| 摘要 |
In a rotary screw compressor with capacity regulating means (14) the axial gas forces on the rotors (12) are balanced by hydraulic thrust balancing means (18). When the compressor is working at reduced capacity below a certain level the thrust balancing force is inactivated. This is accomplished in that the pressure oil supplied to the thrust balancing means (18) is drained by opening a cut-off valve (28) controlling a drainage channel (26) connected to the oil supply channel (24). According to the invention the cut-off valve (28) is directly governed by the capacity regulating means (14) so that when these means are in a position representing a capacity below a certain level, typically about 75 % of full capacity, the drainage channel (26) is connected to a low pressure source. The capacity regulating means can preferably act as the cut-off valve which in the open position connects the drainage channel (26) to the low pressure port (44) of the compressor through the compressor working space (13). |
