Patent Application
20060075694
Non-Applicable.
This invention relates to an aerodynamic means that mitigate wind generated vortices and uplift loads on the roof perimeter area of a building, in a simple, effective, and economical way, applicable for both new constructions and retrofits of existing buildings.
Current roof construction practices normally result in a roof perimeter configuration that tends to generate strong edge vortex and subjects the roof perimeter area to severe uplift and high risk of wind damage. Structural methods have been traditionally used to counter the severe uplift force and mitigate the risk of wind damage, while few aerodynamic methods have been recommended to reduce the uplift force. Banks et. al. described in U.S. Pat. No. 6,601,348 (2003) various types of wind spoilers supported above the roof plane to mitigate roof edge vortex. However, the apparatus is rather complicated in shape and structure, and is susceptible to wind damage itself because the raised structure subjects itself to accelerated airflow across the roof edge. In U.S. Pat. No. 4,005,557 (1977), Kramer et. al. described designs for a roof wind spoiler system claimed to be used near roof comers. The limited breadth of the apparatus impedes its effectiveness and causes higher wind loads on the adjacent segments of a roof perimeter where the apparatus does not extend. Ponder disclosed in U.S. Pat. No. 5,918,423 (1999) a wind spoiler ridge cap that is designed for roof ridges. The roof edge structure disclosed herein utilizes edge serration and face perforation to disrupt vortex formation, and is continuous along a roof perimeter or at least substantially extends from the roof comers towards the middle part of a roof edge. While the examples illustrated in this application are primarily for flat roofs, the conception and spirit herein demonstrated is suitable for both sloped and flat roofs. U.S. Pat. No. 5,414,965 (1995) of Kelley et. al. includes a drain-through gravel stop with limited face perforation for rainwater drainage, but the porosity is far from sufficient for airflow, and it does not provide edge serration, to effectively suppress roof edge vortex.
In U.S. Pat. No. 6,606,828 (2003) of this applicant et al., a series of roof edge configurations are recommended for use to mitigate vortex and high uplift in flat-roof perimeter areas, where the concept is one of coordinated exterior curvature design for a roof edge system. The present invention discloses a distinct roof edge apparatus that utilizes roof perimeter plates having face perforation and/or edge serration, which disrupt and mitigate roof edge vortices and thus reduce uplift force and wind scouring on a roof.
This invention discloses an aerodynamic means that mitigate wind generated vortices and uplift loads on the roof perimeter area of a building, in a simple, effective, and economical way, applicable for both new constructions and retrofits of existing buildings. This is achieved by using an elongated plate-like device generally having face perforation and/or edge serration and being appropriately mounted along roof perimeters. The face perforation provides air permeability facilitating a pressure equalization effect while the edge serration provides a non-straight, zigzag, edge shape leading to a flow-disorganizing effect, each of which increases small-scale turbulence entrainment, prevents or interrupts the vortex from formation along a roof perimeter. Such a roof edge device is generally referred to as roof edge vortex suppressor in this application. The specific configurations exemplified herein pertinent to this invention are primarily for perimeters of flat or low-slope roofs, while the spirit and principles of the present invention are applicable for both sloped and flat roofs. It is prudent that modifications be made according to the demonstrated concepts and principles when other types of roofs or roof edge constructions are encountered.
Several objects and advantages of the present invention are:
Further objects or advantages are to provide roof edge devices which protect a roof perimeter from wind and rain damage, and which are still among the simplest, most effective and reliable, and inexpensive to manufacture and convenient to install. These and still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.
The specific layout, number, shapes and sizes of the distributed perforation-holes are not of primary significance, as long as the overall porosity resulting from the face perforation is sufficiently large to provide desired air-permeability. Similarly, while deeper serration or indentation are generally preferred by using larger sizes for the projections and notches of the zigzag edge, their specific layout, number and shapes are not of critical significance. Triangular, rectangular, trapezoidal, semi-circular and semi-elliptic shapes etc., for example, are all permissible without compromising the functionality described herein. It is also allowable that the perforations, projections and notches have different shapes and sizes in the same vortex suppressor assembly. The choices may be made in combination with aesthetic considerations.
A roof edge vortex suppressor may be mounted on and secured to a roof edge with any appropriate means that does not negatively affect its functionality. In this example, the vortex suppressor 10 extends downwardly in parallel with wall surface 201, and bends back upwardly and then inwardly to conform to the wall surface 201 and roof plane 200, forming a mounting base 18 for the device being secured to the roof perimeter with fasteners 210. The method to mount and secure the vortex-suppressing device to the roof perimeter as illustrated herein is merely an example, with many alternative common methods being possible, and ought not to limit the scope of this invention. Roof membrane 202, insulation material 204, substrate 206 and wood nailer 208, being examples of common roof components, are included in the drawings herein merely to illustrate their relationships with the vortex suppressor that is the subject matter of this invention.
Utilization of both edge serration and face perforation is generally preferred; however, use of only edge serration or face perforation is also allowable. As an example, the embodiment illustrated in
A edge vortex suppressor described herein provides protection against wind and rain damage for a flat roof when the apparatus and its geometric relationship with the roof perimeter are configured in accordance with the spirit of this invention, as exemplified herein in the specification and governed in the appended claims. The examples given in this application are merely for the purpose of describing the invention and should not be construed as limiting the scope of the invention or the applicable variations of configuration according to the spirit of this invention. It is emphasized that the geometric elements for edge serration or face perforation need not to have the same shapes or a strictly regular spatial pattern as those illustrated herein. Many other shapes such as triangles, rectangles and trapezoids, arranged in various patterns, can also be used for forming serrated edges and/or perforated faces according to the spirit of the invention disclosed in this application without compromising the function of the vortex suppressor.
An embodiment of this invention is a passive flow control device for roof edges. Once configured and installed properly, it stays functioning in such a way that it mitigates vortex formation at a roof edge and reduces uplifts and wind scouring on the roof, whenever the wind blows towards a building bearing atop such roof edge devices, and requires no active operational intervention.
It is apparent that roof edge vortex suppressors of this invention provide advantageous devices for mitigating roof edge vortex and roof uplift, and are still among the simplest, most effective and reliable, inexpensive to manufacture and convenient to install, with little, if any, maintenance requirement.
Compared to the prior art, the present invention provides a unique one-piece, self-supported, substantially simpler and stronger structure that can be conveniently fastened to the roof edge with superior stability, while at the same time ensures a key function of suppressing roof edge vortex. In addition, this present invention also provides a function of being an effective roof gravel stop and an aesthetic edge termination fascia.
Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Various changes, modifications, variations can be made therein without departing from the spirit of the invention. Roof edge vortex suppressors can be made of any reasonably durable material with any appropriate means of fabrication as long as a configuration according to the spirit of this invention is accomplished to support the described working mechanism and to provide the associated functionality. Any appropriate conventional or new mounting method can be used to secure a roof edge vortex suppressor to a roof perimeter without departing from the spirit of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
This application is entitled to the benefit of Provisional Patent Application Ser. No. 60/613,354, filed 2004 Sep. 27.
| Number | Date | Country | |
|---|---|---|---|
| 60613354 | Sep 2004 | US |
