U.S. patent application number 09/933932 was filed with the patent office on 2002-02-21 for circumferential arc segment motor cooling fan.
This patent application is currently assigned to HORTON, INC.. Invention is credited to Nelson, Christopher A..
Application Number | 20020021973 09/933932 |
Document ID | / |
Family ID | 22848642 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020021973 |
Kind Code |
A1 |
Nelson, Christopher A. |
February 21, 2002 |
Circumferential arc segment motor cooling fan
Abstract
A cooling fan according to the present invention includes a
housing. A fan assembly includes a plurality of fan blades carrying
a rotor ring at the outer circumference of the fan assembly. A
plurality of stator elements are supported by the housing to
confront the rotor ring around only a portion of the outer
circumference of the fan assembly. A motor controller is
operatively connected to the stator elements to induce force on the
rotor ring to turn the fan assembly.
Inventors: |
Nelson, Christopher A.;
(Bloomington, MN) |
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: |
22848642 |
Appl. No.: |
09/933932 |
Filed: |
August 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60226366 |
Aug 18, 2000 |
|
|
|
Current U.S.
Class: |
417/355 ;
417/423.7 |
Current CPC
Class: |
H02K 41/03 20130101;
H02K 2201/15 20130101; H02K 7/14 20130101; F04D 25/066
20130101 |
Class at
Publication: |
417/355 ;
417/423.7 |
International
Class: |
F04B 035/04; F04B
035/00; F04B 017/00 |
Claims
1. A cooling fan system comprising: a first housing; a fan assembly
having an outer circumference and including a plurality of fan
blades and a rotor ring carried at the outer circumference of the
fan assembly; a first plurality of stator elements supported by the
first housing to confront the rotor ring around only a first
portion of the outer circumference of the fan assembly; and a motor
controller operatively connected to the first plurality of stator
elements to induce force on the rotor ring to turn the fan
assembly.
2. The cooling fan system of claim 1, wherein the rotor ring
includes a plurality of permanent magnets and the first plurality
of stator elements is configured as a brushless DC (BLDC)
motor.
3. The cooling fan system of claim 1, wherein the rotor ring
includes a plurality of metal laminations and the first plurality
of stator elements is configured as a switched reluctance motor
(SRM).
4. The cooling fan system of claim 1, further comprising: a second
housing; and a second plurality of stator elements supported by the
second housing to confront the rotor ring around only a second
portion of the outer circumference of the fan assembly, the second
plurality of stator elements being operatively connected to the
motor controller to induce force on the rotor ring to turn the fan
assembly.
5. The cooling fan system of claim 4, wherein the first and second
housings are arranged symmetrically around the rotor ring.
6. The cooling fan system of claim 4, further comprising: a third
housing; a fourth housing; a third plurality of stator elements
supported by the third housing to confront the rotor ring around
only a third portion of the outer circumference of the fan
assembly, the third plurality of stator elements being operatively
connected to the motor controller to induce force on the rotor ring
to turn the fan assembly; and a fourth plurality of stator elements
supported by the fourth housing to confront the rotor ring around
only a fourth portion of the outer circumference of the fan
assembly, the fourth plurality of stator elements being operatively
connected to the motor controller to induce force on the rotor ring
to turn the fan assembly.
7. The cooling fan system of claim 6, wherein the first, second,
third and fourth housings are arranged symmetrically around the
rotor ring.
8. A cooling fan system comprising: a first housing located in an
outer perimeter portion of the fan area; a fan assembly having an
outer circumference and comprising: a hub mounted on a journal; and
a plurality of fan blades supported by the hub, the fan blades
having a configuration selected based on a desired cooling
performance of the cooling fan system; a first plurality of stator
elements supported by the first housing around a first portion of
the outer circumference of the fan assembly; and a motor controller
operatively connected to the first plurality of stator elements to
induce force on the fan assembly to turn the fan assembly.
9. The cooling fan system of claim 8, wherein the fan assembly
includes a rotor ring carried by the fan blades at the outer
circumference of the fan assembly.
10. The cooling fan system of claim 9, wherein the rotor ring
includes a plurality of permanent magnets and the first plurality
of stator elements is configured as a brushless DC (BLDC)
motor.
11. The cooling fan system of claim 9, wherein the rotor ring
includes a plurality of metal laminations and the first plurality
of stator elements is configured as a switched reluctance motor
(SRM).
12. The cooling fan system of claim 8, further comprising: a second
housing located in the outer perimeter portion of the fan area; and
a second plurality of stator elements supported by the second
housing around a second portion of the outer circumference of the
fan assembly, the second plurality of stator elements being
operatively connected to the motor controller to induce force on
the fan assembly to turn the fan assembly.
13. The cooling fan system of claim 12, wherein the first and
second housings are arranged symmetrically around the fan
assembly.
14. The cooling fan system of claim 12, further comprising: a third
housing located in the outer perimeter portion of the fan area; a
fourth housing located in the outer perimeter portion of the fan
area; a third plurality of stator elements supported by the third
housing around a third portion of the outer circumference of the
fan assembly, the third plurality of stator elements being
operatively connected to the motor controller to induce force on
the fan assembly to turn the fan assembly; and a fourth plurality
of stator elements supported by the fourth housing around a fourth
portion of the outer circumference of the fan assembly, the fourth
plurality of stator elements being operatively connected to the
motor controller to induce force on the fan assembly to turn the
fan assembly.
15. The cooling fan system of claim 14, wherein the first, second,
third and fourth housings are arranged symmetrically around the fan
assembly.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of Provisional
Application No. 60/226,366 filed Aug. 18, 2000 for "Switched
Reluctance Motor (SRM)" by C. Nelson, B. Palmer, N. Mohan and A.
Jain.
INCORPORATION BY REFERENCE
[0002] The aforementioned Provisional Application No. 60/226,366 is
hereby incorporated by reference in its entirety. U.S. Application
No. 09/848,544 filed May 3, 2001 for "Brushless DC Ring Motor
Cooling System" by C. Nelson and B. Palmer is also hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a cooling fan, and more
particularly to a cooling fan having a circumferential arc segment
motor geometry.
[0004] Diesel power applications such as over-the-road trucks,
off-road equipment and agricultural equipment require a cooling
system to serve a variety of cooling needs in the equipment. These
systems typically contain a number of heat exchangers, a cooling
fan, and in some cases a fan drive. In cases where a fan drive is
not used, the fan is driven by a belt and continually rotates at a
fixed ratio to engine speed. At least three sub-systems are served
by the cooling fan, including the engine cooling system, the charge
air system and air conditioning system. Other systems such as a
transmission cooling system and hydraulic cooling system could also
be served by the cooling fan.
[0005] Typical fan drives are implemented as a clutch system of
some type, such as an on/off clutch, a viscous clutch, or a
hydraulic clutch. However, as noted in U.S. application Ser. No.
09/848,544 which has been incorporated herein by reference, clutch
driven cooling systems are not able to efficiently control the
power diverted to the fan based on the type of cooling requested. A
cooling system employing an electromagnetic fan motor for turning
the fan in direct relation to the type of cooling requested
provides a greater degree of efficiency.
[0006] Existing electromagnetic fan motor systems, such as might be
employed in a 12-volt automobile, are configured with the motor
located generally around the central axis of the fan, with fan
blades extending outward from a central hub around the motor toward
a peripheral fan shroud. While this arrangement is satisfactory for
many automotive cooling needs, there are some diesel applications
in which it would be beneficial to provide more torque for the
amount of power supplied and/or greater flexibility in the design
of the fan. These benefits could potentially be achieved with a
design that is somewhat similar in size and configuration to the
designs used by clutch driven fan systems, which have a simple hub
that selectively engages the spinning crankshaft and supports any
type of suitable fan design, selected based on the desired cooling
performance of the system. A novel electromagnetic cooling system
for achieving these benefits is the subject of the present
invention.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention is a circumferential arc segment motor
cooling fan that includes a fan assembly having a plurality of fan
blades carrying a rotor ring at the outer circumference of the fan
assembly. A plurality of stator elements are supported by a housing
to confront the rotor ring around only a portion of the outer
circumference of the fan assembly. A motor controller is
operatively connected to the stator elements to induce force on the
rotor ring to turn the fan assembly.
[0008] In some embodiments of the invention, a plurality of
housings may be provided to support stator elements confronting the
rotor ring around portions of the outer circumference of the fan
assembly. For example, configurations including two and four
housings may be employed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a front elevational view, with a portion shown in
section, of a circumferential arc segment motor cooling fan
according to a first embodiment of the present invention.
[0010] FIG. 2 is a side section view taken along the vertical axis
of the circumferential arc segment motor cooling fan of FIG. 1.
[0011] FIG. 3 is a section view illustrating the fan assembly of
the circumferential arc segment motor cooling fan in greater
detail.
[0012] FIG. 4 is a diagram illustrating the stator portion of the
circumferential arc segment motor cooling fan in greater
detail.
[0013] FIG. 5 is a front elevational view, with a portion shown in
section, of a circumferential arc segment motor cooling fan
according to a second embodiment of the present invention.
[0014] FIG. 6 is a front elevational view, with a portion shown in
section, of a circumferential arc segment motor cooling fan
according to a third embodiment of the present invention.
DETAILED DESCRIPTION
[0015] FIG. 1 is a front elevational view with a portion shown in
section, and FIG. 2 is a side section view taken along the vertical
axis, of circumferential arc segment motor (CASM) cooling fan 10
according to a first embodiment of the present invention. In the
embodiment shown in FIGS. 1 and 2, which utilizes a brushless DC
(BLDC) ring motor geometry, CASM cooling fan 10 includes fan
assembly 12 on bearing assembly 13a around journal 13b supported by
fan support 14, rotor ring 15 carried on the outer circumference of
fan assembly 12, permanent magnets 16 on rotor ring 15, and stator
housing 18 supporting stator laminations 20 to confront permanent
magnets 16. Windings 21 are wound around stator laminations 20 in a
three phase arrangement and connected by wiring to motor controller
22. CASM cooling fan 10 is situated in a radiator housing (not
shown) in an exemplary embodiment.
[0016] Fan assembly 12 essentially acts as the rotor of CASM
cooling fan 10 by carrying rotor ring 15 around its outer
circumference. In an exemplary embodiment, rotor ring 15 is molded
as part of the blades of fan assembly 12. Rotor ring 15 is
approximately as long as the pitch width of the fan blades, and is
blended into the end of each of the fan blades. Rotor ring 15
provides some airflow benefits by reducing the tip losses of fan
assembly 12, reducing fan noise, and allowing a shroud to be
designed in cooperation with rotor ring 15.
[0017] As explained above, windings 21 are wound around stator
laminations 20 and connected in a three phase arrangement in stator
housing 18. The amount of torque produced by CASM cooling fan 10 is
based on the number of interacting stator laminations 20 and rotor
permanent magnets 16 (as well as on the amount of power provided to
windings 21 by motor controller 22). Therefore, for a particular
spacing of stator laminations 20 and rotor permanent magnets 16,
the circumferential extent of stator housing 18 determines the
number of stator laminations 20 and therefore the number of
interacting stator laminations 20 and rotor permanent magnets 16.
The extent of stator housing 18 (and the number of stator
laminations 20) can therefore be selected based on the torque
required for the particular application of CASM cooling fan 10. In
the exemplary embodiment shown in FIGS. 1 and 2, stator housing 18
extends along only the lower portion of the outer circumference of
fan assembly 12 and rotor ring 15. This extent of stator housing 18
can provide sufficient torque for many applications because of the
relatively large diameter of the active portion of the motor.
[0018] FIG. 3 is a section view illustrating fan assembly 12 of the
circumferential arc segment motor cooling fan 10 in greater detail,
showing the relationship between the rotor and stator portions of
cooling fan 10. Fan assembly 12 carries rotor ring 15 around its
outer circumference. Rotor ring 15 carries back-iron 24 and
permanent magnets 16 facing outward to confront stator laminations
20 located around the outside of fan assembly 12. Stator housing 18
includes stator laminations 20 and windings 21 wound around stator
laminations 20, with potting compound 26 or another suitable
material filling the remainder of the cavity in stator housing 18
to secure stator laminations 20 and windings 21. In order to
operate the fan, a current is provided through windings 21 by motor
controller 22 (FIG. 1). The interaction between the current through
windings 21 and the magnetic field between stator laminations 20
and rotor permanent magnets 16 induces a force that causes fan
assembly 12 to turn.
[0019] FIG. 4 is a diagram with a portion cut away illustrating
stator housing 18 of circumferential arc segment motor cooling fan
10 in greater detail. As explained above, stator housing 18 has a
circumferential extent that may be selected according to the torque
requirements of the cooling system. Stator housing includes a
plurality of stator laminations 20 with windings 21 wrapped around
them in a three phase arrangement. The configuration of stator
housing 18 to fit in the circle-to-square interface portion of the
cooling fan makes efficient use of the space provided, while also
yielding excellent torque and overall fan performance.
[0020] FIG. 5 is a front elevational view, with portions shown in
section, of circumferential arc segment motor (CASM) cooling fan 30
according to a second embodiment of the present invention. CASM
cooling fan 30 is identical to CASM cooling fan 10 (FIGS. 1 and 2)
except that stator housing 38 is provided in the upper portion of
the assembly in addition to stator housing 18 provided in the lower
portion of the assembly. In an exemplary embodiment, stator
housings 18 and 38 are arranged symmetrically around rotor ring 15.
Stator housing 38 supports stator laminations 40 to confront
permanent magnets 16. Windings 41 are wound around stator
laminations 40 in a three phase arrangement and connected by wiring
to motor controller 22. In an exemplary embodiment, a single motor
controller 22 is employed to control the current delivered to
windings 21 and 41 in stator housings 18 and 38, respectively.
[0021] FIG. 6 is a front elevational view, with portions shown in
section, of circumferential arc segment motor (CASM) cooling fan 50
according to a third embodiment of the present invention. CASM
cooling fan 50 is identical to CASM cooling fans 10 (FIGS. 1 and 2)
except that stator housings 52, 54, 56 and 58 are provided in the
four corner portions of the assembly instead of stator housing 18
shown in FIG. 1. In an exemplary embodiment, stator housings 52,
54, 56 and 58 are arranged symmetrically around rotor ring 15.
Stator housings 52,54,56 and 58 are all configured in the same
manner, and include stator laminations 60 to confront permanent
magnets 16 carried by rotor ring 15. Windings 61 are wound around
stator laminations 60 in a three phase arrangement and connected by
wiring to motor controller 22. In an exemplary embodiment, a single
motor controller 22 is employed to control the current delivered to
windings 61 in stator housings 52, 54, 56 and 58.
[0022] It will be understood by those skilled in the art that
numerous numbers, positions and extents of stator housings may be
provided to achieve a desired amount of torque, up to the point
where the stator housing extends completely around the outer
circumference of fan assembly 12 and rotor ring 15. Typically, the
circumferential extent of the stator is substantially less than 360
degrees, due to the large diameter of rotor ring 15 confronted by
the laminations and windings of the stator.
Switched Reluctance Motor (SRM) Embodiment
[0023] In an alternative embodiment of the present invention,
described generally with respect to FIGS. 1 and 2, CASM cooling fan
10 may employ a SRM rather than a BLDC motor. The SRM turns fan
assembly 12 and rotor ring 15 by providing a magnetic attraction
between the electromagnetic teeth of the stator (stator laminations
20) and the steel teeth of the rotor (with the steel teeth
replacing permanent magnets 16). If one phase of the motor is
energized, the rotor teeth closest to the active stator teeth are
magnetically attracted. Just before the rotor teeth are aligned
with the active stator teeth, power is directed to the next phase.
This active phase in turn attracts its closest rotor teeth and so
on. In general, a switched, rotating group of magnetic fields
constantly attracts the rotor teeth causing the rotor to rotate
continuously.
[0024] Similar to the BLDC motor embodiment, SRM stator laminations
20 are located outside the outer diameter of rotor ring 15. The
stator does not form a complete circle around rotor ring 15, but
instead spans a particular circumferential arc segment defined by
the number of stator laminations 20 and active poles of rotor ring
15. The number of active rotor poles is dictated by the operating
specifications, which consist of torque, horsepower, speed, voltage
and current. The specified torque typically does not require 360
degrees of active poles due to the large diameter of rotor ring 15.
The stator arc can be located at any suitable location around the
rotor. The arc segment can also be split into multiple segments
located at advantageous locations around the rotor.
[0025] The SRM shares many of the benefits of a BLDC motor, as well
as other potential advantages. These advantages include the absence
of permanent magnets, reduction in assembly costs, simple salient
pole winding, stamped steel laminations for rotor ring 15 and
stator laminations 20, and the ability to run in very hot
environments due to the absence of permanent magnets.
[0026] The present invention, whether implemented as a BLDC motor,
a SRM or an alternative type of motor known in the art, has a
circumferential arc segment geometry that enables large amounts of
torque to be produced for a given diameter of the cooling fan. This
geometry also enables the cooling fan to employ any type of hub
supporting any type of suitable fan design selected based on the
desired cooling performance of the system, similar to the design of
a clutch driven cooling fan, due to the provision of the motor
around the outer circumference of the assembly that allows the
simple hub to be employed. Because of the relatively large diameter
of the confronting rotor ring 15 and stator laminations 20, the
stator needs only to extend only partially around the circumference
of the fan assembly, rather than completely around the fan
circumference. This geometry provides advantages in efficiency and
expense in some particular applications of the cooling system.
[0027] 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.
* * * * *