GB957884A - Rotary compressors - Google Patents

Abstract

957,884. Centrifugal compressors. SULZER FRERES S.A. Jan. 14, 1963 [Jan. 25, 1962], No. 1639/63. Heading F1C. [Also in Division G3] In a rotary compressor of the kind in which the rotor blades have substantially radial inlet edges and the rotor has a semi-axial or radial outlet, or, in the case of a multi-stage compressor, at least the first stage rotor is so formed, surging is prevented by throttling the flow at the rotor inlet by means of a restrictor which adjustably narrows the flow path in a substantially radial direction, thereby limiting the entry cross-section into the rotor at least approximately circularly. In the compressor shown in Fig. 4, the throttling is done by a ring 20 of natural or synthetic rubber which can be inflated from the size shown in the lower half of the figure to that shown in the upper half so as to extend into the intake channel 4. The liquid or gas for inflating the ring 20 is supplied by a pump 25 through a control valve 31. The inflation pressure in pipe 24 acts on the valve 31 in opposition to the force exerted by a spring 30, the spring force being adjustable by means of a hand wheel 32. If the inflation pressure differs from the value determined by the setting of the hand wheel 32, the resultant displacement of the valve 31 connects the pipe 24 either to the pump discharge pipe 28 or to a drain pipe 36 whereby the inflation pressure is brought to that value. The manual control of the valve 31 may be replaced by an automatic control dependent on the compressor delivery. Fig. 2 shows a compressor in which the throttling is done by overlapping segments 7a, 7b which are constrained to move radially by the engagement of slots 9 with guides 10, the radial movement being effected by the engagement of pins 12 in cam slots 13 in a disc 11 which is rotated manually by a worm drive 14. The throttling device may be in the form of an iris diaphragm.