U.S. patent application number 12/867842 was filed with the patent office on 2010-12-30 for hybrid flow fan apparatus.
This patent application is currently assigned to HORTON, INC.. Invention is credited to Kevin M. Cahill, Hooshang Didandeh, Eugene Elvin Williams.
Application Number | 20100329871 12/867842 |
Document ID | / |
Family ID | 40986096 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100329871 |
Kind Code |
A1 |
Cahill; Kevin M. ; et
al. |
December 30, 2010 |
HYBRID FLOW FAN APPARATUS
Abstract
A fan assembly for directing fluid flow in a hybrid radial and
axial direction includes a backplate having an inner diameter
portion and a substantially frusto-conical outer diameter portion
positioned about a center axis (CL), a plurality of blades
extending from the backplate, and an annular fan shroud positioned
adjacent to the plurality of blades and configured for co-rotation
therewith. The backplate, the plurality of fan blades and the fan
shroud form a fan subassembly, and an overall depth of the fan
subassembly is approximately 20-35% of an overall fan subassembly
diameter (oD1).
Inventors: |
Cahill; Kevin M.; (Fishers,
IN) ; Didandeh; Hooshang; (Zionsville, IN) ;
Williams; Eugene Elvin; (Frankfort, IN) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
THE KINNEY & LANGE BUILDING, 312 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415-1002
US
|
Assignee: |
HORTON, INC.
Roseville
MN
|
Family ID: |
40986096 |
Appl. No.: |
12/867842 |
Filed: |
February 19, 2009 |
PCT Filed: |
February 19, 2009 |
PCT NO: |
PCT/US09/01047 |
371 Date: |
August 16, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61066692 |
Feb 22, 2008 |
|
|
|
Current U.S.
Class: |
416/187 ;
416/186R; 416/193R |
Current CPC
Class: |
F05D 2230/232 20130101;
F04D 29/281 20130101; F05D 2300/433 20130101; F04D 17/06 20130101;
F04D 29/023 20130101; F04D 29/626 20130101 |
Class at
Publication: |
416/187 ;
416/186.R; 416/193.R |
International
Class: |
F04D 29/38 20060101
F04D029/38; F04D 29/28 20060101 F04D029/28; F04D 29/44 20060101
F04D029/44 |
Claims
1. A fan assembly for directing fluid flow in a hybrid radial and
axial direction, the assembly comprising: a backplate having an
inner diameter portion and a substantially frusto-conical outer
diameter portion positioned about a center axis, wherein the
frusto-conical outer diameter portion extends to a circumference of
the backplate; a plurality of blades extending from the backplate;
and an annular fan shroud positioned adjacent to the plurality of
blades and configured for co-rotation therewith, wherein the
backplate, the plurality of fan blades and the fan shroud form a
fan subassembly, wherein an overall depth of the fan subassembly is
approximately 20-35% of an overall fan subassembly diameter.
2. The assembly of claim 1, wherein the overall depth of the fan
subassembly is approximately 25-33% of the overall fan subassembly
diameter.
3. The assembly of claim 2, wherein the overall depth of the fan
subassembly is greater than or equal to approximately 26% and less
than 30% of the overall fan subassembly diameter.
4. The assembly of claim 1, wherein a discharge angle defined by
the outer diameter portion of the backplate is oriented at
approximately 65-80.degree. with respect to the axis.
5-6. (canceled)
7. The assembly of claim 1, wherein an inside diameter of the fan
inlet is approximately 80-90% of an overall diameter of the fan
subassembly.
8-10. (canceled)
11. The assembly of claim 1, wherein an inlet angle of the each of
the plurality of blades is approximately 15-30.degree., and wherein
an exit angle of each of the plurality of blades is approximately
40-90.degree..
12-13. (canceled)
14. The assembly of claim 1, wherein a total blade length is
approximately 450-550% of an overall diameter of the fan
subassembly.
15. The assembly of claim 14, wherein the total blade length is
approximately 480-520% of the overall diameter of the fan
subassembly.
16. The assembly of claim 1, wherein an inside diameter of the
plurality of blades is approximately 50-75% of an overall diameter
of the fan subassembly.
17-18. (canceled)
19. The assembly of claim 1, wherein the plurality of blades are
equally spaced and attached to the outer diameter portion of the
backplate.
20-23. (canceled)
24. The assembly of claim 1, wherein the inner diameter portion of
the backplate is substantially planar.
25-26. (canceled)
27. The assembly of claim 26, wherein the inner diameter portion of
the backplate comprises a metallic material, and wherein the outer
diameter portion of the backplate comprises a polymer material
overmolded on the inner diameter portion.
28-29. (canceled)
30. The assembly of claim 1 and further comprising: an annular
inlet shroud positioned adjacent to the fan shroud, wherein the
inlet shroud is rotationally fixed, wherein the inlet shroud
comprises a wall that defines an inlet opening and an outlet
opening, wherein the inlet opening has a smaller diameter than the
outlet opening, and wherein the wall has an arcuate cross-sectional
shape.
31-32. (canceled)
33. The assembly of claim 1, wherein the inner diameter portion of
the backplate is axially positioned at approximately a center of
mass of the fan subassembly.
34. The assembly of claim 1, wherein the plurality of blades have a
configuration selected from the group consisting of: a forward
curved configuration, a backward curved configuration, and a
backward inclined configuration.
35-36. (canceled)
37. The assembly of claim 1, wherein a discharge angle defined by
the outer diameter portion of the backplate is oriented at
approximately 65-80.degree. with respect to the axis, wherein an
inside diameter of the fan inlet is approximately 80-90% of an
overall diameter of the fan subassembly, wherein an inlet angle of
the each of the plurality of blades is approximately 15-30.degree.,
wherein an exit angle of each of the plurality of blades is
approximately 40-90.degree., wherein a total blade length is
approximately 450-550% of the overall diameter of the fan
subassembly, and wherein an inside diameter of the plurality of
blades is approximately 50-75% of the overall diameter of the fan
subassembly.
38. The assembly of claim 1, wherein a tilt angle of the plurality
of blades is within a range of approximately 0-15.degree..
39. The assembly of claim 1, wherein a tilt angle of the plurality
of blades is within a range of approximately 3-10.degree..
40-41. (canceled)
42. The assembly of claim 1 and further comprising: an at least
partially axially extending annular rib positioned at the
substantially frusto-conical outer diameter portion of the
backplate, wherein the annular rib extends opposite the plurality
of blades and is radially aligned with the plurality of blades.
43. A fan assembly for directing fluid flow in a hybrid radial and
axial direction, the assembly comprising: a backplate having an
inner diameter portion and a substantially frusto-conical outer
diameter portion positioned about a center axis; a plurality of
blades extending from the backplate; and an annular fan shroud
positioned adjacent to the plurality of blades and configured for
co-rotation therewith, wherein the backplate, the plurality of fan
blades and the fan shroud form a fan subassembly, wherein the total
blade length is approximately 480-520% of the overall diameter of
the fan subassembly.
44. The assembly of claim 43, wherein an inside diameter of the
plurality of blades is approximately 50-75% of an overall diameter
of the fan subassembly.
45. (canceled)
46. A fan assembly for directing fluid flow in a hybrid radial and
axial direction, the assembly comprising: a backplate having an
inner diameter portion and a substantially frusto-conical outer
diameter portion positioned relative to an axis; a plurality of
blades extending from the substantially frusto-conical outer
diameter portion of the backplate; and an annular fan shroud
positioned adjacent to the plurality of blades and configured for
co-rotation therewith, wherein the backplate, the plurality of fan
blades and the fan shroud form a fan subassembly, wherein an inside
diameter of the plurality of blades is approximately 50-75% of an
overall diameter of the fan subassembly, and wherein the inside
diameter of the plurality of blades is located radially outward
from the inner diameter portion of the backplate.
47. The assembly of claim 46, wherein the total blade length is
approximately 480-520% of the overall diameter of the fan
subassembly.
48. The assembly of claim 46, wherein the overall depth of the fan
subassembly is approximately 20-35% of the overall fan subassembly
diameter.
49. A fan assembly for directing fluid flow in a hybrid radial and
axial direction, the assembly comprising: a backplate having an
inner diameter portion and a substantially frusto-conical outer
diameter portion positioned about a center axis; an annular fan
shroud; and a plurality of blades extending between the backplate
and the fan shroud, wherein the backplate, the plurality of fan
blades and the fan shroud form a fan subassembly, wherein an
overall depth of the fan subassembly is approximately 20-35% of an
overall fan subassembly diameter, wherein a discharge angle defined
by the outer diameter portion of the backplate is oriented at
approximately 65-80.degree. with respect to the axis, wherein an
inside diameter of the fan inlet is approximately 80-90% of an
overall diameter of the fan subassembly, wherein an inlet angle of
the each of the plurality of blades is approximately 15-30.degree.,
wherein an exit angle of each of the plurality of blades is
approximately 40-90.degree., wherein a total blade length is
approximately 450-550% of the overall diameter of the fan
subassembly, and wherein an inside diameter of the plurality of
blades is approximately 50-75% of the overall diameter of the fan
subassembly.
Description
BACKGROUND
[0001] The present invention relates to fans and fan assemblies
suitable for automotive applications.
[0002] Modern vehicles, such as medium- and heavy-duty diesel
trucks, can have relatively high cooling demands. For instance,
diesel engine emissions requirements mandated by European and North
American regulations have placed greatly increased demands upon
engine cooling systems. Not only is more airflow required to
provide adequate cooling and increased pressure required to
overcome the restriction of radiators and other heat exchangers,
but vehicle designs dictate and limit the size of cooling system
components. Such limitations are of particular concern when low
hood lines are desired with truck and construction equipment for
better driver visibility. Without being able to increase an exposed
surface area of radiators and other heat exchangers, they are often
made thicker. Thicker (i.e., deeper) radiators and other heat
exchangers reduce engine compartment space available for other
cooling system components, such as fans and fan clutches.
[0003] Automotive applications have traditionally employed axial
flow fans to provide cooling flows. Axial flow fans generally move
air in a direction parallel to an axis of rotation of the fan.
However, the combination of increased flow requirements and thicker
heat exchangers radically increases the restriction of cooling
systems, to the point where conventional axial flow fans are no
longer capable of providing an adequate flow of air. Even with fan
systems that can be enlarged, the relatively low efficiency of
conventional axial flow fans cause excessive power draws (e.g.,
greater than or equal to about 15% of engine power) that reduce
useable power from the engine. Moreover, axial flow fans may not
operate as quietly as desired for automotive applications, which
can be a concern for meeting noise regulations.
[0004] It is well-known that mixed flow fans (also known as hybrid
flow fans) and radial flow fans (also known as centrifugal fans)
have greater efficiencies and flow-pressure characteristics than
axial flow fans, but mixed flow and radial flow fans are difficult
to package in most vehicle engine compartments. Radial flow fans
typically require large scroll housings for best efficiency, and if
used without such housings have radial discharge velocities that
are not conducive to movement around vehicle engines. Although
mixed flow fans do not have those problems of radial flow fans,
they are typically thicker (i.e., deeper) in the axial direction
than can be used in under-hood applications. Furthermore, mixed
flow fans are deceptively complicated devices. While the general
idea of a mixed flow fan appears simple, the tremendous amount of
experimentation and design required to tailor them to meet the
requirements of particular applications has meant that they are
rarely used in practice.
SUMMARY
[0005] A fan assembly for directing fluid flow in a hybrid radial
and axial direction includes a backplate having an inner diameter
portion and a substantially frusto-conical outer diameter portion
positioned about a center axis, a plurality of blades extending
from the backplate, and an annular fan shroud positioned adjacent
to the plurality of blades and configured for co-rotation
therewith. The backplate, the plurality of fan blades and the fan
shroud form a fan subassembly, and an overall depth of the fan
subassembly is approximately 20-35% of an overall fan subassembly
diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view of one embodiment of a fan
apparatus of the present invention, viewed from the front.
[0007] FIG. 2 is a perspective view of the fan apparatus of FIG. 1,
viewed from the rear.
[0008] FIG. 3 is a front elevation view of the fan apparatus of
FIGS. 1 and 2.
[0009] FIG. 4 is a side elevation view of the fan apparatus of
FIGS. 1-3.
[0010] FIG. 5 is a rear elevation view of the fan apparatus of
FIGS. 1-4.
[0011] FIG. 6 is a cross-sectional view of a portion of a fan
assembly according to the present invention.
[0012] FIG. 7 is a cross-sectional view of a number of the fan
apparatuses of FIGS. 1-6 in a stack.
[0013] FIG. 8 is a perspective view of a portion of the fan
apparatus of FIGS. 1-6.
[0014] FIG. 9 is a schematic view of an alternative embodiment of a
fan apparatus according to the present invention, shown with a fan
shroud omitted.
[0015] FIG. 10 is a front elevation view of another alternative
embodiment of a fan apparatus according to the present invention,
shown with a fan shroud omitted.
[0016] FIG. 11 is a front elevation view of yet another alternative
embodiment of a fan apparatus according to the present invention,
shown with a fan shroud omitted.
[0017] FIG. 12 is a graph of performance data for select
alternative embodiments of the fan assembly.
[0018] While the above-identified drawing figures set forth several
embodiments of the invention, other embodiments are also
contemplated, as noted in the discussion. In all cases, this
disclosure presents the invention by way of representation and not
limitation. It should be understood that numerous other
modifications and embodiments can be devised by those skilled in
the art, which fall within the scope and spirit of the principles
of the invention. The figures may not be drawn to scale. Like
reference numbers have been used throughout the figures to denote
like parts.
DETAILED DESCRIPTION
[0019] The present invention claims priority to U.S. Provisional
Patent Application No. 61/066,692 entitled "High Efficiency Hybrid
Flow Fan," filed Feb. 22, 2008, which is hereby incorporated by
reference in its entirety.
[0020] In general, the present invention provides a quasi-mixed (or
hybrid) flow fan (generally referred to herein simply as a hybrid
flow fan), enabling the generation of fluid flow in a hybrid radial
and axial direction (i.e., somewhere in between 0 and 90.degree.
with respect to the axial direction) in response to rotational
input. In one embodiment, the fan has an overall depth (i.e.
thickness or width) of approximately 20-35% of an overall fan
diameter. The fan of the present invention can be used in engine
cooling systems, preferably when operating in a range of fan
throttling coefficients from approximately 0.04 to 0.08, where
throttling coefficient is defined as a ratio of velocity pressure
to total pressure, with the velocity pressure calculation based on
a superficial velocity equal to airflow divided by an axial
projected area of the fan.
[0021] The fan of the present invention provides numerous
advantages and benefits. For example, the fan provides a relatively
high airflow and relatively high pressure fan for engine cooling.
However, configuration of the fan is generally subject to several
constraints for use with automotive and other engine cooling
applications. The fan should preferably be mounted on the front of
an engine in the same manner as existing axial flow fans (e.g.,
belt-driven or crankshaft mounted). Further, the fan should allow
use of a viscous fan clutch (also called a viscous fan drive), a
device that allows speed control of the fan and helps isolate the
fan from crankshaft torsional vibration. An overall diameter of the
fan should preferably be comparable to existing axial flow fans. A
thickness (i.e., axial depth) of the fan should ideally be
comparable to existing axial flow fans, or as thin (i.e., axially
narrow) as possible because additional engine compartment space is
often difficult or impossible to allocate. An inlet diameter of the
fan should preferably be as large as possible to prevent high
high-velocity airflows in the center of radiators or other heat
exchangers that can result in detrimental airflow stratification
through radiator and heat exchanger cores. Airflow discharge from
the fan should preferably have an axial component to help guide the
air around sides of and past the engine. Static efficiency of the
fan should be as high as possible, and preferably greater than 50%,
to maximize the engine power available for useful work. Noise
produced by the fan should be as low as possible, and preferably no
louder than that of existing axial-flow fans operating with lesser
aerodynamic performance. Also, an interface (i.e., shrouding)
between an inlet to the fan and the radiator or other heat
exchangers should accommodate relative motion between the two
caused by engine rocking and frame twisting, yet be made of
structures achievable by ordinary assembly-line procedures.
[0022] Several of the constraints discussed above appear mutually
exclusive. The inlet diameter of the fan is one such example.
Generally, in a radial flow (or centrifugal) fan, greater pressure
production is achieved by decreasing a ratio of blade inside
diameter to blade outside diameter, thus making fan blades longer
in a radial direction. Doing so, however, decreases an axial inlet
area of the fan, increasing inlet velocity. Because spacing between
a vehicle radiator (or other heat exchanger) and fan is typically
short, such high velocity fluid flow directly in front of the fan
would likely create undesirable "dead zones" in corners of the
radiator (or other heat exchanger), thereby decreasing overall heat
exchange efficiency. Similarly, high airflow in a radial flow (or
centrifugal) fan is typically achieved by increasing the fan's
axial depth, an option not available for under-hood engine cooling
applications. It was necessary, therefore, in designing the fan of
the present invention to create a fan with design parameters that
produced a suitably efficient fan under a host of constraints. In
general, the fan of the present invention tends to exhibit
relatively high airflow and static efficiency characteristics while
still satisfying the constraints discussed above.
[0023] FIGS. 1-5 illustrate various views of one embodiment of a
fan apparatus 20. FIG. 1 is a perspective view of the fan apparatus
20, viewed from the front, and FIG. 2 is a perspective view of the
fan apparatus 20, viewed from the rear. FIGS. 3-5 are front, side
and rear elevation views, respectively, of the fan apparatus 20. As
shown in FIGS. 1-5, the fan apparatus 20 includes a backplate 22, a
plurality of blades 24 (also called airfoils), and a fan shroud 26
arranged for rotation about a centerline C.sub.L. The backplate 22,
the blades 24 and the fan shroud 26 are collectively referred to as
the fan subassembly. As shown by arrow 28 in FIG. 3, the
illustrated fan apparatus 20 is configured to rotate in a clockwise
direction, though it should be understood that the fan apparatus 20
can be configured to rotate in a counterclockwise direction in
alternative embodiments.
[0024] Those of ordinary skill in the art will appreciate that in
one embodiment the fan apparatus 20 is attached to a suitable
clutch (not shown), such as a viscous clutch of the type disclosed
in PCT Published Application No. WO 2007/016497 A1, and in turn
operatively connected to an engine (not shown). The clutch is
typically removably secured to the backplate 22 of the fan
apparatus 20 with bolts or other suitable attachment means. The
engine and clutch can selectively rotate the fan apparatus 20 at a
desired speed, with the fan apparatus 20 moving air to help cool
the engine. In a typical application, the fan apparatus 20 is
positioned between a radiator and/or other heat exchangers (not
shown) and the engine, with fan operation both directing cooling
air to the engine and moving air through the radiator (and/or other
heat exchangers) to further provide cooling.
[0025] FIG. 6 is a cross-sectional view of a portion of a fan
assembly 30 that includes the fan apparatus 20 and an inlet shroud
32. For simplicity, only one of the blades 24 of the fan assembly
30 is illustrated in FIG. 6. Fluid flow generated by the fan
assembly 30 during operation is illustrated by arrow 33, which
exits the fan apparatus 20 in a hybrid radial and axial direction
(i.e., in between 0 and 90.degree. with respect to the centerline
C.sub.L). It should be noted that airflow generated by the fan
apparatus 20 in a hybrid radial and axial direction is particularly
beneficial for under-hood automotive applications. Such a hybrid
airflow orientation is often more desirable than purely axial or
radial airflows for under-hood cooling applications, because it
tends to direct airflow around and past the engine for better
cooling.
[0026] The backplate 22 includes a substantially planar inner
diameter (ID) portion 34 (also called a hub) and a frusto-conical
outer diameter (OD) portion 36. The ID portion 34 is arranged
generally perpendicular to the centerline C.sub.L of the fan
apparatus 20. A metallic disk 38 (e.g., made of steel, aluminum,
etc.) is optionally incorporated into the ID portion 34 at the
centerline C.sub.L to provide a relatively rigid structure for
attachment of the fan apparatus 20 to a clutch or other rotational
input source (not shown). One or more openings are optionally
provided in the metallic disk 38 in the ID portion 34 at or near
the centerline C.sub.L to facilitate attachment to the clutch or
other rotational input source. The ID portion 34 is sufficiently
large to accommodate attachment to a clutch. Prior art mixed flow
fans tend to have an ID portion that is too small for mounting to a
conventional automotive fan clutch. The OD portion 36 is positioned
directly adjacent to and radially outward from the ID portion 34.
The OD portion 36 is arranged at an angle .theta..sub.1 with
respect to the centerline C.sub.L. Generally, a discharge angle of
the airflow 33 exiting the fan apparatus 20 is equal to the angle
.theta..sub.1. In the illustrated embodiment, the OD portion 36
extends to a perimeter (i.e., circumference) of the fan assembly
20. The backplate 22 has a radius R.sub.1, which defines a
corresponding overall diameter oD1. For common applications, values
of the diameter oD1 range from about 450 mm to about 750 mm, though
it will be appreciated that the diameter oD1 can have essentially
any value greater than zero as desired for particular
applications.
[0027] In the illustrated embodiment, a groove 39 is formed in the
rear side of the backplate 22 corresponding to and aligned with
each one of the blades 24. The grooves 39 help reduce thickness of
the backplate 22 and an overall mass of the fan apparatus 20. The
grooves 39 are optional, and generally are only present when the
backplate 22 and the blades 24 are integrally molded during
fabrication. When the backplate 22 is injection molded, the grooves
39 also help avoid sink marks, which are molding defects that occur
due to volume shrinkage during cooling. Fabrication of the fan
apparatus 20 is discussed further below.
[0028] An annular rib 40 extends generally axially from the
backplate 22 at a rear side of the backplate 22 opposite the blades
24 (see FIGS. 2, 5 and 6). In the illustrated embodiment, the
annular rib 40 extends generally axially from the OD portion 36 of
the backplate 22, at a location in between the perimeter of the
backplate 22 and the ID portion 34. Also, the annular rib 40 is
axially recessed relative to the perimeter of the backplate 22. A
suitable number of gussets 42 (e.g., eight) are provided between
the annular rib 40 and the backplate 22 to provide structural
support. In the illustrated embodiment, the gussets 42 are
circumferentially spaced from one another and located at an OD face
of the annular rib 40. Balancing weights (not shown) are optionally
attached to the annular rib 40 to help balance the fan apparatus 20
during operation. In one embodiment, balancing weights of a known
configuration are adhesively secured at an ID face of the annular
rib 40, such that the annular rib 40 helps to radially retain the
weights during fan operation. The annular rib 40 can further
provide increased stiffness to the fan apparatus 20.
[0029] FIG. 7 is a cross-sectional view of three fan apparatuses
20, 20' and 20'' in a stack. Any number of fan apparatuses 20, 20'
and 20'' can be stacked together in further embodiments. As shown
in FIG. 7, each of the fan apparatuses 20, 20' and 20'' has an
identical configuration and are designated with similar reference
numbers, though reference numbers for components of the fan
apparatus 20' carry a prime designation and reference numbers for
components of the fan apparatus 20'' carry a double prime
designation. When stacked, the fan shrouds 26' and 26'' of the fan
apparatuses 20' and 20'' extend into a pocket defined between the
ribs 40 and 40' and the OD portions 36 and 36' of the backplates 22
and 22' of the adjacent fan apparatus 20 or 20'. Moreover, the ribs
40 and 40' of the fan apparatuses 20 and 20' are positioned
radially inward from the fan shrouds 26' and 26'' of the adjacent
fan apparatus 20' or 20'', and the backplates 22 and 22' contact
the adjacent fans shroud 26' or 26''. In this way, the fan
apparatuses 20, 20' and 20'' can be relatively easily aligned in a
stack for storage or transport, and the stack is relatively compact
and stable enough to resist falling over. The stack can optionally
be placed in a suitable container (not shown) for storage or
transport.
[0030] Turning again to FIGS. 1-6, the fan shroud 26 is secured to
each of the blades 24 opposite the backplate 22, and rotates with
the fan apparatus 20 during operation. In the illustrated
embodiment, the fan shroud 26 has a generally annular shape, and is
at least partially curved in a toroidal, converging-diverging
configuration. An ID portion of the fan shroud 26 curves away from
the backplate 22. The fan shroud 26 is generally secured to OD
portions of the blades 24. As shown in FIG. 6, the fan shroud 26
defines a projected width PW.sub.s (measured between axially
forward and rear extents of the fan shroud 26) and an inlet radius
R.sub.2 (measured between the centerline C.sub.L and a radially
inward extent of the fan shroud 26), with the radius R.sub.2
defining a corresponding diameter oD2. In an exemplary embodiment,
the diameter oD2 is about 85% of the diameter oD1. In one
embodiment, the projected width PW.sub.s is about 12% of the
diameter oD1. An OD portion of the fan shroud 26 is oriented at an
angle .theta..sub.2 with respect to the centerline C.sub.L.
[0031] The blades 24 extend from the OD portion 36 of the backplate
22 to the fan shroud 26. In the illustrated embodiment, a total of
sixteen blades 24 are provided, though the number of blades 24 can
vary in alternative embodiments (e.g., a total of eighteen blades
24, etc.). Each blade 24 defines a leading edge 44, which is
oriented at an angle .theta..sub.3 relative to the OD portion 36 of
the backplate 22, and a trailing edge 46, which is arranged
substantially parallel to the centerline C.sub.L in the illustrated
embodiment. Those skilled in the art will appreciate that opposite
pressure and suction sides of the blades 24 extend between the
leading and trailing edges 44 and 46. In the illustrated embodiment
the leading edges 44 of the blades 24 are not attached to the fan
shroud 26. The leading edges 44 of the blades 24 collectively
define a radius R.sub.3 about the centerline C.sub.L, which
corresponds to a blade inner diameter oD.sub.3. Because the blades
24 extend along the frusto-conical OD portion 36 of the backplate
22, the radial locations of the leading edges 44 of the blades 24
affect the center of mass of the fan apparatus 22 in the axial
direction. It is generally desirable to locate the center of mass
at an axially middle location to better balance the fan apparatus
20 during operation, particularly with respect to bearings of a
clutch to which the fan apparatus 20 can be mounted. In some
embodiments, the ID portion 34 is substantially aligned with the
center of mass of the fan apparatus 20 (e.g., within approximately
+/-2% of the overall diameter oD1 relative to the center of mass in
the axial direction). Furthermore, each blade defines an inlet
angle .beta..sub.1 and an exit angle .beta..sub.E (see FIG. 3). The
inlet angle .beta..sub.1 for each blade 24 is defined between a
tangent line at the leading edge 44 and to a blade mean thickness
line at the leading edge 44. The exit angle .beta..sub.E is defined
between a tangent line located at the trailing edge 46 and a mean
thickness line of the blade 24 at the trailing edge 46. Each blade
24 is oriented at a tilt angle .alpha..sub.T with respect to a line
normal to the OD portion 36 of the backplate 22 (i.e., a line
parallel to the centerline C.sub.L) (see FIG. 4). The blades 24 are
tilted in a direction into the direction of rotation of the fan
apparatus 20 designated by the arrow 28 in FIG. 3. It should be
noted that the blades 24 can be essentially axially oriented with
the tilt angle .alpha..sub.T equal to zero in some embodiments.
[0032] The blades 24 in the embodiment of the fan apparatus 20
shown in FIGS. 1-6 are configured in a backward inclined
arrangement. Those skilled in the art will recognize that as a
function of the relationship between the inlet angle .beta..sub.1
and the exit angle .beta..sub.E, fan blades can be configured in
backward curved, backward inclined, radial (or quasi-radial) tip,
forward curved, and radial blade arrangements. In various
alternative embodiments, any desired configuration of the blades is
utilized (see, e.g., FIGS. 9 and 10). Moreover, if the intended
direction of rotation designated by the arrow 28 were to change
(i.e., from clockwise to counterclockwise), the arrangement of the
blades 24 for a particular configuration would be reversed (i.e.,
as a mirror image).
[0033] As shown in FIG. 6, a meridional streamline 48 is projected
on the illustrated blade 24. The meridional streamline 48 is
defined by a center or midpoint of a volume of fluid between the
backplate 22 and the fan shroud 26 between two adjacent blades 24
from an inlet at the leading edge 44 of the blades 24 to an outlet
at the trailing edge 46 of the blades 24. The meridional streamline
48 is generally a curve or arc that relates to the fluid flow
illustrated by the arrow 33. Each of the blades 24 has a meridional
length defined along its respective projected meridional streamline
48. A total blade length L.sub.Btot is defined as the cumulative
length obtained by adding together the meridional lengths of each
of the blades 24 of the fan apparatus 20. The total blade length
L.sub.Btot is affected by the number of blades 24 that the fan
apparatus 20 includes, as well as by dimensions of the individual
blades 24.
[0034] The fan apparatus 20 defines a projected width PW.sub.f
(i.e., an overall depth or thickness) in the axial direction. In
the illustrated embodiment, the projected width PW.sub.f is defined
between the axially forward extent of the fan shroud 26 and an
axially rear extent of the OD portion 36 of the backplate 22. In
one embodiment, the overall diameter oD1 of the fan apparatus 20 is
approximately 550 mm and the projected with PW.sub.f of the fan
apparatus 20 is approximately 165 mm. While the fan apparatus 20 is
generally thicker (i.e., deeper in the axial direction) than a
conventional axial flow fan, the fan apparatus 20 can have a
thickness of only about 180-200% relative to the thickness of a
conventional axial flow fan compared to about 250% for prior art
mixed flow fans and about 300% for prior art radial flow fans.
[0035] The inlet shroud 32 is an annular member positioned adjacent
to the fan apparatus 20, and includes an ID portion 50 that is at
least partially curved in a toroidal configuration. The inlet
shroud 32 defines an upstream opening that is larger than a
downstream opening. Typically, the inlet shroud 32 is rotationally
fixed, and in under-hood applications can be secured to an engine,
a radiator or other heat exchanger, a vehicle frame, etc. The inlet
shroud defines a radius R.sub.4 at a radially inward extent of the
ID portion 50, with the radius R.sub.4 corresponding to a diameter
oD.sub.4. In the illustrated embodiment, at least part of the ID
portion 50 of the inlet shroud 32 is positioned within an upstream
portion of the fan shroud 26, and extends rearward of the axially
forward extent of the fan shroud 26. In other words, an axial
overlap is formed between the fan shroud 26 and the inlet shroud
32. A generally radial gap is present between the fan shroud 26 and
the inlet shroud 32, which, in under-hood applications, allows for
relative movement between those components due to engine rocking,
frame twisting, vibration or other movements. During operation,
fluid flow in the direction of the arrow 33 passes through a
central opening of the inlet shroud 32 to the fan apparatus 20. The
inlet shroud 32 can help guide airflow to the fan apparatus 20 from
a radiator or other heat exchanger. Also, some additional fluid
flow may reach the fan apparatus 20 through the generally radial
gap between the fan shroud 26 and the inlet shroud 32.
[0036] The configuration of the fan apparatus 20 according to the
present invention can vary as desired for particular applications.
Table 1 provides three possible ranges for parameters of the fan
apparatus 20. The values given in Table 1 are all approximate. It
should also be noted that the values in Table 1 are provided merely
by way of example and not limitation. Moreover, Table 1 should be
interpreted to allow independent selection of individual
parameters. For instance, one parameter can be selected from the
"first range" column while another parameter can be selected from
the "second range" column, and so forth.
TABLE-US-00001 TABLE 1 Parameter First Range Second Range Third
Range OD1 up to .infin. 680 mm 550 mm (equal to twice R.sub.1)
OD2(equal to 80-90% of OD1 82-88% of OD1 84-86% of OD1 twice
R.sub.2) OD3(equal to twice R.sub.3) 50-75% of OD1 55-70% of OD1
58-65% of OD1 OD4 <OD2 OD2 - x, where x is (equal to twice
R.sub.4) about 12-24 mm .theta..sub.1 65-80.degree. 67-75.degree.
68-70.5.degree. .theta..sub.2 50-80.degree. 60-70.degree.
.theta..sub.3 90.degree. .beta..sub.I 15-30.degree. 18-28.degree.
20-25.degree. .beta..sub.E 40-90.degree. 50-80.degree.
55-70.degree. .alpha..sub.T 0-15.degree. 3-10.degree. 4-6.degree.
PW.sub.f 20-35% of OD1 25-35% of OD1 28-32% of OD1 PW.sub.s 10-15%
of OD1 12-13% of OD1 L.sub.Btot 450-550% of OD1 450-550% of OD1
480-520% of OD1
[0037] FIG. 8 is a perspective view of a portion of the fan
apparatus 20. As shown in FIG. 8, an optional fillet 52 is located
between the blade 24 and the fan shroud 26. The blade 24 has an
unattached tip portion 54 adjacent to the leading edge 44. In the
illustrated embodiment, the fillet 52 is integrally formed with the
blade 24, and extends in a generally chordwise direction from the
unattached tip portion 54 of the blade 24 to the fan shroud 26,
facing generally radially inward. The fillet 52 physically contacts
the fan shroud 26, and can optionally be joined to the fan shroud
26. The fillet 52 is optionally provided on each of the blades of
the fan apparatus 20, and can be omitted entirely in alternative
embodiments. The presence of the fillet 52 helps to reduces
stresses at the interface between each blade 24 and the fan shroud
26.
[0038] The fan assembly 30, including the fan apparatus 20, can be
manufactured in a variety of ways. Typically components of the fan
assembly 30 are made of a polymer or other injection-moldable
material, though fiberglass, metals and other suitable materials
can alternatively be used. In one embodiment, injection molding is
utilized, in which a polymer material, such as nylon, forms
essentially all of the components of the fan assembly 30, except
for the metallic disk 38, which can be made of steel. The blades 24
and the backplate 22 are usually integrally formed as a single
subassembly. If the blades 24 and backplate 22 are injection
molded, the metallic disk 38 can be overmolded with the polymer
material to integrally form the blades 24 and the backplate 22. The
fan shroud 26 and the inlet shroud 32 are generally each separately
formed by injection molding or other suitable techniques. The fan
shroud 26 is then attached to the blades 24 of the subassembly,
using a welding process, mechanical fasteners or other suitable
techniques. A welding or welding-like process, such as ultrasonic
welding or high frequency electromagnetic welding and bonding, is
preferred. A configuration with welded joints between the blades 24
and the fan shroud 26 produces relatively low stresses on the weld
joints between the blades 24 and the fan shroud 26, while
simplifying the process of injection molding the individual parts
that are later welded together. The inlet shroud 32 is separately
attached to a mounting structure, and the fan apparatus 20 is
positioned adjacent to the inlet shroud 32 in a desired
installation location.
[0039] In other embodiments, the backplate 22, the blades 24 and
the fan shroud 26 of the fan apparatus 20 are integrally molded as
a single piece. While a single-piece construction offers strength
benefits, it tends to require complex and expensive dies to
achieve. Alternatively, the fan shroud 26 and the blades 24 are
integrally molded and attached to a separately molded backplate
22.
[0040] As previously mentioned, a fan apparatus according to the
present invention can have its blades arranged in a number of
different configurations in alternative embodiments, such as
backward curved, backward inclined, radial (or quasi-radial) tip,
forward curved, and radial blade configurations. Those terms are
derived from radial flow fan design. Different blade configurations
will have different operational effects, which are generally
interrelated to other fan apparatus parameters. The optimal blade
configuration will vary for different applications depending on the
desired performance characteristics and constraints on the design
of the fan apparatus. FIGS. 9 and 10 illustrate two additional
blade configurations, though it will be appreciated that others are
possible within the scope of the present invention.
[0041] FIG. 9 is a schematic view of an alternative embodiment of a
fan apparatus 120 that includes a backplate 122 and a plurality of
blades 124, and is configured to rotate in the direction of the
arrow 28 (i.e., clockwise). The fan apparatus 120 also includes a
fan shroud secured to the blades 124 that is omitted in FIG. 9 to
better reveal the blades 124. The general configuration and
operation of the fan apparatus 120 is similar to that of the fan
apparatus 20 described above. In the illustrated embodiment, the
blades 124 of the fan apparatus 120 are arranged in a forward
curved configuration.
[0042] FIG. 10 is a front elevation view of another alternative
embodiment of a fan apparatus 220 that includes a backplate 222 and
a plurality of blades 224, and is configured to rotate in the
direction of the arrow 28 (i.e., clockwise). The fan apparatus 220
also includes a fan shroud secured to the blades 224 that is
omitted in FIG. 10 to better reveal the blades 224. The general
configuration and operation of the fan apparatus 220 is similar to
that of the fan apparatus 20 described above. In the illustrated
embodiment, the blades 224 of the fan apparatus 220 are arranged in
a quasi-radial tip configuration. In a true radial tip
configuration, blades are curved such that their trailing edges are
arranged exactly radially. However, in the illustrated quasi-radial
tip configuration, the blades 224 are curved with trailing edges
246 of the blades 224 arranged close to radially, but not exactly
radially.
[0043] FIG. 11 is a front elevation view of yet another alternative
embodiment of a fan apparatus 320 that includes a backplate 322 and
a plurality of blades 324, and is configured to rotate in the
direction of the arrow 28 (i.e., clockwise). The fan apparatus 320
also includes a fan shroud secured to the blades 324 that is
omitted in FIG. 11 to better reveal the blades 324. The general
configuration and operation of the fan apparatus 320 is similar to
that of the fan apparatus 20 described above. In the illustrated
embodiment, the blades 324 of the fan apparatus 220 are arranged in
a backward curved configuration.
[0044] In view of the foregoing description, those skilled in the
art will recognize that a fan assembly according to the present
invention provides numerous advantages and benefits. For example, a
fan according to the present invention provides relatively high
pressure and airflow but is relatively thin and generally exhibits
a different aspect ratio than what a designer would otherwise
produce with the luxury of substantial axial depth space available.
Moreover, the fan of the present invention exhibits relatively good
operating static efficiency characteristics. The fan of the present
invention can also meet desired performance characteristics for
under-hood automotive cooling applications while simultaneously
satisfying the many design limitations associated with under-hood
applications.
[0045] In addition, a fan according to the present invention
provides relatively good noise characteristics, including both
noise intensity and noise quality characteristics. The fairest
comparison of noise between two fan types is when both are
operating at the same aerodynamic point (i.e. same flow and
pressure). Comparing a 680 mm diameter fan of the present invention
running 1900 RPM to a prior art 750 mm diameter axial flow fan
running at 1970 RPM, the fan of the present invention was 4 dBA
quieter. The fan of the present invention is quieter for two major
reasons. First, the fan of the present invention can develop a
desired level of static pressure at a slower rotational speed
compared to an axial flow fan, and fan noise is very strongly
dependent upon peripheral speed (i.e., tip speed). Second, flow of
air through passages of the fan of the present invention is much
smoother and much less turbulent than the flow of air through an
axial flow fan at the high pressures at which the fan of the
present invention is desired to operate. Typically, flow through an
axial flow fan under the conditions described above is known as
stalled flow, which is highly turbulent and unstable, and is
associated with a roaring noise.
[0046] Additional advantages and benefits not specifically
mentioned are also provided.
EXAMPLES
[0047] Prototype fan assemblies according to the present invention
were developed and tested, and computer simulations were run to
further explore fan assembly designs according to the present
invention. Prototype testing has shown that a fan according to the
present invention can achieve about 35% higher airflow, 15
percentage-points greater static efficiency and exhibit quieter
operating characteristics than state-of-the art axial flow fans,
while still being suitable for installation in under-hood
automotive cooling applications and exhibiting acceptable power
requirements.
[0048] A design of experiments (DOE) protocol was employed to run
simulations of a number of permutations of a number of judiciously
selected fan design variables. The DOE allows for optimization
while conducting tests on only a limited number of possible
permutations. Computational fluid dynamics (CFD) software (e.g.,
FLUENT.RTM. flow modeling software available from ANSYS, Inc.,
Santa Clara, Calif.) was utilized to generate simulation test data
according to each DOE. Multiple DOE studies were conducted. The
largest DOE conducted involved five factors with three possible
levels each, for a total of 243 (or 3.sup.5) possible combinations,
of which 27 variations were simulated in accordance with the
selections of factors and levels listed in Table 2.
TABLE-US-00002 TABLE 2 Factor Levels .beta..sub.I 20.degree. -
28.degree. - 33.degree. .beta..sub.E Backward Curved
(30-55.degree.) - Backward Inclined (55-65.degree.) - Forward
Curved (65-80.degree.) OD3 325 mm - 400 mm - 475 mm .theta..sub.1
60.degree. - 70.degree. - 80.degree. PW.sub.f 175 mm - 205 mm - 235
mm Tilt angle 0.degree. .theta..sub.3 90.degree. Number of Blades
16 OD1 680 mm Blade Thickness 3 mm
[0049] Results of the DOE were gathered for airflow rate (in kg/s),
static pressure (in Pa) and static efficiency (in %). FIG. 12 is a
graph of performance data for select alternative embodiments of the
fan assembly 20 according to the largest DOE. The graph of FIG. 12
denotes airflow (kg/s) along the horizontal axis vs. pressure (Pa)
along the left-hand vertical axis and static efficiency (%) along
the right-hand vertical axis. The 27 DOE results for static
efficiency vs. airflow are plotted in FIG. 12 with hollow squares,
and results for pressure vs. airflow are plotted in FIG. 12 with
solid diamonds. It should be noted that each hollow square is
vertically aligned with a corresponding solid diamond in FIG.
12.
[0050] The results for pressure vs. pressure vs. airflow data
points (solid diamonds) were specified to fall upon a quadratic
curve that approximates a typical engine cooling restriction curve.
The DOE results show that the corresponding static efficiency vs.
airflow data points (hollow squares) collectively define a boundary
curve 400. Based on the 27 DOE results, data points were
interpolated for three optimized designs of the fan apparatus 20.
For a design #1, performance was optimized for both best airflow
and best static efficiency, illustrated in FIG. 12 for static
efficiency as a hollow triangle and for pressure as a solid
triangle. For a design #2, performance was optimized for best
static efficiency, illustrated in FIG. 12 for static efficiency as
a hollow circle and for pressure as a solid circle. For a design
#3, performance was optimized from best airflow, illustrated in
FIG. 12 for static efficiency as a hollow hexagon and for pressure
as a solid hexagon. Parameters for the fan apparatus 20 associated
with designs #1-3 are provided in Table 3. Interaction between
parameters of the fan apparatus 20 is not intuitive and is
time-consuming to determine by physical prototype builds and
testing. Each of the designs #1-3 is feasible and may satisfy
different engine cooling applications with different
requirements.
TABLE-US-00003 TABLE 3 Parameter Design #1 Design #2 Design #3
.beta..sub.I 23.degree. 22.degree. 30.degree. .beta..sub.E
50.degree. (Backward 43.degree. (Backward 78.degree. (Forward
Curved) Curved) Curved) OD3 366 mm 413 mm 350 mm .theta..sub.1
75.degree. 73.degree. 78.degree. PW.sub.f 224 mm 219 mm 235 mm
[0051] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *