System and method for providing rotation control in a limited rotation motor system
View Patent ↗A limited rotation motor system is disclosed that includes a rotor shaft mounted within first and second bearing units. The rotor shaft is coupled to a helically shaped torsion member that is fixed with respect to a motor housing.
1. A limited rotation motor system for driving a rotor shaft in clockwise and counter-clockwise directions responsive to an applied electrical signal, wherein said rotor shaft is mounted within first and second bearing units and is coupled to a torsion member one end of which is fixed with respect to a motor housing, said torsion member being wound in helical form around an extension of an axis of rotation of the rotor shaft, said rotor being centered in its power-off rotational range by means of the torsion member, such rotational range being nominally equal in both the clockwise and the counterclockwise directions, said torsion member also providing that a pre-loading force on each of the first and second bearing units may be independently adjusted.
2. The limited rotation motor system as claimed in claim 1 , wherein said system further includes a helically shaped pre-loading member for applying a pre-loading force to an outer ring of said first bearing unit.
3. The limited rotation motor system as claimed in claim 2 , wherein said helically shaped torsion member is positioned radially within said helically shaped pre-loading member.
4. The limited rotation motor system as claimed in claim 2 , wherein an inner ring of said first bearing unit applies a pre-loading force to an inner ring of said second bearing unit.
5. The limited rotation motor system as claimed in claim 4 , wherein the pre-loading force on said first bearing unit is substantially equal to the pre-loading force on said second bearing unit.
6. The limited rotation motor system as claimed in claim 4 , wherein the pre-loading force on said first bearing unit is greater than the pre-loading force on said second bearing unit.
7. The limited rotation motor system as claimed in claim 4 , wherein the pre-loading force on said first bearing unit is less than the pre-loading force on said second bearing unit.
8. A limited rotation motor system comprising a rotor shaft mounted within first and second bearing units, a pre-loading member for pre-loading an outer ring of said first bearing unit, and a torsion member fixed with respect to a motor housing, said pre-loading member and said torsion member providing that a pre-loading force on the first bearing unit may be adjusted, independent of the resistive torque provided by the torsion member, to be different than a pre-loading force on the second bearing unit.
9. The limited rotation motor system as claimed in claim 8 , wherein said torsion member is coupled to a rotor shaft.
10. The limited rotation motor system as claimed in claim 8 , wherein said pre-loading member and said torsion member are mutually co-axially positioned.
11. The limited rotation motor system as claimed in claim 8 , wherein an inner ring of said first bearing unit applies the pre-loading force to an inner ring of said second bearing unit.
12. The limited rotation motor system as claimed in claim 11 , wherein the pre-loading force on said first bearing unit is substantially equal to the pre-loading force on said second bearing unit.
13. The limited rotation motor system as claimed in claim 11 , wherein the pre-loading force on said first bearing unit is greater than the pre-loading force on said second bearing unit.
14. The limited rotation motor system as claimed in claim 11 , wherein the pre-loading force on said first bearing unit is less than the pre-loading force on said second bearing unit.
15. The limited rotation motor system as claimed in claim 11 , wherein said first bearing unit is slidably mounted to said motor housing and said second bearing unit is fixed to said motor housing.
16. A limited rotation motor system comprising:
a helically shaped torsion member for providing resistive torque to a rotor shaft; and
pre-loading means for pre-loading a first bearing unit and a second bearing unit responsive, in part, to the helically shaped torsion member;
wherein a pre-loading force on said first bearing unit may be adjusted relative to a pre-loading force on said second bearing unit without attendant changes to the resistive torque provided by the torsion member.
17. The limited rotation motor system as claimed in claim 16 , wherein the pre-loading force on said first bearing unit is substantially equal to the pre-loading force on said second bearing unit.
18. The limited rotation motor system as claimed in claim 16 , wherein the pre-loading force on said first bearing unit is greater than the pre-loading force on said second bearing unit.
19. The limited rotation motor system as claimed in claim 16 , wherein the pre-loading force on said first bearing unit is less than the pre-loading force on said second bearing unit.
20. The limited rotation motor system as claimed in claim 16 , wherein said limited rotation motor system is employed in at least one of a raster scanning system and a wafer processing system.
21. The limited rotation motor system as claimed in claim 16 , wherein the resistive torque provided by the torque means remains substantially constant at different system operating temperatures.