U.S. patent application number 11/712331 was filed with the patent office on 2008-08-28 for dual taper fan-motor assembly.
Invention is credited to David B. Finkenbinder, Harold A. Hughes.
Application Number | 20080206050 11/712331 |
Document ID | / |
Family ID | 39716112 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080206050 |
Kind Code |
A1 |
Finkenbinder; David B. ; et
al. |
August 28, 2008 |
Dual taper fan-motor assembly
Abstract
A motor-driven fan assembly includes a bracket which couples to
a motor assembly and includes an outlet port. A shroud assembly
defines a chamber and includes an inlet port. The shroud assembly
is received on a bracket and a bearing-supported shaft is driven by
the motor assembly and extends through the bracket and into the
shroud assembly. At least one fan is coupled to the shaft and
received in the chamber. The fan includes a plurality of curved
blades positioned between a frustoconical lower cap and an opposed
frustoconical upper cap. Rotation of the fan by the shaft results
in turbulent air flow through the fan assembly. Dust is generally
prevented from settling on the fan blades during operation, thereby
preventing non-uniform dust buildup or breakup which may cause
excessive vibration and reduce bearing and brush life.
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: |
39716112 |
Appl. No.: |
11/712331 |
Filed: |
February 28, 2007 |
Current U.S.
Class: |
415/208.2 |
Current CPC
Class: |
F04D 29/441 20130101;
A47L 5/22 20130101 |
Class at
Publication: |
415/208.2 |
International
Class: |
A47L 5/22 20060101
A47L005/22 |
Claims
1. A motor-driven fan assembly, comprising: a motor assembly; a
bracket coupled to said motor assembly, said bracket including an
outlet port; a shroud assembly which defines at least a chamber and
includes an inlet port, said shroud assembly adapted to be secured
to said bracket; a shaft rotated by said motor assembly, said shaft
extending through said bracket and into said shroud assembly; and
at least one fan coupled to said shaft and positioned in said
chamber, wherein said at least one fan includes a plurality of
curved blades positioned between an upper frustoconical cap and an
opposed lower frustoconical cap, said at least one fan moving air
from said inlet port to said outlet port.
2. The fan assembly according to claim 1, wherein said blades are
disposed between said caps in a curved sunburst arrangement
radiating radially outwardly.
3. The fan assembly according to claim 1, wherein said upper
frustoconical cap further comprises a disc shaped base secured at
its radial outer edge to a radial inner edge of said lower
frustoconical cap.
4. The fan assembly according to claim 3, wherein said base
includes a central aperture adapted to receive said shaft
therethrough.
5. The fan assembly according to claim 1, wherein said upper
frustoconical cap is substantially a mirror image in cross section
of said lower frustoconical cap.
6. The fan assembly according to claim 5, wherein said shroud
assembly further comprises a first shell and a second shell, said
first shell being secured to said second shell and said second
shell secured to said bracket, a first chamber formed between said
first shroud and said second shroud, and a second chamber formed
between said second shroud and said bracket.
7. The fan assembly according to claim 6, further comprising: a
stationary fan disposed between said first chamber and said second
chamber; and a second fan constructed substantially the same as
said first fan and coupled to said shaft and positioned in said
second chamber.
8. The fan assembly according to claim 1, wherein said upper
frustoconical cap comprises an aperture extending therethrough and
when said shaft rotates, air is drawn through said aperture and
radially outward across said blades.
9. A fan assembly, comprising: a shroud assembly that defines at
least one chamber and includes an inlet port that communicates with
said at least one chamber and an outlet port; a bracket coupled to
said shroud assembly, said bracket having an opening aligned with
said outlet port, said bracket having an aperture therethrough and
adapted to receive a rotatable shaft therethrough; and at least one
fan adapted to be coupled to the shaft and positioned in said at
least one chamber, wherein rotation of the shaft causes air to be
drawn into said inlet port and exhausted out said outlet port, and
wherein said at least one fan includes a plurality of curved blades
positioned between an angled upper cap and an opposed angled lower
cap.
10. The fan assembly according to claim 9, wherein each said blade
is disposed between said caps in a curved sunburst arrangement
radiating radially outwardly.
11. The fan assembly according to claim 9, wherein said upper
angled cap further includes a disc-shaped base secured at its
radial outer edge to a radial inner edge of said lower angled
cap.
12. The fan assembly according to claim 11, wherein said base
includes a central aperture adapted to receive the shaft
therethrough.
13. The fan assembly according to claim 12, wherein said upper
angled cap is a mirror image in cross section of said lower angled
cap.
14. The fan assembly according to claim 9, wherein said shroud
assembly further comprises a first shell and a second shell, said
first shell being secured to said second shell and said second
shell secured to said bracket, said first chamber being formed
between said first shell and said second shell, said second chamber
being formed between said second shell and said bracket, and
wherein said fan assembly further comprises a second fan,
substantially the same as said first fan, and adapted to be coupled
to the shaft and received in said second chamber.
15. The fan assembly according to claim 14, further comprising a
stationary fan carried by said second shell and including a
plurality of curved blades and a disc having a central bore,
wherein air expelled by said first fan is directed by said
stationary fan into said second fan.
Description
TECHNICAL FIELD
[0001] The present invention is generally directed to motor
assemblies. In particular, the present invention is directed to a
fan assembly of a motor assembly which increases motor efficiency
and air flow characteristics. Specifically, the present invention
is related to a multi-stage fan assembly with working air fans
having top and bottom tapers which promote efficiency and resist
contaminant buildup.
BACKGROUND ART
[0002] Vacuum motors employing multi-stage tapered fans 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 vacuums designs generally include a
cylindrical housing, or shroud, which encloses a pair of
motor-driven working air fans rotating about an axis.
[0003] As shown in prior art FIG. 1, such designs draw air into a
housing via an aperture A at the top axial center of the housing
above a first stage fan B. The first stage fan includes a plurality
of blades enclosed by a disc at the bottom and a frustoconical cap
at the top. Channels are thereby defined between adjoining blades
and, as the fan rotates, the air is accelerated through the
channels in the circumferential and radially outward direction. The
air is then directed into a second stage which includes a second
stage fan C. The second stage fan may be generally identical to the
first stage fan and includes a plurality of blades enclosed by a
disc at the bottom and a frustoconical cap. Air is again
accelerated through the channels defined by adjoining blades in the
circumferential and radially outward direction. The housing
provides an outlet located proximal the fan opposed to the
aperture.
[0004] As is evident from FIG. 1, such fans may be tapered along
the top surface defined by the frustoconical cap. In this manner
the cross-sectional height of the fan becomes smaller as a function
of radial distance from the axis of rotation. This in turn results
in constriction in the channel volumes as a function of radial
distance from the axis of rotation. This feature was provided to
improve airflow properties and improve efficiency. While the
tapering of the top frustoconical cap of such fans have been found
to improve airflow, certain drawbacks persist. Specifically,
assemblies of this nature have areas between the adjoining blades
where airflow is virtually non-existent. As such, contaminants such
as dust and debris collect in the rotating working air fans. This
is particularly a concern when air drawn into the fan assembly
carries a dust and water mixture such as would be seen in a wet/dry
vacuum. Collection and retention of the contaminants in the fan
causes the fan to become unbalanced. This adds stress to the
rotating shaft and excess vibration which prematurely wears the
motor brushes. Over time, these problems lead to bearing damage and
eventual fan and/or motor assembly failure. Thus, while such fans
are efficient in terms of airflow and have a small profile, the
aforementioned drawbacks persist.
[0005] Therefore, there exists a need in the art for a fan assembly
which minimizes dust and contaminate collection on the working air
fans and therefore extends the life of the fan assembly.
SUMMARY OF THE INVENTION
[0006] In view of the foregoing, it is a first aspect of the
present invention to provide a motor fan which achieves improved
efficiency.
[0007] Another aspect of the present invention is to provide a
motor-driven fan assembly comprising a motor assembly, a bracket
coupled to the motor assembly, the bracket including an outlet
port, a shroud assembly which defines at least a chamber and
includes an inlet port, the shroud assembly adapted to be secured
to the bracket, a shaft rotated by the motor assembly, the shaft
extending through the bracket and into the shroud assembly, and at
least one fan coupled to the shaft and positioned in the chamber,
wherein the at least one fan includes a plurality of curved blades
positioned between an upper frustoconical cap and an opposed lower
frustocinical cap, the at least one fan moving air from the inlet
port to the outlet port.
[0008] Yet another aspect of the present invention is to provide a
fan assembly comprising a shroud assembly that defines at least one
chamber and includes an inlet port that communicates with the at
least one chamber and an outlet port, a bracket coupled to the
shroud assembly, the bracket having an opening aligned with the
outlet port, the bracket having an aperture therethrough and
adapted to receive a rotatable shaft therethrough, and at least one
fan adapted to be coupled to the shaft and positioned in the at
least one chamber, wherein rotation of the shaft causes air to be
drawn into the inlet port and exhausted out the outlet port, and
wherein the at least one fan includes a plurality of curved blades
positioned between an angled upper cap and an opposed angled lower
cap.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] 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:
[0010] FIG. 1 is a sectional view of a prior art fan/motor
assembly;
[0011] FIG. 2 is an end view of a fan/motor assembly made in
accordance with the concepts of the present invention;
[0012] FIG. 3 is a sectional view of the fan/motor assembly made in
accordance with the concepts of the present invention;
[0013] FIG. 4 is an exploded sectional view of the fan/motor
assembly made in accordance with the concepts of the present
invention;
[0014] FIG. 5 is a top plan view and partial breakaway view of an
exemplary rotating fan;
[0015] FIG. 6 is a side plan view of an exemplary rotating fan;
and
[0016] FIG. 7 is a top plan view of an exemplary stationary
fan.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017] Referring now to the drawings and more particularly to FIGS.
2-4, it can be seen that a motor/fan assembly made in accordance
with the invention is designated generally by the numeral 10. The
motor/fan assembly 10 of the present invention includes a motor
sub-assembly 11 and a fan sub-assembly 12. It should be appreciated
that this disclosure is generally directed towards the fan
sub-assembly, and thus the motor sub-assembly 11 may be of any
suitable conventional construction. In one embodiment, the motor
sub-assembly 11 includes a housing 13. The motor housing 13 may
provide a commutator bracket which carries a concentrically
positioned bearing 14 which receives a shaft 15 therein. The shaft
15 supports an armature 16 and a commutator 17 thereon, as well as
a number of fans as will be hereinafter discussed. As is known in
the art, these motor components interact to cause shaft 15 to
selectively rotate and drive the working components of fan
sub-assembly 12.
[0018] An end bracket 30 is provided on the end of motor
sub-assembly 11 opposite the motor housing 13. End bracket 30 may
be generally circular and is provided to enable fan components to
be coupled to the motor sub-assembly 11. End bracket 30 includes an
outer flange 32 which defines the radially outer surface thereof. A
notched portion 34 may be provided circumferentially around outer
flange 32. At least one outlet 36, in the form of a tangential
horn, is provided in end bracket 30. While the outlet of the
present embodiment faces a direction tangent to the central shaft
axis, it should be appreciated that other outlet designs may be
employed. For example, a plurality of radially or axially facing
ports may be employed which achieve substantially the same results
for exhausting air from fan sub-assembly 12.
[0019] The shaft 15, which is operatively coupled to the above
mentioned motor elements, extends through and is supported by end
bracket 30. Accordingly, end bracket 30 includes a support ring 38
which is formed with a generally cylindrical body 40, and a flange
42 that projects radially inward from cylindrical body 40. Flange
42 defines an axially oriented opening 44 which is sized to allow
shaft 15 to extend therethrough. The cylindrical body 40 is adapted
to receive a bearing 46 therein that in turn rotatably receives
shaft 15 therethrough. Shaft 15 is thus supported by end bracket 30
via bearing 46, which allows for rotation therein. Various types of
seals may be employed between the end bracket and the shaft to
protect the bearing from moisture and dirt.
[0020] Fan sub-assembly 12, which is supported by the end bracket
30, includes a shroud assembly 52 which encloses a plurality of
fans as will be hereinafter discussed. It should be appreciated
that, while embodiments shown in FIGS. 3 and 4 employ two working
air fans, any number might be employed, and multiple fans could be
stacked in the manner disclosed below. Shroud assembly 52 includes
a first shell 54 that is positioned at the axial end of fan
sub-assembly 12, opposite the end bracket 30. First shell 54
includes an outer wall 56 which is substantially cylindrical and
centered about the axis defined by shaft 15. Outer wall 56
terminates at a radiused edge 58 that transitions to a generally
flat axially facing wall 60. Facing wall 60 is annular and extends
radially inwardly from radiused edge 58. Facing wall 60 defines an
axially centered inlet port 62. Inlet port 62 provides the opening
through which working air enters fan sub-assembly 12.
[0021] Shroud assembly 52 further includes a second shell 70 that
includes an outer wall 72 that is substantially cylindrical and
centered about the axis defined by shaft 15. As shown in FIG. 3,
outer wall 56 of first shell 54 is received over a portion of outer
wall 72 and rests against a step 74. Step 74 acts as a stop,
against which the rim of outer wall 56 rests. In this manner the
first shell 54 is stacked atop the second shell 70. Outer wall 72
terminates at a chamfered edge 76 which transitions to an axially
facing base wall 78. Base wall 78 is generally disc shaped and
projects radially inward from outer wall 72. An opening 80 is
provided at the concentric center of base wall 78. As is evident
from FIG. 3, the first shell 54 and second shell 70 define a first
chamber 82, access to which is provided at inlet port 62 and
opening 80. Further, second shell 70 and end bracket 30 define a
second chamber 84, access to which is provided at inlet port
opening 80 and outlet 36.
[0022] As earlier discussed, shroud assembly 52 encloses a
plurality of fans. First chamber 82 encloses a first working air
fan 90, hereinafter first fan 90. First fan 90 includes lower cap
92 in the form of a frusto-conical disc. In other words, in
cross-section, lower cap 92 includes a profile that is oriented at
an angle other than 90 degrees relative to the axis defined by
shaft 15. Lower cap 92 terminates at it's radial inner surface at a
base 94, which is in the form of an axially facing disc. Base 94 is
rotationally coupled to shaft 15 and, to that end, is provided with
a central bore 96 that is sized to receive shaft 15
therethrough.
[0023] First fan 90 also includes an upper cap 98 in the form of a
frusto-conical disc. In other words, in cross-section, upper cap
includes a profile that is oriented at an angle other than 90
degrees relative to the axis defined by shaft 15. Upper cap 98
defines an aperture 100 that is centrally aligned with the axis
defined by shaft 15. Aperture 100 is sized to be approximately the
same diameter as inlet port 62. As is evident from FIGS. 4 and 6,
upper cap 98 and lower cap 92 may include generally linear
cross-sections. Further, it should be appreciated that the opposed
caps 92 and 98 are oriented such that the distance therebetween
grows smaller with radial distance away from the axis defined by
shaft 15. Still further, in one or more embodiments lower cap 92
is, in cross section, a mirror image of upper cap 98.
[0024] As shown in FIG. 5, a plurality of blades 102 are secured
between lower cap 92 and upper cap 98, each being disposed in a
curved sunburst arrangement radiating outwardly towards outer wall
56. Each blade 102 includes a leading edge 104 that is spaced from
shaft 15, thus defining a fan eye 106. Each blade 102 terminates
proximate to the outer radial edge of lower cap 92 and upper cap 98
at a trailing edge 108. When shaft 15 rotates in a
counter-clockwise direction, the blades 102 shown in FIG. 5 further
define a leading surface 110 which is opposite a trailing surface
112, as will be discussed later in more detail. In one or more
embodiments, the blade 102 may be coupled to upper and lower caps
92 and 98 by a plurality of stakes or rivets which are received in
corresponding holes along caps 92 and 98. Each blade 102 is tapered
at both the bottom and top. In other words, the height of blades
102 grows smaller as radial distance from shaft 15 increases. In
embodiments where lower and upper caps 92 and 98 are linear, the
height will correspondingly be reduced linearly as radial distance
increases. Each adjoining blade 102 defines a channel 114
therebetween, that provides a path for airflow during fan
operation.
[0025] First chamber 82 also encloses a stationary fan 116, carried
by second shell 70. As seen in FIG. 7, stationary fan 116 includes
a plurality of blades 118 which may be oriented in a sunburst
arrangement radiating outwardly towards outer wall 56. A disc 120
is positioned along the top surface of blades 118 and includes a
central bore 122 which allows shaft 15 to extend therethrough.
Blades 118 extend radially inward from the outer radial edge of
disc 120 and end at the central opening 80 of second shell 70.
[0026] The central opening 80 of second shell 70 communicates with
a second working air fan130, hereinafter second fan 130, which is
enclosed within second chamber 84. Second fan 130 may be
substantially identical to first working air fan 104. Thus, second
fan includes lower cap 132 in the form of a frusto-conical disc. In
other words, in cross-section, lower cap 132 includes a profile
that is oriented at an angle other than 90 degrees relative to the
axis defined by shaft 15. Lower cap 132 terminates at it's radial
inner surface at a base 134 in the form of an axially facing disc.
Base 134 is rotationally coupled to shaft 15 and, to that end, is
provided with a central bore 136 that is sized to receive shaft 15
therethrough.
[0027] Second fan 130 also includes an upper cap 138 in the form of
a frusto-conical disc. In other words, in cross-section, upper cap
138 includes a profile that is oriented at an angle other than 90
degrees relative to the axis defined by shaft 15. Upper cap 138
defines an aperture 140 that is centrally aligned with the axis
defined by shaft 15. Aperture 140 is sized to be approximately the
same diameter as inlet port 80. As is evident from FIGS. 4 and 6,
upper cap 138 and lower cap 132 may include generally linear
cross-sections. Further, it should be appreciated that the opposed
caps 132 and 138 are oriented such that the distance therebetween
grows smaller with radial distance away from the axis defined by
shaft 15. Still further, in one or more embodiments lower cap 132
is, in cross section, a mirror image of upper cap 138.
[0028] As shown in FIG. 5, a plurality of blades 142 are secured
between lower cap 132 and upper cap 138, each being disposed in a
curved sunburst arrangement radiating outwardly towards outer wall
72. Each blade 142 includes a leading edge 144 that is spaced from
shaft 15, thus defining a fan eye 146. Each blade 142 terminates
proximate to the outer radial edge of lower cap 132 and upper cap
138 at a trailing edge 148. When shaft 15 rotates in a
counter-clockwise direction, the blades 142 of FIG. 5 further
define a leading surface 150 and a trailing surface 152, as will be
discussed later in more detail. In one or more embodiments, the
blades 142 may be coupled to upper and lower caps 132 and 138 by a
plurality of stakes or rivets (not shown) which are received in
corresponding holes along caps 132 and 138. Each blade 142 is
tapered along both the respective bottom and top edges. In other
words, the height of blades 142 grow smaller as radial distance
from shaft 15 increases. In embodiments where lower and upper caps
132 and 138 are linear, the height will correspondingly be reduced
linearly as radial distance increases. Each adjoining blade 142
defines a channel 154 therebetween, that provides a path for
airflow during fan operation. second working air fan 142 includes a
base 144 in the form of a disc.
[0029] In the present embodiment, the aforementioned fans 90 and
130 are spaced and coupled to the shaft 15 by a plurality of
elements. A T-spacer 160 extends inwardly through opening 44 in
support ring 38 and bears against or is adjacent to an inner race
of bearing 46. T-spacer 160 may have a generally T-shaped cross
section to provide an enlarged transverse surface against which the
base 146 of second fan 130 may bear. Positioned between fans 90 and
130 is an I-spacer 162 which is received on shaft 15 and may have a
generally I-shaped cross section. A washer 164 may be provided at
the end of shaft 15 that includes a notched portion 166 that rests
against a corresponding notched portion 168 of shaft 15. A nut 170
may be provided at the end of shaft 15 that may be tightened
against washer 164 which in turn bears against base 94 of first
working air fan 90. This in turn clamps together the inner race of
the bearing 46, T-spacer 160, I-spacer 162, fans 90 and 130 and
washer 164 so that all turn as one unit with the shaft 15 as it is
driven by the motor sub-assembly 11. In this manner, when shaft 15
rotates counter-clockwise, air is drawn into first chamber 82 via
inlet port 62. Air is then drawn into eye 106 and is urged radially
outward by blades 102. Once the air is ejected radially outwardly
past blades 102, blades 118 of the stationary fan 116 direct the
air flow radially inward toward opening 80. As is evident from FIG.
3, opening 80 directs the air flow into second chamber 84. As
second fan 130 rotates, blades 142 again urge the air radially
outward. Because of the pressure differential between the outside
atmosphere and the second chamber 84, the air exits second chamber
84 via outlet port 36. Thus, as described above, air is drawn into
inlet port 62 and out of outlet port 36 upon counter-clockwise
rotation of shaft 15.
[0030] Of particular concern in such fans is the collection of dust
and other particles within the working air fans. The profile of fan
blades 102 and 142 in the configuration disclosed greatly reduces
contaminants from sticking to fan blades. Indeed, the dual taper
design could be used in a single fan configuration. It has been
found that in conventional multi-stage fans, dust and debris tend
to stick to the leading surface 110 or 150 as air travels radially
outward from the eye 106 or 146 of the fan. By reducing the height
of the blades 102 and 142 and correspondingly including angled
lower caps 92/132 and upper caps 98/138 so that the blades are
tapered at both sides, the cross sectional area of channels 114 and
154 are thus reduced. The reduction in channel area of the present
invention is thus reduced more quickly than in a prior art fan.
Consequently, the particles in the air are accelerated faster than
a traditional fan. Because the air is accelerated faster as it
travels radially outward, any particles or contaminates in the air
are ejected from the fan and not given an opportunity to stick to
the leading surface 110 or 150. In other words, the channels formed
by the dual taper blades and the frusto-conical caps generate a
continually increasing pressure gradient from where the air enters
the channels proximal the inlet to where the air exits the channels
at the outer radial edges of the caps. Such a configuration is
believed to generate turbulence within the entire channel, thus
preventing accumulation of any debris. Thus, when such a dual blade
taper is employed with a multi-stage working air fan design, the
incidence of fan contamination is greatly reduced. This in turn
leads to increased fan and bearing life. Specifically, uneven
contaminate buildup, or buildup which suddenly breaks away from the
blades, can cause vibration, which degrades bearing life. By
preventing contaminates from sticking to the blades, this vibration
is limited and bearing life is increased.
[0031] 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.
* * * * *