Abstract:
An adaptor for a passive roof vent is presented having a base securable to a roof deck and an integrally moulded stepped collar extending from the base on one side for connecting to different air duct sizes which defines a discharge end for an air flow passageway. A central well is defined by the collar adjacent to and below the base and is open towards the other side of the base and has a hinge pin for at least one flapper valve retained in the well below the base. At least one flapper valve, hinged to the hinge pin, pivots about a closed position to which the flapper valve is biased by gravity and an open position in which the flapper valve is opened by air pressure from below within the air flow passageway. The flapper valve remains partially within the well when the flapper valve is open.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally the field of roof vents, and more particularly to the type of roof vents that may be used to provide ventilation from a building enclosure. Most particularly this invention relates to the type of roof vents that may require a flapper valve, such as is common with forced air venting from, for example, bathroom fans, range fans and the like. 
       BACKGROUND OF THE INVENTION 
       [0002]    Exhaust fans are often provided to suck moist air from bathrooms, smoke and steam from kitchens, and for other reasons. They are particularly useful in removing moist air from bathrooms where for example showering may take place which can create a great deal of steam. The removal of such moist air will limit the formation of mould or the like which can be a cleanliness and safety issue. Usually such bathroom fans are activated by a separate switch and can be turned on or off at will. Alternatively they may be automatically operated when there is enough moisture in the air or the bathroom is otherwise occupied. When activated the fan will suck air from the bathroom, usually at a ceiling level and then exhaust it to the outside through a dedicated exhaust duct. The fan creates a positive air flow that pushes the air out through the duct and then typically through a flapper valve, before it reaches the outside. The flapper valve typically opens by reason of the positive air pressure and then closes due to gravity. 
         [0003]    Various types of vent structure exist to house the flapper valve at the discharge end of the duct. In general such vent structures typically include a body on the outside which covers the duct opening and prevents weather from entering backwardly through the duct. As well, typically the vent body includes a form of grill or the like to let air pass out while at the same time to keep out pests such as birds, bugs and rodents or the like from entering the building through the duct. As well, as noted above, they typically include a flapper valve to prevent the loss of air (and thus energy) out of the discharge end of the duct when the fan is not operating. Lastly they typically include some form of collar to anchor the duct in place to the body of the vent. 
         [0004]    Although many prior designs of specialized vent bodies have been proposed in the past, in some cases roofers will cover the duct discharge end with a conventional passive roof vent. While this provides some protection for the discharge end of the duct it is generally not sufficient, in that there may be no provision of a flapper valve. Without a flapper valve this can lead to drafts in the bathroom and a loss of energy. The flapper doesn&#39;t allow the moist air to freeze. In a prior patent to Ward (U.S. Pat. No. 8,205,401), an attempt is made to provide a flapper adaptor so that a conventional passive roof vent can be adapted to perform as an end cover for a bathroom or forced air duct. In Ward there is provided a device which includes a separate flapper adaptor unit which defines a discharge chimney that extends up above the roof surface. A flapper valve hinged at an angle and attached at one end is provided on the top of the chimney. The flapper adaptor is provided with upwardly reaching fingers to allow it to be placed inside of the vent opening of the vent body and the grab the top edge of the same to keep it in place. Below a separate collar adaptor, with various collar diameters for attaching to different sizes of ducts, is provided. The separate collar adaptor, the flapper adaptor and the body of the vent are then combined together to form a complete unit. 
         [0005]    While providing a flapper valve option for the specific roof vent design shown there are certain problems associated with this prior design. The design involves three separate components each of which must be positioned correctly to ensure the combination functions as required. The use of separate components leads to the risks of installer error and leaks. As well the flapper adaptor includes a raised collar which has an angled top on which the flapper valve sits. To ensure proper functioning of the flapper valve the valve must be oriented correctly, relative to the roof incline, to prevent the flapper valve from being too hard to lift. As well the flapper valve stands proud of the roof deck meaning that the body of the vent must be large enough to accommodate the range of travel of the flapper valve when it opens and closes and the adaptor fingers will only latch onto a vent having a vent opening as shown in the drawings. Thus this prior adaptor combination is limited to being used with a roof vent the same as or substantially the same as what is shown. 
         [0006]    Other types of flapper valves provided in the prior art include: 
         [0007]    U.S. Pat. No. 4,144,802; 
         [0008]    U.S. Pat. No. 4,432,273; 
         [0009]    U.S. Pat. No. 4,593,504; 
         [0010]    U.S. Pat. No. 5,662,522; 
         [0011]    U.S. Pat. No. 5,749,780; 
         [0012]    Canadian Patent No. 2,696,466. 
         [0013]    What is desired is a simple and reliable universal adaptor that can be used in association with many different types and styles of roof vent bodies. A universal adaptor is desirable as opposed to one which can only be used in association with one specific roof vent body as taught in the prior art. Preferably such a universal device would be simple to minimize the risk of incorrect installation and in-expensive to make and use. Preferably such a product can be installed from either side of the roof sheathing. Such a design is also preferably reliable. Most preferable such a device would be made from a durable molded plastic and would be compatible with a wide range of vent bodies. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention is directed to a form of universal adaptor which may be used in association with many different vent body designs. Essentially the present invention may provide a reliable flapper valve element that can be mounted to the discharge end of an adaptive collar to connect to a forced air duct such as one coming from a bathroom fan. The present invention may present a low profile design, by mounting the flapper valve within the well formed by the adaptive collar. Preferably the design includes control over the extent of rotation of the flapper valve, through for example the use of limit stops. It may only require a low activation pressure for opening and closing the valve as compared to some of the prior art. In this way the present invention provides for an easy to use adaptor to mount on the end of a forced air discharge duct which is also efficient at permitting the desired discharge of exhaust air. The present invention may be molded from highly durable plastic and is easily retrofit to an existing installation and can be used with a wide variety of convention roof vent styles and forms. 
         [0015]    According to one embodiment the present invention provides a flapper valve adaptor for a passive roof vent, the flapper valve adaptor comprising: 
         [0016]    a base securable to a sloped roof deck and having an integrally moulded stepped collar extending from the base on one side for connecting to different air duct sizes and to define a discharge end for an air flow passageway, 
         [0017]    a central well defined by the collar adjacent to and below the base and being open towards the other side of the base from said one side; 
         [0018]    a hinge pin retained in the open central well below said base to define a central pivot axis within said central well and oriented to be generally aligned with said roof deck slope when base is secured to said sloped roof deck; 
         [0019]    a pair of opposed flapper valves hinged to said hinge pin and pivoting about a closed position in which the flapper valves is biased by gravity to close the air flow passageway and an open position in which the flapper valves are opened by air pressure from within said air flow passageway; 
         [0020]    wherein said flapper valves, remain partially within said well when said flapper valves are fully open. 
         [0021]    According to another aspect the present invention provides a method of installing a flapper valve assembly together with a passive exterior roof vent in a roof at a location having a generally planar surface which slopes down from a roof peak, said method comprising the steps of: 
         [0022]    trimming a stepped collar having an integral base to match the diameter of an air duct to be vented; 
         [0023]    securing the stepped collar to the air duct at one end and to a roof deck at the other end at said integral base; 
         [0024]    securing a hinge pin in a central well of said stepped collar in an orientation that is generally perpendicular to a roof peak and generally below the planar roof surface; 
         [0025]    pivotally securing flapper elements to said hinge pin; and 
         [0026]    mounting said exterior roof vent over said flapper valve adaptor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Reference will now be made by way of example only to preferred embodiments of the invention by reference to the following drawing in which: 
           [0028]      FIG. 1  is an exploded view of the components of an adaptor collar assembly according to one embodiment of the present invention; 
           [0029]      FIG. 2  is a side view of the components of  FIG. 1  assembled together; and 
           [0030]      FIG. 3  is a cross-sectional end view of the components of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]      FIG. 1  shows an adaptor collar according to the present invention. As shown the adaptor collar has an attachment base  10  from which extend number of different sized collars  12 ,  14 , and  16 . Each collar section is comprised of a duct attachment portion  18 ,  20  and  22  separated by horizontal steps  24  and  26 . The smallest diameter connector  12  is the furthest from the base  10  and each successive connector section  14 ,  16  is of a larger diameter. Three sizes are believed to cover the usual range of ducts that might be used in typical duct work in a building. It will be understood that the collar sections that are too small to match the air duct which attaches to the adaptor may be trimmed off before the air duct connection is made. 
         [0032]    It will also be understood that the duct collar sections  12 ,  14 , and  16  are integrally moulded to each other and the last or largest one  16  is integrally moulded to the base  10 . In this way once the duct is attached to the appropriate sized collar  12 ,  14  or  16 , the adaptor collar forms a direct airway connection to the outside. The base  10  can be mounted on the inside or outside of a building enclosure such as by being incorporated into a shingle roof for example, with the collar extending downwardly through an opening in the roof and down towards a connecting air duct so that a connection can be made. 
         [0033]    As shown each collar consists of a generally vertical sidewall section  18 ,  20  and  22  separated by generally horizontal sections or steps  24  and  26 . The generally vertical sidewall sections  18 ,  20  and  22  may be tapered to make it easier to secure the duct over the collar sections. In this case the taper may extend from a narrower diameter further from the base  10  to a larger diameter closer to the base  10 . The horizontal sections simply transition the collar diameter from one size to the next. The steps  24 ,  26  could be placed at an angle, rather than being at 90 degrees to the collar section, but the 90 degree configuration works well and is convenient to mould and so is the most preferred. 
         [0034]    The largest collar section  16  is located just below the base  10 . It will be understood that in all cases this collar section will be in use once the duct is attached, as it is the largest size collar. If the duct is to attach to a smaller sized collar then the duct is attached before the largest collar section. If the duct attaches to the middle collar section then the smallest collar section will be trimmed off and the only the middle and largest collar section will remain. Finally if the duct attaches to the largest collar section the first two sections are trimmed off and only the largest collar section remains. As explained in more detail below, the collar sections  14  and  12  are removed, but the section  18  and step  24  are kept. 
         [0035]    As shown in  FIG. 1  the largest collar section forms a well  30  below the base although the well may be any shape in plan view, a circular well is preferred as most air ducts are also circular. Thus, the circular well provides an outer surface which can be easily fit and made air tight with a connecting circular air duct. 
         [0036]      FIG. 1  shows a flapper valve hinge pin assembly  32 . It consists of a retaining ring  34 , a hinge pin  36  extending across the diameter of the retaining ring  34 . Preferably the retaining ring  34  and hinge pin  36  are formed from moulded plastic which has some resiliency. The retaining ring  34  may have an external diameter which matches the internal diameter of the well  30  just above the step  24 . In this way the retaining ring  34  may be fit inside of the well  30 . Detents  35  (see  FIG. 2 ) may be used to secure the retaining ring  34  within the well  30 . Thus, in one embodiment the retaining ring  34  may be pushed down into the well by an installer and snap fit over the detents to be physically retained in the well  30 . The present invention comprehends various ways of securing the retaining ring  34  within the well including fasteners, adhesives, plastic welding and even a simple frictional or interference fit and the like, but it is believed that the preferred form of securing the retaining ring in the well is through a deflection over the detents as described above. As well, although good results have been achieved with the retaining ring as described the present invention comprehends various ways that the hinge pin  36  may be secured within the well. For example the hinge pin  36  could be made a simple straight member that fits into slots in the side walls of the collar for example. All that is required is a hinge pin  36  that can be aligned with the roof slope (namely, generally perpendicular to the roof peak and sloped parallel to the plane of the roof slope) to permit the smooth functioning of the flapper valves as described below. 
         [0037]    Also shown are two flapper valves  50  and  52 . Each of the flapper valves includes a pair of snap connectors for securing the flapper valves to the hinge pin. Each of the flapper valves has a generally semicircular shape and the snap connectors  54  of one are offset relative to the snap connectors  56  of the other. In this way they can be attached to the hinge pin from opposite sides to form a circular flapper valve which covers the airflow passageway through the well  30 . It can now be appreciated that the step  24  acts as a valve seat for the outer edges of the flapper valves  50 ,  52 . In this way the flapper valves close off the air passageway through the well  30  around the full circumference of the central well  30 . 
         [0038]    The snap connectors  54 ,  56  are sized and shaped to retain the flapper valves onto the hinge pin, but are loose enough so that the flapper valves can freely pivot about the hinge pin  36 . In this way the present invention provides a split flapper valve in which each half is smaller in weight than one which needs to cover the whole opening and thus easier to lift off the valve seat or step  24  than a full circular flapper valve as shown in the prior art. As well the preferred form of the flapper valves is a moulded plastic part which then rotates on and off of the valve seat according to the air pressure from below. The use of light weight plastic parts reduces if not substantially eliminates the noise that can be associated with other types of valves which constantly open and close and make a noise each time. 
         [0039]    As can be seen in  FIG. 2  the valves when fully open only project a small amount H above the base  10  of the vent. In this way the adaptor assembly of the present invention will fit below all manner of exterior roof vent styles and designs. In terms of sizes, the steps  18 ,  20  and  22  may be each made 1.5 inches long. Further, the diameter of the bottom of step  22  may be 3.9 inches, the next step 4.9 inches and the last step 5.9 inches, with a 1° vertical taper. A duct  40  is shown in dotted outline connecting to the smallest duct connector  12  by way of example. 
         [0040]      FIG. 3  is a cross-section along lines  3 - 3  of  FIG. 2  of the present invention. As shown, rotation stops  70  may be formed into the snap fittings  54 ,  56  to limit the over rotation of the flapper valves. This has two desired effects including preventing the valves from getting to upright in which case they may have a tendency not to properly close and to prevent the tops of the valves from protruding very far above the surface of the base making the present design a low profile design which is compatible with many vent body styles which may be used to cover the flapper valve adaptor. While any range of angles can be used, reasonable results have been obtained by limiting the range of motion to less than about 60° and most preferably to about 45°. 
         [0041]    The installation of the present invention can now be understood. The first step is to locate the ducting to be vented and to form a hole in the roof deck at an appropriate location. Then the adaptor collar can be sized to the ducting by removing any collar sections that are too small. The removal can be done with a knife, scissors, sheers, snips or the like as the plastic material while durable can be fairly easily cut. An area of thinner plastic can be molded into the adaptor to facilitate such trimming. The next step is to attach the duct to the appropriate collar using convention methods which might include glue, adhesive, a duct clamp and the like. Once the duct is secure the duct can be fed back down through the hole and the base  10  secured to the roof in the normal manner. As shown in  FIG. 1 , markings  80  can be provided to assist the installer in lining up the base. The base may be provided with visual markings to help the installer orient the base correctly, such as having an Up arrow formed into the plastic or added by way of a label on both sides of said base  10  so it can be correctly installed either above or below the roof deck as the installer wishes. In the case of an outside installation, the next step is the interleaving of the base  10  into a layers shingle covering in the usual manner to ensure that the base is part of a waterproof roof surface covering the underlying roof deck. 
         [0042]    The next step is to insert and align the hinge pin. Typically a roof surface will have a certain incline or slope. There is also typically a roof peak, and a generally planar roof surface which slopes down and away from the roof peak towards the eaves. In this way water is encouraged by gravity to drain off the roof, into the eaves and then through downspouts onto the ground. What is desired is to orient the hinge pin so that it follows the slope or fall line. This is desired to keep the flapper valves balanced and to prevent the flapper valves from being oriented in a way that would require more effort to raise one flapper valve  50  as compared to the other one  52 , for example when the air pressure in the duct below the vent is raised by means of a bathroom exhaust fan or the like. By aligning the hinge pin at generally at about  90 ° to the roof peak, and parallel to the slope of the planar roof surface the activation pressure required for each flapper valve will be generally evenly balanced. The flapper valves  50 ,  52  can be tested by turning on the fan, such as a bathroom fan or range fan, to make sure the air pressure is enough to open the flapper valves  50 ,  52  to the desired angle. The limit stops effectiveness can also be evaluated. Then, the next step is to place a conventional exterior roof vent overtop of the base to complete the installation. As noted above the low profile H of the adaptor of the present invention makes it suitable for many different forms of exterior roof vent. 
         [0043]    It can now be appreciated that the present invention provides a simple and easy to use adaptor which can be placed into the air flow passageway of an air duct exhaust system to add a flapper valve closure to the air flow passageway. The present invention may be used with many different styles and types of exterior roof vent and is inexpensive and easy to install. Rather than requiring a dedicated type of exterior roof vent body for the flapper valve, the present invention can be used with any conventional mass market style of exterior roof vent, that provides a modest amount of head space below the raised cover. Further, by orienting the hinge pin axis generally perpendicular to the roof slope, the valve configuration permits the use of two smaller half valves, which will have substantially identical activation air pressures, and such activation air pressures will be substantially the same across the normal range of conventional roof slopes. In contrast the eccentric mounting of the hinge axes of the prior art can result in larger changes in activation pressure across the range of roof typical roof slopes. 
         [0044]    It will be understood by those skilled in the art that various modifications and alterations can be made without departing from the broad scope of the appended claims. Some of them have been discussed above and other will be apparent to those skilled in the art. For example although a hinge pin support ring is shown, the hinge pin could be supported in a number of other ways. All that is required is the ability to orient the hinge pin to the slope to even out the resistance to air pressure provided by both halves of the split flapper valve.