Abstract:
A damper unit is provided that is adapted to be positioned in a furnace duct line. The damper unit has a housing which is in communication with a fresh air source and a furnace system. The housing has a damper blade which is moveable between an open position which allows air flow through the housing and a closed position which prevents air flow through the housing. The blade is coupled with a solenoid so that when the solenoid is activated the blade is moved to an open position allowing air flow through the housing. Further, a fan is located in the housing adjacent the damper blade. The fan operates to move air into and out of the housing and across the damper blade when the damper blade is in its open position. In one embodiment, a pair of sealing ridges are provided on the interior of the housing. When the damper blade is in a closed position, it is in abutting relationship with the sealing ridges so that air flow across the closed damper blade is substantially prevented by the damper blade and the sealing ridges.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/036,391, filed Jan. 24, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to furnace dampers, and more specifically, to furnace dampers which can selectively provide fresh air to a furnace while the furnace is in operation, and which can be effectively sealed when the furnace is not in operation. 
     Newer technologies in home construction have resulted in homes which are more and more “air tight.” As a result, these homes are more completely closed and do not allow fresh air to flow into the structure. However, research has shown that a certain amount of fresh air flow is needed to dilute man-made household pollutants which may exist in a home, such as formaldehyde found in paints, volatile organic compounds found in sealants, and toluene found in binders. In order to combat these pollutants, efforts have been made in the area of furnace filter designs to improve the quality of indoor air. However, due to maintenance problems and certain design limitations, these furnace filters do not adequately remove harmful pollutants. 
     In general, when fresh air flow is increased, the indoor air quality is also increased. At least in part due to these concerns regarding the introduction of fresh air into modern homes, changes were made in the 1991 Uniform Mechanical Code (UMC) provisions regarding fresh air introduction for furnaces with respect to air supply. The UMC now requires that a fresh air intake of 15 cubic feet per minute (cfm) per person be supplied by an outside source. Section 706 of the UMC states: 
     Circulating air shall be taken from outside the building or from the conditioned space, or both. Heating systems regulated by this code and designed to replace required ventilation shall be arranged to discharge into the conditioned space not less than the amount of outside air specified in the Building Code. 
     A typical ventilation standard which is used by many engineers is the American Society of Heating, Refrigeration, and Air-Conditioning Engineers Standard 62-1989. This standard recommends 0.35 air changes per hour, but not less than 15 cfm per person fresh air flow. 
     Attempts have been made to meet this standard by providing a “passive” fresh air system. This passive fresh air system utilizes an air duct that connects an outside air source to the return air duct of the furnace system via a fresh air supply duct. In this passive fresh air system, fresh air is drawn into the return air duct simply from the suction generated by the main blower fan of the furnace. Thus, these passive systems have been designed to rely upon the main blower fan of the furnace to provide the required amount of suction so that a minimum of 15 cfm per person of fresh air is drawn into the return air duct of the furnace system. This passive system does not regulate the amount of fresh air actually entering the system and does not ensure that the standard of 15 cfm per person of fresh air is being met. 
     Along with the above disadvantages, the passive fresh air systems being used do not prevent fresh air from flowing into the return air duct of the furnace when the main blower fan of the furnace is not operating. Thus, unwanted outside air can enter the return air duct of the furnace system even when the main blower fan of the furnace is not in operation. Unwanted cold air increases the amount of heating the furnace must accomplish, which in turn increases the overall energy costs to the consumer. Further, the entrance of cold air into the return air duct in extremely cold environments can result in damage to pipes which may exist in and around the furnace. 
     Additional problems also exist when excess cold air enters the return air duct of the furnace system. The cold air may cause the products of combustion (principally carbon monoxide, carbon dioxide and water vapor) to condense on the inner surface of the heat exchanger. This condition creates an environment in which the combustion gasses begin to condense out and cause the formation of carbonic acid. This carbonic acid may damage the interior of the furnace through corrosion, causing a reduction in the useful life of the furnace. If a sufficient amount of corrosion takes place, a health hazard may exist if cracks form in the heat exchanger. The existence of cracks in the heat exchanger can cause the heating chamber to fracture which may allow carbon monoxide to mix with the heated air in the room, or to be exhausted improperly. As is well known, carbon monoxide poisoning can lead to illness and sometimes death. 
     Therefore, an electrically controlled damper is needed which can inject the proper volume of fresh air into the return air duct of a furnace system. Further, an electrically controlled damper is needed which will substantially prevent unwanted fresh air from entering the return air duct when the furnace is not in operation. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an electrically controlled damper which operates to inject the proper volume of fresh air into the return air duct of a furnace system when the furnace is in operation. 
     It is a further object of the invention to provide an electrically controlled damper which will substantially prevent unwanted fresh air from entering the return air duct of the furnace system when the furnace is not in operation. 
     It is another object of the invention to provide a damper which allows communication between a fresh air source and a furnace system and which can be effectively insulated from the fresh air source when the damper is in a closed position. 
     According to one aspect of the present invention, the foregoing and other objects are achieved by a damper unit adapted to be positioned in a furnace duct line. The damper unit has a housing which is in communication with a fresh air source and a furnace system. The housing has a damper blade which is moveable between an open position which allows air flow through the housing and a closed position which prevents air flow through the housing. The blade is coupled with a solenoid so that when the solenoid is activated the blade is moved to an open position allowing air flow through the housing. Further, a fan is located in the housing adjacent the damper blade. The fan operates to move air into and out of the housing and across the damper blade when the damper blade is in its open position. 
     In another aspect of the invention, a pair of sealing ridges are provided on the interior of the housing. When the damper blade is in a closed position, it is in abutting relationship with the sealing ridges so that air flow across the closed damper blade is substantially prevented by the damper blade and the sealing ridges. 
     Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings which form a part of the specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views: 
     FIG. 1 is a partially schematic perspective view of a furnace system using the motorized damper according the present invention; 
     FIG. 2 is a side elevation view taken along line  2 — 2  of FIG. 1, with parts being partially broken away to show particular features of construction; 
     FIG.  3 . is a sectional view taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a sectional view taken along line  4 — 4  of FIG. 2, with the blade shown in an open position in broken lines; 
     FIG. 5 is a partial sectional view taken along line  5 — 5  of FIG. 4, with the actuating means shown in a position such that the damper blade would be open; 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG. 4 with parts being broken away to show particular details of construction; 
     FIG. 7 is a sectional view taken along line  7 — 7  of FIG. 4, with the damper blade shown in its closed position; 
     FIG. 8 is a view similar to FIG. 7 with the damper blade shown in an open position; 
     FIG. 9 is an enlarged sectional view taken along line  9 — 9  of FIG. 6; 
     FIG. 10 is a side elevational view of an alternate embodiment of the present invention with parts being broken away to show particular details of construction; and 
     FIG. 11 is an exploded perspective view of the embodiment shown in FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in greater detail and initially to FIGS. 1,  2  and  4 , a damper in accordance with the present invention is represented broadly by the numeral  10 . Damper  10  is used to couple a return air duct  12  of a furnace system  14  with air from outside the building or structure. Damper  10  is typically coupled to return air duct  12  via duct sections  16  and  18 . Located on opposite ends of damper  10  are partially spherical end caps  20 . End caps  20  operate to couple duct sections  16  and  18  with damper  10 . 
     Referring more particularly to FIGS. 2 through 4, damper  10  includes an outer housing  22  to which end caps  20  are attached. Preferably, in this embodiment, housing  22  is cylindrically shaped. Located within housing  22 , and attached thereto is a fan  24  sized to deliver a desired amount of fresh air into furnace system  14 . Fan  24  is used to move air through damper  10 , as is more fully described below. Fan  24  is equipped with a motor  26  which is operably connected to an electrical supply  28  and a controller (not shown). Attached to a shaft  30  of motor  26  is a fan blade  32 . Fan blade  32  is shown in FIG. 3 having four fins  34 , although more or less fins could be used. Fan  24  is held within housing  22  via mounting arms  36  and angle brackets  38 . Mounting arms  36  are fixed to motor  26 , such as by screws  40 . Mounting arms  36  are coupled to angle brackets  38  with bolts  32  and angle brackets  38  are coupled to housing  22  with bolts  42 . This method of attachment of fan  24  allows motor  26  to be replaced should it malfunction. 
     In operation, fan  24  cooperates with a damper blade  44  which is pivotally mounted to housing  22 . Damper blade  44  has an upper section  46  and a lower section  48  which are each in the shape of a truncated cone. Upper section  46  and lower section  48  are oriented relative to each other so that the diameter existing where upper section  46  and lower section  48  meet is slightly greater than the diameter existing at a top surface  50  of upper section  46  and a bottom surface  52  of lower section  48 . Upper section  46  and lower section  48  form a hollow interior which may contain an insulating material (not shown). Alternatively, damper blade  44  can be made from a solid block of plastic material. Extending through damper blade  44  is a cylindrical pivot pin  54 . Pivot pin  54  extends through a pair of opposing through holes  56  in housing  22 . Through holes  56  may be fitted with bearings or bushings, which are not shown. A first end  58  of pivot pin  54  is held in place with a nut  60  and washer  62 . Disposed in the interior of housing  22  along pivot pin  54  and on opposing ends of damper blade  44  are a pair of washers  64 . The end of pivot pin  54  opposite first end  58  is threaded into a crank shaft  66  located exteriorly of housing  22 . The crank shaft  66  is rigidly secured to a circular crank  68  as best seen in FIGS. 4,  5  and  6 , and which is more fully described below. 
     Crank  68  has extending therefrom a linking pin  70  which is rigidly secured to crank  68 . Linking pin  70  is used to secure a connecting rod  72  to crank  68 . Connecting rod  72  has a first end  74  which is pivotally connected through linking pin  70  to crank  68 . Connecting rod  72  has a second end  76  which is pivotally connected to a coupling  78  on a solenoid shaft  80  of a solenoid  82 . Solenoid  82 , connecting rod  72  and crank  68  are used to impart a pivoting motion on damper blade  44 . Solenoid  82  is held in place relative to housing  22  with a holding bracket  84  and a spacer bracket  86  as best seen in FIG.  4 . Holding bracket  84  may be secured to spacer bracket  86  via rivet  88  and spacer bracket  86  may be held in place on housing  22  with any suitable attachment means such as by an adhesive or welding. Solenoid  82  is connected to an electrical supply and a controller (not shown) via wires  90 . 
     Located adjacent linking pin  70  on crank  68  is an eyelet  92 . Eyelet  92  is rigidly secured to crank  68 , such as by welding. Extending between eyelet  92  and a support  94  is an extension spring  96  as best seen in FIGS. 2,  4  and  5 . Extension spring  96  operates to bias damper blade  44  to a closed position. A protective cover  97  is secured to housing  22  and over solenoid  82 , connecting rod  72  and crank  68 . Cover  97  is secured to housing  22  with screws  99 , although other attaching means could be used. 
     As shown in FIG. 4, damper blade  44  is in its closed position. In this position solenoid  82  is not energized. Thus crank  68 , extension spring  96  and connecting rod  72  are in position as shown in FIGS. 2 and 4. When it is desired to open damper blade  44 , solenoid  82  is energized and crank  68 , connecting rod  72  and extension spring  96  will assume the position shown in FIG.  5 . When solenoid  82  is energized, a rotating motion is imparted upon pivot pin  54 . Damper blade  44  is secured to pivot pin  54  through a connecting bolt  98  so that damper blade  44  rotates with pivot pin  54 . Thus, with solenoid  82  energized, damper blade  44  will assume a position as best seen in FIG.  8 . In this position, air is permitted to flow through housing  22 . 
     When solenoid  82  is de-energized, damper blade  44  will return to a closed position caused by extension spring  96 , as best seen in FIG.  7 . In the closed position, damper blade  44  is in abutting relationship with a pair of sealing ridges  100 . Ridges  100  are constructed from a rigid seal support  102  and a sealing material  104 . Material  104  may be secured to support  102  through any suitable attaching means, such as by an adhesive. As best seen in FIG. 6, sealing ridges  100  are generally semi-circular in shape, but do not extend to a full semi-circle. This is necessary to allow damper blade  44  to pivot to its open position as best seen in FIGS. 7 and 8. The outer-most diameter of damper blade  44  is sized to allow clearance between the outer diameter and housing  22  as best seen in FIG.  9 . 
     In use, as best seen in FIG. 1, damper  10  is placed in furnace system  14  intermediate return air duct  12  and the exterior of the structure. Duct section  16  extends from damper  10  through a roof  106 , and has a protective end cap  108  thereon. Furnace system  14  is provided with a furnace  110  to which is coupled an air supply source  112 , a gas supply source  114  and return air duct  12 . Air supply  112  and return air duct  12  supply furnace  110  with the necessary combustion air and gas supply source  114  supplies furnace  110  with combustion gasses. Furnace  110  is also equipped with a vent  116  which extends beyond roof  106 . 
     In use, damper  10  is coupled to a controller so that damper  10  will supply fresh air to return air duct  12  when furnace  110  is in operation. More specifically, when the main blower fan of furnace  110  is in operation, a signal is sent to solenoid  82  which activates solenoid  82  and retracts solenoid shaft  80 . This retraction of solenoid shaft  80  operates through connecting rod  72  to rotate crank  68 . The rotation of crank  68  effects a pivoting motion on pivot pin  54  and therefore a pivoting motion on damper blade  44 . The damper blade in its open position can best be seen in FIG.  8 . In this open position, air is allowed to pass through housing  22  and into return air duct  12 . Further, when solenoid  82  is energized a signal is simultaneously sent to fan  24  to activate the fan and turn fan blade  32 . Thus, not only will damper blade  44  be in an open position, but fan  24  will be operating to pull air from the exterior of the structure into return air duct  12 . When the main blower fan of the furnace ceases to operate, solenoid  82  is de-energized, as is fan  24 . Spring  96  will then return damper blade  44  to a closed position. Damper blade  44  cooperates with sealing ridges  100  to prevent air flow through housing  22 . Thus, damper  10  operates to inject a desired volume of fresh air to the return air duct of a furnace system when the main blower fan of the furnace is in operation. Further, damper  10  will prevent unwanted fresh air from entering the return air duct of the furnace system when the furnace is not in operation. 
     An alternative embodiment of damper  10  is shown in FIGS. 10 and 11. In this embodiment endcaps  20  are again used on either side of a housing  22 . In this embodiment, housing  22  defines a portion which is only surrounded on three sides, as can best be seen in FIG.  11 . Further, in this embodiment housing  22  is generally rectangularly shaped. In this embodiment, fan  24 , and more particularly motor  26 , is held within housing  22  near an upper end thereof with mounting arms  118 . Mounting arms  118  are secured to housing  22  such as by welding or bolts. Disposed interiorly of housing  22  below fan  24  is a lip  120  which extends completely about the interior perimeter of housing  22 . Lip  120  defines a central opening  122  which is slightly smaller than the diameter of fan blade  32 . Lip  120  has a lower surface  124  on which is secured a sealing gasket  126 . Disposed immediately below gasket  126  is a damper blade  128 . 
     Damper blade  128  is generally rectangular and operates to completely seal opening  122  when damper blade  128  is in abutting relationship with sealing gasket  126 . Damper blade  128  is fixedly secured to a lever arm  130  which is in turn hingedly connected to housing  22  at a pivot point  132 . Lever arm  130  is pivotally connected to a connecting link  134  which is in turn pivotally connected to a solenoid  136 . Solenoid  136  is secured to housing  22  via a holding bracket  138  and a spacer bracket  140 . A cowling  142  is placed on housing  22  to cover solenoid  136 , connecting link  134  and lever arm  130 . Cowling  142  defines an interior space  144  which allows damper blade  128  to pivot to an entirely open position as best seen in broken lines in FIG.  10 . Further, damper blade  128  may have secured thereto a layer of insulation  146 . Cowling  142  may be sized so as to allow blade  128  with insulation  146  thereon to pivot to a completely open position. When damper blade  128  is pivoted to its completely open position, damper blade  128  is completely away from the opening  122  formed in lip  120 . In this manner, damper blade  128  can be pivoted so as to not interfere with the overall cross-sectional area of housing  22 . In this embodiment, fan  24  is located on the exterior side of damper blade  128  so that when fan  24  is activated and damper blade  128  is pivoted to its open position, air will be pushed through opening  122  and across damper blade  128 . The invention as shown in this embodiment is used as described above for the previous embodiment of damper  10 . 
     Therefore, the invention provides a damper which can meet the current requirements of the Uniform Mechanical Code for providing fresh air to a furnace system. Further, the damper of the present invention provides an electrically controlled damper which is designed to seal off and insulate a fresh air intake duct from the outside environment when the furnace is not in operation. 
     From the foregoing, it will be seen that this invention is one well-suited to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.