Patent Application
20070062567
The present invention relates to a low-profile, polygonal, pole-supported tent whose modular bays are joined by a water-shedding keder rail and wherein joints between bays are sealed against water by flaps adjacent the edges of the bays.
Conventional tensile structures and tents that span large areas must be fabricated in modules to facilitate transport and handling. Modularization of the membrane presents challenges for joining it into one weather-proof membrane. Field joints are generally labour intensive, prone to leaking, and often unsightly. Field joint covers made to weatherproof lace line and other joints often employ hook and loop fasteners (i.e. Velcro) or snap, hook, and cable fasteners which are extremely sensitive to accurate indexing and almost always set up conditions for shear forces to present wrinkles along the seam cover material. Fabric joints on frame tents are made at the beams and are often prone to leaking water. However, such beams are not used in a pole supported tent, necessitating beam-free joints.
A keder, or keder strip, is a thickened edge on a membrane such as a sail, tent canopy, etc., which, when inserted into an extrusion made to accommodate it, (e.g. a keder extrusion, keder beam or keder rail) serves to fix the membrane to the extrusion. The keder extrusion has at least one channel, having a narrowed elongated opening, that receives the keder. Since the width of the keder is greater than that of the elongated opening, the only way it can be inserted or removed is to slide the keder along the channel and out one of the ends. The keder beam, rail or extrusion made to hold the keder can be made from any one of a variety of materials, but lately extrusions are considered to be the favored option.
The use of keder extrusions to join tent membranes is known in the art. However, their use is limited because they are prone to leaking. This makes keder extrusion particularly unsuitable for joining tent canopy modules at low points of a tent canopy. For this reason keders are not used to join membranes in canopy “valleys”.
As well, the height of a pole tent is dictated by the minimum slope acceptable to ensure proper drainage. The minimum slope is found on the fall line at the corners of rectangular tents. The wider the tent, the higher the peak(s) required to maintain the minimum acceptable corner slope. Higher peaks require longer poles and/or beams, adding to the weight, size and cost of the tent. It also means that the tent is more vulnerable to wind, therefore requiring more anchorage, thereby further increasing the weight, size and cost of the tent.
Accordingly, it is an object of the present invention to provide a tent structure with an effective membrane joining system that is easy to manufacture and erect. It is a further object to provide a tent with low wind profile. It is a further object of this invention to provide a tent with excellent water shedding and drainage characteristics. It is a further object to provide a tent with fabric tensioned to the level of permanent tensile structures without the complex mechanical devices and means to erect it, but instead with a simple mechanical means to introduce said tension in a safe manner by only one person. It is a further object of this invention to provide a tent with minimal ground anchorage and maximum span between side posts.
According to the invention a tensile pole tent, having two centre poles and a polygonal projection in plan view, is provided, having a flexible membrane canopy with perimeter catenaries, and corner posts (perimeter columns) to support the perimeter catenaries. The membrane is made up of two modules, each supported by a centre pole, and each having a long edge. The long edges of the modules are joined to one another along a membrane interface or field joint consisting of, for example, a novel water-shedding keder rail, or a zipper or daisy chain grommets and loops. The membrane interface can be sealed against precipitation by cover flaps that extend upwards from the membrane.
The interface bisects the tent in between the centre poles.
The membrane interface or field joint is provided by one of several means, for example:
Although the keder rail is described in this application in the context of a tensile pole tent structure, it will be readily apparent to persons skilled in the art that it has numerous additional applications and that it is not limited to tensile pole tents. The keder rail is essentially a means for providing a leak-proof joint between adjacent membranes or sheets and, therefore, is applicable to a wide variety of tents, including frame tents, tensile structures, awnings, canopies, etc. The keder rail may also be used in permanent membrane structures.
Each one of the above field joint means (zipper, grommet and loop, Velcro, keder rail or extrusion) can be sealed with a pair of cover flaps symmetrical to the centre line of the field joint. The seam seal works by engaging the tension in the membrane itself to press the opposing flaps together in an abutting “prayer” position, thereby covering the field joint and shielding it from exposure to the elements. Because the flaps are not connected to their opposite member (i.e. they are in contact but not actually joined) they are able to slide against one another. Therefore, no shear forces transmitted between adjacent membrane modules and therefore there are no wrinkles in the membrane or the flaps. So the seal is smooth and attractive, unlike prior art seals (e.g. Velcro flaps).
Employing a heavy weight fabric strip further enhances the pressure between the two strips. The flaps may be made of any suitable material, including plastic, PVC, rubber, etc. Employing a PVDF or Teflon finish on the inner surfaces of the flap helps to guard against capillary action.
The novel keder rail and the “prayer” cover flaps of the present invention permit adjacent tent membrane modules to slide relative to one another and therefore do not transmit shear forces. This contributes to a wrinkle-free tent membrane.
The novel keder rail and the “prayer” cover flaps of the present invention additionally provide a water tight interface between adjacent membrane modules. This makes it possible to join the tent modules in the valleys, or low points of the membrane, rather than at the pole tops and ridges as in the prior art (i.e. where field joints are limited to relative high regions of the membrane). By joining tent modules at the pole tops and ridges, the cost of manufacture of the tent is increased because of the extra terminations at both the side and centre poles.
Furthermore, the novel keder rail and the “prayer” cover flaps make field assembly much quicker as joining modules requires no more lacing, and the need to Velcro or snap sealing flaps down over the membrane joints is eliminated. This is very important in portable structures since installation and take down may be repeated hundreds of times during a tent's lifetime.
Further features and advantages will be apparent from the following detailed description, given by way of example, of a preferred embodiment taken in conjunction with the accompanying drawings, wherein:
FIGS. 2(a-d) are plan, perspective and side views of an assembled tent;
Referring to
Referring to FIGS. 2(a-d) and 12, the membrane 40 of the tent 10 is made up of two modules, or bays, 70. The modules 70 are joined to one another along an interface or field joint 80, the details of which will be described more fully below. The interface 80 passes through a valley, (i.e. low point) of the membrane 40. The tent 10 has two centre poles 90, each supporting a respective one of the peaks 20, and eight corner posts 100 supporting the perimeter catenaries 50 at ends thereof. The membrane 40, the perimeter catenaries 50, and the interface 80 are tensioned by the anchor lines 30, producing a tensile structure. The tent 10 has no beams.
The distance from the peak or centre pole of a tent to the furthest boundary (i.e. corner) on a square or rectangle is farther than it would be on a polygon having more than four corners (assuming the comparison is between two tents covering an equal area when viewed from directly above). This is because in hexagons, octagons and other polygonal tents having more than four corners, the corners are in essence “truncated.” Since the slope of the membrane decreases exponentially with distance from the peak or centre pole in tensile tent structures, the drainage is better on truncated shapes than on 90 degree corners (i.e. the distance from peak to corner is reduced, thereby resulting in a steeper membrane slope near the corners). Consequently, by employing truncated shapes such as octagons or hexagons, the centre pole(s) and peak(s) may be lowered. The advantages of this are legion: ease of erection of a much shorter centre pole, lighter weight, smaller section modulus, lower cost of the centre pole(s); less fabric employed in the manufacture the tent; less membrane weight to lift during erection; lower membrane cost; wider modules or bays possible with improved drainage, reduced wind profile, resulting in better weather performance and making possible the use of lighter materials, fewer anchors, less hardware and fewer side support poles, with attendant lower costs and improved ease of assembly.
The distance from the peak or centre pole of a tent to the corner can also be reduced by using more than one centre pole. Accordingly, the illustrative embodiment of
As will become apparent in the description below, the novel leak-resistant membrane interface 80 of the present invention makes it possible to join membrane modules at a low point of the membrane, essentially bisecting the tent between the centre poles. This makes it possible to design a low-wind profile tent without many of the disadvantages of the prior art (i.e. complex and expensive membrane construction, difficult and labor intensive set-up and take-down, aesthetically compromised membrane, etc.).
In the preferred embodiment, the keder rail 110 is flexible such that it can conform to the curvature of the tent membrane. However, in other applications, the keder rail 110 may be rigid (e.g. when it forms a part of a structure, for example, a beam).
Prior art keder extrusions are flat-surfaced. This means that a water droplet running down the fall line on the upper surface of the keder extrusion eventually encounters a joint between adjacent keder extrusions. The droplets run into the crack between adjacent keder extrusions and leak into the tent. By curving the upper surface 120 of the keder rail 110, water droplets following the fall line run off to the side of the keder rail. The only water that will intrude through the joint between adjacent keder rails is that which falls upon a small, approximately triangular region immediately above the joint.
Referring to
Referring to
Referring to
The steeper the angle which the keder rail 110 experiences when the tent 10 is erected, the greater the degree of curvature of the convex surface 120 required to ensure that water runs to the sides of the keder rail 110.
Although the keder rail 110 is described herein the context of a tensile tent 10 structure having no beams, it will be readily apparent to persons skilled in the art that the novel keder rail of the present invention may itself take the form of a beam, post or other structural member. Such a structural member would exhibit the same water-shedding characteristics as the keder rail 110 of
Referring to
In the preferred embodiment, the keder rail 110 of
Referring to
For the sake of illustration, the modules 70 shown in
Referring to
Referring to FIGS. 2(a-d), 3-8 and 10, depending on the desired characteristics of the interface 80 between modules 70 of the membrane 40, the interface 80 can be achieved with or without the cover flaps 230, and using one or more of the following mechanisms, alone or in combination: the keder rail 110; and one or more prior art joining means such as eyelet and lace, zippers, Velcro, conventional keder extrusions, etc. In addition to the water-shedding characteristics, the keder rail 110 does not transmit shear forces between adjacent modules 70 and therefore does not result in wrinkles in the tent membrane 40, thereby improving the aesthetics of the tent 10. The kidder rail 110 is also easier to set-up than, for example, eyelet and lace because it is not as sensitive to accurate indexing.
The interfaces 80 described in
Accordingly, while this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.
