The following is a tabulation of some prior art that presently appears relevant:
Overhead doors are used for a variety of applications, from refrigerated area closures to light aircraft hangar doors. Design requirements include thermal insulation, structural resistance to lateral loads, such as pressure induced by wind, and security requirements.
Existing overhead door designs are classified, in U.S. patent Ser. No. 10/428,566, into two general categories: (a) single and dual panel designs and (b) designs primarily comprised of a plurality of panels or slats which are connected by belts or hinge mechanisms. General category (a) is further defined to include: (a1) rigid panel designs, (a2) flexible single sheet panel designs and (a3) flexible multi-layer panel designs.
Overhead door designs may also be classified by the method of securing the door in its open configuration: rolled into a substantially cylindrical configuration (roll-up), or supported in a substantially horizontal configuration. The remainder of this discussion is concerned with only the roll-up configuration. Existing roll-up door design art generally falls into design category (a2) single flexible sheet, (a3) flexible multi-layer panel or (b) multiple connected panels or slats.
(a2-1) Complete recent designs of single flexible panel roll-up overhead doors are represented by U.S. Pat. Nos. 5,129,442, 5,632,317, 7,131,481, 7,231,953, 9,637,972 and U.S. Patent Application Publications 20160177624, 20160273824, 20160348424, 20160348430, 20160376841. A challenge shared by all of these designs is resistance to lateral loading created by winds impinging on the respective door. Flexible panel designs containing minimal to nil intermediate stiffening members resist lateral wind loads through panel tensile membrane stress induced by lateral deformation of the panel when loaded. Nearly all of these designs contain provision for restraining the membrane stresses.
(a2-2) U.S. Pat. No. 5,129,442 presents a design where all resistance membrane stress is transmitted vertically to top and bottom structures. In this case moderate wind loading could result in separation of the panel sides from the door frame. U.S. Pat. No. 5,632,317 presents a similar design with the addition of a single horizontal “wind bar” at mid-door height. In this case, the added bar relieves some of the lateral deformation induced stress. However, moderate to high wind loading could create a side separation problem. U.S. Pat. Nos. 7,131,481 and 7,231,953 present designs where relatively widely spaced horizontal stiffener struts are incorporated into the panel design and “wind locks” (horizontal panel displacement constraints) are added to the panel vertical sides. U.S. Pat. No. 9,637,972 presents a similar design where the horizontal struts are replaced by two separated vertical guide channels. Both of these designs result in a relatively greater ability for lateral load resistance with the penalty of greater weight and complexity.
(a2-3) Various modifications to parts of door designs are disclosed U.S. Pat. Nos. 6,152,207, 8,291,960, 9,187,953 and 9,260,911. With few exceptions, the modifications suggest more efficient or simplified details for increasing single flexible panel door design structural resistance to lateral loads.
(a2-4) U.S. Patent Application Publications 20160376841, 20160348430, 20160348424 and 20160177624 present relatively simple unstiffened panel designs where the panel vertical edges have horizontal displacement restraints which slide within vertical guides. This results in relatively simple and inexpensive designs with relatively low resistance to lateral wind loads.
(a3) A roll-up flexible multi-layer panel design is disclosed in U.S. Pat. No. 6,065,525. In this design, a planar flexible sheet is intermittently connected to a flexible corrugated panel where the axes of corrugations are oriented horizontally. An advantage of this design is that the corrugated panel more efficiently resists lateral wind loads through bending of the corrugations. However, due to the intermittent connection of the two panels, the full composite bending strength of both flexible panels is not developed. The relatively small increase of this dual panel design's ability to distribute lateral wind loads is not justified by the increased complexity and weight of the design.
(b) Overhead roll-up door, multi panel designs are ubiquitous, usually employed where security is a significant design requirement. U.S. Pat. Nos. 5,172,744, 6,883,577, 8,684,064, 10,344,527 and U.S. Patent Application Publication 20190071923 depict designs in this category. As described in most of these designs, the individual panels are compact, having large aspect ratio and bending stiffness with resulting favorable resistance to lateral wind loads. This results in relatively heavy door designs and, due to the large number of panel-to-panel connections, non-optimal weather tightness and thermal insulation.
Arendts (1969), as summarized in Arendts and Sanders (1970), shows that structures, such as box girder bridges, consisting of two relatively thin elastic sheets connected by a plurality of transverse webs, theoretically and actually behave as sandwich plates with orthogonally differing core transverse shear properties. Such a structural panel may be modified, through hinging the web-sheet connections, so that it is flexible. Overall stiffness and strength of the panel is not significantly reduced by hinging the webs and stability is achieved through proper support of the overall structural system. Arendts, in U.S. patent Ser. No. 10/246,932, discloses a deployable structural system consisting of two relatively thin elastic sheets connected by a plurality of elongated parallel web panels. These connections are hinged to form a composite panel which may be elastically transitioned from a nearly planar configuration to a substantially cylindrical rolled-up configuration. Two embodiments of a roll-up door design, utilizing this deployable structural system, are disclosed herein. Advantageous properties of this design are summarized below.
Existing roll-up door design art suffers from some deficiencies:
The present door design embodiments, in the closed configuration, have large composite thin sheet bending stiffness with resulting large allowable transverse load to structure weight ratio. Additionally, the cellular nature of the designs results in naturally large transverse heat flow insulation.
These deployable shell roll-up door design embodiments have the following advantages when compared with other existing roll-up door system designs:
(a) Very large allowable transverse load to structural weight ratio,
(b) Very large lateral stiffness to structural weight ratio,
(c) Weather tightness,
(d) Ability to provide closure for pressure boundaries,
(e) Native transverse heat flow insulation due to constrained air in the panel void spaces,
(f) Ability to quickly and quietly transition the door between closed and open configurations.
In the drawings, closely related figures have the same number but differing alphabetical suffixes.
Overall views of the first embodiment are illustrated in
Details of the door panel assembly are illustrated in
A support and guide roller 22, which is connected to the door mount and support assemblies 12, is provided. It is noted that this roller does not transmit a large radial force to the rolled elastic sheets since shell transverse shear force is absent for circular cylindrical bending displacement of the thin elastic sheets.
The first embodiment contains two nearly identical mount and support assemblies located at both ends of their respective mandrels. Designs of the assemblies differ due to inclusion of a weight counterbalance spring mechanism. The designs are designated “side A” and “side B” where side A includes a counterweight spring pretension and frame anchor mechanism and side B includes a spring-axle connection. The first embodiment support assembly designs constrain all radial displacement of the axle-mandrel assembly.
A side view of side A support assembly is shown in
A side view of the side B support assembly is shown in
Overall views of the second embodiment G2 geometry are given in
Details of the door panel assembly are illustrated in
A support and guide roller 22, which is connected to the door mount and support assemblies 52, is provided. It is noted that this roller does not transmit a large radial force to the rolled elastic sheets since shell transverse shear force is absent for circular cylindrical bending displacement of the thin elastic sheets.
The second embodiment contains two nearly identical mount and support assemblies located at both ends of the mandrel. Designs of the assemblies differ due to inclusion of a weight counterbalance spring mechanism. The designs are designated “side A” and “side B” where side A includes a counterweight spring pretension and frame anchor mechanism and side B includes a spring-axle connection. The second embodiment support designs allow for horizontal displacement of the mandrel-axle assembly.
A side view of side A support assembly is shown in
The significant difference between the first and second embodiment supports is that, for the second embodiment, the axle-mandrel assembly moves horizontally relative to the framework via a linear bearing assemblies and is regulated by cam systems. The reason for this movement is to assure correct tracking of the web rollers during operation of the door. A linear bearing assembly consists of two linear bearings 74 guided by a linear bearing shaft 75 and affixed to a linear bearing support 78 which, in turn, supports the frame bearing 36. Horizontal movement of the axle is controlled by a grooved cam plate 82,
Side and cross-section views of the second embodiment side B support assembly are shown in
The elastic surface sheets, 23, 61 and 24, 62, may be comprised of homogenous metallic material or of composite fiber reinforced polymer (FRP) construction. The webs, 25, 63, are subject to only in-plane stresses due to bending stress relief of the hinges 29, and may thus be constructed of light homogeneous materials or a FRP wrapped core. The hinges may be conventional mechanical hinges or constructed of flexible polymer composite. Various methods may be employed for hinge attachment to sheets and webs, including mechanical (rivets or spot welds) or adhesives. Also, the webs may be designed to include the hinge elements so that the only assembly attachments required are web-to-sheets.
Operation of both door embodiments is very simple where a torsional force is applied to either end of the axle which results in rotation of the axle-mandrel assembly and associated vertical motion of the door.
A representative section of the rolled-up door is shown in
Maximum elastic strain, e, in a circular cylindrically bent thin elastic sheet is given by the following well known relationship:
e=t/(2R),
where t is the sheet thickness and R is the cylindrical bend radius of the sheet. Maximum open embodiment strain, emax, is then,
emax=max{ti/(2Ri),to/(2Ro)}.
From this relationship, design t/R ratios are determined by equating emax with the sheet material design strain, as determined in the preceding paragraph.
After selection of Ri, Ro and web dimension W, constants k and C are computed according to relations 101,
For first embodiment designs (geometry G1), the clear opening height, see
Due to its very large lateral load resistance to weight ratio and weather tightness, the deployable shell is an excellent candidate for retractable roof design bases.
An additional retractable roof application embodiment is illustrated in
A number of advantages are evident in the first and second embodiments described above:
(a) Very high stiffness and strength to weight ratios of the closed configurations enable light weight embodiments to carry large environmental transverse loads, such as pressure induced by wind.
(b) Embodiment continuous sheet surfaces enable the closed embodiments to be weather tight and capable of forming static pressure boundaries.
(c) Air confined in the cells of the closed configurations enables natural insulation of transverse heat transfer in the embodiments.
(d) Embodiment construction is extremely easy with no requirements for use of specialized equipment.
(e) Embodiment installation and operation utilizes existing commercially available equipment.
Two deployable shell roll-up door embodiment designs are disclosed herein. The embodiment designs are simple in concept and construction, yet have many potential uses which take advantage of the designs' unique capabilities:
Although the above discussion contains many specificities, these should not be construed as limiting the scope of the embodiments, but as providing illustrations of some of several possible applications.