Optimization of the Hollow Shaft in an Air Compressor Rotor for Hydrogen Fuel Cell

Hollow shaft with light weight and small moment of inertia is suitable for the motor rotor due to the demand for high speed and energy conservation. In this paper, the influence of hollow aperture on strength and critical speed was calculated by simulation method. It is concluded that for a three-section type rotor, when the ratio of the inner and outer diameters of the hollow shaft is 0.18–0.55 while the interference between sheath and shaft is 0.06–0.08 mm, difference of the sheath stress, the shaft stress, the pressure between sheath and shaft, the maximum deformation and the critical speed between the hollow shaft rotor and the solid shaft rotor is within 5%. The change rate of rotor strength and critical speed caused by the increase of hollow diameter is much lower than the change rate of rotor mass. Optimal design of the hollow aperture, hole length and interference between sheath and shaft was performed considered the minimum mass, the minimum interference, the restrict of strength and rotor dynamics based on response surface method. The rotor dynamics of the gas foil bearing-rotor system under real conditions was calculated. It was verified by prototype test that the selected hollow shaft structure meets the requirements.