| 摘要 |
The air pressure in the room (11) is measured by a differential pressure sensor (6) in comparison with the outside air admitted through a valve (9) to a reference container (8). The interior pressure variations are compensated by a controller (60) which adjusts the setting of a throttle (2) in the outlet (15) from the ventilator (1). The controller (60) consists of a summing amplifier (63), window discriminator (64) and output stage (66) controlling a motor (5) with limit switches (4) and position feedback (12,68) from the throttle adjustment cam (3). The delay time constant introudced by the reference system (8,9) is at least 15 and pref. about 24 minutes. USE/ADVANTAGE - Relief of headache, migraine, acute rheumatic pain and circulatory disorders in stormy weather conditions. Ill effects of barometric pressure variations are either eliminated or reduced.
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