SCREW COMPRESSOR AND CONTROL DEVICE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a screw compressor which includes an on/off control valve and is prevented from operating under unnecessarily high pressure.

SOLUTION: The screw compressor 1 has an on/off control valve on the suction side thereof, and a pressure detection means 3 on the discharge side thereof. A detection means 30 for detecting a cycle time in full-load operation and no-load operation is arranged in a control device 2. The on/off control valve is turned on and the screw compressor operates under full-load operation when the discharge pressure reaches a lower limit pressure set value. The on/off control valve is turned off and the screw compressor operates under no-load operation when the discharge pressure reaches an upper limit pressure set value. The flow rate to be consumed in one cycle time including both full-load operation and no-load operation is calculated by using the full-load operation time and no-load operation time detected by the detection means. The lower limit pressure set value and the upper limit pressure set value are adjusted automatically to keep the terminal pressure constant. A display 25 for displaying the operating condition and operating state of the screw compressor is arranged in the control device.

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