| 摘要 |
The present invention relates to a variable capacity helical screw compressor for compressing a gaseous medium, usually air. The compressor includes at least one lift valve (1) which connects with a first compression chamber in the compressor. The lift valve (1) includes a valve housing (2), a valve head (6) which can move reciprocatingly in the valve housing (2), a valve stem (5) whose one end is connected to the valve head (6) and whose other end projects out of the housing (2), a valve body (7) that has a valve area (21) at the other end of the valve stem (5), said valve area (21) facing towards the first compression chamber, and a first passageway (28) whose opening (17) opens into the valve housing (2) adjacent a first side of the valve head (6) and whose other end is in selecive fluid contact with either a compressor outlet passageway or with a compressor inlet passageway, a second passageway (19) which connects the valve housing (2) in or adjacent to a second, opposite side of the valve head (6) with a second compression chamber. The compressor includes an elastic device (12) disposed between the other side of the valve head (6) and the valve housing (2), and the first and the second compression chambers are one and the same compression chamber.
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