U.S. patent application number 14/623385 was filed with the patent office on 2015-06-11 for barometric relief air zone damper.
This patent application is currently assigned to Controlled Holdings, LLC. The applicant listed for this patent is Controlled Holdings, LLC. Invention is credited to Ronald E. Jackson.
Application Number | 20150159906 14/623385 |
Document ID | / |
Family ID | 48572400 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150159906 |
Kind Code |
A1 |
Jackson; Ronald E. |
June 11, 2015 |
BAROMETRIC RELIEF AIR ZONE DAMPER
Abstract
A zone damper having a first portion controlled by a actuator to
move between an open and a closed position in response to a zone
thermostat, a second portion responsive to the static pressure in a
HVAC system to open and bleed an amount of conditioned air past the
damper when the static pressure of the system increases above a
selected level, a coupling mechanism coupling the first and second
portions to limit the relative movements of the two portions with
respect to each other, and a biasing mechanism exerting a torque
against the system static pressure differential.
Inventors: |
Jackson; Ronald E.;
(Indianapolis, IN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Controlled Holdings, LLC |
Indianapolis |
IN |
US |
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Assignee: |
Controlled Holdings, LLC
|
Family ID: |
48572400 |
Appl. No.: |
14/623385 |
Filed: |
February 16, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13562859 |
Jul 31, 2012 |
8956207 |
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14623385 |
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13463952 |
May 4, 2012 |
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13562859 |
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61569845 |
Dec 13, 2011 |
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Current U.S.
Class: |
454/255 ;
165/217; 165/219 |
Current CPC
Class: |
F24F 13/1426 20130101;
F24F 11/74 20180101; F24F 13/24 20130101; F24F 11/76 20180101; Y10T
137/0352 20150401 |
International
Class: |
F24F 11/04 20060101
F24F011/04; F24F 13/24 20060101 F24F013/24; F24F 11/053 20060101
F24F011/053 |
Claims
1. A method of operating a zone damper comprising: activating an
actuator to position a mechanical blade portion of the zone damper
in a first position to substantially inhibit a flow of conditioned
air through a shell of the zone damper, the position of the
mechanical blade portion in the first position responsive to a
signal; enabling movement of the mechanical blade portion in a
predetermined range while in the first position, the movement of
the mechanical blade portion responsive to a static pressure
differential, so that the static pressure differential increasing
above a selected level causes movement of the mechanical blade
portion to bleed an amount of conditioned air past the mechanical
blade portion; and activating the actuator to drive the mechanical
blade portion to a second position, responsive to the signal, to
allow a maximum flow of conditioned air through the shell of the
zone damper, wherein the mechanical blade portion is not responsive
to the static pressure differential while in the second
position.
2. The method of claim 1, further comprising: activating the
actuator to drive the mechanical blade portion to a third position
to partially block the flow of conditioned air through the shell of
the zone damper responsive to the thermostat signal; and enabling
movement of the mechanical blade portion in a second predetermined
range while in the third position, responsive to the static
pressure differential increasing above a second selected level to
allow a variable amount of conditioned air past the mechanical
blade portion, the variable amount of conditioned air while the
mechanical blade portion is in the third position being greater in
volume than the amount of conditioned air while the mechanical
blade portion is in the first position.
3. The method of claim 2, wherein the predetermined range of the
mechanical blade portion in the first position is greater than the
second predetermined range of the mechanical blade portion in the
third position.
4. The method of claim 2, wherein the third position is between the
first position and the second position.
5. The method of claim 1, further comprising biasing the movement
of the mechanical blade portion to a first end of the predetermined
range by a biasing member.
6. The method of claim 1, wherein the movement of the mechanical
blade portion is caused by the static pressure differential.
7. The method of claim 1, wherein the mechanical blade portion is
coupled to the actuator by a shaft which passes through the shell
of the zone damper.
8. The method of claim 7, wherein movement of the mechanical blade
portion is limited to the predetermined range by the movement of a
projection within a slot, wherein one of the projection or the slot
is associated with the mechanical blade portion and the other of
the projection or the slot is associated the shaft.
9. The method of claim 1, further comprising providing the amount
of conditioned air to a zone.
10. A method of operating a zone damper comprising: activating an
actuator to drive a shaft to a first position responsive to a
temperature signal, wherein the shaft is coupled to a mechanical
blade portion of the zone damper; enabling movement of the
mechanical blade portion toward a first end of a predetermined
range about the shaft so that the mechanical blade portion is
substantially blocking a flow of conditioned air through a shell of
the zone damper, while the shaft is in the first position, enabling
variation in positioning of the mechanical blade portion within the
predetermined range by a static pressure differential so that the
static pressure differential increasing above a selected level
moves the mechanical blade portion to allow an amount of
conditioned air to bleed past the mechanical blade portion towards
a zone; and activating the actuator to drive the shaft to a second
position responsive to the temperature signal, to allow a
substantially unrestricted flow of conditioned air through the
shell of the zone damper towards a zone, wherein the mechanical
blade portion is not responsive to the static pressure differential
while the shaft is in the second position.
11. The method of claim 10, further comprising: activating the
actuator to drive the shaft to a third position, responsive to a
temperature signal; while the shaft is in the third position,
enabling movement of the mechanical blade portion toward the first
end of the predetermined range about the shaft, so that the
mechanical blade portion partially blocks the flow of conditioned
air through the shell of the zone damper; and enabling variable
movement of the mechanical blade portion in the predetermined range
while in the third position, by a static pressure differential
increasing above a second selected level or decreasing below the
second selected level to allow a variable amount of conditioned air
past the mechanical blade portion towards a zone, the variable
amount of conditioned air while the shaft is in the third position
being great in volume than the amount of conditioned air while the
shaft is in the first position.
12. The method of claim 11, wherein the predetermined range of the
movement of the mechanical blade portion while the shaft is in the
first position is greater than the predetermined range of movement
of the mechanical blade portion when the shaft is in the third
position.
13. The method of claim 11, wherein the third position is between
the first position and the second position.
14. The method of claim 10, further comprising biasing the movement
of the mechanical blade portion to a first end of the predetermined
range by a biasing member.
15. A method of operating a zone damper comprising: activating an
actuator, responsive to a thermostat signal, to drive a shaft of
the zone damper to a first position, the first position having a
first end element, wherein the shaft is coupled to a mechanical
blade portion of the zone damper, and wherein the first end element
defines a limit as to a range of motion of the mechanical blade
portion with respect to the first end element; while the shaft is
in the first position, enabling movement of the mechanical blade
portion to substantially block a flow of conditioned air through a
shell of the zone damper; while the shaft is in the first position,
enabling variable movement of the mechanical blade portion in the
range of motion, the variable movement of the mechanical blade
portion responsive to a static pressure differential, so that the
static pressure differential increasing above a selected level
causes movement of the mechanical blade portion to bleed an amount
of conditioned air past the mechanical blade portion; and
activating the actuator, responsive to the thermostat signal, to
drive the shaft to a second position to allow the flow of
conditioned air through the shell of the zone damper, wherein the
while the shaft is in the second position, the mechanical blade
portion is not responsive to the static pressure differential.
16. The method of claim 15, wherein the range of motion is defined
between the location of the first end element, and a point wherein
the mechanical blade portion is not responsive to the static
pressure differential.
17. The method of claim 16, further comprising: activating the
actuator to drive the shaft to a third position, responsive to a
thermostat signal, wherein the mechanical blade portion rests
against the first end element and is positioned to partially block
the flow of conditioned air through the shell of the zone damper;
and while the shaft is in the third position, enabling variable
movement of the mechanical blade portion in the range of motion
while in the third position, responsive to the static pressure
differential increasing above a second selected level to allow a
variable amount of conditioned air past the mechanical blade
portion, the variable amount of conditioned air while the shaft is
in the third position being great in volume than the amount of
conditioned air while the shaft is in the first position.
18. The method of claim 16, wherein the first end element is
located at a first end of a slot, and wherein variable movement of
the mechanical blade portion is limited by the movement of a
projection within the slot.
19. The method of claim 18, further comprising enabling variable
movement of the mechanical blade portion against a second end of
the slot to define a maximum responsiveness of the mechanical blade
portion to move in the range of motion in response to the static
pressure differential.
20. The method of claim 15, further comprising biasing the movement
of the mechanical blade portion to a first end of the range of
motion by a biasing member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/562,859 filed Jul. 31, 2012, which in turn
is a continuation-in-part of U.S. Ser. No. 13/463,952 filed May 4,
2012, which claims the benefit of U.S. Provisional Patent
Application Ser. No. 61/569,845 filed Dec. 13, 2011, all of which
are incorporated by reference.
BACKGROUND
[0002] This invention relates to heating, ventilating and air
conditioning ("HVAC") systems that include at least two zones
controlled by sensors, generally thermostats, located within the at
least two zones that control corresponding dampers in ducts leading
from usually a single HVAC source to the at least two zones.
[0003] In a conventional HAVC zoning system, conditioned air can be
supplied to a plurality of zones, each zone being controlled by its
own thermostat. Zoning systems for such an HVAC system typically
includes zone dampers disposed in the ductwork for controlling the
air flow of the conditioned air to the zones in response to the
thermostat. These zoning systems control the flow of conditioned
air to the plurality of zones independently so as to allow for
independent control of the zone environments. As a result, at any
given time a number of zone dampers may be open or closed. As the
temperature in each zone is satisfied, its zone damper will close
causing the static pressure in the duct system to rise. This rise
in static duct pressure can result in an increase in noise and
drafts due, in part, to an increase in air flow velocity though the
ducts in zones still calling for conditioned air.
[0004] Conventionally, a bypass damper system is used to relieve
excess static duct pressure. For example, a bypass damper can be
connected between the supply and return air duct. If the bypass
damper system determines that the air flow to a supply air duct is
causing excess static duct pressure, then the bypass damper will be
modulated open to recycle the conditioned air from the supply air
duct to the return air duct. This implementation has the
disadvantage of being energy inefficient, and hence an expensive
way to solve the problem. Bypass dampers can also be expensive to
install and difficult to setup. Elimination of the aforementioned
bypass damper system could reduce the amount of HVAC system
equipment, which, in turn, would reduce installation and
maintenance costs.
[0005] What is needed is alternative apparatus that can effectively
and efficiently control excess static duct pressure without
resorting to the use of a bypass damper.
SUMMARY
[0006] The alternative apparatus can take the form of each zone
damper being replaced with a zone damper that, in addition to being
controlled by the corresponding zone thermostat, also includes a
mechanical portion responsive to the barometric pressure
differential in the system to open and bleed a small amount of
conditioned air into each zone when the static pressure of the
system increases above a selected level.
[0007] In a preferred embodiment, the zone damper can include two
portions that are hinged to each other to permit independent
movement of the two portions relative to each other. A first of the
portions can be connected to a damper actuator controlled by a
corresponding zone thermostat to open and close in response to the
need for conditioned air within the zone. A second of the portions
can also be moved by the damper actuator from the closed position
to an open position to ensure maximum air flow through the duct in
response to the need for conditioned air within the zone. As the
first portion moves from the open position to the closed position,
the second portion can also move toward the closed position, but
may not entirely close if the static pressure differential in the
system is too high.
[0008] In a preferred embodiment, the second portion of the zone
damper can include a counter balance weight, which may be
adjustable, to set the desired static pressure differential value
that will be allowed. If the system static pressure differential
rises above the set desired pressure differential value, the second
portion responds by opening sufficiently to reduce the system
static pressure differential to the desired value. The counter
balance weight and adjustment mechanisms can be of a variety of
constructions. A removable access panel can be provided in the zone
ducting adjacent to the zone damper to permit access to and
adjustment of the counter balance weight to the desired level.
Additionally, a lock or stop can be provided to fix the position of
the second portion relative to the first portion or to set the
maximum deflection of the second portion relative to the first
portion in certain situations.
[0009] In a further preferred embodiment, the zone damper can
include a coupling mechanism between the damper blade and the
damper actuator that includes a provision for limited relative
movement so that the damper blade can respond to the barometric
pressure differential in the system to open and bleed an
appropriate amount of conditioned air into each zone when the
static pressure of the system increases above a selected level. The
coupling mechanism can include a shaft coupled to one of the damper
blade and damper actuator and a cylinder surrounding the shaft
coupled to another of the damper blade and damper actuator, one of
the shaft and cylinder including slot and the other of the shaft
and cylinder including a projection into the slot defining limits
to the relative movement between the shaft and cylinder. The shaft
and cylinder need not be of the same length.
[0010] A feature of the disclosed zone dampers is the inclusion of
barometrically responsive portions that effectively eliminate the
need for any bypass damper system and hence reduce the size of
damper inventory. An advantage of the disclosed zone dampers is a
reduction in drafts and air noise, and a reduction in coil freeze
up, with a resulting increase in system energy efficiency.
[0011] Other features and advantages of the present barometric zone
damper and the corresponding advantages of those features will
become apparent from the following discussion of preferred
embodiments, which is illustrated in the accompanying drawings. The
components in the figures are not necessarily to scale, emphasis
instead being placed upon illustrating the principles of operation.
Moreover, in the figures to the extent possible, like referenced
numerals designate corresponding parts throughout the different
views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a barometrically responsive
zone damper positioned within a shell.
[0013] FIG. 2 is a schematic side elevation view of a
barometrically responsive zone damper positioned within a
shell.
[0014] FIG. 3 is a schematic front elevation view of a
barometrically responsive zone damper positioned within a
shell.
[0015] FIG. 4 is a schematic front elevation view of another
barometrically responsive zone damper positioned within a
shell.
[0016] FIG. 5 is a schematic front elevation view of yet another
barometrically responsive zone damper positioned within a
shell.
[0017] FIG. 6 is a schematic front elevation view of still another
barometrically responsive zone damper positioned within a
shell.
[0018] FIG. 7 is a side elevation view of a lock down clip that can
be used on a barometrically responsive zone damper to control the
relative displacement of the first and second portions of the
damper with respect to each other.
[0019] FIG. 8 is a schematic sectional view of a barometrically
responsive zone damper moved to a partially open position by a
damper actuator.
[0020] FIG. 9 is a schematic sectional view of a barometrically
responsive zone damper in a closed position with a lower portion
being moved to a partially open position by virtue of a pressure
differential across the damper resulting in an air flow through the
duct.
[0021] FIG. 10 is a schematic sectional view of a barometrically
responsive zone damper that includes a coupling mechanism between
the damper blade and the damper actuator providing limited relative
movement between the damper blade and damper actuator.
[0022] FIG. 11 is a schematic sectional view of the barometrically
responsive zone damper of FIG. 10 moved to a partially open
position by a static pressure differential across the damper
resulting in an air flow.
[0023] FIG. 12 is a schematic sectional view of the barometrically
responsive zone damper of FIG. 10 moved to a fully open position by
the damper actuator.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] FIG. 1 shows a barometrically responsive zone damper 10
positioned within a segment of ducting 11, which forms a damper
shell 12. The damper 10 can include an upper portion 14 and a lower
portion 16. The upper portion 14 can be fixed to a shaft 18 mounted
in bushings fixed in the shell 12, the shaft 18 extending through
the shell 12. The position of the shaft 18 and upper portion 14 of
the zone damper 10 can be controlled by a damper actuator 22 that
can be located on the outside or inside of the shell 12. The damper
actuator 22 can be situated on either side of the shell 12 and
controlled by a zone thermostat, not shown. The lower portion 16 of
the zone damper 10 is connected to the upper portion 14 of the
damper by a hinge 24 to permit independent movement of the lower
portion 16 relative to the upper portion 14. In the absence of a
sufficient air pressure differential or air flow through the
ducting 11, the force of gravity will cause the lower portion 16 to
pivot to a position in alignment with the upper portion 14 as
shown. The force acting to close the lower portion 16 can be
increased by attaching a weight 26 of selected size to the lower
portion 16.
[0025] The amount of the force acting to close the lower portion 16
can be modified by modifying the size of the weight 26 or by
adjusting the position the weight 26 so as to increase or decrease
the torque applied to the lower portion 16 as shown in FIG. 1 and
FIG. 3. A removable access panel 25 can be provided in the shell 12
adjacent to the zone damper 10 to permit access to and adjustment
of the counter balance weight 26 to the desired level. FIG. 3 also
shows the upper portion 14 fixed to the shaft 18, which can be
mounted in bushings 20, which can be formed of nylon or similar
durable material, fixed in the shell 12, the shaft 18 extending
through the shell 12. Both portions 14 and 16 are shown to have a
gasket 15, 17 adjacent to the shell 12 to provide a suitable seal
to prevent unwanted leaking past the zone damper 10. A lock 34 can
also be provided to fix the position of the lower portion 16 in
relation to the upper portion 14. The lock 34 can take the form of
a butterfly blade lock 36. When barometric pressure differential
relief is desired, the butterfly blade lock 36 can be rotated from
the locked position shown in FIG. 1 to a horizontal un-locked
position as shown in FIG. 4.
[0026] A variations of the barometric zone damper is shown in FIG.
2, which is a schematic side elevation view of a barometrically
responsive zone damper 10 positioned within a shell 12. The damper
10 is shown to include an upper portion 14 and a lower portion 16.
The position of the upper portion 14 of the zone damper 10 can be
controlled by a damper actuator 22 that can be located on the
outside of the shell 12. The damper actuator 22 can be controlled
by a zone thermostat, not shown. The lower portion 16 of the zone
damper 10 is connected to the upper portion 14 in a manner to
permit independent movement of the lower portion 16 relative to the
upper portion 14. In the absence of a sufficient air pressure
differential on opposite sides of the zone damper 10, or any air
flow through the ducting 11, the force of gravity will cause the
lower portion 16 to pivot into alignment with the upper portion 14.
Gaskets 27 can be included in the shell 12 to seal against damper
portions 14 and 16 when the portions are in a closed position. One
or more weights 26 can be added to or subtracted from a screw 28
located adjacent to a lower margin 30 of the lower portion 16 to
increase or decrease the force acting to close the lower portion
16.
[0027] FIG. 4 shows a schematic front elevation view of another
barometrically responsive zone damper 10 positioned within a shell
12. The damper 10 is shown to include an upper portion 14 and a
lower portion 16. The position of the upper portion 14 of the zone
damper 10 can be controlled by a damper actuator 22 located on the
outside of the shell 12. The lower portion 16 is connected to the
upper portion 14 in a manner to permit independent movement of the
lower portion 16 relative to the upper portion 14. In the absence
of a sufficient air pressure differential on opposite sides of the
zone damper 10, or any air flow through the shell 12, the force of
gravity will cause the lower portion 16 to pivot into alignment
with the upper portion 14. A lock 34 can also be provided to fix
the position of the lower portion 16 in relation to the upper
portion 14. The lock 34 can take the form of a butterfly blade lock
36. If, in a particular installation, no barometric pressure
differential relief is deemed necessary, the butterfly blade lock
36 can be rotated from the un-locked position shown in FIG. 4 to a
vertical locked position, in which case the damper 10 would perform
as a conventional zone control damper.
[0028] FIG. 5 is a schematic front elevation view of yet another
barometrically responsive zone damper 10 positioned within a shell
12. The damper 10 is shown to include an upper portion 14 and a
lower portion 16. The position of the upper portion 14 of the zone
damper 10 can be controlled by a damper actuator 22 located on the
outside of the shell 12. It is to be noted that in this embodiment,
no counter balance weight is coupled to portion 16. Instead, the
portion 16 is connected to the portion 14 by spring biased hinges
23, each incorporating a helical torsion spring 54, the hinges
permitting independent movement of the portion 16 relative to the
portion 14 and the springs 54 providing a desired biasing force. In
the absence of a sufficient air pressure differential on opposite
sides of the zone damper 10, or any air flow through the shell 12,
the force provided by the spring biased hinges 23 will cause the
lower portion 16 to pivot into alignment with the upper portion 14.
The amount of force can be determined by specifying the strength of
the spring element 54 included in the spring biased hinges 23, or
by specifying the number of spring biased hinges coupling the upper
portion 14 to the lower portion 16. While the spring element 54
providing the biasing force has been illustrated as being
incorporated into a spring biased hinge 23, the spring can take
other forms including, for example, a leaf or bow spring, or a
volute spring, coupled to both the upper portion 14 and the lower
portion 16. The shaft 18 can be located at any angle relative to
HVAC system as a whole, since the position of portion 16 in
relation to portion 14 is not governed entirely by gravity, but
rather by the force supplied by the one or more springs. This
allows for the barometrically responsive zone damper 10 to be
located in a duct 12 that may be vertically oriented or at least
inclined so that the force opposing any pressure differential is
only partly dependent on gravity.
[0029] A lock 34 can also be provided to fix the position of the
lower portion 16 in relation to the upper portion 14. The lock 34
in FIG. 5 takes the form of a strap 38, which can include a series
of holes 40 or a slot permitting the strap to be adjusted from an
unlocked position as shown in FIG. 5 to a position where a lower
end 42 of the strap 38 overlaps at least a portion of lower portion
16 to maintain the upper portion 14 and lower portion 16 in
alignment with each other. When the strap 38 is in the locked
position, the damper 10 would perform as a conventional zone
control damper.
[0030] FIG. 6 is a schematic front elevation view of still another
barometrically responsive zone damper 10 positioned within a shell
12, which is shown to be rectangular. The shape of the perimeter of
the zone damper 10 can be formed in any shape necessary for a given
installation. Again, damper 10 is shown to include an upper portion
14 and a lower portion 16. The position of the upper portion 14 of
the zone damper 10 can be controlled by a damper actuator. FIG. 6
shows a damper actuator 22 that has a sufficiently low profile to
lie in the region of a damper frame 47 surrounding the shell 12,
and between the shell 12 and a damper mounting plate 49 supporting
the damper 10 in the related HVAC system. As in the other
embodiments, the lower portion 16 is connected to the upper portion
14 by hinges 24 to permit independent movement of the lower portion
16 relative to the upper portion 14. In the absence of a sufficient
air pressure differential on opposite sides of the zone damper 10,
or any air flow through the shell 12, the force of gravity will
cause the lower portion 16 to pivot into alignment with the upper
portion 14. A lock 34 can also be provided to fix the position of
the lower portion 16 in relation to the upper portion 14. The lock
34 in FIG. 5 takes the form of a strap 38, which includes a slot 44
permitting the strap to be adjusted from an unlocked position as
shown in FIG. 6 to a position where a lower end 42 of the strap 38
overlaps at least a portion of lower portion 16 to maintain the
upper portion 14 and lower portion 16 in alignment with each other.
When the strap 38 is in the locked position, the damper 10 would
perform as a conventional zone control damper.
[0031] The strap 38 can also take the form shown in FIG. 7 is a
side elevation view of a clip 46 that includes a first portion 48
that can be coupled to a surface of the upper damper portion 14.
The clip 46 can also include a second portion 50 that can be
inclined at an angle a with respect to portion 48. The clip first
portion 48 can be positioned on the upper damper portion 14 so that
the junction 52 of the portions 48 and 50 overlies the junction of
the upper damper portion 14 and the lower damper portion 16. The
angle a of the clip 46 sets a maximum deflection that the second
portion 16 of the damper 10 can achieve relative to the first
portion 14. While FIG. 7 shows the portions 48 and 50 of clip 46 to
be inclined at an angle of about 110.degree. relative to each
other, the angle can range between about 90.degree. and
140.degree.. While FIG. 7 shows the length L.sub.1 of portion 48 to
be greater than the length L.sub.2 of portion 50, the portions 48
and 50 may be of equal length.
[0032] An appreciation of the operation of the barometrically
responsive zone dampers 10 can be gained from a consideration of
FIGS. 8 and 9 in which the damper 10 includes a first portion 14
and a second portion 16. The first portion 14 is fixed to shaft 18
so that any rotation of shaft 18 will cause a corresponding angular
displacement of the portion 14. The position of the shaft 18 and
first portion 14 of the zone damper 10 can be controlled by a
damper actuator 22 that can be, in turn, controlled by a zone
thermostat, not shown. The second portion 16 is connected by one or
more hinges to the first portion 14 to permit independent movement
of the second portion 16 relative to the first portion 14. A
biasing force supplied by one or more weights, springs, or other
biasing means, or a locking element can be suitably positioned, to
maintain the second portion 16 in alignment with the first portion
14 as shown in FIG. 8. As the shaft 18 rotates from a closed
position C, in which the damper 10 blocks air flow through the duct
12, to a partially open position O, in which air can flow through
the duct 12 past the damper 10, both portions 14 and 16 move with
the rotation of the shaft 18 in the manner of a conventional zone
control damper.
[0033] In the absence of a locking element, or with the locking
element situated in an un-locked position allowing relative
movement between second portion 16 and first portion 14, the
rotation of shaft 18 will still cause a corresponding angular
displacement of the portion 14. Portion 16, however, is free to
respond to a pressure differential across the damper 10, which if
sufficient to overcome the biasing force, will allow portion 16 to
open to a relief position R even though portion 14 remains in the
closed position C as shown in FIG. 9 to bleed a sufficient amount
of air through the duct 12 to keep the static pressure differential
from rising to an unacceptable level.
[0034] With each of the illustrated variations, if the system
static pressure differential rises above the set desired pressure
value, the lower or second portion 16 of the zone damper 10 can
respond by opening sufficiently to reduce the system static
pressure to a desired value. In a preferred system, the biasing
force supplied by the one or more springs, or by the weights 26,
can be such that the second or lower portion 16 of the damper 10
will begin to open independent of the first portion 14 at
approximately 0.3'' WC of static pressure. The use of any of the
illustrated variations of barometric zone dampers effectively
eliminates the need for any bypass damper system.
[0035] FIGS. 10-12 show the operation of a zone damper 10 of a
slightly different design that includes a shell 12 containing a
damper blade 14 coupled to a shaft 18. The damper blade 14 can be
in the form of a one piece, un-divided blade. A cylinder 56 can
surround at least a portion of the shaft 18, the cylinder 56 being
controlled by an actuator 22. The shaft 18 is shown to include a
slot 58, while the cylinder 56 is shown to include a projection 60
that projects into the slot 58. The cylinder 56 is movable by the
actuator 22 between a closed position shown in FIG. 10, and an open
position shown in FIG. 12 in response to a suitable thermostat, not
shown. The damper blade 14 and shaft 18 are movable relative to the
cylinder 56 in response to the static pressure differential in an
HVAC system as shown, for example in FIG. 11, to bleed an amount of
conditioned air past the damper blade 14 when the static pressure
differential of the system increases above a selected level. The
end 62 and end 64 of slot 58, shown in FIG. 11, define the limits
of travel of the projection 60 within the slot 58 and the
corresponding limits of travel of the shaft 18 within the cylinder
56. As in the prior embodiments, the force acting to close the
damper blade 14 can be increased by attaching a weight 26 of
selected size to a suitable location on the damper blade. The
amount of the force acting to close the damper blade 14 can be
modified by modifying the size of the weight 26 or by adjusting the
position the weight 26 so as to increase or decrease the torque
applied to the damper blade.
[0036] It will be appreciated by those skilled in the art that the
shaft 18 could be coupled to the actuator 22, while the cylinder 56
could be coupled to the damper blade 14. It will also be
appreciated by those skilled in the art that the slot 58 could be
located on the interior surface of the cylinder 56, while the
projection 60 could project outward from the shaft 18 into the
slot. The shaft 18 and cylinder 56 need not be of the same length.
While the slot 58 is shown to provide for about 90.degree. of
relative movement between the shaft and cylinder, the scope of
relative movement is subject to some choice of design and may be
limited or enlarged to provide less or more relative movement. It
will also be appreciated by those skilled in the art that a
suitable spring could be substituted for the weight 26 to provide
the desired biasing force, the spring being coupled, for example,
between the shaft 18 and the cylinder 56.
[0037] While these features have been disclosed in connection with
the illustrated preferred embodiments, other embodiments of the
invention will be apparent to those skilled in the art that come
within the spirit of the invention as defined in the following
claims.
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