Zero air gap orbiting gear stepper motor
AssigneeFord Motor Company
InventorJames E. Marshall
Life of this patent
Estimating the term…
Abstract
A stepper motor having an internally toothed ring gear acting as a stator which is contacted by one or more pinion gears supported by a carrier. The ring gear stator is made up of several sets of teeth which are separately magnetically polarized to move the pinion gears about the ring gear. Three toroidal coils are preferably provided to charge three different sets of teeth which are arranged in a repeating series of three about the ring gear. Alternatively, a linear actuator can be provided to provide a linear output. The teeth may also include an individual coil wherein sets of teeth can be electromagnetically biased into a north or south polarity or remain neutral.
Claims8
A stepper motor comprising:
- a stator gear having a plurality of low reluctance, ferromagnetic, non-permanent magnetic teeth forming sets of pole pieces arrayed in an alternating pattern;
- means for inducing magnetic flux independently in each of said sets of pole pieces;
- a plurality of radially extending insulative spacers disposed between adjacent pole pieces for reducing flux leakage between adjacent pole pieces;
- a rotor including at least one pinion gear having gear teeth which engage the teeth of the stator gear;
- and
- means for controlling opposed electromagnetic charges supplied to said sets of pole pieces forming teeth of the stator gear, said control means sequentially alternating the polarity of the electromagnetic charge supplied to said sets of pole pieces in a desired direction to cause the rotor to move in said direction and holding the rotor in place by fixing the polarity of electromagnetic charge supplied to said sets of pole pieces.
Dependencies are inferred from the claim text.