Elastomer actuator and a method of making an actuator

• US 20070277356A1
• Filed: 08/06/2007
• Published: 12/06/2007
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: Danfoss A/S
• Original Assignee: Danfoss A/S
• Inventors: Gravesen, Peter, Benslimand, Mohamed
• Granted Patent: US 7,895,728 B2
• Time in Patent Office: Days
• US Class Current: 29/25.350
• CPC Class Codes: H02N 1/002 Electrostatic motors
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/057 by stacking bulk piezoelectric or electrostrictive bodies and electrodes
• CPC Class Codes: H10N 30/098 Forming organic materials
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• CPC Class Codes: H10N 30/506 of cylindrical shape with stacking in radial direction, e.g. coaxial or spiral type rolls
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/4908 Acoustic transducer
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.
• CPC Class Codes: Y10T 29/49171 with encapsulating
• CPC Class Codes: Y10T 29/49176 with molding of electrically insulating material
• CPC Class Codes: Y10T 29/49226 Electret making

Abstract

A tubular elastomer actuator with a shape in a cross-sectional view which shape exposes at most one single axis of symmetry of a specific length, e.g., an oval shape. The actuator could be made from a sheet made from a plurality of plate shaped elements which are laminated together and rolled. Each plate shaped element may have a corrugation that gives the element an anisotropic structure, and contains an electrode on only one surface. The actuator displacement is the result of shrinkage displacement of the plate shaped elements upon the application of electrical field across their thickness.

Claims

1. A method of making a rolled elastomer actuator, said method comprising the steps of:

forming a sheet from layers of elements, each comprising a body of an elastomer material and an electrode in contact with a surface of the body; and

rolling up the sheet to form a hollow tubular portion with a shape wherein any line of symmetry extending between two opposite points on a periphery in a cross-section perpendicular to the longitudinal direction has a length which is different from any other such line of symmetry.

2. The method according to claim 1, wherein the tubular portion is filled with a liquid elastomer material which is subsequently hardened to form an elastomer core for the tubular portion.

3. A method for fabricating an actuator comprising the steps of:

providing an elastomeric body having a corrugated surface;

coating the corrugated surface of the elastomeric body with an electrode forming an element; and

combining a plurality of elements to form a sheet defining an actuator.

4. The method according to claim 3 further comprising the step of:

rolling the sheet into a tubular actuator.

5. The method according to claim 4 wherein the tubular actuator has an asymmetrical cross-section.

6. The method according to claim 4 wherein the tubular actuator has a non-circular cross-section.

7. The method according to claim 4 wherein the tubular actuator has an elliptical cross-section.

8. The method according to claim 4, wherein the tubular actuator is filled with a liquid elastomer material which is subsequently hardened to form an elastomer core for the tubular actuator.

9. The method according to claim 3 wherein the core of the actuator is hollow.

10. The method according to claim 3 wherein the sheet comprises elements of a first type and elements of a second type.

11. The method according to claim 10 wherein:

the element of the first type comprises a conductive terminal of a first type; and

the element of the second type comprises a conductive terminal of a second type,

wherein the conductive terminal of the first type is offset from the conductive terminal of the second type when the elements are stacked.

12. The method according to claim 3 wherein the elastomeric body has at least one corrugated surface having a corrugated profile.

13. The method according to claim 12 wherein the corrugated surface is molded.

14. The method according to claim 13 wherein at least one electrode is deposited on the corrugated surface of the elastomeric body and forms electrode corrugations corresponding to the corrugations of the corrugated surface of the elastomeric body.

15. The method according to claim 4 wherein a longitudinal axis of the tubular actuator is substantially perpendicular to direction in which corrugations of the corrugated surface extend.

16. A method of fabricating an actuator comprising the steps of:

providing a body of elastomeric material having a first side and a second side;

molding at least one side of the body to define a corrugated surface;

coating the corrugated surface with an electrode; and

forming a tubular actuator from the body and the electrode.

17. The method according to claim 16 wherein the actuator has an asymmetrical cross-section.

18. The method according to claim 16 wherein the tubular actuator has a non-circular cross-section.

19. The method according to claim 16 wherein the tubular actuator has an elliptical cross-section.

20. The method according to claim 16, wherein the tubular actuator is filled with a liquid elastomer material which is subsequently hardened to form an elastomer core for the tubular actuator.

21. The method according to claim 16, wherein the tubular actuator is formed by multiple layers of elastomeric material and electrode.

22. The method according to claim 21 wherein the tubular actuator comprises elements of a first type and elements of a second type.

23. The method according to claim 22 wherein:

the element of the first type comprises a conductive terminal of a first type; and

the element of the second type comprises a conductive terminal of a second type,

wherein the conductive terminal of the first type is offset from the conductive terminal of the second type when the elements are stacked.

24. The method according to claim 16 wherein the electrode coating the corrugated surface of the elastomeric material forms electrode corrugations corresponding to the corrugations of the corrugated surface of the elastomeric material.

25. The method according to claim 16 wherein a longitudinal axis of the tubular actuator is substantially perpendicular to direction in which corrugations of the corrugated surface extend.