ADJUSTABLE VI TYPE INVERTER SCREW COMPRESSOR

PROBLEM TO BE SOLVED: To always enable the maximum efficiency operation corresponding to a load. SOLUTION: Adjustment of ability corresponding to a load is performed by control of the number of revolution of a motor 11 by an inverter 15. When adjusting ability, performing the unload control is dispensed with to restrict deterioration of the operation efficiency. Furthermore, a capacity control valve for controlling capacity is eliminated to simplify a valve control mechanism. In order to obtain the maximum compressor efficiency corresponding to the operating condition (ability) in the variable VI, when a low VI is commanded, a compression part controller 27 moves a slide valve 19 toward a motor 11 side in the axial direction to quicken the compression process completing time, and quickly discharges the compression gas. When a high VI is commanded, the slide valve 19 is moved toward a piston 25 side in the axial direction to delay the compression process completing time, and slowly discharges the compression gas. COPYRIGHT: (C)2004,JPO