| 摘要 |
<p>The vent assembly, mounted in a door or a window, is normally open to allow ventilation. It has an integral sound detector which closes the vents on the inside and outside of the assembly if the external noise level exceeds a predetermined level. The vents are vertical slides which are connected via a common gear arrangement to an actuating lever (23). The lever (23) is operated by a rod (33) connected to the armature of a solenoid (31). The solenoid has a spring return mechanism (34) which opens the vents automatically when the solenoid is de-energised. The supply (36) is connected to the solenoid via an on/off switch (37) and a relay (35). The relay is operated by the noise level detector (32).</p> |
