face performance
limitations, have inherent aerodynamic inefficiencies, and unwanted
acoustic emissions. The embodiments described herein illustrate
aerodynamic enhancements that can be made to a cooling fan in order
to improve performance, efficiency, and/or acoustic emissions. Many
of the embodiments described herein will utilize more space than a
conventional fan design but the increase in size can be offset by
an increase in efficiency of the fan. As it is used herein, an
aerodynamically enhanced cooling fan is a cooling fan used in an
electronics cooling application that has been designed for
aerodynamic performance as opposed to compactness. Aerodynamically
enhanced cooling fans are characterized by features that improve
aerodynamic performance but also increase the length of the fan
including, but not limited to, a conical hub, a recessed blade
assembly, an elongated motor, stator and impeller blades, shaped
blades, tapered inlet, tapered outlet, and other features that
reduce pressure disturbances.
[0020] Referring now to FIG. 1, a computer assembly 10 comprises
chassis 12, motherboard 14, heat sinks 16, electronic components
18, and aerodynamically enhanced cooling fans 20. Each
aerodynamically enhanced cooling fan 20 comprises a housing 22 that
extends past and surrounds blade assembly 24. Cooling fans 20 are
arranged so as to generate an airflow that cools electronic
components 28. Heat sinks 26 may be arranged so as to be directly
in the airflow generated by fans 20. Heat sinks 26 are coupled to
electronic components so that the heat generated by the electronic
component is dissipated to the airflow through the increased
surface area of the heat sink.
[0021] Cooling fans 20 comprise features that improve the
performance of the fan but also increase the length of the fans as
compared to conventional fans having the same diameter blades.
Conventional fans often maximize the area of the blades by
extending the blades to the edge of the housing. Cooling fans 20
incorporate one or more aerodynamic improvements that necessitate
the housing 22 extending past the leading edge and/or the trailing
edge of the blades. In certain embodiments, housing 22 has a length
that is at least 10 mm longer than the distance between the leading
edge and the trailing edge of the blades.
[0022] FIG. 2 illustrates cooling fan 100 comprising housing 102,
blades 104, and conical hub 106. Conical hub 106 projects in front
of blades 104 and provides a smooth transition that eliminates
pressure disturbances within the flow moving toward the blades.
This smooth transition increases pressure performance of the fan.
In certain embodiments, hub 106 has length 107 at least twice its
diameter 108. Hub 106 may have a smoothly curved tip 109 or may
have a more sharply pointed tip but avoids any flat surfaces or
abrupt corners that may cause disturbances in the flow. Housing 102
also projects in front of blades 104 so that conical hub 106 is
also surrounded by the housing.
[0023] FIG. 3 illustrates cooling fan 110 comprising housing 112
and blade assembly 114 that is recessed from housing inlet 116.
Blade assembly 114 is recessed a distance 117 of at least one blade
diameter 118 from inlet 116. In certain embodiments, a recessed
distance 117 of at least two blade diameters 118 is desired.
Recessing blade assembly 114 reduces flow disruptions and pressure
disturbances at inlet 116 by allowing the flow to straighten and
stabilize before contacting the blade assembly. Reducing the flow
disruptions also aids in reducing acoustic emissions.
[0024] FIG. 4 illustrates cooling fan 120 comprises housing 122,
motor 124, and blades 126. The motor diameter 125 is limited by the
diameter of hub 121. In order to increase the power provided by
motor 124, the length 127 of the motor can be increased. Thus,
motor 124 can have a smaller diameter 125 and longer length 127
than a motor with equivalent power in a conventional fan. In
certain embodiments, motor 124 has a length at least twice as long
as its diameter. Housing 122 extends past the trailing edge of
blades 126 so as to surround motor 124. Reducing diameter 125
allows for a reduction in the diameter of hub 121 and a greater
area within housing 122 for the surface area of blades 126.
Increasing the surface area of blades 126 increases the
differential pressure that can be developed by the fan.
[0025] FIG. 5 illustrates cooling fan 130 comprising housing 132,
motor 134, impeller blades 136 and stator blades 138. Stator blades
138 are offset from impeller blades 136 so that flow moves
efficiently between the trailing edge of the impeller blades to the
leading edge of the stator blades. The performance of cooling fan
130 may also be improved by impeller blades 136 having a forward
swept leading edge 140 and stator blades 138 having a backward
sweeping trailing edge 142. FIG. 6 illustrates one shape of a blade
144 having a sweeping edge 146. Other examples of variations in
blade shapes are shown in FIGS. 7 and 8. FIG. 7 illustrates a blade
150 having an asymmetrical edge 152. FIG. 8 illustrates a blade 160
having an expanded mid-section 162.
[0026] In certain embodiments, multiple blade designs may be used
in combination on a single impeller assembly. The number of blades
used may also be varied depending on factors such as the speed at
which the fan will be operated. These, and various other blade
designs and configurations, seek to improve aerodynamic performance
of the blades so as to increase fan performance and/or decrease
acoustic emissions. It is also understood that the blade designs
described herein can be used with other fan configurations,
including conventionally sized cooling fans.
[0027] Aerodynamic improvements may also be realized by varying the
configuration of a fan housing. FIG. 9 illustrates a cooling fan
170 having a tapered inlet 172 and a tapered outlet 174. Tapered
inlet 172 acts to converge the flow moving toward blades 176. The
convergence of flow through tapered inlet 172 increases the
pressure of the flow as it approaches blades 176 and allows the fan
to operate at a higher pressure. Tapered inlet 172 also provides a
smooth, gradual transition that can reduce acoustic emissions by
reducing sudden pressure disturbances. Pressure disturbances can
also cause pressure losses that reduce the efficiency of the fan.
Therefore, reducing sudden pressure disturbances may help to reduce
acoustic emissions and increase the efficiency of the fan by
reducing losses caused by the pressure disturbances.
[0028] On the opposite end of fan 170, outlet 174 provides a
gradual transition in diameter that allows the flow to smoothly
expand as it moves away from blades 176. The smooth, gradual
transition can help reduce acoustic emissions by reducing sudden
pressure disturbances. Pressure disturbances can also cause
pressure losses that reduce the efficiency of the fan. Therefore,
reducing sudden pressure disturbances may help to reduce acoustic
emissions and increase the efficiency of the fan by reducing losses
caused by the pressure disturbances.
[0029] In another embodiment, as shown in FIG. 10, housing 180 may
have "ripples" 182 near the edges of the housing. Ripples 182
reduce sudden pressure disturbances in the flow as it exits housing
180. Pressure disturbances can cause unwanted acoustic emissions
may create pressure losses that reduce the efficiency of the fan.
Therefore, reducing sudden pressure disturbances may help to reduce
acoustic emissions and increase the efficiency of the fan by
reducing losses caused by the pressure disturbances.
[0030] The above discussion is meant to be illustrative of the
principles and various embodiments of the present invention.
Numerous variations and modifications will become apparent to those
skilled in the art once the above disclosure is fully appreciated.
For example, the aerodynamic features described herein may be
applied to other types of axial fans used to cool electronic
components. It is intended that the following claims be interpreted
to embrace all such variations and modifications.
* * * * *