| 摘要 |
A lightweight, high speed roll-up door, or curtain, is unrolled from and rolled upon a cylindrical tube disposed above or within an opening in a wall by a drive motor/drive shaft combination coupled to one end of he tube. A non-rotating support shaft is attached to the other end of the tube which has disposed within respective ends thereof first and second coiled springs. A pair of belts are coupled to lower opposed ends of the door and are wrapped around respective pulleys positioned at each end of the tube and mounted to the drive and support shafts, respectively. With one end of each of the coiled springs coupled to the tube and each of the other ends respectively coupled to one of the pulleys, the coiled springs urge the two pulleys and the tube in opposite directions of rotation to maintain the door in a tightly stretched condition. Changes in the effective radius of each of the pulleys as the belts are unwound/wound as well as changes in the effective radius of the tube as the door is unwound/wound counterbalance the door's weight by compensating for changes in the weight of the withdrawn, or extended, portion of the door to ensure high speed door operation regardless of the length of door withdrawn from the tube. |
