DYNAMIC PRESSURE BEARING DEVICE

PROBLEM TO BE SOLVED: To prevent the outflow of a hydraulic fluid, and to easily assemble a bearing by setting clearance between an outside end surface of a thrust bearing member and an inside end surface of a cover member not less than a specific value. SOLUTION: In a bearing of 7.5 mm in an outer diameter of thrust bearing members 131a, 131b, when rotating a bearing device set to 0.15 mm in clearance between the thrust bearing members 131a, 131b and a cover 125 by 14,000 revolution, a hydraulic fluid does not contact with the cover 125. When there is clearance by 0.15 mm or more, even if there is a fluctuation in assembling, since a liquid level does not contact with the cover 125, the clearance is easily controlled at assembling time. The clearance is desirably larger than 0.15 mm, and when the clearance is too large, since the hydraulic fluid leaks as mist, about 0.3 mm become the uppper limit. The outflow of the hydraulic fluid can be prevented without using an expensive magnetic fluid by applying an oil repellent agent between the cover 125 and a thrust plate.