Low-profile rotary motor with fixed back iron
View Patent ↗A rotary actuator motor is provided including a stationary coil section and a rotating magnet. The magnet is incorporated with the pivot bearing assembly, and the coil section is aligned with the magnet along an axis of rotation of the actuator. The magnet fully encircles the axis of rotation. The coil comprises one or more closed loops of electrically conductive material. The motor in this arrangement maintains a much smaller profile in comparison to a traditional voice coil motor that is mounted to a yoke extending away from the axis of rotation of the actuator.
1. An apparatus comprising:
a bearing having an inner race and an outer race, said outer race being rotatable about said inner race;
a sleeve mounted over said outer race;
a rotatable asymmetric upper back iron mounted over the sleeve, the upper back iron having an arcuate extension that balances an actuator motor;
a magnet contactingly secured to the rotatable upper back iron and symmetrically secured about the sleeve;
a lower fixed back iron mounted adjacent said bearing so that the bearing protrudes through an aperture in the fixed back iron;
a coil secured to said lower back iron, said coil being longitudinally aligned with said magnet; and wherein
a selected voltage and amperage applied to said coil causes rotation of said magnet with respect to said coil, and in turn results in said rotation of said outer race about said inner race.
2. The apparatus of claim 1 , wherein the asymmetric upper back iron conducts magnetic flux as a magnetic return path and accommodates a predetermined moment about a pivot bearing.
3. The apparatus of claim 1 , wherein said coil comprises at least one closed loop of electrically conductive material arranged about an axis of rotation.
4. The apparatus of claim 1 , wherein the arcuate extension protrudes less than a circumferential distance about the upper back iron.
5. The apparatus of claim 1 , wherein said magnet is disposed directly above and spaced from said coil, said magnet and said coil being aligned with respect to a central axis extending through said magnet and said coil.
6. The apparatus of claim 1 , wherein said lower back iron and said upper back iron are each substantially planar and each extend orthogonal with respect to a central axis of said motor.