| 摘要 |
<p>1,175,194. Dynamic compressors. BROWN, BOVERI & CO. Ltd. Dec.20, 1966 [Dec. 22, 1965], No.56950/66. Heading F1C. [Also in Division G3] A controller with separate means for applying proportional feedback and reset to a controlling member; and used to prevent surging in compressors, has a connection between the reset means and the controller output providing a fixed impedance to flow and a connection between the feedback means and the output providing a higher impedance to flow in one direction than in the other whereby the feedback time-constant when regulating in one direction is reduced to a fraction of the feedback time-constant when regulating in the other direction. The quantity to be regulated is applied to a spring-loaded bellows 4 actuating a nozzle and flapper valve 8 through a beam 15. Compressed air is supplied to the valve from a line 3 via a throttle 10 and the pressure upstream of the valve is amplified at 11 to provide an output pressure in a line 2. To provide the difference in time-constant, air enters a feedback bellows 7 via throttle 13 during periods of increasing output pressure but escapes rapidly through a non-return valve 14 when the output pressure falls, the controller being reset by a further bellows 6 and throttle 12. If the quantity to be regulated varies sinusoidally, the output falls in a sawtooth-like curve and may be used to operate a blow-off valve on the compressor. A variable resistor and rectifier may replace the throttle 13 and valve 14 if electrical control is required.</p> |
