U.S. patent application number 10/924532 was filed with the patent office on 2005-07-21 for pivotal direct drive motor for exhaust assembly.
Invention is credited to Hrdina, Terry Lee, Koeppel, Scott James, Seliger, Michael Glenn.
Application Number | 20050159101 10/924532 |
Document ID | / |
Family ID | 34753704 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050159101 |
Kind Code |
A1 |
Hrdina, Terry Lee ; et
al. |
July 21, 2005 |
Pivotal direct drive motor for exhaust assembly
Abstract
An exhaust assembly is provided for expelling contaminated air
from a building. The assembly includes a plenum, a fan assembly
attached to the plenum, and a windband mounted on top of the fan
assembly. The fan assembly is constructed of cylindrical outer and
inner walls which define a drive chamber and surrounding annular
space. A fan driven by a motor whose shaft extends downward from
the drive chamber draws exhaust air from the plenum and blows it up
through the annular space to a nozzle at the top of the fan
assembly. The motor is pivotally mounted inside the assembly to
provide access to the motor components when it is desired to
perform inspection and maintenance.
Inventors: |
Hrdina, Terry Lee; (Wausau,
WI) ; Koeppel, Scott James; (Wausau, WI) ;
Seliger, Michael Glenn; (Marathon, WI) |
Correspondence
Address: |
QUARLES & BRADY LLP
411 E. WISCONSIN AVENUE
SUITE 2040
MILWAUKEE
WI
53202-4497
US
|
Family ID: |
34753704 |
Appl. No.: |
10/924532 |
Filed: |
August 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60537609 |
Jan 20, 2004 |
|
|
|
60588074 |
Jul 15, 2004 |
|
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Current U.S.
Class: |
454/356 |
Current CPC
Class: |
F04D 25/02 20130101;
F24F 7/025 20130101 |
Class at
Publication: |
454/356 |
International
Class: |
F24F 007/007 |
Claims
We claim:
1. An exhaust assembly which comprises: an outer wall that defines
a cavity therein having an air inlet formed at its bottom end; an
inner wall fastened to the outer wall and positioned in the cavity
to divide it into a centrally located chamber and a surrounding
annular space; a fan chamber disposed at the bottom of the cavity,
the fan chamber retaining a fan coupled to a fan shaft to draw
exhaust air in through the air inlet and blow it upward through the
annular space; a drive chamber disposed inside the outer wall and
adjacent the fan chamber; and a motor pivotally mounted in the
drive chamber, the motor pivotable between a first engaged position
in which a motor shaft is coupled to the fan shaft for driving the
fan, and a second disengaged pivoted position.
2. The exhaust assembly as recited in claim 1 in which the motor is
mounted to a plate supported in the drive chamber by a mounting
bracket.
3. The exhaust assembly as recited in claim 2 in which the mounting
bracket is fastened to the plate by a hinge that permits pivotal
movement of the mounting bracket relative to the plate.
4. The exhaust assembly as recited in claim 3 in which the mounting
bracket is further fastened to the plate by removable
fasteners.
5. The exhaust assembly as recited in claim 3 in which a passageway
is formed into the drive chamber from outside the assembly by a
passage wall that extends through the annular space between the
inner and outer walls to provide access to the motor for inspection
or repair.
6. The exhaust assembly as recited in claim 5 in which a second
passageway is formed into the drive chamber from outside the
assembly by a second passage wall that extends through the annular
space between the inner and outer walls.
7. The exhaust assembly as recited in claim 6 in which the motor is
pivotable towards one of the passageways.
8. The exhaust assembly as recited in claim 6, wherein the hinge
extends in a direction substantially perpendicular to an axis
extending between the passageways.
9. The exhaust assembly as recited in claim 1 in which a passageway
is formed into the drive chamber from outside the assembly by a
passage wall that extends through the annular space between the
inner and outer walls to provide access to the motor for inspection
or repair.
10. The exhaust assembly as recited in claim 9 in which a second
passageway is formed into the drive chamber from outside the
assembly by a second passage wall that extends through the annular
space between the inner and outer walls, and ambient air is drawn
into the passageways and flows out the top end of the inner wall to
mix with the exhaust air.
11. The exhaust assembly as recited in claim 1 in which a roof is
disposed in the drive chamber and above the motor to protect the
same from substances entering the top end of the inner wall.
12. The exhaust assembly as recited in claim 11 in which the roof
is sloped.
13. The exhaust assembly as recited in claim 1 in which the inner
wall is spaced upward from the air inlet to form the fan
chamber.
14. The exhaust assembly as recited in claim 1, wherein the drive
chamber is disposed above the fan chamber.
15. An exhaust assembly as recited in claim 1, the annular space
being constricted at the top of the outer wall to form a
nozzle.
16. The exhaust assembly as recited in claim 1 which includes a
plenum fastened to the outer wall and disposed beneath the air
inlet, the plenum includes: a housing having an upper housing wall
with an exhaust outlet that aligns with the air inlet and a bottom
housing wall with an exhaust inlet for receiving exhaust air from a
building; and a bypass air inlet formed in one wall of the housing
for receiving ambient air.
17. The exhaust assembly as recited in claim 16 in which a damper
is mounted in the plenum to control the amount of ambient air
entering through the bypass air inlet.
18. The exhaust assembly as recited in claim 16 in which the outer
wall is removably fastened to the plenum to enable removal thereof
for repair or replacement.
19. The exhaust assembly as recited in claim 18 which includes a
removable access panel formed in one side wall of the plenum
housing.
20. The exhaust assembly as recited in claim 1 in which the upper
end of the inner wall is flared radially outward to form said
nozzle.
21. The exhaust assembly as recited in claim 1 which includes a
windband mounted to the upper end of the outer wall, the windband
having a frustum-shape with a circular opening at its lower end
which is coaxial with said nozzle and the lower end is
substantially coplanar with a nozzle formed by a constriction at
the top of outer wall.
22. The exhaust assembly as recited in claim 21 in which the lower
end of the windband is flared radially outward to form an inlet
bell.
23. The exhaust assembly as recited in claim 21 in which a
cylindrical ring is formed at the upper end of the windband.
24. The exhaust assembly as recited in claim 1 in which the inner
wall extends upward above a nozzle formed from a constriction of
the top of the outer wall, and which includes: a second nozzle
assembly mounted to the inner wall and having a frustum shape with
a circular opening at its top end which is coaxial with the inner
wall and coplanar with the top end of the inner wall; and a
windband mounted to the second nozzle assembly and having a frustum
shape with a circular opening at its lower end which is coaxial
with the inner wall and coplanar with the top end of the inner
wall.
25. The exhaust assembly as recited in claim 23, in which the
second nozzle assembly has a circular opening at its lower end
which is coaxial with the inner wall and coplanar with the
nozzle.
26. An exhaust assembly mounted onto a roof of a building for
removing contaminated air from one or more building exhaust vents,
the exhaust assembly comprising: an air inlet receiving the
contaminated air, at least one ambient air entrainment zone mixing
ambient air with the contaminated air to produce diluted air, and
an air outlet exhausting the diluted air; a fan coupled to a fan
shaft to draw the contaminated air through the air inlet and blow
it towards the air outlet; and a pivotally mounted motor driving a
motor shaft removably coupled to the fan shaft.
27. The exhaust assembly as recited in claim 26 further comprising
a housing is formed from an outer wall defining a cavity and an
inner wall disposed in the cavity and spaced from the outer wall to
divide the cavity into a central chamber and a surrounding annular
space.
28. The exhaust assembly as recited in claim 27 in which the
central chamber is divided into a fan chamber housing the fan, and
a drive chamber housing the motor.
29. The exhaust assembly as recited in claim 28 in which the drive
chamber is disposed above the fan chamber.
30. The exhaust assembly as recited in claim 27 in which a pair of
opposing passageways extend through the inner and outer walls to
enable access to the motor.
31. The exhaust assembly as recited in claim 30 in which the motor
is pivotable towards and away from at least one of the
passageways.
32. The exhaust assembly as recited in claim 31 in which ambient
air is drawn into the passageways and flows out the top end of the
inner wall to mix with the exhaust air.
33. The exhaust assembly as recited in claim 30 in which the motor
is supported on a housing plate by a mounting bracket connected to
the plate by a hinge.
34. The exhaust assembly as recited in claim 33 in which the hinge
extends in a direction substantially perpendicular to an axis
extending between the passageways.
35. The exhaust assembly as recited in claim 33 in which the
mounting bracket is further fixed to the plate by at least one
removable fastener.
36. An exhaust assembly which comprises: a housing separating a
drive chamber from a fan chamber, the housing defining an inlet end
and an outlet end; a motor pivotally mounted in the drive chamber,
the motor including a motor shaft; a fan disposed in the fan
chamber and coupled to a fan shaft that is, in turn, coupled to the
motor shaft to draw air through the air inlet and blow it towards
the outlet, and at least one passageway extending through the
housing, the passageway providing access to the motor.
37. The exhaust assembly as recited in claim 36 in which the motor
is pivotal towards and away from the passageway.
38. The exhaust assembly as recited in claim 36 in which the motor
is supported on a plate in the drive chamber.
39. The exhaust assembly as recited in claim 38 in which the motor
is supported on the plate by a mounting bracket that is connected
to the plate by a hinge.
40. The exhaust assembly as recited in claim 39 in which the hinge
extends in a direction substantially perpendicular to an axis
extending between the passageways.
41. The exhaust assembly as recited in claim 39 in which the
mounting bracket is further fixed to the plate by at least one
removable fastener.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This claims the benefit of U.S. Provisional Patent
Application No. 60/537,609 filed Jan. 20, 2004 and further claims
the benefit of U.S. Provisional Patent Application No. 60/558,074
filed Jul. 15, 2004, the disclosure of each of which is hereby
incorporated by reference as if set forth in their entirety
herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to exhaust fans, and
more particularly to exhaust fans of the type that draw
contaminated air from one or more fume hoods dispersed throughout a
building, mix the contaminated air with ambient air to dilute the
contaminants, and vent the diluted air from the building into the
ambient environment.
[0003] There are many different types of exhaust systems for
buildings. In most of these the objective is to simply draw air
from inside the building in an efficient manner. In building such
as laboratories, fumes are produced by chemical and biological
processes, which may have an unpleasant odor, is noxious or toxic.
One solution is to exhaust such fumes through a tall exhaust stack
which releases the fumes far above ground and roof level. Such
exhaust stacks, however, are expensive to build and are
unsightly.
[0004] Another solution is to mix the fumes with fresh air to
dilute the contaminated air, and exhaust the diluted air upwards
from the top of the building at a high velocity. The exhaust is
thus diluted and blown high above the building. Examples of such
systems are described in U.S. Pat. Nos. 4,806,076; 5,439,349 and
6,112,850. Unfortunately, prior systems are expensive, difficult to
maintain and not easily adaptable to meet a wide range of
performance specifications.
BRIEF SUMMARY OF THE INVENTION
[0005] In accordance with one aspect of the present invention, an
exhaust assembly is provided including an outer wall that defines a
cavity therein having an air inlet formed at its bottom end, and an
inner wall fastened to the outer wall and positioned in the cavity
to divide it into a centrally located chamber and a surrounding
annular space. A fan chamber is disposed at the bottom of the
cavity and retains a fan coupled to a fan shaft to draw exhaust air
in through the air inlet and blow it upward through the annular
space. A drive chamber is disposed inside the outer wall and
adjacent the fan chamber. A motor is pivotally mounted in the drive
chamber. The motor is pivotable between a first engaged position in
which a motor shaft is coupled to the fan shaft for driving the
fan, and a second disengaged pivoted position.
[0006] In accordance with another aspect of the invention, an
exhaust assembly is mounted onto a roof of a building for removing
contaminated air from one or more building exhaust vents. The
exhaust assembly includes an air inlet receiving the contaminated
air, at least one ambient air entrainment zone mixing ambient air
with the contaminated air to produce diluted air, and an air outlet
exhausting the diluted air. A fan is coupled to a fan shaft to draw
the contaminated air through the air inlet and blow it towards the
air outlet. A pivotally mounted motor drives a motor shaft that is
removably coupled to the fan shaft.
[0007] In accordance with yet another aspect of the invention, an
exhaust assembly includes a housing separating a drive chamber from
a fan chamber. A motor is pivotally mounted in the drive chamber,
and includes a motor shaft. The housing defines an inlet end and an
outlet end. A fan is disposed in the fan chamber and coupled to a
fan shaft that is, in turn, coupled to the motor shaft to draw air
through the air inlet and blow it towards the outlet. At least one
passageway extends through the housing. The passageway provides
access to the motor.
[0008] In the following description, reference is made to the
accompanying drawings, which form a part hereof, and in which there
is shown by way of illustration, and not limitation, a preferred
embodiment of the invention. Such embodiment also does not define
the scope of the invention and reference must therefore be made to
the claims for this purpose.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Reference is hereby made to the following drawings in which
like reference numerals correspond to like elements throughout, and
in which:
[0010] FIG. 1 is a schematic perspective view of a building
ventilation system constructed in accordance with principles of the
present invention;
[0011] FIG. 2 is a side elevation view of an exhaust assembly
constructed in accordance with the preferred embodiment;
[0012] FIG. 3 is a perspective view with parts cut away of the
plenum which forms part of the exhaust assembly of FIG. 2;
[0013] FIG. 4 is a perspective view of a housing which forms part
of the plenum of FIG. 3;
[0014] FIGS. 5A-5E are views of the plenum which forms part of the
exhaust assembly of FIG. 2;
[0015] FIGS. 6A-6B are exploded views of the plenum of FIGS. 5A-5E
showing the dampers therein.
[0016] FIG. 7 is a sectional side elevation view of the exhaust
assembly illustrated in FIG. 2;
[0017] FIG. 8 is an exploded perspective view of the fan assembly
of FIG. 7;
[0018] FIG. 9 is an enlarged sectional side elevation view similar
to FIG. 7 but illustrating the fan motor in a pivoted position;
[0019] FIG. 10 is a partial view of the fan assembly of FIG. 7 with
parts cut away;
[0020] FIG. 11 is a view in cross-section taken along the plane
11-11 shown in FIG. 7;
[0021] FIG. 12 is a view in cross-section taken along the plane
12-12 shown in FIG. 7;
[0022] FIG. 13 is a view in cross-section taken along the plane
13-13 shown in FIG. 7;
[0023] FIG. 14 is a view in cross-section taken along the plane
14-15 shown in FIG. 7;
[0024] FIG. 15 is a schematic diagram of the fan assembly showing
the parameters which determine the desired performance;
[0025] FIG. 16 is a pictorial view with parts cut away of a second
embodiment of the exhaust assembly of the present invention;
and
[0026] FIG. 17 is an elevation view of the exhaust assembly of FIG.
16.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0027] Referring initially to FIG. 1, a building ventilation system
20 includes one or more fume hoods 22 of the type commonly
installed in commercial kitchens, laboratories, manufacturing
facilities, or other appropriate locations throughout a building
that create noxious or other gasses that are to be vented from the
building. In particular, each fume hood 22 defines a chamber 28
that is open at a front of the hood for receiving surrounding air.
The upper end of chamber 28 is linked to the lower end of a conduit
32 that extends upwards from the hood 22 to a manifold 34. Manifold
34 is further connected to a riser 38 that extends upwards to a
roof 40 or other upper surface of the building. The upper end of
riser 38 is, in turn, connected to an exhaust assembly 42 that is
mounted on top of roof 40 and extends upwards away from the roof
for venting gasses from the building.
[0028] Referring also to FIG. 2, exhaust assembly 42 includes a
plenum 44 disposed at the base of the assembly that receives
exhaust from riser 38 and mixes it with fresh air. A fan assembly
46 is connected to, and extends upwards from, plenum 44. Fan
assembly 46 includes a fan wheel that draws exhaust upward through
the plenum 44 and blows it out through a windband 52 disposed at
its upper end. Each of these components is described in more detail
below. During operation, exhaust assembly 42 draws an airflow that
travels from each connected fume hood 22, through chamber 28,
conduits 32, manifold 34, riser 38 and plenum 44. This exhaust air
is mixed with fresh air before being expelled upward at high
velocity through an opening in the top of the windband 52.
[0029] The control of this system typically includes both
mechanical and electronic control elements. A conventional damper
36 is disposed in conduit 32 at a location slightly above each hood
22, and is automatically actuated between a fully open orientation
(as illustrated) and a fully closed orientation to control exhaust
flow through the chamber 28. Hence, the volume of air that is
vented through each hood 22 is controlled.
[0030] The building can be equipped with more than one exhaust
assembly 42, each such assembly 42 being operably coupled either to
a separate group of fume hoods 22 or to manifold 34. Accordingly,
each exhaust assembly 42 can be responsible for venting noxious
gasses from a particular zone within the building 26, or a
plurality of exhaust assemblies 42 can operate in tandem off the
same manifold 34. In addition, the manifold 34 may be coupled to a
general room exhaust in building 26. An electronic control system
(not shown) may be used to automatically control the operation of
the system.
[0031] Referring now to FIGS. 3-5E, plenum 44 includes a
rectangular housing having a horizontal upper wall 54 that includes
an exhaust outlet 92 from the plenum 44, and an opposing lower wall
56 that includes an exhaust inlet 64. A pair of opposing vertical
side walls 58 and an integrally connected vertical rear wall 60
extend between the upper and lower walls 54 and 56 to define an
internal mixing chamber 59.
[0032] Plenum 44 further includes a vertical front wall 62 disposed
opposite the rear wall 60. A hood 66 extends outwardly from front
wall 62 to provide a bypass air inlet extending through an opening
82 extending through wall 62, and into chamber 59. The hood 66
includes opposing vertical side walls 68, a horizontal lower wall
72, and an opposing angled upper wall 70 that together define a
front opening that can be covered by a front porous screen 74 that
enables ambient (bypass) air to flow through and into plenum 44.
Upper wall 70 is angled down from the upper end of the plenum front
wall 62, and extends out a distance beyond lower hood wall 27 to
provide a rain hood that protects the interior plenum components
from entrainment of snow, water, and debris. An upward-turned lip
79 that surrounds the outer periphery of upper wall 70 (See FIG.
5C) prevents water from spilling into the bypass air stream.
[0033] A damper 84 is mounted in an opening 82 formed in the plenum
front wall 62 and beneath the hood 70. Damper 84 includes damper
blades 86 that are controlled to regulate the flow rate of fresh
air into plenum 44. This flow of fresh air is indicated by Arrow B
in FIG. 3. Damper 84 can be controlled electronically to enable a
flow of bypass air into plenum 44, which ensures that the total air
flow through the fan assembly 46 remains constant despite
fluctuations in the flow rate of exhaust air to be removed from the
building via exhaust assembly 42.
[0034] The exhaust air and bypass air mix inside chamber 59 to
produce once-diluted exhaust air that travels upwards through
exhaust outlet 92 to the fan assembly 46 as indicated in FIG. 3 by
Arrow C. A support bracket 88 extends horizontally across the inner
surfaces of walls 58, 60, and 62 at the upper end of chamber 59,
and collectively support an isolation damper 90 that isolates the
outdoor ambient air entering through the fan assembly 46 when the
fan is not in operation. As shown best in FIGS. 6A and 6B the
isolation damper 90 is slidably attached to the plenum 44. The
damper 90 may be activated by gravity backdraft or it may be
activated by a shaft as well known by a skilled artisan.
[0035] In an alternative embodiment the riser 38 (FIG. 1) may be
extended above the roof 40 and connected to an inlet opening formed
in a side wall 58 of the plenum 44.
[0036] Referring particularly to FIG. 4, a gutter is formed around
the interior base perimeter of the plenum chamber 59 to collect and
drain liquid. The gutter is formed by a flange 89 that extends
inward from walls 58, 60, and 62 at the lower end of chamber 59,
and a lip 91 that extends up from the inner edge of flange 89.
Gutter is linked to a drain 95 extending through side wall 58 to
provide for the transport of condensate that forms in chamber
59.
[0037] As shown best in FIGS. 5A-5C, all four side walls of the
plenum 44 are constructed with identical panels 61 that can be
selectively removed to orient the plenum 44 in any desired
direction. When a panel 61 is removed, a large opening is formed in
the plenum wall. A panel 61 is removed on one wall to form the
front wall 62 to which hood 66 is attached. The panels 61 and hole
patterns are the same on all four sides of the plenum 44, which
enables complete freedom to place the hood 66 in the desired
orientation.
[0038] A shown best in FIGS. 5D and 5E, the removable panels 61 on
the sides of the plenum 44 also enable multiple plenums 44 to be
combined with a single riser 38. The plenums 44 are mounted
adjacent one another and the panels 61 in their abutting walls are
removed to form a single, enlarged chamber 63. Any number of
plenums 44 may be combined in this manner with complete flexibility
in their orientation. The location of their hoods 66 is provided by
the same removable panels 61 and mounting holes on all four walls
of the plenum 44 in the manner described above.
[0039] The removable panels 61 also enable access to the interior
of the plenum 44 from any direction. This enables routine
maintenance and repairs to be made without having to remove the
entire exhaust assembly 42 from the riser 38 or the fan assembly 46
from the plenum 44.
[0040] Referring to FIGS. 7, 8, and 10 fan assembly 46 sits on top
of the plenum 44 and includes a cylindrical outer wall 100 that is
welded to a rectangular base plate 102. A set of eight gussets 104
is welded around the lower end of the outer wall 100 to help
support it in an upright position. Supported inside the outer wall
100 is a cylindrical shaped inner wall 106 which divides the
chamber formed by the outer wall 100 into three parts: a central
drive chamber 108, a surrounding annular space 110 located between
the inner and outer walls 106 and 100, and a fan chamber 112
located beneath drive chamber 108.
[0041] A fan shaft 114 is disposed in drive chamber 108 and is
rotatably fastened by a bearing 118 to a bottom plate 116 that is
welded to the bottom end of inner wall 106. Fan shaft 114 extends
down into the fan chamber 112 to support a fan wheel 120 at its
lower end, and extends up into drive chamber 108 where it is
connected to a motor shaft 152 via a conventional coupling 122.
Motor shaft 152 extends through a horizontal plate 124 that extends
across the interior of the drive chamber 108 and is supported from
below by a set of gussets 126 spaced around the interior of the
drive chamber 108.
[0042] As best illustrated in FIG. 10, fan wheel 120 includes a
dish-shaped wheelback 130 having a set of main fan blades 132
fastened to its lower surface that support a frustum-shaped rim 136
that extends around the perimeter of the fan blades. The lower edge
of this rim 136 fits around a circular-shaped upper lip of an inlet
cone 138 that fastens to, and extends upward from the base plate
102. The fan wheel 120 is a mixed flow fan wheel such as that sold
commercially by Greenheck Fan Corporation under the trademark MODEL
QEI and described in pending U.S. patent application Ser. No.
10/297,450 which is incorporated herein by reference. When the fan
wheel 120 is rotated, exhaust air from the plenum 44 is drawn
upward through the air inlet formed by the inlet cone 138 and blown
radially outward and upward into the annular space 110 as shown by
arrows 140 (FIG. 11).
[0043] Wheelback 130 can also include, if desired, a set of
auxiliary fan blades 134 fastened to its upper surface that produce
a radially outward directed air flow. Because shaft 114 and lower
bearing 118 should provide a good seal with the bottom plate 116,
no source of air should be available and this air flow is not well
defined. However, if a leak should occur, an air flow pattern is
established in which air is drawn from the drive chamber 108 and
directed radially outward through a gap formed between the upper
rim of the fan wheel 130 and the bottom plate 116. As a result,
exhaust air cannot escape into the drive chamber 108 even if a leak
should occur.
[0044] As best illustrated in FIGS. 7 and 8, access to drive
chamber 108 from outside the fan assembly 46 is provided by two
passageways formed on opposite sides. Each passageway is formed by
aligned elongated openings formed through the outer wall 100 and
inner wall 106 which are connected by a passage wall 144. The
passage wall 144 encircles the passageway and isolates it from the
annular space 110 through which it extends. As shown best in FIG.
11 one can look through either of the passageways and see a fan
drive motor 150 and its associated components, fan shaft 114, and
coupling 122. Maintenance personnel thus have easy access to these
elements for inspection and repair.
[0045] Referring now to FIGS. 7 and 9, and 11, fan drive motor 150
is located in drive chamber 108 and is mounted to horizontal
support plate 124. Specifically, motor 150 is affixed to the upper
surface of a mounting bracket 154, which is fastened to the upper
surface of plate 124 via bolts 156 or like fasteners in order to
provide structural integrity during operation. Mounting bracket 154
includes a flat horizontally extending rectangular plate 160 and a
pair of strengthening flanges 168 extending up from opposing outer
ends of the plate. Flanges 168 extend in a direction substantially
parallel to an axis extending perpendicular between the
passageways.
[0046] Motor shaft 152 extends down through mounting bracket 154,
and is connected directly to the fan shaft 114 via coupling 122
such that motor rotatably drives fan wheel 120 during operation.
When maintenance operations are to be performed on motor 150 or its
associated components inside drive chamber 108, bolts 156 can be
removed, and coupling 122 can be loosened such that motor shaft 152
becomes disengaged from fan shaft 114.
[0047] Advantageously, one edge of mounting bracket 154 is
connected to horizontal plate 124 via a hinge 158 that permits
mounting bracket 154 to pivot relative to horizontal plate 124 once
fastener(s) 156 have been removed. Preferably hinge 158 is oriented
perpendicular to an axis extending perpendicular between through
the passageways. In this regard, hinge extends perpendicular to
flanges 168. Hinge 158 permits mounting bracket 154 and motor 150
to be pivoted between a first position in which shafts 152 and 114
can be engaged by coupling 122 and fasteners 156 can connect
bracket 154 to plate 124, and towards one of the passageways in the
direction of Arrow A to a second position whereby inspection and
maintenance can be performed. Wedge-shaped flanges 168 provide
additional structural support for bracket at locations proximal
hinge 158 where increased forces result from motor pivoting.
[0048] Motor 150 can be manually pivoted about hinge 158 at any
angle between 0.degree. and 180.degree. (with respect to bracket
154 and plate 124) to provide the needed access to the components
inside chamber 18. In one aspect of the invention, motor 150 pivots
at an angle of about 90.degree. such that the vertical surfaces of
flanges 168 proximal hinge 158 provide a stop with respect to motor
150 pivoting beyond 90.degree.. Alternatively, the vertical flange
surfaces could be positioned to provide additional clearance with
respect to plate 124, thereby allowing the motor to pivot beyond
90.degree.. In this instance, a stop in the form of flange 145
could extend from wall 144 (FIG. 9) and protrude a desired distance
to engage upper surface of bracket once motor 150 has pivoted to
the desired angle. Once pivoted, a portion of motor 150 can extend
through one of the passageways while access to components inside
drive chamber 108 can be achieved via the other passageway.
[0049] It should be appreciated that hinge 158 can be disassembled
in the usual manner (e.g., by removing the hinge pin) in order to
facilitate removal of motor 150 from assembly 42.
[0050] Referring also to FIG. 8, the exhaust air moves up through
the annular space 110 and exits through an annular-shaped nozzle
162 formed at the upper ends of walls 100 and 106 as indicated by
arrows 164. The nozzle 162 is formed by flaring the upper end 166
of inner wall 106 such that the cross-sectional area of the nozzle
162 is substantially less than the cross-sectional area of the
annular space 110. As a result, exhaust gas velocity is
significantly increased as it exits through the nozzle 162. As
shown best in FIGS. 11 and 13, vanes 170 are mounted in the annular
space 110 around its circumference to straighten the path of the
exhaust air as it leaves the fan and travels upward. The action of
vanes 170 has been found to increase the entrainment of ambient air
into the exhaust as will be described further below.
[0051] Referring particularly to FIGS. 8 and 11, a windband 52 is
mounted on the top of fan assembly 46 and around nozzle 162. A set
of brackets 54 is attached around the perimeter of the outer wall
100. Brackets 54 extend upward and radially outward from the top
rim of outer wall 100, and fasten to the windband 52. Windband 52
is essentially frustum-shaped with a large circular bottom opening
coaxially aligned with the annular nozzle 162 about a central axis
56. The bottom end of the windband 52 is flared by an inlet bell 58
and the bottom rim of the inlet bell 58 is aligned substantially
coplanar with the rim of the nozzle 162. The top end of the
windband 52 is terminated by a circular cylindrical ring section 60
that defines the exhaust outlet of the exhaust assembly 42.
[0052] Referring particularly to FIG. 11, the windband 52 is
dimensioned and positioned relative to the nozzle 162 to entrain a
maximum amount of ambient air into the exhaust air exiting the
nozzle 162. The ambient air enters through an annular gap formed
between the nozzle 162 and the inlet bell 58 as indicated by arrows
62. It mixes with the swirling, high velocity exhaust exiting
through nozzle 162, and the mixture is expelled through the exhaust
outlet at the top of the windband 52.
[0053] A number of features on this system serve to enhance the
entrainment of ambient air and improve fan efficiency. The flared
inlet bell 58 at the bottom of the windband 52 has been found to
increase ambient air entrainment by several percent. This
improvement in air entrainment is relatively insensitive to the
angle of the flare and to the size of the inlet bell 58. The same
is true of the ring section 60 at the top of the windband 52. In
addition to any improvement the ring section 60 may provide by
increasing the axial height of the windband 52, it has been found
to increase ambient air entrainment by 5% to 8%. Testing has shown
that minor changes in its length do not significantly alter this
performance enhancement.
[0054] It has been discovered that ambient air entrainment is
maximized by minimizing the overlap between the rim of the nozzle
162 and the bottom rim of the windband 52. In the preferred
embodiment these rims are aligned substantially coplanar with each
other such that there is no overlap.
[0055] Another feature which significantly improves fan system
operation is the shape of the nozzle 162. It is common practice in
this art to shape the nozzle such that the exhaust is directed
radially inward to "focus" along the central axis 56. This can be
achieved by tapering the outer wall radially inward or by tapering
both the inner and outer walls radially inward to direct the
exhaust towards the central axis 56. It is a discovery of the
present invention that ambient air entrainment can be increased and
pressure losses decreased by shaping the nozzle 162 such that
exhaust air is directed radially outward rather than radially
inward towards the central axis 56. In the preferred embodiment
this is achieved by flaring the top end 166 of the inner wall 106.
Air entrainment is increased by several percent and pressure loss
can be reduced up to 30% with this structure. It is believed the
increase in air entrainment is due to the larger nozzle perimeter
that results from not tapering the outer wall 100 radially inward.
It is believed that the reduced pressure loss is due to the fact
that most of the upward exhaust flow through the annular space 110
is near the outer wall 100 and that by keeping this outer wall 100
straight, less exhaust air is diverted, or changed in direction by
the nozzle 162.
[0056] Referring particularly to FIG. 7, ambient air is also drawn
in through the passageways and mixed with the exhaust air as
indicated by arrows 170. This ambient air flows out the open top of
the flared inner wall 100 and mixes with the exhaust emanating from
the surrounding nozzle 162. The ambient air is thus mixed from the
inside of the exhaust.
[0057] As shown in FIGS. 7, 8, 11 and 12, to protect the fan drive
elements in the drive chamber 108 from the elements, a sloped roof
172 is formed above the top end of the fan shaft 114. The roof 172
seals off the drive chamber 108 from the open top end of the inner
wall 106, and it is sloped such that rain will drain out the
passageways. The slope of roof 172 also provides additional
clearance to enable unobstructed pivoting of motor 150. In another
aspect of the invention, roof 172 can be eliminated to more easily
facilitate the removal of motor 150 from assembly 42, which can be
easily achieved by lifting motor 150 up through windband 52.
[0058] In addition to the performance enhancements discussed above,
the structure of the exhaust assembly lends itself to customization
to meet the specific needs of users. Such user specifications
include volume of exhaust air, plume height, amount of dilution
with ambient air, and assembly height above roof top. User
objectives include minimizing cost. Such customization is achieved
by selecting the size, or horsepower, of the fan motor 150, and by
changing the four system parameters illustrated in FIG. 15.
[0059] Nozzle Exit Area:
[0060] Increasing this parameter decreases required motor HP,
decreases ambient air entrainment, decreases plume rise. Decreasing
this parameter increases required motor HP, increases ambient air
entrainment, increases plume rise.
[0061] Windband Exit Area:
[0062] Increasing this parameter increases ambient air entrainment,
does not significantly affect plume rise or fan flow. Decreasing
this parameter decreases ambient air entrainment, does not
significantly affect plume rise or fan flow.
[0063] Windband Length:
[0064] Increasing this parameter increases ambient air entrainment,
increases plume rise, does not affect fan flow. Decreasing this
parameter decreases ambient air entrainment, decreases plume rise,
does not affect fan flow.
[0065] Windband Entry Area (Minor Effect)
[0066] Increasing this parameter increases ambient air entrainment,
increases plume rise, does not affect fan flow. Decreasing this
parameter decreases ambient air entrainment, decreases plume rise,
does not affect fan flow.
[0067] For example, for a specified system, Table 1 illustrates how
windband length changes the amount of entrained ambient air in the
exhaust and Table 2 illustrates how windband exit diameter changes
the amount of ambient air entrainment.
1 TABLE 1 Windband Length Dilution 39 inch 176% 49 inch 184% 59
inch 190%
[0068]
2 TABLE 2 Windband Exit Diameter Dilution 17 inch 165% 21 inch 220%
25 inch 275%
[0069] Table 3 illustrates how the amount of entrained ambient and
changes as a finction of nozzle exit area and Table 4 illustrates
the relationship between the amount of entrained ambient air and
windband entry area.
3 TABLE 3 Nozzle Exit Area Dilution .79 ft.sup.2 120% .52 ft.sup.2
140% .43 ft.sup.2 165%
[0070]
4 TABLE 4 Windband Entry Area Dilution 10.3 ft.sup.2 176% 12.9
ft.sup.2 178%
[0071] In Tables 1-4 the dilution is calculated by dividing the
windband exit flow by the flow through the fan assembly.
[0072] Referring particularly to FIGS. 16 and 17, an alternative
embodiment of the invention is substantially the same as the
preferred embodiment described above except the nozzle end of the
fan assembly 46 is modified to add an additional, second nozzle
assembly 50. In this second embodiment the outer wall 100 of the
fan assembly is tapered radially inward at its upper end to form a
first nozzle 53 with the inner wall 106 which extends straight
upward, beyond the nozzle 53. The second nozzle assembly 50 is a
frustum-shaped element which is fastened to the extended portion of
the inner wall 106 by brackets 55. It is flared around its bottom
end to form an inlet bell 57 similar to that on the windband 52.
The second nozzle assembly 50 is concentric about the inner wall
106, and its top end is coplanar with the top end of the inner wall
106 to form an annular-shaped second nozzle 59 therebetween.
Brackets 61 fasten around the perimeter of the second nozzle
assembly 50 and extend upward and radially outward to support the
windband 52. The windband 52 is also aligned coaxial with the inner
wall 106 and second nozzle assembly 50 and its lower end is
substantially coplanar with the top end of the second nozzle 59. In
this alternative embodiment it is also possible to form the first
nozzle 53 by flaring the inner wall 106 outward rather than
tapering the outer wall 100.
[0073] Referring particularly to FIG. 17, the annular space between
the lower end of the second nozzle assembly 50 and the outer wall
100 forms a first gap through which ambient air enters as indicated
by arrows 63. This air is entrained with the swirling exhaust air
exiting the first nozzle 53 to dilute it. Similarly, the annular
space between the lower end of the windband 52 and the second
nozzle assembly 50 forms a second gap through which ambient air
enters as indicated by arrows 65. This air is entrained with the
once diluted exhaust air exiting the second nozzle 59 to further
dilute the exhaust. As with the first embodiment, further ambient
air which enters through the passageways and flows out the top end
of the inner wall 106 as shown in FIG. 16 by arrow 67 also dilutes
the exhaust before it is expelled at high velocity out the exhaust
outlet at the top of the windband 52.
[0074] The above description has been that of the preferred
embodiment of the present invention, and it will occur to those
having ordinary skill in the art that many modifications may be
made without departing from the spirit and scope of the invention.
In order to apprise the public of the various embodiments that may
fall in the scope of the present invention, the following claims
are made.
* * * * *