| 摘要 |
An electrical device for evaporating a volatile liquid (for example an air freshener) into a room employs a wick (14) which extends upwardly from a container of the volatile liquid. A ring heat (16) is in the vicinity of the end of the wick, and assists the evaporation. Vapour escapes from the device through an aperture (10) above the wick, in a casing. The vapour emission rate is controlled by a user, who operates a control member in the casing, to alter the vertical position of a tubular body (18). Vapour may flow from the wick to the exterior through the tubular body (18), and then through the aperture (10). However in all positions of the tubular body vapour may also flow to the aperture, and thence to the exterior, by an auxiliary route, not through the tubular body. It is found that the provision of this auxiliary route for vapour significantly improves the performance of the device. The tubular body (18) comprises an upper surface (31) comprising a wall (32) and apertures (33). The wall (32) together with the apertures (33) ensures that any unevaporated volatile liquid is directed back towards the heater.
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