High-speed rotation of various rotors such as motors for electric vehicles causes a problem that a windage loss increases significantly. Our group has proposed a self-evacuating pump with spiral grooves as a windage-loss-reduction method. It is important to maintain the gap between the rotor and the outer wall quite narrow such as 10 μm. In this study, an "Omusubi-shaped" floating bush is proposed to keep the gap narrow even under the condition that the rotor vibrated and thermally expanded. We examined the required gap value between bush and rotor which is necessary for a high-performance depressurization function. In order to demonstrate the feasibility of this method, we evaluated the levitation ability of the "Omusubi-shaped" floating bush.
