| 摘要 |
PROBLEM TO BE SOLVED: To provide a scroll compressor changeable between an internal high-pressure type and an internal low-pressure type according to operation conditions, allowing a press of a swirl scroll to a fixed scroll in an optimum state at any time. SOLUTION: In this compressor, the rear face of an end plate of the swirl scroll 9 is partitioned into an annular outer back pressure chamber 20a, a central back pressure chamber 20b and an inner back pressure chamber 20c. Pressing force is applied on the swirl scroll 9 to the fixed scroll 8 by always supplying a low pressure to the outer back pressure chamber 20a, supplying a high pressure to the central back pressure chamber 20b and the inner back pressure chamber 20c in internal high-pressure operation, and supplying a high pressure to the central back pressure chamber 20b in internal low-pressure operation. A size of the central back pressure chamber 20b is set to a size such that a prescribed pressing force allowing a bearing pressure applied to a pressure reception face of the swirl scroll 9 to overcome a separation force by an inner pressure of a compression chamber is obtained in the internal low-pressure operation. On the basis of the size of the central back pressure chamber 20b, a size of the inner back pressure chamber 20c and a size of the outer back pressure chamber 20a are decided.
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