Ultrasonic Actuator

• US 20190312530A1
• Filed: 06/29/2017
• Published: 10/10/2019
• Est. Priority Date: 07/01/2016
• Status: Active Grant

• Current Assignee: Physik Instrumente (PI) GmbH & Co. KG
• Original Assignee: Physik Instrumente (PI) GmbH & Co. KG
• Inventors: POLZER, Thomas
• Granted Patent: US 11,012,005 B2
• Time in Patent Office: Days
• CPC Class Codes: H02N 2/002 using only longitudinal or radial modes
• CPC Class Codes: H02N 2/0055 Supports for driving or driven bodies; Means for pressing driving body against driven body
• CPC Class Codes: H02N 2/006 Elastic elements, e.g. springs in general F16F1/00
• CPC Class Codes: H02N 2/0065 Friction interface friction linings F16D69/00
• CPC Class Codes: H02N 2/026 by pressing one or more vibrators against the driven body
• CPC Class Codes: H02N 2/04 Constructional details
• CPC Class Codes: H02N 2/06 Drive circuits; Control arrangements or methods
• CPC Class Codes: H02N 2/103 by pressing one or more vibrators against the rotor
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices

Abstract

A hollow-cylindrical ultrasonic actuator is disclosed a central axis, an inner peripheral surface facing the central axis and an outer peripheral surface facing away from the central axis and spaced apart from the inner peripheral surface, a closed inner contour curve, a closed outer contour curve, at least one electrode, and an electromechanical material provided between opposed electrodes. In a non-actuated state of the ultrasonic actuator, a curvature of the inner contour curve or of an outer contour curve includes at least three mutually spaced-apart local maximum points.

Claims

1. A hollow-cylindrical ultrasonic actuator comprising:

a central axis (ZA);

an inner peripheral surface facing the central axis (ZA) and an outer peripheral surface facing away from the central axis (ZA) and spaced apart from the inner peripheral surface, wherein in a cross-section perpendicular to the central axis (ZA) the inner peripheral surface defines a closed inner contour curve and the outer peripheral surface defines a closed outer contour curve;

at least one electrode arranged on each of the inner peripheral surface as well as the outer peripheral surface; and

an electromechanical material provided between opposed electrodes, vibration deformations to be excited in the ultrasonic actuator by electrically actuating the electrodes, these vibration deformations being utilizable for driving an element when in frictional contact with the ultrasonic actuator, wherein in a non-actuated state of the ultrasonic actuator, at least one of the inner contour curve or the outer contour curve includes at least three spaced-apart local points of maximum curvature.

2. The hollow-cylindrical ultrasonic actuator according to claim 1, wherein the points of maximum curvature are spaced apart equidistantly along the inner and/or outer contour curve.

3. The hollow-cylindrical ultrasonic actuator according to claim 1, wherein the number of points of maximum curvature corresponds to an odd natural number.

4. The hollow-cylindrical ultrasonic actuator according to claim 1, wherein a curvature of the inner contour curve or of the outer contour curve changes continuously along its respective profile.

5. The hollow-cylindrical ultrasonic actuator according to claim 1, wherein a shape of the inner contour curve is geometrically similar to a shape of the outer contour curve and wherein a thickness of the hollow-cylindrical ultrasonic actuator is equal along a periphery.

6. The hollow-cylindrical ultrasonic actuator of claim 1 in combination with:

a support device to form an arrangement, wherein the support device contacts the inner peripheral surface of the ultrasonic actuator at a section where a curvature of the inner contour curve exhibits a local maximum.

7. The combination according to claim 6, wherein contacts of the support device with the inner peripheral surface of the ultrasonic actuator comprise:

spherical sections or spherical elements.

8. The combination according to claim 7, wherein the spherical sections or the spherical elements are elastically deformable.

9. The combination according to claim 6, wherein the support device comprises:

elastically deformable sections configured as flexure hinges.

10. The combination according to claim 6, wherein the support device has a star-shaped geometry which comprises:

arm sections which extend from a common center.

11. The arrangement according to claim 10, wherein a distal end of each arm section comprises:

a spherical element, and wherein each arm section includes a deformable section formed integrally therewith and configured as a flexure hinge.

13. The hollow-cylindrical ultrasonic actuator according to claim 2, wherein the number of points of maximum curvature corresponds to an odd natural number.

14. The hollow-cylindrical ultrasonic actuator according to claim 13, wherein a curvature of the inner contour curve or of the outer contour curve changes continuously along its respective profile.

15. The hollow-cylindrical ultrasonic actuator according to claim 14, wherein a shape of the inner contour curve is geometrically similar to a shape of the outer contour curve and wherein a thickness of the hollow-cylindrical ultrasonic actuator is therefore equal along a periphery.

16. The hollow-cylindrical ultrasonic actuator of claim 15 in combination with:

a support device to form an arrangement, wherein the support device contacts the inner peripheral surface of the ultrasonic actuator at a section where a curvature of the inner contour curve exhibits a local maximum.

12. A method for driving an element, the method comprising:

providing a hollow-cylindrical ultrasonic actuator having electrodes, an electromechanical material provided between opposed electrodes, a central axis (ZA), and an inner peripheral surface facing the central axis (ZA) and an outer peripheral surface facing away from the central axis (ZA) and spaced apart from the inner peripheral surface, wherein in a cross-section perpendicular to the central axis (ZA) the inner peripheral surface defines a closed inner contour curve and the outer peripheral surface defines a closed outer contour curve, the method comprising;

arranging at least one electrode on each of the inner peripheral surface as well as the outer peripheral surface; and

electrically activating the electrodes to excite the vibration deformations, these vibration deformations driving an element in frictional contact with the ultrasonic actuator, wherein in a non-actuated state of the ultrasonic actuator, at least one of the inner contour curve or the outer contour curve include at least three spaced-apart local points of maximum curvature.