To reduce the vibration of a fan associated with an increase of a wind volume caused by the high-speed rotation of the cooling fan.
The fan includes a motor and an impeller, the static part of the motor is composed of a stator 32 and a bearing 44, the bearing comprises a sleeve 47 being a metal sintered compact and a cylindrical bearing housing 48, and a rotating part has a rotor magnet, a shaft 41 inserted into the sleeve and a thrust plate 42 which expands to the radial direction from the lower end of the shaft. A radial dynamic-pressure bearing for generating the fluid dynamic pressure of lubricating oil flowing to the lower part in the axial direction is constituted in a radial gap between the inner peripheral surface of the sleeve and the outer peripheral surface of the shaft, a thrust dynamic-pressure bearing for generating the fluid dynamic pressure of lubricating oil flowing to the inside in the radial direction is constituted in a thrust gap between the lower surface of the sleeve and the upper surface of the thrust plate, a circulation hole 445 extending in the axial direction is located between the sleeve and the bearing housing, and the width in the radial direction of the radial gap is ≥5 μm and ≤20 μm.
HASEGAWA TOMOHIRO
NODA SHINICHIRO
IKEGAMI SHOJI
FUJIMOTO MASAFUMI
Tsutomu Tanaka
Masamichi Ida
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