With the dynamical pressure effect of the dynamical pressure channel which was formed to the dynamical pressure

摘要

PROBLEM TO BE SOLVED: To provide a hydrodynamic bearing having long durability and a reduced potential difference between a shaft and a bearing by using a neopentyl glycol mixed ester of caprylic acid and capric acid as the base oil of a lubricating oil for a hydrodynamic bearing.;SOLUTION: This hydrodynamic bearing is provided by using a neopentyl glycol mixed ester of caprylic acid and capric acid as the base oil of a lubricating oil for a kinetic pressure fluid bearing having the following structure. That is, in the kinetic bearing fluid bearing, a rotary shaft is supported in a noncontact manner by means of the kinetic pressure generated in gaps in the bearing due to the kinetic effect attributable to kinetic grooves formed against the thrust and radial directions to the shaft or the bearing surface body. The neopentyl glycol mixed ester of caprylic acid and capric acid is expressed, for example, by the formula [R1 and R2 are each CH3(CH2)n (6≤n≤8)]. The volume resistivity of the lubricating oil is preferably ≤1.0×1011 Ω.cm. The kinetic pressure fluid bearing is used, for example, in a spindle motor or the like in a rotor apparatus of a magnetic disk-driving device or the like.;COPYRIGHT: (C)2000,JPO