Piston unloader arrangement for screw compressors

摘要

A screw compressor employs a piston unloader disposed in a bore remote from the compressor's working chamber. Flow communication between the bore and working chamber is through a series of unloader ports. The unloader piston has an end portion of uniform geometry which causes the physically non-overlapping unloader ports to, in effect, overlap in operation and is such that the unloader piston need not be maintained in any specific orientation within the bore in which it resides in order to unload the compressor in a continuous fashion.