Automatic closure with locking of ventilation flap or window

摘要

The aperture in the wall (7) is covered by a hinged flap (1) opening inwards with a cord (2) running from an attachment (3), at about one-quarter of the width from the hinge, over a roller (4) to a clock-controlled spring motor (6). The motor can be controlled by timer, temp. detector, smoke detector, wind speed detector, etc.About three minutes after being opened the flap is closed by release of the energy stored in the spring by the action of opening. The open position is stabilised by an angled strip of springy sheet metal (8).