U.S. patent application number 09/915857 was filed with the patent office on 2003-01-30 for enhanced performance air moving assembly.
Invention is credited to Belady, Christian L., Giraldo, Mike Devon, Simon, Glenn C., Zeighami, Roy M..
Application Number | 20030021674 09/915857 |
Document ID | / |
Family ID | 25436352 |
Filed Date | 2003-01-30 |
United States Patent
Application |
20030021674 |
Kind Code |
A1 |
Zeighami, Roy M. ; et
al. |
January 30, 2003 |
ENHANCED PERFORMANCE AIR MOVING ASSEMBLY
Abstract
The air moving assembly includes at least one air moving device
and a stator, said stator being operable to at least reduce one
expansion and/or one contraction for airflow passing through the
assembly. The stator is also preferably operable to impart or
adjust swirl for airflow passing through the stator. In at least
one embodiment, the imparted or adjusted swirl rotates in a
direction opposite to that of the rotation of an impeller of the
air moving device. As a result, in at least one embodiment, airflow
exiting the air assembly has no rotational component. The air
moving assembly may include additional air moving devices and/or
stators. In at least one embodiment, the air moving assembly
includes first and second air moving assemblies coupled to a shared
strut assembly.
Inventors: |
Zeighami, Roy M.; (Plano,
TX) ; Belady, Christian L.; (McKinney, TX) ;
Giraldo, Mike Devon; (Dallas, TX) ; Simon, Glenn
C.; (Auburn, CA) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P.O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
25436352 |
Appl. No.: |
09/915857 |
Filed: |
July 26, 2001 |
Current U.S.
Class: |
415/119 ;
415/199.5; 415/211.2 |
Current CPC
Class: |
F04D 29/544 20130101;
F04D 25/166 20130101 |
Class at
Publication: |
415/119 ;
415/199.5; 415/211.2 |
International
Class: |
F04D 029/54 |
Claims
What is claimed is:
1. An air moving assembly operable to generate a flow of air
comprising: an air moving device; and a stator; wherein said stator
is operable to at least reduce one expansion or one contraction of
airflow passing through said assembly.
2. The assembly of claim 1 wherein said stator is operable to at
least reduce one expansion and one contraction of airflow passing
through said assembly.
3. The assembly of claim 2 wherein said stator is operable to
eliminate one expansion and one contraction of airflow passing
through said assembly.
4. The assembly of claim 1 wherein the annular area of a surface of
said stator matches the annular area of a surface of said air
moving device.
5. The assembly of claim 4 wherein the annular area of another
surface of said stator matches the annular area of a surface of
another component of said air moving assembly.
6. The assembly of claim 5 wherein said annular area of said
surface of said air moving device is different from said annular
area of said surface of said another component of said air moving
assembly.
7. The assembly of claim 1 wherein said assembly further includes
at least another air moving device.
8. The assembly of claim 1 wherein said stator is further operable
to alter the rotational direction of swirl for airflow passing
through said stator.
9. The assembly of claim 1 wherein said stator is further operable
to impart swirl having a rotational direction opposite to that of a
direction of rotation of an impeller of said air moving device.
10. The assembly of claim 1 wherein said stator includes one or
more curved blades.
11. The assembly of claim 1 wherein said stator includes more
blades than said air moving device.
12. The assembly of claim 1 wherein said stator is part of a
fingerguard of said air moving device.
13. The assembly of claim 1 wherein said assembly is incorporated
into an electronic device.
14. An air moving device operable to generate a flow of air, said
device comprising: a strut assembly; a first air moving assembly
coupled to said strut assembly; and a second air moving assembly
coupled to said strut assembly; wherein said strut assembly
includes a stator, said stator being operable to at least reduce
one expansion or one contraction of airflow passing through said
air moving device.
15. The device of claim 14 wherein said stator is operable to at
least reduce one expansion and one contraction of airflow passing
through said air moving device.
16. The device of claim 14 wherein said first air moving assembly
and said second air moving assembly are synchronized such that
acoustic beat frequencies are limited.
17. The device of claim 14 wherein said device is operable such
that when said first air moving assembly fails, the rotational
velocity of an impeller of said second air moving assembly is
increased.
18. A stator for improving the performance of an air moving system,
said stator comprising: a frame; and at least one blade coupled to
said frame; wherein said stator is operable to at least reduce one
expansion or one contraction of airflow passing through said
cooling system.
19. The stator of claim 18 wherein said stator is further operable
to convert a tube axial fan to a vane axial fan.
20. The stator of claim 18 wherein said stator is a drop-in module
operable to be inserted between two air moving devices of an N+1
series configuration.
Description
RELATED APPLICATION
[0001] This application is related to U.S. patent application Ser.
No. 09/867,194 entitled, "ENHANCED PERFORMANCE FAN WITH THE USE OF
WINGLETS" filed May 29, 2001, the disclosure of which is hereby
incorporated by reference herein.
TECHNICAL FIELD
[0002] The present invention relates to systems and methods for
aerodynamic flow, and more particularly to an enhanced performance
air moving assembly and the components thereof.
BACKGROUND
[0003] Air moving devices such as fans and blowers are an important
aspect of cooling systems, such as the cooling systems employed in
today's electronic devices (e.g., computer devices such as central
processing units (CPUs), storage devices, server devices, video
cards). In the case of electronic devices, such air moving devices
are typically used to push and/or draw air across heat sinks, as
well as to remove waste heat from components of the electronic
devices. Moreover, in addition to developing airflow through an
electronic device, the fans, blowers, etc., must overcome system
back pressure, which is the pressure lost due to aerodynamic
resistance at the device. System back pressure depends upon such
things as the number of heat sinks in the device, as well as the
number of other components in the device.
[0004] Reliability is desired for the fans, blowers, etc., employed
in the above mentioned cooling applications, especially for high
end electronic devices, because when one fan fails, typically the
remaining fans are unable to provide enough flow to compensate for
the non-functioning fan. Unfortunately, these fans, etc., have high
failure rates, most often on account of bearing failures. For this
reason, most system designers employ N+1 fan configurations to
compensate for the failure of a single fan. Examples of N+1 system
designs are illustrated in FIGS. 1A and 1B.
[0005] N+1 configurations have two expected benefits. First, in N+1
configurations, if one fan fails, a redundant fan continues to push
air through the system, thereby increasing the reliability of the
cooling system. Secondly, for N+1 series configurations,
particularly the configuration of FIG. 1B, if both the N and +1
fans are operating, theoretically, double the pressure should be
provided by the two fans in series compared to that provided by a
single fan (assuming the pressures are additive).
[0006] However, rarely, if ever, does the second expected benefit
occur. One reason for this is that airflow exiting the first fan
normally has some "swirl", meaning that the velocity of the airflow
has a rotational component, as well as an axial component. This
phenomena is illustrated in FIG. 2. As can be seen in FIG. 2,
airflow entering fan 210 has a velocity represented in FIG. 2 by
velocity vector 200. After passing through fan 210, velocity vector
200 develops both an axial component 220 and a rotational component
230. The swirl provided by first fan 210 normally degrades the
performance of second fan 240. One reason for this is that
typically the airflow exiting first fan 210 is swirling in the same
direction as the rotation of the blades of second fan 240. As a
result, the rotational speed of the blades of second fan 240 is
effectively decreased.
[0007] In addition to the above, N+1 configurations have other
notable disadvantages, to include the significant space required to
implement N+1 configurations. Oftentimes, a desired design for an
electronic device and/or cooling system does not leave adequate
space for an N+1 configuration. As a result, cooling system designs
and/or electronic device designs must be compromised to accommodate
an N+1 configuration.
[0008] Another disadvantage of prior art air moving assemblies are
losses due to the expansion and contraction of airflow as air
passes through the assemblies.
[0009] Also included among the disadvantages of N+1 configurations
is the fact that if one fan fails, the non-functioning fan creates
a large impedance (i.e., airflow obstruction) in the cooling
system. Therefore, two fans in series with one fan not working is
worse for the cooling system then one fan by itself.
[0010] Another undesirable side effect of N+1 configurations is
unwanted noise, to include acoustic beat frequencies.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to an enhanced performance
air moving assembly. In one embodiment, the air moving assembly
includes a first air moving device (e.g., a fan, a blower) and a
stator, the stator being operable to at least reduce one expansion
and/or one contraction of airflow passing through the assembly.
Preferably, the stator is also operable to impart to or adjust
swirl for airflow passing through said stator. In at least one
embodiment, the stator imparts or adjusts a certain swirl such that
upon exiting the air moving assembly, the airflow has little or no
swirl. Furthermore, various embodiments of the air moving assembly
of the present invention include more than one air moving device
and/or more than one stator. In at least one embodiment, the air
moving assembly of the present invention is employed in cooling
applications for electronic devices.
[0012] Moreover, in at least one embodiment, the air moving
assembly includes a first air moving apparatus, as well as a second
air moving apparatus, coupled to a strut assembly. In at least one
of these embodiments, the strut assembly includes a stator operable
to reverse the direction of swirl of the airflow exiting the first
air moving apparatus.
[0013] It should be recognized that one technical advantage of one
aspect of at least one embodiment of the present invention is that
undesirable swirl normally hampering the efficiency of prior art
air moving devices is counteracted, resulting in a higher
performance air moving device. In addition, certain losses
experienced in prior art systems, such as expansion and contraction
losses, are reduced (and in some instances, eliminated) in various
embodiments of the present invention. Moreover, in at least one
embodiment of the present invention, valuable device space is saved
by the sharing of components between air moving devices (e.g.,
shared strut assembly). Furthermore, in at least one embodiment,
the air moving assembly of the present invention helps compensate
for, at least in part, the impedance resulting from a
non-functioning fan (i.e., the failed fan state). In addition, in
at least one embodiment, acoustic beat frequencies are limited by
the present invention.
BRIEF DESCRIPTION OF THE DRAWING
[0014] FIG. 1A depicts an exemplary N+1 parallel fan system
configuration;
[0015] FIG. 1B depicts an exemplary N+1 series fan system
configuration;
[0016] FIG. 2 depicts the swirl phenomena experienced by airflow
passing through an exemplary fan;
[0017] FIG. 3A depicts an exemplary embodiment of an air moving
assembly in accordance with the present invention;
[0018] FIG. 3B depicts the alterations experienced by airflow
passing through the air moving assembly of FIG. 3A;
[0019] FIG. 4 depicts an exemplary embodiment of a fan that may be
employed in the fan assembly of FIG. 3A;
[0020] FIG. 5A depicts a first exemplary embodiment of a stator in
accordance with the present invention;
[0021] FIG. 5B depicts a second exemplary embodiment of a stator in
accordance with the present invention;
[0022] FIG. 5C depicts a third exemplary embodiment of a stator in
accordance with the present invention;
[0023] FIG. 5D depicts a fourth exemplary embodiment of a stator in
accordance with the present invention; and
[0024] FIG. 6 depicts a second exemplary embodiment of an air
moving assembly of the present invention.
DETAILED DESCRIPTION
[0025] FIG. 3A depicts an exemplary embodiment of an air moving
assembly of the present invention. In the embodiment of FIG. 3A,
airflow having a certain velocity, represented by velocity vector
310 in FIG. 3A, passes through fan 320 of fan assembly 300. As a
result of passing through fan 320, velocity vector 310 develops
both an axial component 340 and a rotational component 350 (also
referred to as "swirl" or radial velocity). In the embodiment of
FIG. 3A, the blades of fan 320 rotate in a clockwise direction.
Therefore, rotational component 350 is a clockwise rotational
component.
[0026] At some point after passing through fan 320, the airflow
passes through stator 380 and is altered. In a preferred
embodiment, the direction of the rotational component is reversed.
Accordingly, after passing through stator 380, velocity vector 310
of the airflow has an axial component 360 and a counter-clockwise
rotational component 370.
[0027] After passing through stator 380, the airflow passes through
fan 330. In the embodiment of FIG. 3, the blades of fan 330 rotate
in the same direction as that of fan 320. In a preferred
embodiment, after passing through fan 330, the velocity of the
airflow includes only axial component 390, i.e., possesses no
rotational component. The removal of the rotational component of
the airflow facilitated by the difference in the direction of
rotation between the airflow entering fan 330 and the blades of fan
330 is desirable, at least in part, because by removing the
rotational component, the kinetic energy associated with the swirl
is converted into potential energy in terms of a desired increase
in pressure.
[0028] FIG. 3B provides a top-down perspective of the effects of
fans 320 and 330, as well as stator 380, on airflow passing through
assembly 300. In FIG. 3B, airflow entering fan 320 has a velocity
represented by velocity vector 310. As can be seen, upon entering
fan 320, the velocity of the airflow has only axial component Va.
However, while the airflow passes through fan 320, rotating blades
325-1, 325-2, and 325-n (representing the blades of fan 320)
deflect the airflow into a helical motion thereby accelerating the
velocity such that when the airflow exits the blades of fan 320,
the velocity of the airflow has increased from V.sub.a to
V.sub.total. V.sub.total includes axial component V.sub.a, as well
as a rotational component (V.sub.r) and a given swirl angle (angle
.theta.) (swirl angle being the angle of rotation of the airflow).
As shown, blades 325-1, 325-2, and 325-n (representing the blades
of fan 320) rotate in a clockwise direction. Therefore, in the
embodiment of FIG. 3B, V.sub.r has a clockwise direction.
[0029] At some point after exiting the blades of fan 320, the
airflow passes through stator 380, as a result of which, V.sub.r
for the airflow is altered. In particular, while passing through
stator 380, the airflow follows the contour lines of stator blades
385-1, 385-2, and 385-n (representing the stator blades of stator
380) such that when the airflow exits stator 380, the direction of
V.sub.r is reversed.
[0030] In the embodiment of FIG. 3B, after exiting stator 380, the
airflow passes through blades 335-1, 335-2, and 335-n (representing
the blades of fan 330). As can be seen, blades 335-1, 335-2, and
335-n rotate in a clockwise direction. Therefore, the rotation of
the blades of fan 330 deflect the airflow back into a more or less
axial direction thereby decreasing the air velocity from
V.sub.total to V.sub.a (i.e., the airflow exits the blades of fan
330 having only an axial component). As discussed earlier, although
the velocity of the airflow is decreased, the total pressure is
increased.
[0031] Referring back to FIG. 3A, fans 320 and 330 may be any one
of several fans or other air moving devices, now known or later
developed, to include a propeller fan, tube axial fan, vane axial
fan, centrifugal fan, axial-flow fan, forward curved wheel blower,
backward curved wheel blower, squirrel cage blower, and the like.
In at least one embodiment of fan assembly 300, the structure of
fan 330 is identical to that of fan 320 However, it will be
appreciated that the structure of fan 330 may be different from
that of fan 320.
[0032] FIG. 4 depicts an exemplary embodiment of fan 400 that may
be employed as fan 320 and/or fan 330. Fan 400 includes motor
assembly 470. Coupled to motor assembly 470 is impeller 480. In at
least one embodiment, impeller 480 includes hub 410 and one or more
blades integrated therewith or attached thereto (the one or more
blades represented by blades 420-1 and 420-n in FIG. 4). In at
least one embodiment, assembly 470, along with impeller 480, is
disposed within, and, preferably, secured to base 440 that includes
an open interior region spanned by struts 490. Struts 490 support a
central location 430 to which assembly 470, as well as impeller
480, are mounted. In at least one embodiment, base 440 further
includes stationary venturi (not shown) having an inner surface
that, in a known manner, typically resembles an airfoil
rotationally symmetric about hub 410, which is closely spaced
radially beyond the distal ends of rotating blades 420-1 and 420-n.
Moreover, preferably, attached to or integrated with base 440 is
first finger guard 450 and second finger guard 460. Furthermore,
blades 420-1 and 420-n may include winglets as discussed in U.S.
patent application Ser. No. 09/867,194, previously incorporated by
reference herein.
[0033] FIGS. 5A and 5B depict exemplary embodiments of stator 380.
In the embodiment of FIG. 5A, stator 380 includes frame 520, which
itself includes rectangular outer surface 530 and rectangular inner
surface 540. Also included in the embodiment of FIG. 5A is stator
hub 500. Coupled to hub 500 and frame 520 (e.g., integrated
therewith) are one or more stator blades (also referred to as guide
vanes), such as blades 510-1 and 510-n. Hub 500 and blades 510-1
and 510-n are stationary, i.e, do not rotate around the center axis
of hub 500. Furthermore, the stator blades are straight blades,
meaning the chord line for each of the blades is straight (chord
line being the line joining the centers of the leading edge and
trailing edge of the blade). In at least one embodiment, one or
more of the edges of blades 510-1 and 510-n are rounded to improve
aerodynamics. Moreover, in at least one embodiment, the stator
blades have an airfoil shape.
[0034] In the embodiment of FIG. 5B, similar to FIG. 5A, stator 380
includes frame 550. However, unlike frame 520, frame 550 includes
rectangular outer surface 560 and circular inner surface 570. Also
included in stator 380 (FIG. 5B) is stator hub 580. Coupled to
and/or integrated with hub 580 and frame 550 are one or more stator
blades, such as blades 590-1 and 590-n. Hub 580 and blades 590-1
and 590-n are stationary, i.e, do not rotate around the center axis
of hub 580. Moreover, unlike the stator of FIG. 5A, the stator
blades of FIG. 5B are curved blades, meaning the chord lines for
the blades are curved.
[0035] In at least one embodiment, stator 380 is operable to at
least reduce (preferably eliminate) one expansion and/or one
contraction of air flow passing through assembly 300. In one
embodiment, stator 380 at least reduces (preferably eliminates) one
expansion and/or one contraction by virtue of having a surface
whose annular area matches that of a surface(s) of fan 320 and/or
fan 330. In addition, in at least one embodiment, the annular area
of the hub of stator 380 is matched to that of the hub of fan 320
and/or fan 330 to reduce or preferably eliminate expansion and/or
contraction as well. Moreover, in at least one embodiment, the
thickness of stator 380 is on the same order as that of fans 320
and 330.
[0036] In addition, in at least one embodiment, the annular area of
a first surface of stator 380 matches that of a surface of one
component of assembly 300, while the annular area of a second
surface of stator 380 matches that of a surface of another
component of assembly 300, the surface of the later described
component having an annular area different from that of the surface
of the earlier described component. For example, FIG. 5C depicts a
side-view of an embodiment of stator 380 disposed between fan 330
and air duct 395. Fan 330 may be at the inlet or outlet of duct
395. As can be seen, the annular area of at least one surface of
fan 330 is different from that of at least one surface of air duct
395. To reduce (preferably, eliminate) at least one expansion
and/or one contraction of the airflow passing through assembly 300,
the annular area of at least one surface of stator 380 matches that
of fan 330, while the annular area of at least another surface of
stator 380 matches that of air duct 395. As part of this matching,
in the embodiment of FIG. 5C, the inner surface of stator 380
tapers from the annular area of a surface of fan 330 to the annular
area of a surface of air duct 395. In the embodiment of FIG. 5D,
not only is an inner surface of stator 380 tapered, but an outer
surface is as well. The stator blades of stator 380 (not shown in
FIGS. 5C and 5D) are disposed somewhere within the interior region
spanned by the tapered interior surface. Although in FIGS. 5C and
5D the inner surface of stator 380 tapers from the annular area of
a surface of a component to the right of fan 330 to that of a
surface of a component to its left, it will be appreciated that in
some embodiments, the opposite is true.
[0037] Preferably, the number of stator blades included in stator
380 is greater than the number of fan blades included in fan 320
and/or fan 330. The preferred number of blades for a particular
embodiment of stator 380 depends upon the desired effect of stator
380 on the airflow passing therethrough. One way to determine the
preferred number of blades is to experiment with the number of
blades until the desired effect is achieved.
[0038] Similarly, the blade angle for one or more of the blades of
stator 380 depends upon the desired effect of an embodiment of
stator 380 on the airflow passing therethrough (blade angle being
the angle between the chord line of a blade and the plane of the
axial direction of the airflow). For example, as discussed above,
for at least one embodiment, it is desired that stator 380 reverses
the direction of the rotational component of the velocity of the
airflow passing therethrough. Therefore, in such an embodiment, the
preferred blade angle for one or more blades of stator 380 is the
blade angle which facilitates the reversal of the direction of the
rotational component.
[0039] The suitable blade angle(s) to accomplish the above may be
determined in more than one manner. As non-limiting examples, the
appropriate blade angle(s) to facilitate the desired effect of
stator 380 upon the airflow may be determined: through experimental
measurement (which may include computer simulation) of the airflow
exiting stator 380 and/or fan assembly 300 for various iterations
of the blade angles of the blades of stator 380; through
experimental measurement (which may include computer simulation) of
a mechanical mockup of fan assembly 300; through calculation of the
blade angle using airflow network methods; and/or calculation of
the blade angle using computational fluid dynamics software. In one
embodiment, as part of one or more of the above methods or a
different method altogether, the swirl angle of the air flow
entering stator 380 is determined using the following formulae: 1
axial velocity = volumetric flow rate ( f 3 / m ) area ( f 2 )
radial velocity = ( 233 .times. 10 5 ) .times. ( static pressure (
inches of water column ) ) ( speed of fan ( rpm ) ) .times. (
radius of fan blade ) ) swirl angle=tan.sup.-1[radial
velocity/axial velocity]
[0040] The swirl angle may then be used to determine suitable blade
angles for achieving the desired effect on the rotational
component. Moreover, in at least one embodiment, determining the
desired blade angle(s) involves, at least in part, determination of
the operating point of fan 320 and/or fan 330.
[0041] Moreover, the curvature of one or more of the blades of
stator 380 depends upon the desired effect of an embodiment of
stator 380 on the airflow passing therethrough. As mentioned, for
at least one embodiment, it is desired that stator 380 reverses the
direction of the rotational component of the velocity of the
airflow passing therethrough. Therefore, in such an embodiment, the
preferred curvature for one or more blades of stator 380 is the
curvature which facilitates the reversal of the direction of the
rotational component.
[0042] Furthermore, similar to earlier discussions, suitable
curvature for one or more blades of stator 380 may be determined:
through experimental measurement (which may include computer
simulation) of the airflow exiting stator 380 and/or fan assembly
300 for various iterations of the curvature of one or more blades
of stator 380; through experimental measurement (which may include
computer simulation) of a mechanical mockup of fan assembly 300;
through calculation of curvature using airflow network methods;
and/or calculation of the curvature using computational fluid
dynamics software. Furthermore, in at least one embodiment, the
curvature of the blades of stator 380 are matched to the swirl
angle of the airflow exiting fan 320 in order to produce the
desired effect.
[0043] In one embodiment, stator 380 is fabricated from sheet
metal. In an alternative embodiment, stator 380 is formed via
injection molding. In one of these embodiments, the frame, hub, and
blades are formed as separate parts and than coupled together. In
another embodiment, the frame, hub, and blades are formed as one
piece. In at least one embodiment, stator 380 may be formed from
some combination of the above.
[0044] In at least one embodiment, stator 380 is a drop-in module
that may be inserted between two fans of an N+1 series fan
configuration so as to increase the performance of an N+1 series
fan configuration. Moreover, in at least one embodiment, stator 380
may be employed with (e.g, coupled to or inserted before or after)
a known air moving device to increase the performance of the
device. For example, stator 380 may be employed with a tube axial
fan to effectively create a vane axial fan.
[0045] It will be appreciated that the configurations of stator 380
depicted in FIGS. 5A and 5B are by way of example only, for stator
380 may have numerous other configurations. For example, frame 520
may have a circular inner surface. Similarly, frame 550 may have a
rectangular inner surface. Moreover, frame 520 and/or frame 550 may
have both a circular outer surface and circular inner surface, or
some shape other than a rectangle or circle. In addition, rather
than being implemented as a hub-and-blade configuration, as
depicted in FIGS. 5A and 5B, stator 380 may instead have a
honeycomb configuration.
[0046] Not only are the configurations of stator 380 depicted in
FIGS. 5A and 5B by way of example only, but the configuration of
fan assembly 300 depicted in FIG. 3A is as well, for fan assembly
300 may have several configurations. For example, fan assembly 300
may include a greater number of fans and stators than that depicted
in FIG. 3A. For instance, in one embodiment, airflow passing
through fan assembly 300 may pass through a stator(s) prior to
entering fan 320. Similarly, in one embodiment, airflow passing
through fan assembly 300 may pass through a stator(s) after exiting
fan 330. Moreover, fan assembly 300 may include components other
than those depicted in FIG. 3A.
[0047] Note that, the distance between fan 320 and stator 380
and/or the distance between stator 380 and fan 330 in FIG. 3A is by
way of example only, for the distance between fan 320, fan 330, and
stator 380 may be smaller or greater than that depicted in FIG. 3A.
In fact, in at least one embodiment, stator 380 is incorporated
into a finger guard of fan 320 and/or fan 330. Moreover, in one
embodiment, fan assembly 300 includes a combination of one or more
stand alone stators and one or more finger guard stators. In
addition, in at least one embodiment, stator 380 is coupled to fan
320 and/or fan 330.
[0048] In at least one embodiment, assembly 300 includes a fewer
number of fans than that depicted in FIG. 3A. For example, in at
least one embodiment, assembly 300 does not include fan 320. In at
least one of these embodiments, stator 380 introduces swirl onto
the airflow whose direction of rotation is the opposite of the
direction of the rotation of the blades of fan 330. As a result, in
a preferred embodiment, airflow exiting fan 330 has only an axial
component to its velocity. Moreover, in at least one embodiment,
assembly 300 does not include fan 330. In at least one of these
embodiments, stator 380 reduces (or preferably eliminates) swirl
resulting from fan 320. As stated earlier, one advantage of the
above described configurations is the increase in pressure
resulting from the conversion of the kinetic energy associated with
swirl into potential energy.
[0049] In at least one embodiment, fan assembly 300 does not
include a stator. FIG. 6 depicts such an embodiment. In the
embodiment of FIG. 6, fan assembly 300 includes first motor
assembly 610. Coupled to first motor assembly 610 in the embodiment
of FIG. 6 is first impeller 625, which itself includes first hub
630 and one or more blades integrated therewith or attached thereto
(represented by blades 635-1 and 635-n in FIG. 6). In the
embodiment of FIG. 6, first motor assembly 610, and therefore,
first impeller 625 coupled thereto, are coupled to strut assembly
620. In the embodiment of FIG. 6, strut assembly 620 includes
struts 675. Struts 675 support a central location 670 to which
motor assembly 610 and impeller 625 are mounted. Also mounted to
central location 670 in the embodiment of FIG. 6 is second motor
assembly 615. Preferably, coupled to second motor assembly 615 is
second impeller 640, which itself includes second hub 645 and one
or more blades integrated therewith or attached thereto
(represented by blades 650-1 and 650-n) in FIG. 6. In the
embodiment of FIG. 6, this conglomeration of first motor assembly
610, first impeller 625, strut assembly 620, second motor assembly
615, and second impeller 640 is disposed within, and preferably
secured to, housing 650. Furthermore, in at least one embodiment,
attached to or integrated with housing 650 is first finger guard
660 and second finger guard 665.
[0050] In the embodiment of FIG. 6, in order to compensate for any
swirl resulting from first impeller 625, second impeller 640 may be
rotated in a direction opposite to that of first impeller 625.
Moreover, in such an embodiment, preferably, the dimensions and
orientations of blades 650-1 and 650-n mirror those of blades 635-1
and 635-n so that the airflow resulting, at least in part, from
second impeller 640 is in the same direction as the airflow
resulting, at least in part, from first impeller 625.
[0051] The embodiment of fan assembly 300 depicted in FIG. 6 may
have other configurations. For example, fan assembly 300 of FIG. 6
may include a fewer or greater number of components than that
depicted in FIG. 6, as well as one or more components other than
those depicted in FIG. 6. For instance, in at least one embodiment,
first motor assembly 610 and second motor assembly 615 are coupled
to different strut assemblies. Furthermore, in one embodiment,
first motor assembly 610 and second motor assembly 615 may share
electronics. Moreover, in one embodiment, first impeller 625 and
second impeller 640 share a motor assembly. In addition, housing
650 may further include stationary venturi (not shown) having an
inner surface that, in a known manner, typically resembles an
airfoil rotationally symmetric about hub 630 and/or hub 645, which
is closely spaced radially beyond the distal ends of rotating
blades 635-1 and 635-n and/or blades 650-1 and 650-n. Furthermore
blades 635-1 and 635-n and/or blades 650-1 and 650-n may include
winglets as discussed earlier with respect to U.S. patent
application Ser. No. 09/867,194. Furthermore, in at least one
embodiment, rather than the counter rotation described above, the
fan assembly of FIG. 6 may be configured such that first impeller
625 and second impeller 640 rotate in the same direction.
[0052] In at least one embodiment of fan assembly 300, integral
electronics of the fan assembly may be designed such that if either
first motor assembly 610 or second motor assembly 615 fails, the
remaining functioning motor assembly speeds up the rotation of the
impeller coupled thereto to compensate for the failed fan.
Moreover, in one embodiment, the rotation of first impeller 625 and
second impeller 640 is synchronized so to limit the number of
acoustic beat frequencies.
[0053] In addition, the embodiment of fan assembly 300 depicted in
FIG. 6 is not limited to configurations where no stators are
present. In at least one embodiment, a stator (e.g., stator 380) is
disposed between first impeller 625 and second impeller 640.
Moreover, in at least one embodiment a stator (e.g., stator 380) is
included as part of strut assembly 620 (e.g., part of struts 690
and/or central location 670). In at least one of these embodiments,
first impeller 625 and second impeller 640 may rotate in the same
direction. Moreover, in addition to or in lieu of a stator disposed
between first impeller 625 and second impeller 640, fan assembly
300 may include one or more stators at other locations. For
example, a stator may be attached to or integrated with first
finger guard 660 and/or second finger guard 665. Moreover, a
stator(s) not attached to, integrated with, or disposed within
housing 650 may be present in the fan assembly.
[0054] In at least one embodiment, the above described air moving
assemblies, or at least some of the components thereof, are
employed in cooling applications for electronic devices.
[0055] Various embodiments of the present invention overcome the
problems associated with the prior art. For instance, various
embodiments of the present invention are capable of counteracting
undesired swirl hampering the efficiency of prior art devices. In
at least one embodiment of the present invention, since undesired
swirl is counteracted, the desired pressure increase expected by
the prior art is achieved, and, in some embodiments, surpassed.
Morever, in at least one embodiment of the present invention, a
desired pressure increase is achieved through the intentional
impartation of what is considered in the art to be undesirable
swirl.
[0056] Furthermore, certain losses experienced in prior art
systems, such as expansion and contraction losses, are reduced (and
in some instances, eliminated) in various embodiments of the
present invention. In at least one embodiment, a stator has
sufficient dimensions to at least reduce one expansion and/or one
contraction between the stator and an air moving device. For
example, in at least one embodiment, the annular area of a surface
of the stator is the same as that of one or more of the other
components (e.g., air moving devices) of the assembly.
[0057] Likewise, in various embodiments, the stator of embodiments
the present invention may be inserted into or otherwise used with
known air moving devices and/or assemblies to increase the
performance of such devices and/or assemblies. For example, in one
embodiment, the stator may be inserted between two fans of an N+1
series configuration to increase the performance of the
configuration. As another example, in another embodiment, the
stator may be used to effectively convert a less expensive tube
axial fan into the relatively more expensive vane axial fan.
[0058] In addition, in at least one embodiment of the present
invention, valuable device space is saved by the sharing of
components between air moving devices (e.g., shared strut assembly,
shared motor assembly, shared electronics, and/or shared housing).
Therefore, cooling system designs and/or electronic device designs
need not be compromised so as to accommodate certain air moving
system configurations (e.g., N+1 configurations), as occurs in the
prior art.
[0059] In at least one embodiment, the air moving assembly of the
present invention helps compensate for the impedance resulting from
a non-functioning fan (i.e., the failed fan state) by increasing
the total pressure produced by embodiments of the fan assembly via
stators and/or counter rotating fans.
[0060] In addition, in at least one embodiment, the rotation of the
fans is synchronized so as to limit the number of acoustic beat
frequencies.
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