Abstract:
The invention is a damper that closes off supply duct air when the unit is off to prevent air from exiting through the outlet, and opens when the unit is on to allow room air and/or supply duct air to exit through an outlet. The damper may be either motorized or mechanically biased.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional patent application No. 60/950,789 filed Jul. 19, 2007. The application also claims priority to U.S. provisional patent application No. 60/956,056 filed Aug. 15, 2007. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a damper for a positive pressure air cleaner. 
     2. Related Art 
     A positive pressure air cleaner is disclosed in U.S. Published Patent Application No. 2006/0177356. 
     SUMMARY OF THE INVENTION 
     The invention is a damper arrangement for an air cleaner. The damper closes off supply duct air when the unit is off to prevent air from exiting through the outlet, and opens when the unit is on to allow room air and/or supply duct air to exit through an outlet. The damper controls air flow from two sources, and then exhausts air to one of the two sources. In particular, the damper of the present invention is in fluid communication with both a closed loop supply duct system and ambient room air. The damper always permits some flow of air from the closed loop supply duct system to supply positive air pressure to the room, but may selectively allow or completely deny drawing air from the ambient room. After passing through the damper, the air is filtered and then exits to the ambient room. 
     The damper may be motorized, or may be mechanically biased using a spring. 
     The louvers that allow room air into the air cleaner may be adjusted from a fully open position to a fully closed position. The air louvers may be adapted to provide an air inlet cross-sectional area that is smaller than the cross-sectional area of the supply duct. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is an elevated view of a first embodiment of the air cleaner of the present invention having a first room air grill; 
         FIG. 2  is an elevated view of a second embodiment of the air cleaner of the present invention having a second room air grill; 
         FIG. 3  is an elevated view of the second embodiment of the air cleaner shown in  FIG. 2 , with a partial cutaway of the floor to illustrate a supply duct; 
         FIG. 4  is a side section view of the air cleaner of the present invention in the “off” position; and 
         FIG. 5  is a side section view of the air cleaner of the present invention in the “on” position. 
         FIG. 6  is a side section view of an air cleaner of the present invention with the motorized damper in a closed position relative to inlet room air; and 
         FIG. 7  is a side section view of the air cleaner according to  FIG. 6 , with the motorized damper in an open position relative to inlet room air. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
       FIG. 1  illustrates a perspective view of the air cleaner of the present invention. In this air cleaner, shown generally at  18 , a first grill  20  is shown, with an adjustment slide-type damper  22  that allows room air to pass through first grill  20  into air cleaner  18 . 
       FIG. 2  illustrates an alternate embodiment in which a second grill  24 , third grill  26 , and fourth grill  28  are provided. Each grill,  24 ,  26 , and  28  is provided with a second adjustment slide-type damper  30  that allows room air to pass through the grills,  24 ,  26 , and  28  into air cleaner  18 . 
       FIG. 3  shows the alternate embodiment installed over a supply duct which runs under a floor. 
       FIG. 4  shows the damper  41  in a closed position, and the air cleaner  18  “off.” The supply duct S air exits through either first grill  20 , or second, third, or fourth grills,  24 ,  26 ,  28 , such grills being generally designated R in  FIG. 4 . 
       FIG. 5  shows the damper  41  in the open position, and the air cleaner  18  “on” in which the fan is pulling air from the supply duct S and the room air inlet R. The air from the room air inlet R and the supply duct S mix and then travel to the outlet  42 . Within the exit path of outlet  42 , there is shown a series of air filters for cleaning the air as it flows through the outlet. The air cleaner  18  (which is a positive pressure air purification unit) is shown disposed such that its supply duct inlet S is in fluid communication with supply duct air from a closed loop supply duct. More particularly, the positive pressure air purification unit  18  is disposed on top of the closed loop supply duct. The closed loop supply duct S is a conventional one such as those found in homes with central air conditioning and heating where a duct system that does not obtain air from outside the house or enclosure delivers heated or cooled air via a forced air duct system. 
     The air cleaner  18 , alternately referred to as a positive pressure air purification unit  18 , also has a room air inlet which may be variably positioned between an open position and a closed position, which determines whether air may be drawn from the room into the positive pressure air purification unit  18 . When in a closed position as shown in  FIG. 6 , the room air inlet does not allow air to flow from the room into the positive pressure air purification unit. When in an open position as shown in  FIG. 7 , the room air inlet allows air to pass into the positive pressure air purification unit  18 . 
     The motorized damper  40  travels between a first position and a second position. In the first position shown in  FIG. 6 , the motorized damper  40  prevents air from entering into the positive pressure air purification unit  18  from the room air inlet R, but allows an unrestricted air path for supply duct S air to enter the positive pressure air purification unit  18  from the exterior thereof. This arrangement maximizes the opportunity for room temperature control and further maximizes the level of positive air pressure in the room. 
     In the second position shown in  FIG. 7 , the motorized damper  40  permits air to enter into the positive pressure air purification unit  18  from the room air inlet R, and also allows supply duct S air to simultaneously enter the positive pressure air purification unit  18 . It should be noted that in this second position, the damper  40  restricts but does not completely eliminate air sourced from the supply duct S. This second position of the motorized damper  40  also ensures that positive air pressure is provided in the room. 
     In both positions of the motorized damper  40 , it is understood that the air flow is drawn through the positive pressure air purification unit  18  by a fan. Accordingly, there can be no air flow without the fan in operation, unless the supply duct is itself delivering forced air through the central heating and air conditioning system. As a result, it is important to the present invention that a positive air pressure is maintained, and that the air exiting the positive pressure air purification unit  18  be purified (e.g. allergens, dust, dirt, pollen, smells, etc.). Positive pressure in a room prevents the further entry and contamination of room air by second hand smoke, allergens, dust, dirt, pollen, etc. 
     As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.