Abstract:
A powered damper assembly in which closure of the damper blades is controlled by a powered actuator which can be powered by a pneumatic drive, an electric motor drive, or other suitable power source. The powered actuator moves a drive shaft attached to the damper blades which causes the damper blades to cycle between an open position and a closed position. The actuator can be controlled by sensors in a remote location, which allows the damper to be modulate it to set up pressure differentials and to be closed well in advance of oncoming smoke, fire, or other detected toxic fumes. The powered actuator maintains pressure on the damper blades to seal the damper tightly and prevent both smoke and fire from easily penetrating the damper. Optional remote placement of the sensors allow the damper be closed well in advance of the arrival of smoke, fumes, fire, etc. The remote sensors communicate with the dampers via direct wiring or, alternatively, via wireless transmission.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to air/smoke/fire dampers. In particular, it relates to dampers which can be controlled to be set and reset (i.e., closed and opened) locally or remotely under power, and which seal the damper under pressure when the damper blades are in the closed position, and which can modulate pressure levels to prevent smoke migration into designated non-smoking safety zones. It is also capable of setting normal operating building pressure differentials for cleaner air environments. 
     2. Background Art 
     Non-butterfly type dampers which can be closed automatically upon actuation by a heat-sensitive or other device are well-known in the art. Some such non-butterfly type dampers snap closed under either their own weight (i.e., gravity), or by mechanical force provided by springs. 
     As the art developed, external controls were devised to activate these dampers. Further, controls were also developed to cause the damper to be reset, that is, to be open in a ready position for heat responsive actuation in the event of fire or smoke conditions. A disadvantage of these prior art dampers is that they typically are activated by a separate device&#39;s exposure to the heat from a fire. As a result, they may disable the drive linkage making reactivation. Therefore, a substantial amount of smoke and even flames may pass through the damper before it is activated. It would be advantageous to have a damper system that could be activated well in advance of the fire or smoke to more effectively prevent either from passing through the damper. 
     An additional disadvantage associated with prior art systems is that these gravity or spring driven devices are slow to actuate. As a result, by the time the dampers are closed, substantial amounts of smoke, beat and even flames may have passed the damper and spread through the building. 
     In addition to problems caused by slow heat responsive closure, dampers which are then closed by gravity or spring driven devices do not always form an effective seal. As a result, even though the damper may be in the closed position, smoke and flames may penetrate the damper and spread to other parts of the building, causing property damage and personal injury. It would be desirable to have dampers that form an effective seal rather than merely temporarily contain either the fire or the progress of smoke, and to do so instantly, such that the potential damage from smoke, heat and flames is reduced. 
     While addressing the basic desirability of using dampers, the prior art has failed to provide a damper which can be powered closed well before advancing smoke and fire arrives, which creates an effective seal, and which can be sealed rapidly by a powered drive mechanism. 
     SUMMARY OF THE INVENTION 
     A powered damper assembly in which operation of the damper blades is controlled by a powered actuator. The powered actuator can be powered by a pneumatic drive, a electric owner controlled drive, or any other suitable power source. In one embodiment, the powered actuator is attached to the damper blades via a rotating shaft which is rotated by the powered actuator and which causes cycling of the damper blades to move between the open and the closed position, and be set in intermediate positions to set up controlled pressure environments by modulating the air flows. In another preferred embodiment, an electric motor powered actuator drives the shaft to cycle the damper blades between the open and the closed position. In another embodiment, the actuator can be self-controlled by a heat responsive device, which allows the damper to be closed by a spring or an automatically resetting motor control. The remote control system can communicate with the damper controls via a hard wired connection, or alternatively, via radio transmission. The powered actuation provides sufficient force to operate against heated air flow and to seal the damper tightly which in turn prevents both the smoke and fire from easily penetrating the damper. The butterfly blade design lends itself more readily to round or oval duct configurations, and this operating mechanism was developed to suit the “butterfly” damper design. The butterfly design also (when properly positioned) automatically uses the air fan or fire pressure to enhance the seal by pressing the ends of the pivoted blades against the frame. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cutaway side view of a preferred embodiment that shows a damper assembly with a pneumatic actuator in the open position. 
     FIG. 2 is a cutaway side view of the preferred embodiment of FIG. 1 that shows the damper assembly in the closed position. 
     FIG. 3 is a top plan view of the preferred embodiment of FIG. 1 showing the damper assembly in the closed position. 
     FIG. 4 is a cutaway side view of an alternative preferred embodiment that shows a damper assembly in the open position with an electric motor powered actuator. 
     FIG. 5 is a cutaway side view of the preferred embodiment of FIG. 4 that shows the damper assembly in the closed position. 
     FIG. 6 is a top plan view of the preferred embodiment of FIG. 4 showing the damper assembly in the closed position period. 
     FIG. 7A illustrates an alternative preferred embodiment in which a remote sensor in an air duct controls a powered damper via hard wired lines. 
     FIG. 7B illustrates another alternative preferred embodiment in which a remote sensor in an air duct controls a powered damper via radio communication. 
     FIG. 8 illustrates another alternative preferred embodiment in which an optional radiation blanket is installed on the surface of the damper blades. 
     FIG. 9A illustrates an alternative embodiment in which the edges of the damper blades are treated with a heat resistant sealant to provide a more effective seal. In this figure, the damper blades are shown in the open position. 
     FIG. 9B illustrates the embodiment of FIG. 9A with the damper blades in the closed position. 
     FIG. 10 illustrates an alternative preferred embodiment in which travel limit switches are placed on the actuator to automatically shut off the actuator at preset damper travel limits. 
     FIG. 11 illustrates another preferred embodiment in which a thermal locking mechanism is used to prevent the damper blades from being open in high temperature conditions. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a cutaway side view that shows a butterfly-type damper  10  of a type well known in the art, and which is used in conjunction with a powered actuator  30 . Such dampers  10  normally have two blades  16  which are shown in the open position. The blades  16  permit air to pass through damper  10  with minimal obstruction. Also shown in this view are blade stiffeners  12  which are attached to blades  16  and provide strengthening and rigidity to the structure of blades  16 . A principal advantage of the blade stiffeners  12  is that the rigidity and stability they add to the blades  16  provides a more consistent and secure seal when the blades  16  are moved to the sealed position. 
     Those skilled in the art will recognize that any suitable means can be used to secure the blade stiffeners  12  to the blades  16 . For example, they can be welded, riveted, screwed, etc. Further, the blades  16  and blade stiffeners  12  are angled in relation to one another, but they do not have to be set in any particular angle. In addition, any suitable material can be used to fabricate the blades  16  and the blade stiffeners  12 . The only requirement is that the material selected will perform satisfactorily in fire or smoke conditions. For ease of illustration, only two blades  16  are shown. However, those skilled on the art will recognize that the number of blades  16  can vary. 
     Also shown attached to the damper  10  is a powered actuator  30 . In this embodiment, the powered actuator  30  is a pneumatic actuator. Pneumatic drives are well known and have been used for a variety of devices. For example, pneumatic drives have been used to control radar antennas, power tools, etc. Powered actuator  30  is secured to the damper  10  structure by a side brace  34  which is fixedly attached at one end to the frame  18  of the damper  10  and fixedly attached at the other end to mounting blocks  36  on the powered actuator  30 . Between the powered actuator  30  and the damper  10 , there is an actuator support bracket  38  to help maintain the relative position between the powered actuator  30  and the damper  10 . The support bracket  38  also retains a shaft guide  54  which is used to guide a shaft  72  connected to the powered actuator  30 . Mounted to this shaft  72  is an angled bracket  14  which is either threaded thereto or has nuts fastened thereto and threaded in mating connection with shaft  72 . When the shaft  72  is rotated, the angled bracket  14  is moved axially thereon such that damper blades  16  pivot on pivot points  22 ,  24  and  26 . When the blades  16  pivot in this manner, they are moved from the open to the closed position. 
     Fixedly mounted to both the actuator bracket  14  and the support brackets  12  are members  20  which are connected at pivot points  22 ,  24 . If the shaft  72  is rotated in one direction, the actuator bracket  14  moves vertically upward, thereby exerting a force on the members  20  to move the blades  16  from the open position shown in FIG. 1 to the closed position shown below in regard to FIG.  2 . Likewise, when the shaft  72  is rotated in the opposite direction, the actuator bracket  14  moves downward, resulting in a force on the members  20  which moves the blades  16  from the closed position to the open position. Those skilled in the art will recognize that either a manual or automatic switch (not shown) may be used to open the damper  10  after it has been closed. 
     The preferred embodiments disclosed herein use a rotating shaft  72  in combination with an angled bracket  14  to control movement of the damper blades  16 . However, those skilled in the art will recognize that alternative drive mechanisms can be used to translate energy from the power actuator  30  to damper blade  16  motion. 
     The powered actuator  30  may be controlled by a heat responsive switch  32 , such as a conventional bi-metallic device, which is well known in the art, or any other suitable switch type. It may also be controlled by remote sensors, by manual activation, or by a computerized alarm system. Those skilled in the art will recognize that when remote activation is used, the damper  10  may be closed well in advance of the arrival of the fire or smoke. This provides significant advantages in terms of damage control by reducing the possibility that smoke or fire may penetrate the damper  10  before it is closed. More importantly, it may dramatically increase the safety of the people occupying the building because it will reduce the danger of smoke inhalation. Activation based on heat responsive devices may be preset to activate over a wide range of temperatures. For example, activation may be set from a low of 150 degrees Fahrenheit to as much as 400 degrees Fahrenheit. 
     FIG. 2 is a cutaway side view that illustrates the preferred embodiment of FIG. 1 with the damper blades  16  in the closed position. In this embodiment, when the powered actuator  30  is triggered, a valve (not shown) is opened and the damper  10  moves to a closed position under pressure provided by spring  56 . As can be seen, the force supplied through the powered actuator  30  forcibly presses the damper blades  16  against the damper frame  18  and holds the blades  16  in-place against any pressure build-up or differential pressure caused by fire, smoke, etc. In prior art systems, the gravity pressure provided by the systems may fail due to the buildup of pressure. This failure would result in the release of smoke or fire through the damper  10  and ultimately result in more extensive damage or injury to occupants of the building. As a result, powered closure of the damper blades  16  provides a more secure seal. Further, it allows the damper  10  to be closed from a remote location which allows earlier closure of the damper blades  16  well before arrival of smoke or fire. 
     Those skilled in the art will recognize that alternative methods of using pneumatic pressure can be used to close and seal the damper  10 . For example, spring  54  can be used to open damper  10  and damper  10  can be closed by pneumatic pressure controlled by a valve. A pneumatic system may use a pneumatic bellows  74  to drive the damper  10  to the desired open, closed, or intermediate position. The advantage of using the mechanical pressure of the spring to seal the damper  10  is that the mechanical pressure provided by the spring is less exposed to failure than a pneumatic system which may ultimately be damaged by fire and result in the opening of the damper  10 . 
     In FIG. 3, a top plan view is shown that illustrates the preferred embodiment of FIG. 1 with the blades  16  in the closed position. Blades stiffeners  12  are shown attached to the surface of blades  16 . As noted above, blades stiffeners  12  can be secured to blades  16  in any suitable manner. For ease of illustration, blades stiffeners  12  are shown aligned with actuator bracket  14 . However, though skilled in the art will recognize that actuator bracket  14  does not have to be aligned with blades stiffeners  12 . Further, only one blade stiffener  12  is shown attached to each damper blade  16 . However, the number of blade stiffeners  12  can vary. In this view, side brace  34  is shown attached to damper frame  18  and to the powered actuator  30  via mounting blocks  36 . 
     The damper  10  can also be automatically reset to the open position once temperatures have declined to an acceptable level. In the case of a damper  10  which is actuated by pneumatic pressure, an air input line controlled by the reset circuitry would be used to restore the pneumatic pressure. 
     In FIG. 4, a side cutaway view of an alternative preferred embodiment is shown. In this embodiment, the powered actuator uses electric motor  40  in place of the pneumatic actuator  30  which was used in the previous embodiment. Electric motor  40  is preferably a stepper motor which allows more precise position control of the damper blades  16 . Those skilled in the art will recognize that an air motor drive can be substituted for the electrical motor  40 . 
     When stepper motor  40  is activated, it rotates threaded shaft  28  which in turn moves angled bracket  14  which then moves damper blades  16  from an open to a closed position, or vice versa. In addition, the stepper motor  40  may be used to partially open or close the damper blades  16 . This is an advantage over the pneumatic actuator in that when the damper  10  is partially opened or closed under precision control of the stepper motor  40 , the air flow can be automatically controlled. In large buildings, the central computer can use remote sensors to regulate air flow throughout the building by independently controlling each damper  10 . 
     Stepper motor  40  may be attached to the damper frame  18  in the same manner that the pneumatic drive  30  of the previous embodiment was attached to damper frame  18 . The damper frame  18 , damper blades  16 , angled bracket  14 , and rotating shaft  28  do not need to be altered to use the stepper motor  40  of this embodiment. 
     In FIG. 5, a cutaway side view of the preferred embodiment of FIG. 4 shown with the damper blades  16  in the closed position. The stepper motor  40  has rotated threaded shaft  28  which in turn has raised angled bracket  14 . When angle bracket  14  is raised, members  20 , which are connected to angle bracket  14  at pivot points  24  and connected to damper blades  16  at pivot points  22 , pull damper blades  16  upward into the closed position. 
     FIG. 6 is a top plan view of the preferred embodiment of FIG.  4 . For ease of illustration, only two damper blades  16  are shown, and each damper blade  16  has only a single blade stiffener  12 . However, those skilled in the art will recognize that any convenient number of damper blades  16  can be used. In addition, the number of blade stiffeners  12  can also vary based on the size of the damper blades  16  and the strength of the material used to make them. As was the case with the previous embodiment, the angled bracket  14  does not have to be aligned with a blade stiffener  12 . The members  20  (not shown in his figure) can in fact be attached to blade stiffeners  12  or attached directly to the damper blades  16 . 
     The damper blades  16  may vary in size. As a practical matter, commercially available dampers typically have damper blade  16  sizes which vary from 16 to 24 inches. The two previous embodiments also show various details which are not critical to implementation of the invention. For example, members  20  are shown attached to rotatable pivot points  22  and  24 . However, a variety of attachment means can be used to secure members  20  to angle bracket  14 , to the damper blades  16  or to the blade stiffeners  12 . The preferred embodiments discussed so far illustrate a damper  10  with only two damper blades  16 . Those skilled in the art will recognize that any convenient number of damper blades  16  can be used. 
     Another aspect of the invention which is not critical to its implementation is the shape of the damper  10 . In the embodiment of FIG. 1, the damper  10  was illustrated as having a generally circular shape. In the embodiment of FIG. 4, the damper  10  was illustrated as having a generally rectangular shape. Control of the damper blades  16  is not dependent on the shape of the damper  10  which may be made in any convenient size or shape. 
     FIGS. 7A and 7B illustrate other preferred embodiments of the invention which remotely control operation of the powered damper  10 . In FIG. 7A, a remote sensor  42  is attached to damper  10  via hard wiring  44 . When remote sensor  42  detects heat or smoke  48 , it signals the power actuator  30  or  40  in damper  10  via wires  44 . Damper  10  then closes to prevent smoke  48  or fire from passing through damper  10 . By locating sensor  42  at a distance from damper  10 , damper  10  can close well in advance of the arrival of the smoke  48  or the fire. The ability to quickly close damper  10  before smoke on fire has passed through it is a significant advantage to the occupants of the building, because most personal injuries, and most deaths, are caused by smoke inhalation and not by the fire itself. 
     FIG. 7B illustrates another preferred embodiment of the invention. In this embodiment, the remote sensor  42  includes a radio transmitter  50 . When the sensor  42  detects smoke  48  or fire, it signals a receiver  52  which is attached to the damper  10 . The receiver  52  notifies power actuator  30  or  40  (depending on the embodiment) which turn closes the damper  10 . Those skilled in the art will recognize that while the term radio is used, any suitable wireless communications technology may be used to implement this function. This embodiment eliminates the signal wire  44 . This can be important because, depending on the location of a fire, the wiring may be damaged by fire before the remote sensor  42  detects the smoke  48  or fire. 
     All the previous embodiments discussed control of the dampers  10  by powered actuators  30  or  40  for use in fire control situations. Those skilled in the art will recognize that there are other reasons to control closure of dampers  10 . For example, in manufacturing environments workers may be exposed to toxic fumes from a wide variety of sources. Specialized sensors of any type may be used in the manner described previously to protect workers or occupants of building from dangerous fumes which may have nothing to do with fire. In the case of toxic fumes, early detection of the fumes, along with rapid and secure closure of the dampers  10 , can be extremely important in terms of safety. 
     In addition, all of the dampers  10  in a given location may be controlled by a central computerized system (not shown) that may use a variety of sensor types including fire, smoke, toxic fumes, vibration (e.g. for use an earthquake prone areas), etc. In addition to centrally controlling the dampers  10  in emergency situations, a central computer can also be used to control damper  10  operation for the purpose of regulating ventilation in a building during normal use. The embodiment which uses a stepper motor  40  is particularly useful for this activity since it allows for precision control of the damper blades  16 . 
     FIGS. 7A-B illustrate the damper  10  installed in a horizontally oriented duct  46 . However, the damper  10  can just as easily be installed in a vertically oriented duct  46 , or one that is oriented in a variety of directions. This provides an advantage over gravity powered or spring powered dampers in that the orientation of the damper does not affect its performance. 
     In FIG. 8, an optional radiation blanket  54  is illustrated. The radiation blanket  54  is attached to the surface of the damper blades  16 . The radiation blanket  54  insulates the damper blades  16  from heat and helps to prevent deformity of the damper blades  16 . The radiation blanket  54  can be fabricated from any suitable material which is resistant to the high temperatures found in a fire condition. 
     FIG. 9A illustrates an alternative preferred embodiment in which the edges of damper blades  16  have a layer of heat resistant sealant  62 . For ease of illustration, multiple adjacent damper blades  16  are shown. Each damper blade  16  is attached at a pivot point  58 , which is in turn attached to damper frame  18  along pivot point attachment line  60 . In this figure, the damper blades  16  are shown in the open position. Any suitable material can be used for the heat resistant sealant. However, in the preferred embodiment a commercially available silicone based sealant is used. 
     In FIG. 9B, the preferred embodiment of FIG. 9A is shown with the damper blades  16  in the closed position. For ease of illustration, pivot point attachment line  60  is not shown in this figure. When the damper blades  16  are rotated to the closed position, the heat resistant sealant  62  on adjacent damper blades  16  come in contact and form an improved seal to prevent smoke or heated air from passing through the damper  10 . Also shown in this figure is a segment of damper frame  18 . Attached to damper frame  18  is a surface  64  against which damper blades  16  can seal. Surface  64  is shown for illustrative purposes only. Those skilled of the art will recognize that surface  64  can be eliminated if damper blade  16  is constructed such that it seals directly against the wall of damper frame  18 . 
     FIG. 10 is a side view that illustrates an alternative preferred embodiment in which travel limit switches  66  are used to prevent the actuator  40  from attempting to move the damper blades  16  beyond preset damper blade travel limits. Travel limit switches  66  prevent damage to the damper blades  16  which may have otherwise occurred if the actuator  40  erroneously attempted to force the damper blades  16  beyond their intended travel limits. The travel limit switches  66  are electrically connected to the actuator  40  controls in the preferred embodiment. However, those skilled in the art will recognize that a variety of methods can be used to implement this switching system. 
     FIG. 11 illustrates another alternative embodiment in which a thermal locking mechanism is used to prevent the damper  10  from opening in high temperature conditions. This figure is a side cutaway view showing the damper blades  16  in the closed position. Damper blades  16  are shown pressed against damper blade stops  68 . The damper blades  16  are locked in the closed position by a thermal lock  70 . In the preferred embodiment, thermal lock  70  is fabricated from a bi-metallic strip that is attached to damper frame  18 . In low temperatures, thermal lock  70  rests flat against the wall of damper frame  18 , and damper blades  16  are free to open and close without interference from thermal lock  70 . However, in high temperature conditions the damper blades  16  will be closed by actuator  40  and press against damper blade stops  68 . As the temperature increases, thermal lock  70  bends due to the different expansion rates in metals used to form the bi-metallic strip. Once heated, the bi-metallic strip extends outward into the travel path of damper blades  16  and prevents them from moving back to the open position. 
     An advantage using thermal lock  70  is that it provides an extra measure of protection by ensuring that the damper  10  cannot open in high temperature conditions. 
     While the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in detail may be made therein without departing from the spirit, scope, and teaching of the invention. For example, the material used to fabricate the damper may be anything suitable for the intended use in conditions of potential fire, smoke, or toxic fumes. The size and shape of the damper may also vary. The number of blades may vary in size, shape or orientation. The rotating shaft  28  may be exchanged with other suitable blade drive devices. 
     Novelties: 
     1. Powered butterfly. 
     2. Round, oval or rectangular configuration. 
     3. Two direction lead screw turning that holds the damper in open, closed or intermediate positions for pressure setting when lead screw stops. No spring or other locking means needed. 
     4. Heat responsive drive to closed or opened position by thermal switch. 
     5. An easily adjustable mechanism to set power and stroke for various size dampers. 
     6. Computer drive compatible D.C. electric motor. 
     Accordingly, the invention herein disclosed is to be limited only as specified in the following claims.