Rotary drive with linear actuators having two degrees of linear movements
A rotary and linear motion device includes a magnetic stator assembly, opposed electromagnetic actuators, and a linear-to-rotary converter (e.g., cam). Each electromagnetic actuator includes a coil that is configured to reciprocate relative to the magnetic stator assembly or to linearly translate in a common direction relative to the magnetic stator assembly. The electromagnetic actuators are coupled to the linear-to-rotary converter and upon reciprocation or linear translation, drive the linear-to-rotary converter in rotary or linear motion. The device may be located inside a wheel, which may be part of a vehicle. If part of a wheel of a vehicle, the device can be used to provide propulsion, steering, braking, and suspension for the vehicle.
1. A rotary drive comprising:
a rotatable member that defines a rotational axis;
a first linear actuator comprising a first mounted member having a first linear axis that is oriented radially relative to the rotational axis and a first moving member that moves in a linear direction along the first linear axis and relative to the first mounted member when a drive signal is applied to the first linear actuator;
a second linear actuator comprising a second mounted member having a second linear axis that is oriented radially relative to the rotational axis and a second moving member that moves in a linear direction along the second linear axis and relative to the second mounted member of the second linear actuator when a drive signal is applied to the second linear actuator;
a mounting structure with the first and second mounted members of the first and second linear actuators mounted thereon;
a converter assembly to which the rotatable member and the moving members of the first and second linear actuators are coupled and which is configured to
(a) convert first type of linear movement of the moving members of both of the first and second linear actuators to rotary movement of the rotatable member about the rotational axis while the rotational axis remains in a fixed relationship to the mounting structure; and
(b) respond to a second type of linear movement of the moving members of both of the first and second linear actuators by causing relative movement between the rotational axis and the mounting structure in a direction that is orthogonal to the rotational axis and without producing rotary movement of the rotatable member.
2. The rotary drive of clam 1 , wherein the mounted member of the first linear actuator comprises a first magnetic stator, said first magnetic stator including one or more magnets generating magnetic fields and the moving member of the first linear actuator comprises a first coil circumscribing the first magnetic stator and arranged to reciprocate within the magnetic fields generated by the first magnetic stator, and
wherein the mounted member of the second linear actuator comprises a second magnetic stator, said second magnetic stator including one or more magnets generating magnetic fields and the moving member of the second linear actuator comprises a second coil circumscribing the second magnetic stator and arranged to reciprocate within the magnetic fields generated by the second magnetic stator.
3. The rotary drive of claim 2 wherein the converter assembly comprises a linear-to-rotary converter coupled between the first and second moving members and the rotatable member.
4. The rotary drive of claim 2 , wherein the converter assembly comprises:
(a) a linear-to-rotary converter to which the rotatable member and the moving members of the first and second linear actuators are coupled and which during operation converts the first type of movement of the moving members of the first and second linear actuators to rotary movement of the rotatable member about the rotational axis; and
(b) a bearing assembly supporting the rotatable member and enabling the rotatable member in response to the second type of movement of the moving members of the first and second linear actuators to move relative to the mounting structure and in the direction that is orthogonal to the rotational axis.
5. The rotary drive of claim 4 , wherein the bearing assembly comprises a bearing support on which the rotatable member is mounted for rotation and a plurality of shafts that enable relative movement between the bearing support and the mounting structure in the direction orthogonal to the rotational axis in response to the second type of movement of the moving members of the first and second linear actuators.
6. The rotary drive of claim 4 , wherein the bearing assembly comprises a plurality of shafts and a plurality of linear bearings movably supporting the moving members of the first and second linear actuators on the plurality of shafts.
7. The rotary drive of claim 2 , further comprising a wheel rim for supporting a tire, said wheel rim mounted on the rotatable member.
8. The rotary drive of claim 7 , wherein the first and second linear actuators, the converter assembly, and the support structure are located within the boundaries of the wheel rim.
9. The rotary drive of claim 2 , wherein the first coil circumscribes at least some of the one or more magnets of the first magnetic stator.
10. The rotary drive of claim 2 , wherein the second coil circumscribes at least some of the one or more magnets of the second magnetic stator.
11. The rotary drive of claim 2 , wherein the first coil and the second coil are opposed to each other relative to the rotational axis.
12. The rotary drive of claim 2 , wherein the first and second axes are parallel to each other.
13. The rotary drive of claim 2 , wherein the first and second axes are collinear.
14. The rotary drive of claim 2 , wherein the converter assembly comprises a cam.
15. The rotary drive of claim 14 , wherein the converter assembly further comprises first and second linkages coupling the first and second coils, respectively, to the cam.
16. The rotary drive of claim 15 , wherein the first and second linkages comprise cam followers which engage with the cam.
17. The rotary drive of claim 2 , wherein the first type of linear movement of the moving members of both of the first and second linear actuators involves the first and second coils moving in opposite directions to each other.
18. The rotary drive of claim 2 , wherein the second type of linear movement of the moving members of both of the first and second linear actuators involves the first and second coils moving in a common direction.
19. The rotary drive of claim 2 , further comprising liquid injection ports arranged to flow coolant onto the first and second coils as the coils reciprocate within the magnetic fields during operation.
20. The rotary drive of claim 19 , wherein the liquid injection ports are arranged in the first and second magnetic stators.
21. The rotary drive of claim 20 , wherein and liquid injection ports are openings in the magnets of the first and second magnetic stators.
22. The rotary drive of claim 2 , further comprising a rotary bearing with the rotatable member rotatably supported on the support structure by the rotary bearing.