| 摘要 |
PCT No. PCT/SE90/00016 Sec. 371 Date Jul. 9, 1991 Sec. 102(e) Date Jul. 9, 1991 PCT Filed Feb. 16, 1990 PCT Pub. No. WO90/09523 PCT Pub. Date Aug. 23, 1990.A screw rotor machine which incorporates a sound silencing device in the vicinity of the inlet and/or outlet port. The sound silencing device comprises a De Laval nozzle (8) having a valve body (9) which is movable axially in relation to the nozzle. When the machine is shut-down, the valve body (9) lies sealingly against the opening (8A) of the nozzle. When increasing the capacity of the machine to full load, the valve body (9) moves in the opening direction under the influence of a damping force and against the action of a substantially constant spring force (14), so as to maintain a flow rate immediately beneath the sound of speed in the smallest area (8A) of the nozzle (8).
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