ROTARY UNIT

摘要

A rotary unit (RU) is provided with: a supercharger rotating shaft (44); an impeller (50) attached to the supercharger rotating shaft (44), the impeller (50) pressurizing fluid drawn in from the side of one end (44a) of the supercharger rotating shaft (44); and a fastening member (85) for pushing the impeller (50) in the axial direction of the supercharger rotating shaft (44) to secure the impeller (50) to the supercharger rotating shaft (44). The fastening member (85) has in the interior a female screw part (106) threaded with a male screw part (104) of the supercharger rotating shaft (44), and an outer surface (86b) of a distal end part (85a) of the fastening member (85) is formed into a decreasing-diameter shape that continuously and smoothly tapers the farther the fastening member (85) is from the impeller (50).