| 摘要 |
PROBLEM TO BE SOLVED: To provide a scroll compressor whose type of working can be changed over between the internal high pressure type and internal low pressure type, whereby the sealing performance of its back pressure chamber is enhanced in the internal low pressure type operation. SOLUTION: A motor 6 and a compression part 7 are arranged on the left and the right inside a hermetically sealed vessel 1a, the compression part 7 having a revolving scroll 3, and a main frame 4 is formed on the back surface of the revolving scroll 3 to divide the back surface by concentrical circles into three portions, and an inner back pressure chamber 18, central back pressure chamber 19, and outer back pressure chamber 20 are formed by a ring-shaped small seal 16 and large seal 17 to be fitted in ring grooves 4b and 4c formed in the main frame 4, wherein the chambers 18, 19, 20 are put in a low, a middle or high, and a high pressure when the operating mode is in the internal high pressure, while they 18, 19, 20 are put in a low, a middle or high, and a low pressure when the mode is in the internal low pressure. To introduce the high pressure, a communication path 4e to put the discharge chamber 8 in communication with a high pressure introduction passage 4d is formed in the center of the bottom of the ring groove 4b.
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