ポケット付きオリフィス絞りを有する静圧気体ジャーナル軸受の減衰特性

抄録

Recently, gas bearings have been used in high technology industry. By the use of pocketed orifice restrictors, the stiffness of the bearings is greater than that of inherently compensated bearings and the highest value is obtained at 10 μm (0.1 mm in orifice diameter) in mean radial clearance. But in these bearings, the pocket volume exists in the bearing surface, therefore it is possible that damping coefficients get to minus sign. In this paper, damping coefficients are measured when a sinusoidal force and an impact force act to the shaft, and theoretical calculations and experimental results are compared. Following conclusions are obtained : (1) Damping coefficients are affected by the pocket depth, eccentricity ratio and orifice diameter, but this bearing system is always stable under the condition that nondimensional pocket depth N is less than 3-8. (2) When the sinusoidal vibration is given, stiffness and damping coefficients are beginning to vary in σ> 0.5.