U.S. patent number 3,921,900 [Application Number 05/482,699] was granted by the patent office on 1975-11-25 for automatic, temperature responsive damper assembly.
Invention is credited to James D. Cole.
United States Patent |
3,921,900 |
Cole |
November 25, 1975 |
Automatic, temperature responsive damper assembly
Abstract
A pivoted, split butterfly vane, damper assembly provided with
an automatic temperature responsive actuating means for opening and
closing the damper vanes in response to temperature changes useable
primarily with turbine ventilators in buildings is disclosed. A
temperature sensitive bellows element positioned beneath the damper
vanes actuates a pivoted lever to cause opening and closing of the
damper vanes over a predetermined range of temperatures. The free
end of the pivoted lever terminates in an upwardly extending arm,
the arm being provided with vane engaging fingers having sloped
camming surfaces with, in the preferred embodiment, the fingers
having cosine curve shaped camming surfaces for controlling the
rate of opening of the damper vanes over the selected temperature
range and for providing protection for the damper assembly should
the temperature range be exceeded.
Inventors: |
Cole; James D. (Austin,
TX) |
Family
ID: |
23917083 |
Appl.
No.: |
05/482,699 |
Filed: |
June 24, 1974 |
Current U.S.
Class: |
236/93R; 236/99R;
137/601.17; 137/601.05; 236/99J; 251/251 |
Current CPC
Class: |
F24F
11/76 (20180101); F16K 1/223 (20130101); G05D
23/123 (20130101); Y10T 137/87442 (20150401); Y10T
137/87531 (20150401) |
Current International
Class: |
F24F
11/04 (20060101); F24F 11/053 (20060101); F16K
1/22 (20060101); G05D 23/12 (20060101); G05D
23/01 (20060101); G05D 023/02 () |
Field of
Search: |
;137/601
;251/212,251,298 ;236/49,93,99 ;98/85,116,41R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dority, Jr.; Carroll B.
Assistant Examiner: Capossela; Ronald C.
Attorney, Agent or Firm: Jones, Tullar & Cooper
Claims
I claim:
1. An automatic temperature responsive damper assembly for use
within a ventilating conduit, said assembly comprising:
at least two movable vanes carried within said conduit, each of
said vanes being movable between a generally horizontal closed
position and a generally vertical open position in response to
temperature changes in said ventilating conduit;
a temperature responsive drive assembly mounted on a bracket within
said conduit beneath said vanes, said drive assembly being movable
in response to temperature changes in said ventilating conduit;
a lever positioned in said conduit and located between said drive
assembly and said vanes, said lever being pivotably connected at a
first end to said bracket, and being provided at a second end with
at least one vane engagable finger;
means to communicate said movement of said drive assembly to said
lever; and,
a camming surface for each of said movable vanes on said vane
engagable finger, each of said camming surfaces slidably contacting
a corresponding one of said vanes to move said vanes between said
open and closed positions in response to said movement of said
drive assembly.
2. The apparatus of claim 1 wherein said vanes are movable about a
substantially common axis, said axis lying generally in the center
of said conduit.
3. The apparatus of claim 2 wherein said drive assembly is an
expansible and contractable bellows assembly, said bellows assembly
expanding and contracting in response to said temperature changes
in said conduit.
4. The apparatus of claim 3 wherein said means to communicate said
movement of said bellows assembly to said lever comprises a leg
adjustably secured to said lever adjacent said lever's first end
and further wherein said leg engages said bellows assembly whereby
movement of said bellows causes movement of said lever.
5. The apparatus of claim 4 wherein said camming surfaces are in
the shape of a cosine curve.
6. The apparatus of claim 5 further wherein each said vane is
secured to a separate hinge rod, each of said rods passing through
said conduit and having an indicator portion exterior of said
conduit whereby the position of said vanes in said conduit is
indicated by the position of said indicator means portions of said
hinge rods.
Description
FIELD OF THE INVENTION
The present invention is directed generally to a ventilation
conduit damper assembly for use primarily with a turbine
ventilator. More specifically, the present invention is directed to
such a ventilation damper assembly provided with automatic,
temperature responsive, actuating means whereby the amount of
movement of the damper vanes, over a preselected temperature range,
is controlled.
A pivoted, split butterfly vane, damper is provided within a
ventilating conduit with the damper vanes being disposed
horizontally in their closed position. A temperature sensitive
bellows assembly is positioned beneath the damper vanes and upon
expansion or contraction of the bellows due to temperature change,
a lever, pivoted at one end, is caused to move. A bifurcated or
generally Y shaped arm is carried at the free end of the lever and
is provided with fingers having camming surfaces which engage the
damper vanes, thus causing the damper to open or close with a
change in temperature. In the preferred embodiment, the fingers'
camming surfaces are of a cosine curve shape and cause rapid
initial opening of the damper in response to a small temperature
change, and also provide that, upon the opening of the damper to
its full open position, additional movement of the arm may be had
without damage to the assembly. Since the bellows and the camming
surface shape may be changed, a damper is provided which allows for
operation over various preselected ranges of temperatures.
DESCRIPTION OF THE PRIOR ART
Dampers for use in conduits are generally known and are utilized,
for example, in stoves, fireplaces, furnaces and the like.
Typically these assemblies consist of a movable vane or vanes which
are positionable to control the amount of air flow through the
conduit within which the damper is placed. In many of these
installations, the damper is either open or closed with this
position selection being done manually. Dampers are additionally
often used in conjunction with ventilating systems in homes and
similar buildings when it is desired to provide ventilation for a
portion of the building.
In some areas of the country where rather hot weather is
experienced during at least a portion of the year, it is often
desirable to provide a means for ventilating a portion of a
building, typically an attic or the like. This ventilation is often
provided by using a turbine air ventilator of a known type in which
wind causes the turbine to turn and causes air to be, in effect,
pumped out of the area provided with the ventilating conduit.
While turbine ventilation systems are quite effective in promoting
air flow, they have, in the past, suffered from the lack of an
effective automatic means to control the amount of air removed.
Obviously the air flow should be at a maximum during hot weather
when the temperature in the area to be ventilated is high, but just
as obviously the ventilation should be much less when the
temperature in the area to be ventilated is lower. Constant
ventilation, even in periods of cool temperatures, causes an
unnecessary loss of heat and a consequent increase in heating
costs. While this problem of present ventilation systems is
recognized, the attempted solutions have been less than
satisfactory.
Although some type of adjustable damper is desirable, in a number
of instances no such adjustable flow control means has been
provided. When a damper is provided, it often is of the type where
the position of the damper means is adjustable by, for example, a
manual movement of the vanes. Since the space to be ventilated,
typically an attic, is often inaccessible, the homeowner is not apt
to manually adjust the damper as often as he should to provide for
efficient ventilation in hot periods or for retention of heated air
during cold periods. Other adjusting means such as chain pulls,
elongated adjusting rods and the like have been provided, but again
either these are difficult to use or else the homeowner simply
forgets to change the damper position. Hence the damper is open
when it should be closed or closed when it should be open so that
it is ineffectual in performing its intended function. With the
increasing cost of power used for heating and air-conditioning, it
becomes readily apparent why an automatic damper system should be
utilized in conjunction with ventilation systems.
Unfortunately, the few prior automatic adjustable dampers which
have been contemplated or manufactured have been unable to perform
their desired function in an effective, economical manner. These
automatic controls, when available, have suffered from high cost,
undependability, a failure to provide simple means to vary the
range of temperature over which they operate the damper, and a
propensity to become damaged or disabled in cases of temperature
fluctations in excess of those designed for. This lack of
dependability, high cost and incidence of damage to the device by
abnormal temperature fluctations has combined to limit the use and
acceptance of automatic damper control systems in home ventilating
systems and the like.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to provide
an automatic damper assembly for use in a home ventilating
system.
A further object of the present invention is to provide an
automatic damper which requires no attention from the
homeowner.
Yet another object is to provide an automatic damper assembly which
is simple in operation and low in cost.
A still further object of the present invention is to provide an
automatic damper assembly for use with a turbine ventilator wherein
the operating temperature range may be preselected and further
wherein temperatures in excess of those preselected will not
adversely affect the assembly.
The damper assembly of the present invention is comprised generally
of a split butterfly vane damper positioned in an air flow conduit.
Temperature sensitive bellows are positioned below the damper vanes
and expand or contract in accordance with temperature changes. A
lever is positioned between the bellows and vanes and is pivoted at
one of its ends. The free end of the lever carries an upwardly
extending bifurcated or generally Y shaped arm provided with vane
contacting fingers having sloped camming surfaces. In the preferred
embodiment, these fingers have generally cosine curve shaped
camming surfaces which engage the damper's vanes and cause movement
thereof in response to expansion or contraction of the
temperature-sensitive bellows.
As previously discussed, it is desirable to provide ventilation for
enclosed spaces such as buildings or attics during at least a
portion of the year. The present damper, where used in conjunction
with a conventional turbine ventilator, provides such ventilation
and additionally, and more importantly, provides an automatic
control such that air flow is controllable in response to ambient
air temperatures, thereby insuring that adequate ventilation is
provided when necessary, yet preventing the unwanted flow of air
when the ambient temperature is below a preset level. Thus, heating
costs are reduced since the system is closed during cold
weather.
The damper of the present invention is contained within the air
conduit and hence is mountable in an existing line with no
additional exterior space required. This feature is of particular
benefit in areas where there is insufficient space for external
controls or linkages.
Due to the completely automatic nature of the present damper
assembly, no attention is required on the part of the homeowner.
The damper operates automatically over the preselected temperature
range, opening and closing in response to temperature changes, thus
assuring even the most forgetful homeowner that proper ventilation
is taking place. The fully automatic nature of the present damper
assembly also eliminates the need for mechanical adjusting means
such as the chains, levers and rods discussed previously. This
allows the apparatus to be positioned at the most advantageous
portion of the flow conduit with no necessity for providing access
for any mechanical or manual adjusting means.
The temperature-sensitive bellows which cause the movement of the
lever and hence the damper are well known and can be selected to
operate over any desired temperature range. A bellows with the
desired temperature sensitivity is chosen and installed in the
assembly to cause the damper to open and close over the desired
range. An abnormally low temperature will not adversely affect the
damper assembly since once the temperature falls below the range of
the bellows, further temperature decreases will have no effect.
Similarly, an abnormally high temperature will not harm the damper
mechanism since the camming surfaces on the damper vane contacting
fingers are so shaped as to slide over the face of the vanes once
the vanes are in their fully opened position. Hence the assembly,
unlike previously attempted automatic dampers, is efficient,
reliable, unharmed by temperature fluctuations in excess of those
designed for, completely automatic, capable of insertion into
existing conduits, and low in cost.
BRIEF DESCRIPTION OF THE DRAWINGS
While the novel features of the present invention are set forth
with particularity in the appended claims, the invention will be
understood more fully and completely from the detailed description
of a preferred embodiment as set forth hereinafter, and as seen in
the accompanying drawings in which:
FIG. 1 is a schematic elevation view of a portion of a building
with the ventilation system and automatic damper assembly in
place;
FIG. 2 is a side elevation view of the automatic damper assembly of
the present invention with a portion of the conduit removed;
FIG. 3 is an end elevation view of the apparatus, partly in
cross-section, taken along line 3--3 of FIG. 2; and,
FIG. 4 is an elevation view of a preferred shape of the vane
engaging fingers.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to FIG. 1, there is shown generally at 10 a
ventilation system utilizing the automatic damper assembly of the
present invention. As may be seen, system 10 is comprised of an air
conducting conduit 12 passing through the roof 14 of a building 16.
Conduit 12, which is provided with a suitable sealing means
generally indicated at 18 at its point of passage through roof 14,
carries, at its exterior portion, a turbine ventilator 20 of
conventional construction. Since these ventilators are well known
it will be sufficient to indicate that ventilator 20 is provided
with a number of vertical slats 22 which cause the assembly to
rotate under the influence of wind, and to act as an air pump.
Conduit 12 carries, at an exterior portion thereof, an automatic,
temperature actuated, damper assembly 24 in accordance with the
present invention. Although damper assembly 24 is shown as being
placed in conduit 12 exteriorly of roof 14, it may alternatively be
placed interiosly thereof if desired. While damper assembly 24 will
hereinafter be described as being positioned in a circular air
conduit 12, it will be understood that other similar conduit shapes
such as square or rectangular may also be utilized with appropriate
modifications being made to damper assembly 24.
As may be seen more completely in FIG. 2, damper assembly 24 is
carried within a section of circular air conduit 12, such conduit
being preferably of conventional galvanized sheet metal, with
damper assembly 24 being comprised generally of a movable vane
portion 26, and a temperature actuated vane opening and closing
assembly 28.
Movable vane assembly 26, as seen in FIGS. 2 and 3, consists of a
pair of movable vanes 30 and 32 with each such vane being in the
shape of a semi-circular disc and being formed preferably of
aluminum sheet metal. Each vane 30 and 32 is secured, along a
diametral portion 34 and 36 respectively thereof, to a hinge rod 38
and 40 respectively. Each of these hinge rods 38, 40 pass generally
through the center of conduit 12 and are free to rotate. Each hinge
rod 38, 40 is provided, at its segment external to conduit 12, with
a vane position indicator portion 42, such indicator being a flag
or painted portion (not shown) or the like and serving to indicate
the relative position of the vane carried by each such rod. Vanes
30 and 32 may be securely affixed to hinge rods 38 and 40 by any
acceptable means such as screws (not shown) so long as vanes 30, 32
move with rods 38, 40. While, in the preferred embodiment, vanes 30
and 32 are shown as being separate and each carried by separate
hinge rods 38 and 40 respectively, it will be understood that
various other hinge means such as piano hinges and the like may be
utilized and that both vanes may be hinged together so long as each
vane is capable of pivotal movement about its diametral
portion.
A vane stop piece 44 is affixed to the interior of conduit 12 by,
for example, a screw 46. Vane stop 44 is positioned above hinge
rods 38 and 40 and between vanes 30 and 32, as seen in FIG. 3, to
insure that the vanes do not open past vertical, thereby preventing
the vanes from becoming stuck in their full open position. A means
such as inwardly extending screws 48 and 50, as seen in FIG. 3, is
also provided to insure that vanes 30 and 32 do not travel past a
horizontal position when in their closed mode. Again, it will be
understood that alternative vane stops may be utilized with, for
example, piece 44 being replaced by spaced screws or the like and
with screws 48 and 50 being replaced by inwardly extending lips or
the like.
Automatic opening and closing of vanes 30 and 32 is, as previously
indicated, afforded by temperature actuated vane opening and
closing assembly 28. As illustrated in FIGS. 2 and 3, vane opening
and closing assembly 28 is carried within conduit 12 and is
disposed generally beneath vanes 30 and 32. A generally U-shaped,
upwardly opening bracket 52 is positioned beneath hinge rods 38 and
40 and parallel thereto. This bracket, which is affixed, at its
ends, to conduit 12 by any suitable means such as, for example,
screws 54 and 56, carries thereon a movable vane actuating lever 58
and a temperature sensitive drive assembly 60, as will now be more
fully discussed.
Vane actuating lever 58 which, as may be seen in FIGS. 2 and 3, is
of generally channel shape, is pivotally connected at a first end
62 thereof to bracket 52, and has a free end 63. This pivotal
connection may be of any conventional type and is shown in the
preferred embodiment as being a conventional cotter pin 64 which
passes through bracket 52 and lever 58. It will be noted that, as
shown in FIG. 3, lever 58 is of slightly less width than is bracket
52 so that lever 58 will be capable of being disposed within
bracket 52 when lever 58 is in its rest position.
Again as shown in FIGS. 2 and 3, an adjustable lever actuating leg
66 is carried by lever 58 adjacent the lever's pivoted end 62 and
above the center of bellows assembly 60. In the preferred
embodiment, leg 66 is shown as being comprised of a screw 68
provided with a rounded heat 70 and two adjusting nuts 72 and 74
carried above and below the web portion of lever 58. Head 70 rides
on an upper surface 76 of drive assembly 60, with screw 68 passing
through a suitable aperture (not shown) in bracket 52 so that
expansion or contraction of drive assembly 60 will cause movement
of leg 66 and hence movement of lever 58. Since screw 66 is
provided with adjusting nuts 72 and 74, the position of screw head
70 may be varied thereby varying the point at which leg 66 will be
caused to move by expansion of drive assembly 60.
Drive assembly 60 is, as seen in FIGS. 2 and 3, carried by a
supporting member 78 affixed to the underside of bracket 52 by
screws 80, 82 or by any other conventional means. Assembly 60 is
comprised of any conventional temperature sensitive drive means
with, in the preferred embodiment, two bellows elements 84 and 86
being provided. Each of these bellows elements 84 and 86 is
generally disc-shaped and both are so constructed that a change in
temperature will cause them to expand or contract. Lower bellows
elements 86 is provided with a downwardly extending bolt 88 which
passes through a hole (not shown) in supporting member 78 so that
bellows assembly 60 may be affixed thereto by means of a nut 90.
Upper face 76 of upper bellows element 84 is carried adjacent the
aperture (not shown) in bracket 52 and is contacted by the screw
head portion 70 of leg 66. It will be understood that any of a
number of temperature sensitive means may be utilized in assembly
60 so long as the expansion and contraction thereof is predictable
over a given temperature range.
A vane engaging arm 92 is carried at the free end 63 of lever 58,
as may be seen in FIG. 2. Arm 92 is secured to lever 58 by any
conventional means such as screws 94. As shown more clearly in
FIGS. 3 and 4, arm 92 is comprised of two upwardly extending,
spaced fingers 96 and 98 carried by a flat base plate 100. Fingers
96 and 98 have generally parallel inner edges 110 and 112 which are
provided, at their upper inner edges, with sloped camming surfaces
102 and 104 respectively. These camming surfaces are so shaped that
the space between fingers 96 and 98 increases with an increase in
distance from flat base plate 100. Camming surfaces 102 and 104
terminate at points 106 and 108, respectively, spaced from the base
plate 100 so that a constant space between edge portions 110 and
112 of the two fingers 96 and 98 is maintained over a portion of
the length of the fingers adjacent flat base plate 100. This
constant space is sufficient, as illustrated in FIGS. 3 and 4, to
allow the passage of the diametral portions 34 and 36 of vanes 30
and 32 therebetween when the vanes approach a vertical position, as
limited by stop 44. This insures that, even if lever 58 and hence
fingers 96 and 98 move upwardly to a greater extent than planned
due to abnormal temperatures, vanes 30 and 32 will pass between the
fingers and will not be damaged. Should lever 58 and hence arm 92
move upwardly to an extent in excess of that necessary to fully
open vanes 30 and 32, a flat spring 113, secured to the free end 63
of lever 58 and extending outwardly therefrom as may be seen in
FIG. 2, will engage the diametral portions 34 and 36 of the vanes
and will tend to force lever 58 downward.
Camming surfaces 102 and 104 are shown, in FIG. 3, as being of a
constant slope, while in FIG. 4 they are shown at 114 and 116 as
having a generally cosine curve shape. The constantly sloped
surfaces of FIG. 3 provide essentially two points of contact, one
at the ends of the fingers and one at points 106 and 108 for each
of the vanes, the contact point shifting as the bellows moves
through the intended temperature range. The cosine curved camming
surfaces of FIG. 4 provide a continually changing point of contact
between each camming surface and its corresponding vane. The shape
of the cam surface provides a rapid initial opening with a
subsequent reduction in vane opening rate due to the decreasing
rate of change of slope of the camming surface. Additionally, since
the amount of force required to raise the vanes decreases as they
are raised, the cosine curve shape of the cam surface provides that
its point of contact is further from the vane's pivot point
initially, and moves inwardly during vane opening, thereby
providing a generally constant vane opening force which makes
maximum use of the bellows movement and allows the use of a smaller
assembly. While either camming surface may be utilized, depending
on the type of vane actuation desired, the cosine curved shape of
FIG. 4 is also preferred since it provides substantially point
contact between the camming surfaces 102 and 104 and the vanes 30
and 32 with a consequent reduction in friction in addition to the
constant opening force.
In operation, a bellows assembly 60, having predetermined expansion
characteristics over the anticipated temperature range to be
encountered, is selected and installed in the supporting member 78.
The depth of member 78 is such that it limits the amount that
bellows assembly 60 may expand as top surface 76 of assembly 60
will be limited in its upward movement by contact with the
underside of bracket 52. This insures that assembly 60 will not be
harmed by over-expansion due to excessively high temperatures
encountered, for example, in shipping. The section of conduit 12
which carries the automatic damper assembly 24 is positioned in a
desired location in the ventilation system with conduit section 12
being provided with corrugations 118 to facilitate such insertion.
The damper assembly 24 is so positioned that vanes 30, 32 are
substantially horizontal when in their closed position. Leg 66 is
adjusted to allow the vanes to close completely at the low end of
the temperature range. As the ambient air temperature starts to
rise through the preselected range, bellows assembly 60 expands,
thereby forcing leg 66 upward, as shown in FIG. 2. Upward movement
of leg 66 causes lever 58 to pivot about pivot point 64 and to
raise its free end 63, thereby causing camming surfaces 102 and
104, carried by fingers 96 and 98, to engage vanes 30 and 32
forcing them to pivot open on hinge rods 38 and 40. As the
temperature increases, the vanes continue to open until they are
limited by engagement with stop 44. Further upward movement of
lever 58 caused by temperatures in excess of the predetermined
range will not adversely affect vanes 30 and 32 due to the uniform
space maintained between the fingers.
As the ambient temperature decreases, bellows assembly 60 contracts
thus causing lever 58 to lower and hence lowering vanes 30 and 32.
Any tendancy of the vanes to stick in the open position is
prevented by stop 44, flat spring 113, and may also, as a practical
matter, be counteracted by the vibration caused in conduit 12 by
the action of the turbine 20. The vanes continue to lower to their
horizontal closed position where they may be held by screw stops 48
and 50, effectively preventing air flow through the conduit.
Alternatively, screws 48 and 50 may be eliminated and the spacing
between the vanes and lever 58 adjusted so that vanes 30 and 32 are
horizontally supported by arm 92 when lever 58 is in its lowered
position. A further decrease in the ambient temperature below the
preselected range has no adverse effect on the damper assembly
since it merely causes the bellows to contract further.
While a preferred embodiment of a fully automatic temperature
responsive damper assembly that is low cost, dependable, easily
installed and not affected by temperature fluctuations in excess of
those anticipated has been hereinabove fully described, it will be
evident to one of ordinary skill in the art that a number of
variations in, for example, the shape of the conduit, and hence the
shape of the vanes, the positioning of the assembly in the conduit
-- i.e. either interiorly or exteriorly of the building roof, the
materials used, the various fastening means utilized such as, for
example, self tapping screws or pop rivets, and the specific
bellows structure may be made without department from the spirit
and scope of the invention and that therefore the invention is to
be limited only the following claims.
* * * * *