Electromechanical limited rotation rotary actuator and method employing segmented coils
An electromechanical rotary actuator includes a stator having teeth extending inwardly from an inner wall surface, wherein free ends of each tooth form an aperture dimensioned for receiving a rotor, the free ends forming a gap therebetween. A segmented set of electrical coils extends around each tooth, wherein each coil of the segmented set has a thickness sufficient for passing through the gap between the first and second teeth. Electrically insulating tabs extend into an opening around each tooth carrying the segmented set of coils. The tabs maintain each of the coils within the segmented set in a spaced relation to the stator. When fabricating the actuator, each of the coils are fabricated and individually placed around a tooth with each coil having a thickness and breadth for optimally packing the stator.
1. A limited rotation rotary actuator comprising:
a stator having first and second teeth extending inwardly from an inner wall surface thereof, wherein a free end of each tooth in combination forms an aperture dimensioned for receiving a rotor therein, and wherein the free end of the first tooth is in spaced relation to the free end of the second tooth to form a gap therebetween; and
a first segmented set of electrical coils extending around the first tooth; and
a second segmented set of electrical coils extending around the second tooth,
wherein each coil of the first and second segmented sets of electrical coils has a thickness sufficient for passing through the gap between the first and second teeth.
2. The actuator according to claim 1 , further comprising electrically insulating tabs extending into an opening around each tooth.
3. The actuator according to claim 2 , wherein the tabs extend from a retainer carried by the teeth.
4. The actuator according to claim 3 , wherein the retainer comprises a disk having a cross section generally following a cross sectional shape of the stator while providing an overlap along edges thereof.
5. The actuator according to claim 4 , wherein the retainer comprises third and fourth teeth extending inwardly from an inner wall surface thereof, wherein free ends of each of the third and fourth teeth form an aperture dimensioned for receiving the rotor therein, wherein the free end of the third tooth is in spaced relation to the free end of the fourth tooth to form a separation therebetween, and wherein the separation is sufficient for receiving the coil thickness therethrough.
6. The actuator according to claim 5 , wherein free ends of each of the third and fourth teeth comprise a protrusion protruding therefrom for maintaining the first and second segmented sets of electrical coils within a desired coil area of the stator.
7. The actuator according to claim 1 , wherein each of the first and second segmented sets of electrical coils comprise at least two coils, and wherein each of the two coils was formed outside the stator.
8. The actuator according to claim 1 , wherein the stator comprises a cylindrical shape, and wherein the first and second teeth extend radially inward.
9. The actuator according to claim 1 , wherein end portions of the teeth together form the aperture having at least one of a circular and oval cross section.
10. The actuator according to claim 1 , wherein the stator comprises multiple laminations, and wherein at least one lamination includes an electrically insulating tab.
11. The actuator according to claim 1 , further comprising a rotor extending into the aperture and a magnet carried by the rotor, wherein the aperture comprises an oval cross-section for receiving the magnet therein, and wherein a separation between the free ends of the teeth and the magnet varies about a periphery of the magnet.
12. The actuator according to claim 1 , further comprising a rotor extending into the aperture and a magnet carried by the rotor, wherein the aperture comprises a circular cross-section for receiving the magnet therein, and wherein a separation between the free ends of the teeth and the magnet is constant about a periphery of the magnet.
13. A limited rotation rotary actuator comprising:
a stator having first and second teeth extending inwardly from an inner wall surface thereof, wherein a free end of each tooth in combination forms an aperture dimensioned for receiving a rotor therein, and wherein the free end of the first tooth is in spaced relation to the free end of the second tooth to form a gap therebetween; and
a segmented set of electrical coils extending around the first tooth,
wherein each coil of the segmented set of electrical coils has a thickness sufficient for passing through the gap between the first and second teeth.
14. A method of fabricating a limited rotation rotary actuator, the method comprising:
providing a stator having first and second teeth extending inwardly from an inner wall surface thereof, wherein a free end of each tooth forms an aperture dimensioned for receiving a rotor therein, and wherein the free end the first tooth is in spaced relation to the free end of the second tooth for forming a gap therebetween;
forming a first coil having an opening therein for extending around the first tooth, wherein the coil has a thickness sufficient for passing through the gap;
passing the first coil through the gap and positioning the first coil around the first tooth;
forming a second coil having an opening therein for extending around the first tooth, wherein the second coil has a thickness sufficient for passing through the gap;
passing the second coil through the gap and positioning the second coil around the first tooth;
forming a third coil having an opening therein for extending around the second tooth, wherein the coil has a thickness sufficient for passing through the gap;
passing the third coil through the gap and positioning the third coil around the second tooth;
forming a fourth coil having an opening therein for extending around the second tooth, wherein the fourth coil has a thickness sufficient for passing through the gap; and
passing the fourth coil through the gap and positioning the fourth coil around the second tooth.
15. The method according to claim 14 , further comprising repeating the forming and passing steps for providing a segmented set of electrical coils around each tooth.
16. The method according to claim 15 , further comprising extending electrically insulating tabs into an opening around each tooth for maintaining each of the coils within the segmented set in a spaced relation to the stator.
17. The method according to claim 16 , wherein the tabs extending step is completed prior to the coil passing steps.
18. The method according to claim 14 , wherein the stator providing step comprises forming the stator by stacking multiple laminations.
19. The method according to claim 18 , further comprising forming at least one lamination as an electrically insulating layer having the tabs extending into an opening around each tooth for maintaining each coil within the segmented set of coils in a spaced relation to the stator.
20. The method according to claim 14 , further comprising connecting the segmented coils extending around the first tooth in series for providing an equivalent of a single coil wound around the first tooth.
21. The method according to claim 14 , further comprising connecting the segmented coils extending around the second tooth in series for providing an equivalent of a single coil wound around the second tooth.
22. The method according to claim 14 , wherein the stator providing step includes providing at least one tooth having a slot extending longitudinally therethrough.
23. The method according to claim 22 , further comprising placing a restoring magnet in the slot.
24. The method according to claim 14 , wherein the stator providing step comprises providing a free end of each tooth forming an aperture having an oval cross section.