| 摘要 |
PROBLEM TO BE SOLVED: To provide a turbo compressor and a turbo refrigerator capable of making small a seal gap between a back surface of each impeller and a casing to reduce gas leakage and improving compression efficiency by using a rotational shaft axial position control mechanism of a thrust magnetic bearing.SOLUTION: In a turbo compressor 1 having a rotational shaft 5 supported by a magnetic bearing, seal portions between a rotational portion on a back surface of each of impellers 3 and 4 and a casing 6 is formed radially between a fixed seal surface of a stationary wall of the casing 6 opposite to the impellers 3, 4 and a rotational seal surface 21 of a rotational member opposite to the fixed seal surface. The turbo compressor 1 includes a control unit 25 for detecting an axial position of each of the impellers 3, 4 or the rotational shaft 5 so as to control the position by using an axial position control mechanism over the rotational shaft 5 by thrust magnetic bearings 9, 10, and switching a gap T in a thrust direction of the seal portion over between a gap during a transient operation corresponding to a bearing gap between the radial magnetic bearings 9 and 10 and a smaller gap during a steady operation. |
