| 摘要 |
A roof structure to protect a crop growing area includes a retractable roof membrane or curtain that defines pitched sections of roof. The membrane is supported on wires and extends across the valley between pitched sections. Apertures are provided in the membrane to allow water to pass through the membrane. A gutter may be disposed in the valley beneath the apertures to collect the water and discharge it away from the crop growing area. A rotating drive tube mounted on an interior rafter has cables connected to the drive tube with a spring connected to each cable to regulate minimum tension of the cable. The drive system is positioned so that the membrane adjacent to the drive tube on the interior inclined rafter is able to travel the same distance as the second membrane from the drive system. The rafter contains profiles to allow the stationary end of said membrane to be attached to said rafters using both a round tube and a "C shaped profile to be installed continuously along said rafter to provide a water tight connection between said rafter and said membrane. The rafter also contains clips which provide the ability to restrict the guide wires which suspend said membrane in such a way that wires are clamped to inhibit vertical, lateral and horizontal movement at interior rafter locations with a different clamp at a rafter adjacent to a perimeter wall of the structure such that the guidewire can move only perpendicular to the rafter. Guidewires are typically supported by trusses but now can be alternatively supported by a network of flexible cable or rods at a lower cost. To allow for ventilation and rain protect simultaneously, a secondary membrane is installed below a opening in the roof, with the secondary membrane transporting rainwater which entered through the roof opening down into a gutter. To maximize the reduction in temperatures at the crop level during the summer, and to hold the heat closer to the plants during the cold winter conditions winter daytime temperatures, the upper retractable membrane is white and a secondary retractable membrane located closer to the plants is clear. |
