U.S. patent application number 11/646753 was filed with the patent office on 2008-07-03 for fan-motor assembly.
Invention is credited to David B. Finkenbinder, Harold A. Hughes.
Application Number | 20080159883 11/646753 |
Document ID | / |
Family ID | 39584235 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080159883 |
Kind Code |
A1 |
Finkenbinder; David B. ; et
al. |
July 3, 2008 |
Fan-motor assembly
Abstract
A fan assembly includes a base which couples to a motor
assembly. A shroud couples to the base and encloses a fan
therebetween. An airflow conduit is formed between the base and the
shroud and is positioned circumferentially around the fan. The
airflow conduit terminates at a horn and includes a cross-sectional
area which varies circumferentially. The airflow conduit includes a
width that varies circumferentially and is largest at the horn.
Inventors: |
Finkenbinder; David B.;
(Ravenna, OH) ; Hughes; Harold A.; (Akron,
OH) |
Correspondence
Address: |
RENNER KENNER GREIVE BOBAK TAYLOR & WEBER
FIRST NATIONAL TOWER FOURTH FLOOR, 106 S. MAIN STREET
AKRON
OH
44308
US
|
Family ID: |
39584235 |
Appl. No.: |
11/646753 |
Filed: |
December 28, 2006 |
Current U.S.
Class: |
417/360 |
Current CPC
Class: |
F04D 29/422 20130101;
F04D 29/4206 20130101 |
Class at
Publication: |
417/360 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Claims
1. A fan assembly, comprising: a base which couples to a motor
assembly; a shroud which couples to said base; at least one fan
enclosed between said base and said shroud; an airflow conduit
formed between said base and said shroud and positioned
circumferentially around said fan, said airflow conduit terminating
at a horn and including a cross-sectional area which varies
circumferentially; and wherein said airflow conduit includes a
width that varies circumferentially and is largest at said
horn.
2. The fan assembly according to claim 1, wherein said airflow
conduit includes a height that varies circumferentially and is
largest at said horn.
3. The fan assembly according to claim 1, wherein said shroud
includes a conduit wall and said base includes an inner wall, said
airflow conduit being formed between said conduit wall and said
inner wall, and wherein said conduit wall is curved in
cross-section.
4. The fan assembly according to claim 3, wherein said conduit wall
includes a constant cross-sectional radius.
5. The fan assembly according to claim 1, wherein said base
includes an outer flange forming at least part of said conduit,
said outer flange being curvilinear.
6. The fan assembly according to claim 1, wherein said base
includes an outer flange forming at least part of said conduit,
said outer flange including a radial distance from said fan that
varies circumferentially and is largest at said horn.
7. The fan assembly according to claim 6, wherein said base
includes a conduit wall that mates with said outer flange, said
conduit wall including a generally curved cross-sectional
shape.
8. The fan assembly according to claim 7, wherein said outer flange
includes a raised shoulder and said conduit wall includes a
circumferential groove, said raised shoulder is received in said
circumferential groove.
9. The fan assembly according to claim 3 wherein said inner wall is
substantially flat in cross-section.
10. The fan assembly according to claim 3 wherein said shroud
includes a port adapted to receive working air, said shroud further
including a cap extending radially outward from said port
terminating at said conduit wall, said cap being frustoconical.
11. The fan assembly according to claim 10 wherein said cap
includes a chamfer about a radial inner edge, said fan including a
ring that is at least partially received in said chamfer.
Description
TECHNICAL FIELD
[0001] The present invention is generally directed to motor
assemblies. In particular, the present invention is directed to a
shrouded tangential fan-motor assembly that increases motor
efficiency and air flow characteristics. Specifically, the present
invention is related to a shroud mountable to a fan end bracket
that forms a circumferentially non-uniform cross-sectional
area.
BACKGROUND ART
[0002] Vacuum motors employing a tangential bypass are used in many
applications such as vacuum manipulators, packaging equipment, bag
filling, cutting tables, appliances and exhaust air removal, to
name just a few. Such vacuum motor designs generally include a
cylindrical housing, or shroud, which encloses a motor-driven fan
rotating about an axis. Air is drawn into the housing via an
aperture at the top axial center of the housing above the fan. As
the fan rotates, the air is accelerated in the circumferential and
radially outward direction. The housing provides an outlet located
on the side of the fan opposed to the aperture. The outlet is a
generally cylindrical opening disposed tangentially on the radially
outer edge of the housing so that air traveling circumferentially
along the radial outer edge is expelled through the outlet in the
tangential direction. Such fans are efficient and have a small
profile which enables them to fit in apparatuses which require a
thin fan motor assembly.
[0003] As with most fan designs, efficiency is an important
concern. Current housing designs do not direct airflow in its most
efficient path within the housing. Specifically, unwanted
turbulence and dead zones are believed to be generated by the
uncontrolled path of the airflow from where the air is expelled
from the rotating fan to where the air exits the outlet. The fan
creates significant kinetic energy in the air by imparting
tangential speed. The air must be decelerated in a controlled
manner in order to convert the kinetic energy back to pressure.
Sudden changes in cross-section may cause eddies and turbulence
which dissipates the kinetic energy as heat instead of recovering
it as pressure. The total pressure (or vacuum) created by the
motor/fan assembly is thus negatively affected by allowing air to
exit the fan in an uncontrolled manner. Therefore, there is a need
to better manage air flow in order to achieve greater fan
efficiency. Further, there is a need to provide air flow management
features that are integral to the fan shroud and end bracket. This
allows cheaper production, faster assembly and greater
reliability.
[0004] Therefore, there exists a need in the art for a shroud and
end bracket assembly that directs airflow and increases
efficiency.
SUMMARY OF THE INVENTION
[0005] In view of the foregoing, it is a first aspect of the
present invention to provide a fan end bracket and shroud that
achieves improved efficiency.
[0006] Another aspect of the present invention is to provide a fan
assembly comprising a base which couples to a motor assembly, a
shroud which couples to the base, at least one fan rotated by the
motor assembly and enclosed between the base and the shroud, an
airflow conduit formed between the base and the shroud and
positioned circumferentially around the fan, the airflow conduit
terminating at a horn and including a cross-sectional area which
varies circumferentially, and wherein the airflow conduit includes
a width that varies circumferentially and is largest at the
horn.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a complete understanding of the objects, techniques and
structure of the invention, reference should be made to the
following detailed description and accompanying drawings,
wherein:
[0008] FIG. 1 is perspective view of a fan/motor assembly made in
accordance with the concepts of the present invention;
[0009] FIG. 2 is a top elevated view of the fan/motor assembly;
[0010] FIG. 3 is a partial cross-sectional view of the fan/motor
assembly;
[0011] FIG. 4 is a perspective view of the fan assembly;
[0012] FIG. 5 is an alternate perspective view of the fan
assembly;
[0013] FIG. 6 is a top view of the fan assembly;
[0014] FIG. 7 is a bottom view of the fan assembly;
[0015] FIG. 8 is a top view of a shroud used with the fan/motor
assembly according to the present invention;
[0016] FIG. 9 is a top view of an end bracket used with the
fan/motor assembly according to the present invention;
[0017] FIG. 10 is an exploded view of the fan assembly;
[0018] FIG. 11 is an alternate exploded view of the fan
assembly;
[0019] FIG. 12 is a side view of the fan assembly;
[0020] FIG. 13 is a sectional view of the fan assembly along lines
13-13 of FIG. 7;
[0021] FIG. 14 is a top view of the motor/fan assembly;
[0022] FIG. 14A is a sectional view of the fan assembly along lines
14A-14A of FIG. 14;
[0023] FIG. 14B is a sectional view of the fan assembly along lines
14B-14B of FIG. 14;
[0024] FIG. 14C is a sectional view of the fan assembly along lines
14C-14C of FIG. 14;
[0025] FIG. 14D is a sectional view of the fan assembly along lines
14D-14D of FIG. 14;
[0026] FIG. 14E is a sectional view of the fan assembly along lines
14E-14E of FIG. 14;
[0027] FIG. 14F is a sectional view of the fan assembly along lines
14F-14F of FIG. 14;
[0028] FIG. 14G is a sectional view of the fan assembly along lines
14G-14G of FIG. 14;
[0029] FIG. 14H is a sectional view of the fan assembly along lines
14H-14H of FIG. 14;
[0030] FIG. 14J is a sectional view of the fan assembly along lines
14J-14J of FIG. 14; and
[0031] FIG. 14K is a sectional view of the fan assembly along lines
14K-14K of FIG. 14.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032] A motor/fan assembly is generally indicated by the numeral
10 in the accompanying drawings. As best seen in FIGS. 1-3, the
motor/fan assembly 10 includes a motor sub-assembly 12 and a fan
sub-assembly 14. It should be appreciated that the motor
sub-assembly 12 may be of any suitable conventional construction.
In one particular embodiment, the motor-subassembly 12 includes a
housing 16. The housing 16 may carry a concentrically positioned
bearing 18 which receives a shaft 20 therein. The shaft 20 carries
an armature 22 which is rotatably received within a commutator 24.
Shaft 20 further carries a cooling fan 26, which is positioned on
the end of shaft 20 proximate to fan/sub-assembly 14. Cooling fan
26 provides air flow over the internal motor components promoting
heat dissipation. The motor sub-assembly further includes a
plurality of field coils (not shown) as well as a plurality of
brushes 30. As is known in the art, these motor components interact
to cause shaft 20 to selectively rotate. As will be hereinafter
described, shaft 20 drives the working components of the fan
sub-assembly.
[0033] Referring now to FIGS. 4-7 and 10-14, fan sub-assembly 14
includes a base 32 coupled to the end of motor sub-assembly 12.
Base 32 may be generally circular and separates the motor
sub-assembly 12 from the various fan components by sealing around
shaft 20 in such a way that airflow generated by fan sub-assembly
14 is not contaminated by air or other matter from motor
sub-assembly 12. Base 32 may be provided with a plurality of ears
34 upon which an associated apparatus may be fastened. Further, one
or more mounting projections 35 may extend toward motor
sub-assembly 12 to enable coupling thereto.
[0034] Base 32 includes a curved outer flange 36 which defines the
radially outer surface thereof. Outer flange 36 may be provided
with a raised shoulder 38 that projects axially from and
circumferentially around the end 40 of outer flange 36. Shoulder 38
is received in the circumferential groove 42 of a shroud 44. In
this manner, shroud 44 is received by outer flange 36 forming a
generally airtight seal. Shroud 44, in cooperation with base 32,
forms an enclosed chamber 46 which receives the working fan
components. The shroud may be frictionally retained, staked or
otherwise secured by fasteners to the base 32.
[0035] Base 32 includes an inner plate 48 that extends radially
inward from flange 36 and faces chamber 46. Inner plate 48 includes
a shaft aperture 50 therethrough. A support ring 52 is provided at
the center of inner plate 48 around shaft aperture 50. Support ring
52 extends axially from inner plate 48, defining a boss 54 that
extends into chamber 46. A flange 56 extends inwardly from the
axial end of boss 54. A bearing 58 is received inside support ring
52 and is adapted to receive and support shaft 20 which rotates
therein. A seal 60 may be captured between bearing 58 and flange 56
to prevent contamination of the air passing through fan
sub-assembly 14. Seal 60 may be in any number of forms and could
utilize the teachings of U.S. Pat. Nos. 5,482,378 and/or 6,472,786,
both of which are incorporated herein by reference.
[0036] Shroud 44 is provided with a cylindrical port 62 which is
substantially concentric with the shaft 20. Port 62 is provided to
allow working air to enter the fan sub-assembly 14. Shroud 44
encloses a fan 64 that includes a plurality of blades 66 that
extend radially outwardly. Blades 66 may be straight, angled,
curved, or oriented in a sunburst pattern. Blades 66 are retained
between a disc 68 at a bottom edge of each blade and a ring 70 at a
top edge of each blade, wherein disc 68 has a central bore 72
permitting the fan 64 to be mounted to the shaft 20. Ring 70 has an
airflow aperture 74 aligned with and approximately the same size as
port 62 and in fluid communication therewith.
[0037] Fan 64 is spaced and coupled to shaft 20 by a plurality of
elements. A spacer 76 extends through aperture 50 and bears against
an inner race of bearing 58. Spacer 76 may be generally cylindrical
and is received around shaft 20. A first washer 78 is positioned
between spacer 76 and disc 68. A second washer 80 is positioned on
the opposed side of disc 68 and is secured thereto by a nut 82. Nut
82 may be provided at the end of shaft 20 and may be tightened
against second washer 80 which in turn clamps together the inner
race of bearing 58, spacer 76, first washer 78 and fan 64 so that
all turn as one unit with the shaft 20 as it is driven by motor
sub-assembly 12.
[0038] Shroud 44 includes a cap 86 that extends radially outward
from port 62. Cap 86 is frustoconical and shaped to generally
follow the upper profile of ring 70 resulting in minimal clearance
therebetween. This prevents unwanted turbulence, leaking and/or
bleeding of air moved by the fan 64. To further improve efficiency
and prevent leaks, a chamfer 86 is provided at the radial inner
edge of cap 86 that partially receives the upturned edge of ring
70.
[0039] A conduit wall 88 extends radially outwardly from cap 86 and
terminates at a downwardly turned lip 90 that includes
circumferential groove 42. It should thus be evident that conduit
wall 88 of shroud 44 includes an outer profile that mirrors that of
the outer profile of flange 36 of base 32. The area between conduit
wall 88 and base 32 defines a conduit 92 through which working air
travels during rotation of fan 64. As will become evident, the area
of conduit 92 grows larger as a function of circumferential
distance about base 32 from a minimum area (shown in FIG. 14A) to a
maximum area (shown in FIG. 14J). Conduit 92 begins at the minimum
area location and terminates at a horn 94, as shown sequentially in
FIGS. 14A-14K. Horn 94 includes a lower half 96 formed by base 32
and an upper half 98 formed by shroud 44. Horn 94 is substantially
circular in cross section and extends tangentially from base 32 and
shroud 44. The cross-sectional area of conduit 92 increases because
both the width and height increases as a function of
circumferential location. Thus, the radial distance of flange 36
from shaft 20 is not constant about the circumference and instead
is curvilinear. In other words, flange 36 varies from a minimum
radial distance (shown in FIG. 14A), to a maximum radial distance
(shown in FIG. 14 J). Further, conduit wall 88 includes a radiused
or upwardly curved cross-sectional shape. From minimum point (shown
in FIG. 14A) conduit 92 grows wider, as measured by the distance
between cap 84 and flange 36. Further, the channel grows taller, as
defined by the distance between inner plate 48 and the furthest
point on conduit portion 88.
[0040] When shaft 20 rotates, air is drawn in by the fan 64 into
chamber 46 via port 62. As fan 64 rotates, air is further drawn
through airflow aperture 74 and is urged radially outwardly by
blades 66. The air flow which is ejected radially from blades 66
has both a radial and tangential component. In other words, air
particles travel radially outwardly while at the same time spin
with the fan 64. Thus, when the air exits the fan 64, if the fan is
traveling in a counter-clockwise direction (as envisioned in the
present embodiment), the air correspondingly travels
circumferentially in a counter-clockwise direction around conduit
92. Because of the pressure differential between the outside
atmosphere and chamber 46, the air exits conduit 92 via horn 94.
Thus, as described above, air is drawn into port 62 and out of horn
94 upon rotation of shaft 20. Such systems are particularly useful
in common household vacuums, but may also find applications in many
other fields.
[0041] By varying the cross-sectional area of conduit 92 in the
manner discussed above, the kinetic energy stored in the moving air
can be converted more completely into static pressure, rather than
turbulence induced heat, due to the reduction of eddies as the air
leaves the rotating fan.
[0042] Based upon the foregoing, the advantages of the
constructions described above are readily apparent. In particular,
the conduit 92 is configured to provide a more efficient path for
air to travel within fan sub-assembly 14. In this manner fan
efficiency is increased, thus requiring less energy to provide the
same air flow. As a further result, motor life is extended. Thus,
the invention disclosed represents a great improvement in the art
of fan assemblies.
[0043] Thus, it can be seen that the objects of the invention have
been satisfied by the structure presented above. While in
accordance with the Patent Statutes, only the best mode and
preferred embodiment has been presented and described in detail, it
is to be understood that the invention is not limited thereto or
thereby. Accordingly, for an appreciation of the true scope and
breadth of the invention, reference should be made to the following
claims.
* * * * *