| 摘要 |
A ventilation control device comprises an aperture restriction member, movable to vary the effective cross-section (3) of a ventilation passageway, first control means (8) coupled to the aperture restriction member and operable to control the positioning of that member so as to impose a limit upon the said effective cross-section whilst permitting movement of that member in a direction which does not cause the said limit to be breached, and second control means (9) which can be operated selectively to cause such movement of the said member. This provides for greater flexibility in the control of the ventilation of premises. The first control means (8) may be an automatic actuator such as a braid whose length alters with changing humidity, thus rotating lever (18) and spindle (6) to open flap (4). The second control means (9) has an output rod (20) acting on a link (22), to rotate both levers (25) and (28), to open both flaps (4) and (5). |
