SCREW COMPRESSOR

摘要

PURPOSE:To obtain a sufficient delivery capacity decreasing effect by the small moving amount of an unload valve by a method wherein an unload hole is formed on a rotor casing at a part surrounding a compression chamber while an unload valve is fitted into the hole slidably. CONSTITUTION:The unload hole 60 is opened at the inner surface of the rotor casing main body 10 so as to be communicated with the compression chamber under the initial period of compression stroke while it is also communicated with a suction chamber 40 through an unload path 62, penetrating through the rotor casing main body 10 and a front side plate 12 and arriving at a space inside of a front housing 52. The unload valve 64 is fitted into the unload hole air- tightly and slidably substantially while the unload valve 64 is advanced against the energizing force of a spring 70 when a high pressure fluid is supplied to a pressure chamber 72, and the delivery capacity decreasing effect may be obtained.