STRUCTURE FOR DYNAMIC-PRESSURE BEARING

摘要

PROBLEM TO BE SOLVED: To provide a structure for a dynamic-pressure bearing capable of preventing an oil spill that occurs in the rotation of a shaft body of a dynamic- pressure bearing for use in a small-sized motor represented by an HDD(hard disc drive). SOLUTION: A centrifugal force F1 acts when the shaft body 3 rotates, but a pushback force F2 downwardly moving in parallel along the spiral groove 4c acts on an oil 6 to draw back the oil 6 in an opening side since a spiral groove 4c is formed at a through hole 4b of an upper plate 4. The shaft body 3 and the upper plate 4 are assembled in advance by coinciding the direction of rotation of the shaft body 3 with the direction of rotation at the time of the moving direction along the spiral groove 4c to direct to the inside of the through hole 4b.