Importance

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Abstract

A simplified fan and brushless DC motor employs an annular permanent magnet magnetized in segments about its circumference. Each segment is oppositely radially magnetized with respect to the preceding segment as one proceeds around the magnet. Fan blades are located within the annular magnet. A coil and electromagnet structure defining two pole pieces reside outside the permanent magnet annulus. A Hall effect device switches the coil off and on in response to passage of the segments of the rotor magnet. Thus commutated, the single coil affects rotation of the rotor and the fan blades. A permanent magnet supported on the stator structure serves to magnetically detent the permanent magnet of the rotor, bringing the rotor to rest correctly for restarting.

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First Claim