Elastomer actuator and a method of making an actuator

• US 7,400,080 B2
• Filed: 09/18/2003
• Issued: 07/15/2008
• Est. Priority Date: 09/20/2002
• Status: Expired due to Fees

• Current Assignee: Danfoss A/S
• Original Assignee: Danfoss A/S
• Inventors: Benslimand, Mohamed Yahia, Gravesen, Peter
• Primary Examiner(s): Dougherty; Thomas M
• Application Number:
  US10/528,503
• Publication Number:
  US 20060066183A1
• Time in Patent Office: 1,762 Days
• Field of Search: 310/311, 310/328, 310/366, 310/369
• US Class Current: 310/369
• 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. An actuator comprising:

a tubular portion extending in a longitudinal direction, the tubular portion comprising a body of an elastomeric material arranged between two electrodes,

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,

wherein the tubular portion is formed by rolling up a sheet comprising at least two elements each comprising a body of an elastomeric material and an electrode attached to a first surface thereof,

wherein deformation of the body is restricted in a first direction and supported in a another, second, direction, wherein the sheet comprises includes;

an element of a first type comprising a conductive terminal of a first type being in electrical contact with the electrode of the element

an element of a second type comprising a conductive terminal of a second type being in electrical contact with the electrode of the element, and

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

2. The actuator according to claim 1, wherein the second direction is parallel to the longitudinal direction.

3. The actuator according to claim 1, wherein the first direction is substantially perpendicular to the second direction.

4. The actuator according to claim 1, wherein the body and the electrode comprise corrugations extending in the first direction.

5. The actuator according to claim 1, wherein the:

element of the first type further comprises a conductive terminal of a second type being electrically isolated from the electrode of the element, and wherein

the element of the second type further comprises a conductive terminal of a first type being electrically isolated from the electrode of the element,

wherein the conductive terminals of the first type are in mutual electrical contact and the conductive terminals of the second type are in mutual electrical contact when the elements are stacked.

6. The actuator according to claim 1, wherein the conductive terminals of the first type cover a first peripheral rim portion of the body of an elastomeric material, and the conductive terminals of the second type cover a second peripheral rim portion of the body of an elastomeric material.

7. The actuator according to claim 1, wherein elements of the first type are arranged alternately elements of the second type.

8. An actuator comprising:

a tubular portion extending in a longitudinal direction, the tubular portion comprising a body of an elastomeric material arranged between two electrodes,

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,

wherein the tubular portion is formed by rolling up a sheet comprising at least two elements each comprising a body of an elastomeric material and an electrode attached to a first surface thereof,

wherein deformation of the body is restricted in a first direction and supported in a another, second, direction, and wherein the tubular portion is formed by rolling of the sheet around a core of an elastomeric material.

9. An actuator comprising:

a tubular portion extending in a longitudinal direction, the tubular portion comprising a body of an elastomeric material arranged between two electrodes,

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, wherein the tubular portion is filled with a core of an elastomeric material.

10. The actuator according to claim 9, wherein the core is softer than the elastomeric material forming the tubular portion.

11. The actuator according to claim 9, wherein the core is made by filling a cavity limited by the tubular portion and two closure parts with a liquid elastomer material which is subsequently hardened while the tubular portion is stretched axially.

12. An actuator comprising:

an elastomeric material arranged between two electrodes forming a tubular portion extending in a longitudinal direction and having a cross-section, wherein the cross-section of the tubular portion is asymmetrical;

wherein the tubular portion is formed by multiple layers of elastomeric material and electrode; and

wherein the tubular portion comprises elements of a first type and elements of a second type.

13. The actuator according to claim 12 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.

14. The actuator according to claim 12 wherein the elastomeric material has at least one corrugated surface.

15. The actuator according to claim 14 wherein the corrugated surface is molded.

16. The actuator according to claim 15 wherein at least one electrode is deposited on the corrugated surface of the elastomeric material and forms electrode corrugations corresponding to the corrugations of the corrugated surface of the elastomeric material.