| 摘要 |
<p>A screw compressor is connected to a motor to be driven by the motor even during periods of low compressed air consumption. During such periods, the screw compressor is at least partially unloaded to make it easier and less costly to drive the compressor. The unloading is performed by removing air from the compressor. Preferably, that is done by communicating the air inlet of a small capacity vacuum device with the air outlet of the screw compressor. Suction from the vacuum device is transmitted to the air outlet of the screw compressor to suck air out of the screw compressor to reduce the engine horsepower needed to rotate the screw compressor. The vacuum device can also be used to boost the air volume and/or the air pressure. The system can be used in a drilling rig which drills holes in the ground. The screw compressor can be unloaded during start up of the motor by briefly driving the vacuum device by pressurized liquid from a pre-pressurized hydraulic accumulator.</p> |
