Note: Descriptions are shown in the official language in which they were submitted.
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FLUIDIC FLOW SENSING AND CONTROL APPARATUS
BACKGROl~Nr OF THE I~IVE~TION
~he invention relates broadly to a system for
controlling the condition of air in a duct. More specifically,
the invention pertains to a control system which senses the
condition of air in a duct to regulate that condition. The
condition can be velocity, static pressure or the like.
In controlling a condition of a space, for example
temperature, dampers are sometimes used to regulate the amount
of conditioned air supplied to one or more zones. The damper
is regulated by a sensor, such as a thermostat. If there are
a plurality of zones involved, a damper is positioned to
control the amount of air supplied individually to each zone
and each damper has a different position depending upon the
temperature or condition of its associated zone. As the
condition in each zone changes, the position of the damper
changes which results in a variation in pressure and volume of
air delivered by the ducts to the zones. This variation in
pressure and volume of air delivered to the zones affects the
speed of response of the system.
In order to eliminate this problem, known prior
` art systems have used static pressure sensors to adjust the
-I position of the damper to maintain the static pressure in theduct constant. These known systems have, however, required
; 25 the use of complex and expensive control systems.
SUMM~RY OF THE INVENTIO~ -
The present invention regulates a condition of the
air in a duct by the use of a relatively simple and low cost
system. It utilizes an air condition sensor means, specifically
a velocity sensor, having a first nozzle for issuing a jet of
fluid and a second nozzle for receiving a portion of the fluid
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depending upon the condition in the duct, the first and second nozzles ~ :
arranged to directly measure the velocity of at least a portion of air from
the duct moving past the nozzles, fluid supply terminals, means to connect
the terminals to the first nozzle, a damper actuator attached to control the
damper, and second connecting means for connecting the second nozzle to the
damper actuator for varying the position of the damper depending upon the
velocity of said jet of fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention can be realized :
when the description below is read in accompaniment with the drawings in
which:
Figure 1 shows a velocity sensor for sensing the velocity of air
moving through a duct;
Figure 2 shows an arrangement for varying the set-point of the
sensor;
Figure 3 shows a velocity sensor for sensing static pressure in
a duct;
Figure 4 shows a self contained system utilizing a velocity sensor;
and :
Figure 5 shows another system for sensing the velocity of air
moving through a duct.
: DETAILED DESCRIPTION
In Figure 1, the air condition sensor 10 is a velocity sensor
comprising a nozzle 1 connected through a restriction 11 to a fluid source 2
issuing a jet of fluid, preferably air under pressure, towards a nozzle 3.
The nozzle 3 receives the portion of the fluid from nozzle 1 dependent upon
; the velocity of the air within a duct 4. Nozzle 1 issues a jet of fluid,
which may be either laminar or turbulent, towards nozzle 3 and nozzle 3
receives an amount of fluid from that jet dependent
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upon the condition of the air, in this case velocity of air, in
duct 4. As the velocity in~reases, the amount of fluid re-
ceived by nozzle 3 decreases and, as the velocity decreases, the
amount of fluid received by nozzle 3 increases.
~ozzle 3 is connected to a control chamber 12 of an
amplifier S. A flow chamber 13 of the amplifier 5 is separated
from control chamber 12 by a diaphragm 14 and is also con- ¦
nected to source 2 through a nozzle 23 and a restriction 15.
Flow chamber 13 has an exhaust port 16. A damper actuator 6
is connected downstream of restriction 15 and is used to position
damper 7 within duct 4 to regulate the air movement through
the duct. A thermostat 8, which may or may not be used, is
; located downstream of restriction ll-and may comprise a bimetal-
lic element 17 and a nozzle 18 for controlling the fluid supplied
to nozzle 1 dependent upon the temperature of a given space.
The air supplied through duct 4 is lssued through a diffuser 19
`7 into the controlled space in which thermostat 8 is located.
; The setpoint for the velocity of the air in duct 4
supplied to the controlled space may be adjusted in a number of
ways. One way of adjusting the setpoint is by regulating the
distance between nozzles 1 and 3. A second way is shown in
` Figure 2.
In Figure 2, an elongated container 20, having a slot
21 extending through the width thereof, has nozzle 1 extending
through one end of the container into slot 21 and the other
nozzle 3 extending through the other end of the container into
810t 21. A shield 22 regulates the amount of air passing through
810t 21 and, thus, ~etween nozzles 1 and 3.
A third way of adjusting the setpoint is to change
the velocity of the air issuing from nozzle 1.
With the setpoint predotermined, an increase in the
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velocity of the air flowing through duc~ 4 will divert a
larger percentage of the fluid issuing from nozzle 1. There-
fore, nozzle 3 will receive a smaller percentage of this fluid
and, thus, the pressure in chamber 12 will be reduced allowing
the diaphragm to move further off of nozzle 23 reducing the
pressure in line 24 to thereby drive actuator 6 to close damper
7 a corresponding amount. Upon movement of damper 7 toward a
closing position, the velocity, and thereby the amount, of air
flowing in duct 4 will be reduced.
If the velocity of air within duct 4 falls below the
setpoint, nozzle 3 will receive a greater percentage of the
fluid issuing from nozzle 1 thereby driving diaphragm 14 towards
nozzle 23 and raising the pressure in line 24. This raising of
the pressure will cause damper actuator 6 to drive damper 7 -
toward an open position to thereby increase the air movement
within duct 4.
During winter operation, if the conditioned space
needs additional heat, the bimetallic element 17 tends to close
towards nozzle 18 which raises the pressure of the fluid sup-
plied to nozzle 1. With the fluid issuing from nozzle 1 undera greater pressure, nozzle 3 receives a greater portion of
fluid to drive diaphragm 14 towards nozzle 23 and thereby
raise the pressure in line 24. When the pressure in line 24
increases, damper actuator 6 tends to open damper 7 an additional
25 ~ amount to supply more heated air to~controlled space. Thus,
for winter operation, an indirect acting thermostat is needed.
For summer or air conditioning operation, a direct
acting thermostat is needed such that as the tempera*ure in
the space increases, bimetallic element 17 tends to close
against nozzle 18 to raise the pressure of the fluid issuing
from nozzle 1. Thus, nozzle 3 will receive a greater portion
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of fluid tending to close ~iaphragm 14 against nozzle 23
raising the pressure in line 24 to tend to open damper 7 to
supply more cooled air to the conditioned space. The action
of the winter and summer thermostats can be reversed if
appropriate changes in the circuit are made.
In Figure 3, the air condition sensor is a static
pressure sensor comprising a nozzle 25 for issuing a jet of
fluid towards a nozzle 26. Air for delivery to a controlled
space is moved through a duct 27 under the control of a damper
28. An aperture 29 is located along the length of duct 27 for
~assing an amount of air over nozzles 25 and 26 of the sensor
dependent upon the static pressure within duct 27.
Nozzle 25 is connected to a source of fluid 30
through a restriction 31 and nozzle 26 is connected to a control
chamber 41 of an amplifier 320 The amplifier has a diaphragm
33 for separating control chamber 41 from a flow chamber 34.
Diaphragm 33 operates in conjunction with nozzle 35 to control
the pressure in line 36. Amplifier 32 also has an exhaust port
37. Line 36 is connected through a restriction 38 to source
30. A damper actuator 39 is connected downstream of restriction
38 and controls the position of damper 28. A thermostat 40 !
senses the condition of the space and controls the pressure
of the fluid supplied to the nozzle 25.
The operation of the system shown in Figure 3 is
basically similar to that shown in Figure 1. If the static
I"
pressure in duct 27 increases, a smaller percentage of fluid
; issuing from nozzle 25 is received by nozzle 26 which allows
diaphragm 33 to move away from nozzle 35 reducing the pressure
in line 36. This reduced pressure causes actuator 39 to move
damper 28 towards a closing position which reduces the static
pressure in duct 27.
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If the static pressure in duct 27 decreases, nozzle
26 receives a greater portion of the fluid issuing from nozzle
~: 25 tending to push diaphragm 33 against nozzle 35 increasing the
pressure in line 36. This increased pressure causes damper
actuator 39 to regulate damper 28 towards an open position to
increase the static pressure in duct 27.
The system shown in Figure 4 is a self contained
system which can be used in either of the system shown in
Figure 1 or Figure 3 or the like but~specifically shown with
10. respect to the system of Figure 1. An air condition sensor
comprises a nozzle 51 for issuing a jet of fluid and a nozzle
52 for receiving a portion of the jet of fluid depending upon
the condition of the air, in this case velocity, in a duct 53.
Nozzle 51 receives air from an inlet port 54 pointing upstream
in duct 53 which air is regulated ~y pressure regulator 55 and
supplied through a restriction g6. The air received by nozzle
52 is supplied to control chamber 57 of an amplifier 58.
The pressure within chamber 57 controls the position of a
diaphragm 59 of amplifier 58 with respect to a nozzle 60. .
Nozzle 60 is connected by a line 61 through a restriction 62 to .
. pressure regulator 55O A bellows 63 is connected downstream
of restriction 62 and drives a linkage 64 which is connected
to a damper 65 by a pivotal joint 66O The damper pivots around
point 67. A thermostat 68 is used to control the pressure
of the fluid or air supplied to nozzle 51 dependent upon the
temperature of the controlled space which is being supplied
by air through a defuser 69 located in duct 53. ~:~
When the velocity of air within duct 53 increases,
nozzle 52 receives a smaller percentage of air issuing from :',
nozzle 51 which allows diaphragm 59 to move away from nozzle 60
to decrease the pressure in line 61. This decreased pressure
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is transmitted to bellows 63 tending to collapse bellows 63
and move damper 65 towards a closed position reducing the air
movement or velocity through duct 53.
If, on the other hand, the air movement or velocity
through duct 53 decreases, nozzle 52 receives a greater per~
centage of the air issuing from nozzle 51 to tend to close
diaphragm ~ against nozzle 60. This closing increases the
i_
pressure in line 61 which tends to expand bellows 63 and
open damper 65 to increase the air movement or velocity through
duct 53.
The system shown in Figure 5 represents another method
of measuring the velocity of the air moving through a duct.
In this case, a tube 70 is located within a duct 71 and has a
plurality of openings 72 for receiving the air moving within
duct 71. The tube extends in a U-shape manner to the outside of
duct 71 and reenters duct 71 at point 73. A irst nozzle 74
is located within tube 70 for issuing a jet of fluid toward a
nozzle 75. Nozzle 74 receives fluid under pressure from a
source 76 through arestriction 77. The portion of fluid re- ¦
c`eived by the nozzle 75 is transmitted to a control chamber 78
of an amplifier 79O A diaphragm 80 of amplifier 79 has its
position relative to a nozzle 81 controlled by the pressure
within the control chamber 78. ~ozzle 81 is connected by a
d2r~0 ~r
line 82 through a restriction 83 to source 76. A ~Uk~rlgm
actuator 84 is connected downstream of the restriction 83 and
is used to control the position of a damper 85.
As the velocity of the air in duct 71 increases,
the velocity of the air within tube 70 increases and nozzle
75 receives a smaller percentage of the fluid issuing from
nozzle 74. ~he pressure in chamber 78 thus decreases allow-
ing diaphragm 80 to move away from nozzle 81, decreasing the .
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pressure in line 82 causing actuator 84 to close or tend to
close damper 85. The movement of damper 85 towards the.closing
position decreases the air velocity in duct 71.
On the other hand, if the air velocity within the
duct 71 decreases, the air velocity within tube 70 decreases
which causes nozzle 75 to receive a greater percentage of fluid
issuing from jet 74. The pressure in chamber 78 thus increases
tending to move diaphragm 80 against nozzle 81 to increase
the pressure in line 82 to cause damper actuator 84 to open
damper 85 increasing the air velocity through duct 71.
While in the forgoing specification the invention
has been described in considerable detail, it will be under-
stood that such detail is for the purposes of illustration
. and description and not for the purpose of limitation of the
invention which is defined in the appended claims.
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