Piezoelectric accelerometer

Patent metadata

Field	Value
Publication number	US-2017003162-A1
Application number	US-201615264231-A
Country	US
Kind code	A1
Filing date	Sep 13, 2016
Priority date	Aug 29, 2013
Publication date	Jan 5, 2017
Grant date	—

Abstract

At least some of the example embodiments are methods including measuring motion of a body by deflecting a first cantilever portion of a sensing element, and deflecting a second cantilever portion of a sensing element, the second cantilever element of the sensing element disposed opposite the first cantilever element. A first voltage having a first polarity is created across electrical leads responsive to the deflecting of the cantilever portions opposite the direction of the first acceleration of the body. The sensing element is supported by way of a mounting plate medially disposed on the sensing element.

First claim

What is claimed is:

1 . A method comprising:
measuring motion of a body by
deflecting a first cantilever portion of a sensing element, the deflecting along a direction opposite a direction of a first acceleration of a body;
deflecting a second cantilever portion of a sensing element, the deflecting along a direction opposite the direction of first acceleration of the body, the second cantilever element of the sensing element disposed opposite the first cantilever element;
creating a first voltage having a first polarity, the first voltage created across electrical leads responsive to the deflecting of the cantilever portions opposite the direction of the first acceleration of the body;
wherein the sensing element is supported by way of a mounting plate medially disposed on said sensing element, the mounting plate defining a periphery comprising:
a first arcuate curve portion;
a second arcuate curve portion disposed on opposite first arcuate curve portion;
a first chord connecting a first end of the first arcuate curve portion with a first end of the second arcuate curve portion; and
a second chord connecting a second end of the first arcuate curve portion with a second end of the second arcuate curve portion.

2 . The method of claim 1 wherein after creating the first voltage, the measuring motion of a body further comprises:
deflecting the first cantilever portion of the sensing element, the deflecting along a direction opposite a direction of a second e acceleration of the body;
deflecting the second cantilever portion of a sensing element, the deflecting opposite the direction of direction of the second e acceleration of the body;
creating a second voltage having a second polarity, the second voltage created across electrical leads responsive to the deflecting, and the second polarity opposite the first polarity; and
wherein the direction of the second acceleration of the body is opposite the direction of the first acceleration of the body.

3 . The method of claim 1 further comprising towing a streamer in a body of water, wherein the sensing element is disposed on the streamer.

4 . The method of claim 3 , wherein the motion of the body comprises motion of a fluid particle, the method further comprising producing a geophysical data product from the measured motion of the fluid particle indicative of certain properties of subsurface rock below the body of water.

5 . A streamer comprising:
a cable; a hydrophone coupled to the cable, the hydrophone sensitive to acoustic pressure fluctuations; and an accelerometer coupled to the cable, the accelerometer comprising:
a first piezoelectric element having a first polarization, the first piezoelectric element defines an upper surface;
a second piezoelectric element having a second polarization, the second piezoelectric element defines a lower surface parallel to the upper surface of the first piezoelectric element, and the first polarization aligned with the second polarization;
a first mounting plate that defines a first aperture;
the first and second piezoelectric elements extending through the first aperture such that the first mounting plate transects the first and second piezoelectric elements, the piezoelectric elements define a first cantilever portion on a first side of the first mounting plate, and the piezoelectric elements define a second cantilever portion on a second side of the first mounting plate opposite the first side;
wherein the first mounting plate defines a periphery comprising:
a first arcuate curve portion;
a second arcuate curve portion disposed on opposite first arcuate curve portion;
a first chord connecting a first end of the first arcuate curve portion with a first end of the second arcuate curve portion; and
a second chord connecting a second end of the first arcuate curve portion with a second end of the second arcuate curve portion;
wherein the first mounting plate comprises a metallic member disposed abutting the first piezoelectric element, the first piezoelectric element further comprising a metallized layer on the upper surface of the piezoelectric element; and
wherein the metallic member is soldered to the metallized layer.

6 . The streamer of claim 5 wherein the accelerometer is configured to produce an electrical signal in response to an acceleration component in a direction of sensitivity perpendicular to the upper surface, and the accelerometer configured to produce substantially no electrical signal in response to pressure acting on the accelerometer.

Assignees

• Pgs Geophysical As

Inventors

• Fernihough Robert Alexis Peregrin

Classifications

• G01P15/09

  by piezoelectric pick-up · CPC title

• G01V1/162

  Details · CPC title

• G01V1/38

  specially adapted for water-covered areas (G01V1/28 takes precedence) · CPC title

• G01H11/08 Primary

  using piezoelectric devices · CPC title

• G01P15/0922

  of the bending or flexing mode type · CPC title