| 摘要 |
PURPOSE:To improve operation efficiency, by driving an internal displacement ratio variable mechanism when a change width of compression ratio increases to a predetermined value or more. CONSTITUTION:A pressure transmitter 22 is provided in a delivery pressure pipe 13 of a screw compressor 11. A delivery pressure signal, detected by the pressure transmitter 22, is input to an arithmetic unit 23, here compression ratio is calculated. The calculated compression ratio changes, and when its change width increased to a predetermined value or more, a four way type solenoid valve 19 is driven to supply pressure oil to and discharge it from a driving oil hydraulic cylinder 17 of an internal displacement ratio variable mechanism, both actuating it and regulating internal displacement ratio of the screw compressor to an optimum value. |
