US Patent 8157543 High-speed rotating shaft of supercharger

In a high-speed rotating shaft (10) of a supercharger which is rotatably supported by two radial bearings (12a, 12b) spaced at a fixed distance (L), directly couples a turbine impeller fixed to one end and a compressor impeller fixed to the other end, and transmits a rotational driving force of the turbine impeller to the compressor impeller, a small shaft portion (14) having a smaller diameter than a bearing portion is provided between bearings. The small shaft portion (14) is offset to a compressor side.