U.S. patent application number 11/401769 was filed with the patent office on 2007-10-11 for rotary fan with encapsulated motor assembly.
Invention is credited to David J. Allen, Mark S. Bader, Jeremy S. Carlson, Nicholas T. Pipkorn, Todd R. Stephens, Michael D. Turner.
Application Number | 20070237656 11/401769 |
Document ID | / |
Family ID | 38575493 |
Filed Date | 2007-10-11 |
United States Patent
Application |
20070237656 |
Kind Code |
A1 |
Pipkorn; Nicholas T. ; et
al. |
October 11, 2007 |
Rotary fan with encapsulated motor assembly
Abstract
A fan assembly, such as a rotary axial fan assembly, is
disclosed with a shroud that is adapted to be mounted proximate to
a heat exchanger. The shroud is sized for conveying a flow of fluid
through the heat exchanger and the shroud. A stator fan blade
extends inward from the shroud for supporting a hub generally
central within the shroud. A motor stator is encapsulated within
the hub for receiving a fan rotor and fan blades for forcing the
flow of fluid through the heat exchanger and the shroud. The hub
may be formed from a thermally conductive material for transferring
heat from the motor stator into the flow of fluid for dissipating
the heat.
Inventors: |
Pipkorn; Nicholas T.;
(Gladstone, MI) ; Stephens; Todd R.; (Marquette,
MI) ; Carlson; Jeremy S.; (Gladstone, MI) ;
Allen; David J.; (Gladstone, MI) ; Bader; Mark
S.; (Gladstone, MI) ; Turner; Michael D.;
(Plymouth, MI) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Family ID: |
38575493 |
Appl. No.: |
11/401769 |
Filed: |
April 11, 2006 |
Current U.S.
Class: |
417/366 |
Current CPC
Class: |
F04D 29/526 20130101;
F04D 29/542 20130101 |
Class at
Publication: |
417/366 |
International
Class: |
F04B 39/06 20060101
F04B039/06 |
Claims
1. A rotary axial fan assembly comprising: a shroud that is adapted
to be mounted proximate to a heat exchanger, the shroud being sized
for conveying a flow of fluid through the heat exchanger and the
shroud; at least one stator fan blade extending inward from the
shroud; a hub oriented generally centrally within the shroud,
supported by the at least one stator fan blade; and a motor stator
encapsulated within the hub, the motor stator being adapted for
receiving a fan rotor for supporting fan blades for forcing the
flow of fluid through the heat exchanger and the shroud such that
in operation of the fan assembly, heat generated by the motor
stator is transferred to the hub and into the flow of fluid for
dissipating heat into the flow of fluid.
2. The rotary axial fan assembly of claim 1 wherein the hub is
formed from a thermally conductive material for transferring heat
from the motor stator into the flow of fluid for dissipating the
heat into the flow of fluid.
3. The rotary axial fan assembly of claim 1 wherein the motor
stator further comprises a series of motor windings insert molded
into an end cap for contact with the hub for conducting heat from
the motor windings to the hub, and wherein the hub is formed from a
thermally conductive material for transferring heat from the motor
stator into the flow of fluid.
4. The rotary axial fan assembly of claim 1 wherein the motor
stator is press fit into the hub.
5. The rotary axial fan assembly of claim 1 wherein the motor
stator is at least partially press fit into the hub.
6. The rotary axial fan assembly of claim 1 wherein the hub is
formed from a material having a coefficient of thermal conductivity
within a range of 10 to 175 Watts per meter*Kelvin.
7. The rotary axial fan assembly of claim 1 wherein the hub is
formed from an aluminum material.
8. The rotary axial fan assembly of claim 1 wherein the hub and the
at least one stator fan blade are formed from a thermally
conductive material for transferring heat from the motor stator
into the flow of fluid.
9. The rotary axial fan assembly of claim 1 wherein the hub and the
at least one stator fan blade are formed unitarily from an aluminum
material.
10. The rotary axial fan assembly of claim 1 wherein the motor
stator further comprises wiring for powering the motor, wherein the
motor wiring is sealed within the hub by the encapsulation of the
motor stator.
11. The rotary axial fan assembly of claim 1 further comprising a
sealant for sealing the connection of the stator and the hub.
12. The rotary axial fan assembly of claim 1 wherein the stator is
in contact with the hub about the periphery of the stator for
uniform heat transfer from the motor stator to the hub.
13. The rotary axial fan assembly of claim 1 further comprising a
thermally conductive adhesive disposed at the connection of the
motor stator and the hub for enhancing heat transfer from the motor
stator to the hub.
14. The rotary axial fan assembly of claim 1 wherein the at least
one stator fan blade further comprises a plurality of radially
spaced apart stator fan blades.
15. The rotary axial fan assembly of claim 14 wherein the hub, the
shroud and the plurality of stator fan blades are cast unitarily
from an aluminum material.
16. The rotary axial fan assembly of claim 1 wherein the motor
stator further comprises a series of motor windings wound about
lamination plates and insert molded into an end cap for direct
contact of the lamination plates with the hub for conducting heat
from the motor windings to the hub, and wherein the hub is formed
from a thermally conductive material for transferring heat from the
motor stator into the flow of fluid.
17. The rotary axial fan assembly of claim 16 wherein the motor
stator is press fit into the hub.
18. The rotary axial fan assembly of claim 16 wherein the motor
stator is at least partially press fit into the hub.
19. A rotary axial fan assembly comprising: a shroud that is
adapted to be mounted proximate to a heat exchanger, the shroud
being sized for conveying a flow of fluid through the heat
exchanger and the shroud; a plurality of radially spaced apart
stator fan blades extending inward from the shroud; and a motor
stator oriented generally centrally within the shroud, supported by
the plurality of stator fan blades, the motor stator being adapted
for receiving a fan rotor and fan blades for forcing the flow of
fluid through the heat exchanger and the shroud; wherein the shroud
and the plurality of stator fan blades are formed unitarily from a
thermally conductive material for transferring heat from the motor
stator into the flow of fluid for dissipating the heat into the
flow of fluid.
20. A rotary axial fan assembly comprising: a shroud that is
adapted to be mounted proximate to a heat exchanger, the shroud
being sized for conveying a flow of fluid through the heat
exchanger and the shroud; a plurality of radially spaced apart
stator fan blades extending inward from the shroud; and a motor
stator oriented generally centrally within the shroud, supported by
the plurality of stator fan blades, the motor stator being adapted
for receiving a motor rotor and fan blades for forcing the flow of
fluid through the heat exchanger and the shroud; wherein the shroud
and the plurality of stator fan blades are formed unitarily from a
material having a coefficient of thermal conductivity within a
range of 10 to 175 Watts per meter*Kelvin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to heat transfer systems, more
particularly to fan assemblies utilized for moving a fluid in a
heat transfer system.
[0003] 2. Background Art
[0004] Motor vehicles commonly utilize heat exchangers to dissipate
heat collected in the operation of the motor vehicle to the ambient
air. These heat exchangers include radiators for cooling an
internal combustion engine, or a heater core for providing heat to
a passenger compartment for climate control.
[0005] Internal combustion engine cooling systems that utilize a
heat exchanger may also include a rotary axial fan for enhancing
the movement of air through the heat exchanger. For example, a
radiator in conventional motor vehicles includes a fan rearward or
forward of the radiator for forcing air through the radiator.
Typically, a shroud is provided to generally restrict the air to
flow axially through the radiator and the fan. The fan may be
driven directly from the operation of the internal combustion
engine by a belt or the like. Also, the fan may be driven by an
independent motor for rotating the fan and forcing the air through
the heat exchanger, as commonly utilized for transversely mounted
internal combustion engines. Air is commonly forced through a
conventional heater core through a fan which is operated by the
climate controls within the passenger compartment.
[0006] Fan assemblies often include a rotary axial fan that is
supported by a hub on the shroud. The hub is supported by an array
of stator fan blades extending inward from the shroud for
structurally supporting the rotary axial fan and for permitting air
to pass through the shroud. Often times, a motor may be mounted to
the hub and supported by the stator fan blades of the shroud, for
imparting rotation to the rotary axial fan.
SUMMARY OF THE INVENTION
[0007] An embodiment of the present invention provides a rotary
axial fan assembly with a shroud that is adapted to be mounted
proximate to a heat exchanger. The shroud is sized for conveying a
flow of fluid through the heat exchanger and the shroud. At least
one stator fan blade extends inward from the shroud. A hub is
oriented generally centrally within the shroud and is supported by
the stator fan blade. A motor stator is encapsulated within the
hub. The motor stator is adapted for receiving a fan rotor with fan
blades for forcing the flow of fluid to the heat exchanger and the
shroud.
[0008] Another embodiment of the present invention provides a hub
formed from a thermally conductive material for transferring heat
from the motor stator into the flow of fluid for dissipating the
heat into the flow of fluid.
[0009] A further embodiment of the present invention provides a hub
formed from a material having a coefficient of thermal conductivity
within a range of 10 to 175 Watts per meter*Kelvin.
[0010] Yet another embodiment of the present invention a shroud and
stator fan blades that are formed unitarily from a thermally
conductive material.
[0011] The above embodiments and other embodiments, aspects,
objects, features, and advantages of the present invention are
readily apparent from the following description of embodiments of
the invention when taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic illustration of an internal combustion
engine cooling system in accordance with the teachings of the
present invention;
[0013] FIG. 2 is a perspective view of a rotary axial fan assembly
in accordance with the present invention;
[0014] FIG. 3 is a cross-section view of the rotary axial fan
assembly of FIG. 2; and
[0015] FIG. 4 is an exploded perspective view of the rotary axial
fan assembly of FIG. 2.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0016] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention that
may be embodied in various and alternative forms. The figures are
not necessarily to scale; some features may be exaggerated or
minimized to show details of particular components. Therefore,
specific structural and functional details disclosed herein are not
to be interpreted as limiting, but merely as a representative basis
for the claims and/or as a representative basis for teaching one
skilled in the art to variously employ the present invention.
[0017] With reference now to FIG. 1, an internal combustion engine
cooling system is illustrated schematically and indicated generally
by reference numeral 10. The cooling system 10 includes a radiator
12 that receives heated coolant from the internal combustion engine
(not shown) and transfers heat from the coolant to air that passes
through the radiator 12. Air is passed through the radiator 12 by
movement of the vehicle and air is also forced by a rotary axial
fan 14. An external shroud 16 is provided to limit the movement of
air to travel in an axial direction. The shroud 16 may be mounted
to the radiator 12. The fan 14 is mounted to a drive member 18,
which may be driven by a motor 20. The motor 20 may be mounted to
the shroud 16 by stator fan blades 22. The motor 20 drives the
drive member 18 and fan 14 for forcing air through the radiator 12,
shroud 16 and fan 14, thereby cooling coolant that passes through
the radiator 12.
[0018] Alternatively, the heat transfer system 10 may include any
heat exchanger, such as a heater core which passes coolant
therethrough while air is forced by a fan 14 for passing heated air
into a passenger compartment of a vehicle, or any other heat
transfer mechanism.
[0019] With reference now to FIG. 2, a rotary axial fan assembly 24
is illustrated in accordance with the present invention. The fan
assembly 24 includes a rotary axial fan 26 and a stator fan 28. The
stator fan 28 may be fixed within the vehicle for supporting the
rotary axial fan 26. Although a rotary axial fan and radiator are
illustrated and described, the invention contemplates any heat
exchanger such as radiators, heater cores, evaporators, condensers
and the like.
[0020] The stator fan 28 of the present embodiment includes a
shroud 30, which is generally annular for limiting a direction of
air flow through the fan assembly 24 to a generally axial direction
L. The shroud 30 may be provided with a plurality of mounting
flanges 32 for mounting the fan assembly 24 proximate to a heat
exchanger, such as a radiator 12. The stator fan 28 may also
include a radial array of stator fan blades 34 converging centrally
inward to a hub 36. The hub 36 may be supported by the stator fan
blades 34. Likewise, the rotary axial fan 26 may be mounted to the
hub 36 for rotation of the fan 26 relative to the hub 36. The
rotary axial fan 26 may include a series of rotary fan blades 38
extending from a fan hub 40. The rotary fan blades 38 may be
inclined relative to the axial flow direction L at an attack angle,
which is angled (non-radial) relative to the fan hub 40 such that
rotation of the rotary axial fan 26 in a counter-clockwise
direction, as illustrated by the arcuate arrow R in FIG. 2, causes
a flow of air in the generally axial direction L through the shroud
30.
[0021] Although the fan assembly 24 is illustrated as a puller fan
assembly, wherein air is pulled through the radiator 12 and
subsequently through the fan assembly 24, the invention
contemplates that the rotary axial fan 26 may be rotated in a
clockwise direction such that air is forced in a reversed linear
direction relative to the arrow L depicted in FIG. 2 for pushing
air through the fan assembly 24 and subsequently through the
associated radiator 12. Such rotation may be controlled by
electronics or may be a function of the relationship of the rotary
axial fan blades 38 relative to the fan hub 40. Alternatively, the
rotary axial fan 26 may be detachable from the stator fan 28 for
being mounted in either a pusher or puller orientation.
[0022] The fan assembly 24 illustrated in FIG. 2 may be sized to
adequately cool a radiator of a predetermined diesel engine. Of
course, other types of engines, engine cooling systems, and heating
or cooling of other heat exchangers is contemplated by the present
invention. Likewise, any number of fan assemblies 24 may be
utilized in combination with a cooling system or heat exchanger for
providing the required volumetric rate of fluid flow for the design
criteria of a given system or heat exchanger.
[0023] For the embodiment of FIG. 2, the rotary axial fan 26 is
rotationally driven by a motor 42 that is mounted to the stator fan
hub 36. The rotary axial fan 26 is rotated relative to the stator
fan 28. The motor 42 illustrated in FIG. 2 may be, for example, a
brushless DC motor. Of course the invention contemplates
utilization of various motors, including a motor with brushes,
within the spirit and scope of the present invention. The motor 42
may be driven independent of the rotation of the engine of the
vehicle, so that energy may be conserved by driving the rotary
axial fan 26 when necessary, and by driving the rotary axial fan 26
at a desired speed. Various factors affect the rate of heat
transfer through a cooling system 10, including the heat of coolant
within the heat exchanger, or radiator 12, external temperatures,
wind speeds and directions, velocity of the vehicle, and the like.
Accordingly, the motor 42 may be controlled electronically to
rotate the rotary axial fan 26 when necessary, and at a speed to
provide the desired rate of heat transfer.
[0024] With reference now to FIGS. 3 and 4, the motor 42 is
illustrated in further detail in the section and exploded views of
the fan assembly 24. In order to cool the motor 42, heat generated
by the motor 42 may be transferred to the stator fan 28 for
dissipation into air forced through the shroud 30. For example,
heat generated by the motor 42 may be transferred to the hub 36,
and subsequently to the stator fan blades 34 for convecting the
heat to air passed through the shroud 30 about the stator fan
blades 34.
[0025] In order to facilitate heat transfer from the motor 42 to
the stator fan 28, a motor stator 44 of the motor 42 is
encapsulated within the hub 36 of the stator fan 28. The motor
stator 44 includes an end cap 46 with motor windings 47 that are
disposed about lamination plates 48. The motor windings 47 are the
primary source of heat and the lamination plates 48 may act as a
heat sink for transferring heat from the motor windings 47. The
lamination plates 48 are encapsulated within an inner diameter of
the hub 36 for direct contact with the hub 36 as illustrated in
FIG. 3. This direct contact between the motor stator 44 and the hub
36 permits heat generated by the motor 42 to be conducted directly
to the hub 36. The hub 36 may provide minimal clearance between the
hub 36 and the motor stator 44 for reducing vibration of the fan
assembly 24 and for maximizing contact for enhancing the conduction
of heat therebetween. Additionally, the motor stator 44 may be
press fit or partially press fit within the hub 36 for further
enhancing the contact and rate of heat transfer by an interference
connection. Thus, the hub 36 provides a heat sink for the motor 42
that is in direct contact with the lamination plates 48 of the
motor stator 44.
[0026] To further enhance the engagement between the motor stator
44 and the stator fan 28, a thermally conductive adhesive may be
placed within the inner diameter of the hub 36 for providing direct
contact therebetween. A room temperature vulcanizing (RTV) sealant
may also be provided between a flange 50 of the end cap 46 and the
hub 36 for sealing the motor 42 and preventing contaminants from
getting within the motor 42.
[0027] To further enhance heat transfer from the motor stator 44 to
the hub 36, the end cap 46 of the motor stator 44 may be insert
molded to the motor windings 47 and the lamination plates 48 by an
injection molding process thereby removing any air or space between
the windings 47 of the motor stator 44. The windings 47 may be over
molded by a material that functions as an electrical insulator
between the windings 47, but also functions as a thermal conductor,
such as a thermally conductive plastic. The insulator of the motor
windings 47 may be molded separately or integrally with the end cap
46. The end cap 46 may be provided by a thermally conductive
polymer, such as a polymer having a coefficient of thermal
conductivity of one to three watts per meter*Kelvin (W/m*K). Thus
the thermally conductive plastic ensures heat transfer from the
windings 47 directly to the hub 36 without air gaps between the
windings 47.
[0028] By utilizing the hub 36 of the stator fan 28 for partially
housing the motor 42, the stator fan 28 functions as a heat sink
for drawing heat from the motor 42. Accordingly, the shroud 30,
stator fan blade 34 and the hub 36 may be formed of a thermally
conductive material for transferring the heat from the motor 42
into the path of forced air. For example, the stator fan 28 may be
die cast from aluminum which has a coefficient of thermal
conductivity of approximately 110 W/m*K. Die cast aluminum provides
optimal heat transfer characteristics and also provides adequate
structural integrity for supporting the fan assembly 24 and
resisting vibrations imparted by the motor 42.
[0029] Alternatively, the stator fan 28 may be sand cast from
aluminum thereby having a coefficient of thermal conductivity of
approximately 150 W/m*K. Of course, the invention contemplates that
the stator fan 28 may be formed from any material having a suitable
coefficient of thermal conductivity for acting as a heat sink and
cooling the motor 42. Depending on the application of a particular
fan assembly, a hub having a coefficient of thermal conductivity
within the range of 10 to 175 W/m*K should be suitable for
providing a heat sink by the hub 36 and stator fan blade 34 for
cooling the motor 42. Other reasonably suitable conductive
materials that meet the design tradeoffs between conductivity and
structural integrity include wrought aluminum, which has a
coefficient of thermal conductivity of approximately 167 W/m*K;
steel, which has a coefficient of thermal conductivity of
approximately fifty W/m*K; and magnesium, which has a coefficient
of thermal conductivity of approximately sixty W/m*K.
[0030] The fan assembly 24 is further provided with a fan rotor 52
for driving the rotary axial fan 26. The fan rotor 52 includes a
unitary shaft 54 and bearing assembly 56. The bearing assembly 56
is mounted within the hub 36 for supporting the shaft 54 for
rotation relative to the hub 36. The bearing assembly 56 may be
press fit within the hub 36 for assembling the fan rotor 52 and for
sealing the hub 36. The bearing assembly 56 may be sized to
withstand some unbalance of the fan assembly 24 thereby minimizing
or eliminating a need to balance the fan assembly 24 and reducing
manufacturing steps and overall cost of the fan assembly 24.
Additionally, the bearing assembly 56 includes double-lipped seals
58 on each axial end of the bearing assembly 56 about the shaft 54
for preventing contaminates from getting within the motor 42. The
double-lipped seals 58 render the bearing assembly 56 submersible
such that the hub 36 may be exposed to various external
contaminates such as inclement weather.
[0031] The fan rotor 52 also includes a magnet 60 mounted to an end
of the motor shaft 54 centrally disposed within the motor stator
44. The motor stator 44 includes wiring 62, which may be sealed by
the encapsulation of the motor 42 so that no additional seal is
required. For example, the wiring 62 may be insert molded into the
end cap 46 of the motor 42. The wiring 62 conveys a current through
the windings 47 of the motor stator 44 for imparting an
electromagnetic field for rotating the magnet 60 and consequently
the shaft 54 within the bearing assembly 56 relative to the hub 36
of the stator fan 28.
[0032] The magnet 60 may be press fit upon the shaft 54 to provide
a reliable connection and ease in assembly of the fan rotor 52. By
pressing the magnet 60 flush with an end of the shaft 54 as
illustrated in FIG. 3, accurate axial location of the magnet 60 may
be provided for maximum efficiency of the motor 42. Although any
order of assembly steps is contemplated within the spirit and scope
of the present invention, the magnet 60 may be assembled to the
shaft 54 after the bearing assembly 56 has been assembled to the
hub 36 of the stator fan 28.
[0033] A series of mechanical fasteners 64 are provided for
fastening the flange 50 of the motor stator 44 to the hub 36 of the
shroud 30. The mechanical fasteners 64 may be used to secure the
motor stator 44 to the hub 36 and/or to resist vibration in the fan
assembly 24. The mechanical fasteners 64 may also be utilized for
sealing the flange 50 of the motor stator 44 against the hub 36 of
the stator fan 28. The fasteners 64 may be utilized in combination
with an adhesive or a thermally conductive glue, which may be
utilized to fill the cavity within the hub 36 and the motor stator
44 for improving vibration resistance and aid heat transfer between
the motor stator 44 and the hub 36. Depending on the particular
application, the fasteners 64 may be utilized alone or in
combination with the adhesive, or the fasteners 64 may be omitted
if the adhesive is adequate for securing and sealing the motor
stator 44 to the hub 36.
[0034] The rotary axial fan 26 is mounted to the distal end of the
shaft 54. The rotary axial fan 26 may be assembled to the shaft 54
by utilization of a hub plate 66, which is formed, for example,
from steel and may be press fit onto the motor shaft 54. The
interference fit of the hub plate 66 and the shaft 54 provides a
reliable connection that is easily assembled by pressing the hub
plate 66 upon the shaft 54. The hub plate 66 may be pressed flush
to the end of the shaft 54 to provide accurate axial rotation of
the rotary fan blades 38 for optimizing efficiency of the fan
assembly 24. Although any sequence of manufacturing operations may
be contemplated within the spirit and scope of the present
invention, the hub plate 66 may be assembled to the shaft 54 after
the magnet 60 has been assembled to the shaft 54. Subsequently, the
motor stator 44 may be assembled to the hub 36 of the stator fan
28, and the fan hub 40 may be fastened to the hub plate 66 by
mechanical fasteners 68 or any suitable connection. By providing
the hub plate 66 with a flat surface for receiving the fan hub 40
and with a reduced diameter pilot 70 that extends through the fan
hub 40, unbalance of the fan assembly 24 may be minimized.
[0035] The rotary fan 26 may be formed of any suitable material for
forcing air through the fan assembly 24. For example, the rotary
fan 26 may be formed of a polymeric material that is sufficient to
withstand the stresses associated with forcing air through the fan
assembly 24, but is sufficiently lightweight for maximizing the
efficiency of the motor 42. A retaining plate 72 can be utilized
between the fasteners 68 and the fan hub 40 for distributing the
load from the fasteners 68 to an expanded area upon the fan hub
40.
[0036] In summary, a fan assembly 24 is disclosed, which maximizes
efficiency of the fan assembly 24 by minimizing components of the
fan assembly 24 while maximizing heat transfer associated with the
fan assembly 24 and for cooling a motor 42 for the fan assembly 24
thereby providing a low cost and efficient cooling system.
[0037] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *