Fluid dynamic bearing with low stiffness change over temperature

Abstract

A fluid dynamic bearing is described having an inner element made of a first material with a first coefficient of thermal expansion, an outer element made of a second material with a second coefficient, and a layer of viscous fluid in contact with and separating the inner element from the outer element such that said outer element is capable of rotation around said inner element. By choosing particular materials, the difference between the first and second coefficients of thermal expansion can be controlled, and the thickness of the layer of viscous fluid can be made to vary with temperature. This allows for some degree of control over the temperature dependence of the stiffness and drag of the fluid dynamic bearing. In particular, the coefficients of thermal expansion can be chosen so as to cancel out any temperature dependence of stiffness and/or drag due to a temperature dependence of the viscosity of the viscous fluid.

Dependencies are inferred from the claim text.