| 摘要 |
A screw compressor has a housing (22; 302) having first (53; 330) and second (58; 340) ports along a flowpath. A first rotor (26; 306) has a lobed body. A second rotor (28; 308, 310) has a lobed body enmeshed with the first rotor body. The rotors and housing cooperate to define a compression path between suction (60; 332) and discharge (62; 342) locations along the flowpath. Means (100, 110, 120; 200, 210, 220; 370, 380, 390) provide relative longitudinal movement between a blocking portion (57; 352) of the housing and at least one of the first rotor and second rotor between: a first condition wherein a pocket of the first and second rotors is closed by the blocking portion; and a second condition wherein the blocking portion does not close the pocket. To provide capacity control, a control system (110; 390) is configured to provide duty cycle control of the movement.
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