Method of controlled pulse driving of a stacked PZT bender bar for dipole acoustic radiation

Patent metadata

Field	Value
Publication number	US-9541657-B2
Application number	US-201113821847-A
Country	US
Kind code	B2
Filing date	Sep 9, 2011
Priority date	Sep 10, 2010
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A bender bar is presented. The bender bar includes at least two pairs of piezoelectric elements arranged on an inert element to adjust the response frequency of the bender bar. In some embodiments, the piezoelectric elements can be stacked on the inert element. In some embodiments, the piezoelectric elements are symmetrically arranged with respect to the bender bar such that a gap is formed between piezoelectric elements arranged on the inert element.

First claim

What is claimed is:

1. A bender bar, comprising:
an inert element having a length, width and thickness, the inert element further having a first side and a second side;
a first pair of piezoelectric elements, wherein one of the first pair of piezeoelectric elements is bonded to the first side and one of the first pair of piezoelectric elements is bonded to the second side;
a second pair of piezoelectric elements, wherein each of the piezoelectric elements of the second pair are bonded to one of the piezoelectric elements of the first pair;
wherein one of the piezoelectric elements of the second pair is bonded to the first side of the inert element in relation to one of the first pair in such a way that a first gap is formed between the piezoelectric element of the first pair and the piezoelectric element of the second pair;
wherein one of the piezoelectric elements of the second pair is bonded to the second side of the inert element in relation to one of the first pair in such a way that a second gap is formed between the piezoelectric element of the first pair and the piezoelectric element of the second pair;
a third pair of piezoelectric elements, each of the third pair of piezoelectric elements being bonded to one of the first pair of piezoelectric elements;
a fourth pair of piezoelectric elements, each of the fourth pair of piezoelectric elements being bonded to one of the second pair of piezoelectric elements such that the first gap and the second gap are maintained;
a driver circuit coupled to each pair of piezoelectric elements to independently drive each of the pair;
wherein the first pair of piezoelectric elements are bars of width less than or equal to the width of the inert element and a length less than or equal to the length of the inert element; and
wherein the second pair of piezoelectric elements are bars of width less than or equal to the width of the piezoelectric elements of the first pair and length less than the length of the piezoelectric elements of the first pair.

2. The bender bar of claim 1 , wherein the first and second pairs of piezoelectric elements are arranged in a symmetrical fashion with respect to the inert element.

3. The bender bar of claim 1 , wherein the third pair and the fourth pair are each bars of piezoelectric material with width less than or equal to that of the first pair and the second pair and lengths less than the first pair and the second pair.

4. The bender bar of claim 1 , wherein the third pair and the fourth pair are each partial elliptical slabs such that one element of the third pair and one element of the fourth pair form an ellipse with a major axis and a minor axis, the minor axis being less than or equal to the width of the first pair and the major axis being less than the length of the combination of the length of one element of the first pair, a width of the first gap, and the length of one element of the second pair.

5. The bender bar of claim 1 , further including
sensors coupled to provide feedback signals to the driver circuit,
wherein the driver circuit adjusts at least the phase between driving voltages applied to each pair of the at least two pairs of piezoelectric elements in response to the feedback signals.

6. The bender bar of claim 1 , further comprising a driver circuit to independently drive each pair of the piezoelectric elements with controlled pulses by controlling a frequency, amplitude or shape of the pulses for each pair of the piezoelectric elements based on at least one of a thickness of the piezoelectric elements, a stiffness k, and mass m of the bender bar, to thereby generate symmetric bending modes with a harmonic displacement in a Z-direction of a center point of the bender bar.

7. The bender bar of claim 1 , wherein the first and second gaps are positioned substantially at a center line of the inert element.

8. A method of adjusting a frequency response of a bender bar, comprising:
arranging a first and second pair of piezoelectric elements on an inert element having a length, width, and thickness, the inert element further having a first side and a second side;
attaching one of the first pair of piezoelectric elements on the first side and attaching one of the first pair of piezoelectric elements on the second side;
attaching each of the second pair of piezoelectric elements to one of the first pair of piezoelectric elements; and
independently applying driving voltages to the first and second pairs of piezoelectric elements;
wherein one of the piezoelectric elements of the second pair is bonded to the first side of the inert element in relation to one of the first pair in such a way that a first gap is formed between the piezoelectric element of the first pair and the piezoelectric element of the second pair;
wherein one of the piezoelectric elements of the second air is bonded to the second side of the inert element in relation to one of the first air in such a way that a second is formed between the piezoelectric element of the first pair and the piezoelectric element of the second pair;
attaching a third pair of piezoelectric elements, each of the third pair of piezoelectric elements being bonded to one of the first pair of piezoelectric elements;
attaching a fourth pair of piezoelectric elements, each of the fourth pair of piezoelectric elements being bonded to one of the second pair of piezoelectric elements such that the first gap and the second gap are maintained; and
wherein the second pair of piezoelectric elements are bars of width less than or equal to a width of the piezoelectric elements of the first pair and length less than a length of the piezoelectric elements of the first pair.

9. The method claim 8 , wherein arranging the at least two pairs of piezoelectric elements includes arranging the elements in a symmetrical fashion with respect to the inert element.

10. The method of claim 8 , further including:
receiving a feedback signal; and
adjusting the driving voltages in response to the feedback signal.

11. The method of claim 8 , further comprising independently driving each pair of the piezoelectric elements with controlled pulses by controlling a frequency, amplitude or shape of the pulses for each pair of the piezoelectric elements based on at least one of a thickness of the piezoelectric elements, a stiffness k, and mass m of the bender bar, to thereby generate symmetric bending modes with a harmonic displacement in a Z-direction of a center point of the bender bar.

12. The method of claim 8 , wherein the first and second gaps are positioned substantially at a center line of the inert element.

Assignees

• Mandal Batakrishna
• Li Chen
• Halliburton Energy Services Inc

Inventors

• Mandal Batakrishna
• Li Chen

Classifications

• G01V1/159 Primary

  using piezoelectric or magnetostrictive driving means (generating mechanical vibrations by using piezoelectric or magnetostrictive effect in general, B06B1/06, B06B1/08) · CPC title

• H01L41/042

  Electricity · mapped topic

• H01L41/0933

  Electricity · mapped topic

• H01L41/04

  Electricity · mapped topic

• H10N30/802 Primary

  Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits · CPC title