Patent Application
20090031649
1. Field of the Invention
This invention relates to fenestration products composed primarily of plastic.
2. Background Art
Plastic is used in a variety of fenestration products such as skylights and windows in buildings as an alternative to a glass panel. Plastic and glass fenestration panels each have their respective advantages and disadvantages. Glass is relatively inexpensive, has good optical properties, is scratch resistant and stable in a variety of harsh environments. Glass, however, is relatively heavy, susceptible to catastrophic failure and can be difficult to handle and fabricate. There is a wide a variety of plastics available for use in fenestration products. Some are low cost, tough, readily formable and environmentally stable. Many plastics, however, are susceptible to scratching, lose their physical properties with age or exposure to environmental factors, and can be relatively expensive.
The use of plastic and fenestration products, although a very small portion of the market compared to glass, is still quite significant. Plastic panels are used in doors for example, particularly storm doors to minimize the risk of injury due to glass fracture. Acrylic dome panels are used in both residential and industrial building skylights, as illustrated in U.S. Pat. Nos. 3,434,257; 4,514,944, and 4,344,261. Recently, the plastic dome skylight has been introduced having acrylic dome mounted in a polyurethane frame molded in situ about the dome peripheral edge, as illustrated in published U.S. patent application 2005/0178078, illustrated in website, www.vtechindustries.com/products.html and available from Vtech Industries, Inc. and Carlisle SynTec, Inc.
The focus of the development efforts in the plastic fenestration product area has been, how to mount the plastic panel to the building opening in a secure leak proof manner, while securely supporting the plastic panel on a frame or curb in a structural manner. Many of the mounting systems are comprised of multiple component parts which require assembly and have joints which are susceptible to water leaks. Some skylights are deck mounted, others use raised curbs. The molded polyurethane frame of the VTech™ skylight is a simple one piece molded structure which is securely bonded to the plastic dome in a leak proof manner resulting in a very high performance skylight. This skylight, however, is expensive to manufacture as the tooling and production equipment needed is costly and the raw material cost of the high performance polyurethane utilized prevents this construction system from being used in low price point skylight applications.
Accordingly, one of the benefits of the present invention is to develop a low cost fenestration product which is suitable for use in skylights or the like which can match the state of the art water intrusion standards set by the in situ molded polyurethane frame systems. It is a further advantage of the invention to develop a fenestration product which is relatively inexpensive to manufacture and requires minimal investment in capital equipment.
The fenestration product made in accordance with an embodiment of the present invention includes two main components; a frame and a plastic dome formed of a transparent material which is mounted to the frame. The dome has a central region which transmits visible light and a downwardly extending peripheral edge which extends about the peripheral wall of the frame. The dome is further provided with an outwardly extending flashing flange for mounting the assembly to a wall of a building structure surrounding a building opening.
In one embodiment of the invention, the frame comprises the unitary plastic ring having a central opening formed therein. The frame peripheral wall is preferably formed of an inverted “U” shape cross-section having an outer peripheral wall cooperating with the plastic dome and an inner peripheral wall aligned with the building opening upon which the fenestration product is mounted.
The invention further includes the method of manufacturing a fenestration product. The method includes the steps of thermoforming a first plastic sheet into a ring shape frame having a generally “U” shaped cross-section formed by an outer peripheral wall. A second plastic sheet formed of a material capable of transmitting visible light and is thermoformed into a dome having a central portion and a downwardly extending peripheral wall cooperating with the outer peripheral wall of the ring shape frame. The ring shape frame and dome are joined in a nested manner with the dome downwardly extending peripheral flange cooperating with the frame outer peripheral wall, where at least one of the ring shape frame and dome is formed with an integral outward extending flashing flange suitable for mounting the assembly on the building structure.
a is a cross-sectional view of an alternative embodiment of the
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to utilize the present invention.
Except where expressly indicated, all numerical quantities in this description indicating the amounts of material or conditions are understood as modified by the word “about” in describing the broadest scope of the present invention. Practice within the numerical limits is generally preferred.
Accordingly, a number of representative examples of the present invention are illustrated in the drawings and described herein. In the first example, skylight assembly 10 is illustrated in
In the first embodiment of the invention illustrated in skylight assembly 10, the frame 16 has a peripheral wall portion which in cross-section forms an inverted “U” shape having an inner wall portion 28 and upper wall 30. Extending radially outward from outer peripheral wall 24 is a flashing flange 32 which underlies flashing flange portion 22 of dome 14. Optionally, inner peripheral wall 28 extends downwardly into the building slightly below the level of the flashing flange 32 as illustrated in
In a typical 2′×4′ building opening size application, skylight 10 can be manufactured using a dome formed of acrylic having a wall thickness prior to thermoforming of 0.60 inches to 0.236 inches or the wall thickness capable of supporting an ultimate load needed in service or required by a regulation or an architect. These ultimate loads may include in excess of 20, 40, or 60 pounds per square feet as tested using procedure A of ASTM E330 after stabilization according to procedure A of ASTM D618. The frame may be formed of acrylic or a different plastic material such as acrylic polycarbonate, terephthalate, polyoxymethylene, polyolefin, and/or polyvinylchloride, since light transmission is not an issue. The wall thickness of the frame need not be thick, particularly when the frame filled with a rigid insulation foam 36. A wall thickness of the frame can range from 0.030 to 0.236 inches. Foamed insulation material such as polyurethane, expanded polystyrene, or polyisocyanurate can be used having densities between 1 pound per cubic foot and 40 pounds per cubic foot.
Preferably, the outwardly extending flashing flange 22 extends outwardly from a downwardly extending dome peripheral wall 28 at least 2″ to 9″ and more preferably, 3″ to 7″, in order to provide an adequate overlap to bond to the water barrier 38 mounted to the building sheathing 34 to allow adequate overlap with the roofing material 40 to prevent water leakage into the building opening. Flashing flange 22 also serves as a mounting flange for attaching the skylight assembly to the building roof sheathing 34. Preferably, corrosion resistant screws or nails are installed through the flashing flange portion 22 into the building roof sheathing 34. The mounting fasteners are preferably located significantly outboard of the dome downwardly extending peripheral wall 20 and well inboard of the outer peripheral edge of the mounting flange, but not necessarily aligned in a row, in order to minimize stress concentrations in the mounting flange caused by wind load on the skylight dome 18. Ideally, holes for fasteners do not have to be pre-drilled, that way assuring that any unused fastener holes do not provide an entry leak path for water. Holes for fasteners 42 may be drilled at the job site. In order to minimize screw pull out, the screws are preferably provided with a relatively large low profile head or be provided with an associated washer such as a compression washer.
a illustrates a cross-sectional view of an alternative embodiment of the skylight assembly. Skylight 44 is made up of three main components; a dome 46, a frame 48 and an insulating layer 50. Dome 46 and frame 48 are substantially similar to dome 14 and frame 16 described in reference to the embodiment invention of
Yet another variation of the skylight assembly is illustrated in
In the window assembly embodiment illustrated in
Window assembly 100 can be manufactured in standard basement window sizes. Windows can alternatively be designed to be mounted from the exterior or mounted from the interior of the building depending upon the architect's specification. The window assembly 100 can be attached to the wood framed window opening with conventional fasteners such as screws and nails. One or more bezels 126 may likewise be utilized either on the building exterior, building interior or both in order to further seal the joint between the building opening and the window assembly and to enhance the aesthetic appearance of the window.
The plastic sheets utilized to fabricate the three panels 102, 104 and 106 forming window assembly 100 may be of a variety of materials as described previously. While the frame material can be relatively thin, the panel facing the exterior of the building should be sufficiently thick to provide adequate security and provide acceptable aesthetic appearance. The plastic sheets may also be formed of composite sheets of plastic to provide desired enhancements. Examples of the composite sheets may include UV and/or heat transfer resistant films sandwiched between acrylic plastic. Another example may include an intrusion-resistant mylar film bonded between two thin sheets of polycarbonate plastic. It should be further appreciated that additional thin layers of thermoformed plastic material may be utilized in fabricating window 116 placed between dome 102 and inner layer 106 to increase the number of enclosed zones within the window to further improve the thermal resistance of the assembly.
Referring to
As an option, a sealed insulating unit 156 may be inserted adjacent to the interior layer 148. The sealed unit 156 may include a first central panel 158, a second central panel 160, a peripheral flange 162. The first central panel 158 is hermetically sealed to flange 162 creating an enclosed air space 166. Alternatively, a gas may be injected to space 166 to improve the thermal transmission resistance of the sealed unit 156. An example of the gas that may be injected is an insulator like argon. Alternatively, other insulators may be in the sealed unit. The insulator may include a vacuum, an aerogel, or a nanogel. The cavity 166 should be less than 0.625 inches in thickness and preferably less than 0.5 inches in thickness in order to prevent creation of convection cells within the cavity. The convection cells increase heat transmission. It is desirable that the flange 162 be less than 1.25 inch in length so that when placed adjacent to the interior layer 148, that they form a second air space 168 that may improve the thermal transmission resistance of the window assembly 130. Optional additional interior layers such as a second interior layer 170 may be inserted into cavity 146 to further improve the thermal transmission resistance of the window assembly 130. A coating, a deposition or a film may be applied to at least one of the components of the window assembly 130 including the dome 132, the interior layer 148, the sealing unit 156, and the second interior layer 170.
A cap 172 opposes the central panel 136 and provides closure to the cavity 146. The cap 172 has a peripheral flange 174 which is adjacent to the flange 142 of the dome 136. The cap 172 may also have positioning ribs 178 to assist in centering the cap in the opening in flange 142. The window assembly 130 including the dome 132 and the cap 172 are fastened to the concrete wall structure 134 using fasteners known in the art. An example of the fastener is a molly anchor 180. For aesthetic purposes, an interior trim bezel 182 may be attached to the cap flange 174 using a double stick transfer tape 184. It is understood that other means of attaching the interior trim bezel 182 that are known in the art may be used without exceeding the scope of the invention. Likewise, an exterior trim bezel 186 may be attached to the exterior of the concrete block structure 134 using a barbed insert 188. An example of the barbed insert 188 is commonly referred to as a “Christmas Tree”. It is understood that the barbed insert 188 may have individual prongs or be part of a more continuous ridge of barbed inserts. The window assembly 130 may optionally be insulated by injecting a foamed sealer 190, such as a foaming polymer like foamed polyurethane into a gap between the dome 132 and concrete block wall section 134 before application of the bezel 186.
The invention further includes a method of forming a fenestration product assembly. The method includes steps of thermoforming a first sheet of plastic into a ring shape frame having a cross-section and the general shape of an inverted “U”. A plastic dome is thermoformed from a second sheet of plastic material which transmits visible light defining a dome having a central region and a downwardly extended peripheral flange and a flashing flange extending outwardly from the outer peripheral wall. In one preferred embodiment of the method the central portion of the ring shape frame is cut out forming a central opening through which light can pass. The ring shaped frame and dome are then joined in a nested manner with the dome downwardly extending peripheral wall cooperating with the outer frame peripheral wall. Alternatively, the flashing flange may be omitted from the dome and provided on the ring shaped frame or flashing flanges may be included on both the dome and the ring shape frame.
The method of forming the fenestration product further includes the step of forming a transparent or translucent insulating layer which is interposed between the frame and the dome and bonded to at least one of the frame and the dome to define an enclosed space between the insulating layer and the dome to increase the thermal resistance value of the assembly. Alternatively, the method may include forming a second insulating layer interposed between the first insulating layer and the dome in order to define two separate enclosed regions between the dome and the two insulating layers to further increase the thermal resistance value of the assembly. It is understood that enclosed regions may include ventilating holes to allow relatively small transfers of gas to relieve pressure differentials or other issues associated with a sealed chamber exposed to temperature extremes.
The method may further include the step of filling the “U” shaped channel formed in the frame with the insulating material, such as a polymer foam which is preferably cured in place to substantially fill the “U” shaped trough defined by the frame.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
