Spindle motor having reduced torque ripple

Details Spindle motor having reduced torque ripple Spindle motor having reduced torque ripple

1991-04-29

1992-03-03

Stephan, Steven L.

Electrical generator or motor structure

Dynamoelectric

Rotary

310 67R, 335302, H02K 2112, H02K 700, H01F 702

Patent

active

050935950

ABSTRACT:
A disc drive includes a stationary frame and vertical spindle shaft, and a hub rotatable relative to the spindle shaft and supporting one or more magnetic discs. A motor for rotating the hub includes an annular stator integrally secured to the spindle shaft, and a rotor assembly integral with the hub. The rotor assembly includes an annular magnet and an annular back iron, with the magnet being spaced apart from the stator to define an air gap. The magnet includes four longitudinally disposed arcuate poles of equal size, separated from one another by flux gaps. Each of the poles has a medial region and first and second end regions on opposite sides of the medial region. The medial region is selectively magnetized to a level less than the level to which the end regions are magnetized, creating a flux gap and torque profile for the magnet particularly effective in reducing torque ripple.

REFERENCES:
patent: 4110718 (1978-08-01), Odor et al.
patent: 4217508 (1980-08-01), Uzuka
patent: 4417167 (1983-11-01), Ishii et al.
patent: 4438362 (1984-03-01), Brown
patent: 4574211 (1986-03-01), Muller et al.
patent: 4698542 (1987-10-01), Muller
patent: 4760298 (1988-07-01), Kitahara et al.
patent: 4814652 (1989-03-01), Wright
patent: 4847712 (1989-07-01), Crapo
patent: 4918346 (1990-04-01), Tajima et al.

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