U.S. patent application number 11/552391 was filed with the patent office on 2007-04-26 for linear drive for integrated damper.
Invention is credited to Mark Huza, Thomas C. Morse.
Application Number | 20070093196 11/552391 |
Document ID | / |
Family ID | 37968150 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070093196 |
Kind Code |
A1 |
Morse; Thomas C. ; et
al. |
April 26, 2007 |
LINEAR DRIVE FOR INTEGRATED DAMPER
Abstract
A housing assembly having an integrated damper with a linear
drive mechanism is provided. In one embodiment, the housing
assembly includes a housing having an inlet and an outlet. A damper
is disposed in the housing and is positionable to regulate flow
entering the housing through the inlet. A linear drive mechanism is
operably coupled to the damper and is adapted to linearly move the
damper between positions that are spaced-apart from the housing and
a position that closes the inlet. The linear drive mechanism is
configured to move the damper linearly without rotating the
damper.
Inventors: |
Morse; Thomas C.;
(Greenville, NC) ; Huza; Mark; (Columbia,
MD) |
Correspondence
Address: |
PATTERSON & SHERIDAN L.L.P.
595 SHREWSBURY AVE, STE 100
FIRST FLOOR
SHREWSBURY
NJ
07702
US
|
Family ID: |
37968150 |
Appl. No.: |
11/552391 |
Filed: |
October 24, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60729644 |
Oct 24, 2005 |
|
|
|
Current U.S.
Class: |
454/290 |
Current CPC
Class: |
F16K 31/54 20130101;
F24F 2013/1446 20130101; F24F 13/10 20130101; F16K 1/38
20130101 |
Class at
Publication: |
454/290 |
International
Class: |
F24F 13/08 20060101
F24F013/08 |
Claims
1. A housing assembly, comprising: a housing having an inlet and an
outlet; a damper disposed in the housing in an orientation that
remains centered with respect to the inlet; and a linear drive
mechanism adapted to move the damper linearly between positions
that open and close the inlet without rotating the damper.
2. The housing assembly of claim 1, wherein the damper is
substantially conical.
3. The housing assembly of claim 1 further comprising: a filter
element disposed in the housing.
4. The housing assembly of claim 1, wherein the housing is at least
one of a filter housing, a contamination housing or a stand-alone
damper.
5. The housing assembly of claim 1, wherein the linear drive
mechanism is at least one of a cam, a scissor actuator, a linear
actuator, a power screw, a solenoid, an electric motor, a pneumatic
cylinder, a hydraulic cylinder or a gear.
6. The housing assembly of claim 1 further comprising: a seal
interfacing the damper and the housing to providing a bubble-tight
seal of the inlet when the damper is in the closed position.
7. The housing assembly of claim 1 further comprising: a seal
coupled to a perimeter of the damper and adapted to sealingly
engage the housing to providing a bubble-tight seal of the inlet
when the damper is in the closed position.
8. The housing assembly of claim 1, wherein the seal further
comprise: at least one of a gasket, fluid seal or a bladder.
9. The housing assembly of claim 1, wherein the linear drive
mechanism further comprises: a shaft coupled to the damper engaged
with a feature that prevents rotation of the damper when the shaft
is moved in a linear direction.
10. A housing assembly, comprising: a housing having an inlet and
outlet; a damper disposed in the housing and linearly movable
between positions that open and close the inlet, the damper having
a non-planar shape that extends into the inlet when the damper is
in the closed position; and means for restraining the damper from
rotating.
11. The housing assembly of claim 10, wherein the means for
restraining further comprises: a first feature coupled to the
housing and fixed in orientation relative to the housing; and a
second feature fixed in orientation relative to the damper, wherein
the second feature engages the first feature in a manner that
permits linear motion without rotation.
12. The housing assembly of claim 10, wherein the means for
restraining further comprises: mating threaded members having
truncated crests and valleys.
13. The housing assembly of claim 10, wherein the means for
restraining further comprises: a shaft coupled to the damper, the
shaft having a non-circular cross section; and a bearing or guide
circumscribing the shaft, the bearing or guide having a shaft
accepting aperture mating the shape of the shaft.
14. A housing assembly, comprising: a housing having an inlet port,
an outlet port and a bag in/bag out filter access port; a filter
receiving mechanism disposed in the housing, the filter receiving
mechanism configured to direct gases flowing between the inlet and
outlet ports through a filter installed in the housing; a first
damper disposed in the housing and movable between positions that
open and close the inlet port; a second damper disposed in the
housing and movable between positions that open and close the
outlet port; a mechanism disposed in the housing and configured to
move the first damper between the open and closed positions without
rotating the first damper, wherein the first damper is spaced apart
from the housing when in the open position.
15. The housing assembly of claim 14, wherein the damper is
substantially conical.
16. The housing assembly of claim 14, wherein the mechanism is at
least one of a cam, a scissor actuator, a linear actuator, a power
screw, a solenoid, an electric motor, a pneumatic cylinder, a
hydraulic cylinder or a gear.
17. The housing assembly of claim 14 further comprising: a seal
interfacing the first damper and the housing to providing a
bubble-tight seal of the inlet when the first damper is in the
closed position.
18. The housing assembly of claim 14 further comprising: a seal
coupled to a perimeter of the first damper and adapted to sealingly
engage the housing to providing a bubble-tight seal of the inlet
when the first damper is in the closed position.
19. The housing assembly of claim 18, wherein the seal further
comprise: at least one of a gasket, fluid seal or a bladder.
20. The housing assembly of claim 14, wherein the mechanism further
comprises: a shaft coupled to the damper engaged with a feature
that prevents rotation of the damper when the shaft is moved in a
linear direction.
21. The housing assembly of claim 14, the first damper has a
non-planar shape that extends into the inlet when the first damper
is in the closed position.
Description
[0001] This application claims benefit from U.S. Provisional Patent
Application Ser. No. 60/729,644, filed Oct. 24, 2005, which is
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a housing
assembly having an integrated damper, and more specifically, a
housing assembly for an air filter having an integrated damper with
a linear drive mechanism.
[0004] 2. Description of the Related Art
[0005] Cleanrooms are utilized in many industries for contamination
control and to improve product yields. A plurality of filters,
typically mounted in the ceiling of the cleanroom, are configured
to remove particulate from air entering the cleanroom at a
predetermined efficiency selected based upon the cleanliness
requirements of the activities performed in the cleanroom. As
particulates load the filtration media disposed in the filter, the
airflow through the filter decreases as the pressure drop across
the filter increases. Once the filter reaches a critical pressure
drop, the filter is typically replaced.
[0006] On other applications, replacement of filters is scheduled
based on time or processes performed within the cleanroom. For
example, in many pharmaceutical and biotech cleanrooms, periodic
replacement of filters is required to meet regulatory or owner
specifications. To facilitate efficient replacement of the filter,
a hood (housing) is typically mounted in the cleanroom ceiling in
which the filter may be readily removed and replaced.
[0007] Ducted supply hoods with roomside replaceable filters are
commonly used in pharmaceutical applications for cleaning supply
air to cleanroom manufacturing and process areas, as well as to
laboratory areas. Most of these hoods are supplied with adjustable
dampers that allow customers to regulate the airflow without having
to remove the filter from the hood. The most common types of
dampers are guillotine, opposed blade and butterfly types. When
completely closed, these dampers essentially stop the flow of air
to the hood. In many cases, the leakage through a closed damper is
negligible in terms of flow rate, but is significant when
considered in the terms of contamination of a cleanroom.
[0008] Because these types of dampers do not provide a seal (i.e.,
are not leak-free or bubble-tight), they are inadequate when it
comes to decontamination processes that require complete isolation
of the cleanroom. For example, during routine testing and
validation of filters installed in a pharmaceutical facility, one
or more filters may be found damaged, leaking and/or requiring
replacement. When a technician removes that filter from the hood,
the "seal" between the cleanroom and the contaminated plenum and
supply ducts upstream of the removed filter is broken. When the new
filter is installed, the "seal" between those two areas is
restored, but the cleanroom has already been contaminated by air
and particulate entering the cleanroom from the contaminated area
of the plenum and supply ducts. Thus, the facility owner must
perform a decontamination process of the entire room before
resuming cleanroom operations. This is a very time-consuming and
costly process.
[0009] Therefore, there is a need for a filter housing assembly
having improved sealing capabilities.
SUMMARY OF THE INVENTION
[0010] Embodiments of the invention generally include a housing
assembly having an integrated damper with a linear drive mechanism.
In one embodiment, a housing assembly includes a housing having an
inlet and an outlet. A damper is disposed in the housing and is
positionable to regulate flow entering the housing through the
inlet. A linear drive mechanism is operably coupled to the damper
and is adapted to linearly move the damper between positions that
are spaced-apart from the housing and a position that closes the
inlet. The linear drive mechanism is configured to move the damper
linearly without rotating the damper.
[0011] In another embodiment, a housing assembly includes a housing
having an inlet and outlet. A damper is disposed in the housing and
is linearly movable between positions that open and close the
inlet. The damper has a non-planar shape that extends into the
inlet when the damper is in a closed position. A means is provided
for restraining the damper from rotating.
[0012] In another embodiment, a housing assembly includes an inlet
port, an outlet port and a bag in/bag out filter access port. A
filter receiving mechanism is disposed in the housing and is
configured to direct gases flowing between the inlet and outlet
ports through a filter installed in the housing. A first damper is
disposed in the housing and is movable between positions that open
and close the inlet port. A second damper is also disposed in the
housing and is movable between positions that open and close the
outlet port. A mechanism is provided in the housing that is
configured to move the first damper between the open and closed
positions without rotating the first damper, wherein the first
damper is spaced apart from the housing when in the open
position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The teachings of the present invention can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0014] FIG. 1 is a cross-sectional view of one embodiment of a
linear damper assembly disposed in a filter housing assembly;
[0015] FIG. 2 is a partial sectional view of the housing assembly
of FIG. 1;
[0016] FIG. 3 is a top view of a portion of an actuator adapted for
linearly moving a dish of the damper assembly;
[0017] FIG. 4 is a side view of a bushing;
[0018] FIG. 5 is a partial side view of a rack of the actuator;
[0019] FIG. 6 is a side cut-away view of one embodiment of a linear
damper assembly disposed in a contamination housing assembly;
[0020] FIG. 7 is another embodiment of a linear damper assembly
disposed in a housing assembly;
[0021] FIG. 8 is a perspective view of one embodiment of the linear
damper assembly in an open position; and
[0022] FIG. 9 is a perspective view of the linear damper assembly
in a closed position.
[0023] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
and features of one embodiment may be beneficially incorporated in
other embodiments without further recitation.
[0024] It is to be noted, however, that the appended drawings
illustrate only exemplary embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
DETAILED DESCRIPTION
Selected Embodiments of the Apparatus
[0025] FIG. 1 is a sectional view of one embodiment of a filter
housing assembly 100 having a linear damper assembly 130. Although
the housing assembly 100 is depicted in FIG. 1 as a room-side
replaceable filter module, it is contemplated that the benefits and
features of the invention may be incorporated in contamination
housings, filter diffusers, damper modules and other devices where
robust flow control is desired in applications for cleanrooms,
environmental and contaminant control, air conditioning, heating
and ventilation systems, among other applications.
[0026] The housing assembly 100 generally includes a housing 102
having an inlet 104 and an outlet 106. The inlet 104 and the outlet
106 are formed through the housing 102 and allow gases flowing
through a duct 110, shown in phantom, to be routed through the
housing 102. The inlet 104 is bounded by a collar 112 to facilitate
coupling the duct 110 to the housing 102. A filter element 108 is
disposed in the outlet 106 and is sealingly coupled to the housing
102 in a manner that causes gases flowing between the inlet 104 and
the outlet 106 to pass through the filter element 108. The filter
element 108 may be retained in the housing 102 in any suitable
manner, for example by a clip 120 or fastener.
[0027] In the embodiment depicted in FIG. 1, the housing 102
includes an internal flange 114 that sealingly engages the filter
element 108. In one embodiment, the flange 114 includes a
knife-edge 116 that sealingly engages a seal 118 coupled to the
filter element 108. The seal 118 may alternatively be coupled to
the housing 102. The seal 118 may be a fluid seal, such as a gel, a
gas gasket or other material suitable for providing a seal between
the housing 102 and filter element 108. It is also contemplated, as
in diffuser applications, that the filter element 108 may be
potted, bonded, adhered or permanently coupled to the housing
102.
[0028] The damper assembly 130 is disposed in the housing 102
between the inlet 104 and the filter element 108. The damper
assembly 130 generally includes a damper dish 132, a linear drive
mechanism 136 and a bracket 144. The bracket 144 is coupled to the
housing 102. The bracket 144 generally supports and positions the
dish 132 and linear drive mechanism 136 within the housing 102. The
linear drive mechanism 136 is configured to move the dish 132
linearly to open and close the inlet 104.
[0029] Referring back to FIG. 1, the linear drive mechanism 136 may
be any actuator suitable for causing the dish 132 to move linearly
without rotation. For example, linear drive mechanism 136 may be a
power screw, solenoid, electric motor, pneumatic cylinder,
hydraulic cylinder or cam, scissor actuator, linear actuator among
others. In the embodiment depicted in FIG. 1, the actuator 138
includes a rack 138 and a gear 140. The rack 138 is coupled to a
dish 132 by a fastener 134. It is contemplated that the dish 132
may be coupled to the rack 138 by other suitable fastening methods.
To insure a perpendicular orientation between the dish 132 and the
rack 138, the dish 132 includes a flat center section 162 that
seats against the flat end of the rack 138.
[0030] In the embodiment depicted in FIG. 1, the gear 140 is a
pinion gear, although another gear or gears may be utilized. The
pinion gear 140 is coupled to a shaft 152. The size of the pinion
gear 140 may be selected to provide a predetermined stroke of the
rack 138, and to provide a predetermined actuation force. In one
embodiment, the shaft 152 extends through the housing 102 such that
the rotational orientation of the pinion gear 140, and thus, the
position of the rack 138 and dish 132, may be controlled. The shaft
152 may include a key or other suitable connection with the pinion
gear 140 that insures efficient transfer of motion between the
shaft 152 and pinion gear 140. In one embodiment, the intermeshing
teeth of the rack 138 and pinion gear 140 include flat crests and
trenches that prevent the dish 132 from rotating as the rack 138 is
advanced. The flat crests and trenches of the rack 138 are
illustrated in FIG. 5, with the pinion gear 140 being similarly
configured. It is contemplated that the linear drive mechanism may
have other configurations that prevent rotation of the dish 132,
including, but not limited to, keyed retaining features, tracks,
multiple bearing guides, and the like.
[0031] The rack 138 is slidably mounted through a set of bushings
142 that are coupled to the bracket 144. The bushings 142 may be
comprised of any suitable bearing material, such as DELRIN.RTM. or
brass. The bushings 142 may alternatively be roller bearings. The
rack 138 may be exchanged to provide longer or short actuation
strokes which correspondingly sets the orifice area between the
dish 132 and the inlet 104.
[0032] In the embodiment depicted in FIG. 1, the bracket 144
includes a rack support 146 having two tabs 148 extending
therefrom. The bushings 142 are mounted in the tabs 148 in a
spaced-apart relation to enhance control of the motion and
orientation of the dish 132. The rack support 146 is coupled to one
or more cross bars 150 extending between opposite walls of the
housing 102. The cross bars 150 may be welded, riveted or fastened
to the housing 102.
[0033] The dish 132 generally includes a conical face 160 having a
sealing section 164 located adjacent a perimeter 166 of the dish
132. The sealing section 164 is adapted to engage the housing 102
and/or the collar 112 in a manner that facilitates sealing the air
flow through the inlet 104. In the embodiment depicted in FIG. 1,
the sealing section 164 includes a channel 168 having a seal 170
disposed therein. The seal 170 is configured to engage with a lip
172 extending from one of the collar 112 or the housing 102. The
seal 170 may be a gasket, bladder or fluid seal. It is also
contemplated that the seal 170 may be coupled to the collar 112 or
the housing 102 and configured to sealingly engage with the dish
132. The non-rotation of the dish 132 provided by the rack 138 and
pinion gear 140 discussed above, prevents shearing of the seal as
the dish 132 and lip 170 engage, thereby extending the life and
performance of the seal. It is contemplated that the dish 132 may
rotate when spaced from the closed position, as long as the linear
drive mechanism 136 does not cause the dish 132 to rotate while
sealing the inlet 104.
[0034] FIG. 2 depicts a partial sectional view of the housing 102
illustrating the shaft 152 extending through the housing 102. To
prevent leakage from the housing assembly 100 around the shaft 152,
a bushing 202 is sealably fastened around a hole 204 formed through
the housing 102 to facilitate passage of the shaft 152. The bushing
202 may be sealed to the housing 102 by any suitable method. In the
embodiment depicted in FIG. 2, the bushing 202 is continuously
welded to the housing 102.
[0035] A bearing 206 is press-fit into the bushing 202 and engages
the shaft 152 to facilitate rotation. A seal 208 is disposed in one
end of the bushing 202 to prevent air leakage between the bushing
202 and the shaft 152. The seal 208 may be an o-ring, cup seal,
gasket, fluid seal or other seal suitable for preventing leakage of
gas around the shaft 152 and through the hole 204 of the housing
102.
[0036] The shaft 152 includes terminal end 250 disposed outside the
housing assembly 100. The terminal end 250 generally includes a
drive feature 252 that facilitates inducing rotational motion to
the shaft 152. In one embodiment, the drive feature 252 is a flat
formed in the sides of the shaft 152. Other suitable drive features
include, but are not limited to, hex heads, knurled surface, key
ways, slots and the like. Although the terminal end 250 is shown
extending from the side of the housing 102, it is contemplated that
the drive feature 252 may be accessible from the other locations,
such as from the outlet-side of the housing 100.
[0037] Referring to FIGS. 3-4, the inner end of the shaft 152
proximate the pinion gear 140 is supported by a second bearing 304.
The second bearing 304 is disposed in a tab 302 extending from the
rack support 146. The second bearing 304 may be similar to the
bearing 206.
[0038] In operation, the shaft 152 is selectively rotated to rotate
the pinion gear 140. The rotating pinion gear 140 advances the rack
138, thereby linearly moving the dish 132. As the motion of the
dish 132 is substantially perpendicular to the plane of the opening
defined by the inlet 104, the seal 170 uniformly engages the lip
172, thereby enhancing seal uniformity and performance. Moreover,
as the dish 132 is maintained centered relative to the flow
entering (or exiting) the housing 102 through the inlet 104, the
flow orifice defined between the dish 132 and lip 172 is uniform,
thus, promoting flow uniformity through the filter element 108. The
dish 132 is illustratively shown in a position closing and spaced
from the inlet 104 in FIGS. 8-9. The spacing of the dish 132 from
the lip 172 may be selected to provide a desired air flow rate
through the filter element 108.
[0039] FIG. 6 is a sectional view of one embodiment of a
contamination housing assembly 600. A contamination housing
assembly that may be adapted to benefit from the invention is
available from Camfil Farr, Inc., located in Riverdale, N.J.
[0040] In one embodiment, the housing assembly 600 includes a
housing 602 having an inlet 604, an outlet 606 and at least one
access port 608. The inlet 604 and outlet 606 are formed through
the housing 602 and arrange to direct gases flowing through the
housing 602. The access port 608 is configured to permit access to
the interior of the housing 602, for example, for filter
change-out, scanning a filter disposed in an adjacently coupled
housing, and the like.
[0041] The housing 602 may be fabricated from a metal, such as
aluminum, steel and stainless steel, or other suitable material.
The housing 602 has a construction that forms a pressure barrier
between gases flowing therethrough and an environment outside the
housing 602. In the embodiment depicted in FIG. 6, the housing 602
is a hollow rectangular body fabricated from continuously welded
metal sheets.
[0042] The housing 602 additionally includes sealing flange 614
that sealingly engages a filter element 616 disposed in the housing
assembly 600. A linkage mechanism 620 is provided in the housing
602 and is configured to move the filter element 616 between a
position sealingly engaged with the flange 614 and a position clear
of the flange 614. A seal, not shown, like the seal 170 described
above, is disposed between the filter element 616 and flange 164 to
prevent flow from bypassing the filter element 616.
[0043] The access port 608 is configured to facilitate removal of
the filter element 616 from the housing 602 and is selectively
sealed by a door 622. The access port 608 is circumscribed by a
bagging ring (not shown) that is utilized to access the interior of
the housing and/or remove and replace the filter element 616.
[0044] At least one end of the contamination housing 600 includes a
linear damper assembly 130. The linear damper assembly 130 is as
described above. In the embodiment depicted in FIG. 6, an external
actuator 690 is coupled to the shaft 152 of the damper assembly 130
on the exterior of the housing 602. The external actuator 690 may
be any device or object suitable for controlling the rotation of
the shaft 152. In one embodiment, the external actuator 690 is a
wheel. It is contemplated that the external actuator 690 may
alternatively be a motor, pneumatic cylinder, hydraulic cylinder or
a lever, among others.
[0045] FIG. 7 depicts one embodiment of a housing assembly 700
having a damper assembly 130. The housing 700 may be configured
with or without an access port 608. The housing assembly 700 may be
utilized as a stand-alone damper (shutoff and/or flow control), or
as an access port in a containment system, among others. The damper
assembly 130 may be operated as described with reference to the
embodiments above to control flow through the housing assembly
700.
Life Cycle Testing
[0046] A housing assembly having an integrated linear damper
assembly as described above was tested to determine if any
significant or adverse amount of wear will occur between the
fabricated pinion gear and rack (both fabricated from stainless
steel); and if any significant or adverse amount of wear will occur
in the bronze bushings used to support the rack and the damper
shaft.
Test Setup
[0047] A one-high by one-wide containment housing was modified to
accept the integrated linear damper assembly. The integrated damper
assembly utilized a 12'' diameter stainless steel dish. A medium
durometer silicone sponge gasket was cut by hand using a template.
RTV was placed in the bottom of the channel of the dish. The gasket
was seated in the channel, using the RTV as an adhesive to hold the
gasket in the channel. The edges of the sponge gasket were not
sealed in the channel, in order to test the seal with minimum
adhesion to the dish.
[0048] The damper actuator included a three quarter inch diameter
stainless steel shaft with keyway, which is typically used on
conventional flat blade dampers. A pinion gear was fabricated from
one quarter inch thick 304 stainless steel. Three gear pieces were
stacked on top of each other with the keyways aligned and welded
together to form a single gear about three quarter inch thick. The
rack was manufactured from 20 mm diameter, 304 stainless steel
shaft. The rack travels in a linear fashion and was held in place
and aligned using bronze bushings coupled to the bracket. A bronze
bushing was also installed in a support member to hold and align
the damper shaft and assure proper meshing of the gear teeth with
the rack.
[0049] A lip extending from a 12 inch (304.8 mm) diameter, 304
stainless steel collar circumscribing the inlet was used to form
that knife-edge circumscribing the inlet. The collar was
continuously welded to a piece of 11 gauge 304 stainless steel that
was continuously welded to the upstream flange of the housing.
[0050] As an actuator coupled to the damper assembly rotated to
turn the pinion gear, the rack is advanced linearly toward the
inlet. The rack pushes the stainless steel dish toward the
knife-edge mounted in the endplate of the housing. The silicone
gasket around the perimeter of the dish sealed against the
knife-edge. In one embodiment, the flat form of the teeth of the
rack, engaged with the flat form of the teeth of the shaft
substantially prevents rotation of the shaft.
Test Equipment & Instrumentation
[0051] Elomatic 350 Series Pneumatic Actuator with spring return
[0052] Model: ESO350.U2A03B.27K0 [0053] Serial No.: 22221100020
[0054] Blank-off Plate with Ball Valve and static pressure
connection [0055] OMRON Timer: [0056] Model: H3CR-F8300 [0057]
Dwyer Flex-Tube Manometer: [0058] Gast Vacuum Pump Test
Procedure
[0059] The damper was bubble-tested in accordance with CFW-1000
CFW-10003, Revision 3: Pressure Decay/Structural Capability/Bubble
Leak Testing. The containment housing with integrated damper was
placed on a cart and a blank-off plate with ball valve and static
pressure port was attached to the opposite end of the inlet collar
that also serves as the knife-edge. This space was pressurized such
that the damper was being pushed away from the knife-edge. The
pressure was measured with a U-tube manometer that provided a
differential pressure reading between the pressurized space and
atmospheric pressure. Soap solution was sprayed on the interface
between the knife-edge on the inlet ring and the silicone gasket
that it was sealing against. Visual inspections were conducted for
a period of 5 minutes to ensure bubble-tightness (i.e., a leak free
condition).
[0060] Generally, bubble-tight dampers are bubble-leak tested at
>+10'' water gauge (w.g.) (2.50 kPa). In some circumstances,
they are required to be bubble-tight at >+15'' w.g. (3.74 kPa).
During this test, the linear damper was tested at >+18'' w.g.
(4.48 kPa).
[0061] After the initial bubble-test, power and compressed air were
supplied to the actuator, and the damper was cycled between open
and closed positions. Bubble-tests were conducted after more than
5,000, 10,000 and 15,000 cycles using the method described above.
Visual observations were conducted throughout the entire test to
determine the effect of rapid repeated cycling on the durability of
the seal and actuation mechanism.
Results
[0062] The results of the cycle tests are as follows:
TABLE-US-00001 TABLE 1 Cycle Test Results Cumulative # of Cycles
Pressure Pass or Fail Comments 0 >17'' w.g. Pass Initial Test
(4.23 kPa) 5585 >28'' w.g. Pass Damper was left closed the (6.97
kPa) previous night. Indentation in silicone gasket, but still
passed the bubble-tight test. No indication of mechanism wear.
10,289 >+18'' w.g. Pass Damper was left closed the (4.48 kPa)
previous night. Indentation in silicone gasket, but still passed
the bubble-tight test. No indication of mechanism wear. 15,260
>+18'' w.g. Pass Damper was left closed the (4.48 kPa) previous
night. Indentation in silicone gasket, but still passed the
bubble-tight test. No indication of mechanism wear.
[0063] As shown in Table 1, the damper was bubble-tight at
>+18'' w.g. (4.48 kPa) for each test conducted. It is believed
that the damper would remain bubble-tight at higher pressures. The
test was terminated after 15,260 cycles without failure to
facilitate use of the lab for other projects. Upon visual
observation and inspection of the mechanism for damper actuation
after conclusion of the test, no evidence of mechanism wear,
degradation or failure was apparent. There also was no visual
evidence of gear wear.
[0064] The tested damper assembly compares favorably to
conventional flat-blade dampers and dish-style dampers. The
extended life is believed attributable to the design and
construction of the damper assembly, which utilizes linear motion
that has reduce bushing wear and stress compared to rotating blade.
Moreover, the linear motion and the use of gearing reduces the
power required to close the damper, thereby minimizing actuator
costs.
CONCLUSIONS
[0065] The damper was proven to remain bubble-tight at >+18''
w.g. (4.48 kPa) at more than 15,000 cycles, which is 50 percent
greater than the industry requirements (bubble-tight at +10'' w.g.
(2.50 kPa) after 10,000 cycles). The robustness and durability of
the mechanism are superior to both the flat-blade damper and
dish-style damper designs, as proven by the lack of wear even after
more than 15,000 cycles.
[0066] Although various embodiments which incorporate the teachings
of the present invention have been shown and described in detail
herein, those skilled in the art can readily devise many other
varied embodiment that still incorporate these teachings.
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