OILLESS SCREW COMPRESSOR AND ITS OPERATION METHOD

摘要

PROBLEM TO BE SOLVED: To reduce power at a low load and a low rotational speed in an oilless screw compressor in which an inverter is used. SOLUTION: This oilless screw compressor in which the driving rotational speed of an electric motor 2 is controlled by the inverter comprises a vent pipe 22 branched to the primary side of a check valve 13 in a body discharge pipe 21 and opening to the atmosphere at one end. A vent bypass pipe 22A having a small-diameter two-way solenoid valve 27 bypassing the large-diameter two-way solenoid valve 26 is installed in the vent pipe 22. The compressor comprises a pressure detector 24 detecting the pressure of the compressed air in a delivery pipe 15 on the downstream side of a check valve 13 and a controller 17 controlling the opening and closing of the large-diameter two-way solenoid valve 26 and the small-diameter two-way solenoid valve 27 based on the output of the pressure detector and the rotational speed of the electric motor 2. The drive shaft of an oil pump 28 installed in the compressor body to lubricate bearings is coupled to the shaft end of a speed increasing gear 5 driven by the electric motor 2 through the oil pump gear 29. COPYRIGHT: (C)2007,JPO&INPIT