Damper operator for use with air, smoke and fire dampers

A damper operator for use with a damper having a frame and a damper blade pivotally associated with the frame, which damper operator comprises a drive rod; a pair of lever arms which are pivotally associated with each and which extend between the drive rod and a pivoting mechanism associated with the blade of the damper; and a latching mechanism which extends between portions of each of the lever arms, and which permits selective engagement and disengagement between those portions of the lever arms, and accordingly, selective respective rotation of the lever arms, so that the blade of the damper can be urged toward a predetermined orientation.

BACKGROUND OF THE INVENTION 
The present invention relates generally to air, smoke and fire dampers, and 
more particularly, to a simplified operator for use in conjunction with 
such dampers. 
A variety of dampers have been developed for use in regulating the flow of 
air through a duct system, as well as for use in controlling the passage 
of fire or smoke through the duct system. Many duct systems are large 
enough to acccommodate relatively large, multiple blade-type dampers, 
which generally include a plurality of hinged blades disposed within a 
frame. The damper blades are journalled for rotation within the frame of 
the damper, so that the blades can be opened or closed as desired. 
Examples of such dampers may be found, for example, in my U.S. Pat. No. 
4,113,230, dated Sept. 12, 1978, and entitled "Rotating Blade Fire 
Damper"; and my U.S. Pat. No. 4,113,232, dated Sept. 12, 1978, and 
entitled "Smoke, Fire, and Air Control Damper With Stamped Blade." 
A variety of damper operators have been developed for use in regulating the 
positioning of the damper blades between their open and closed position. 
For example, the damper assemblies previously referred to incorporate an 
operator which generally comprises a series of brackets attached to each 
of the blades of the damper, and a connecting rod which is pivotally 
attached to each of the brackets, so that uniform articulation of the 
damper blades occurs in response to movement of the connecting rod. 
Movement of the connecting rod, and accordingly positioning of the damper 
blades, can then be regulated by any of a variety of control linkages, one 
example being the linkage shown in my U.S. Pat. No. 4,113,230. 
Often, it is important to provide a damper operator which is capable of 
automatically responding to an external stimulus, such as the smoke or 
heat of a fire, so that the blades of the damper can be opened or closed, 
as indicated, both quickly and positively, irrespective of their existing 
position. One operator which has been developed for this purpose may be 
found in my co-pending patent application Ser. No. 16,514, filed on Mar. 
1, 1979, and entitled "Quadrant Operator". The operator disclosed 
generally includes a shaft-type actuating means which is selectively 
interconnected with the connecting rod which is used to regulate movement 
of the damper blades by a releasing device. The releasing device permits 
operation of the damper between its open and closed positions during 
normal conditions, however, upon sensing a selected stimulus, such as heat 
or smoke, the releasing device is caused to disengage from the connecting 
rod, so that the damper blades can be urged toward a selected position by 
an appropriate biasing means. 
Such damper operators serve well to properly operate the damper in 
accordance with the ambient conditions present in the duct system. 
However, in order to permit the damper blades to be fully rotated between 
their open and closed position, such damper operators must generally 
rotate through an arc of approximately 90.degree., so that their rotation 
will permit full travel of the connecting rod between its terminating 
positions. This requires that a sufficient amount of space be provided in 
order to permit free rotation of the damper operator, as well as free 
movement of the connecting rod between is terminating positions. 
Providing sufficient space to accommodate such damper operators generally 
does not present a problem when relatively large dampers can be used. 
However, such damper operators often cannot be used in conjunction with 
relatively small dampers, for use in duct systems having relatively small 
cross-sectional dimensions. One method which has been used to overcome 
this difficulty is to incorporate a damper which is large enough to 
accommodate a conventionally sized damper operator into a duct system 
which has been suitably modified to accommodate the larger damper therein. 
This generally requires that the duct be enlarged at the position where 
the damper is to be installed, which leads to two major disadvantages. 
First, it is necessary to specially modify the duct system to accept the 
larger damper structure. This leads to increased installation costs, as 
well as increased labor. Second, it is often required that such dampers be 
installed within portions of the duct system which extend through the fire 
walls associated with a building. For this reason, it is often not 
possible to utilize a damper having a cross sectional dimension which 
exceeds that of the duct, since to do so would require enlargement of the 
opening in the fire wall which accommodate the duct system, which is 
undesirable and often not possible. 
It is therefore desirable to develop a damper operator which can be used in 
conjunction with smaller sized dampers, in order to permit such dampers to 
be installed within the duct system without having to modify or enlarge 
the duct system. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a damper operator is provided 
which includes a shaft-type actuator which engages the blade of the damper 
so that movement of the actuator causes damper blade rotation during 
normal operating conditions, when no fire or smoke is detected, but which 
releases the damper blade, freeing the damper blade for rotation to a 
selected position, when fire or smoke is detected. To do so, the actuator 
is provided with an articulating assembly which comprises a first arm 
attached to and extending outwardly from the drive rod associated with the 
actuator; a second arm, pivoted for rotation about the first arm and 
including means for engaging the damper blade at one end, and a latch at 
the other end; and a release mechanism extending between the first arm and 
the latch of the second arm. 
During normal operating conditions, the release mechanism is caused to 
engage the second arm, thus preventing rotation of the second arm about 
the first arm. As a result, rotational movement of the actuator is 
transmitted through to the damper blade, which causes its rotation. 
Controlled movement of the actuator thereby regulates the angular position 
of the damper blade. In the event that a fire, or other stimulus, is 
sensed, the release mechanism is caused to disengage the second arm, which 
permits the second arm to freely rotate about the first arm. This permits 
the damper blade to be urged toward a pre-selected orientation by 
appropriate biasing means. 
Accordingly, it is a primary object of the present invention to provide a 
damper operator which can be used in conjunction with relatively small 
dampers. 
It is also an object of the present invention to provide a damper operator 
which can be used with relatively small dampers and which permits the 
position of the damper blade to be regulated as desired during normal 
operating conditions, but which assures that the damper blade can be 
released, and urged to a selected position, when an appropriate stimulus 
is encountered. 
It is also an object of the present invention to provide a damper operator 
which is simple in construction and reliable in use. 
These and other objects will become apparent from the following detailed 
description, taken in conjunction with the following illustrations.

In the several views provided, like reference numerals denote similar 
structure. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Although specific forms of the invention have been selected for 
illustration in the drawings, and the following description is drawn in 
specific terms for the purpose of describing these forms of the invention, 
this description is not intended to limit the scope of the invention which 
is defined in the appended claims. 
FIG. 1 illustrates a damper 1 which has been provided with a preferred 
embodiment damper operator 2 in accordance with the present invention. The 
damper 1 is a small, single blade-type damper, which has been selected for 
illustrative purposes only, it being fully understood that the damper 
operator of the present invention can also be used with dampers having 
other sizes, shapes and constructions. The damper 1 selected for 
illustration in the drawings generally comprises a frame 3, and a damper 
blade 4 journalled for rotation within the frame 3. 
The frame 3 generally includes a top 5, a bottom 6, and two sides 7, which 
combine to form an enclosure for the damper blade 4. The dimensions of 
this enclosure are generally selected to substantially correspond to the 
dimensions of the duct into which the damper 1 is to be installed. 
Preferably, those portions of the periphery of the frame 3 which are 
adjacent the damper blade 4 include a flange 8 which extends inwardly 
toward the center of the damper 1. A similar flange 8 may also be provided 
along the remaining portions of the periphery of the frame 3, if desired, 
as illustrated in FIG. 1. 
The damper blade 4 generally includes a face 9, and a bracket 13 which is 
attached to and extends rearwardly from the face 9. The face 9 of the 
damper blade 4 is substantially planar and includes a centrally disposed 
hinge 10, and flanged edges 11, 12. The bracket 13 includes a 
substantially planar surface 14, one end of which is provided with a 
camming mechanism 15, and the other end of which is provided with a 
mounting surface 16. A variety of devices may be used as the camming 
mechanism 15, one example being the device illustrated in the drawings, 
which includes a ferrule 17 extending outwardly from the surface 14 of the 
bracket 13, and a lock-washer 18 and pin 19 extending through the ferrule 
17, to retain the ferrule 17 to the bracket 13. The mounting surface 16 
includes two portions which extend outwardly from the surface 14 of the 
bracket 13 to form a surface which contacts the planar face 9 of the 
damper blade 4, so that appropriate attachment means, such as the rivits 
20 illustrated, may be used to attach each portion of the mounting surface 
16 to the planar face 9 of the damper blade 4. 
The damper blade 4 is journalled for rotation within the frame 3 by a 
plurality of mounting brackets 21 associated with the flange 8 of the 
frame 3. Each mounting bracket 21 includes a hinge engaging element 24 
which extends outwardly from the sides 7 of the frame 3 and into 
engagement with the hinge 10 of the damper blade 4. In this manner, the 
damper blade 4 is permitted to freely rotate between a fully open and a 
fully closed position as illustrated. 
Orientation of the damper blade 4 within the damper 1 is controlled by the 
camming mechanism 15 operatively associated with the bracket 13, in a 
manner which will be more fully described hereinafter. In the fully open 
position, it is preferred that the damper blade 4 provide a minimum 
restriction to the air flow through the damper 1. This is assured by 
orienting the face 9 of the damper blade 4 so that it is substantially 
parallel to the air flow through the damper 1. In the closed position, it 
is preferred that the flanged edges 11, 12 of the damper blade 4 contact 
the flange 8 of the frame 3, to provide a sealed closure. In order to 
assure proper closure, while assuring free rotation of the blade 4 within 
the damper 1, one of the flanged edges 11 is directed inwardly toward the 
center of the damper 1 so that those portions of the face 9 of the damper 
blade 4 adjacent the flanged edge 11 are positioned adjacent inner 
portions 25 of the flange 8, while the other flanged edge 12 is directed 
outwardly from the damper 1 so that those portions of the face 9 adjacent 
the flanged edge 12 are positioned adjacent outer portions 26 of the 
flange 8. In this manner, the upper segment 75 of the face 9 of the damper 
blade 4 engages the outer portions 24 of the flange 8, while the lower 
segment 76 of the face 9 engages the inner portions 25 of the flange 8, 
providing a properly sealed enclosure. 
The damper operator 2 generally comprises a drive rod 29; a pair of lever 
arms 27, 28 which are pivotally associated with each other and which 
extend between the drive rod 29 and the camming mechanism 15 of the damper 
blade 4; and a latching mechanism 30 which extends between selected 
portions of each of the lever arms 27, 28. 
As is best illustrated in FIG. 3, the drive rod 29 extends transversely 
outwardly from a position adjacent the interior of the damper 1, through a 
support bracket 39, to a position located beyond the side 7 of the damper 
frame 3. The support bracket 39 includes a base 40, and opposing sides 41 
which engage the drive rod 29. The base 40 of the support bracket 39 is 
attached to the flange 8 of the damper frame 3, thus maintaining the drive 
rod 29 in its desired orientation. To prevent transverse movement of the 
drive rod 29 within the mounting bracket 39, a locking bearing 42 is 
located between the sides 41 of the mounting bracket 39, and around the 
drive rod 29. A set screw 43 can then be used to maintain proper 
engagement between the drive rod 29, and the locking bearing 42. 
The lever arm 27 includes a substantially planar surface 31 having a 
substantially cylindrical periphery, each end of which is provided with an 
aperture. A first aperture 32 has a diameter which substantially 
corresponds to the diameter of the drive rod 29. Upon assembly, the lever 
arm 27 is fixedly attached to the drive rod 29, so that rotation of the 
drive rod 29 will cause rotation of the lever arm 27. The second aperture 
33 is sized to accept an appropriate pivoting mechanism, such as the rivit 
34 illustrated, to pivotally attach the lever arm 27 to the lever arm 28. 
The lever arm 28 also includes a substantially planar surface 35, one end 
of which is provided with a longitudinally extending U-shaped slot 36 and 
the other end which is provided with a blade 37. The lever arm 28 is also 
provided with an aperture 38 for receiving the rivit 34 which pivotally 
connects the lever arms 27, 28 to each other. The slot 36 of the lever arm 
28 has a width which is preferably slightly larger than the diameter of 
the ferrule 17 of the camming mechanism 15. During assembly, the slot 36 
is positioned to engage the ferrule 17, so that rotation of the damper 
operator 2 causes rotational movement of the bracket 13 of the damper 
blade 4, thereby moving the damper blade 4 to its desired position. As the 
bracket 13 is rotated, the ferrule 17 is permitted to slide along the slot 
36 of the lever arm 28, thereby assuring free movement of the damper 
operator 2 and damper blade 4 with respect to each other. Although it is 
preferable to engage the ferrule 17 within a slotted enclosure such as 
that shown, it is also possible to allow the ferrule 17 to advance along 
an unenclosed, outer edge of the lever arm 28, if desired. 
The latching mechanism 30 regulates respective movement between the lever 
arms 27, 28. During normal operating conditions, the latching mechanism 30 
prevents the lever arm 28 from rotating with respect to the lever arm 27, 
so that rotation of the drive rod 29 operates the damper blade 4, as 
illustrated in FIGS. 2 and 3. When a selected stimulus is encountered, 
such as the heat or smoke of a fire, the latching mechanism 30 releases, 
permitting the lever arm 28 to rotate with respect to the lever arm 27, 
which permits the damper blade 4 to be urged toward a selected 
orientation, as illustrated in FIGS. 4 and 5. 
A variety of latching mechanisms 30 may be used to control respective 
movement between the lever arms 27, 28. One preferred latching mechanism 
which can be used for this purpose, as illustrated in FIGS. 1-5, is a heat 
actuated link of the type disclosed in my prior U.S. Pat. No. 3,889,314, 
dated June 17, 1975, the subject matter of which is incorporated herein by 
reference. Such a latching mechanism 44 generally includes a base plate 45 
having a notch 46 spaced away from and substantially parallel to the base 
plate 45, and a serpentine, bimetallic element 47, one end of which is 
attached to the base plate 45 and the other end of which is provided with 
a latch 48 which extends through the notch 46 to the base plate 45. For 
use in conjunction with the damper operator 2 illustrated in FIGS. 1-5, 
the base plate 45 of the latching member 44 is attached directly to the 
lever arm 27 using, for example, the rivits 49 illustrated. The latching 
mechanism 44 is positioned on the lever arm 27 so that the latch 48 and 
the notch 46 are aligned with portions of the blade 37 of the lever arm 
28. The blade 37 of the lever arm 28 is provided with an aperture 50 which 
is sized to receive the latch 48. 
Accordingly, during normal operating conditions, the latch 48 extends fully 
through the notch 46 to the base plate 45 of the latching member 44, so 
that the blade 37 of the lever arm 28 is positively engaged, preventing 
respective movement between the lever arms 27, 28. Since the element 47 is 
formed of a bimetallic material, when the element 47 encounters a source 
of heat, the element 47 will expand, which draws the latch 48 out of the 
aperture 50 of the blade 37. This releases the blade 37, thereby 
permitting the lever arm 28 to pivot with respect to the lever arm 27. 
This, in turn, frees the camming mechanism 15 associated with the damper 
blade 4, which permits the damper blade 4 to rotate within the damper 
frame 3. By attaching a spring 51 between an aperture 52 in the bracket 13 
and an aperture 53 the flange 8 of the damper frame 3, the damper blade 4 
is caused to move to its closed position. Closure of the damper blade 4 is 
limited by contact between the flanged edges 11, 12 of the damper blade 4 
and the flange 8 of the damper frame 3 as previously described. 
FIG. 8 illustrates one manner in which the damper illustrated in FIGS. 1-5 
can be installed in a duct 54. As illustrated, the duct 54 extends through 
a firewall 55. It is therefore desirable to position the damper 1 directly 
within those portions of the duct 54 which extend through the firewall 55, 
without having to modify the structure of the duct 54. The damper 1 and 
dampeer operator 2 of the present invention permit this to be done, 
irrespective of the height of the damper, since the damper operator 2 is 
capable of operating in small spaces. Installation is accomplished by 
positioning the damper 1 within the duct 54 so that the frame 3 of the 
damper 1 is positioned within the firewall 55, and so that the support 
bracket 39 for the drive rod 29 extends rearwardly from the firewall 55 as 
shown. In this manner, the damper structure is accommodated within the 
duct 54, without having to modify the duct, and the drive rod 29 is free 
to extend outwardly from the duct 54 without interfering with the 
installation. A drive arm 56 is then attached to the drive rod 29, so that 
the drive shaft 57 (or cable) of an actuator 58 can engage the drive arm 
56 at an appropriate pivot 59. 
During normal operating conditions, the latch 48 of the latching mechanism 
44 engages the blade 37 of the lever arm 28, so that the lever arms 27, 28 
are prevented from rotating with respect to each other. In this manner, 
rotation of the drive rod 29 causes rotation of the lever arms 27, 28, 
thereby rotating the damper blade 4 into a position regulated by operation 
of the actuator 58. This condition will continue until such time as a 
selected stimulus, such as the heat of a fire, is encountered. The 
presence of heat in the vicinity of the latching mechanism 44 causes the 
bimetallic element 47 of the latching mechanism 44 to expand, pulling the 
latch 48 from the aperture 50 in the blade 37 of the lever arm 28. This 
frees the lever arm 28 for pivotal movement with respect to the lever arm 
27. As a result, the damper blade 4 is drawn toward its closed position by 
the spring 51, thereby closing the damper and sealing the duct 54 with 
which it is associated, providing the function of a fire damper. 
The damper 1 remains in its closed position until it is reset, which can be 
accomplished as follows. When the source of heat is removed from the 
vicinity of the latching mechanism 44, the bimetallic element 47, and the 
latch 48, are returned to their original position, which causes the latch 
48 to advance through the notch 46 to the base plate 45. To reset the 
damper, the damper blade 4 may be manually rotated toward its open 
position, or the actuator 58 may be operated in a manner which urges the 
drive rod 29 and the lever arm 27 toward the position which those elements 
would normally assume to close the damper blade 4, until the lower edge 60 
of the blade 37 is brought into contact with the latch 48 of the latching 
mechanism 44. By providing the lower edge 60 with a sloping surface, the 
latch 48 is forced outwardly until the aperture 50 of the blade 37 is 
brought into alignment with the latch 48, whereupon the latch 48 will be 
urged into the aperture 50, preventing further respective movement between 
the lever arms 27, 28. The damper 1 is then ready to resume normal 
operation, as previously described. 
If desired, such a resetting function can also be provided by incorporating 
a reset arm (arm shown) into the damper operator 2 which is capable of 
rotating the blade 37 of the lever arm 28 into alignment with the latch 48 
as previously described. Such a reset arm may even be used to reset the 
damper operator 2 from a position external to the duct 54, if desired. 
Often, it is desirable to latch the damper blade 4 in its closed position, 
so that pressures which are created in the duct during the occurance of a 
fire cannot force the damper blade 4 open. In order to provide this 
function, a locking clip 68 may be used. The locking clip 68 is preferably 
formed of a bimetallic material and is preferably attached directly to the 
bottom 6 of the frame 2 using, for example, the rivits 69 illustrated. 
During normal operating conditions, the locking clip 68 extends along the 
bottom 6 of the frame 3, so that the locking clip 68 does not interfere 
with operation of the damper blade 4. However, when the heat of a fire is 
present, the locking clip 68 is caused to swing upwardly into the path of 
the damper blade 4, preventing it from being forced open. To enhance 
operation of the locking clip 68, it is preferred that the surface of the 
locking clip 68 be provided with two chamfers 70, 71. The first chamfer 70 
is relatively long and gradual, while the second chamfer 71 is relatively 
short and steep. The chamfers 70, 71 are provided to assure that the 
damper blade 4 closes over the locking clip 68, even if the locking clip 
78 has already partially extended into the path of the damper blade 4 
before it has closed. Of course, after the fire has subsided, the locking 
clip 68 will cool and retract to its original position, adjacent the 
bottom 6 of the frame 3, freeing the damper blade 4 for continued 
operation. 
It may therefore be seen that the foregoing damper 1 and damper operator 2 
serve well to satisfy the several objectives previously set forth. 
However, it may also be seen that these components can be modified without 
departing from the present invention. For example, the damper operator of 
the present invention may be used in conjunction with a variety of 
dampers, not just the damper 1 illustrated in the drawings. It is even 
possible for the damper operator 2 of the present invention to be used in 
conjunction with larger dampers if desired. However, this is considered to 
be less desirable since the damper operator 2 of the present invention 
does not provide the same mechanical advantage as the damper operators 
which are currently used in conjunction with larger dampers. 
The structure comprising the damper operator 2 of the present invention can 
also be modified, so long as a mechanism is provided for assuring 
selective pivotal rotation between the levers arms 27, 28 in response to a 
selected stimulus. One example of an alternative embodiment damper 
operator which may be used for this purpose is illustrated in FIGS. 6 and 
7. As before, the damper operator 61 includes a pair of lever arms 62, 63 
which are attached for pivotal rotation with respect to each other about 
the rivit 64, and which extend between the drive rod 29 and the camming 
mechanism 15 operatively associated with the damper blade 4 as previously 
described. The lever arms 62, 63 substantially resemble the lever arms 27, 
28, except for two differences. First, a hooked end portion 65 is 
substituted for the blade 37 which was associated with the lever arm 28. 
Second, a fusible link 66 is substituted for the latching mechanism 44 
previously described. The fusible link 66 is attached between the hooked 
end 65 of the lever arm 63 and a bolt 67 extending from the lever arm 62. 
As a result, during normal operating conditions, respective movement 
between the lever arms 62, 63 is prevented. When a source of heat is 
encountered, the fusible link 66 separates, which permits the lever arm 63 
to rotate with respect to the lever arm 62, thereby freeing the damper 
blade 4 for pivotal movement as previously described. To reset the damper 
operator 2 for renewed operation, a new fusible link 66 is installed, as 
previously described. 
Other latching mechanisms may also be used. For example, electrically 
operated devices may be used to provide for selective engagement between 
the lever arms of the damper operator, if desired. One way in which this 
may be accomplished is to provide the bimetallic element 47 of the 
latching mechanism 44 with an electrically heated pad, which permits 
operation of the latch 48 to be controlled in response to an electrical 
signal. An example of a mechanism which can be used for this purpose may 
be found in my U.S. Pat. No. 3,725,972, dated Apr. 10, 1973, and entitled 
"Fire Link and Method of Actuating Same", the subject matter of which is 
incorporated herein by reference. 
The damper 1 illustrated in FIGS. 1-8 has been provided with a damper 
operator which provides the function of a fire damper, one which closes 
upon detecting the presence of heat from a fire. However, the damper 
operator of the present invention may also be used to provide the function 
of a smoke damper if desired, one which fully opens upon sensing the 
presence of smoke. To do so, all that need be done is to provide the 
damper with a spring which urges the damper blade 4 toward a fully open 
position, and to suitably modify the release mechanism so that the lever 
arm 28, 63 is free to rotate to a position which the permits the damper 
blade 4 to be urged toward its fully open position by the spring 
associated with the damper. 
Lastly, throughout the foregoing description, the lever arms of the damper 
operator have extended between a rotatable damper blade and a rotatable 
drive assembly. This permits the damper to be operated as a control damper 
during normal operating conditions. However, it is not necessary for the 
damper operator of the present invention to provide the function of a 
control damper. It is also possible for the damp operator of the present 
invention to be used to provide only the function of a fire or smoke 
damper, if desired for a particular application. To do so, the end of the 
lever arm 27, 62 which is normally provided with the aperture 32 is 
fixedly attached to the damper frame 3, or a mounting bracket extending 
from the damper frame 3. Upon sensing the heat or smoke of a fire, 
operation of the damper operator would proceed as previously described. 
It will be understood that various changes in the details, materials and 
arrangement of parts which have been herein described and illustrated in 
order to explain the nature of this invention may be made by those skilled 
in the art within the principle and scope of the invention as expressed in 
the following claims.