| 摘要 |
PROBLEM TO BE SOLVED: To improve durability of a motor by improving lubrication characteristics between the inside diameter face of a bearing, and a shaft. SOLUTION: Cut portions are formed on an outer peripheral face of portions of the shaft which come into contact with at least the inner diametrical face of the bearing, wherein the cut portions are formed as such as flat faces or groove types with cross-sectional shapes which form acute angles between the shaft and the inside diameter face of the bearing. With such a constitution, a contact area with the inside diameter face of the bearing is not only reduced, but also lubricating oil oozing from the sintered bearing, when the motor rotates is collected at oil pockets (cut portions) formed between the inside diameter face of the bearing and the outer peripheral face of the shaft; then when the shaft rotates, the oil forms a strong oil film near the cut portions of the cross-sectional shapes forming the acute angle between the inside diameter face of the bearing and the shaft, by which the rotary deflection of the shaft is suppressed, and frictional resistance, caused by the shaft and the bearing at high-speed rotation, is sharply decreased to reduce heat generation. COPYRIGHT: (C)2007,JPO&INPIT
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