Magnetorheological actuators

1. An actuator, comprising:

a motor/generator element comprising:

a stator made of a high magnetic permeable material, an outer coil being wound around the stator;

a rotor made of a high magnetic permeable material and with a plurality permanent magnets fixed thereon; and

a cavity configured to receive a fluid; and

a clutch/brake element arranged in the cavity, an inner coil being wound around the clutch/brake element,

wherein the fluid is capable of producing a shear stress in response to an electromagnetic field induced from the inner coil.

2. The actuator according to claim 1 , wherein the fluid comprises a magnetorheological fluid, an electrorheological fluid or an electromagnetorheological fluid.

3. The actuator according to claim 1 , further comprising:

an isolation layer made of a nonmagnetic material and located between the motor/generator element and the clutch/brake element to insulate a magnetic field of the permanent magnets.

4. The actuator according to claim 1 , further comprising:

a guide layer made of a high magnetic permeable material located between the motor/generator element and the clutch/brake element to guide a magnetic flux caused by the inner coil.

5. The actuator according to claim 1 , wherein the rotor is arranged inside the stator and the cavity is formed inside the rotor, or the rotor surrounds outside the stator and the cavity is formed inside the stator.

6. The actuator according to claim 5 , wherein the clutch/brake element comprises an inner armature made of a high magnetic permeable material around which the inner coil is wound.

7. The actuator according to claim 5 , wherein the clutch/brake element comprises a set of input plates and a set of output plates spaced apart by a plurality of nonmagnetic spacer rings.

8. The actuator according to claim 7 , wherein the clutch/brake element further comprises a core made of a high magnetic material around which the inner coil is wound.

9. The actuator according to claim 7 , wherein the clutch/brake element further comprises a bobbin made of a nonmagnetic material outside of the input plates, and the inner coil is wound around the bobbin.

10. The actuator according to claim 7 , wherein the clutch/brake element comprises two shafts with flanges made of a high magnetic permeable material, and the inner coil comprises a plurality of axial coils sticked on the flanges.

11. The actuator according to claim 1 , wherein the outer coil is implemented by a print circuit.

12. The actuator according to claim 1 , wherein the clutch/brake element has a shaft fixed to a housing of the actuator for receiving the motor/generator element and the clutch/brake element.

13. The actuator according to claim 1 , further comprising:

a sensor configured to sense a change of a magnetic direction of the permanent magnets; and

a controller configured to adjust a voltage applied to the outer coil based on the sensed change so that the rotor is able to rotate continuously.

14. An actuator, comprising:

a motor/generator element comprising:

a stator made of a high magnetic permeable material;

a rotor made of a high magnetic permeable material and with a plurality permanent magnets fixed thereon; and

a side plate around which a set of axial coils are wound, the axial coils being arranged corresponding to the plurality of permanent magnets; and

a clutch/brake element being co-axial with the motor/generator element, an inner coil being wound around the clutch/brake element, the clutch/brake element comprising a cavity for receiving a fluid which is capable of producing a shear stress in response to an electromagnetic field induced from the inner coil.

15. The actuator according to claim 14 , wherein the fluid comprises a magnetorheological fluid, an electrorheological fluid or an electromagnetorheological fluid.

16. The actuator according to claim 14 , further comprising:

an isolation layer made of a nonmagnetic material and located between the motor/generator element and the clutch/brake element to insulate a magnetic field of the permanent magnets.

17. The actuator according to claim 14 , further comprising:

a guide layer made of a high magnetic permeable material located between the motor/generator element and the clutch/brake element to guide a magnetic flux caused by the inner coil.

18. The actuator according to claim 14 , wherein the clutch/brake element comprises an inner armature made of a high magnetic permeable material around which the inner coil is wound.

19. The actuator according to 14 , wherein the clutch/brake element comprises a set of input plates and a set of output plates spaced apart by a plurality of nonmagnetic spacer rings.

20. The actuator according to claim 19 , wherein the clutch/brake element further comprises a core made of a high magnetic material around which the inner coil is wound.

21. The actuator according to claim 19 , wherein the clutch/brake element further comprises a bobbin made of a nonmagnetic material outside of the input plates, and the inner coil is wound around the bobbin.

22. The actuator according to claim 19 , wherein the clutch/brake element comprises two shafts with flanges made of a high magnetic permeable material, and the inner coil comprises a plurality of axial coils sticked on the flanges.

23. The actuator according to claim 14 , wherein the outer coil is implemented by a print circuit.

24. The actuator according to claim 14 , wherein the clutch/brake element comprises a shaft fixed to a housing of the actuator for receiving the motor/generator element and the clutch/brake element.

25. The actuator according to claim 14 , further comprising:

a sensor configured to sense a change of a magnetic direction of the permanent magnets; and

a controller configured to adjust a voltage applied to the outer coil based on the sensed change so that the rotor is able to rotate continuously.