The hollow-core design of the IOS (Inside Out Stepper) motor reverses the conventional stator and rotor positions. Result: a large-through-hole configuration. The laminated stator assembly fits onto a non-rotating pedestal surrounded by a rotatable shaft cup assembly with an open shaft face.

The stationary through-hole accommodates a wide range of optical, electrical, pneumatic, hydraulic, and mechanical components without the potential of chaffing. A simple but effective way to increase motor torque performance without expensive internal changes is to lengthen the IOS motor by stacking motors together.

The size 17-rotor assembly is composed of a permanent-magnet ring surrounded by two soft-iron cups. These cups are laminated and comprised of 50 small vernier teeth. The second rotor cup assembly is constructed similarly, but with a one-half tooth pitch orientation to maximize rotor torque. The miniature size 17 IOS rotor uses a rare earth (Samarium-Cobalt) magnet while the larger size 23 and 34 rotors use alnico.

Allen Bennett, IMS Motors Div., 105 Copperwood Way, Ste. H, Oceanside, CA 92054; Tel: (760) 966-3162; Fax: (760) 966-3165; E-mail: [email protected].

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