Abstract:
A one-way soffit vent has an upstream valve seat and a downstream vented cover having a boss extending in the upstream direction. A valve disk is reciprocally mounted on the boss and biased against the valve seat.

Description:
BACKGROUND 
     This invention relates to a soffit vent. 
     Bathrooms, kitchens, and other enclosures in homes and other buildings often have exhaust fans to actively vent these enclosures. Ductwork typically extends between the fan and the outside of the building. One place for the outlet of the ducting which, as compared with a wall or the roof of a building, may minimize the cost of installation, is the soffits. Air blown by the fan should, of course, exit the home; however, it is desirable to avoid back drafts, especially in cold weather. It is also desirable to block the migration of vermin or insects into the home through the ducting. In an effort to achieve these goals, U.S. Pat. No. 6,149,516 to Mantyla discloses a soffit vent at the outlet of the ducting which has a weighted flapper valve that will close when the fan is off. 
     This invention seeks to provide an improved soffit vent. 
     SUMMARY OF INVENTION 
     A one-way soffit vent has an upstream valve seat and a downstream vented cover having a boss extending in the upstream direction. A valve disk is reciprocally mounted on the boss and biased against the valve seat. 
     Other features and advantages of the invention will become apparent from the following description in conjunction with the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In the figures which illustrate example embodiments of the invention, 
         FIG. 1  is a side schematic view of a vented enclosure of a building using a soffit vent according to this invention, 
         FIG. 2  is a top perspective view of a soffit vent according to this invention, 
         FIG. 3  is a bottom perspective view of the soffit vent of  FIG. 2 , 
         FIG. 4  is an exploded view of the soffit vent of  FIG. 2 , 
         FIG. 5  is a cross-sectional view of the soffit vent of  FIG. 2  showing the vent closed, and 
         FIG. 6  is a cross-sectional view of the soffit vent of  FIG. 2  showing the vent open. 
     
    
    
     DETAILED DESCRIPTION 
     Turning to  FIG. 1 , a building  10  has an enclosed room  12  with an exhaust fan  14  in the ceiling. The outlet of the exhaust fan is connected to one end of a duct  16 ; the other end of the duct is connected, by hose clamp  18 , to the upstream end of soffit vent  20 . As seen in  FIG. 1 , the soffit vent is mounted through the soffit  22  of the building. 
     Soffit vent  20  is detailed in  FIGS. 2 to 4 . Turning to these figures, the vent may have, in downstream order, a first sleeve section  30 , a second sleeve section  32  which is connected to a valve seat  40 , and a cover  42 . A valve disk  44  and a coil spring  46  may extend within the second sleeve section  32  upstream of the cover  42 . 
     The first sleeve section  30  may have an upstream smaller diameter cylindrical stub  52  terminating at a step runner  53  to a larger diameter concentric downstream cylindrical stub  54 . Each cylindrical stub  52 ,  54  may have a pair of outwardly projecting tabs  56 . The first sleeve section  30  may step outwardly again to a cylindrical base  58  with a pair of mounting notches  60 . 
     The second sleeve section  32  may have a smaller diameter upstream cylindrical stub  64  terminating at a step runner  63  to a larger diameter downstream cylindrical stub  66 . The upstream stub  64  may have a pair of mounting tabs  68 . The valve seat  40  may be connected to the smaller diameter upstream cylindrical stub  64  of the second sleeve section by a web  70  which comprises four radially projecting arms. The valve seat may be a dome-shaped shell with the top of the dome-shape extending in the upstream direction. An annular cylindrical finger  72  ( FIG. 5 ) may depend from the valve seat  40  and project downstream to a blind end with a central threaded opening. 
     Valve disk  44  may have an annular portion  45  and a central web  76  which connects the annular portion to a central spring backstop  77  and an annular mounting cylinder  78 . The valve disk  44  may have a peripheral wall  80 . The radial distance to inner surface  94  of the cylindrical stub  64  of the second sleeve section  32  is chosen to be slightly greater than the radius of the valve disk  44  defined by the outer surface of peripheral wall  80 . 
     Valve cover  42  may have vent openings  82  and a central annular boss  84  which extends in the upstream direction and is internally divided by a radial wall  86  ( FIG. 5 ) with a central opening. The cover  42  may have number of fastener receiving openings  88  proximate its periphery. 
     To assemble vent  20 , mounting tabs  68  of the second sleeve section  32  may be snapped into the mounting holes  60  of the first sleeve section  30  to form a completed outer sleeve  90 . Spring  46  may be dropped over boss  84  and the annular mounting cylinder  78  of valve disk  44  may be slid over the boss  84  such that an end of the spring  46  abuts spring backstop  77 . Next, the outer sleeve  90  may be oriented so that the annular finger  72  of the valve seat is received by the opening in the boss  84  of cover  42 . A screw  96  may then be inserted through the opening in radial wall  86  of the boss and threaded to the threaded opening of the blind end of the finger  72  of valve seat  40  to hold the assembly together. 
     The result is detailed in  FIG. 5 . Spring  46  urges valve disk  44  in an upstream direction to seat against valve seat  40 . Specifically, the annular portion  45  of the valve disk may abut the downstream edge of the lip  92  of the dome-shaped shell of the valve seat  40 . When in this seated position, around the entire periphery of the valve disk, the outer surface of the wall  80  of the valve disk faces the inner surface  94  of the cylindrical stub  64  of the second sleeve section  32  at a small stand-off. Thus, the valve disk, when seated against the valve seat  40  effectively seals off the opening through the vent  20 . 
     Referencing  FIG. 1  along with  FIGS. 2 to 4 , the outer sleeve  90  of soffit vent  20  may be inserted through a soffit  22  of a building  10  and fasteners  97  ( FIG. 4 ) screwed into the soffit wall through fastener receiving openings  88  in order to secure the vent cover  42  to the soffit. A smaller diameter duct  16  (e.g., a 4″ diameter duct) may fit snugly around the smaller diameter cylindrical stub  52 . A hose clamp  18  may then be fitted around the end of the duct between the step runner  53  and the tabs  56  of stub  52  and tightened to clamp the end of the duct to the soffit vent. If, instead, a larger (e.g., 5″) diameter duct were to be used, then the smaller diameter cylindrical stub  52  could be removed and the duct clamped to the larger diameter stub  54 . The step runner  53  may be provided with a line of weakness  55  to facilitate removal of stub  52 . Further, if an even larger diameter duct (e.g., a 6″ diameter duct) were to be used, then the entire first sleeve section  30  could be demounted from the second sleeve section  32  and the duct clamped to cylindrical stub  64  of the second sleeve section with a hose clamp extending between runner  63  and mounting tabs  68 . In this instance, the second sleeve section itself acts as the outer sleeve. 
     After installation, when the fan  14  is not running, the valve disk  44  will be seated against the valve seat  40 , such that the valve defined by the various parts is closed. Any back draft will then simply serve to more firmly seat the valve disk against the valve seat, thus keeping outdoor air out. On the other hand, when the fan  14  is turned on, as seen in  FIG. 6 , air moves in a downstream direction, D, and the pressure of the exhausting air will push on the valve disk and overcome the biasing force of spring  46  to cause the valve disk  44  to unseat from the valve seat  40 . Air then exhausts through the vent. The valve cover  42  and valve disk  44  present two separate barriers against bugs and vermin entering the ducting system. 
     In a cold climate, moisture in inside air may condense out as the air is exhausted. This may cause ice build-up on surfaces of vent  20  and, in particular, on inner surface  98  of larger diameter downstream cylindrical stub  66  of sleeve section  32 . The outward step to this stub  66  provides a clearance between wall  80  of valve disk  44  and inner surface  98 . Section  32  may be designed so that this clearance is sufficient to ensure any such ice build-up does not interfere with the movement of the valve disk  44 . 
     Many modifications will be apparent to those skilled in the art. For example, the first sleeve section  30  could have only a single cylindrical stub for mounting to a duct, or it could have more than two different diameter stubs. The two sleeve sections could instead be molded as one continuous outer sleeve, or these sections could be joined in some convenient fashion other than the tab and notch configuration described. The valve seat  44  need not have a dome-shaped shell, however the dome-shape has the advantage of reducing the turbulence of exhausting air over many other shapes that could be contemplated. (Air turbulence varies the pressure on the valve disk which could result in the valve disk rattling on the valve seat.) Indeed, at least for warmer climates, the runner  63  of the step in the second cylindrical section could function as the valve seat and the valve disk could be a solid disk, rather than an annulus, which seated against this step runner  63 . The biasing coil spring  46  could be replaced by a series of coil springs, or by one or more springs of a different type, acting between the vent cover and the valve disk. 
     Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims.