Machine Design

Magnets and bearing keep fans in line, and quiet too

Sunon Inc., Brea, Calif., devised a fan in which the permanent magnet in the motor's rotor assembly interacts with a metal plate to generate a magnetic field.

In traditional fans, a shaft carries the weight of the blades, and the blades tend to wobble during rotation. This wears down the fan's bearing, causing noise, unwanted vibrations, and premature bearing failure, especially when the fan is mounted vertically. To solve this problem, engineers at This field keeps the fan blades in nearly perfect circular orbits around the bearing and shaft, and supports the weight of the blades. All this reduces noise and vibration, while extending the fan's life. It also does away with several parts -- a lockwasher, oil ring, and spacer washers -- which are susceptible to mechanical failure and degradation.

Fan operation and life further improves through use of the company's Vapo-bearing system. Conventional roller bearings generate friction and heat at high-speeds. The heat transforms some of the lubricant into a gas. The gas solidifies into black nitride inside the bearing, decreasing fan performance. The Vapo bearing lets the gas escape and is just as efficient as a ball bearing. It also resists wear and shock better than roller bearings and can be mounted at any angle.

The fan and bearing system come in sizes ranging from 40 3 40 3 10 mm to 60 3 60 3 25 mm, maximum speed and airflow is 8,200 rpm and 23 cfm. They generate about 18 dBA of noise when operating. The fans will initially be used in PCs, but will also be sized for industrial equipment and mainframe computers.

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