Piezoelectric damping mechanism

• US 4,104,920 A
• Filed: 04/01/1977
• Issued: 08/08/1978
• Est. Priority Date: 04/01/1977
• Status: Expired due to Term

• Current Assignee: Kearfott Guidance and Navigation Corporation
• Original Assignee: Singer Company (SVP Holdings Ltd.)
• Inventors: Albert, William C., Hohenstein, Robert M.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/783,916
• Time in Patent Office: 494 Days
• Field of Search: 73/517 AV, 73/517 R, 73/DIG. 1, 73/DIG. 4, 310/319, 310/328
• US Class Current: 73/514.14
• CPC Class Codes: G01P 1/003 used for damping
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: Y10S 73/01 Vibration
• CPC Class Codes: Y10S 73/04 Piezoelectric

Abstract

A damping mechanism suitable for use with a vibrating beam accelerometer comprising a piezoelectric block mounted between the vibrating beam force transducer and the pendulum of the instrument. The proof mass, or pendulum, is mounted for pendulous motion about a pair of hinge means. Vibration of the instrument causes opposite charges to appear on electrodes which are on two opposite faces of the block. These charged electrodes are connected to each other by a resistor and so a current will flow through the resistance to neutralize the charge. The resistor will then dissipate the vibration energy as heat. This energy dissipation is effectively damping.

Claims

1. A vibration damping device comprising:

an evacuated housing containing said damping device,

a support,

a vibrating beam cantileveredly mounted on said support said beam being activated due to acceleration forces acting thereon,

a piezoelectric block mounted at one end to the free end of said vibrating beam and at the other end to said support for generating a source of current resulting from strain forces acting upon it due to the vibration of said vibrating beam, and

means in electrical series with said piezoelectric block for dissipating the energy released by said piezoelectric beam whereby the acceleration forces acting on said vibrating beam is effectively damped.

2. The damping device of claim 1 comprising:

first and second electrodes mounted on opposite sides of said piezoelectric block and in electrical contact therewith, said electrodes being in capacitive relationship with each other and establishing a charge thereon resulting from the generation of electric forces in said piezoelectric block.

3. The damping device of claim 2 comprising:

a resistor in electrical series with said electrodes whereby energy generated by said piezoelectric beam is dissipated through said resistor.

4. The damping device of claim 3 comprising:

inductive means connected in series with said resistor and tuned for resonance with said vibrating beam whereby the energy released by said piezoelectric block is dissipated.

5. The damping device of claim 4 comprising:

inductive means in parallel with said resistor and said electrodes and tuned for resonance with said vibrating beam whereby all of the energy released by said piezoelectric block is dissipated across said resistor due to the parallel circuit of said electrodes and inductive means effecting an infinite impedance.

6. The damping device of claim 5 comprising:

a proof mass cantileveredly mounted about a hinge to said support said proof mass being connected to said piezoelectric block and moving in a plane orthogonal to the vibrating plane of said vibrating beam as a result of acceleration forces acting on said vibrating beam and said resistor being mounted exteriorly of said housing to dissipate the energy released from said piezoelectric block exteriorly of said housing.

7. The damping device of claim 6 comprising:

a piezoelectric block loaded in tension compression relative to said vibrating beam.

8. The damping device of claim 6 comprising:

a piezoelectric block loaded in a bending mode relative to said vibrating beam.

9. A vibration damping device for a vibrating beam accelerometer comprising:

an evacuated housing containing said damping device,

a support,

an elongated vibrating beam cantileveredly mounted on said support said beam being forced into vibration by acceleration forces acting transversely to the long dimension of said beam,

a proof mass cantileveredly mounted on said support and moveable in a plane orthogonal to the plane of said forces acting on said vibrating beam,

a piezoelectric block mounted to the free ends of said proof mass and said vibrating beam said piezoelectric block being loaded in tension compression relative to said vibrating beam and generating an electric current resulting from strain forces acting upon it due to the motion of said vibrating beam,

first and second electrodes mounted on opposite sides of said piezoelectric block and in electrical circuit with said piezoelectric block, and

a resistor mounted exteriorly of said housing and in electrical series with said electrodes whereby the electric current generated by said piezoelectric block is dissipated through said resistor dampening the vibrations of said vibrating beam.

10. The damping device of claim 9 comprising:

inductive means connected in electrical series with said resistor and tuned for resonance with said vibrating beam.

11. The damping device of claim 9 comprising:

inductive means in a parallel electrical circuit with said resistor and said electrodes said parallel circuit being tuned for resonance with said vibrating beam whereby the electrical energy generated by said piezoelectric block is dissipated across said resistor due to the parallel circuit of said electrodes and inductive means effecting an infinite impedance to said electrical energy.

12. A vibration damping device comprising:

an evacuated housing containing said damping device,

a support,

a vibrating beam cantileveredly mounted on said support said beam being activated due to acceleration forces acting thereon,

a proof mass cantileveredly mounted to said support and moveable in a plane orthogonal to said vibrating beam,

a piezoelectric block mounted to the free ends of said proof mass and said vibrating beam for generating a source of current resulting from strain forces acting upon at due to the vibration of said vibrating beam, and

means in electrical series with said piezoelectric block for dissipating energy released by said piezoelectric beam whereby the acceleration forces acting on said vibrating beam is effectively damped.