| 摘要 |
Column (30), sited at junctions (14) where vehicles (20,22) are halted by traffic signals (16), has hollow case, internally sound-proofed, with electrically driven fan (34) sucking air through top intakes (28) and expelling it through low level vent (26). Power supply is available (32) at adjacent traffic signal control cabinet (18), which also accommodates filter column's control circuits. The intakes (28) are placed well above the level at which the average passer-by breathes, i.e. upwards of 1.5m. Fan operation is initiated by time-delayed ultra-sonic, infra-red or radar sensors (38), which detect the presence of standing vehicles, and inhibited by a humidity sensor (40) when humidity is at such levels (e.g. over 70%) as to deactivate the activated carbon filter, which, with fine and particle filters, constitute the air purifier. Opt., fan operation is linked to the red and amber phases of the traffic signals. Opt., columns are installed along main thoroughfares at pedestrian refuges, bus shelters, etc., forming part of their structure. Operation is initiated when a pedestrian enters and the purified air is discharged into the shelter, e.g. via roof vents. |
