Piezoelectric actuator or motor, method therefor and method for fabrication thereof

• US 6,184,609 B1
• Filed: 09/16/1998
• Issued: 02/06/2001
• Est. Priority Date: 03/26/1996
• Status: Expired due to Term

• Current Assignee: Piezomotors Uppsala AB
• Original Assignee: Piezomotors Uppsala AB
• Inventors: Johansson, Stefan, Bexell, Mats
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US09/142,874
• Time in Patent Office: 874 Days
• Field of Search: 310/328, 310/367
• US Class Current: 310/328
• CPC Class Codes: H02N 2/0095 producing combined linear and rotary motion, e.g. multi-direction positioners
• CPC Class Codes: H10N 30/202 using longitudinal or thickness displacement combined with bending, shear or torsion displacement
• CPC Class Codes: H10N 30/501 having a non-rectangular cross-section in a plane parallel to the stacking direction, e.g. polygonal or trapezoidal in side view
• CPC Class Codes: H10N 30/503 having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view
• CPC Class Codes: H10N 30/505 the cross-section being annular

Abstract

This invention relates to an actuator or motor comprising an electromechanical material which alters its shape under the influence of an electrical voltage. Said actuator comprises at least a monolitic module (1,2) with electrodes integrated in said electromechanical material and in that the force or displacement due to the applied voltages is transferred, to the point to be actuated or moved by the shape change of the material, using at least two independent contact points. The invention also relates to a method for fabricating said actuator or motor.

Claims

1. An actuator or motor having electromechanical material which alters its shape under the influence of an electric field, whereby motion relative a body is created by non-resonant repetition of small steps, said actuator or motor comprising at least one monolithic module with electrodes integrated in said electromechanical material, said monolithic module being a sintered block and having at least one passive part and at least two active elements, one independent contact point at each active element being provided against said body, which contact points are positionable independently of each other in at least two independent directions relative to said passive part of said monolithic module, whereby said monolithic module by itself or in combination with others is used for creating said motion.

2. An actuator or motor according to claim 1, wherein said contact points are positionable independently of each other, relative to said passive part of the monolithic module, in three independent directions.

3. An actuator or motor according to claim 1, wherein said contact points of the monolithic modules are located in a plane being inclined relative to a base plane of said monolithic module or an attached unit.

4. An actuator or motor according to claim 1 , wherein said monolithic modules have a spherical contact geometry.

5. An actuator or motor according to claim 3, further including a bellow shaped tube, structured and arranged to create a normal force between said monolithic modules.

6. An actuator or motor according to claim 1, wherein said monolithic modules are pressed against said body.

7. An actuator or motor according to claim 6, wherein said monolithic modules are pressed against said body by gravitational, electrostatic, molecular, atomic or viscous forces.

8. An actuator or motor according to claim 6, wherein said monolithic modules are pressed against said body by magnetic forces.

9. An actuator or motor according to claim 6, wherein said monolithic modules are pressed against said body by elastic spring forces.

10. An actuator or motor according to claim 1, wherein three dimensional cavities are integrated in said monolithic modules.

11. An actuator or motor according to claim 10, wherein at least a part of said active elements is built-up by base units, comprising structures, which are curved in two or in three dimensions.

12. An actuator or motor according to claim 10, wherein at least a part of said active elements is built-up by arch-shaped structures which are fixed to each other at at least two ends.

13. An actuator or motor according to claim 11, wherein said base units are curved membranes or plate structures.

14. An actuator or motor according to claim 10, wherein said cavities are filled with rubber-like material.

15. An actuator or motor according to claim 1, wherein said monolithic module also comprises control electronics generating phase shifted voltages and various feed-back and communication electronics of a sensor, said sensor measuring at least one characteristic such as force and position.

16. An actuator or motor arrangement having an actuator or motor having electromechanical material which alters its shape under the influence of an electric field, and a body, whereby motion relative said body is created by non-resonant repetition of small steps, said actuator or motor comprising at least one monolithic module with electrodes integrated in said electromechanical material, said monolithic module being a sintered block and having at least one passive part and at least two active elements, one independent contact point at each active element being against said body, which contact points are positionable independently of each other in at least two independent directions relative to said passive part of said monolithic module, whereby said monolithic module by itself or in combination with others is used for creating said motion, and in that said body has a wedge shape.

17. An actuator or motor according to claim 16, wherein said body comprises an elastic material.

18. An actuator or motor according to claim 16, wherein said body is an elastic structure.

19. An actuator system having a number of modules comprising electromechanical material which alters its shape under the influence of an electric field, whereby motion relative a body is created by non-resonant repetition of small steps, said modules being monolithic modules with electrodes integrated in said electromechanical material, each of said monolithic modules being a sintered block and having at least one passive part and at least two active elements, one independent contact point at each active element being provided against said body, which contact points are positionable independently of each other in at least two independent directions relative to said passive part of said monolithic module, and a bellow-shaped tube arranged for creating a normal force between said monolithic modules.

20. Method of driving an actuator or motor having electromechanical material altering its shape under the influence of an electric field, comprising the step of moving said actuator or motor by repeating small steps, said step of moving further comprises the step of driving at least one monolithic module by itself or in combination with other monolithic modules, said monolithic module being a sintered block and having electrodes integrated in said electromechanical material, positioning at least two contact points on each of said monolithic modules independently of each other in at least two independent directions relative to a passive part of said monolithic modules, and the step of rotating at least one of said monolithic modules relative to another, having a wedge shape, or relative to a separate unit having a wedge shape, thereby transferring a rotating motion into a tilting motion.

21. Method of driving an actuator or motor according to claim 20, wherein said step of rotating comprises the steps of creation and moving of constrictions of a central tube, causing peristaltic motion of any liquids within said central tube.