U.S. patent application number 11/715713 was filed with the patent office on 2007-09-20 for variable air volume control apparatus.
Invention is credited to Wan-Ki Baik.
Application Number | 20070218827 11/715713 |
Document ID | / |
Family ID | 37867292 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070218827 |
Kind Code |
A1 |
Baik; Wan-Ki |
September 20, 2007 |
Variable air volume control apparatus
Abstract
The present invention relates to a variable air volume control
apparatus capable of effectively reducing air overflow concentrated
at one side due to a damper blade biased according to an open angle
of the damper blade, thereby precisely adjusting the air volume.
The variable air volume control apparatus includes a damper blade
disposed rotatably inside the duct to open or close an air flow
path and an actuator for rotating the damper blade. The apparatus
also includes means for dividing the air flow path inside the duct
at the air inlet side into an upper region and a lower region and
exerting resistance to the air flow between the means and the
biased damper blade. The invention effectively suppresses the air
overflow occurring at high opening ratio of the damper blade with
simple structural improvements, thereby accurately and precisely
adjusting the air volume.
Inventors: |
Baik; Wan-Ki; (Seoul,
KR) |
Correspondence
Address: |
Paul M. Denk
Ste. 170
763 S. New Ballas Road
St. Louis
MO
63141
US
|
Family ID: |
37867292 |
Appl. No.: |
11/715713 |
Filed: |
March 1, 2007 |
Current U.S.
Class: |
454/246 |
Current CPC
Class: |
F24F 13/1406 20130101;
F24F 2110/30 20180101; F24F 11/30 20180101; F24F 2110/10 20180101;
F24F 11/76 20180101 |
Class at
Publication: |
454/246 |
International
Class: |
F24F 13/08 20060101
F24F013/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2006 |
KR |
2006-21949 |
Claims
1. A variable air volume control apparatus for adjusting air flow
volume in a duct comprising: a damper blade disposed rotatably in
the duct to open or close an air flow path; an actuator for
rotating the damper blade; and means for dividing the air flow path
in the duct at an air inlet side into an upper region and a lower
region with respect to a rotation axis of the damper blade, wherein
resistance is exerted to an air flow between a portion of the
damper blade biased toward the air inlet side and the flow path
dividing means.
2. The variable air volume control apparatus according to claim 1,
wherein the flow path dividing means comprises a separation plate
disposed in a front side of the damper blade to dichotomize the
duct.
3. The variable air volume control apparatus according to claim 1,
wherein the flow path dividing means has a diameter 0.5 times
larger than that of the duct.
4. The variable air volume control apparatus according to claim 2,
wherein the separation plate has sealing material at an end
thereof, the sealing material providing sealing between the end of
the separation plate and a portion of the rotation axis of the
damper blade.
5. The variable air volume control apparatus according to claim 1,
wherein the rotation axis of the damper blade and the air flow path
dividing means are shifted upward or downward from the center of
the duct.
6. The variable air volume control apparatus according to claim 5,
further comprising a flow path blocking means for blocking an open
region between an outer surface of the damper blade and the
duct.
7. The variable air volume control apparatus according to claim 6,
wherein the flow path blocking means comprises a blocking plate in
a crescent shape fixed to the duct.
8. The variable air volume control apparatus according to claim 1,
wherein the duct has a rectangular cross-section.
9. A variable air volume control apparatus comprising: a damper
blade disposed rotatably inside the duct to open or close an air
flow path; an actuator for rotating the damper blade; means for
expanding the air flow path according to an angle of the damper
blade that opens or closes the duct; and an air flow path dividing
means for dividing the air flow path inside the duct in an air
inlet side of the damper blade into an upper region and a lower
region with respect to a rotation axis of the damper blade, wherein
resistance is exerted to air flow between a apportion of the damper
blade biased toward the air inlet side and the flow path dividing
means.
10. The variable air volume control apparatus according to claim 9,
wherein the flow path expanding means comprises a curved surface
which compensates and expands the air flow path such that the air
flow path is opened in proportion to an open angle of the damper
blade at a small value of open angle rather than by a function of
"1-COS .theta." of the open angle.
11. The variable air volume control apparatus according to claim
10, wherein the air flow path expanding means comprises a ring
structure that is installable on an inner surface of the duct, and
the damper blade has a circumference the same as an inner
circumference of the ring structure.
12. The variable air volume control apparatus according to claim
10, wherein the flow path expanding means is formed to compensate
an opening ratio of (.theta./90)-(1-COS .theta.) at a small value
of open angle, where .theta. is an arbitrary angle in which the
damper blade is opened.
13. The variable air volume control apparatus according to claim
10, wherein the rotation axis of the damper blade and the flow path
dividing means are shifted upward or downward from the center of
the duct, and the air flow path expanding means is disposed between
an outer edge of the damper blade and the duct.
14. The variable air volume control apparatus according to claim 9,
wherein the air flow path expanding means comprises a ring
structure that is installable on an inner surface of the duct, and
the damper blade has a circumference the same as an inner
circumference of the ring structure.
15. The variable air volume control apparatus according to claim 9,
wherein the flow path expanding means is formed to compensate an
opening ratio of (.theta./90)-(1-COS .theta.) at a small value of
open angle, where .theta. is an arbitrary angle in which the damper
blade is opened.
16. The variable air volume control apparatus according to claim 9,
wherein the rotation axis of the damper blade and the flow path
dividing means are shifted upward or downward from the center of
the duct, and the air flow path expanding means is disposed between
an outer edge of the damper blade and the duct.
Description
CLAIM OF PRIORITY
[0001] This application claims the benefit of Korean Patent
Application No. 2006-21949 filed on Mar. 8, 2006, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a variable air volume
control apparatus for automatically adjusting the volume of air
supplied indoors, according to the temperature change therein. More
particularly, the invention relates to a variable air volume
control apparatus having an air flow path dividing means for
dividing an air flow path of a duct into an upper and lower regions
to exert resistance to air flow between a damper blade and the air
flow path dividing means, effectively suppressing air overflow with
the damper blade biased at high opening ratio, thereby precisely
and accurately adjusting the volume of air.
[0004] 2. Description of the Related Art
[0005] In general, an automatic control system of a building is
equipped with a variable air volume control apparatus for varying
the volume of air from the outside in order to maintain the room
temperature by conditioning air inside the building.
[0006] FIG. 1 illustrates a conventional variable air volume
control apparatus.
[0007] The conventional variable air volume control apparatus 200
is installed inside a duct 210 through which air from the outside
is introduced. The variable air volume control apparatus 200
includes a flow sensor 220 for sensing the volume of air introduced
from the outside, a damper blade 230 for adjusting the volume of
air introduced from the outside to the inside, and an actuator 240
for rotating the damper blade 230.
[0008] Also, the conventional variable air volume control apparatus
200 includes a room thermostat 250 for detecting and setting the
temperature indoors and a controller 260 for controlling the
operation of the variable air volume control apparatus 200.
[0009] The flow sensor 220, the actuator 240 and the room
thermostat 250 are electrically connected to the controller 260 to
thereby be controlled.
[0010] The above variable air volume control apparatus 200 controls
the volume of air through a following process.
[0011] The room thermostat 250 installed indoors senses the room
temperature, and the information thereof, e.g. a signal is sent to
the controller 260. Then, the controller 260 computes the
information and the currently set temperature to calculate the air
volume needed, thereby transmitting a signal for the opening angle
corresponding to the air volume needed to the operational devices
such as a motor or the actuator 240 to be operated accordingly.
[0012] In addition, the above variable air volume control apparatus
200 measures the volume of air at an inlet side by an air volume
measurement device such as an anemometer or a differential pressure
sensor installed at the air inlet side and sends the corresponding
information (signal) to the controller 260. Then, the controller
260 receives and processes the information (signal) from the air
volume measurement device to rotate a shaft 232 of the operational
device as much as the excessive or deficient amount of air volume
to adjust the angle of the damper blade 230, thereby maintaining
the air volume in accordance with the information from the room
thermostat 250.
[0013] However, the conventional variable air volume control
apparatus 200 shown in FIG. 1 entails great imbalance between the
opening ratio and the open area ratio corresponding to the open
angle of the damper blade 230, air overflow, and friction between
air flow and an inner surface of the duct 210. Thus, the open area
ratio and the volume of air flowing through the duct in accordance
with the opening ratio of the damper blade 230 is not in direct
proportion to each other. Therefore, the air volume change ratio
and the open area ratio are represented in distorted curves rather
than in lines, as shown in FIG. 2.
[0014] FIG. 2 is a graph showing characteristics of the
conventional variable air volume control apparatus such as the open
area ratio and the air volume change ratio with respect to the
opening ratio of the damper blade 230.
[0015] Characteristically most ideal for the above variable air
volume control apparatus 200 is to have the open area ratio and the
air volume change ratio in direct proportion to the opening ratio.
Such directly proportional relationship is most desirable because
it enables the controller 260 of the variable air volume control
apparatus 200 to adjust the open angle as desired through the
actuator 240 and the damper blade 230, thereby precisely and
accurately adjusting the volume of air.
[0016] As shown in FIG. 2, with the conventional variable air
volume control apparatus 200, the open area ratio as represented by
curve (a) in FIG. 2 deviates greatly from line (c) directly
proportional to the opening ratio of the damper blade 230.
[0017] The reason for this is because, as shown in FIG. 1,
supposing that the diameter of the damper blade 230 or the diameter
D of the duct 210 is 1 and the damper blade 230 is rotated in an
arbitrary angle .theta., the opened area created by the end portion
of the damper blade 230 separated from an inner surface of the duct
210, i.e., the area through which the air can flow corresponds to a
cosine function of 1-cos .theta..
[0018] The area corresponding to the cosine function of 1-cos
.theta. applies to the entire range from the vertical position of
the damper blade 230 to completely block the air flow path, i.e.,
when .theta. is 0.degree. to the horizontal position of the damper
blade 230 to completely open the air flow path, i.e., when .theta.
is 90.degree..
[0019] As shown by curve (b) in FIG. 2, at a low opening ratio (0%
to 33%) of the damper blade 30 rotated in an arbitrary angle
.theta., i.e., at the open angle .theta. of 0.degree. to
30.degree., the actual air volume change ratio is lower than the
ideal air volume change ratio which is in direct proportion to line
(c) but substantially in proportion to the open area ratio.
[0020] On the other hand, at a high opening ratio (50% to 100%),
i.e., at the open angle .theta. of 45.degree. to 90.degree., air
flow crowds into only certain portion due to the biased damper
blade 230 to result in air overflow so that air flow is greater
than the corresponding open area ratio is supposed to permit.
[0021] As shown by the air volume change ratio curve (b) in
comparison to the open area ratio curve (a), the air volume change
ratio is more excessive at greater opening ratio.
[0022] The reason for this is because, at small opening ratio (0%
to 33%), i.e., at the open angle .theta. of 0.degree. to
30.degree., the open area ratio of the damper blade 230 is smaller
than the directly proportional opening ratio line (c) with the
damper blade 230 opened too narrowly by a cosine function of 1-cos
.theta. with the air flow path constricted. At such a small open
angle .theta., the biased damper blade 230 hinders the air flow and
thus the air volume change ratio is relatively small.
[0023] However, at a high opening ratio (50% to 100%), i.e., the
open angle .theta. of 45.degree. to 90.degree., although the open
area ratio of the damper blade 230 is relatively smaller than line
(c) which is in direct proportion to the opening ratio, the biased
damper blade 230 does not hinder the air flow. That is, as shown in
FIG. 3, the air flow in the upper area of the rotation axis 230a of
the damper blade 230 is induced toward the lower area thereof at
this range of opening ratio, thereby resulting in air overflow.
[0024] As a result, with respect to the opening ratio, the air
volume change ratio is expressed as curve (b) in FIG. 2, which
forms an "S" line deviating greatly from line (c) which is in
direct proportion to the opening ratio.
[0025] Particularly, the air overflow occurring at an opening ratio
of more than 50% hinders accurate control of air flow introduced
indoors, which is a major reason for failing to accurately and
precisely adjust the room temperature.
[0026] That is, when the opening ratio is 50% or less, the air
volume change ratio is similar to the open area ratio, but is too
smaller than line (c) which is in direct proportion to the opening
ratio, showing that it is difficult to adjust the volume of air via
manipulating the opening ratio. When the opening ratio is 50% or
greater, the open area ratio is smaller than the line in direct
proportion to the opening ratio whereas the air volume change ratio
is much greater than the line in direct proportion to the opening
ratio. Thus, the open area ratio curve (a) and the air volume
change ratio curve (b) have completely different forms from each
other. As a result, the user cannot adjust the air volume via
adjusting the opening ratio.
[0027] Therefore, the air overflow with the conventional variable
air volume control apparatus 200 must be suppressed to accurately
and precisely adjust the air volume in accordance with the opening
ratio.
[0028] In order to overcome such a problem, Korean Utility Model
Registration No. 0376799 (entitled "Variable Air Volume Control
Device") has been proposed.
[0029] In this conventional variable air volume control apparatus,
a shaft is disposed movable back and forth and connected to a guide
lever of a damper actuator disposed outside the apparatus body and
operated by a room thermostat. Also, a pair of symmetrical air
volume control dampers are split or joined in accordance with the
movement of a pair of links that are connected to an end of the
shaft. And an air conduit connects between an air inlet and a first
air outlet, and is connected to a mixed air outlet.
[0030] However, this structure is structurally complex, thus
difficult to manufacture, and expensive. Further, it uses a guide
lever in a link structure, which makes noise and the resultant air
volume change ratio curve has non-linear characteristics.
[0031] A different structure from the above is disclosed in U.S.
Pat. No. 5,333,835 (entitled "Electric Motor Driven Air
Valve").
[0032] In this structure, a screw shaft is rotated by a motor to
thereby move a damper blade connected to the screw shaft, adjusting
the volume of air flowing between the opened damper blade and the
duct.
[0033] However, it is also difficult with this conventional
structure to accurately adjust air volume according to the opening
ratio of the damper. Further, the structure is expensive and
frequently breaks down because of structural complexity.
SUMMARY OF THE INVENTION
[0034] The present invention has been made to solve the foregoing
problems of the prior art and therefore an object of certain
embodiments of the present invention is to provide a variable air
volume control apparatus which effectively suppresses air overflow
at a high opening ratio by simple structural improvements, thereby
accurately and precisely adjusting air volume.
[0035] Another object of certain embodiments of the invention is to
provide a variable air volume control apparatus which can yield air
volume change ratio approximate to a line in direct proportion to
opening ratio of a damper blade in a high opening ratio range,
thereby accurately and precisely adjusting air volume.
[0036] According to an aspect of the invention for realizing the
object, there is provided a variable air volume control apparatus
for adjusting air flow volume in a duct comprising: a damper blade
disposed rotatably in the duct to open or close an air flow path;
an actuator for rotating the damper blade; and means for dividing
the air flow path in the duct at an air inlet side into an upper
region and a lower region with respect to a rotation axis of the
damper blade, wherein resistance is exerted to an air flow between
a portion of the damper blade biased toward the air inlet side and
the flow path dividing means.
[0037] Preferably, the flow path dividing means comprises a
separation plate disposed in a front side of the damper blade to
dichotomize the duct.
[0038] Preferably, the separation plate has sealing material at an
end thereof, which provides sealing between the end of the
separation plate and a portion of the rotation axis of the damper
blade.
[0039] Preferably, the variable air volume control apparatus
according to claim 1, wherein the flow path dividing means has a
diameter 0.5 to 3 times larger than that of the duct.
[0040] Preferably, the rotation axis of the damper blade and the
air flow path dividing means are shifted upward or downward from
the center of the duct.
[0041] Preferably, the variable air volume control apparatus
further comprises a flow path blocking means for blocking an open
region between an outer surface of the damper blade and the
duct.
[0042] Preferably, the flow path blocking means comprises a
blocking plate in a crescent shape fixed to the duct.
[0043] Preferably, the duct has a rectangular cross-section.
[0044] According to another aspect of the invention for realizing
the object, there is provided a variable air volume control
apparatus comprising: a damper blade disposed rotatably inside the
duct to open or close an air flow path; an actuator for rotating
the damper blade; means for expanding the air flow path according
to an angle of the damper blade that opens or closes the duct; and
an air flow path dividing means for dividing the air flow path
inside the duct in an air inlet side of the damper blade into an
upper region and a lower region with respect to a rotation axis of
the damper blade, wherein resistance is exerted to air flow between
a apportion of the damper blade biased toward the air inlet side
and the flow path dividing means.
[0045] Preferably, the flow path expanding means comprises a curved
surface which compensates and expands the air flow path such that
the air flow path is opened in proportion to an open angle at a
small open angle rather than by a function of "1-COS .theta."
according to an open angle of the damper blade.
[0046] Preferably, the air flow path expanding means comprises a
ring structure that is installable on an inner surface of the duct,
and the damper blade has a circumference the same as an inner
circumference of the ring structure.
[0047] Preferably, the flow path expanding means is formed to
compensate an opening area of (.theta./90)-(1-COS .theta.) at a
small open angle, where .theta. is an arbitrary angle in which the
damper blade is opened.
[0048] Preferably, the rotation axis of the damper blade and the
flow path dividing means are shifted upward or downward from the
center of the duct, and the air flow path expanding means is
disposed between an outer edge of the damper blade and the
duct.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0050] FIG. 1 is a view illustrating a conventional air volume
control apparatus;
[0051] FIG. 2 is a graph illustrating the open area ratio and the
air volume change ratio with respect to the opening ratio, obtained
by the conventional variable air volume control apparatus;
[0052] FIG. 3 is a view illustrating air overflow in the
conventional variable air volume control apparatus;
[0053] FIG. 4 is a configuration view illustrating a variable air
volume control apparatus according to the present invention;
[0054] FIG. 5 is a sectional view illustrating the variable air
volume control apparatus according to the present invention;
[0055] FIG. 6 is a view illustrating prevention of air overflow by
the variable air volume control apparatus according to the present
invention;
[0056] FIG. 7 is a graph representing the open area ratio and the
air volume change ratio with respect to the opening ratio, obtained
by the variable air volume control apparatus according to the
present invention;
[0057] FIG. 8 is a view illustrating variations of the variable air
volume control apparatus according to the present invention, in
which the damper blade and the air flow path dividing means are
shifted downward from a center of a duct;
[0058] FIG. 9 is a view illustrating variations of the air volume
control apparatus according to the present invention, in which the
damper blade and the air flow path dividing means shifted variously
such as upward, downward, forward and backward;
[0059] FIG. 10 is a view illustrating another variation of the
variable air volume control apparatus according to the present
invention including both the air flow path dividing means and the
air flow path expanding means; and
[0060] FIG. 11 is a graph representing the open area ratio and the
air volume change ratio with respect to the opening ratio, obtained
by the variable air volume control apparatus according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0061] Preferred embodiments of the present invention will now be
described in detail with reference to the accompanying
drawings.
[0062] As shown in FIGS. 4 and 5, the variable air volume control
apparatus 1 according to the present invention includes a flow
sensor 20 installed in a duct 10 to sense the volume of air
introduced from the outside, a damper blade 30 for adjusting the
volume of air introduced from the outside to the inside, and an
actuator 40 for rotating the damper blade 30.
[0063] In addition, a room thermostat 50 is provided to detect and
set room temperature, and a controller 60 is provided to control
the operation of the variable air volume control apparatus 1.
[0064] The flow sensor 20, the actuator 40, and the room thermostat
50 are electrically connected to the controller 60 to thereby be
controlled.
[0065] In addition, the present invention includes an air flow path
dividing means 70 disposed in the front side of the damper blade 30
(hereinafter referred to as "the air inlet side") to divide the air
flow path inside the duct 10 into an upper region S1 and a lower
region S2 with respect to a rotation axis 30a of the damper blade
30.
[0066] Such an air flow path dividing means 70 exert resistance to
air flow between a portion of the damper blade 30 biased toward the
air inlet side and the air flow path dividing means 70.
[0067] The air flow path dividing means 70 is preferably a
separation plate 72 which is disposed in the front side of the
damper blade 30 to dichotomize the duct 10. A holder (not shown)
can be installed on an inner surface of the duct 10 to fix the
separation plate 72.
[0068] In addition, the separation plate 72 has sealing material at
a proximal end thereof, which provides sealing between the proximal
end of the separation plate 72 and a portion of the rotation axis
of the damper blade 30.
[0069] The air flow path dividing means has a diameter at least 0.5
times that of the duct, and preferably 0.5 to 3 times that of the
duct.
[0070] As shown in FIG. 6, the variable air volume control
apparatus 1 with the above configuration adjusts air volume from
the open angle .theta. of 0.degree. where the damper blade 20 is
vertically positioned to block the air flow path, to the open angle
.theta. of 90.degree. where the air flow path is completely
opened.
[0071] In the above process, according to the variable air volume
control apparatus 1 of the present invention, as the damper blade
30 is opened in an arbitrary angle .theta., air flow is divided
into the upper region S1 air flow and the lower region S2 air flow
by the air flow path dividing means 70 disposed in the front side
of the damper blade 30 to be delivered toward the damper blade
30.
[0072] With an upper portion of the damper blade 30 biased forward,
the upper region S1 with the upper air flow is divided into an open
flow path P1 of an upper part of the damper blade 20 and a closed
space P2 enclosed by the damper blade 30 and the air flow path
dividing means 70.
[0073] Air flows well in the open air flow path P1, but the air
flow is blocked and affected by great resistance in the closed
space P2. Therefore, the air flow is greatly restricted in the
upper region S1 of the damper blade 30 in the present
invention.
[0074] On the other hand, with the damper blade 30 biased backward,
the air in the lower region S2 of the air flow path dividing means
70 passes well through an air flow path P3 formed between the
damper blade 30 and the duct 10 and is supplied to the back of the
damper blade 30.
[0075] In the above variable volume control apparatus 1 according
to the present invention, the closed space P2 enclosed by the
damper blade 30 and the air flow path dividing means 70 blocks the
air flow from the upper region S1 to the lower region S2, exerting
great resistance to the air flow in the upper region S1 of the air
flow path dividing means 70, thereby effectively suppressing the
air overflow at a high opening ratio (50% or more) with the air
flowing over the biased damper blade 30.
[0076] Therefore, the air overflow occurring at a high opening
ratio of the damper blade 30 is suppressed to prevent excessive air
flow according to the present invention.
[0077] FIG. 7 is a graph illustrating the open area ratio and the
air volume change ratio with respect to the opening ratio, obtained
by the variable air volume control apparatus according to the
present invention described above.
[0078] In the variable air volume control apparatus, the closed
space P2 formed by the air flow path dividing means 70 blocks the
air flow from the upper region S1 to the lower region S2, causing
great resistance to the air flow in the upper region S1 of the air
flow path dividing means 70, thereby effectively suppressing the
air overflow at a high opening ratio (50% or more) of the damper
blade 30, as shown by curve (e) in FIG. 7.
[0079] Therefore, according to the present invention, the air
overflow occurring at the opening ratio of 50% or more is
effectively suppressed to prevent excessive air flow.
[0080] In addition, in the present invention, the rotation axis 30a
of the damper blade and the air flow path dividing means 70 are
preferably shifted upward or downward from the initial position of
the rotation axis 30a of the damper blade 30.
[0081] Such shifted structures are illustrated in FIG. 8. In the
variable air volume control apparatus 1' shown in FIG. 8, the
rotation axis 30a of the damper blade 30 and the air flow path
dividing means 70 are shifted downward in a predetermined distance
L from a center K of the rotation axis 30a of the damper blade
30.
[0082] Such shifted structures are useful in the variable volume
control apparatus having the upper part of the damper blade 30
opened forward and the lower part of the damper blade 30 opened
backward, as shown in FIG. 8.
[0083] As discussed herein, the air flows from the upper region to
the lower region over the damper blade 30 to result in the air
overflow at the opening ratio of 50% or more of the damper blade
30. Thus when the rotation axis 30a of the damper blade 30 and the
air flow path dividing means 70 are shifted downward from the
center K of the duct, the area of the closed space P2 enclosed by
the damper blade 30 and the air flow path dividing means 70 is
considerably increased from D/2 to D/2+L. Therefore, the resistance
to the air flow is increased in the upper region of the damper
blade 30, thereby more effectively suppressing the air overflow
caused by the air flowing from the upper region to the lower region
over the damper blade 30.
[0084] In order for the damper blade 30 to rotate in the duct 10 in
such a shifted structure, the diameter of the damper blade 30
should be maximal in the portion of its rotation axis 30a.
[0085] The variable air volume control apparatus 1' of the present
invention further includes an air flow path blocking means 80 for
blocking an open region formed between an outer surface of the
damper blade 30 and the duct 10. As shown in FIG. 8(b), the air
flow path blocking means 80 is a blocking plate in a crescent
shape, which is fixed above the damper blade 30 by screws 82,
etc.
[0086] With the rotation axis 30a of the damper blade 30 and the
air flow path dividing means 70 shifted downward from the center K
of the duct in a predetermined distance L, the air overflow is more
effectively suppressed in the structure in which the upper part of
the damper blade 30 opened forward, and the lower part of the
damper blade 30 opened backward.
[0087] FIG. 8 illustrates the structure in which the rotation axis
30a of the damper blade 30 and the air flow path dividing means 70
are shifted downward from the center K of the duct in a
predetermined distance L, which however does not limit the present
invention. Alternatively, the rotation axis 30a of the damper blade
30 and the air flow path dividing means 70 can be shifted upward
from the center K of the duct.
[0088] In this case, the air flow path blocking means 80 is fixed
to the duct below the damper blade 30, which more effectively
suppresses the air overflow in the structure in which the upper
part of the damper blade 30 opened backward and the lower part of
the damper blade 30 opened forward.
[0089] Therefore, the shift distance L of the rotation axis 30a of
the damper blade 30 and the air flow path dividing means 70 can be
adjusted to more effectively control the air overflow occurring at
high opening ratio.
[0090] FIG. 9 suggests variously shifted positions of the rotation
axis 30a of the damper blade 30 and air flow path dividing means
70.
[0091] As shown in FIG. 9, in the present invention, it is possible
to shift the rotation axis 30a of the damper blade 30 and the air
flow path dividing means 70 upward or downward from the center K of
the duct, but also it is possible to have rotation axes K1 and K1'
which are shifted forward and backward, respectively, from the
center K of the duct.
[0092] Also, it is possible to have rotation axes K2 and K2' which
are shifted forward and backward, and also upward and downward,
respectively. With the rotation axis 30a of the damper blade 30 and
the air flow path dividing means 70 shifted in combination from the
center K of the duct, the air flow path blocking means 80 can
accordingly be fixed to the duct 10 in various positions and
structures.
[0093] In addition, the present invention is applicable also to a
duct 10 having a rectangular cross-section in addition to a
circular cross-section.
[0094] FIG. 10 illustrates another variation of the preset
invention.
[0095] The variable air volume control apparatus 1'' according to
the present invention includes the damper blade 30 disposed
rotatably to open or close the air flow path inside the duct 10,
and the actuator 40 for rotating the damper blade 30.
[0096] Also, the variable air volume apparatus 1'' includes an air
flow path expanding means 100 for expanding the air flow path in
accordance with the open angle of the damper blade 30 as the damper
blade 30 is opened. The air flow path expanding means 100 expands
and compensates the air flow path such that the air flow path,
which was opened by a function of "1-COS .theta." at a small open
angle, is now opened in proportion to the opening ratio.
[0097] That is, the air flow path expanding means 100 of the
present invention has a curved surface 110, which compensates for
an opened area of (.theta./90)-(1-COS .theta.), and accordingly, at
a low opening ratio, i.e., 0% to 30%, the damper blade is opened at
an open angle of .theta./90.
[0098] Here, .theta. is an open angle of the damper blade 30 from
the closed position of the damper blade 30.
[0099] In addition, the air flow path expanding means 100 is a ring
structure 112 that is installable on an inner surface of the duct
10, having an inner circumference the same as the circumference of
the damper blade 30.
[0100] In addition, the ring structure 112 preferably has a
circular inner periphery or alternatively, an oval inner periphery
in which the horizontal diameter, i.e., the axis of the damper
blade is larger than the vertical diameter thereof.
[0101] In addition, the air flow path expanding means 100 may be
formed by deforming the inner side of the duct 10 or by deforming
an outer side of the duct, rather than using a ring structure 112
described above.
[0102] In addition to the air flow path expanding means 100, the
present invention further includes the air flow path dividing means
70 which divides the air flow path of the duct 10 at an air inlet
side into an upper region S1 and a lower region S2 with respect to
a rotation axis 30a of the damper blade 30, exerting resistance to
air flow between a portion of the damper blade 30 biased toward the
air inlet side and the air flow path dividing means 70.
[0103] The variable air volume control apparatus 1'' having both
the air flow path expanding means 100 and the air flow path
dividing means 70 exhibits the open area ratio and the air volume
change ratio with respect to the opening ratio as shown in FIG.
11.
[0104] The open area ratio curve (a') obtained by the variable air
volume control apparatus 1'' of the present invention is
substantially more in direct proportion to the opening ratio curve
(c) at a low opening ratio (0% to 30%) than the open area ratio
curve (a) of the conventional variable air volume control
apparatus.
[0105] As described above, when the damper blade 30 is opened in an
arbitrary angle .theta. from the position of blocking the air flow
path, for example, when the open angle .theta. is opened in
9.degree. (opening ratio of 10%), the air flow path expanding means
100 expands and compensates an opened area of the air flow path by
9/90-(1-COS 9.degree.). When the damper blade 30 is gradually
opened to have an open angle .theta. of 27.degree. (opening ratio
of 30%), the air flow path expanding means 100 expands and
compensates the air flow path by 27/90-(1-COS 27.degree.),
increasing the air volume.
[0106] As described above and shown by curve (a') in FIG. 11, when
the opening ratio of the air flow path expanding means 100 is 30%
or less, i.e., the open angle .theta. of the damper blade 30 is
27.degree. or less, the open area ratio is in direct proportion to
the opening ratio, thereby resulting in significantly improved
linear characteristics.
[0107] Therefore, when the opening ratio is from 0% to 50%, the
open area ratio is in direct proportion to the opening ratio,
thereby resulting in improved linear characteristics of the air
volume change ratio with respect to the opening ratio. This allows
more accurate and precise adjustment of the air volume.
[0108] On the other hand, when the opening ratio is 50% or more,
the air volume change ratio has improved linear characteristics
with respect to the opening ratio due to the air flow path dividing
means 70, enabling more accurate air volume control. This is
because the air flow is blocked from the upper region S1 to the
lower region S2 due to the closed space P2 formed by the air flow
path dividing means 70, causing resistance to the air flow in the
upper region S1 of the air flow path dividing means 70. Therefore,
the air overflow at a high opening ratio, i.e., 50% or more of the
damper blade 30, is effectively suppressed as shown by curve
(e).
[0109] Therefore, according to the variable air volume control
apparatus 1'' of the present invention, the open area ratio is
improved with respect to the opening ratio at the opening ratio of
50% or less of the damper blade 30 due to the air flow path
expanding means 100. Thereby, the air volume change ratio with
respect to the opening ratio is improved to have linear
characteristics. On the other hand, at the opening ratio of 50% or
more, the air overflow is effectively suppressed by the air flow
path dividing means 70, thereby preventing excessive air flow.
[0110] As a result, the variable air volume control apparatus 1''
having both the air flow path expanding means 100 and the air flow
path dividing means 70 according to the present invention yields
the air volume change ratio curve (f) shown in the dotted line in
FIG. 11. Thus, the air volume change ratio is closely approximate
to the opening ratio curve (c) in the entire range of the opening
ratio, i.e., 0% to 100%. This enables more accurate and precise air
volume control in accordance with the opening ratio.
[0111] According to certain embodiments of the present invention
set forth above, the air overflow occurring at high opening ratio
of the damper blade is effectively suppressed through simple
structural improvements, thereby enabling accurate and precise air
volume control.
[0112] Moreover, a certain embodiment of the present invention
adjusts the air volume change ratio to be more approximate to the
opening ratio of the damper blade, enabling more accurate and
precise control of air volume.
[0113] Furthermore, according to a certain embodiment of the
present invention, the variable air volume control apparatus has
both the air flow path expanding means and the air flow path
dividing means to more accurately and precisely control the air
volume in proportion to the opening ratio in the entire range of
the opening ratio.
[0114] The present invention has been explained and illustrated
with specific embodiments. The invention may, however, be embodied
in many different forms and should not be construed as limited to
the embodiments set forth herein. While the present invention has
been shown and described in connection with the preferred
embodiments, it will be apparent to those skilled in the art that
modifications and variations can be made without departing from the
spirit and scope of the invention as defined by the appended
claims.
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