To improve the long-term durability of a rolling bearing, to perform stable control by a controller of simple constitution, to obtain stable high speed rotation while keeping an appropriate clearance between respective impellers and to prevent the damage of the compressor impeller and the turbine impeller caused by the thermal expansion of a main shaft and the thermal expansion difference between the main shaft and a housing.
An electromagnet 17 of a magnetic bearing is mounted to the housing 14 to face a thrust plate 13a in a non-contact manner, and the impellers 6a, 7a are fitted to the main shaft 13 in common with the thrust plate 13a to drive the compressor side impeller 6a by power generated at the turbine side impeller 7a. The rigidity value of a composite spring formed of rolling bearings 15, 16 and a support system of the rolling bearings is set in the relation to be larger than the negative rigidity value of the electromagnet 17. Cylindrical bearing presser members 43, 45 having flange parts 43a, 45a are arranged between the compressor impeller 6a and the compressor side rolling bearing 15 and between the turbine impeller 7a and the turbine side rolling bearing 16. Further, ring-like members 44, 46 interfering with the flange parts 43a, 45a to regulate the axial movement of the main shaft 13 are arranged at the compressor side casing 6b or the turbine side casing 7b.
SUZUKI NOBUYUKI
YAMADA HIROYUKI
SUZUKI KENICHI
Shuji Sugimoto