| 摘要 |
PURPOSE:To aim at energy saving in making unload starting pressure approximate to full-load starting pressure as well as to make a consumption side pressure fluctuation range reducible by performing volume control on the basis of repeating time of unload and full load. CONSTITUTION:When a start switch is turned to ON, an arithmetic processing circuit 22 sets unload starting pressure to an upper limit value of an allowable variable range determined out of rated pressure in a compressor 1, and according to this value, repeating mean time of unload and full load is operated by consumption side pressure being detected by a pressure sensor 19. Then, this repeating mean time is compared with the specified time, and when this repeating mean time is longer, the unload starting pressure is lowered, but when it is shorter, the unload starting pressure is made to go up the other way. With this constitution, since the unload starting pressure is approximated to full-load starting pressure as near as possible, any waste power loss is eliminated, thus energy saving is well promoted. In addition, pressure fluctuations at the consumption side becomes lessened as small as possible. |
