Valve installation method; valve construction;and control system

摘要

A lift valve is installed to a compression chamber of a screw compressor, the valve shaft is fully extended and maintained at full extension, and the upper surface of the valve element and the inner surface of the compression chamber are simultaneously machined so that the valve surface becomes a continuation of the inner wall of the chamber. The valve is actuated by a piston 411 reciprocating within the housing and including two pressure passages 425, 427 which are in fluidic communication with the inlet and outlet pressures of the compressor. A plurality of such lift valves are used to control the capacity of the compressor.