| 摘要 |
PROBLEM TO BE SOLVED: To obtain a power saving effect by limiting compressors performing full load operations according to fluctuating load and compressors performing capacity controls by revolution speed controls to one compressor and stopping other compressors or controlling capacity by full load operations. SOLUTION: Control upper limit pressure H and control lower limit pressure L are set in a control device 12, the control upper limit pressure H and the control lower limit pressure L are always compared with pressure detected by a pressure sensor 7 and the order of compressors performing capacity controls is set. A control device 8 performs a revolution speed control for only a compressor 5 if pressure in an air tank is L or more and H or below during operations of the compressors and operates other compressors with full load without performing the capacity controls. If pressure in the air tank becomes H or more, a stop signal of the compressor 5 is transmitted from the control device 8, and at the same time, the revolution speed control is switched to a compressor 4. Every time consumption is reduced and pressure reaches H by air quantity discharged from the devices 12 and 8, this operation is repeated and the compressors are successively stopped. When pressure becomes L or below, the compressors are started in the reverse order and the capacity controls are performed. |
