US Patent 10094140 Door opening and closing structure

The invention relates to a door opening and closing structure including a door plate, a transverse bar, a zipper and a pulling string. When a tension is applied on the pulling string and the tension is greater than a gravity of the transverse bar and at least a portion of the door plate, and the at least a portion of the door plate is driven by the transverse bar to move along the extension direction to form an opening. When the tension is less than the gravity of the transverse bar and the at least a portion of the door plate, the door plate is driven by the transverse bar to move along the gravity direction to reduce the opening.