Ultrasonic motor having generators formed of cooperating and spaced apart first and second sub-generators

Patent metadata

Field	Value
Publication number	US-11114954-B2
Application number	US-201916288658-A
Country	US
Kind code	B2
Filing date	Feb 28, 2019
Priority date	Mar 5, 2018
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

An ultrasonic motor and method are disclosed with an element to be driven and a plate-shaped ultrasonic actuator made of polarized electromechanical material with at least two friction elements arranged on one of its side. The ultrasonic actuator can include at least two generators for acoustic standing waves and each of the generators can include two cooperating and spaced sub-generators, and one respective sub-generator of a generator is located between the sub-generators of an adjacent generator, and the sub-generators of one generator are arranged in mirror image to the sub-generators of an adjacent generator. A polarization direction of the electromechanical material of one of the two sub-generators of one generator differs from the polarization direction of the electromechanical material of the other sub-generator of the same generator.

First claim

The invention claimed is:

1. An ultrasonic motor, comprising:
an element to be driven;
an ultrasonic actuator made of polarized electromechanical material in the form of a plate having a length L, a height H and a thickness T, and with main surfaces, and side surfaces that are smaller in terms of area than said main surfaces and connect said main surfaces to each other;
at least two friction elements arranged on at least one of said side surfaces and provided for frictional contact with said element to be driven;
at least two generators (Gl, Gr) which are each formed of an excitation electrode, a general electrode, and electromechanical material disposed between said excitation electrode and said general electrode, such that said ultrasonic actuator can be excited by applying electrical excitation voltage to said electrodes of said at least two generators (Gl, Gr) to form an acoustic standing wave usable for driving said element to be driven; and
each of said at least two generators (Gl, Gr) having first and second cooperating and spaced sub-generators, the first sub-generator of a generator of said at least two generators being respectively located between the first and second sub-generators of an adjacent generator of said at least two generators; and the first and second sub-generators of one generator of said at least two generators being arranged in mirror image to the first and second sub-generators of an adjacent generator of said at least two generators;
wherein a polarization direction of electromechanical material of the first sub-generator of one generator of said at least two generators (Gl, Gr) differs from a polarization direction of electromechanical material of the second sub-generator of the same generator (Gl, Gr).

2. The ultrasonic motor according to claim 1 , wherein the polarization directions of said electromechanical material of the first and second sub-generators of said at least two generators (Gl, Gr) run opposite to each other.

3. The ultrasonic motor according to claim 1 , wherein each of said at least two generators (Gl, Gr) comprises:
a plurality of excitation electrodes and general electrodes, and a layer of electromechanical material is respectively arranged between adjacent electrodes.

4. The ultrasonic motor according to claim 3 , wherein the polarization directions within adjoining layers of electromechanical material run opposite to each other.

5. The ultrasonic motor according to claim 1 , wherein the length L of said ultrasonic actuator corresponds to 3.5 times to 3.9 times its height H.

6. A method for actuating an ultrasonic motor having an element to be driven; an ultrasonic actuator made of polarized electromechanical material in the form of a plate having a length L, a height H and a thickness T, and with main surfaces, and side surfaces that are smaller in terms of area than said main surfaces and connect said main surfaces to each other; at least two friction elements arranged on at least one of said side surfaces and provided for frictional contact with said element to be driven; at least two generators (Gl, Gr) which are each formed of an excitation electrode, a general electrode, and electromechanical material disposed between said excitation electrode and said general electrode, such that said ultrasonic actuator can be excited by applying electrical excitation voltage to said electrodes of said at least two generators (Gl, Gr) to form an acoustic standing wave usable for driving said element to be driven; and
each of said at least two generators (Gl, Gr) having first and second cooperating and spaced first and second sub-generators, the first sub-generator of a generator of said at least two generators being respectively located between the first and second sub-generators of an adjacent generator of said at least two generators; and the first and second sub-generators of one generator of said at least two generators being arranged in mirror image to the first and second sub-generators of an adjacent generator of said at least two generators;
wherein a polarization direction of electromechanical material of the first sub-generator of one generator of said at least two generators (Gl, Gr) differs from a polarization direction of electromechanical material of the second sub-generator of the same generator (Gl, Gr), the method comprising:
providing an electrical excitation device for applying an electrical voltage to said excitation electrodes and/or said general electrodes;
applying an electrical voltage to the first and second sub-generators of said at least two generators (Gl, Gr) by way of said electrical excitation device so that a diagonal transverse acoustic standing wave is formed in said ultrasonic actuator by which said friction elements each perform a motion along a trajectory that is inclined relative to said side surface on which said friction elements are arranged such that a defined phase shift is given between the motions of said friction elements.

7. The method according to claim 6 , wherein the phase shift between the motions of said friction elements is substantially 180°.

8. The method according to claim 6 , comprising:
providing a harmonic or a non-harmonic alternating voltage by said electrical excitation device.

9. The method according claim 6 , comprising:
applying two different alternating voltages to said first and second sub-generators of said at least two generators (Gl, Gr).

10. The method according to claim 9 , wherein said two alternating voltages have a different amplitude and/or a different frequency and/or a different phase.

11. The ultrasonic motor according to claim 2 , wherein each of said at least two generators (Gl, Gr) comprise:
a plurality of excitation electrodes and general electrodes, and a layer of electromechanical material is respectively arranged between adjacent electrodes.

12. The ultrasonic motor according to claim 11 , wherein the length L of said ultrasonic actuator corresponds to 3.5 times to 3.9 times its height H.

13. The method according to claim 7 , comprising:
providing a harmonic or a non-harmonic alternating voltage by said electrical excitation device.

14. The method according claim 13 , comprising:
applying two different alternating voltages to said first and second sub-generators of said at least two generators (Gl, Gr).

Assignees

• Phys Instrumente Pi Gmbh & Co Kg

Inventors

• Wischnewskiy Wladimir
• Wischnewski Alexej

Classifications

• H02N2/08 Primary

  using travelling waves {, i.e. Rayleigh surface waves} · CPC title

• H02N2/026 Primary

  by pressing one or more vibrators against the driven body · CPC title

• H02N2/0075

  Electrical details, e.g. drive or control circuits or methods · CPC title

• H02N2/002 Primary

  using only longitudinal or radial modes · CPC title

• H01L41/09

  Electricity · mapped topic