Enhanced displacement piezoelectric motor

• US 20080100179A1
• Filed: 10/20/2006
• Published: 05/01/2008
• Est. Priority Date: 10/20/2006
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Clingman, Dan J., Ruggeri, Robert T.
• Granted Patent: US 7,663,294 B2
• Time in Patent Office: Days
• US Class Current: 310/332
• CPC Class Codes: H10N 30/2041 Beam type
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00

Abstract

A mechanical energy generating apparatus is provided. The apparatus includes a shape changing flexure beam connected at opposing distal ends to first lever arms of a pair of opposing tilt connectors. The apparatus additionally includes a bias beam connected at opposing ends to second lever of the tilt connectors. The tilt connectors are pivotally connected to an adjustable length base such that a distance between the tilt connectors can be adjusted to flex the bias beam and exert a force on the second lever arms of the tilt connectors. The force exerted by the bias beam is transferred to the first lever arms and flexes the flexure beam to approximately a critical buckling stress point of the flexure beam. The flexure beam has a center portion configured to oscillate between a first displacement position beyond the critical buckling stress point, in a first direction, and a second displacement position beyond the buckling stress point, in the an opposing second direction, in response to an oscillating energy field applied across the flexure beam.

Claims

1. A mechanical energy generating apparatus comprising:

a shape changing flexure beam connected at a first distal end to a first lever arm of a first tilt connector and connected at an opposing second distal end to a first lever arm of a second tilt connector;

a bias beam connected at a first distal end to a second lever arm of the first tilt connector and connected at an opposing second distal end to a second lever arm of the second tilt connector; and

a base pivotally connected to the first and second tilt connectors such that a distance between the first and second tilt connectors is such that the bias beam is flexed to exert a force on the second lever arms of the first and second tilt connectors that is transferred to the first lever arms of the first and second tilt connectors to flex the flexure beam to approximately a critical buckling stress point of the flexure beam;

the flexure beam having a center portion configured to oscillate between a first displacement position beyond the critical buckling stress point in a first direction and a second displacement position beyond the buckling stress point in the an opposing second direction in response to an oscillating energy field applied across the flexure beam.

2. The apparatus of claim 1, wherein the flexure beam comprises a bimorph piezoelectric flexure beam and the oscillating energy field comprises an alternating polarity voltage applied across the flexure beam.

3. The apparatus of claim 1, wherein the flexure beam comprises at least one layer of an electrostrictive materials and the oscillating energy field comprises an alternating polarity voltage applied across the flexure beam.

4. The apparatus of claim 1, wherein the flexure beam comprises at least one layer of a magnetostrictive material and the oscillating energy field comprises an alternating polarity magnetic field applied across the flexure beam.

5. The apparatus of claim 1, wherein the flexure beam comprises a first flexure beam and the bias beam comprises a second flexure beam configured to operate as the bias beam for the first flexure beam and as a second flexure beam operating 180°

out of phase with the first flexure beam such that the first flexure beam also operates as a bias beam for the second flexure beam.

6. The apparatus of claim 1, wherein the flexure beam comprises a first flexure tab extending from the first distal end and a second flexure tab extending from the second distal end, the first and second flexure tabs structured to pivotally connect the flexure beam to the respective first and second tilt connectors.

7. The apparatus of claim 1, wherein the flexure beam comprises a first roller pin affixed to the first distal end and a second roller pin affixed to the second distal end, the first and second roller pins structured to pivotally connect the flexure beam to the respective first and second tilt connectors.

8. The apparatus of claim 1, wherein the apparatus further comprises a first pivot axle adjustably extending from a first distal end of the base to pivotally connect the first tilt connector to the base and a second pivot axle adjustably extending from a second distal end of the base to pivotally connect the second tilt connector to the base, an extension distance of the first and second pivot axles adjustable to adjust the distance between the first and second tilt connectors.

9. A mechanical energy generating apparatus comprising:

a first tilt connector including a first lever arm, a second lever arm and a fulcrum arm;

a second tilt connector including a first lever arm, a second lever arm and a fulcrum arm;

a shape changing flexure beam connected at a first distal end to the first lever arm of the first tilt connector and connected at an opposing second distal end to the first lever arm of the second tilt connector;

a bias beam connected at a first distal end to the second lever arm of the first tilt connector and connected at an opposing second distal end to the second lever arm of the second tilt connector; and

a base pivotally connected at a first distal end to the first tilt connector fulcrum arm and pivotally connected at an opposing second distal end to the second tilt connector fulcrum arm such that a distance is maintained between the first and second tilt connectors that causes the bias beam to flex and exert a force on the second lever arms of the first and second tilt connectors that is transferred to the first lever arms of the first and second tilt connectors that causes the flexure beam to flex to approximately a critical buckling stress point so that approximately all energy used to apply a voltage across the flexure beam is utilized to produce displacement of a center of the flexure beam beyond the critical buckling stress point;

the polarity of the voltage across the flexure beam cyclically alternateable to oscillate the center of the flexure beam between a first displacement position beyond the critical buckling stress point in a first direction and a second displacement position beyond the buckling stress point in an opposing second direction, the oscillation of the center of the flexure beam adapted to generate mechanical energy deliverable to a mechanical device connectable to the flexure beam.

10. The apparatus of claim 9, wherein the flexure beam comprises one of:

a bimorph piezoelectric flexure beam having two layers of piezoelectric material and the oscillating energy field comprises an alternating polarity voltage applied across the flexure beam;

an electrostrictive flexure beam having at least one layer of an electrostrictive material and the oscillating energy field comprises an alternating polarity voltage applied across the flexure beam; and

a magnetostrictive flexure beam having at least one layer of a magnetostrictive material and the oscillating energy field comprises an alternating polarity magnetic field applied across the flexure beam.

11. The apparatus of claim 9, wherein the flexure beam comprises a first flexure beam and the bias beam comprises a second flexure beam configured to operate as the bias beam for the first flexure beam and as a second flexure beam operating 180°

out of phase with the first flexure beam such that the first flexure beam also operates as a bias beam for the second flexure beam.

12. The apparatus of claim 9, wherein the flexure beam comprises a first flexure tab extending from the first distal end and a second flexure tab extending from the second distal end, the first and second flexure tabs structured to pivotally connect the flexure beam to the respective first and second tilt connectors.

13. The apparatus of claim 9, wherein the flexure beam comprises a first roller pin affixed to the first distal end and a second roller pin affixed to the second distal end, the first and second roller pins structured to pivotally connect the flexure beam to the respective first and second tilt connectors.

14. The apparatus of claim 9, wherein the apparatus further comprises a first pivot axle adjustably extending from a first distal end of the base to pivotally connect the first tilt connector to the base and a second pivot axle adjustably extending from a second distal end of the base to pivotally connect the second tilt connector to the base, an extension distance of the first and second pivot axles adjustable to adjust the distance between the first and second tilt connectors in order to flex the flexure beam to approximately the critical buckling stress point.

15. A method for generating mechanical energy using a piezoelectric motor, said method comprising:

pivotally connecting a first distal end of a piezoelectric flexure beam to a first lever arm of a first tilt connector and pivotally connecting at an opposing second distal end to a first lever arm of the second tilt connector;

pivotally connecting a first distal end of a bias beam to a second lever arm of the first tilt connector and pivotally connecting at an opposing second distal end to a second lever arm of the second tilt connector;

pivotally connecting a base to the first and second tilt connectors;

adjusting a distance between the first and second tilt connectors to cause the bias beam to flex and exert a force on the second lever arms of the first and second tilt connectors that is transferred to the first lever arms of the first and second tilt connectors that causes the flexure beam to flex to approximately a critical buckling stress point of the flexure beam so that approximately all energy used to apply a voltage across the flexure beam is utilized to produce displacement of a center of the flexure beam beyond the critical buckling stress point;

oscillating the voltage across the flexure beam to oscillate a center of the flexure beam between a first displacement position beyond the critical buckling stress point in a first direction and a second displacement position beyond the buckling stress point in the an opposing second direction, the oscillation of the center of the flexure beam generating mechanical energy deliverable to a mechanical device connectable to the flexure beam.

16. The method of claim 15 further comprising oscillating the voltage across the flexure beam at a frequency below a resonant frequency of the flexure beam.

17. The method of claim 15, wherein the flexure beam comprises a first flexure beam and the bias beam comprises a second flexure beam and the method further comprises:

utilizing the second flexure beam as the bias beam for the first flexure beam; and

utilizing the first flexure as a second bias beam to operate the second flexure beam 180°

out of phase with the first flexure beam.

18. The method of claim 15, wherein:

pivotally connecting the first distal end of the piezoelectric flexure beam to the first lever arm of the first tilt connector comprises connecting a first flexure tab extending from the first distal end of the flexure beam to the first lever arm of the first tilt connector; and

pivotally connecting the opposing second distal end to a first lever arm of the second tilt connector the flexure beam comprises connecting a second flexure tab extending from the second distal end of the flexure beam to the first lever arm of the second tilt connector.

19. The method of claim 15, wherein:

pivotally connecting the first distal end of a piezoelectric flexure beam to the first lever arm of the first tilt connector comprises pivotally connecting a first roller pin affixed to the first distal end of the flexure beam to the first lever arm of the first tilt connector; and

pivotally connecting the opposing second distal end to the first lever arm of the second tilt connector comprises pivotally connecting a second roller pin affixed to the second distal end of the flexure beam to the first lever arm of the second tilt connector.

20. The method of claim 15, wherein a first adjustable pivot axle extends from a first distal end of the base to pivotally connect the first tilt connector to the base and a second adjustable pivot axle extends from a second distal end of the base to pivotally connect the second tilt connector to the base, and wherein adjusting the distance between the first and second tilt connectors comprises adjusting an extension distance of the first and second pivot axles to adjust the distance between the first and second tilt connectors in order to flex the flexure beam to approximately the critical buckling stress point.

21. A mechanical energy generating apparatus comprising a shape changing flexure beam cooperatively coupled with a bias device adapted to apply an axial compressive force to opposing distal ends of the flexure beam that is greater than a critical buckling force of the flexure beam to soften the flexure beam such that electrical signals applied to the flexure beam produce enhanced displacement of a center of the flexure beam beyond a critical buckling stress point of the flexure beam and the apparatus can be operated at frequencies below the resonant frequency of the flexure beam.