| 摘要 |
<p>The invention relates to a ventilation trap door which is provided with an air filter (3) and a closable gate (2). The outer surface (4) of gate (2) is fitted with a chute-like element (5) to form a channel (6) between itself and outer surface (4) of gate (2), or gate (2) itself is provided with a channel, adapted for passing air from one section of gate (2) to another and further through gate (2) by way of an opening (7) made therein. Channel (6) is made of a sound-absorbing material or it is provided with a sound-absorbing material (8). In opening (7) of gate (2), in front of the opening on inner surface (10) of gate (2), or in channel (6) there is fitted a regulator for controlling the air flow.</p> |
